United States
Environmental Protection
\r ^1 # %Agency
Office of Water
EPA 823-D-21-002
October 2021
Technical Support for Fish Tissue Monitoring for
Implementation of EPA's 2016 Selenium Criterion
Draft
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Technical Support for Fish Tissue Monitoring for
Implementation of EPA's 2016 Selenium Criterion
Draft
While this document cites statutes and regulations that contain requirements applicable to Clean
Water Act (CWA) implementation programs it does not impose legally binding requirements on
EPA, states, authorized tribes, other regulatory authorities, or the regulated community, and
may not apply to a particular situation based upon the circumstances. EPA, state, tribal and
other decision makers retain the discretion to adopt approaches on a case-by-case basis that
differ from those provided in this technical support document as appropriate and consistent with
statutory and regulatory requirements. EPA may update this document as new information
becomes available. In addition to this document, EPA has related documents that provide
considerations and recommendations on implementing the national CWA section 304(a)
recommended selenium criterion for freshwater, which are a\>ailable at EPA's selenium website:
https://www.epa.sov/wqc/aquatic-Ufe-criterion-selemxm.
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Table of Contents
1.0 Introduction 1
1.1 EPA's National CWA section 304(a) Recommended Chronic Aquatic Life Selenium Criterion
in Freshwater 1
1.2 Selenium Technical Support Materials 3
1.3 Document Overview 3
2.0 Monitoring Strategy 4
2.1 Tissue Type 5
2.1.1 Egg-ovary Tissue Sample 8
2.1.2 Whole-body and Muscle Tissue Samples 9
2.2 Sample Type 11
2.2.1 Composite Samples 11
2.2.2 Individual Samples 15
2.3 Target Species 16
2.4 Sampling Locations 22
2.4.1 Water Body Type 23
2.4.2 Water Body Size 24
2.4.3 Site-specific Studies for Water Column Translations 24
2.4.4 Point Sources 25
3.0 Leveraging Existing Fish Tissue Monitoring Programs and Sample Designs 26
3.1 Augmenting Existing Fish Tissue Monitoring Programs 26
3.1.1 Consistency with Existing Programs 26
3.1.2 Temporal Considerations 28
3.1.3 Spatial Considerations 29
3.2 Existing Resources and Information 30
3.2.1 Available Expertise 30
3.2.2 Existing Guidance 32
3.2.3 Using Existing Data to Enhance Selenium Monitoring 35
4.0 Sample Analysis 35
4.1 Analytical Chemistry 35
4.2 Data Analysis 38
Literature Cited 40
Appendix A: Egg and Ovary Sample Preparation 48
References 51
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Appendix B: Spawning Seasons for Example Fish Assemblages from Select U. S.
Watersheds 52
References 52
Appendix C: Conversion of Wet to Dry Tissue Weight 61
References 62
Appendix D: Extended List of Potential Target Species for Monitoring of Selenium in
Fish Tissue 64
References: 91
Appendix E: Calculation of Composite Trophic Transfer Factors 92
Tables
Table 1: Summary of the Recommended Freshwater Selenium Ambient Chronic Water Quality Criterion
for Protection of Aquatic Life 2
Table 2. Sampling Considerations Associated with Different Types of Fish Tissue 7
Table 3. Recommended Fish Target Species for Collection Based on Selenium Sensitivity and
Bioaccumulation Potential 20
Table 4: Recommended Documents for Additional Guidance 34
Table 5: List of Test Procedures for Total Selenium in Solids and Biota 37
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List of Acronyms
cw
Cold water
CWA
Clean Water Act
ECio
10% effect concentration
liM
Micron
MDL
Method detection limit
MPCA
Minnesota Pollution Control Agency
NAMC-SWG
North American Metals Council-Selenium Work Group
NCCA
National Coastal Condition Assessment
NO A A
National Oceanic and Atmospheric Administration
NPDES
National Pollutant Discharge Elimination System
QA/QC
Quality assurance/quality control
QL
Quantitation limit
SETAC
Society of Environmental Toxicology and Chemistry
SSD
Species sensitivity distribution
TMDL
Total maximum daily load
TSM
Technical support materials
TTF
Trophic transfer factor
USEPA
United States Environmental Protection Agency
USFWS
United States Fish and Wildlife Service
USGS
United States Geological Survey
WQC
Water quality criterion
WQS
Water quality standards
WW
Warm water
WW
Wet weight
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Definitions
Anadromous fish
Fish with a life cycle that is divided between fresh and saltwater, including fish migrating to
spawn in freshwater. Migrations should be cyclical, predictable, and cover more than 100 km
(FishBase 2016).
Asynchronous spawners
Eggs are released in batches over a period of time that can last days or even months (Murua and
Saborido-Rey 2003).
Fecundity
The physiological maximum potential reproductive output of an individual (usually female) over
its lifetime (Bradshaw and McMahon 2008).
Gravid
Having the body distended with ripe eggs (FishBase 2016).
Indeterminate fecundity
Potential annual fecundity is not fixed before the onset of spawning and eggs can develop at any
time during the spawning season (FishBase 2016).
Iteroparous
Producing offspring in successive batches, for example annual or seasonal batches, as is the case
in most fishes (FishBase 2016).
Oocyte
Female sex cell which develops into an ovum. Oogonia become oocytes when meiosis begins,
and specialized cells surround each oocyte to form a follicle. The oocyte undergoes maturation in
preparation for spawning as an egg (modified from FishBase 2016).
Potamodromous
Fish species that spend their whole life in freshwater, but generally migrate for spawning
purposes, typically back to a natal upstream tributary from a mainstream river or between
connected lake and river systems. Migrations should be cyclical and predictable and cover more
than 100 km (FishBase 2016).
Semelparous
Producing all offspring at one time, such as in most salmon. Usually these fish die after
reproduction (FishBase 2016).
Site
In the context of site-specific criteria, a "site" may be a state, region, watershed, water body, or
segment of a water body. A "site" for fish sampling is a specific water body segment.
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Synchronous spawners
Eggs are released in a single episode during each breeding season (Murua and Saborido-Rey
2003).
Vitellogenesis
The process by which the yolk is formed and accumulated in the ovum. This is also the period
when nutrients stored in the liver are transferred to the developing oocytes in the ovary or ovaries
(FishBase 2016)
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1.0 Introduction
1.1 EPA's National CWA section 304(a) Recommended Chronic
Aquatic Life Selenium Criterion in Freshwater
In 2016, the United States Environmental Protection Agency (EPA) updated its national Clean
Water Act (CWA) section 304(a) recommended chronic aquatic life criterion for selenium in
freshwater systems to reflect the latest scientific information. This information indicates that
toxicity to aquatic life is driven by dietary exposures and that the reproductive life-stages of egg-
laying vertebrates are the most sensitive to the toxic effects of selenium. The criterion has four
criterion elements: (1) a fish egg-ovary criterion element; (2) a fish whole-body and/or muscle
criterion element; (3) a water column criterion element (one value for lentic and one value for
lotic aquatic systems); and (4) a water column intermittent criterion element (to account for
potential chronic effects from short-term exposures to high concentrations in lentic and lotic
aquatic systems) (see Table 1). Under EPA's 2016 CWA 304(a) recommended selenium
criterion, the fish tissue criterion elements have primacy over water column elements, except
where there are no fish, where fish tissue data do not meet state or tribal quality assurance
procedures, or for water bodies with new discharges where selenium concentrations in fish tissue
might not have stabilized (USEPA 2021a). EPA also recommends that the egg-ovary tissue
criterion element has primacy over whole-body and muscle tissue criterion elements.
Toxicity data indicate that the selenium concentration in fish eggs and ovaries is the most robust
and consistent measurement endpoint directly tied to adverse reproductive effects in aquatic
organisms. Toxicity to developing embryos and larvae is directly linked to egg selenium
concentration (USEPA 2021a). EPA derived the whole-body, muscle tissue, and water column
elements from the egg-ovary element so that states and authorized tribes could more readily
implement water quality criteria (WQC) based on EPA's national CWA section 304(a)
recommended selenium criterion. The assessment of the available data on chronic selenium
exposure for fish, invertebrates, and amphibians indicated that a criterion element derived from
fish is expected to be protective of the aquatic community, since other taxa appear to be less
sensitive to selenium than fish. EPA did not develop an acute criterion for selenium when it
updated the chronic criterion because, although selenium may cause acute toxicity at high
concentrations, the most deleterious effects on aquatic organisms are due to selenium's
bioaccumulative properties. The chronic effects of bioaccumulated selenium occur at lower
concentrations than acute effects.
In the case of bioaccumulative compounds like selenium, acute toxicity studies do not address
risks that result from chronic exposure to chemicals via the diet (i.e., through the food web
pathway). Such studies also do not account for the accumulation kinetics of many
bioaccumulative compounds, such as selenium, and may underestimate effects from long-term
accumulation in some types of aquatic systems. As described in EPA's 2021 Revision to:
Aquatic Life Ambient Water Quality Criterion for Selenium-Freshwater 2016 (hereafter referred
to as Aquatic Life Ambient Water Quality Criterion for Selenium-Freshwater 2016), EPA also
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included an intermittent exposure criterion element to provide protection from the most
significant effects of selenium toxicity, reproductive toxicity, by protecting against selenium
bioaccumulation in the aquatic ecosystem resulting from short-term, high concentration exposure
events (USEPA 2021a). EPA recommends, as stated in the Aquatic Life Ambient Water Quality
Criterion for Selenium-Freshwater 2016, that states and authorized tribes1 adopt into their water
quality standards (WQS) a selenium criterion that includes all four criterion elements. For more
information see EPA's Aquatic Life Ambient Water Quality Criterion for Selenium-Freshwater
2016, which can be found at https://www.epa.gov/svstem/files/documents/2021-08/selenium-
freshwater2016-2021 -revision.pdf.
Table 1: Summary of the Recommended Freshwater Selenium Ambient Chronic Water Quality
Criterion for Protection of Aquatic Life.
Media Type
Fish Tissue1
Water Column4
Criterion
Element
Egg-ovary 2
Fish Whole-body
or Muscle3
Monthly
Average
Exposure
Intermittent Exposure5
Magnitude
15.1 mg/kg dry
weight
8.5 mg/kg dry
weight whole-
body
or
11.3 mg/kg dry
weight muscle
(skinless, boneless
fillet)
1.5 (ig/L in lentic
aquatic systems
3.1 (ig/L in lotic
aquatic systems
WQCint =
WQCsQ—rfay bk0.033 (corresponding to 1 day).
6. Fish tissue data provide instantaneous point measurements that reflect integrative accumulation of selenium over
time and space in fish population(s) at a given site.
1 Throughout this document and in the CWA. the term "states" means the fifty states, the District of Columbia, the
Commonwealth of Puerto Rico, the United States Virgin Islands, Guam, American Samoa, and the Commonwealth
of the Northern Mariana Islands. The term "authorized tribe" means those federally recognized Indian tribes with
authority to administer a CWA WQS program.
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1.2 Selenium Technical Support Materials
EPA has prepared a four-volume set of documents to provide recommendations to states,
authorized tribes, and other agencies for implementing WQC based on the national CWA section
304(a) recommended selenium criterion (USEPA 2021a). These four documents constitute the
Technical Support Materials for EPA's Aquatic Life Ambient Water Quality Criterion for
Selenium-Freshwater 2016 (USEPA 2021a). Each document of the set focuses on a specific
aspect of implementation of the national CWA section 304(a) recommended selenium criterion.
Together, these four EPA documents provide information that will assist states and authorized
tribes with adopting WQC based on EPA CWA section 304(a) recommended selenium criterion
and implementing it in various CWA programs.
1) Technical Support for Adopting and Implementing EPA's Selenium 2016 Criterion in
Water Quality Standards, Draft, provides recommendations for the adoption and
implementation of the national CWA section 304(a) recommended selenium criterion,
including the various flexibilities available to states and tribes using WQS tools.
2) Technical Support for Fish Tissue Monitoring for Implementation of EPA's 2016 Selenium
Criterion, Draft: provides an overview on how to establish or enhance existing fish tissue
monitoring programs to facilitate implementation of the fish tissue-based criterion
elements in the national CWA section 304(a) recommended selenium criterion.
3) Frequently Asked Questions: Implementing Water Quality Standards Based on EPA's
2016 Recommended Selenium Criterion in Clean Water Act Section 402 NPDES Permits,
Draft: is intended to help NPDES permit writers understand what permitting guidance
(i.e., state or tribal implementation procedures) may be appropriate to implement state and
authorized tribal WQS based on EPA's CWA section 304(a) recommended selenium
criterion. This set of FAQs also provides recommendations on how to establish water
quality-based effluent limits (WQBELs) in NPDES permits.
4) Frequently Asked Questions (FAQs): Implementing the 2016 Selenium Criterion in Clean
Water Act Sections 303(d) and 305(b) Assessment, Listing, and Total Maximum Daily
Load (TMDL) Programs, Draft, provides information on how to complete assessments,
list impaired waters, and develop TMDLs based on EPA approved WQS that adhere to
EPA's national CWA section 304(a) recommended selenium criterion, including all four
elements.
1.3 Document Overview
This document, Technical Support for Fish Tissue Monitoring for Implementation of EPA's 2016
Selenium Criterion, Draft, examines technical considerations for developing a robust sampling
program to characterize selenium concentrations in fish tissue for a variety of CWA
implementation programs (e.g. CWA section 303(d) listing and TMDLs). Some aspects of this
document can also be used to support the development of site-specific water column criterion
elements. Site-specific water column criterion elements can be developed by performing a site-
specific water column translation from the fish tissue elements of the criterion. See Appendix K
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of Aquatic Life Ambient Water Quality Criterion for Selenium-Freshwater 2016 (USEPA 2021a)
for site-specific approaches for translating between fish tissue and water column selenium
concentrations.
This document is intended to assist states and authorized tribes in planning enhancements to their
monitoring programs, not to limit the fish tissue data that can be used for waterbody assessments
with the recommended criterion. The recommended criterion applies to all species present in a
waterbody. EPA's regulations require that states and authorized tribes evaluate all existing and
readily available water quality-related data for assessment decisions (40 C.F.R. 130.7(b)(5)),
which for this criterion would include selenium data and information for any fish species. For
additional information about assessment decisions for this criterion, please refer to the
Frequently Asked Questions (FAQs): Implementing the 2016 Selenium Criterion in Clean Water
Act Sections 303(d) and 305(b) Assessment, Listing, and Total Maximum Daily Load (TMDL)
Programs, Draft (USEPA 2021b).
This document does not specifically address the site-specific modification of the fish tissue
criterion elements, which should be developed using fish assemblage data and the recalculation
procedure (USEPA 2013). States and authorized tribes that wish to develop site-specific fish
tissue criterion elements should engage their EPA regional office early in the process to ensure
the development and use of sound scientific analyses.
2.0 Monitoring Strategy
When considering enhancements to monitoring strategies for CWA implementation, EPA
recommends that agencies first review their existing fish tissue monitoring programs and
determine how best to incorporate collection of fish tissue samples for the implementation of the
aquatic life selenium criterion into the monitoring program. For example, existing fish tissue
monitoring programs will likely be collecting data to assess the risk of fish consumption to
human health. These monitoring programs may be designed with different objectives than
monitoring activities designed to assess attainment of an aquatic life criterion. These differences
need to be considered and reconciled when using an existing fish tissue monitoring program for
assessing the fish tissue criterion elements of the selenium aquatic life criterion.
The following sections review study design and sampling considerations regarding fish tissue
types, sample types, target species, and spatial and temporal variability. These topics should be
considered when collecting data to assess fish tissue concentrations against the fish tissue
criterion elements of the state's or authorized tribe's selenium aquatic life criterion or collecting
data to translate a fish tissue criterion element into a site-specific water column criterion element.
The relationship between fish sampling locations and timing, species' habits and natural history,
and the selenium source(s) should be understood and accounted for during the design of
sampling plans for criterion implementation. The fish tissue sampling methods should be
designed to characterize the variability of selenium in the target population, including areas of
high selenium bioaccumulation. The criterion establishes population level protection that is
measured by the population mean concentration. Therefore, sampling should be designed to
determine the mean selenium concentration in the fish tissue of the population. EPA encourages
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early discussions with EPA regions to assure that studies capture the appropriate data. Detailed
field collection procedures and sampling design considerations can be found in Guidance for
Assessing Chemical Contaminant Data for Use in Fish Advisories, Vol 1: Fish Sampling and
Analysis (EPA's Fish Advisory Guidance Volume 1) (USEPA 2000), the Field Sampling Plan
for the National Study of Chemical Residues in Lake Fish Tissue (USEPA 2002a), and EPA's
National Aquatic Resource Survey Field Operations Manuals for rivers and streams and Great
Lakes and coastal waters (USEPA 2019a, 2019b, 2015). Appendix A of this document presents
egg and ovary collection and sample preparation methods.
2.1 Tissue Type
EPA recommends sampling egg-ovary tissue for both assessment and site-specific water column
criterion element development purposes, when possible. From the toxicological standpoint, the
most representative measure of exposure to a toxic substance is its concentration at the site of
toxic action. In fish (the aquatic species most sensitive to selenium), the most ecologically
relevant sites of toxic action are the mature reproductive tissues of adults (ovaries) or early life
stages (vitellogenic eggs/larvae). This was a major point of consensus of the 2009 Society of
Environmental Toxicology and Chemistry (SETAC) Pellston workshop on selenium risk
assessment (Chapman et al. 2009). Therefore, the national CWA section 304(a) recommended
selenium criterion is based on reproductive effects in fish, as represented by selenium
concentrations in egg-ovary tissue.
While egg-ovary tissue of adult female fish is the most direct reflection of reproductive toxicity
in fish, samples of muscle or whole-body tissue from adult fish serve as robust alternatives and
may be collected for implementation purposes.
Collection of fish samples for egg-ovary analysis poses special challenges as only gravid female
fish can be sampled. Due to this constraint, the decision of what tissue type to collect should be
made based on the following considerations:
• Temporal. Most fish species that are synchronous spawners, spawn in the spring; whereas
fish tissue collection for fish consumption advisories typically occur in the late summer
or early fall, when contaminant loads in the edible portion of the fish are highest. Spring
sampling may also be challenging in states or tribal lands where rivers and streams have
high flows due to storm run-off and spring snow melt. Timing the collection of mature
eggs from asynchronous spawners can also be challenging, as these species can have eggs
in various stages of development at once.
• Spatial. Some fish species migrate to upstream areas to spawn and these areas may be
harder to access than higher order downstream segments that are inhabited during non-
spawning seasons.
• Size: It is difficult to collect and analyze egg-ovary tissue samples from small fish species
(e.g., certain species in the family Cyprinidae or Cyprinodontidae) due to the logistics of
the collection and the small amount of tissue available for analysis (number of eggs or
biomass).
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Due to these concerns, states and authorized tribes have considerable discretion when selecting
the fish tissue type to collect in their sampling protocols. The flexibility provided by being able
to collect data from multiple fish tissue types allows for leveraging existing monitoring capacity.
A number of the species that are good target species for selenium sampling could also be
commonly collected as muscle (fillet) samples in state and tribal fish tissue monitoring programs
for other contaminants (e.g., trout, salmon, bass, sunfish) (see section 2.3 for more information
on target species). The whole-body tissue criterion element also simplifies the collection and
processing of small fish species that may be the dominant trophic level in lower order stream
networks.
When developing a new or modifying an existing fish tissue monitoring strategy, states or
authorized tribes may want to consider funding and staff resources, opportunities to work with
other fish tissue monitoring programs, existing information on the spawning habits and size of
target species, and potential population level effects associated with using lethal sampling
techniques when deciding what fish tissue type to sample. To keep the public, stakeholders, and
EPA well informed, it is good practice for monitoring programs to describe in their sampling
protocols why they are sampling a particular tissue type. Similar considerations might also be
evaluated when selecting a tissue to sample for the development of a site-specific water column
criterion element. If possible, EPA recommends that egg-ovary tissue be sampled to conduct a
site-specific water column translation. Sampling considerations associated with different types of
fish tissue are presented in Table 2.
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Table 2. Sampling Considerations Associated with Different Types of Fish Tissue
Issue
Egg-ovary
Whole-body
Muscle/Fillet
Comments
Criterion
Hierarchy
Considerations
Has primacy in
the criterion;
supersedes other
fish tissue
criterion
elements and the
water column
criterion
elements
Supersedes
water column
criterion
elements; equal
consideration
to muscle tissue
Supersedes
water column
criterion
elements; equal
consideration to
whole-body
tissue
While selenium concentrations in
all three tissue types are
significantly correlated to
reproductive toxicity effects seen
in fish, egg-ovary concentrations
have the strongest relationship.
Ease of
collection
Difficult
Easy
Easy - except on
small fish
Egg-ovary samples are only
collected from gravid females;
there are seasonal and logistical
considerations, and species-
specific sampling windows. See
Appendices A and B.
Consistency
with existing
state & tribal
methods
Not typically
collected
Sometimes
collected
Primary tissue
collected
Whole-body samples might be
collected in special cases, such as
for certain human populations that
consume whole fish or for
ecological risk assessments.
Sample
availability
Limited - only
from gravid
females
Always
Always
For water bodies with small sized
species at top trophic levels,
whole-body may be the only
option due to issues collecting a
sufficient mass of muscle tissue.
Ability to make
composite
sample
Yes
Yes
Yes
Compositing can be used to
reduce the overall cost of an
analytical program, primarily by
reducing the number of samples
that must be analyzed to represent
an average concentration.
Compositing can also ensure that
enough mass is available for
chemical analyses. However, by
compositing samples, information
on the range of selenium
concentrations in individual
organisms is lost.
Ability to test
individual
sample
Yes, on larger
species; may be
difficult on small
species
Yes, on larger
species; may be
difficult on
small species
Yes, on larger
species; may be
difficult on
small species
Individual samples are valuable
when sampling from waters
known or suspected to be
impacted by selenium discharges
(see section 3.2.2), however the
need to analyze multiple
individual samples versus a few
composite samples can make them
more resource intensive to prepare
and expensive to analyze.
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2.1.1 Egg-ovary Tissue Sample
Selenium concentrations in all three tissue types are significantly correlated to reproductive
toxicity effects seen in fish; however, egg-ovary concentrations have the strongest relationship.
EPA recommends sampling fish egg-ovary tissue for assessment of the selenium aquatic life
criterion or for development of a site-specific water column criterion element, when possible.
Egg-ovary tissue refers to mature eggs, pre-spawn ovary tissue that contains mature eggs, or
both. As an oocyte grows into a mature egg, it passes through several stages of development (i.e.,
oogenesis, primary oocyte growth, cortical alveolus stage, vitellogenesis, maturation, and
ovulation) (Tyler and Sumpter 1996). During this egg development process, the oocyte size
increases dramatically as the yolk is developed. For example, the diameter of an undeveloped
oocyte of the rainbow trout is around 20 |im and the fully developed egg is about 4 mm
(Nagahama 1983). Selenium is transferred from an adult female fish to her eggs during
vitellogenesis. Eggs should not be collected until after this transfer has occurred. Appendix A of
this document presents egg and ovary collection and sample preparation methods.
Adult female fish must be collected during the late vitellogenic or pre-ovulatory periods of
oogenesis for the tissue concentrations to be scientifically and toxicologically meaningful. The
egg-ovary sample should represent the potential selenium load available to eggs and larvae
through maternal transfer. Egg-ovary tissue from pre-spawn, reproductively mature (also called
"gravid" or "vitellogenic") females is the preferable tissue to collect because it will give the most
accurate representation of potential selenium hazard to reproduction. Egg-ovary tissue data
provide point measurements that reflect integrative dietary accumulation, transfer, and deposition
of selenium over time and space in female fish at a given site. Research has shown that selenium
concentrations in egg-ovary tissue is strongly correlated with selenium in the maternal diet; the
selenium is transferred from the adult female to her eggs during vitellogenesis (Janz et al. 2010).
When using egg-ovary tissue for the implementation of the selenium criterion, states and
authorized tribes should carefully consider the difficulty in timing egg-ovary sampling with
spawning periods. Timing errors related to fish reproduction may result in data that falsely
indicate the selenium criterion is being met. Ovary tissue sampled from a female that is not
gravid will not be representative of the selenium concentrations of this tissue for a gravid
individual and is not appropriate for comparison to the egg-ovary criterion. A female is typically
gravid for a very small window of time for most synchronous species, and may occur in the
spring or early summer, or in the fall to early winter (see Appendix B). The timing of the
spawning season will depend on the species, geography, and a number of environmental cues
(e.g., temperature, flow, photoperiod). In northern latitudes or higher elevations, spawning may
occur slightly later than in southern latitudes or lower elevations. EPA recommends that states
and authorized tribes consult with local fish biologists, who may be in other state or tribal
agencies (e.g., Departments of Natural Resources, Departments of Fish and Game), when
designing sampling plans.
Reproductively mature females of most fish species, except indeterminate spawning species and
viviparous species (i.e., live bearing), will produce eggs that can be sampled for selenium. Ovary
tissue of synchronous spawners (e.g., species in the genus Oncorhynchus) typically contain
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oocytes that are all in the same stage of development. Fish species that spawn multiple times per
season (asynchronous, e.g., some species in the family Cyprinidae) have variable cycles of
oogenesis and commonly have ovary tissue that contains oocytes and eggs at all stages of
development (Nagahama 1983). In these asynchronous spawners, egg maturation may occur well
before, immediately prior to, or during the spawning season. For example, Lepomis cycmellus
(green sunfish) can spawn multiple times per season (Osmundson and Skorupa 2011, Chapman
et al. 2010). Thus, special care should be taken when sampling asynchronous species for egg-
ovary tissue, as the pre-spawn window can be hard to predict.
Given these concerns, EPA has the following recommendations when sampling female
asynchronous spawners: 1) if the fish is too small to easily sample the egg-ovary tissue, the
whole body should be sampled (including the eggs) and the selenium concentration should be
compared to the whole-body criterion element; 2) if fish are sampled during the reproductive
season and they are large enough to easily sample the egg-ovary tissue, this tissue should be
sampled (the 75% rule does not apply to egg-ovary composite samples, see section 2.2.1); and 3)
muscle tissue should not be sampled during the reproductive season as selenium may be depleted
from this tissue during this time.
The egg-ovary tissue criterion element has primacy over all other criterion elements of the
selenium water quality criterion. Most states and authorized tribes do not currently collect egg-
ovary tissue as part of their regular monitoring programs. EPA recognizes that many states and
authorized tribes may not have the resources to augment their existing monitoring programs to
include egg-ovary tissue collection. While egg-ovary remains the preferable tissue type, whole-
body or muscle tissue samples can be used as an alternative.
2.1.2 Whole-body and Muscle Tissue Samples
Whole-body and muscle tissue samples may be collected as an alternative to egg-ovary tissue.
Selenium concentrations in these tissues will provide representative information on selenium
bioaccumulation and ecological exposure at almost any time of the year (except pre- and post-
spawn windows for females). However, there will likely be some variation across seasons due to
dietary composition, temperature, depuration of selenium from tissue during vitellogenesis prior
to spawning, and other factors. If the sex of the fish can be determined, it is preferable to use
male fish for muscle or whole-body samples since the selenium levels in their tissues are stable,
regardless of reproductive state. The only time of year that should be avoided for collecting
whole-body or muscle tissue samples from female fish is directly pre- and post-spawn because
they could have reduced selenium concentrations in their tissues due to the recent transfer of
selenium to eggs (USEPA 2021a). The exception is small-bodied fish, particularly asynchronous
spawners, where the collection of egg-ovary tissue is impractical. In this instance, the whole
body should be collected (with the eggs if the fish is female) and compared to the whole-body
criterion element.
Summer and fall may be prime periods for whole-body and muscle tissue collection due to the
engorgement of populations to replenish fat and energy reserves post-spawn and for over-
wintering. Winter tissue collection is discouraged, except in subtropical regions where metabolic
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changes due to lower water temperatures do not occur. Whole-body and muscle tissue data
provide point measurements that reflect integrative dietary accumulation and deposition of
selenium in fish tissues over time and space in fish population(s) at a given site.
EPA is aware that some states and authorized tribes use muscle plugs in their monitoring
programs as an alternative to collecting muscle fillets. States or authorized tribes that utilize
plugs should be aware of certain considerations. Contaminant concentrations can vary
considerably depending on where the plug is taken from a fish. Plugs should be collected from a
descaled meaty portion of the dorsal muscle tissue, between the dorsal fin and lateral line
(USEPA 2019a). Waddell and May (1995) found that selenium concentrations in plugs from this
location were significantly correlated to adjacent muscle tissue. Studies with mercury have also
shown that this location results in a sample that has homogeneous concentrations and
concentrations that were similar to mean concentrations for a muscle fillet (Cizdziel et al. 2002).
Plugs provide very small tissue masses (about a gram of tissue per fish) and may not provide
enough biomass for reanalysis or quality assurance/quality control (QA/QC) analysis. This may
lead to difficulty confirming the quality of the sample analysis. In addition, relatively small
individuals may not recover from a muscle plug biopsy punch. Care should be taken to ensure
that there is enough tissue for the analytical method. In addition, states and authorized tribes may
want to establish species-specific conversion factors or regressions at the start of their sampling
program that quantify the relationship between the muscle plug concentration and the muscle
fillet concentration so that selenium concentrations from plugs can be appropriately compared to
the muscle tissue criterion element. Currently, EPA is conducting a study to better define the
relationship between selenium concentrations in muscle plugs and muscle fillets. Soon EPA will
have more information about the representativeness of muscle plugs and the analytical
techniques for processing muscle plugs.
States or authorized tribes might choose to use whole-body or muscle tissue samples because
egg-ovary tissue is not available year-round, or because existing monitoring programs can
incorporate such selenium analysis into their existing fish tissue monitoring strategies. It is
reasonable to collect whole-body or muscle tissue samples to gather data when adding selenium
fish tissue sampling into an existing monitoring program or sampling for selenium in areas
without known sources. If data indicates the need for a site-specific criterion or criterion element,
agencies may want to expand their sampling to include egg-ovary tissue. States or authorized
tribes might also choose to use whole-body samples because small-bodied species are the most
appropriate to sample in a particular situation (Beatty and Russo 2014). In some low order
streams only small-bodied species may be available for sampling. Collecting whole-body
samples in these situations will allow for enough tissue mass for selenium analyses.
A specific case where sampling whole-body or muscle tissue is recommended over sampling
egg-ovary is for sampling juvenile Pacific (smolt) salmonids. Anadromous fish species like
salmon start their lives in freshwater, then as juveniles (e.g., smolts) migrate to the ocean, where
they stay until adulthood before migrating back into freshwater to spawn. Notable among these
species are the Coho, Chum, and Chinook salmon, and marine adapted Rainbow Trout
(steelhead). Adult anadromous females (in the genus Oncorhynchus - except steelhead and
Brown Trout) stop eating prior to re-entering freshwater environments as part of the
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physiological modifications required for the migratory spawning process, and thus, lack
exposure to freshwater selenium sources. They are also semelparous (except steelhead), meaning
they die after spawning so there is no post-spawn residual exposure. Since adults of these species
are not residents of the water body, the selenium concentrations will not be representative of
localized freshwater selenium sources (see section 6.4.1 of EPA's Aquatic Life Ambient Water
Quality Criterion for Selenium-Freshwater 2016) (USEPA 2021a). Given this lifecycle, it is not
appropriate to sample adult semelparous anadromous fish for assessment of freshwater water
bodies, as their selenium concentrations will not be representative of selenium exposure from
where they are sampled. Instead, the juvenile fish from these species should be sampled, so they
will reflect local selenium concentrations. An exception are landlocked variants of Striped Bass
that cannot migrate out to sea, or hybrids (e.g., "wipers" which are striped bass-white bass
crosses) in the Midwest. Adult fish in these landlocked populations may be representative of
localized freshwater selenium concentrations, and thus appropriate for sampling. Although more
uncertain, some studies indicate that selenium might affect endpoints such as juvenile growth
and survival (Hamilton et al. 1990, DeForest and Adams 2011), therefore the most appropriate
tissue to sample for Pacific anadromous salmon smolt is the whole body.
2.2 Sample Type
States and authorized tribes have flexibility in the type of sample that is collected to represent an
instantaneous measurement of selenium in a fish population at a given site (see criterion duration
footnote 6). Samples can include composites of multiple fish or the collection of individual fish
in the population. The field sampling and analytical considerations for both sample types are
described below.
2.2.1 Composite Samples
Composite samples are homogeneous mixtures of one type of tissue (e.g., egg-ovary, whole-
body, or muscle tissue) from two or more individual organisms of the same species collected at a
particular place and time and analyzed as a single sample. Composite samples can be useful for
collecting enough tissue from small fish species to perform the appropriate analyses. Composite
samples also allow for the analysis of additional target analytes if fish tissue samples are being
collected as part of a broader fish tissue monitoring effort. Because chemical analytical costs are
usually higher than field costs, using composite samples may be a cost-effective way to represent
average selenium tissue concentrations in target species sample populations, by reducing the
number of individual chemical analytical samples that are needed to characterize concentrations
in the sample population (Patil et al. 2011). Composite sampling may also help with the issue of
determining how to incorporate a sample with a concentration below the method detection limit
(MDL) into an average, as the composite represents a physical averaging of the samples (USEPA
2011). Composite samples have also been shown to provide equivalent estimates of the mean
compared to individual samples (Zhou et al. 2018, USEPA 1995). However, with composite
samples, extreme contaminant concentration values for individual organisms are attenuated (Patil
et al. 2011). Information from each individual sample is lost, which may mean losing
information about spatial or temporal trends. Also, if a set number of fish are being analyzed,
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compositing those fish rather than analyzing them individually will result in fewer data points,
which can potentially lead to having less power in statistical analyses. However, this will be
dependent on the data set and knowledge about the underlying sampling distribution. Hitt and
Smith 2015 found that composites of two to four fish did not decrease power relative to
individual samples when the sampling distribution was known (but power did decrease when an
empirical sampling distribution was constructed instead of being known), because the
composites had greater precision for estimating the mean.
Current EPA guidance on fish tissue monitoring recommends collecting three to ten individuals
for a composite sample for each target species, as availability allows (USEPA 2000). EPA's Fish
Advisory Guidance Volume 1 (USEPA 2000) also recommends collecting at least two composite
samples at each site, and encourages a third, in order to properly estimate the site variance. An
alternative approach may be to collect a greater number (five or greater) of smaller composites
(two to three fish), which would increase sample size and statistical power, but still minimize
resource expense compared to individual sampling (USEPA 2018, Hitt and Smith 2015). Section
6.1.2.7.1 of EPA's Fish Advisory Guidance Volume 1 ("Guidelines for Determining Sample
Sizes") maintains that it is not possible to recommend a single set of sample size
requirements for all fish contaminant monitoring studies (USEPA 2000). Rather, EPA presents a
more general approach to sample size determination that is both scientifically defensible and
cost-effective. Table 6-1 in that guidance shows the varying precision achieved by using
additional numbers of individuals per composite and additional replicate composite samples. The
data suggest that greater precision in the estimated standard error is gained by increasing the
number of replicate composite samples than by increasing the number of fish per composite
(USEPA 2000).
In EPA's National Lake Fish Tissue Study, composites were generally required to include five
fish (USEPA 2002a). This composite size represented a reasonable number of fish that also
satisfied statistical requirements for this study. If a state does not have previous data available for
its sampling location, EPA recommends, in most waters, composites of five fish be used for fish
tissue monitoring for CWA implementation of the selenium criterion. EPA recognizes that
sometimes it might not be possible to collect a five-fish composite. In these cases, EPA
encourages the state or authorized tribe to get as close to five fish as possible in the composite.
When the monitoring objectives include a desired level of statistical power, states and authorized
tribes should consider additional information to determine the appropriate number of individuals
per composite sample and number of replicate composite samples. Site-specific estimations of
the population variance of selenium concentrations, fisheries management considerations, and
statistical power considerations could be used to inform the sample size number to reach the
desired outcome for the monitoring objectives. For example, fewer replicate composite samples
and/or fewer individuals per composite sample may be required if the variance of the selenium
concentration in the fish population at a site is small. In this case, it would not be cost-effective
to use sample sizes that are larger than required to achieve the desired statistical power (Patil et
al. 2011). Alternatively, in some instances a state or tribe may want to collect composites
containing more than five fish or collect more replicates to have a more precise estimate of the
mean. This may be desired at sites that are expected to have high variability.
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The spatial variability of a site should also be considered when collecting composite samples. If
a site is particularly large with high variability in selenium throughout, the site may need to be
divided into subsites and composites collected from within each subsite to appropriately quantify
the selenium impacts at that site.
EPA recommends that fish used in a composite sample meet the following specifications
(USEPA 2000):
• All the same species.
• Of similar size so that the smallest individual in a composite is no less than 75% of the
total length (size) of the largest individual (the "75% rule"; this "75% rule" does not
apply to fish from which egg-ovary samples are collected).
• Collected at the same time (i.e., collected as close to the same time as possible but all
samples should be collected within a week of each other).
• Collected in sufficient numbers to provide a composite homogenate tissue sample of at
least 20 grams wet weight for selenium analysis.
EPA's Fish Advisory Guidance Volume 1 (USEPA 2000) recommends including an equal
number of fish in each composite sample and collecting two to three composite samples.
However, when sampling fish in waters potentially impacted by selenium, the number of
composite replicates may be determined on a case-by-case basis. This decision would primarily
be based on the amount of variation in selenium concentration expected at the site and the
number of individuals of the target species present at the site. States and authorized tribes who
want to ensure the highest level of statistical power may want to collect multiple smaller
composites to increase their sample size, which will increase their ability to detect differences
from the criterion (Hitt and Smith 2015, USEPA 2018).
As species have different selenium bioaccumulation potentials and different sensitivities to
selenium (USEPA 2021a), it is not scientifically defensible to create a composite sample that
consists of more than one species. Compositing individuals that are the same genus, but not the
same species is not appropriate. Accurate taxonomic identification is essential to prevent the
mixing of species in a sample.
EPA recognizes that, in contrast to other bioaccumulative contaminants in fish, selenium
concentrations are generally conserved across fish size (May et al. 2008). However, data on this
topic is limited and variation in selenium concentrations might still be introduced by sampling
fish of varying sizes. In particular, variation may be introduced if the species changes trophic
levels or feeding ranges over the course of its development. Therefore, EPA recommends
following the "75% rule" for the sizes of individual specimens included within a composite when
sampling whole-body or muscle tissue (this 75% rule recommendation does not apply to fish
collected for egg-ovary samples).
Individual organisms used in a composite sample ideally should be collected at the same time (if
possible) so that temporal changes in contaminant concentrations are minimized. A best practice
is to collect all organisms included in the composite sample within a week of each other so that
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the composite sample accurately reflects the selenium concentration of fish in that water body at
that time.
EPA recommends collecting a tissue sample of at least 20 grams wet weight (ww) for analysis,
for both composite samples and individual samples. When creating composite samples from
muscle tissue or egg-ovary tissue, an equal mass of homogenized tissue from each fish should be
combined to create the composite, and then 20 grams ww should be sampled from the composite
for analysis. When creating composite samples from whole bodies, all fish included in a
composite should meet the 75% rule. While the specific amount of tissue needed for analysis will
be dependent on the laboratory and analytical method used for analysis, 20 grams ww is a
reasonable estimate of the amount of tissue needed for typical selenium analyses. This mass
allows for 5 grams of tissue for the selenium analysis, 5 grams of tissue for a matrix spike
sample, 5 grams of tissue for dry weight analysis, and then a final 5 grams of tissue available in
case there is a problem with one of the other analyses and a procedure needs to be repeated. In
addition, a sample of this size allows for a quality control sample to be processed, which can
assure homogeneity of the tissue sample. If after these analyses enough remaining tissue mass is
available, agencies may want to retain tissue from the individual fish, in case future analyses are
wanted on the individuals. Most fish tissue samples for selenium analysis are processed as wet
tissue, resulting in a selenium concentration based on wet weight. As the national CWA section
304(a) recommended selenium criterion is based on a dry weight selenium concentration, an
analysis of the moisture content of the tissue needs to be performed and the wet weight
concentration needs to be converted to a dry weight concentration. See Appendix C for more
information on how to perform a wet weight to dry weight conversion. Monitoring agencies
typically collect composite samples for other analytes when sampling for fish consumption
advisories. If agencies currently discard or archive the composite homogenates that are in excess
of their current analytical needs, the excess tissue could be used, if adequate in mass, for
selenium analysis. Agencies could also collect additional tissue mass and add selenium as an
analyte to their sampling protocol.
EPA recognizes that if a state or authorized tribe collects muscle plugs they will likely be
collecting sample masses of less than 20g ww per fish. States and authorized tribes should assure
that the mass of tissue they are collecting and the analytical methods that they are using will
allow for accurate quantification of selenium. Compositing muscle plugs (one per fish from
multiple fish) may be one way to achieve sufficient mass for analysis.
EPA also recommends collecting an equal number of fish in each composite, as this simplifies
the statistical methods needed to analyze the results from this analysis. With equal numbers of
fish, the arithmetic average of the replicate composite measurements is an unbiased estimator of
the population mean. When unequal numbers are used, the arithmetic average is no longer
unbiased. Instead, a weighted average of the composite measurements is calculated, where the
weight for each composite reflects the number of fish in each composite sample. Oftentimes fish
are lost or damaged prior to compositing. When several fish are damaged or lost, the allocation
of the remaining fish to composites may be reconfigured to allow equal numbers of fish in
composites. During this reconfiguration process, a sampler may be faced with the choice of
either making composites composed of an equal number of fish or to follow the 75% rule. EPA
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recommends adhering with the 75% rule over having an equal number of fish in each composite
if both parameters cannot be met. If an equal number of fish cannot be included in each
composite, care should be taken to adjust the statistical procedures to account for the unequal
allocations (USEPA 2000).
2.2.2 Individual Samples
An individual sample is a discrete sample from a single fish, and can be an egg-ovary, whole-
body, or muscle (fillet) tissue sample. Use of composite samples for selenium fish tissue
monitoring is acceptable, but there are some instances where collecting individual fish may be
desirable.
Analysis of individual fish samples may be of interest when collecting data for a site-specific
study or for statistically evaluating patterns in selenium concentrations over time or space.
Analysis of individual fish may also be important when evaluating Se concentrations in critical
species, where understanding potential toxicity at the individual level is important. Analysis of
individual samples also allows for the evaluation of spatial and temporal differences among
individuals of a species of similar size or across the population of a species residing in a specific
water body.
For water bodies or segments that are known to be impacted by selenium, individual samples
describe the range of variability within a population including characterizing extreme values.
Individual samples may also provide better information about selenium source-exposure
relationships in large water bodies. Individual samples may also allow for the identification of
fish that are migrant or transient in a population, since that fish may have a higher or lower
concentration of selenium than other fish in the area. If studies are being conducted to monitor
trends, EPA recommends sampling fish of the same species at each location and at each time
interval so that data are spatially and temporally comparable.
If using individual samples to calculate mean selenium fish tissue concentrations, all fish should
be the same species and collected from the same water body (or site for large water bodies)
within the same sampling period (ideally within the same week). The fish should be of similar
size (within the 75% rule) and the samples should be of the same tissue type. EPA recommends
targeting at least five fish (per site or per location for larger sites) for individual analysis to
achieve measurements of a reasonable statistical power (see discussion of statistical power in the
"Composite Sample" discussion above). Greater or fewer fish samples may be needed based on
the variation of selenium at a particular site. Those entities desiring greater statistical power for
their analyses should collect additional fish samples. In the event that collecting at least five
individuals of one species is not possible, fewer specimens may be collected, but the statistical
power of the analysis will be affected (Hitt and Smith 2015). A power analysis should be
conducted in these situations to assure that enough data is being collected to detect a difference.
As with composite samples, EPA recommends collecting 20 grams ww as a minimum tissue
mass per individual fish for analysis and QA/QC.
With individual fish samples, as well as with fish samples collected to be a part of a composite
sample, EPA recommends documenting and reporting additional information about the fish
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samples to assist with interpretation of the data. Useful information to document includes the
species, length, age (if can be estimated), weight, and sex of the fish samples. Documenting
information about the sampling site and day can also be useful for data interpretation. Samplers
should note the location of collection by GPS if possible, sampling date and weather. Samplers
may want to also note flow rate and other characteristics about the site that may affect the
concentration of selenium at the sampling sites.
2.3 Target Species
The two main factors to consider when selecting a target fish species to sample for the
implementation of the national CWA section 304(a) recommended selenium criterion are (1) a
species' toxicological sensitivity to selenium, and (2) a species' bioaccumulation potential for
selenium. In addition, it is important to consider a species' potential for exposure to selenium.
EPA recommends that states and authorized tribes create a priority list of target species for
sampling teams. This list should identify the primary target species and alternatives species if the
primary species is not present or not present in sufficient numbers for sampling. If data cannot be
acquired for a desired target species, data from any fish species can be used to make assessment
decisions, as the criterion was developed for use with any fish species.
A species' toxicological sensitivity to selenium, for the purposes of implementing the national
CWA section 304(a) recommended selenium criterion, is defined as a species' or a surrogate
species' ECio (10% effect concentration). An ECio is the concentration of a chemical that is
estimated to result in a 10 percent effect in a measured chronic endpoint (e.g., growth,
reproduction, or survival). For the national CWA section 304(a) recommended selenium
criterion, a species' ECio is the concentration of selenium within egg-ovary tissue that results in a
10% effect on a reproductive endpoint for that species. Based on the best available and
acceptable reproductive-effect studies, as well as extensive analyses, EPA developed a species
sensitivity distribution (SSD) to support the derivation of the national CWA section 304(a)
recommended selenium criterion based on species' ECios (See Table 3.2 in USEPA 2021a). This
SSD for the national CWA section 304(a) selenium criterion indicates that the four most
sensitive genera for fish reproductive effects (in decreasing order) are Acipetiser, Lepomis,
Scilmo, and Oncorhynchns.
The bioaccumulation potential of a species is largely determined by its dietary composition and
the exposure of its prey items to selenium. Consumption of benthic invertebrates tends to drive
greater selenium bioaccumulation than consumption of plankton (Schneider et al. 2015,
Simmons and Wallschlager 2005). Amongst benthic organisms, the consumption of mollusks
tends to drive greater selenium bioaccumulation than consumption of other benthic invertebrates
(Luoma and Presser 2009, Stewart et al. 2004). Mollusks, such as mussels and clams, accumulate
selenium to a much greater extent than planktonic crustaceans and insects due to higher ingestion
rates of both suspended particulate-bound selenium (algae) and dissolved selenium from the
water column through filter feeding. Mollusks also have a lower selenium elimination rate (Johns
et al. 1988, Reinfelder et al. 1997). The greater bioaccumulation of selenium in benthic
organisms suggests that bottom feeding fish may have higher selenium levels, at least for the
lifecycle that ties their energy needs to food webs with benthic organisms. Other studies (Saiki et
al. 1993, Saiki and Lowe 1987) have shown that detritivores may also be exposed to high levels
of dietary selenium, as high concentrations of selenium were measured in detritus. The
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bioaccumulation potentials of organisms at higher trophic levels (such as piscivores) are
dependent on its food chain's cumulative exposure to and bioaccumulation of selenium. Trophic
transfer factors (TTFs) provide a numeric representation of bioaccumulation between a consumer
and its diet. A composite TTF (TTFcompos'to), which is the product of TTFs at each trophic level of
a consumer's food chain, represents the overall TTF for a higher trophic level organism. In
addition, composite TTFs account for the proportion of different food sources in a consumer's
diet. Evaluations of TTFs may be helpful in determining which species to target for sampling.
More information about TTFs can be found in Appendix B, Section 3.0 of the Aquatic Life
Ambient Water Quality Criterion for Selenium - Freshwater 2016 (USEPA 2021a). In addition,
an explanation of how composite TTFs are calculated is included in Appendix E.
As both a species' sensitivity to selenium and bioaccumulation of selenium influences whether it
will be impacted by selenium, states and authorized tribes should consider both when selecting a
target species and designing fish tissue sampling plans. EPA recommends the following
prioritization scheme for selecting a target species.
1. Sample the species from within the four most sensitive genera that has the greatest
bioaccumulation potential.
2. If no species are present from the four most sensitive genera, sample the species with the
greatest bioaccumulation potential.
3. If no species are present from the four most sensitive genera and if all species have
similar bioaccumulation potential, sample the species from within the most sensitive
genera present at the site (sensitive according to the SSD from USEPA 2021a).
States and authorized tribes should begin with targeting the fish species from within the four
most sensitive genera that have the greatest bioaccumulation potential. As described above, the
SSD for the national CWA section 304(a) recommended selenium criterion determined that the
four most sensitive genera for fish reproductive effects (in decreasing order) are Acipenser,
Lepomis, Salmo, and Oncorhynchus. When selecting a fish species to sample from within these
genera, states and authorized tribes should consider the diet and exposure of all the species at the
site that are within those four most sensitive genera and select the species that has the greatest
potential to bioaccumulate selenium. For example, if a site has multiple species of Lepomis
present (e.g., Bluegill and Redear Sunfish), the state or authorized tribe should sample the
species that has the greatest bioaccumulation potential (Redear Sunfish). In the San Francisco
estuary, sturgeon are monitored not only because they are sensitive to the toxic effects of
selenium (low ECio), but also because their primary prey at that site (clams) bioaccumulate
selenium very efficiently. As a result, sturgeon receive large doses of selenium and may be more
likely to bioaccumulate selenium to levels of concern than another species. Table 3 provides a
summary of these genera (highlighting information for the specific species tested), their relative
sensitivity, their general habitat type (warm water [WW] or cold water [CW]), and their
estimated relative bioaccumulation potential based on consideration of typical diet and trophic
level. Fish that consume primarily benthic organisms will tend to exhibit greater selenium
bioaccumulation than fish that feed higher in the water column at the same trophic level
(Schneider et al. 2015, Simmons and Wallschlager 2005). Table 3 also provides a representative
list of species, that are within the same genus as the tested sensitive species, and that could be
considered as surrogates for tissue collection. A more comprehensive list of these surrogate
species, along with details about relevant characteristics and occurrence is presented in Appendix
D.
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If no species from the four most sensitive genera are present at the site, then the state or tribe
should target the fish species with the greatest bioaccumulation potential. As stated above,
bioaccumulation potential will be predominantly determined by the diet of the species.
Composite trophic transfer factors can provide a numeric representation of bioaccumulation
between a consumer and its diet and help inform the decision about which species to sample.
If all species that are present at a site have similar diets and bioaccumulation potential, then the
state or tribe should target the most sensitive species. This will be the species with the lowest
EC 10. If the EC 10 of a particular species is unavailable, sensitivity can be estimated from the ECio
of a closely related taxon.
In addition to sensitivity and bioaccumulation potential, there are a number of factors that should
be considered when identifying appropriate fish species for collection. The following
summarizes some key points for consideration:
1. White sturgeon (and available surrogates) are distributed in large river systems in the US
and among the most sensitive genera (based on available data). These species are
typically sampled by specialized monitoring programs (e.g., USFWS and NOAA-
NMFS). Coordination with these existing programs may provide for expanded sampling
opportunities or the use of existing selenium fish tissue data. Several species and specific
populations of species within the Acipenser genus are federally listed species under the
Endangered Species Act and may not be appropriate to sample. USFWS, NOAA-NMFS,
and appropriate state agencies should be consulted before sampling any federal or state
listed threatened or endangered species.
2. Bluegill, and the related sunfish species in the genus Lepomis are widely distributed in
WW habitats, while trout species (particularly Rainbow and Brown trout) are widely
distributed in CW habitats. These species are frequently targeted by monitoring programs
in states and tribal lands with WW and CW habitats, respectively, offering a possible
opportunity for leveraging these existing sampling programs for the collection of tissue
for selenium analysis.
3. Smaller WW and CW systems (e.g., wadeable streams), which are not typically targeted
by state fish tissue contaminant monitoring programs, are often dominated by cyprinid
(minnow) species and may represent a source of fish tissue for selenium sampling in
water bodies where other species may not be present. Some of these species are shown in
Table 3 and a broader range of these species are shown in Appendix D. Given the large
number of minnow genera and species and the diversity of their trophic strategies and
habitats, the sensitivity and bioaccumulation potential for individual members of this
diverse group must be considered when evaluating a candidate species for consideration
in tissue sampling. However, state biomonitoring programs typically sample these waters
for IBI metrics, and their expertise and sampling program could be leveraged to target
species and obtain representative samples.
4. Although generalizations can be made about the potential for bioaccumulation within fish
species, when developing a sampling plan, the potential for bioaccumulation should be
considered for the specific area being evaluated. Potential for bioaccumulation within any
given species can vary significantly with location-specific factors, including prey type
and availability and the nature of selenium distribution in the environment.
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5. There are a number of species for which toxicity data are not available, but for which
dietary information allows us to characterize the potential for selenium bioaccumulation.
Some of these species are collected as target species in state monitoring programs and
could be considered to characterize selenium tissue concentrations in the absence of
sensitive species, if available data indicates these species are bioaccumulative.
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Table 3. Recommended Fish Target Species for Collection Based on Selenium Sensitivity and Bioaccumulation Potential
Bioaccumulation
Sensitivity Ranking
(Based on Egg-
Ovary ECio)
Genus, Common
Name
Habitat
(WW/CW)
Expected Relative
Bioaccumulation
Potential
Adult Diet
Trophic
Level
Additional Representative Surrogate
Species**
1
Acipenser, White
Sturgeon*
WW
Medium-High
Invertivore
Piscivore
Molluscivore
TL3/TL4
Shortnose Sturgeon*, Lake Sturgeon*
2
Lepomis, Bluegill
WW
Medium
Invertivore
Piscivore
TL3
Pumpkinseed*, Redear Sunfish*, Green
Sunfish*, Redbreast Sunfish*, Longear
Sunfish, Wannouth, Orangespotted Sunfish,
Redspotted Sunfish, Bantam Sunfish,
Northern Longear Sunfish, Spotted Sunfish
3
Salmo, Brown Trout*
CW
Medium-High
Invertivore
Piscivore
Molluscivore
TL3/TL4
None
Oncorhynchus,
Rainbow Trout
CW
Medium-High
Invertivore
Piscivore
TL3/TL4
None
4
Oncorhynchus,
Cutthroat trout
CW
Medium
Invertivore
TL3
None
5
Micropterus
Largemouth Bass
WW
Medium - High
Invertivore
Piscivore
TL4
Smallmouth Bass, Spotted Bass, Redeye Bass
WW: Satinfin Shiner, Red Shiner, Golden
Shiner*, Bull Chub*, Creek Chub, Roundtail
Chub, Thicklip Chub*, Striped Shiner, Central
Stoneroller, Blacknose Dace, Speckled Dace,
Cutlips Minnow*, River Darter*, Arkansas
Darter*
Not Ranked
Pimephales
Fathead Minnow***
WW
Low-Medium
Herbivore
Invertivore
TL2/TL3
CW: Redside Shiner, Peamouth Chub,
Mottled Sculpin
WW = warm water, CW = cold water, TL = trophic level
* Fish species that consume mollusks (clams, mussels, snails) as part of their diet and are anticipated to have relatively high bioaccumulation potential. For
brown trout, molluscivory is incidental and will likely only be significant on a site-specific basis where mollusks are abundant.
** Species are surrogates for sensitivity based ontaxonomic relationships.
*** Fathead minnow is a surrogate for small bodied fish species inhabiting wadeable streams.
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Along with sensitivity and bioaccumulation, it is also important to consider how a species'
habitat preferences, feeding regimes, and/or home ranges will affect their selenium exposure.
Species with smaller home ranges may be at risk of greater selenium exposure if the elevated
selenium is localized to their home range or their prey's home range. Species with larger home
ranges may not represent local selenium exposure. States and authorized tribes should target
species with home ranges that closely match the site being evaluated, so that the fish reflect
exposure to selenium at that particular site. Local fish biologists may be able to help states and
authorized tribes identify species' habitat preferences, feeding regimes, and home ranges. If
possible, migratory species and highly mobile species should be avoided. Highly mobile fish
species such as potamodromous and anadromous species could travel back and forth between
areas with low and elevated selenium concentrations, resulting in variable selenium tissue
concentrations (Beatty and Russo 2014). It is possible that typical selenium exposure
concentrations of migratory adults would be lower than concentrations at rearing grounds,
therefore these fish may not reflect selenium concentrations that other fish species would
experience at their time of spawning. Given this issue, resident species should be the first choice
when selecting a target species. Recently stocked fish should also be avoided, regardless of
species, since their residence time before sampling may be too short to provide a representative
sample. EPA recommends speaking with local fish and game authorities to understand stocking
frequency in waters where fish are being sampled for selenium analysis.
If migratory or highly mobile species must be sampled, then EPA recommends that sampling
plans account for the life history of these species so that the correct locations for sampling within
a watershed are selected. Before sampling these species, knowledge about the migratory extent
of these species and the time spent in each location should be known so that the influence of
selenium at each habitat location can be accounted for. EPA recommends consulting local fish
biologists (state or academic) for information about the migratory patterns of local fish
populations. If Pacific anadromous species are selected as target species to be used for sampling,
EPA recommends that states and authorized tribes sample the whole-body of juveniles (smolts)
and compare the concentration to the whole-body criterion element. This recommendation is due
to the lack of selenium exposure to adult salmonids from freshwater prior to reproduction (see
section 6.4.1.1 in USEPA 2021a).
One or more species that are sensitive to selenium (e.g., Bluegill, Rainbow Trout, Brown Trout)
are commonly present in water bodies. However, if they or species that potentially
bioaccumulate high levels of selenium are not available in sufficient numbers to sample, then
other species that are available in sufficient numbers may be used for fish tissue monitoring,
including species known to be tolerant to selenium. These selenium tissue samples can still be
compared to the appropriate tissue criterion elements (see Table 1), which are designed to be
protective of the entire aquatic community and can still be used to make an assessment decision.
In addition, if fish tissue data were collected for an alternate purpose from other fish species than
the ones recommended in this section, that data can also be used for an assessment decision.
As there are a large number of considerations involved in the selection of a target species, EPA
recommends that sampling teams develop a sampling priority plan before going into the field.
This plan should start by identifying the species and factors that will increase selenium exposure
at a site. From there, an initial target species should be selected and any decisions about sampling
locations can be made. The plan can then identify a prioritized list of species that the state or
authorized tribe will sample if the initial target species is not present in sufficient numbers. EPA
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recommends that the plan also include what type of sampling gear is required for the collection
of each species. In addition, the plan should specify if collection permits are required for fish
tissue sampling, and if so, include instructions for acquiring them before the sampling event.
Having a clear plan will ensure that the fish collected will provide the most representative data of
selenium conditions at the site.
States and authorized tribes may want to limit the number of target species that are sampled
within their state or tribal waters. The use of a limited number of target species allows for the
comparison of fish contaminant data among sites over a broad geographic area. It is difficult to
compare contaminant monitoring results within a state or tribe or among states or tribes unless
the data are from the same species because of differences in habitat, food preferences, and rate of
contaminant uptake among various fish species. However, it is impracticable to sample the same
species at every site. Limiting the number of species collected across a state allows for the
comparison of contaminant data from across a state or region. Given this, EPA recommends that
states and authorized tribes evaluate the range of sensitive species with high bioaccumulation
potential across their state or tribal waters and determine which ones may be able to be sampled
at multiple locations within the state or tribal lands.
If a state or authorized tribe is sampling fish tissue for the development of a site-specific water
column criterion element, they may want to expand their sampling to include multiple species to
better understand the system at their site. Sampling species that have high bioaccumulation
potential, as well as species with high sensitivity to selenium, could provide a more complete
picture of selenium dynamics at the site.
Lastly, care should be taken to avoid sampling threatened or endangered species when selecting
a target species. For example, although Acipenser, Salmo, and Oncorhynchus are three of the
four most sensitive genera, many species within these genera are threatened or endangered and
thus are not suitable for sampling. Before sampling from these genera and other genera with
federally listed species, EPA recommends speaking to local fish biologists to ensure that the
target species is not threatened or endangered and to confirm that the population is healthy
enough to withstand the sampling pressure. When conducting monitoring to ensure the
protection of a federally listed species, states and authorized tribes should target surrogate
species that have similar taxonomy (preferably at the genus level), diets, and trophic levels.
Species with similar taxonomy, diets, and trophic levels should have similar selenium sensitivity
and bioaccumulation as the threatened or endangered species. If a taxonomically similar
surrogate is not present, then states and authorized tribes should target a species with a similar
diet and trophic level.
2.4 Sampling Locations
Several factors should be considered when selecting where fish should be sampled (to be
analyzed either individually or as a composite) to accurately characterize the concentration of
selenium at a site of interest. The spatial extent of the site needs to be defined and the factors that
may affect selenium variability throughout the site need to be identified so that they can be
considered in the design of the sampling plan. The selection of a site and how its boundaries are
defined will be influenced by the objective of the monitoring and by past monitoring activities
(see section 3.0 Leveraging Existing Fish Tissue Monitoring Programs and Sample Design). The
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factors informing the site definition and the subsequent selection of sampling locations will vary,
and may include:
• monitoring objectives (e.g., assessment, site-specific selenium studies);
• water body type and site hydrology (lotic vs. lentic);
• water body size;
• selenium sources and location of sources;
• aquatic habitat variability; and
• physical barriers to fish movement.
These factors (and potentially others) will influence the definition of the site boundaries,
decisions about where fish are collected from within the site, and decisions about how many fish
need to be collected at the site. Discussed below are some of the factors that EPA recommends
considering with site and sample location selection, but particular situations may warrant the
consideration of other important factors.
2.4.1 Water Body Type
Selenium concentrations and bioaccumulation patterns are different in lotic (flowing waters such
as rivers and streams) versus lentic (very slow moving or still waters such as lakes and
reservoirs) environments. Water residence time is typically shorter in lotic systems than in lentic
systems, and subsequently, aquatic organisms living in lentic systems tend to bioaccumulate
proportionately more selenium than organisms living in lotic systems (ATSDR 2003; EPRI
2006; Luoma and Rainbow 2005; Orr et al. 2006; Simmons and Wallschlagel 2005). In addition,
lentic water bodies tend to have greater reducing conditions (conditions that lead to reduction
reactions and reduced ionic species of selenium such as selenite) which create an environment
where selenium accumulates in sediment more readily and may also lead to higher
bioavailability in the water column (Luoma and Rainbow 2008, Simmons and Wallschlagel
2005). Benthic organisms in lentic systems can then be exposed to higher concentrations of
selenium in the sediment, leading to increased bioaccumulation potential in other organisms
feeding on the benthic organisms (Simmons and Wallschlager 2005, Orr et al. 2006). Hillwalker
et al. (2006), for example, found that the body burden concentrations of selenium in insects
within similar taxa were up to seven times greater in lentic systems than lotic systems within the
same watershed.
When sampling fish, consideration should be given to the different flow characteristics of the site
that is being sampled along with the locations where fish are feeding and obtaining their
selenium body burdens. Some areas of a lotic site may have lentic characteristics and vice versa.
For example, some rivers may have slow moving pools or backwaters that have characteristics
similar to lentic environments. Human-made lakes and reservoirs may have some features that
are intermediate between typical lotic and lentic systems. For example, reservoirs tend to be
longer and narrower than natural lakes, and generally have a shorter water retention time than a
natural lake of comparable volume (Thornton et al. 1990). When sampling sites, attempts should
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be made to sample all habitat types to appropriately characterize the range and distribution of
selenium concentrations at a site.
2.4.2 Water Body Size
Generally speaking, the variability of selenium within resident fish populations would be
expected to be low when the spatial and temporal variability of selenium concentrations across
all compartments of the ecosystem are low (e.g., water column, sediment, etc.). As the area of a
site increases, the spatial and temporal variability is expected to also increase, thus increasing the
number of samples needed to characterize the selenium concentrations in the resident fish
populations. If the water body is sufficiently large that sub-populations are expected to be
present (potentially applicable to large reservoirs), it could be advantageous for the sub-
populations to be represented separately in the dataset.
2.4.3 Site-specific Studies for Water Column Translations
If a site-specific water column criterion element is being developed, a study should be designed
that captures data which appropriately reflects the site (e.g., captures spatial, temporal, and
habitat variability). To support a site-specific water column translation, data beyond what is
necessary for other CWA implementation purposes is typically required (e.g., additional
sampling locations, sampling times, species of fish, and/or selenium measured in multiple
matrices). The extent of the sampling and type of data collected will depend on the size and
complexity of the site. It will also depend on whether there are any discharges of selenium into
the site. A "site" may be a state, region, watershed, water body, segment of water body, category
of water (e.g., ephemeral stream), etc. Regardless of how the site is defined, the site-specific
water column translation should be derived to provide adequate protection of aquatic life for the
entire site, including both areas upstream and downstream of a discharge if one is present at the
site. To assure protection for aquatic life throughout the entire site, fish should be sampled from
locations where selenium is expected to bioaccumulate the most (areas of the site with more
lentic properties and areas where selenium may be elevated due to source contributions). In
addition to sampling from the area of greatest exposure, agencies may want to sample fish from
various locations in the site to understand the dynamics of selenium within that site. With that
knowledge, the site-specific water column translation can be designed to be protective of the
most vulnerable fish community. When the area of interest is a segment of a water body, it is
important to understand how the segment is characterized in the state or tribal WQS, the
representativeness of the partial segment to the regulatory segment as a whole, as well as its
relation to downstream segments that may support more sensitive fish species (e.g., lower ECio
or threatened and endangered species) than the immediate area of interest. In these situations, the
sampling may include fish populations in the immediate area of interest and the downstream
water body.
Additional information related to sampling fish tissue to support a site-specific water column
translation can be found in Appendix K of Aquatic Life Ambient Water Quality Criterion for
Selenium - Freshwater 2016 (USEPA 2021a) and in Technical Support for Adopting and
Implementing EPA's 2016 Selenium Criterion in Water Quality Standards, Draft (USEPA
2021c). One example of a method for conducting a site-specific water column translation can be
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found in the Draft Translation of Selenium Tissue Criterion Elements to Site-Specific Water
Column Criterion Elements for California Version 1, August 8,2018 (USEPA 2018). EPA
recommends engaging with EPA regional staff early in the development of a site-specific water
column translation to discuss study design and data needs.
2.4.4 Point Sources
When selecting sampling locations, samplers should consider where and how selenium is
entering a water body and determine whether exposure is relatively equal throughout the water
body or if some sections of the water body have greater exposure. The sampling objectives will
provide direction on how known point sources (e.g., discharge, tributary with elevated selenium,
irrigation return canal, groundwater discharge) and any associated mixing zones should be taken
into consideration when collecting fish tissue samples. When the objective is to collect data to
support assessment decisions, the goal is to measure the mean selenium concentration in the
target population throughout the sampling reach. Therefore, when a point source is located
within the defined sampling reach, there is no reason to avoid sampling fish from areas of
incomplete mixing resulting from a discharge or tributary. Given the mobility of many fish taxa,
it is reasonable to expect that fish freely move in and out of areas of incomplete mixing when the
conditions do not elicit an avoidance response (e.g., due to chemical or temperature gradients). In
some discharge situations, fish can be attracted to the effluent and spend a significant portion of
their time in the area of incomplete mixing. Also, depending on their life history, some fish
species have a limited mobility range and may spend more time in the area of incomplete mixing
if it overlaps with their territory, breeding grounds, or feeding grounds. Ultimately, jurisdictions
should consider and document if there are any reasons to avoid tissue collection from a location
adjacent to a known point source prior to sampling (e.g., conditions are not representative of the
rest of the segment).
When the sampling objective is to characterize the contribution of selenium that a known point
source is making to the water body, samples collected upstream and downstream of the point
source should be assessed independently (i.e., not composited or averaged). The downstream
sampling reach should be large enough to include samples collected within and downstream of
areas of incomplete mixing to characterize the range of bioaccumulation potential in the tissue
samples as the water column concentrations decrease. One way to do this would be to collect fish
and water samples at regular intervals from the discharge to observe how both decrease
downstream of the discharge. It is important to understand the hydrology in the system as this
will influence the range and direction of transport of selenium from the discharge source to other
portions of the water body/site. For more information on considerations related to selenium
sources and the locations of those sources, see section 2.1 in Aquatic Life Ambient Water Quality
Criterion for Selenium-Freshwater 2016 (USEPA 2021a).
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3.0 Leveraging Existing Fish Tissue Monitoring Programs and Sample
Designs
3.1 Augmenting Existing Fish Tissue Monitoring Programs
Many states and authorized tribes have existing fish tissue monitoring programs that can be
leveraged to collect fish tissue data to assess against the fish tissue criterion elements of the
national CWA section 304(a) 2016 recommended selenium criterion. In 2010, forty-five states
monitored chemical contaminants in fish tissue to assess risks to human health. Twenty-eight
states identified selenium as a contaminant in their human health monitoring programs (USEPA
2011). These states can potentially modify their current programs to not only assess human
health risks, but also assess attainment of the aquatic life selenium criterion. The design of an
agency's existing fish tissue monitoring program will likely drive its approach to selenium
monitoring. Agencies should evaluate how current sampling and analytical protocols can be
modified to meet both the objectives of monitoring for risk to human health and aquatic life
protection. Case studies are provided in the following sections as examples of programs that
might have the capacity and framework to augment their existing monitoring strategies to
include fish tissue monitoring for the selenium aquatic life criteria.
3.1.1 Consistency with Existing Programs
EPA recommends evaluating current fish tissue monitoring programs to determine how they can
be augmented to implement the national CWA section 304(a) recommended selenium criterion.
To the extent possible within a state or tribal program, EPA recommends that fish tissue
monitoring for the selenium aquatic life criterion should be consistent with the state's current
fish tissue monitoring practices regarding spatial and temporal considerations, species collected,
and sample type collected. In this way, logistical modifications to a state's fish tissue monitoring
program can be minimized. Muscle tissue is the most common type of sample collected and
analyzed by monitoring programs. Less frequently states and authorized tribes collect and
analyze whole-body samples. To maximize efficiency, a portion of these samples can be
submitted for selenium analysis. States or authorized tribes will realize cost efficiencies by
choosing to use whole-bodies or fillets that are already being collected for an existing monitoring
program.
When utilizing existing sampling programs that are designed for human health protection to
assess selenium levels for protection of aquatic life, states and authorized tribes should recognize
the potential limitations of these data. That data may not represent areas most likely to be
contaminated by selenium, most relevant time periods for sampling, or most appropriate species.
Where deviations from existing state or tribal programs are necessary due to spatial or temporal
considerations or species/sample type, these can potentially be accommodated by leveraging
expertise and logistical assistance from other agencies with existing fish tissue monitoring
programs. Since the selenium criterion applies to ecological risk and not human health,
monitoring agencies could evaluate their target species list and determine if they include
appropriate species for assessing selenium risk to aquatic life. See the discussion in section 2.3
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about selecting target species and see Aquatic Life Ambient Water Quality Criterion for Selenium
- Freshwater (USEPA 2021a) for more information about species' sensitivity and
bioaccumulation potential.
A survey conducted in 2010 reported that 40 state agencies conduct fish sampling at regular
intervals, and several conduct statewide, rotating basin sampling programs over a multi-year
period (USEPA 2011). Many states and authorized tribes may be able to utilize their current
tissue sampling programs to monitor for the selenium criterion as well. Agencies could monitor
state- or basin-wide, and track progress in individual basins relative to other areas. Regular
yearly sampling could be conducted, with intensified sampling in targeted basins as needed (see
Table 4 for several documents that provide guidance for sampling and survey designs). Several
states use a probabilistic survey design to select sampling sites. This type of sampling design can
produce estimates that represent the condition of the whole watershed, and an estimate of
random spatial variability (USEPA 2000). Probability-based sampling provides the basis for
estimating the resource (i.e., fish population(s)) extent and condition, for characterizing trends in
resource extent or condition, and for representing spatial patterns, all with known certainty
(USEPA 2009). Additional or more targeted sampling approaches may be needed in areas where
elevated selenium is associated with a known point of discharge. The case study below presents
the Kansas Department of Health and the Environment's (KDHE) fish tissue monitoring
program, which uses several designs for selecting sites. Based on the information available, it is
likely that a state or authorized tribe with a similar program could take advantage of their current
sampling strategy to perform screening level selenium analysis throughout their state or tribal
area. Where selenium is already a primary parameter of interest, the state or authorized tribe may
have the data to support more intensive studies in certain water bodies.
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CASE STUDY: The Kansas Department of Health and the Environment
The Kansas Department of Health and the Environment (KDHE) currently collects fish samples
annually from 30-50 fixed and rotating stations. The KDHE selects sites based on targeted, census,
and probability-based sampling designs. Specific sub-program objectives determine the numbers,
species, and sizes of fish collected from a particular water body, and the tissues and parameters of
interest (http://www.kdheks.gov/befs/fish tissue monitoring.htm).
Highlights (KDHE 2013):
• Whole fish, muscle, muscle plugs, or other specific tissues were collected for different
programs.
• Selenium was a primary parameter of interest.
• Specific tissues (such as egg-ovary) were analyzed for specific chemicals of concern known to
accumulate in certain organs.
http://www.kdheks.gov/environment/qmp/download/Fish Tissue Part III.pdf
This program is an example of an existing fish sampling program that could be enhanced to collect
data for the implementation of the selenium criterion.
3.1.2 Temporal Considerations
Various temporal considerations will influence fish tissue monitoring strategies for selenium.
These can include considerations related to the ecology of the fish (e.g. species' spawning
season) or to abiotic environmental factors (e.g. weather conditions and river flows). Temporal
considerations will influence decisions regarding which tissue type is sampled: egg-ovary,
whole-body, or muscle tissue. For example, most fish species that are synchronous spawners
spawn in the spring, making spring the prime season to sample egg-ovary tissues, yet sampling
for health advisories is typically done in the fall when concentrations of contaminants are highest
in muscle tissue (fillets). Agencies will need to consider their resources and determine which
tissue type they would like to sample and at what time of year. If agencies plan to sample egg-
ovary tissue, they should plan to sample right before spawning. If an agency plans to conserve
resources and sample for both fish consumption advisories and the selenium criterion at the same
time, whole-body or muscle tissue should be sampled outside of species-specific pre- and post-
spawning windows. In this case, muscle (or whole-body) tissue can be composited and evaluated
for the selenium aquatic life criterion in addition to contaminants of interest for fish consumption
advisories. If the agency has information indicating that there may be seasonal differences in
whole-body or muscle tissue concentrations, then agencies should plan to sample during the
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season when the highest selenium concentrations are expected. Agencies may want to sample
spring spawners in late summer or fall to avoid the potential for underestimating selenium body
burdens. Selenium body burdens can be decreased directly post-spawn due to the selenium
depuration from whole-body or muscle tissue via the maternal transfer of selenium to eggs and
the subsequent release of eggs to the environment. If sex can be determined in the field, agencies
may want to target male fish to avoid this possibility.
For egg-ovary tissue sampling, EPA recommends that agencies with fish tissue monitoring
responsibilities consult with local fisheries biologists to determine the appropriate time for
sampling specific species in their region in order to capture the specimens in their pre-spawning
phase. These regional experts will be familiar with the local species and are able to use their best
professional judgment to determine which species are appropriate for egg-ovary sampling and
the appropriate sampling period based on spawning season.
3.1.3 Spatial Considerations
Monitoring agencies generally target high-use fishing areas, areas of special concern, and areas
of suspected contamination (such as water bodies where fish advisories have been issued), when
selecting sites for sampling fish tissue (USEPA 2011). As current fish tissue monitoring
programs are typically designed to specifically address the risk to human health from fish
consumption, these programs predominantly sample locations where fishing is common. This
may lead to mostly sampling lakes and higher-order streams. States and authorized tribes using
this sampling design should consider if these existing programs will adequately capture water
bodies impacted by point and non-point sources of selenium and potential areas of selenium
contamination. If not, agencies may want to modify sampling designs to target such areas for
sampling.
Some states and authorized tribes may incorporate fish tissue sampling for selenium into a
statistical survey designed to understand the distribution of tissue concentrations across the state
or tribal lands. The underlying geology of a region may produce elevated selenium
concentrations in certain areas and make nearby waterbodies prone to selenium bioaccumulation,
particularly if anthropogenic activities increase the release of selenium into the system. This
should be kept in mind when selecting sites, and when analyzing data from these areas (Beatty
and Russo 2014) (See USGS map of selenium concentrations in soils and stream sediments:
https://mrdata.usgs.gov/geochem/doc/averages/se/usa.html)).
Additional sampling locations may need to be added to a current monitoring program that are
outside of areas that are typically targeted due to fishing use when sampling for the assessment
of the selenium aquatic life criterion. For example, mine runoff may elevate selenium
concentrations in headwater streams, which may not be normally targeted for fish tissue
monitoring. Agencies should also consider a species' home range in relation to the location of a
known selenium source (e.g., the migratory patterns of a certain species versus the location of a
power plant on a reservoir). It is also important to consider the relationship of an upstream
source to downstream habitats, particularly when downstream habitats have characteristics that
will lead to greater selenium bioaccumulation (e.g., lentic systems). Monitoring plans may need
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to be adjusted to reflect the species of fish available in a water body (e.g., small streams),
temporal issues (e.g., spring flood/safety, low flow), and the types of appropriate sampling gear.
The monitoring strategy in EPA's Fish Advisory Guidance Volume 1 (USEPA 2000) discusses
two tiers of studies used to identify locations where fish consumption advisories may be needed.
Information from these studies may be utilized to develop selenium specific monitoring
programs for the assessment of the aquatic life criterion. Tier 1 studies are screening studies that
evaluate a large number of sites for chemical contamination with few samples per site. These
would be most useful for water bodies, regions, or states where there are no known or expected
selenium problems. Screening studies can help states and authorized tribes identify those sites
where selenium concentrations are elevated relative to other water bodies. Information from
screening studies can be used to prioritize water bodies for future monitoring, thus enabling
resources to be used more efficiently. For example, water bodies with fish having low selenium
concentrations may be monitored less frequently in the future, while water bodies with fish
having selenium concentrations at or near the tissue criterion elements may be prioritized for
more frequent or more intensive monitoring. In addition, data collected during these screening
studies can be used to inform assessment determinations for the waters where the samples were
collected.
Tier 2 studies are intensive studies of areas identified as potential problems in screening studies.
The purpose of a Tier 2 study is to determine the magnitude of chemical contamination in
sensitive fish species, and to assess the geographic extent of the contamination. If a Tier 2 study
is being conducted for selenium, fish species from a sensitive genus with high bioaccumulation
potential should be sampled either in addition to or in place of sensitive species. Agencies will
typically use Tier 2 studies to determine the overall magnitude and variability of a specific
contaminant that was found at elevated levels during a Tier 1 study. In many areas, selenium
sources have been well characterized; in these areas a screening study may not provide any
additional information that would change the course of the investigation. At these sites, it may be
most logical to move directly to an intensive study designed to capture the magnitude and
geographical extent of the selenium contamination in fish tissue. These studies may be helpful as
a basis for developing a site-specific water column criterion element, if necessary.
3.2 Existing Resources and Information
3.2.1 Available Expertise
Within each state or authorized tribe, the agency that develops the WQS and the agency that
typically conducts fish sampling may not be the same. When designing sampling plans to assess
the selenium aquatic life criterion, agencies with experience in the development and execution of
fish sampling programs can be consulted to aid in designing an effective fish tissue monitoring
plan. State agencies should also determine whether there is any overlap in current sampling
efforts. Various state (e.g., Department of Natural Resources) and federal agencies (e.g.,
National Oceanic and Atmospheric Administration - National Marine Fisheries Service, United
States Fish and Wildlife Service [USFWS], United States Geological Survey [USGS], EPA)
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have expertise in fish sampling, biology, and ecology, and may be able to provide assistance with
designing a sampling plan.
All states and most authorized tribes and interstate commissions have established biological
assessment programs, and most have fisheries biologists and managers. This should provide the
capacity to establish or modify existing fish tissue monitoring programs to facilitate
implementation of the fish tissue-based criterion elements in the national CWA section 304(a)
recommended selenium criterion. In addition to individual state and tribal agencies and local
expertise, federal (e.g., USFWS) and state resource agency collaborations could be used as
necessary to fill in data gaps and provide supporting data. By using all available resources for
information and expertise, monitoring agencies should be able to:
• Identify potential sites/locations, water bodies, and watersheds for selenium sampling
beyond the coverage of current monitoring programs
• Design an appropriate monitoring strategy (including selection of tissue type and sample
type (i.e., individual or composite samples))
• Select target species
• Identify pre-spawning periods
• Procure analytical support
The case study below presents Minnesota's Fish Contaminant Monitoring Program, which is
implemented through a collaborative partnership of four state agencies to maximize available
expertise. Based on the available information, a state or authorized tribe with a similar
collaborative program could take advantage of their joint resources to devise the most efficient
approach for adding selenium to their current monitoring strategy. They could also use their
extensive database to determine where to conduct more intensive studies.
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CASE STUDY: Minnesota's Fish Contaminant Monitoring Program
Minnesota's Fish Contaminant Monitoring Program is implemented through a partnership of
Minnesota Departments of Natural Resources, Health, and Agriculture and the Minnesota
Pollution Control Agency (MPCA). The data are used to issue fish consumption advisories,
identify impaired waters, research mercury cycling, and document long term trends for PCBs and
mercury.
Highlights (MPCA 2008, P. McCann, personal communication, May 7, 2018):
• Approximately 130 lakes and river sites are sampled annually.
• The Fish Contaminant Monitoring Program database contains over 52,000 data records.
• As of 2016, the program has sampled 1,410 lakes of the estimated 5,500 fishing lakes in the
state.
This program is a robust example of how interagency cooperation can maximize available
expertise, resources, and cost effectiveness.
https://www.pca.state.mn.us/sites/default/files/p-p2s4-05.pdf
3.2.2 Existing Guidance
In 2000, EPA published guidance related to monitoring of contaminants in fish called Guidance
for Assessing Chemical Contaminant Data for Use in Fish Advisories, Vol 1: Fish Sampling and
Analysis (USEPA 2000). EPA's Fish Advisory Guidance Volume 1 discusses study design
considerations and the major protocols that must be specified for fish collection, such as site
selection, analyte screening values, sampling times, sampling type, and QA/QC.
EPA's Fish Advisory Guidance Volume 1 also contains information on monitoring strategies,
field procedures, sample number, sample collection, and sample handling which can be helpful
to state and tribal programs monitoring for implementation of the fish tissue components of
EPA's aquatic life selenium criterion recommendations. EPA's Fish Advisory Guidance Volume
1 provides useful information on the collection of whole-body and muscle tissue samples.
Specifically, section 7.2.2 of EPA's Fish Advisory Guidance Volume 1 (USEPA 2000) includes
detailed directions for preparing muscle and whole-body samples. The limitation to this guidance
is that it was developed specifically for assessing human health risks associated with
consumption of fish and shellfish. As a result, there are aspects of implementing the aquatic life
selenium fish tissue-based criterion that are not specifically addressed by EPA's Fish Advisory
Guidance Volume 1 (e.g., fish egg-ovary sampling).
Data collected through monitoring for criterion assessment will be used differently than data
collected for fish advisories. In the waterbody criterion assessment context, once a criterion
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element is exceeded, the water body is considered impaired (and placed on the state's or
authorized tribe's CWA section 303(d) list), and a likely next step would be additional
monitoring for a TMDL (to identify sources) or site-specific criterion. Data from intensive fish
advisory studies, like Tier 2 studies described in EPA's Fish Advisory Guidance Volume 1,
might help to support TMDL development for those waters where one or more of the fish tissue
criterion elements are exceeded.
In addition to EPA's Fish Advisory Guidance Volume 1, EPA and other stakeholders have
produced numerous documents on bioassessment techniques. Specific sections of these
documents contain information that may be helpful for developing guidelines for sampling fish
for selenium fish tissue analysis, particularly for species like cyprinids which are not typically
targeted by state monitoring programs. For example, Rapid Bioassessment Protocols for Use in
Streams and Wadeable Rivers: Periphyton, Benthic Macroinvertebrates, and Fish - Second
Edition Chapter 3 (Barbour et al. 1999) provides guidance and information on the elements of
biomonitoring, including seasonality and methods for fish collections. A selection of
recommended documents for additional guidance is presented in Table 4.
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Table 4: Recommended Documents for Additional Guidance
Title
Author
Link
Guidance for Assessing Chemical
Contaminant Data for Use in Fish
Advisories, Vol 1: Fish Sampling and
Analysis1
USEPA
2000
https ://www.epa. gov/sites/production/files/2015 -
06/documents/volume 1 ,odf
Rapid Bioassessment Protocols for Use
in Streams and Wadeable Rivers:
Periphyton, Benthic Macroinvertebrates,
and Fish - Second Edition
Barbour et
al. 1999
https://www.epa.aov/sites/production/files/2019-
02/documents/rapid-bioassessment-streams-
rivers-1999.pdf
Field Sampling Plan for the National
Study of Chemical Residues in Lake Fish
Tissue1
USEPA
2002a
htto ://www.eoa. aov/sites/oroduction/files/2015-
07/documents/fish-studv-fieldplan.pdf
The National Study of Chemical Residues
in Lake Fish Tissue (Final Report)1
USEPA
2009
httos://nems.ei3a.aov/Exe/ZvPDF.cai/P1005P2Z.P
DF?Dockev=P 1005P2Z.PDF
Concepts and Approaches for the
Bioassessment ofNon-Wadeable Streams
and Rivers
Flotemersch
et al. 2006
httos://nems.ei3a.aov/Exe/ZvPDF.cai/600006KV.P
DF?Dockev=600006KV.PDF
Guidance on Choosing a Sampling
Design for Environmental Data
Collection
USEPA
2002b
htto ://www.eoa. aov/sites/oroduction/files/2015-
06/documents/a5 s-final.pdf
Spatially Balanced Survey Designs for
Natural Resources. Design and Analysis
of Long-Term Ecological Monitoring
Studies
Olsen et al.
2012
https://www.cambridae.ora/core/books/desian-
and-analvsis-of-lonaterm-ecoloaical-monitorina-
studies/spatiallv-balanced-survev-desians-for-
natural-
resources/F06C6F53022E46D694D1233782D5F
274
Spatially Balanced Sampling of Natural
Resources
Stevens and
Olsen 2004
https://cfpub.epa. aov/ncer abstracts/index, cfm/f
useaction/displav.files/filelD/13339
Application of Global Grids in
Environmental Sampling
Olsen et al.
1998
https://archive.ei3a.aov/nheerl/arm/web/html/abolse
n98.html
National Rivers and Streams Assessment
2018/19: Field Operations Manual—
Non-Wadeable1
USEPA
2019a
https://www.epa.aov/sites/production/files/2019-
05/documents/nrsa 1819 fom nonwadeable ver
sion 1.2.pdf
National Rivers and Streams Assessment
2018/19: Field Operations Manual—
Wadeable1
USEPA
2019b
https://www.epa.aov/sites/production/files/2019-
05/documents/nrsa 1819 fom wadeable versio
n 1.2 O.pdf
National Coastal Condition Assessment
2015 Field Operations Manual1
USEPA
2015
littDS ://www.et>a. aov/sites/nroduction/files/2016-
03/documents/national coastal condition assessm
ent 2015 field operation manual version 1.0 1 ,d
df
Biomonitoring of Environmental Status
and Trends (BEST) Program: Field
Procedures for Assessing the Exposure
of Fish to Environmental Contaminants
Schmitt et
al. 1999
https://www.cerc.usas.aov/pubs/center/pdfDocs/
91116.pdf
'Fishing sampling in these references are designed specifically for assessing risk to human health through fish consumption.
34
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3.2.3 Using Existing Data to Enhance Selenium Monitoring
EPA recommends considering and utilizing all available data, as appropriate, to inform and
enhance selenium monitoring. According to EPA's 2010 Fish Advisory Survey Report, 28 states
identify selenium as a contaminant in their fish monitoring program (USEPA 2011). Several
states have conducted extensive statewide assessments and could have existing selenium data.
Other organizations may also have selenium data available. For example, the Ohio River Valley
Water Sanitation Commission collects fish tissue samples for selenium analysis as part of their
Fish Consumption Advisory Program, and has data available online
(http://www.or sanco. or g/fi sh-ti s sue). National scale data sources for selenium in fish tissue
samples include EPA's 2008-2009 National Rivers and Streams Assessment (available at
https://www.epa.gov/national-aquatic-resource-survevs/national-rivers-and-streams-assessment-
2008-2009-results ) and the National Listing of Fish Advisories Fish Tissue Search database
(available at https://fishadvisorvonline.epa.gov/FishTissue.aspx). EPA also has concentration
data available from one hundred paired mercury and selenium fish fillet samples collected in
2007 (available at http://www.epa.gov/sites/production/files/2015-07/mercury-
finaldata2012.xlsx). Sample sites for this 2007 study were randomly selected from U.S. locations
where mercury advisories for fish consumption were in place at the time of sampling. Available
data can be used to conserve limited resources by providing baseline information which can
inform future collections by indicating which areas may and may not need additional monitoring.
4.0 Sample Analysis
4.1 Analytical Chemistry
Fish tissue sampling to support implementation of the national CWA section 304(a)
recommended selenium criterion will need to address many of the same analytical concerns as
those associated with other tissue monitoring programs. Various researchers have shown that
analytical results on the same population of fish can differ between studies and even within
studies. These uncertainties inherent in any sampling program can be minimized through a
rigorous study design, clear data quality objectives, meticulous QA/QC protocols, and careful
execution of the monitoring program in the field. Standardized methods should be followed in
the field to ensure the appropriate samples (have been handled, preserved, and shipped according
to protocol) are analyzed in the laboratory (Beatty and Russo 2014). Consistent analytical
methods and procedures should be used across implementation programs that are utilizing fish
tissue data. Analytical methods should be selected that are sufficiently sensitive to address study
objectives (e.g., methods with detection limits below the selenium fish tissue criterion elements
after allowing for conversion to dry weight concentrations) and minimize the number of values
that are below the MDL. Results should be reported to the appropriate significant figures for the
precision of the analytical method.
Laboratories should be selected based on relevant laboratory accreditations, strong QA/QC
protocols, and experience with using analytical methods for selenium and the fish tissue matrix.
Samples should be prepared in accordance with the tissue type. Section 7.2.2 of EPA's Fish
35
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Advisory Guidance Volume 1 (USEPA 2000) includes detailed directions for preparing muscle
and whole-body samples. Appendix A of this document includes directions for preparing egg and
ovary samples. EPA does not have approved 40 CFR Part 136 methods for measuring selenium
in fish tissue at this time. However, states and authorized tribes are not required to use EPA-
approved methods for monitoring and assessment of criteria attainment or criteria development.
Additionally, in the case of pollutants or pollutant parameters for which there are not approved
methods under 40 CFR Part 136 or methods are not otherwise required under 40 CFR Chapter I,
subchapter N or O, monitoring for activities related to permit applications, permit limits, or
permit compliance reports shall be conducted according to a test procedure specified in the
permit for such pollutants or pollutant parameters.2 In the assessment of criteria attainment and
establishment of lists of waters not attaining criteria, however, states are required to assemble
and evaluate all existing and readily-available water quality-related data and information (40
CFR 130.7(b)(5)). If a state or authorized tribe has additional statutes concerning data
acceptability or laboratory accreditation programs, then the fish tissue analytical methods
implemented by the state or authorized tribe should be in compliance with these statutes.
Before selecting a method for analysis and a laboratory to conduct those analyses, states and
authorized tribes should discuss with laboratories their MDLs for detecting selenium in fish
tissue using a particular analytical method. States and authorized tribes should confirm whether
those MDLs are for wet weight or dry weight and assure that they are sensitive enough for the
assessment of the selenium criterion or for site-specific study purposes. Table 5 presents several
analytical procedures for measuring selenium in solids and biota with MDLs that are sufficiently
sensitive for comparison to the tissue criterion elements. Exact MDLs and quantitation limits
(QL) for these methods are not provided, as those values are laboratory and project specific,
however, all the methods listed below should be sensitive down to a selenium concentration of at
least 1.5 mg/kg dw. States and authorized tribes should decide which value they want the
laboratory to use for reporting, whether they would like it to be equal to the MDL, QL, or some
alternative value that they have confidence in using for regulatory decisions. See section 4.2 of
this document for discussion about evaluating data that is below the MDL or falls in between the
MDL and the QL. Furthermore, some of the analytical methods and procedures identified in
Table 5 do not include specific QC requirements and acceptance limits. Therefore, jurisdictions
will need to work closely with the laboratory to establish appropriate requirements so that the
data meet the monitoring objectives.
2 The standard conditions of an NPDES permit (40 CFR 122.41 and 122.4(i)) require, when available, permittees use
test procedures specified in 40 CFR Part 136.
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Table 5: List of Test Procedures for Total Selenium in Solids and Biota
Method
Digestion /
Preparation in
reference
method?
Links to Methods
EPA Method 6020B1 -
Inductively Coupled Plasma -
Mass Spectrometry (ICP - MS)
No-
Recommended: 3052
(total), or 3050B
(total recoverable)
httos ://www.et>a. eov/esam/eoa-method-
6020b-sw-846-inductivelv-couoled-
Dlasma-mass-SDCCtromctrv
htft>s://www.et>a.eov/sites/i3roduction/file
s/2015-12/documents/3052.odf
htft>s://www.et>a.eov/sites/i3roduction/fi
lcs/2015-06/documcnts/cDa-3050b.Ddr
EPA Method 77421 -
Atomic Absorption, Borohydride
Reduction
No-
Recommended: 3052
(total), or 3050B
(total recoverable)
httos ://www. ena. gov/sites/Droduction/file
s/2015 -12/documents/7742.odf
(See links for digestion methods above)
USGS 1-9020-05 -
Determination of Elements in
Natural-water, Biota, Sediment,
and Soil Samples using Collision
/Reaction Cell ICP - MS
No - References 3052
(total)
Recommended: 3052
(total), or 3050B
(total recoverable)
httDs://Dubs. Lisas. ao\/tin/2006/tni5b 1/P
DF/TM5-Bl.t>df
(See links for digestion methods above)
NOAA 140.1-
Graphite Furnace-Atomic
Absorption for the Analysis of
Trace Metals in Marine
Animal Tissues
Yes - Teflon Bomb
httos://www.nemi.eov/methods/method
summarv/7185/
EPA Method 200.8, Rev 5 A1-2 -
Determinations of Trace
Elements in Waters by ICP- MS
(1994a)
Yes - Section 11.3
May also use: 3052
(total), or 3050B (total
recoverable)
httos ://\vww.cDa. ao v/s i tcs/o roduc t i o n/fi 1
es/2015-08/documents/method 200-
8 rev 5-4 1994.odf
1 These EPA methods are not included in 40 CFR Part 136 for fish tissue analysis. EPA does not currently have any 40 CFR
Part 136 methods for analyzing parameters in fish tissue.
2 Tissue samples must be digested before using this method.
Tissue samples should be homogenized and digested prior to analysis using strong acid and
either a closed-vessel microwave digestion or an open-vessel heated digestion procedure. If
samples are to be dried before homogenization and digestion, freeze drying is a good drying
technique to use to minimize selenium losses from the sample. However, undried tissues may be
homogenized and digested, and a dry weight conversion can be determined using a separate
aliquot of the homogenized tissue. The suitability of a given technique should be discussed with
the individual laboratory given its capabilities and preference. The laboratory and the agency
submitting the samples should mutually decide on a technique that meets the purposes of the
monitoring. Care should be taken to use a process that will minimize the loss of volatile
37
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selenium. Reference materials, analytical duplicates, and matrix spike samples are recommended
to determine the applicability of the selected digestion and analysis procedures.
The North American Metals Council-Selenium Work Group (NAMC-SWG) has published
comprehensive discussions of analytical concerns relevant to selenium; Ohlendorf et al. (2008)
and Ohlendorf et al. (2011). An additional NAMC-SWG document, Ralston et al. (2008),
presents guidance on analytical methods for selenium. Inductively coupled plasma mass
spectrometry is the typical method used for analyzing selenium in tissue and other matrices;
however, this method is sensitive to interferences. When using this method, these potential
interferences should be addressed. Alternative methods for analyzing selenium are discussed in
D'Ulivo (1997), Ohlendorf et al. (2008), and Ralston et al. (2008). States and authorized tribes
should choose an analytical method that is sufficiently sensitive to implement its water quality
standard for selenium or meet the site-specific study objectives.
States and authorized tribes can also adapt methods for analyzing selenium in water to measure
selenium in fish tissue, as long as the fish tissue samples are appropriately digested. In particular,
EPA Method 200.8, Rev 5.4, Determination of Trace Elements in Waters and Wastes by
Inductively Coupled Plasma-Mass Spectrometry (1994a) can easily be adapted to tissue analyses
by the addition of an appropriate digestion procedure. Additional information regarding
analytical methods for water samples can be found in Appendix L of the Aquatic Life Ambient
Water Quality Criterion for Selenium - Freshwater 2016 (USEPA 2021a). Complete
descriptions of analytical methods appropriate for analyzing selenium in different media can be
found in the National Environmental Methods Index at http://www.nemi.gov.
4.2 Data Analysis
EPA's regulations require that states assemble and evaluate all existing and readily available
water quality-related data and information for use in assessing water quality and developing their
CWA section 303(d) lists. How a state or authorized tribe plans to evaluate data should be
reflected in their assessment methodology. An assessment methodology constitutes the decision
process that a state or authorized tribe employs to determine the use attainment status of waters
in their jurisdiction. States and authorized tribes should evaluate if there is a need to update their
existing assessment methodology to account for how they plan to analyze their selenium tissue
data. The methodology should describe how selenium data and information are evaluated and
used to make water quality attainment determinations, including data quality, quantity, and
representativeness considerations. The methodology should also include any statistically based
procedures used during the assessment.
When sufficient data are available, jurisdictions may consider use of the recommended statistical
approaches in EPA's Fish Advisory Guidance Volume 1 (USEPA 2000). When comparing
contaminants to the criterion, the guidance recommends use of a one-sample t-test to statistically
compare the mean of all fish tissue data for a single species and single tissue type to the
applicable criterion. If there are concerns with meeting critical assumptions underlying the t-test
or another parametric test (e.g., normality), then a nonparametric test could be used. A
38
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nonparametric t-test alternative, such as a one-sample Wilcoxon Signed Rank test, can be used to
evaluate if the median selenium tissue concentration is greater than the applicable criterion.
Intensive studies may include the collection of fish tissue data from several locations within a
region of interest or for multiple time periods (e.g., seasons or years) from a single location, or a
combination of both. Data from intensive studies such as these may be used to perform spatial or
temporal analyses to provide information on selenium variability in a target species population.
EPA's Fish Advisory Guidance Volume 1 provides recommended statistical approaches for
comparing contaminants measured at different locations or over time (See Appendix N of
USEPA 2000). EPA recommends that states and authorized tribes consult a statistician to
determine the specific statistical tests needed for a particular dataset and choose a method best
suited to how they express their WQS. Consulting a statistician at the time of the study design
may also be useful for assuring that the appropriate data are collected to answer the desired
question.
When making assessment decisions, states and authorized tribes should consider how they will
address potential data quality concerns, such as the use of analytical results that are below the
method detection limit (MDL) and/or analytical results that are in between the MDL and the
quantitation limit (QL). These results can be largely avoided with proper quality assurance
project planning. The collection of sufficient tissue mass and use of a sufficiently sensitive
analytical method will provide results with a minimal number of values below the MDL and
between the MDL and QL. However, if a state or authorized tribe is using a dataset that includes
values below the MDL or in between the MDL and the QL, it should decide how it will evaluate
these values.
There are various conventions to deal with these measurements and the state or authorized tribe
has the flexibility to determine which is appropriate for their given situation. EPA notes that
identifying and developing approaches to statistically analyze datasets containing non-quantified
chemical concentration values (i.e., "censored data") is an active area of research and no one
method can be universally recommended (for more information see: Helsel 2005, Pleil 2016,
and, Singh and Nocerino 2002). EPA's Fish Advisory Guidance Volume 1 (USEPA 2000)
recommends using one-half of the MDL for values below the MDL in calculating mean values
(section 9.1.2). The guidance also recommends that measurements that fall between the MDL
and the QL be assigned a value of the MDL plus one-half the difference between the MDL and
the QL. EPA notes, however, that these conventions provide a biased estimate of the average
concentration (Gilbert 1987) and, where the computed average is close to the criterion, might
suggest an impairment when one does not exist or, conversely, suggest no impairment when
one does exist. As an alternative to this convention, some states, authorized tribes, and
laboratories may choose to apply what is called a "J" flag to any results reported at or above the
MDL, but below the QL. The "J" flag would indicate that the chemical is present, but the
reported value is an estimate of the true concentration since it was detected below the QL. Some
states and authorized tribes may choose to use these "J" flagged values for data analysis. EPA
used this convention for the National Study of Chemical Residues in Lake Fish Tissue, including
all the "J" flagged data in analyses of the fish tissue data (USEPA 2009).
39
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States or authorized tribes can also calculate the average of a dataset that includes values below
the MDL using other statistical methods (e.g., sample median and trimmed means) (Gilbert
1987). Singh and Nocerino (2002) have published a review of several methods for data reporting
and analyzed the potential bias each can introduce into the calculation of the mean.
One approach that a state or authorized tribe could take to ascertain the consequence of what
value is used to quantify samples below the MDL is to conduct a sensitivity analysis. In a
sensitivity analysis, the state or authorized tribe would compute the mean concentration by first
using the value of the MDL to quantify samples below the MDL and then using a zero value for
samples below the MDL. For example, if the MDL is 1.5 mg/kg dw, first the mean would be
calculated with all values below the MDL being assigned the value of 1.5 mg/kg dw. Then the
mean would recalculated with the value of 0.0 mg/kg dw being assigned to all values below the
MDL. If both calculated means are above or below the criterion, it is clear that the choice of how
to quantify samples below the MDL does not affect the decision. However, if one calculated
mean is below the criterion and the other is above, it is clear that the choice of how to quantify
samples below the MDL does affect the decision, and a state or authorized tribe may want to use
a more sophisticated approach such as the ones presented in Robust Estimation of Mean and
Variance Using Environmental Datasets with Below Detection Limit Observations (Singh and
Nocerino 2002).
All data handling conventions have advantages and disadvantages. A state or authorized tribe
should understand the consequences of which convention it uses, especially if the choice makes
a difference as to whether a water body is considered impaired or not. Furthermore, a state or
authorized tribe should be clear about which approach it used. The selected approach must be
consistent with the state's EPA-approved WQS and should generally adhere to any published
assessment method associated with them. For further discussion on handling values below the
MDL, see USEPA 2000 (section 9.1) and USEPA 2010 (section 4.3.1). In general, states or
authorized tribes should not have issues with measurements of selenium in fish tissue being
below the MDL when a sufficient mass of tissue is collected as the method sensitivities are low
enough and all fish should have selenium concentrations higher than those MDLs. Similarly,
with sufficient sample mass and appropriate analytical methods, it is unlikely that many states
and authorized tribes will have to deal with selenium measurements between the MDL and QL
for fish tissue.
Literature Cited
ATSDR. 2003. Toxicological profile for selenium. Agency for toxic substances and disease
registry. http://www.atsdr.cdc.gov/ToxProfiles/tp92.pdf
Barbour, M.T., J. Gerritsen, B.D. Snyder, and J.B. Stribling. 1999. Rapid bioassessment
protocols for use in streams and wadeable rivers: periphyton, benthic macroinvertebrates and
fish, second edition, chapter 3. EPA 841-B-99-002. U.S. Environmental Protection Agency,
Office of Water, Washington, D.C.
https://nepis.epa.gov/Exe/ZvPDF.cgi/2000400K.PDF?Dockev=200040QK.PDF
40
-------
Beatty, J.M. and G.A. Russo. 2014. Ambient water quality guidelines for selenium technical
report update. ISBN 978-0-7726-6740-3. British Columbia Ministry of Environment,
Environmental Sustainability and Strategic Policy Division, Water Protection and
Sustainability Branch. https://www2.gov.bc.ca//assets/gov/environment/air-land-
water/water/waterqualitv/water-qualitv-guidelines/approved-wqgs/bc moe se wqg.pdf
Bradshaw, C.J.A. and C.R. McMahon. 2008. Fecundity. In: Jorgensen, E.J. andB.D. Fath, (eds).
Encyclopedia of Ecology, 1st ed. Amsterdam, The Netherlands: Elsevier B.V., 1535-1543.
Chapman, P.M., W.J. Adams, M. L. Brooks, C.G. Delos, S.N. Luoma, W.A. Maher, H.M.
Ohlendorf, T.S. Presser, and D.P. Shaw. 2009. Ecological assessment of selenium in the
aquatic environment: Summary of a SETAC Pellston Workshop. Pensacola FL: Society of
Environmental Toxicology and Chemistry (SETAC).
https://cdn.vmaws.com/www.setac.org/resource/resmgr/publications and resources/selsummarv.pdf
Chapman P.M., W.J. Adams, M.L. Brooks, C.G. Delos, S.N. Luoma, W.A Maher, H.M.
Ohlendorf, T.S. Presser, and D.P. Shaw (eds). 2010. Ecological Assessment of Selenium in
the Aquatic Environment. SETAC Press, Pensacola, FL, USA.
Cizdziel, J. V., T.A. Hinners, and E.M. Heithmar. 2002. Determination of total mercury in fish
tissues using combustion atomic absorption spectrometry with gold amalgamation. Water
Air Soil Pollut. 135:355-370. https://link.springer.eom/article/10.1023/A:1014798012212
DeForest, D.K., and W.J. Adams. 2011. Selenium accumulation and toxicity in freshwater fishes.
In: Beyer, W.N., and J.P. Meador, editors. Environmental Contaminants in Biota -
Interpreting Tissue Concentrations, 2nd ed. Boca Raton, FL (US): CRC Press, pp. 185-221.
https://www.researchgate.net/publication/260139875 Environmental Contaminants in Biot
a Interpreting Tissue Concentrations Second edition by W Nelson Beyer James P Mea
dor
D'Ulivo, A. 1997. Determination of selenium and tellurium in environmental samples. Analyst
122:117R-144R.
http://pubs.rsc.Org/en/content/articlelanding/1997/an/a704759b/unauth#ldivAbstract
EPRI. 2006. Fate and effects of selenium in lentic and lotic Systems. Electric Power Research
Institute. Product ID 1005315. 104 pages.
FishBase, accessed March 1, 2016, http://www.fishbase.org/Glossary/
Flotemersch, J.E., J.B. Stribling, and M.J. Paul. 2006. Concepts and approaches for the
bioassessment of non-wadeable streams and rivers. EPA/600/R-06/127. U. S. EPA, Office of
Research and Development, National Exposure Research Laboratory, Cincinnati, OH.
https://nepis.epa.gov/Exe/ZvPDF.cgi/600006KV.PDF?Dockev=600006KV.PDF
Gilbert, R.O. 1987. Statistical Methods for Environmental Pollution Monitoring. New York:
VanNostrand Reinhold Company.
Hamilton, S.J., K.J. Buhl, N.L. Faerber, R.H. Wiedmeyer, and F.A. Bullard. 1990. Toxicity of
organic selenium in the diet to Chinook salmon. Environ. Toxicol, and Chem. 9:347-358.
http://onlinelibrarv.wilev.com/doi/10.1002/etc.562009031Q/abstract
41
-------
Helsel D.R. 2005. Nondetects and data analysis. Statistics for censored environmental data.
Hoboken: Wiley-Interscience.
Hillwalker, W. E., P. C. Jepson, and K. A. Anderson. 2006. Selenium accumulation patterns in
lotic and lentic aquatic systems. J Sci. Total. Environ 366:367-379.
http://www.sciencedirect.com/science/article/pii/S0048969706000Q76
Hitt, N. P. and D. R. Smith. 2015. Threshold-dependent sample sizes for selenium assessment
with stream fish tissue. Integr. Environ. Assess. Manag. 11:143-149.
http ://onlinelibrary. wilev. com/doi/10.1002/ieam. 15 79/full
Janz, D M., D.K. DeForest, M L. Brooks, P.M. Chapman, G. Gilron, D. Hoff, W.A. Hopkins,
D.O. Mclntyre, C.A. Mebane, V.P. Palace, J.P. Skorupa and M.Wayland. 2010. Selenium
toxicity to aquatic organisms. In: Chapman P.M., W.J. Adams, M.L. Brooks, C.G. Delos,
S.N. Luoma, W.A. Maher, H.M. Ohlendorf, T.S. Presser, D.P. Shaw(eds). Ecological
Assessment of Selenium in the Aquatic Environment. SETAC Press, Pensacola, FL, USA.
Johns, C., S.N. Luoma, and V. Elrod. 1988. Selenium accumulation in benthic bivalves and fine
sediments of San Francisco Bay, the Sacramento-San Joaquin Delta (USA), and selected
tributaries. Estuar. Coast. Shelf Sci. 27(4): 381-396.
http://www.sciencedirect.com/science/article/pii/0272771488900959
KDHE, Division of Environment, Bureau of Water, Watershed Planning, Monitoring, and
Assessment Section. 2013. Division of Environment Quality Management Plan, Part III: Fish
Tissue Contaminant Monitoring Program. Quality Assurance Management Plan, Revision 2.
Topeka, Kansas.
http://www.kdheks.gov/environment/qmp/download/Fish Tissue Part III.pdf
Luoma, S.N. and T.S. Presser. 2009. Emerging opportunities in management of selenium
contamination. Environ. Sci. Technol. 43:8483-8487.
http://pubs.acs.org/doi/pdf/10.1021/es900828h
Luoma, S.N. and P.S. Rainbow. 2008. Selenium: Dietary exposure, trophic transfer and food
web effects. In: Metal Contamination in Aquatic Environments: Science and Lateral
Management. New York, NY (US); Cambridge University Press. 573pp.
May, T.W, J.F. Fairchild, J.D. Petty, M.J. Walther, J Lucero, M. Delvaux, J. Manring, M.
Armbruster. 2008. An evaluation of selenium concentrations in water, sediment,
invertebrates, and fish from the Soloman River Basin. Environ. Monit. Assess. 137: 213-232.
https://link.springer.com/content/pdf/10.1007/slQ661-007-9742-v.pdf
Minnesota Pollution Control Agency. 2008. Minnesota's Fish Contaminant Monitoring Program.
Pollution Prevention/Sustainability Fact Sheet 4.05. St. Paul, MN.
https://www.pca.state.mn.us/sites/default/files/p-p2s4-05.pdf
Murua, H. and F. Saborido-Rey. 2003. Female reproductive strategies of marine fish species of
the North Atlantic. J. Northw. Atl. Fish. Sci. 33: 23-31.
https://iournal.nafo.int/Portals/0/2003-Vol33/murua.pdf
42
-------
Nagahama, Y. 1983. The functional morphology of teleost gonads. In: Hoar W.S., D.J. Randall,
E.M. Donaldson, (eds). Fish Physiology Academic Press, New York,233-275 pp.
National Oceanic and Atmospheric Administration (NOAA). 1998. Sampling and analytical
methods of the national status and trends program mussel watch project: 1993-1996 Update.
NOAA Technical Memorandum NOS ORCA 130. March 1998. Silver Spring, MD. 233pp.
North American Metals Council - Selenium Working Group. 2008. Selenium tissue thresholds:
Tissue selection criteria, threshold development endpoints, and potential to predict
population or community effects in the field. Washington, DC.
http://www.namc.org/docs/00043675.PDF
Ohlendorf, H.M., S.M. Covington, E.R. Byron, and C.A. Arenal. 2008. Approach for conducting
site-specific assessments of selenium bioaccumulation in aquatic systems. Washington DC
(US): North American Metals Council. http://www.namc.org/docs/00043671.PDF
Ohlendorf, H.M., S.M. Covington, E.R. Byron, and C.A. Arenal. 2011. Conducting site-specific
assessments of selenium bioaccumulation in aquatic systems. Integr.Environ. Assess, and
Manag.7(3):314-324. http://onlinelibrary.wilev.com/doi/10.1002/ieam.157/abstract
Olsen, A.R., T.M. Kincaid, Q. Payton, 2012. Spatially balanced survey designs for natural
resources. In: Gitzen, R.A., J. J. Millspaugh, A.B. Cooper and D.S. Licht. (eds.) Design and
Analysis of Long-Term Ecological Monitoring Studies. Cambridge, UK, Cambridge
University Press, 126-150. https://www.cambridge.org/core/books/design-and-analysis-of-
long-term-ecological-monitoring-studies/508A10FEE39E7E93EF07B005D06952F5
Olsen, A.R., D.L. Stevens, Jr., and D. White, 1998. Application of global grids in environmental
sampling. Computing Science and Statistics 30, 279-284.
https://archive.epa.gov/nheerl/arm/web/html/abolsen98.html
Orr, P.L., K.R. Guiguer and C.K. Russel. 2006. Food chain transfer of selenium in lentic and
lotic habitats of a western Canadian watershed. Ecotoxicol. and Environ. Safe. 63:175-188.
http://www.sciencedirect.com/science/article/pii/S01476513050Q2277
Osmundson, B. and J. Skorupa. 2011. CO-Selenium in fish tissue: Prediction equations for
conversion between whole body, muscle, and eggs. Project FFS ID: 6F50. Department of the
Interior, U.S. Fish and Wildlife Service, Region #6.
https://ecos.fws.gov/ServCat/DownloadFile/21636?Reference=23117Patil, G.P., S.D. Gore,
and C. Taillie. 2011. Composite Sampling: A Novel Method to Accomplish Observational
Economy in Environmental Studies. New York, New York (US): Springer.
Pleil, J.D. 2016. Imputing defensible values for left-censored 'below level of quantitation'(LoQ)
biomarker measurements. J. Breath Res. 10(4): 045001.
https://pubmed.ncbi.nlm.nih.gov/27753432/
Ralston, N.V.C., J. Unrine and D. Wallschlager. 2008. Biogeochemistry and analysis of selenium
and its species. Washington DC (US): North American Metals Council. 61p.
http://www.namc.org/docs/00043673.PDF
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Reinfelder, J.R., W.X. Wang, S.N. Luoma, andN.S. Fisher. 1997. Assimilation efficiencies and
turnover rates of trace elements in marine bivalves: A comparison of oysters, clams and
mussels. Mar. Biol. 129(3): 443-452.
http://wwwrcamnl.wr.usgs.gov/tracel/references/pdf/MarBio vl29p443.pdf
Saiki M.K., M.R. Jennings and W.G. Brumbaugh. 1993. Boron, molybdenum, and selenium in
aquatic food chains from the Lower San Joaquin River and its tributaries, California. Arch.
Environ. Contam. Toxicol. 24:307-319.
https://link.springer.com/article/10.10Q7/BF01128729
Saiki M.K. and T.P. Lowe. 1987. Selenium in aquatic organisms from subsurface agricultural
drainage water, San Joaquin Valley, California. Arch. Environ. Contam. Toxicol. 16:657-
670. https://link.springer.com/article/10.1007/BF01055416
Schmitt, C.J., V.S. Blazer, G.M. Dethloff, D.E. Tillitt, T.S. Gross, W.L. Bryant Jr, L.R.
DeWeese, S.B. Smith, R.W. Goede, T.M. Bartish, and T.J. Kubiak. 1999. Biomonitoring of
Environmental Status and Trends (BEST) Program: field procedures for assessing the
exposure of fish to environmental contaminants. U.S. Geological Survey, Biological
Resources Division, Columbia, (MO): Information and Technology Report USGS/BRD-
1999-0007. iv + 35pp. + appendices.
Schneider, L., W. Maher, J. Potts, A.M. Taylor, G.E. Batley, F. Krikowa, A.A. Chariton and B.
Gruber. 2015. Modeling food web structure and selenium biomagnification in Lake
Macquarie, New South Wales, Australia, using stable carbon and nitrogen isotopes. Environ.
Toxicol. Chem. 34.3:608-17. http://onlinelibrarv.wilev.com/doi/10.1002/etc.2847/abstract
Simmons, D.B.D., and D. Wallschlager. 2005. A critical review of the biogeochemistry and
ecotoxicology of selenium in lotic and lentic environments. Environ. Toxicol. Chem.
24(6): 1331. http://onlinelibrary.wilev.eom/doi/10.1897/04-176R.l/abstract
Singh, A. and J. Nocerino. 2002. Robust estimation of mean and variance using environmental
data sets with below detection limit observations. Chemom. Intell. Lab. Syst. 60(l-2):69-86.
https ://www. sciencedirect.com/ science/article/pii/SO 169743 901001861
Stevens, D.L. and Olsen A.R. 2004. Spatially balanced sampling of natural resources. J. Am.
Stat. Assoc. 99: 262-278.
https://cfpub.epa.gov/ncer abstracts/index.cfm/fuseaction/displav.files/fileID/13339
Stewart R.A., S.N. Luoma, C.E. Schlekat, M.A. Doblin, and K.A. Hieb. 2004. Food web
pathway determines how selenium affects aquatic ecosystems: a San Francisco Bay case
study. Environ. Sci. Technol. 38: 4519-4526. https://pubs.er.usgs.gov/publication/70026685
Thornton, K. W. 1990. Perspectives on reservoir limnology. Chapter 1. In: Reservoir Limnology:
Ecological Perspectives. Thornton, K. W., B. L. Kimmel, and F. E. Payne. John Wiley and
Sons, Inc. Hoboken, NJ. 256 pp.
Tyler, C.R., and J.P. Sumpter. 1996. Oocyte growth and development in teleosts. Rev. Fish Biol.
Fisher. 6: 287-318. http://link.springer.com/article/10.1007/BF00122584
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USEPA. 1994a. Method 200.8. Determination of trace elements in waters and wastes by
inductively coupled plasma-mass spectrometry, Revision 5.4. U.S. Environmental Protection
Agency, Office of Research and Development, Environmental Monitoring Systems
Laboratory, Cincinnati, OH. https://www.epa.gov/sites/production/files/2015-
08/documents/method 200-8 rev 5-4 1994.pdf
USEPA. 1995. EPA Observational Economy Series, Volume 1: Composite Sampling. EPA-230-
R-95-005. U.S. Environmental Protection Agency, Policy, Planning and Evaluation, August
1995. https://www.epa.gov/sites/production/files/2016-03/documents/comp-samp.pdf
USEPA. 1996a. Method 3052. Microwave assisted acid digestion of siliceous and organically
based matrices, Revision 0. U.S. Environmental Protection Agency, Test Methods for
Evaluating Solid Waste, Physical/Chemical Methods (SW-846). Office of Land and
Emergency Management, Washington, DC, December 1996.
https://www.epa.gov/sites/production/files/2015-12/documents/3052.pdf
USEPA. 1996b. Method 3050B. Acid digestion of sediments, sludges, and soil, Revision 2. U.S.
Environmental Protection Agency, Test Methods for Evaluating Solid Waste,
Physical/Chemical Methods (SW-846). Office of Land and Emergency Management,
Washington, DC, December 1996. https://www.epa.gov/sites/production/files/2015-
06/documents/epa-3 05 Ob .pdf
USEPA. 2000. Guidance for assessing chemical contaminant data for use in fish advisories. Vol
1 Fish Sampling and Analysis. EPA 823-B-00-007. U.S. Environmental Protection Agency,
Office of Water, Washington, DC. https://www.epa.gov/sites/production/files/2015-
06/documents/volumel .pdf
USEPA. 2002a. Field sampling plan for the national study of chemical residues in lake fish
tissue. EPA-823-R-02-004. U.S. Environmental Protection Agency, Office of Water,
Washington, DC. http://www.epa.gov/sites/production/files/2015-07/documents/fish-studv-
fieldplan.pdf
USEPA. 2002b. Guidance on choosing a sampling design for environmental data collection.
EPA-240-R-02-005. U.S. Environmental Protection Agency, Office of Environmental
Information, Washington, DC. http://www.epa.gov/sites/production/files/2015-
06/documents/g5 s-final .pdf
USEPA. 2009. The national study of chemical residues in lake fish tissue. EPA-823-R-09-006.
U.S. Environmental Protection Agency, Office of Water, Washington, DC.
https://nepis.epa.gov/Exe/ZvPDF.cgi/P1005P2Z.PDF?Dockev=Pl 005P2Z.PDF
USEPA. 2010. Guidance for implementing the January 2001 methylmercury water quality
criterion. EPA 823-R-10-001. U.S. Environmental Protection Agency, Office of Water,
Washington, DC.
https://nepis.epa.gov/Exe/ZvPDF.cgi/P1007BKQ.PDF?Dockev=Pl 007BKQ.PDF
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USEPA. 2011. Summary of responses to the 2010 national survey of fish advisory programs.
EPA-820-R-12-001. U.S. Environmental Protection Agency, Office of Water, Washington,
DC. Accessed on-line at
https://nepis.epa.gov/Exe/ZvPDF.cgi/P100LIPR.PDF?Dockev=Pl 00LIPR.PDF
USEPA. 2013. Revised deletion process for the site-specific recalculation procedure for aquatic
life criteria. EPA 823-R-13-001. U.S. Environmental Protection Agency, Office of Water,
Washington DC. https://www.epa.gov/sites/production/files/2015-
08/documents/revised deletion process for the site-
specific recalculation procedure for aquatic life criteria.pdf
USEPA. 2014. Method 6020B (SW-846): Inductively coupled plasma - mass spectrometry,
Revision 2. U.S. Environmental Protection Agency, Test Methods for Evaluating Solid
Waste, Physical/Chemical Methods (SW-846). Office of Land and Emergency Management,
Washington, DC, July 2014. https://www.epa.gov/sites/production/files/2015-
12/documents/6020b .pdf
USEPA. 2015. National coastal condition assessment: Field operations manual. EPA-841-R-14-
007. U.S. Environmental Protection Agency, Office of Water Washington, DC.
https://www.epa.gov/sites/production/files/2016-
03/documents/national coastal condition assessment 2015 field operation manual versio
n 1.0 l.pdf
USEPA. 2018. Draft translation of selenium tissue criterion elements to site-specific water
column criterion elements for California Version 1, August 8, 2018. U.S. Environmental
Protection Agency, Office of Water, Washington, DC.
https://www.epa.gov/sites/production/files/2018-12/documents/california selenium 2040-
af79 pba 20181121 508c .pdf
USEPA. 2019a. National river and streams assessment 2018/19: Field operations manual-non-
wadeable. EPA-841-B-17-003b. U.S. Environmental Protection Agency, Office of Water,
Washington, DC. https://www.epa.gov/sites/production/files/2019-
05/documents/nrsa 1819 fom nonwadeable version 1.2.pdf
USEPA. 2019b. National rivers and streams assessment 2018/19: Field operations manual -
wadeable. EPA-841-B-17-003a. U.S. Environmental Protection Agency, Office of Water
Washington, DC. https://www.epa.gov/sites/production/files/2019-
05/documents/nrsa 1819 fom wadeable version 1.2 O.pdf
USEPA. 2021a. 2021 Revision to: Aquatic life ambient water quality criterion for selenium-
freshwater 2016. EPA 822-R-21-006. U.S. Environmental Protection Agency, Office of
Water, Office of Science and Technology, Washington, DC.
https://www.epa.gov/svstem/files/documents/2021 -08/selenium-freshwater2016-2021 -revision.pdf
USEPA. 2021b. Frequently Asked Questions (FAQs): Implementing the 2016 selenium criterion
in Clean Water Act sections 303(d) and 305(b) assessment, listing, and total maximum daily
load (TMDL) programs, Draft. EPA-832-D-21-004. U.S. Environmental Protection Agency,
Office of Water, Washington, DC. https://www.epa.gov/wqc/aquatic-life-criterion-selenium
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USEPA. 2021c. Technical support for adopting and implementing EPA's selenium 2016
criterion in water quality standards, Draft. EPA-832-D-21-001. U.S. Environmental
Protection Agency, Office of Water, Washington, DC. https://www.epa.gov/wqc/aquatic-life-
criterion-selenium
USEPA. 2021d. Frequently asked questions: Implementing water quality standards based on
EPA's 2016 recommended selenium criterion in Clean Water Act section 402 NPDES
programs, Draft. EPA-832-D-21-003. U.S. Environmental Protection Agency, Office of
Water, Washington, DC. https://www.epa.gov/wqc/aquatic-life-criterion-selenium
USGS. 2006. Determination of elements in natural-water, biota, sediment, and soil samples using
collision/reaction cell inductively coupled plasma-mass spectrometry: U.S. Geological
Survey Techniques and Methods, book 5, sec. B, chap. 1, 88 p.
https://pubs.usgs.gov/tm/2006/tm5bl/
Waddell, B. and T. May. 1995. Selenium concentrations in the razorback sucker (Xyrcnichen
texamis): substitution of non-lethal muscle plugs for muscle tissue in contaminant
assessment. Arch. Environ. Contam. Toxicol. 18: 321-326.
https://pubs.er.usgs.gov/publication/70174185
Zhou, C., J. Pagano, B.A. Crimmins, P.K. Hopke, M.S. Milligan, E.W. Murphy, and T.M.
Holsen. 2018. Polychlorinated biphenyls and organochlorine pesticides concentration
patterns and trends in top predator fish of Laurentian Great Lakes from 1999 to 2014. J.
Great Lakes Res. 44(4):716-724.
https://www.sciencedirect.com/science/article/pii/S038013301830Q42X
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Appendix A:
Egg and Ovary Sample Preparation
Scope
This guidance is for egg and ovary collection from freshwater fish. The egg extraction
method is excerpted and adapted from a more comprehensive guidance, Standard operating
procedure for evaluating selenium-induced deformities in early life stages offreshwater fish
(Janz and Muscatello 2008), that includes gamete collection, embryo incubations and
evaluation of selenium-induced deformities in freshwater fish. The ovary dissection method
was compiled from peer-reviewed literature.
1. Field collection and handling of adult fish
"Spawning adults can be collected in the field using a wide variety of
techniques, including fish traps (e.g., hoop or trap nets), electrofishing or angling
in areas close to spawning areas. Gillnets are also effective in capturing fish
during spawning migrations, but it is essential to monitor these nets constantly to
remove fish immediately after capture. If possible, the use of passive capture
methods (e.g., hoop or trap nets) is recommended since this is the least stressful
capture technique of those listed above. Trap nets are usually set up in creeks,
streams or narrows in lakes, although successful fish capture can also occur
when these nets are set perpendicular to shore in lentic habitats. Trap or hoop nets
can be purchased from fisheries suppliers, or even constructed in creeks and
streams using chicken wire, baling wire and reinforcing bar." (Janz and
Muscatello 2008)
Fish should be held in livewells until adult female fish are selected for egg collection.
2. Egg collection procedures
Fish should be carefully observed for signs of physical damage, mortality or other sources of
stress. Since any handling of the fish will remove the protective body layer of slime, fish should
be handled as little as possible using dip nets and soft material gloves. Adult fish for egg
collection should be randomly selected from livewells.
"Eggs should not be in contact with water; thus, it is imperative to dry the area
surrounding the urogenital opening with paper towels. All the material used for
egg collection should be carefully cleaned and dried. Precautions to avoid fecal,
blood or urine contamination should be taken. [Eggs] must be kept covered to
avoid direct sun exposure . [Egg collection] should proceed after recording weight
and length [of the gravid female]. Gentle pressure from behind the pectoral fins
towards the anus is applied to express the eggs. This process needs to be repeated
several times. Check that eggs are released 'clean' (e.g., without feces)
before starting collection to avoid contamination of the entire egg batch. Eggs are
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individually collected into pre-cleaned stainless steel bowls and kept covered in a
cool place until use. Collected eggs should be closely inspected and eggs with
adhered feces, urine or blood discarded by using a clean plastic pipette." (Janz
and Muscatello 2008)
Eggs are then weighed to the nearest gram using a top-loading digital scale, frozen for storage,
and shipped for laboratory analysis when appropriate. An individual or composite homogenate
tissue sample of 20 grams ww should be collected for analysis of selenium.
3. Ovary dissection procedures
Fish designated for ovary collection should be humanely euthanized, and necropsy procedures
should commence immediately following euthanasia (Wolf et al. 2004). The fish should be
placed in right lateral recumbency on a piece of aluminum foil. The left body wall should be
removed by using fine dissecting instruments (Wolf et al. 2004). To identify female specimens
for ovary collection, sex is determined by macroscopic inspection when the body cavity is
opened. The ovaries are paired organs suspended from the dorsal wall, with color ranging from
clear to white to yellow-orange. A yellow-orange color is indicative of a ripening or ripe adult
specimen. Further, increased blood flow during the reproductive season causes the ovaries to
become highly vascularized and appear reddish. In cross-section, the ovaries are round to
elliptical and contain a central cavity (lumen). In young fish, the texture of the ovaries varies
from smooth to slightly granular. The ovarian texture in a ripe fish will be highly granular
(Fisheries Information Network 2006). If inspection of the ovaries reveals that the specimen is
immature or developing, it is not recommended that the eggs/ovarian tissue be used for tissue
monitoring for selenium.
After confirmation that the specimen is a ripe female, the ovaries should be excised by severing
the oviducts and mesenteric attachments. All gonads are dissected in a caudal to cranial direction
(Wolf et al. 2004). Ovaries are then weighed to the nearest gram using a top-loading digital
scale, frozen for storage, and shipped for laboratory analysis when appropriate (Orr et al. 2012).
An individual or composite homogenate sample of 20 grams ww of tissue should be collected for
analysis of selenium.
4. Storing fish eggs and ovaries
"Eggs and ovaries should be kept frozen until analysis. After collection, samples should be kept
in a container with ice or freezer packs until transfer to a freezer (-20°C) for storage" (Janz and
Muscatello 2008). It is recommended to transfer the samples collected from each individual
female into sealed resealable plastic storage bags to "prevent water (from ice melting) entering
the sample" (Janz and Muscatello 2008). Recommendations for the storage, preservation and
holding time for egg and ovary samples are equivalent to other tissue samples. Samples should
be frozen at -20°C in plastic, borosilicate glass, quartz or PTFE bottles. The recommended
maximum holding time is six months but can be up to two years for most trace metals, including
selenium (USEPA 2000).
5. Laboratory preparation of egg and tissue samples for metal analysis
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"Egg and tissue samples should be thawed, and wet weight recorded for each
individual sample. To prevent cross contamination between samples, a plastic foil
(e.g., parafilm®) should be placed on the scale and replaced after each weighing.
Samples are oven dried at 60°C until constant weight is recorded. It is required to
record the moisture content for each individual sample in order to express
analytical data on a dry weight basis. Trace element (e.g., selenium) analysis is
routinely performed using hydride generation atomic
absorption spectrophotometry (HG-AAS) or inductively coupled plasma-mass
spectrometry (ICP-MS) and reported on a dry-weight basis." (Janz and
Muscatello 2008)
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References
Fisheries Information Network. 2006. Biological Sampling Manual. Gulf States Marine Fisheries
Commission. http://www.gsmfc.org/pubs/FIN/Biological%20Sampling%20Manual.pdf
Janz, D.M. and J.R. Muscatello. 2008. Standard operating procedure for evaluating selenium-
induced deformities in early life stages of freshwater fish. Appendix A in Selenium tissue
thresholds: Tissue selection criteria, threshold development endpoints, and potential to
predict population or community effects in the field. Washington DC, USA: North America
Metals Council - Selenium Working Group. http://www.namc.org/docs/00043675.PDF
Orr, P.L., C.I.E. Wiramanaden, M.D. Paine, W. Franklin, and C. Fraser. 2012. Food chain model
based on field data to predict westslope cutthroat trout (Oncorhynchus clarkii lewisi) ovary
selenium concentrations from water selenium concentrations in the Elk Valley, British
Columbia. Environ. Toxicol. Chem. 31(3):672-680.
http://onlinelibrarv.wilev.com/doi/10.1002/etc.173Q/abstract
USEPA. 1994a. Method 200.8: Determination of trace elements in waters and wastes by
inductively coupled plasma-mass spectrometry, Revision 5.4. U.S. Environmental Protection
Agency, Office of Research and Development, Environmental Monitoring Systems
Laboratory, Cincinnati, OH. https://www.epa.gov/sites/production/files/2015-
08/documents/method 200-8 rev 5-4 1994.pdf
USEPA. 2000. Guidance for assessing chemical contaminant data for use in fish advisories. Vol
1 Fish sampling and analysis. EPA 823-B-00-007. U.S. Environmental Protection Agency,
Office of Water, Washington, DC. https://www.epa.gov/sites/production/files/2015-
06/documents/volumel .pdf
Wolf, J.C., D.R. Dietrich, U. Friederich, J. Caunter, and A.R. Brown. 2004. Qualitative and
quantitative histomorphologic assessment of fathead minnow Pimephalespromelas gonads
as an endpoint for evaluating endocrine-active compounds: a pilot methodology study.
Toxicol. Pathol. 32(5): 600-612. http://tpx.sagepub.com/content/32/5/600.full.pdf+html
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Appendix B:
Spawning Seasons for Example Fish Assemblages from Select U.S.
Watersheds
This appendix contains spawning season calendars for fish assemblages from selected
watersheds in six different areas of the United States. The calendars are intended to provide
examples of spawning periods for fish species commonly collected in those areas. EPA
recommends that monitoring agencies use all available locally relevant resources to
determine the appropriate time to collect fish for the purpose of implementing the selenium
criterion, including contacting their local natural resources or fish and game agency.
References
Auer, N.A. (ed). 1982. Identification of larval fishes of the Great Lakes basin with emphasis on
the Lake Michigan drainage. Great Lakes Fishery Commission, Ann Arbor, MI. Special Pub.
82-3:744 pp.
Boschung, H.T. and R.L. Mayden. 2004. Fishes of Alabama. Washington, D.C: Smithsonian
Books.
Nevada Division of Environmental Protection. 2006. Fact Sheet. Temperature Criteria for
Various Fish Species as Recommended to NDEP during the 1980s.
https://ndep.nv.gov/uploads/documents/recommended temp criteria06 1 .pdf
Page, L.M. and B.M. Burr. 1991. Peterson Field Guides: Freshwater Fishes. Boston: Houghton
Mifflin Company.
Scarola, J.F. 1973. Freshwater Fishes of New Hampshire. New Hampshire Fish and Game
Department, Division of Inland and Marine Fisheries.
Wang, J.C.S. and R.J. Kernehan. 1979. Fishes of the Delaware Estuaries: A Guide to the Early
Life Histories. Towson, MD: EA Communications.
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Spawning Seasons for Example Fish Assemblages in the Merrimack River, MA and NH Watershed
Family
Scientific Name
Common Name
Spawning Season
Atherinopsidae
Menidict menidia
Atlantic Silverside
April through August
Catostomidae
Catostomus commersonii
White Sucker
March through July
Centrarchidae
Ambloplites rupestris
Rock Bass
April through July
Centrarchidae
Enneacanthns obesus
Banded Sunfish
April through July
Centrarchidae
Lepomis aiiritus
Redbreast Sunfish
April through July
Centrarchidae
Lepomis gibbosus
Pumpkinseed
June through August
Centrarchidae
Lepomis macrochirns
Bluegill
May through August
Centrarchidae
Micropterns dolomieu
Smallmouth Bass
April through June
Centrarchidae
Micropterns salmoides
Largemouth Bass
April through June
Centrarchidae
Pomoxis nigromaculatus
Black Crappie
April through July
Clupeidae
Dorosomct cepedicmum
Gizzard Shad
March through August
Cyprinidae
Cctrctssius auratus
Goldfish
March through August
Cyprinidae
Cyprinus cctrpio
Common Carp
April through August
Cyprinidae
Luxilus cornutiis
Common Shiner
May through July
Cyprinidae
Notemigonus crysoleuccts
Golden Shiner
May through July
Cyprinidae
Notropis atherinoides
Emerald Shiner
May through June
Cyprinidae
Notropis bifrenatus
Bridle Shiner
May through August
Cyprinidae
Notropis hiidsonins
Spottail Shiner
May through September
Cyprinidae
Rhinichthvs atratulus
Blacknose Dace
April through July
Cyprinidae
Rhinichthvs cataractae
Longnose Dace
April through June
Cyprinidae
Semotilus atromaculatus
Creek Chub
March through June
Cyprinidae
Semotilus corporalis
Fallfish
April through May
Esocidae
Esox hiciiis
Northern Pike
March through May
Esocidae
Esox niger
Chain Pickerel
March through May
Fundulidae
Fundulus diaphctmis
Banded Killifish
April through August
Fundulidae
Fundulus heteroclitus
Mummichog
June through July
Gadidae
Lota lota
Burbot
January through April
Gasterosteidae
Apeltes quadroons
Fourspine Stickleback
April through May
Gasterosteidae
Gasterostens aculeatus
Threespine Stickleback
March through June
Gasterosteidae
Pungitius pungitius
Nine spine Stickleback
April through August
Ictaluridae
Ameiimis catus
White Catfish
May through July
Ictaluridae
Ameiimis natalis
Yellow Bullhead
May through June
Ictaluridae
Ameiimis nebulosus
Brown Bullhead
April through June
Ictaluridae
Ictalurus punctatus
Channel Catfish
April through September
Ictaluridae
Notiims gyrinns
Tadpole Madtom
May through July
Ictaluridae
Notiims insignis
Margined Madtom
June through July
Moronidae
Morone americana
White Perch
May through June
Percidae
Etheostoma fiisiforme
Swamp Darter
April through May
Percidae
Etheostoma olmstedi
Tessellated Darter
March through May
Percidae
Perca flavescens
Yellow Perch
May through July
Percidae
Sander vitreus
Walleye
April through May
Salmonidae
Oncorhvnchiis mykiss
Rainbow Trout
April through June
Salmonidae
Salmo trutta
Brown Trout
October through February
Salmonidae
Salvelinus fontinalis
Brook Trout
September through November
(Scarola 1973, Page and Burr 1991)
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Spawning Seasons for Example Fish Assemblages in the Delaware River, DE Watershed
Family
Scientific Name
Common Name
Spawning Season
Aphredoderidae
Aphredoderus sayanus
Pirate Perch
April through May
Atherinopsidae
Membrcts mcirtinicci
Rough Silverside
May through August
Atherinopsidae
Menidict peninsulae
Tidewater Silverside
May through August
Atherinopsidae
Menidia menidict
Atlantic Silverside
April through August
Catostomidae
Catostomus commersonii
White Sucker
March through May
Catostomidae
Erimyzon oblongiis
Creek Chubsucker
March through May
Centrarchidae
Acantharchus pomotis
Mud Sunfish
May through June
Centrarchidae
Enneacanthus chaetodon
Blackbanded Sunfish
May through July
Centrarchidae
Enneacanthus gloriosus
Bluespotted Sunfish
May through September
Centrarchidae
Enneacanthus obesus
Banded Sunfish
June through September
Centrarchidae
Lepomis auritus
Redbreast Sunfish
May through June
Centrarchidae
Lepomis gibbosus
Pumpkinseed
May through August
Centrarchidae
Lepomis macrochirus
Bluegill
May through August
Centrarchidae
Micropterus salmoides
Largemouth Bass
April through June
Centrarchidae
Pomoxis annularis
White Crappie
April through June
Centrarchidae
Pomoxis nigromaculatus
Black Crappie
May through June
Clupeidae
Dorosoma cepedianum
Gizzard Shad
April through June
Cyprinidae
Carassius auratus
Goldfish
June through July
Cyprinidae
Cyprinus carpio
Common Carp
May through July
Cyprinidae
Hybognathus nuchalis
Mississippi Silvery Minnow
April through May
Cyprinidae
Notemigonus crysoleucas
Golden Shiner
April through July
Cyprinidae
Cyprinella analostana
Satinfin Shiner
March through July
Cyprinidae
Notropis bifrenatus
Bridle Shiner
March through August
Cyprinidae
Notropis chalybaeus
Ironcolor Shiner
April through May
Cyprinidae
Notropis hudsonius
Spottail Shiner
April through July
Cyprinidae
Rhinichthys atratiilus
Blacknose Dace
May through June
Esocidae
Esox americanus americanus
Redfin Pickerel
February through March
Fundulidae
Fundulus diaphanus
Banded Killifish
April through August
Fundulidae
Fundulus heteroclitus
Mummichog
April through September
Fundulidae
Fundulus majalis
Striped Killifish
April through September
Fundulidae
Lucania parva
Rainwater Killifish
May through July
Ictaluridae
Ameiurus catus
White Catfish
April through July
Ictaluridae
Ameiurus nebulosus
Brown Bullhead
May through July
Ictaluridae
Ictalurus punctatus
Channel Catfish
May through July
Ictaluridae
Noturus gyrinus
Tadpole Madtom
May through July
Moronidae
Morone americana
White Perch
April through June
Percidae
Etheostoma fusiforme
Swamp Darter
April through May
Percidae
Etheostoma olmstedi
Tessellated Darter
March through May
Percidae
Perca flavescens
Yellow Perch
March through April
Poeciliidae
Gambusia afflnis
Mosquitofish
May through August
Umbridae
Umbra pygmaea
Eastern Mudminnow
April through June
(Wang and Kernehan 1979, Page and Burr 1991)
54
-------
Spawning Seasons for Example Fish Assemblages in the Cahaba River, AL Watershed
Family
Scientific Name
Common Name
Spawning Season
Amiidae
Amia calva
Bowfin
March through June
Atherinopsidae
Labidesthes sicculus
Brook Silverside
June through August
Catostomidae
Carpiodes cyprinus
Quillback
March through September
Catostomidae
Carpiodes velifer
Highfin Carpsucker
May through July
Catostomidae
Erimyzon oblongiis
Creek Chubsucker
March through May
Catostomidae
Erimyzon sucetta
Lake Chubsucker
March through April
Catostomidae
Erimyzon tenuis
Sharpfin Chubsucker
March through April
Catostomidae
Hypentelium etowanum
Alabama Hog Sucker
April through June
Catostomidae
Ictiobus bubalus
Smallmouth Buffalo
March through April
Catostomidae
Minvtrema melanops
Spotted Sucker
April through May
Catostomidae
Moxostoma carinatum
River Redhorse
April
Catostomidae
Moxostoma duquesnii
Black Redhorse
April through May
Catostomidae
Moxostoma erythruriim
Golden Redhorse
April through June
Catostomidae
Moxostoma poeciluriim
Blacktail Redhorse
April
Centrarchidae
Ambloplites ariommus
Shadow Bass
May through October
Centrarchidae
Centrarchns macropterns
Flier
February through May
Centrarchidae
Lepomis macrochirns
Bluegill
March through May
Centrarchidae
Lepomis marginatus
Dollar Sunfish
May through August
Centrarchidae
Lepomis megalotis
Longear Sunfish
May through August
March through May;
Centrarchidae
Lepomis microlophus
Redear Sunfish
September through November
Centrarchidae
Lepomis miniatus
Redspotted Sunfish
March through September
Centrarchidae
Micropterus coosae
Redeye Bass
May through July
Centrarchidae
Micropterus dolomieu
Smallmouth Bass
March through May
Centrarchidae
Micropterus punctulatus
Spotted Bass
April through May
Centrarchidae
Micropterus salmoides
Largemouth Bass
April through June
Centrarchidae
Pomoxis annularis
White Crappie
April through June
Centrarchidae
Pomoxis nigromaciilatiis
Black Crappie
February through May
Clupeidae
Dorosoma cepedianum
Gizzard Shad
April through May
Clupeidae
Dorosoma petenense
Threadfin Shad
April through August
Cottidae
Cottus carolinae
Banded Sculpin
January through March
Cyprinidae
Campostoma oligolepis
Largescale Stoneroller
April through May
Cyprinidae
Cyprinella callistia
Alabama Shiner
March through May
Cyprinidae
Cyprinella trichroistia
Tricolor Shiner
June through July
Cyprinidae
Cyprinella vennsta
Blacktail Shiner
March through October
Cyprinidae
Hybognathus nucha lis
Mississippi Silvery Minnow
March through April
Cyprinidae
Hvbopsis winchelli
Clear Chub
February through April
Cyprinidae
Luxilus chrysocephaliis
Striped Shiner
April through August
Cyprinidae
Lythruriis bellus
Pretty Shiner
April through June
Cyprinidae
Macrhybopsis storeriana
Silver Chub
May through August
Cyprinidae
Notemigonus crysoleucas
Golden Shiner
April through July
Cyprinidae
Notropis ammophilus
Orangefin Shiner
April through October
Cyprinidae
Notropis asperifrons
Burrhead Shiner
April through June
Cyprinidae
Notropis atherinoides
Emerald Shiner
May through July
Cyprinidae
Notropis bailevi
Rough Shiner
May through October
Cyprinidae
Notropis buccatus
Silveijaw Minnow
March through June
Cyprinidae
Notropis candidus
Silverside Shiner
June through September
Cyprinidae
Notropis chrosomus
Rainbow Shiner
May through June
55
-------
Family
Scientific Name
Common Name
Spawning Season
Cyprinidae
Notropis edwardrcmeyi
Cyprinidae
Notropis stilbius
Cyprinidae
Notropis texanus
Cyprinidae
Notropis uranoscopus
Cyprinidae
Notropis volucellus
Cyprinidae
Opsopoeodus emiliae
Cyprinidae
Phenctcobius catostomus
Cyprinidae
Pimephcdes notatus
Cyprinidae
Pimephcdes vigilax
Cyprinidae
Semotilus atromaculatus
Cyprinidae
Semotilus thoreauianus
Elassomatidae
Elctssoma zonatum
Esocidae
Esox americanus
Esocidae
Esox niger
Fundulidae
Fundulus olivaceiis
Hiodontidae
Hiodon tergisus
Ictaluridae
Ameiimis melcts
Ictaluridae
Ameiimis natcdis
Ictaluridae
Ameiimis nebulosus
Ictaluridae
Ictalurus furcatus
Ictaluridae
Ictalurus punctatus
Ictaluridae
Notimis funebris
Ictaluridae
Notimis gyrinns
Ictaluridae
Pylodictis olivaris
Lepisosteidae
Lepisostens oculatus
Lepisosteidae
Lepisostens ossens
Moronidae
Morone chrysops
Percidae
Ammocrvpta beanii
Percidae
Etheostoma meridicmum
Percidae
Etheostoma chlorosomum
Percidae
Etheostoma jordcmi
Percidae
Etheostoma nigrum
Percidae
Etheostoma parvipinne
Percidae
Etheostoma ramsevi
Percidae
Etheostoma rupestre
Percidae
Etheostoma stigmaeum
Percidae
Etheostoma swaini
Percidae
Percina kathae
Percidae
Percina maculata
Percidae
Percina nigrofasciata
Percidae
Percina vigil-
Percidae
Sander vitreus
Sciaenidae
Aplodinotiis grunniens
(Boschung and Mayden 2004)
Fluvial Shiner
Silverstripe Shiner
Weed Shiner
Skygazer Shiner
Mimic Shiner
Pugnose Minnow
Riffle Minnow
Bluntnose Minnow
Bullhead Minnow
Creek Chub
Dixie Chub
Banded Pygmy Sunfish
Redfin Pickerel
Chain Pickerel
Blackspotted Topminnow
Mooneye
Black Bullhead
Yellow Bullhead
Brown Bullhead
Blue Catfish
Channel Catfish
Black Madtom
Tadpole Madtom
Flathead Catfish
Spotted Gar
Longnose Gar
White Bass
Naked Sand Darter
Southern Sand Darter
Bluntnose Darter
Greenbreast Darter
Johnny Darter
Goldstripe Darter
Alabama Darter
Rock Darter
Speckled Darter
Gulf Darter
Mobile Logperch
Blackside Darter
Blackbanded Darter
Saddleback Darter
Walleye
Freshwater Drum
May through June
March through August
February through October
May through July
April through August
April through September
April through May
April through August
May through August
April through May
April through May
March through April
April through May
April through October
March through September
April through May
May through August
April through June
April through August
April through June
April through July
May through June
May through September
June through July
May through July
April through August
February through March
March through October
April through June
April
April through May
March through May
March through April
March through May
March through April
March through May
March through April
April through June
March through June
May through June
February through April
March through April
May through June
56
-------
Spawning Seasons for Example Fish Assemblages in the Chicago River, IL Watershed
Family
Scientific Name
Common Name
Spawning Season
Amiidae
Amia calva
Bowfin
March through June
Catostomidae
Catostomus commersonii
White Sucker
April through May
Centrarchidae
Ambloplites mpestris
Rock Bass
May through July
Centrarchidae
Lepomis cycmellus
Green Sunfish
June through August
Centrarchidae
Lepomis humilis
Orangespotted Sunfish
May through July
Centrarchidae
Lepomis gibbosus
Pumpkinseed
May through July
Centrarchidae
Lepomis gulosus
Warmouth
May through August
Centrarchidae
Lepomis macrochirns
Bluegill
May through August
Centrarchidae
Micropterns dolomieu
Smallmouth Bass
April through June
Centrarchidae
Micropterns sctlmoides
Largemouth Bass
April through June
Centrarchidae
Pomoxis nigromaculatus
Black Crappie
May through July
Clupeidae
Dorosomct cepedianum
Gizzard Shad
May through July
Cyprinidae
Campostoma anomalum
Central Stoneroller
April through July
Cyprinidae
Carassins auratus
Goldfish
May through June
Cyprinidae
Cyprinella spiloptera
Spotfin Shiner
May through August
Cyprinidae
Cyprimis cctrpio
Common Carp
May through August
Cyprinidae
Hvbopsis dorsalis
Bigmouth Shiner
May through June
Cyprinidae
Notemigonus crysoleuccts
Golden Shiner
May through August
Cyprinidae
Notropis atherinoides
Emerald Shiner
April through August
Cyprinidae
Notropis hiidsonins
Spottail Shiner
June through July
Cyprinidae
Notropis straminens
Sand Shiner
May through July
Cyprinidae
Pimephcdes notatus
Bluntnose Minnow
May through August
Cyprinidae
Pimephcdes promelas
Fathead Minnow
May through August
Cyprinidae
Semotilus cttromaculatus
Creek Chub
April through June
Cyprinodontidae
Fundulus notatus
Blackstripe Topminnow
May through August
Esocidae
Esox americanus
Grass Pickerel
May through June; November
Esocidae
Esox hiciiis
Northern Pike
March through May
Gobiidae
Neogobins melanostomus
Round Goby
April through May
Ictaluridae
Ameiimis melcts
Black Bullhead
May through June
Ictaluridae
Ameiurus natalis
Yellow Bullhead
May through June
Ictaluridae
Ictcdurus punctatus
Channel Catfish
April through August
Moronidae
Morone americana
White Perch
May through June
Moronidae
Morone chrysops
White Bass
April through June
Moronidae
Morone mississippiensis
Yellow Bass
April through May
Percidae
Etheostoma nigrum
Johnny Darter
April through June
Percidae
Sander vitrens
Walleye
April through May
Percidae
Percaflavescens
Yellow Perch
May through July
Umbridae
Umbra limi
Central Mudminnow
April through May
(Auer 1982, Page and Burr 1991)
57
-------
Spawning Seasons for Example Fish Assemblages in the Truckee and Carson River, NV
Watersheds
Family
Scientific Name
Common Name
Spawning Season
Centrarchidae
Micropterns dolomieu
Smallmouth Bass
April through July
Centrarchidae
Micropterns salmoides
Largemouth Bass
April through July
Centrarchidae
Lepomis macrochirns
Bluegill
May through August
Centrarchidae
Pomoxis nigromaculatus
Black Crappie
May through July
Ictaluridae
Ictaluridae
Catfish species
June through July
Moronidae
Morone saxatilis
Striped Bass*
April through June
Moronidae
Morone chrysops
White Bass
April through June
Percidae
Sander vitreus
Walleye
January through April
Salmonidae
Oncorhvnchiis mykiss
Rainbow Trout
March through May
Salmonidae
Salmo trutta
Brown Trout
January through March
Salmonidae
Pros opium williamsoni
Mountain Whitefish
October through December
* This population of striped bass is landlocked and cannot migrate out to sea.
(Nevada Division of Environmental Protection 2006)
58
-------
Spawning Seasons for Example Fish Assemblages in the Rio Grande and Colorado River, TX
Watersheds
Family
Scientific Name
Common Name
Spawning Season
Amiidae
Amia calva
Bowfin
March through June
Anguillidae
Anguillct rostrata
American Eel
February through June
Catostomidae
Ictiobus bubalus
Smallmouth Buffalo
March through September
Catostomidae
Ictiobus cyprinellus
Bigmouth Buffalo
April through May
Catostomidae
Ictiobus niger
Black Buffalo
April through May
Centrarchidae
Lepomis macrochirus
Bluegill
April through September
Centrarchidae
Lepomis cyanellus
Green Sunfish
April through August
Centrarchidae
Lepomis megalotis
Longear Sunfish
May through June
Centrarchidae
Lepomis auritus
Redbreast Sunfish
April through October
Centrarchidae
Lepomis microlophus
Redear Sunfish
May through July
Centrarchidae
Lepomis gulosus
Warmouth
March through October
Centrarchidae
Micropterns sctlmoides
Largemouth Bass
February through May
Centrarchidae
Micropterns dolomieu
Smallmouth Bass
April through May
Centrarchidae
Micropterns punctulatus
Spotted Bass
April through June
Centrarchidae
Micropterns treculii
Guadalupe Bass
March through June
Centrarchidae
Pomoxis nigromaculatus
Black Crappie
March through May
Centrarchidae
Pomoxis annularis
White Crappie
March through May
Cichlidae
Herichthys cyanoguttatus
Rio Grande Cichlid
March through August
Clupeidae
Dorosoma cepedianum
Gizzard Shad
April through June
Clupeidae
Dorosoma petenense
Threadfin Shad
April through September
Cyprinidae
Ctenopharyngodon idella
Grass Carp
April through July
Cyprinidae
Cyprimis carpio
Common Carp
March through June
Cyprinidae
Cyprinella lutrensis
Red Shiner
April through September
Cyprinidae
Cyprinella venusta
Blacktail Shiner
April through September
Cyprinidae
Notropis amabilis
Texas Shiner
February through September
Cyprinidae
Notemigonus crysoleucas
Golden Shiner
April through July
Cyprinidae
Pimephales promelas
Fathead Minnow
May through September
Esocidae
Esox niger
Chain Pickerel
December through February
Ictaluridae
Ictalurus furcatus
Blue Catfish
April through May
Ictaluridae
Ictaliirus punctatus
Channel Catfish
April through June
Ictaluridae
Pylodictis olivaris
Flathead Catfish
June through July
Ictaluridae
Ameiurus melas
Black Bullhead
April through June
Ictaluridae
Ameiurus natalis
Yellow Bullhead
May through July
Lepisosteidae
Atractosteus spatula
Alligator Gar
April through May
Lepisosteidae
Lepisosteus ocidatus
Spotted Gar
April through June
Lepisosteidae
Lepisosteus osseus
Longnose Gar
April through July
Lepisosteidae
Lepisosteus platostomus
Shortnose Gar
May through July
Moronidae
Morone chrysops
White Bass
March through May
Moronidae
Morone mississippiensis
Yellow Bass
April through June
Moronidae
Morone saxatilis
Striped Bass*
February through April
Percidae
Sander vitreus
Walleye
February through April
Polyodontidae
Polvodon spathida
Paddlefish
59
February through June
-------
Family Scientific Name Common Name Spawning Season
Salmonidae Oncorhvnchiis mykiss Rainbow Trout November through February
Sciaenidae Aplodinotiis grunniens Freshwater Drum April through June
Sciaenidae Sciaenops ocellatiis Red Drum August through October
* This population of striped bass is landlocked and cannot migrate out to sea.
(Hendrickson and Cohen 2015, Texas Parks and Wildlife Department 2016)
60
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Appendix C:
Conversion of Wet to Dry Tissue Weight
Conversion of Wet to Dry Tissue Weight
Selenium data in fish tissues can be reported in either dry weight or wet weight concentrations. It
is essential that exposure assessors be aware of this difference so that they may ensure
consistency between units when comparing data. If the contaminant concentration is measured in
wet weight of fish, then the concentration must be converted to dry weight units in order to be
compared to the selenium criterion, which is expressed in dry weight (USEPA 2021). Wet
weight may be converted to dry weight, and vice versa, using the following equations:
WW = DW x [1 - (percent moisture/100)] (USEPA 2011)
DW = WW / [1 - (percent moisture/100)] (USEPA 2011)
Measurements reported as wet weight can be converted to equivalent dry weights using available
percent moisture data for the relevant species and tissue type. If percent moisture data is
unavailable for a fish species, percent moisture data for a similar species (i.e., same genus or, if
unavailable, same family) may be used. Table C-l lists percent moisture of some species by
tissue type (USEPA 2021). Percent moisture can vary within species; therefore, the data in Table
C-l should generally be used when dealing with historical data. When using field collected data,
measuring % moisture within the field collected sample will provide the most accurate
measurement of % moisture, thus giving more accurate conversions between dry weight and wet
weight data.
Table C-l. Percent moisture by species and tissue type
Average
% Moisture by Tissue
%
Whole
Egg-
Scientific Name
Common Name
Moisture
-body
Muscle
ovary
Reference
Cyprinus carpio
Common Carp
75.64a
75.8 lb
aUSEPA 2014;
bChatakondi et al.
1995
Rhinichthys cataractae
Longnose Dace
73.25
USEPA 2014
Rhinichthys atratulus
Blacknose Dace
73.75
USEPA 2014
Semotilus
Creek Chub
76.71
USEPA 2014
atromaculatus
Pimephales promelas
Fathead Minnow
76.64a
75.3b
USEPA 2014;
bUSEPA 2015
Pimephales notatus
Bluntnose Minnow
74.8
USEPA 2014
Nocomis micropogon
River Chub
75.2
USEPA 2014
Ictalurus punctatus
Channel Catfish
81.223
78.43b
aPinkney 2003;
bMay et al. 2009
61
-------
Average
% Moisture by Tissue
%
Whole
Egg-
Scientific Name
Common Name
Moisture
-body
Muscle
ovary
Reference
Ictcdurus melcts
Black Bullhead
76.82
USEPA 2014
Pvlodictis olivaris
Flathead Catfish
75.97
May et al. 2009
Catostomus
White Sucker
77.37
USEPA 2014
commersonii
Coregonus
clupeaformis
Lake Whitefish
80
Rieberger 1992
Oncorhvnchus kisntch
Coho Salmon
80
Rieberger 1992
Oncorhvnchus mvkiss
Rainbow Trout
77.54
61.2
USEPA 2021
Sander canadensis
Sauger
77
USEPA 2014
Perca flavescens
Yellow Perch
73.98
USEPA 2014
Micropterns salmoides
Largemouth Bass
75.74a
79.06b
78.53c
aUSEPA 2014;
bPinkney 2003,
cMay et al. 2009
Micropterns dolomieii
Smallmouth Bass
74.22
USEPA 2014
Pomoxis annularis
White Crappie
80.57
May et al. 2009
Pomoxis
Black Crappie
79.75
May et al. 2009
nigromaculatus
Lepomis macrochirns
Bluegill
74.8
80.09
76
USEPA 2021
Ambloplites rupestris
Rock Bass
74.95
USEPA 2014
Esox hiciiis
Northern Pike
78
Rieberger 1992
Pvlodictis olivaris
Flathead Catfish
58.97
May et al. 2009
Scaphirhvnehus
platonmchas
Shovelnose
Sturgeon
77.13
47.18
May et al. 2009
References
Chatakondi, N., R.T. Lovell, P.L. Duncan, M. Hayat, T.T. Chen, D.A. Powers, J.D. Weete, K.
Cummins, and R.A. Dunham. 1995. Body composition of transgenic common carp, Cyprimts
carpio, containing rainbow growth hormone gene. Aquaculture 138: 99-109.
http://www.sciencedirect.com/science/article/pii/004484869501Q785
May, T.W., M.J. Walther, W.G. Brumbaugh, and M. McKee, 2009. Concentrations of elements
in whole-body fish, fish contaminant monitoring program: U.S. Geological Survey Open-File
Report 2009-1278, 11 p. https://pubs.usgs.gov/of/2009/1278/pdf/QF2009 1278.pdf
Pinkney, A.E. 2003. Investigation of fish tissue contaminant concentrations at Painted Turtle
Pond, Occoquan Bay National Wildlife Refuge, Woodbridge, Virginia. Annapolis, MD: US
Fish and Wildlife Service.
Rieberger, K. 1992. Metal concentrations in fish tissue from uncontaminated B.C Lakes.
Ministry of Environment, Lands and Parks, Province of British Columbia.
62
-------
www2.gov.bc.ca/assets/gov/environment/air-land-water/water/waterqualitv/monitoring-
water-qualitv/wq be metal in fish.pdf
USEPA. 2011. Exposure factors handbook: 2011 Edition. National Center for Environmental
Assessment, Washington, DC; EPA/600/R-09/052F. Available from the National Technical
Information Service, Springfield, VA, and online at https://www.epa.gov/expobox/about-
exposure-factors-handbook
USEPA. 2014. External peer review draft aquatic life ambient water quality criterion for
selenium-freshwater 2014. EPA 822-P-14-001. U.S. Environmental Protection Agency,
Office of Water, Office of Science and Technology, Washington, DC.
https://19ianuarv2017snapshot.epa.gov/sites/production/files/2016-
07/documents/2014 draft document external peer review draft aquatic life ambient wqc
for se freshwater.pdf
USEPA. 2021. 2021 Revision to: Aquatic life ambient water quality criterion for selenium-
freshwater 2016. EPA 822-R-21-006. U.S. Environmental Protection Agency, Office of
Water, Office of Science and Technology, Washington, DC.
https://www.epa.gov/svstem/files/documents/2021 -08/selenium-freshwater2016-2021 -revision.pdf
63
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Appendix D: Extended List of Potential Target Species for Monitoring
of Selenium in Fish Tissue
This appendix is intended for use with the recommendations in section 2.3 and Table 3. This
appendix provides detailed information for the target species identified in Table 3, as well as
additional species that may be considered appropriate for monitoring in certain situations (e.g.,
when species in Table 3 are unavailable for collection).
The tables in this appendix are generally organized by taxon (with the exception of a group of
molluscivores) and includes nomenclature, distribution within US states, basic habitat
information (warmwater [WW] or cool or coldwater [CW]), presence in waterbodies (e.g., lotic,
lentic), adult diet, and adult trophic level. Information is presented by the following groupings:
1. Sturgeon in the family Acipenseridae
2. Sunfish and other genera in the family Centrarchidae
3. Trout and other genera in the family Salmonidae
4. Freshwater molluscivores & related genera (Catostomidae)
5. Minnows in the family Cyprinidae
6. Darters in the family Percidae
7. Sculpin in the family Scorpionidae
Information sources for these species include NatureServe
(https://explorer.natureserve.org/Search). and the USGS NAS - Nonindigenous Aquatic Species
Database (https://nas.er.usgs.gov/). Users of this Appendix should consult with both as they
examine available information to make decisions about target species in state and tribal waters as
they develop sampling plans.
64
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1. Sturgeon
The family Acipenseridae is comprised of twenty-seven species in four genera, with two genera
(Acipenser and Scaphyrhynchus) occurring in the US. Sturgeon in the genus Acipenser (e.g., white
sturgeon) include three freshwater species. Sturgeons are long-lived, late maturing bottom feeding fishes
inhabiting large river systems and estuaries. Independent monitoring for these species is generally
discouraged since most populations are under pressure from habitat loss and other stressors and
coordination with federal agencies (US Fish and Wildlife Service or NOAA's National Marine Fishery
Service) is therefore recommended prior to developing sampling plans that may include these species.
Table D-l. Species in the family Acipenseridae that may be sampled for implementation of the
selenium criterion.
Name
(Common,
Scientific)
Distribution
Habitat
(WW/CW)
Lentic/Lotic
Adult Diet/
Trophic Level
Genus Acipenser
White Sturgeon
(Acipenser
transmontanus)
US: AK, AZ, CA, ID, MT, OR, WA
WW
Lotic
Estuarine
Invertivore
Piscivore
Molluscivore
TL3/TL4
Map: https://nas.er.usas.aov/aueries/FactSheet.aspx?SpeciesID=300
79/Acipenser transmontanus
Info:
https://explorer.natureserve.ora/Taxon/ELEMENT GL0BAL.2.1006'
Shortnose Sturgeon*
(Acipenser
brevi rostrum)
US: CT, DC, DE, FL, GA, MA, MD, ME,
NC, NH, NJ, NY, PA, RI, SC, VA
WW
Lotic
Estuarine
Invertivore
Molluscivore
TL3
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2.105033/Acipenser brevirostrum
Lake Sturgeon*
{Acipenser
fhivescens)
US: AL, AR, GA, IA, IL, IN, KS, KY, MI,
MN, MO, NC, ND, NE, NY, OH, PA, SD,
TN, VT, WI, WV
WW
Lentic
Lotic
Invertivore
Molluscivore
TL3
Map: https://nas.er,usas.aov/aueries/FactSheet.aspx?SpeciesID=299
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2.104232/Acipenser fulvescens
Other Sturgeon:
65
-------
Name
(Common,
Scientific)
Distribution
Habitat
(WW/CW)
Lentic/Lotic
Adult Diet/
Trophic Level
Shovelnose Sturgeon
(Scaphirhynchns
platorynchus)
US: AL, AR, IA, IL, IN, KS, KY, LA, MN,
MO, MS, MT, ND, NE, NM, OH, OK, PA,
SD, TN, TX, WI, WV, WY
WW
Lotic
Estuarine
Invertivore
TL3
Map & Info:
https://explorer.natureserve.ora/Taxon/ELEMENT GL0BAL.2.103361/Scaphirhvnchus platorvnchus
* Species documented to consume invasive zebra mussels and quagga mussels in the genus Dreissena by the Army
Corps of Engineers (Kirk, 2001).
66
-------
2. Sunfish (genus Lepomis), and other genera in the family Centrarchidae
The bluegill is a species of freshwater fish and a member of the sunfish family Centrarchidae of the order
Perciformes. It is native to North America and lives in streams, rivers, lakes, and ponds. The centrarchid
family comprises 38 species of fish and includes many recreational and sportfish familiar to North
Americans, including the rock bass, largemouth bass, pumpkinseed, and crappies. This family typically
inhabits medium to large warmwater river systems and all sizes of lentic waterbodies. All species in the
family are native to only North America.
Table D-2. Species in the family Centrarchidae that may be sampled for implementation of the
selenium criterion.
Name
(Common,
Scientific)
Distribution
Habitat
(WW/CW)
Lentic/Lotic
Adult Diet/
Trophic
Level
Genus Lepomis
Bluegill
(Lepomis
macrochiriis)
US: AL, AR, AZ, CA, CO, CT, DC, DE,
FL, GA, IA, ID, IL, IN, KS, KY, LA, MA,
MD, MI, MN, MO, MS, MT, NC, ND, NE,
NH, NJ, NM, NN, NV, NY, OH, OK, OR,
PA, RI, SC, SD, TN, TX, UT, VA, VT,
WA, WI, WV, WY
WW
Lentic
Lotic
Invertivore
Piscivore
TL3
Map: https://nas.er.usas.aov/aueries/FactSheet.aspx?SpeciesID=385
.101764/Lepomis macrochirus
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GL0BAL.2
Pumpkinseed*
(Lepomis gibbosus)
US: AL, AZ, CA, CO, CT, DC, DE, GA,
IA, ID, IL, IN, KY, MA, MD, ME, MI,
MN, MT, NC, ND, NE, NH, NJ, NV, NY,
OH, OR, PA, RI, SC, TN, TX, VA, VT,
WA, WI, WV, WY
WW
Lentic
Lotic
Invertivore
Molluscivore
TL3
Map: https://nas.er .usas.aov/aueries/FactSheet.aspx?SpeciesID=382
!.105048/Lepomis aibbosus
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.^
Redear Sunfish*
(Lepomis
microlophus)
US: AL, AR, AZ, DC, DE, FL, GA, IA, IL,
IN, KS, KY, LA, MI, MO, MS, NC, NE,
NM, NV, OH, OK, OR, PA, SC, TN, TX,
VA, VT, WV
WW
Lentic
Lotic
Invertivore
Molluscivore
TL3
Map: https://nas.er.usas.aov/aueries/FactSheet.aspx?SpeciesID=390
Info:
https://explorer.natureserve.ora/Taxon/ELEMENT GL0BAL.2.100707/Lepomis microlophus
67
-------
Name
(Common,
Scientific)
Distribution
Habitat
(WW/CW)
Lentic/Lotic
Adult Diet/
Trophic
Level
Green sunfish
(Lepomis cyanellus)
US: AL, AR, AZ, CA, CO, CT, DC, DE,
FL, GA, IA, ID, IL, IN, KS, KY, LA, MA,
MD, ME, MI, MN, MO, MS, MT, NC, ND,
NE, NJ, NM, NN, NV, NY, OH, OK, OR,
PA, SC, SD, TN, TX, UT, VA, WA, WI,
WV, WY
WW
Lentic
Lotic
Piscivore
Invertivore
TL3/4
Mao: https://nas.er .usas.aov/aueries/FactSheet.aspx?SpeciesID=380
.103917/Lepomis cvanellus
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2
https://pubs.usas.aov/pp/1803/pdf/ppl803.pdf
Redbreast Sunfish*
(Lepomis auritus)
US: AL, AR, CT, DC, DE, FL, GA, KY,
LA, MA, MD, ME, MS, NC, NH, NJ, NY,
OK, PA, RI, SC, TN, TX, VA, VT, WV
WW
Lentic
Lotic
Invertivore
TL3
Map: https://nas.er.usas.aov/aueries/FactSheet.aspx?SpeciesID=379
.101339/Lepomis auritus
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2
Longear Sunfish
(Lepomis megalotis)
US: AL, AR, FL, GA, IA, IL, IN, KS, KY,
LA, MD, MN, MO, MS, NC, NJ, NM, OH,
OK, PA, TN, TX, VA, WI, WV
WW
Lentic
Lotic
Piscivore
Invertivore
TL3/4
Map: https://nas.er .usas.aov/queries/FactSheet.aspx?SpeciesID=388
.885331/Lepomis meaalotis
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2
Warmouth
(Lepomis gulosus)
US: AL, AR, AZ, DC, DE, FL, GA, IA, ID,
IL, IN, KS, KY, LA, MD, MI, MN, MO,
MS, NC, NJ, NM, NV, NY, OH, OK, OR,
PA, SC, TN, TX, VA, WA, WI, WV
WW
Lentic
Lotic
Piscivore
Invertivore
TL3/4
Map: https://nas.er,usas.aov/queries/FactSheet.aspx?SpeciesID=376
.102803/Lepomis aulosus
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2
Orangespotted
Sunfish
(Lepomis humilis)
US: AL, AR, CO, FL, GA, IA, IL, IN, KS,
KY, LA, MI, MN, MO, MS, ND, NE, OH,
OK, PA, SD, TN, TX, WI, WV
WW
Lentic
Lotic
Invertivore
TL3
Map: https://nas.er,usas.aov/aueries/FactSheet.aspx?SpeciesID=383
68
-------
Name
(Common,
Scientific)
Distribution
Habitat
(WW/CW)
Lentic/Lotic
Adult Diet/
Trophic
Level
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2.103679/Lepomis humilis
Redspotted Sunfish
(Lepomis miniatus)
US: AL, AR, IL, IN, KY, LA, MO, MS,
OK, TN, TX
WW
Lentic
Lotic
Invertivore
TL3
Map: https://nas.er.usas.aov/aueries/FactSheet.aspx?SpeciesID=391
,105029/Lepomis miniatus
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GL0BAL.2
Bantam Sunfish
(Lepomis
symmetricus)
US: AR, IL, IN, KY, LA, MO, MS, OK,
TN, TX
WW
Lentic
Lotic
Invertivore
Molluscivore
TL3
Map & Info:
https://explorer.natureserve.ora/Taxon/ELEMENT GL0BAL.2.103718/Lepomis svmmetricus
Northern Longear
Sunfish
(Lepomis peltastes)
US: IL, IN, MI, MN, NY, OH, PA
WW
Lentic
Lotic
Invertivore
TL3
Map & Info:
https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2.883965/Lepomis peltastes
Spotted Sunfish
(Lepomis punctatus)
US: FL, GA, NC, SC, TN
WW
Lentic
Lotic
Invertivore
TL3
Map & Info:
https://explorer.natureserve.ora/Taxon/ELEMENT GL0BAL.2.100708/Lepomis punctatus
Other Centrarchids
Largemouth Bass
(Microptenis
sctlmoides)
US: AL, AR, AZ, CA, CO, CT, DC, DE,
FL, GA, IA, ID, IL, IN, KS, KY, LA, MA,
MD, ME, MI, MN, MO, MS, MT, NC, ND,
NE, NH, NJ, NM, NN, NV, NY, OH, OK,
OR, PA, RI, SC, SD, TN, TX, UT, VA, VT,
WA, WI, WV, WY
WW
Lentic
Lotic
Piscivore
TL4
69
-------
Name
(Common,
Scientific)
Distribution
Habitat
(WW/CW)
Lentic/Lotic
Adult Diet/
Trophic
Level
Map: https://nas.er .usas.aov/queries/FactSheet.aspx?SpeciesID=401
>2/Micropterus salmoides
Info:
https://explorer.natureserve.ore/Taxon/ELEMENT GLOBAL.2.1016;
Smallmouth Bass
(Micropterus
dolomieu)
US: AL, AR, AZ, CA, CO, CT, DC, DE,
GA, IA, ID, IL, IN, KS, KY, MA, MD, ME,
MI, MN, MO, MS, MT, NC, ND, NE, NH,
NJ, NM, NN, NV, NY, OH, OK, OR, PA,
RI, SC, SD, TN, TX, UT, VA, VT, WA,
WI, WV, WY
WW
Lentic
Lotic
Piscivore
TL4
Map: https://nas.er .usas.aov/aueries/FactSheet.aspx?SpeciesID=396
^6/Micropterus dolomieu
Info:
https://explorer.natureserve.ora/Taxon/ELEMENT GL0BAL.2.1047i
Spotted Bass
(Micropterus
punctulatus)
US: AL, AR, AZ, CA, FL, GA, IA, IL, IN,
KS, KY, LA, MO, MS, NC, NE, NM, NV,
OH, OK, PA, TN, TX, VA, WV
WW
Lentic
Lotic
Piscivore
TL4
Map: https://nas.er,usas.aov/aueries/FactSheet.aspx?SpeciesID=397
)2/Micropterus punctulatus
Info:
https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2.8722:
White Crappie
(Pomoxis annularis)
US: AL, AR, AZ, CA, CO, DC, DE, FL,
GA, IA, ID, IL, IN, KS, KY, LA, MA, MD,
MI, MN, MO, MS, MT, NC, ND, NE, NH,
NJ, NM, NN, NV, NY, OH, OK, OR, PA,
SD, TN, TX, UT, VA, VT, WA, WI, WV,
WY
WW
Lentic
Lotic
Invertivore
Piscivore
TL3
Map: https://nas.er,usas.aov/aueries/FactSheet.aspx?SpeciesID=408
106200/Pomoxis annularis
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GL0BAL.2
Black Crappie
(Pomoxis
nigromaculatus)
US: AL, AR, AZ, CA, CO, CT, DC, DE,
FL, GA, IA, ID, IL, IN, KS, KY, LA, MA,
MD, ME, MI, MN, MO, MS, MT, NC, ND,
NE, NH, NJ, NM, NV, NY, OH, OK, OR,
PA, RI, SC, SD, TN, TX, UT, VA, VT,
WA, WI, WV, WY
WW
Lentic
Lotic
Invertivore
Piscivore
TL3
70
-------
Name
(Common,
Scientific)
Distribution
Habitat
(WW/CW)
Lentic/Lotic
Adult Diet/
Trophic
Level
Map: https://nas.er.usas.aov/queries/FactSheet.aspx?SpeciesID=409
34/Pomoxis nieromaculatus
Info:
https://explorer.natureserve.ore/Taxon/ELEMENT GLOBAL.2.10311
Rock Bass
(Ambloplites
mpestris)
US: AL, AR, AZ, CT, DC, DE, GA, IA, IL,
IN, KS, KY, MA, MD, MI, MN, MO, MS,
MT, NC, ND, NE, NH, NJ, NM, NY, OH,
OK, PA, RI, SC, SD, TN, TX, VA, VT,
WA, WI, WV, WY
WW
Lentic
Lotic
Invertivore
Molluscivore
Piscivore
TL3/TL4
Map: https://nas.er .uses.eov/aueries/FactSheet.aspx?SpeciesID=373
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2.105635/Ambloplites rupestris
* Species documented to consume invasive zebra mussels and quagga mussels in the genus Dreissena by the Army
Corps of Engineers (Kirk, 2001).
71
-------
3. Salmonicls, including brown, rainbow, cutthroat trout and whitefish
Trout is the common name for species of freshwater fish belonging to the genera Oncorhynchus, Salmo
and Salvelinus in the family Salmonidae. Trout are considered cold water fish and are usually found in
clear streams, rivers and lakes with temperatures not exceeding 60°F (16°C).
Table D-3. Species in the family Salmonidae that may be sampled for implementation of the
selenium criterion.
Name
(Common,
Scientific)
Distribution
Habitat
(WW/CW)
Lentic/Lotic
Adult Diet/
Trophic
Level
Family Salmonidae
Brown Trout
{Salmo tmtta)
US: AL, AR, AZ, CA, CO, CT, DC, DE,
GA, IA, ID, IL, IN, KY, MA, MD, ME, MI,
MN, MO, MT, NC, ND, NE, NH, NJ, NM,
NN, NV, NY, OH, OK, OR, PA, RI, SD,
TN, UT, VA, VT, WA, WI, WV, WY
CW
Lentic
Lotic
Invertivore
Molluscivore
Piscivore
TL3/TL4
Man: https://nas.er .uses.20v/aueries/FactSheet.aspx?SpeciesID=931
..103603/Salmo trutta
Info: https://explorer.natureserve.ors/Taxon/ELEMENT GLOBAL.2
Rainbow Trout
(iOncorhynchus
mykiss)
US: AK, AL, AR, AZ, CA, CO, CT, DE,
GA, HI, IA, ID, IL, IN, KS, KY, MA, MD,
ME, MI, MN, MO, MS, MT, NC, ND, NE,
NH, NJ, NM, NN, NV, NY, OH, OK, OR,
PA, RI, SD, TN, TX, UT, VA, VT, WA,
WI, WV, WY
CW
Lentic
Lotic
Invertivore
Piscivore
TL3/TL4
Map: https://nas.er.usas.aov/queries/FactSheet.aspx?SpeciesID=910
54/Oncorhvnchus mvkiss
Info:
https://explorer.natureserve.ors/Taxon/ELEMENT GLOBAL.2.1051(
Cutthroat Trout
(iOncorhynchus
clarkii)
US: AK, AR, AZ, CA, CO, ID, MD, MT,
ND, NM, NN, NV, OR, UT, WA, WY
CW
Lotic
Invertivore
TL3
Map: https://nas.er .usss.sov/queries/FactSheet.aspx?SpeciesID=890
.10388 8/Oncorhvnchus clarkii
Info: https://explorer.natureserve.ore/Taxon/ELEMENT GLOBAL.2
Dolly Varden
0Salvelinus malma)
US:AK, NV, NM, WA, WY
CW
Lentic
Lotic
Invertivore
Molluscivore
Piscivore
72
-------
Name
(Common,
Scientific)
Distribution
Habitat
(WW/CW)
Lentic/Lotic
Adult Diet/
Trophic
Level
TL3/TL4
Map: https://nas.er .usas.aov/queries/FactSheet.aspx?SpeciesID=941
,104555/Salvelinus malma
Info: https://explorer.natureserve.ore/Taxon/ELEMENT GL0BAL.2
Brook Trout
(Salvelimis fontinalis)
US: AK, AR, AZ, CA, CO, CT, DE, GA,
IA, ID, IL, IN, KY, MA, MD, ME, MI,
MN, MT, NC, ND, NE, NH, NJ, NM, NN,
NV, NY, OH, OR, PA, RI, SC, SD, TN,
UT, VA, VT, WA, WI, WV, WY
CW
Lentic
Lotic
Invertivore
TL3
Map: https://nas.er .usas.aov/queries/FactSheet.aspx?SpeciesID=939
.. 103972/Salvclinus fontinalis
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.^
Mountain Whitefish
(Prosopium
williamsoni)
US: CA, CO, ID, MT, NV, OR, UT, WA,
WY
CW
Lentic
Lotic
Invertivore
Piscivore
TL3
Map: https://nas.er,usas.aov/aueries/FactSheet.aspx?SpeciesID=924
)6/Prosopium williamsoni
Info:
https://explorer.natureserve.ora/Taxon/ELEMENT GL0BAL.2.1046'
Round Whitefish
(Prosopium
cylindrctceum)
US: AK, CT, IL, ME, MI, MN, NH, NY,
VT, WI
CW
Lentic
Lotic
Invertivore
TL3
Map: https://nas.er,usas.aov/aueries/FactSheet.aspx?SpeciesID=921
UVProsopium cvlindraceum
Info:
https://explorer.natureserve.ora/Taxon/ELEMENT GL0BAL.2.1023J
Lake Whitefish*
(Coregonus
clupeiformes)
US: AK, ID, IL, IN, ME, MI, MN, MT,
ND, NH, NV, NY, OH, PA, SD, VT, WA,
WI
CW
Lentic
Lotic
Invertivore
TL3
Map: https://nas.er,usas.aov/aueries/FactSheet.aspx?SpeciesID=887
Info:
https://explorer.natureserve.ora/Taxon/ELEMENT GL0BAL.2.105498/Coreaonus clupeaformis
* Species documented to consume invasive zebra mussels and quagga mussels in the genus Dreissena by the Army
Corps of Engineers (Kirk, 2001).
73
-------
4. Freshwater Molluscivores and Related Genera
Molluscivorous fish feed either preferentially or opportunistically on a variety of mollusks (e.g., clams,
mussels and snails) in freshwater systems. Although taxonomically diverse, physiologically these fish are
adapted to feed on mollusks due to the presence of teeth or plates on the lower (and in some species
upper) pharyngeal jaws, as well as mouth gape and jaw muscle structure that accommodates feeding on
mollusks (Eastman 1977). A study by the Army Corps of Engineers (Kirk, 2001) documents at least 17
species* of North American fish that consume invasive zebra mussels and quagga mussels in the genus
Dreissena. Several of these species are sunfish in the genus Lepomis; they are presented in the table
addressing sunfish. Molluscivores may have elevated exposure to selenium, as mollusks bioaccumulate
more selenium than other classes of aquatic invertebrates. These taxa typically inhabit larger warm water
lentic and lotic systems.
Table D-4. Molluscivores and related genera that may be sampled for implementation of the
selenium criterion.
Name
(Common,
Scientific)
Distribution
Habitat
(WW/CW)
Lentic/Lotic
Adult Diet/
Trophic
Level
Freshwater Molluscivores
Freshwater Drum*
(Aplodinotus grunniens)
US: AL, AR, CO, GA, IA, IL, IN, KS,
KY, LA, MI, MN, MO, MS, MT, NC,
ND, NE, NM, NY, OH, OK, PA, SD,
TN, TX, VA, VT, WI, WV, WY
WW
Lentic
Lotic
Invertivore
Piscivore
Molluscivore
TL4
Man: https://nas.er .usas.aov/aueries/FactSheet.aspx?SpeciesID=946
38/Aplodinotus arunniens
Info:
https://explorer.natureserve.ore/Taxon/ELEMENT GLOBAL.2.1003;
White Perch*
(Morone americana)
US: CO, CT, DC, DE, GA, IN, MA,
MD, ME, MI, NC, NE, NH, NJ, NY, PA,
RI, VA, VT, WI
WW
Lentic
Lotic
Estuarine
Invertivore
Molluscivore
Piscivore
TL4
Map: https://nas.er .usas.aov/queries/FactSheet.aspx?SpeciesID=777
10043 6/Morone americana
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GL0BAL.2
White bass*
(Morone chtysops)
US: AL, AR, AZ, CA, CO, DC, FL, GA,
IA, IL, IN, KS, KY, LA, MD, MI, MN,
MO, MS, MT, NC, ND, NE, NM, NV,
NY, OH, OK, PA, SC, SD, TN, TX, UT,
VA, WI, WV
WW
Lentic
Lotic
Piscivore
Invertivore
Molluscivore
TL4
Map: https://nas.er,usas.aov/aueries/FactSheet.aspx?SpeciesID=779
74
-------
Name
(Common,
Scientific)
Distribution
Habitat
(WW/CW)
Lentic/Lotic
Adult Diet/
Trophic
Level
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2.100951/Morone chrvsops
Round Goby*
(Neogobius
melanostomus)
US: IL, IN, MI, MN, NY, OH, PA, WI
WW
Lentic
Lotic
Piscivore
Invertivore
Molluscivore
TL3
Map: https://nas.er.usas.aov/aueries/FactSheet.aspx?SpeciesID=713
)l/Neoaobius melanostomus
Info:
https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2.1005(
Brown Bullhead*
(Ameiurus nebulosus)
US: AL, AR, AZ, CA, CO, CT, DC, DE,
FL, GA, IA, ID, IL, IN, KS, KY, LA,
MA, MD, ME, MI, MN, MO, MS, NC,
ND, NE, NH, NJ, NM, NV, NY, OH,
OK, OR, PA, RI, SC, SD, TN, TX, VA,
VT, WA, WI, WV
WW
Lentic
Lotic
Omnivore
Molluscivore
TL3
Map: https://nas.er .usas.aov/queries/FactSheet.aspx?SpeciesID=734
!. 103081/Ameiurus nebulosus
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2
Yellow Perch*
(Percci flcivescens)
US: AL, AZ, CA, CO, CT, DC, DE, FL,
GA, IA, ID, IL, IN, KS, KY, MA, MD,
ME, MI, MN, MO, MS, MT, NC, ND,
NE, NH, NJ, NM, NN, NV, NY, OH,
OK, OR, PA, RI, SC, SD, TX, UT, VA,
VT, WA, WI, WV, WY
WW
Lentic
Lotic
Invertivore
Piscivore
Molluscivore
TL4
Map: https://nas.er,usas.aov/aueries/FactSheet.aspx?SpeciesID=820
.. 102985/Perca flavescens
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2
Common carp*
(Cyprinus cctrpio)
US: AL, AR, AZ, CA, CO, CT, DC, DE,
FL, GA, IA, ID, IL, IN, KS, KY, LA,
MA, MD, ME, MI, MN, MO, MS, MT,
NC, ND, NE, NH, NJ, NM, NN, NV,
NY, OH, OK, OR, PA, RI, SC, SD, TN,
TX, UT, VA, VT, WA, WI, WV, WY
WW
Lentic
Lotic
Omnivore
Molluscivore
TL3
Map: https://nas.er,usas.aov/aueries/FactSheet.aspx?SpeciesID=4
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2.105636/Cvprinus carpio
75
-------
Name
(Common,
Scientific)
Distribution
Habitat
(WW/CW)
Lentic/Lotic
Adult Diet/
Trophic
Level
Catostomidae
Smallmouth Buffalo
(Ictiobus bubalus)
US: AL, AR, AZ, GA, IA, IL, IN, KS,
KY, LA, MI, MN, MO, MS, MT, NC,
ND, NE, NM, OH, OK, PA, SD, TN,
TX, WI, WV
WW
Lentic
Lotic
Herbivore
Invertivore
Molluscivore
TL3
Map: https://nas.er.usas.aov/aueries/factsheet.aspx?SpeciesID=361
.105191 /Ictiobus bubalus
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GL0BAL.2
Black Buffalo
(Ictiobus niger)
US: AL, AR, AZ, GA, IA, IL, IN, KS,
KY, LA, MI, MN, MO, MS, NC, ND,
NE, OH, OK, PA, SD, TN, TX, WI, WV
WW
Lentic
Lotic
Herbivore
Invertivore
Molluscivore
TL3
Map: https://nas.er .usas.aov/queries/FactSheet.aspx?SpeciesID=363
,101227/Ictiobus niaer
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GL0BAL.2
White sucker*
0Ccitostomus
commersoni)
US: AL, AR, CO, CT, DC, DE, GA, IA,
IL, IN, KS, KY, MA, MD, ME, MI, MN,
MO, MT, NC, ND, NE, NH, NJ, NM,
NN, NY, OH, OK, PA, RI, SC, SD, TN,
UT, VA, VT, WI, WV, WY
WW
Lentic
Lotic
Herbivore
Molluscivore
Invertivore
TL3
Map: https://nas.er,usas.aov/queries/FactSheet.aspx?SpeciesID=346
)7/Catostomus commersonii
Info:
https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2.8332(
Largescale Sucker
{Ccitostomus
macrocheilus)
US: ID, MT, NV, OR, WA
CW
Lentic
Lotic
Herbivore
Invertivore
Molluscivore
TL3
Map & Info:
https://explorer.natureserve.ora/Taxon/ELEMENT GL0BAL.2.1098871/Catostomus macrocheilus
76
-------
Name
(Common,
Scientific)
Distribution
Habitat
(WW/CW)
Lentic/Lotic
Adult Diet/
Trophic
Level
Greater Redhorse*
(Moxostomct
valencienni)
US: IL, IN, KY, MI, MN, ND, NY, OH,
VT,WI
WW
Lentic
Lotic
Invertivore
Molluscivore
TL3
Map & Info:
https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2.101488/Moxostoma valenciennesi
Shorthead Redhorse
{Moxostomct
macrolepidutum)
US: DC, DE, IA, IL, IN, KS, MD, MI,
MN, MO, MS, MT, NC, ND, NE, NY,
OH, OK, PA, SC, SD, TX, VA, VT, WI,
WV, WY
WW
Lentic
Lotic
Invertivore
Molluscivore
TL3
Map: https://nas.er.usas.aov/aueries/FactSheet.aspx?SpeciesID=366
1/Moxostoma macrolepidotu
Info:
https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2.7914
m
River Redhorse
{Moxostomct ccirincitum)
US: AL, AR, FL, GA, IA, IL, IN, KS,
KY, LA, MI, MN, MO, MS, NC, NY,
OH, OK, PA, TN, VA, WI, WV
WW
Lotic
Invertivore
Molluscivore
TL3
Map & Info:
https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2.106031/Moxostoma carinatum
Golden redhorse
{Moxostomct
erythnirum)
US: AL, AR, DC, GA, IA, IL, IN, KS,
KY, MD, MI, MN, MO, MS, NC, ND,
NY, OH, OK, PA, SD, TN, TX, VA, WI,
WV
WW
Lotic
Invertivore
Molluscivore
TL3
Map: https://nas.er,usas.aov/aueries/FactSheet.aspx?SpeciesID=365
78/Moxostoma ervthrurum
Info:
https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2.1007'
Silver Redhorse
{Moxostomct ctnisariim)
US: AL, AR, GA, IA, IL, IN, KY, MI,
MN, MO, MS, ND, NY, OH, PA, TN,
VA, VT, WI, WV
WW
Lotic
Invertivore
Molluscivore
TL3
Map: https://nas.er,usas.aov/queries/FactSheet.aspx?SpeciesID=2912
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2.100712/Moxostoma anisurum
77
-------
* Species documented to consume invasive zebra mussels and quagga mussels in the genus Dreissena by the Army
Corps of Engineers (Kirk, 2001).
78
-------
5. Minnows (Cyprinidae)
The family Cyprinidae (carps and minnows) is naturally distributed throughout most of the world and is
the largest family of freshwater fishes with about 2,010 species in 210 genera. About 300 species in 50
genera are native to North America (Canada, Mexico, United States; Nelson, 2006). Cyprinids exhibit
considerable variation in morphology, diet, and habitat use, and are often the only fish taxa (along with
darters and sculpins) occurring in small order streams. Although cyprinids are not typically considered
monitoring targets for contaminant analysis in their tissues, they are routinely collected as part of state
biomonitoring programs that use the fish index of biotic integrity to assess stream health in wadeable
streams.
EPA recommends that fish tissue monitoring programs collaborate with state or tribal biomonitoring
programs to leverage expertise, experience and resources to collect cyprinids and related species in
watersheds located in geographic areas of elevated selenium where anthropogenic activities may
introduce selenium to surface waters if other more sensitive species are not present.
Table D-5. Species in the family Cyprinidae that may be sampled for implementation of the
selenium criterion.
Name
(Common,
Scientific)
Distribution
Habitat
(WW/CW)
Lentic/Lotic
Adult Diet/
Trophic Level
Fathead Minnow
(Pimephcdes promelas)
US: AL, AR, AZ, CA, CO, CT, DE, GA,
IA, ID, IL, IN, KS, KY, LA, MA, MD,
ME, MI, MN, MO, MS, MT, NC, ND,
NE, NH, NM, NN, NV, NY, OK, OR,
PA, SD, TN, TX, UT, VA, VT, WA, WI,
WV, WY
WW
Lentic
Lotic
Herbivore
Invertivore
TL3
Map: https://nas.er.usas.aov/queries/FactSheet.aspx?SpeciesID=621
..102599/Pimephales promelas
Info: https://explorer.natureserve.ore/Taxon/ELEMENT GLOBAL.^
Bluntnose Minnow
(Pimephcdes notatus)
US: AL, AR, CT, DC, GA, IA, IL, IN,
KS, KY, LA, MA, MD, MI, MN, MO,
MS, NC, ND, NE, NJ, NY, OH, OK, PA,
SD, TN, VA, VT, WI, WV
WW
Lotic
Lentic
Herbivore
Invertivore
TL3
Man: https://nas.er .uses.2ov/aueries/FactSheet.aspx?SpeciesID=620
..103436/Pimephales notatus
Info: https://explorer.natureserve.ore/Taxon/ELEMENT GLOBAL.^
Bullhead Minnow
(Pimephcdes vigilctx)
US: AL, AR, CO, GA, IA, IL, IN, KS,
KY, LA, MN, MO, MS, NE, NM, OH,
OK, PA, SD, TN, TX, VA, WI,
WW
Lentic
Lotic
Herbivore
Invertivore
TL3
Map: https://nas.er.usss.sov/aueries/FactSheet.aspx?SpeciesID=623
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2.106123/Pimephales viailax
79
-------
Name
(Common,
Scientific)
Distribution
Habitat
(WW/CW)
Lentic/Lotic
Adult Diet/
Trophic Level
Cutlip Minnow
(Exoglossum
maxillingua)
US: CT, DC, DE, MD, NC, NJ, NY, PA,
VA, VT, WV
WW
Lotic
Invertivore
Molluscivore
TL3
Man: https://nas.er .usas.aov/aueries/FactSheet.aspx?SpeciesID=530
9/Exoalossum maxillinaua
Info:
https://explorer.natureserve.ore/Taxon/ELEMENT GL0BAL.2.1027
Suckermouth Minnow
(Phencicobius mirabilis)
US: AL, AR, CO, IA, IL, IN, KS, KY,
LA, MI, MN, MO, MS, NE, NM, OH,
OK, SD, TN, TX, VA, WI, WV, WY
WW
Lotic
Herbivore
Invertivore
TL3
Map: https://nas.er.usas.aov/aueries/FactSheet.aspx?SpeciesID=617
,104716/Phenacobius mirabilis
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2
Blackstripe Topminnow
(Fundulus notatus)
US: AL, AR, IA, IL, IN, KS, KY, LA,
MI, MO, MS, OH, OK, TN, TX, WI
WW
Lentic
Lotic
Herbivore
Invertivore
Molluscivore
TL3
Map: https://nas.er .usas.aov/aueries/FactSheet.aspx?SpeciesID=690
,100269/Fundulus notatus
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GL0BAL.2
Starhead Topminnow
(Fundulus dispctr)
US: AL, AR, FL, IA, IL, IN, KY, LA,
MI, MO, MS, OK, TN, WI
WW
Lentic
Lotic
Invertivore
Molluscivore
TL3
Map & Info: https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2.105342/Fundulus dispar
Western Blacknose
Dace
(Rhinichthys obtusus)
US: AL, GA, IA, IL, IN, KS, KY, MI,
MN, MO, MS, NC, ND, NE, NY, OH,
PA, SC, SD, TN, VA, WI, WV
CW
Lotic
Invertivore
TL3
Map & Info:
https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2.790464/Rhinichthvs obtusus
80
-------
Name
(Common,
Scientific)
Distribution
Habitat
(WW/CW)
Lentic/Lotic
Adult Diet/
Trophic Level
Eastern Blacknose Dace
(Rhinichthys atratalus)
US: CT, DC, DE, GA, MA, MD, ME,
NC, NH, NJ, NY, PA, RI, VA, VT, WV
CW
Lotic
Invertivore
TL3
Map: https://nas.er.usas.aov/aueries/FactSheet.aspx?SpeciesID=637
,828296/Rhinichthvs atratulus
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2
Longnose Dace
(Rhinichthys cataractae)
US: CO, CT, DC, DE, GA, IA, ID, IL,
IN, MA, MD, ME, MI, MN, MT, NC,
ND, NE, NH, NJ, NM, NV, NY, OH,
OR, PA, RI, SC, SD, TN, TX, UT, VA,
VT, WA, WI, WV, WY
CW
Lentic
Lotic
Invertivore
TL3
Map: https://nas.er .usas.aov/aueries/FactSheet.aspx?SpeciesID=638
,101847/Rhinichthvs cataractae
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2
Finescale Dace
0Chrosomus neogcteus)
US: ME, MI, MN, ND, NE, NH, NY,
SD, VT, WI, WY
WW
Lentic
Lotic
Invertivore
Molluscivore
TL3
Map: https://nas.er,usas.aov/queries/FactSheet.aspx?SpeciesID=2556
.102927/Chrosomus neoaaeus
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GL0BAL.2
Speckled Dace
(Rhinichthys osculus)
US: AZ, CA, CO, ID, NM, NN, NV,
OR, UT, WA, WY
CW
Lotic
Invertivore
TL3
Map: https://nas.er.usas.aov/queries/FactSheet.aspx?SpeciesID=640
100335/Rhinichthvs osculus
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GL0BAL.2
Satinfin Shiner
(Cyprinella ancdostana)
US: DC, DE, MD, NC, NJ, NY, PA,
WW
Lotic
Invertivore
TL3
Map: https://nas.er,usas.aov/aueries/FactSheet.aspx?SpeciesID=516
.106108/Cvprinella analostana
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GL0BAL.2
Red Shiner
(Cyprinella lutrensis)
US: AL, AR, AZ, CO, GA, IA, IL, IN,
KS, KY, LA, MN, MO, MS, NC, ND,
NE, NM, NN, NV, OK, SD, TN, TX,
WW
Lentic
Lotic
Invertivore
TL3
81
-------
Name
(Common,
Scientific)
Distribution
Habitat
(WW/CW)
Lentic/Lotic
Adult Diet/
Trophic Level
Mao: https://nas.er.usas.aov/aueries/FactSheet.aspx?SpeciesID=518
.105504/Cvprinella lutrensis
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2
Bigmouth Shiner
(Notropis dorsctlis)
US: CO, IA, IL, IN, KS, MI, MN, MO,
ND, NE, NY, OH, PA, SD, TN, WI,
WV, WY
WW
Lotic
Invertivore
TL3
Map: https://nas.er.usas.aov/aueries/FactSheet.aspx?SpeciesID=593
,104308/Notropis dorsalis
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GL0BAL.2
Chub Shiner
(Notropis potteri)
US: AR, LA, OK, TX
WW
Lentic
Lotic
Invertivore
Piscivore
TL3
Map: https://nas.er .usas.aov/aueries/FactSheet.aspx?SpeciesID=606
,105179/Notropis potteri
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GL0BAL.2
Sand Shiner
(Notropis stramineus)
US: AR, AZ, CO, IA, IL, IN, KS, KY,
MI, MN, MO, MT, ND, NE, NM, NN,
NY, OH, OK, PA, SD, TN, TX, UT, VA,
VT, WI, WV, WY
WW
Lentic
Lotic
Invertivore
TL3
Map: https://nas.er.usas.aov/aueries/FactSheet.aspx?SpeciesID=600
104717/Notropis stramineus
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GL0BAL.2
Redside Shiner
(Richardsonius
bcdteatiis)
US: AZ, CO, ID, MT, NV, OR, UT,
WA. WY
CW
Lentic
Lotic
Herbivore
Invertivore
Molluscivore
Piscivore
TL3
Map: https://nas.er,usas.aov/aueries/FactSheet.aspx?SpeciesID=644
.100279/Richardsonius balteatus
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GL0BAL.2
Thicklip Chub
(Cyprinella labrosa)
US: NC, SC, VA
WW
Lotic
Invertivore
Molluscivore
TL3
82
-------
Name
(Common,
Scientific)
Distribution
Habitat
(WW/CW)
Lentic/Lotic
Adult Diet/
Trophic Level
Map & Info:
https://explorer.natureserve.org/Taxon/ELEMENT GL0BAL.2.101215/Cvprinella labrosa
Streamline Chub
(Erimystax dissimilis)
US: AL, IN, KY, NY, OH, PA, TN, VA,
WV
WW
Lotic
Invertivore
Molluscivore
TL3
Map: & Info:
https://explorer.natureserve.org/Taxon/ELEMENT GL0BAL.2.106034/Erimvstax dissimilis
Shoal Chub
(Mctcrhybopsis
hyostoma)
US: AL, AR, IA, IL, IN, KS, KY, LA,
MN, MO, MS, NE, OH, OK, TN, TX,
WI,WV
WW
Lotic
Invertivore
TL3
Map & Info:
https://explorer.natureserve.org/Taxon/ELEMENT GL0BAL.2.106278/Macrhvbopsis hyostoma
Silver Chub
(Mctcrhybopsis
storeriana)
US: AL, AR, GA, IA, IL, IN, KS, KY,
LA, MI, MN, MO, MS, ND, NE, NY,
OH, OK, PA, SD, TN, TX, WI, WV
WW
Lotic
Invertivore
Molluscivore
TL3
Map:
Info:
https://explorer.natureserve.org/Taxon/ELEMENT GL0BAL.2.101653/Macrhvbopsis storeriana
River Chub
(Nocomis micropogon)
US: AL, DC, GA, IL, IN, KY, MD, MI,
NC, NY, OH, PA, SC, TN, VA, WV
WW
Lotic
Invertivore
Molluscivore
TL3
Map: https://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=577
Info: https://explorer.natureserve.org/Taxon/ELEMENT GL0BAL.2.101786/Nocomis micropogon
Bull Chub*
(Nocomis ranevi)
US: NC, VA
WW
Lotic
Herbivore
Invertivore
Molluscivore
TL3
Map & Info: https://explorer.natureserve.org/Taxon/ELEMENT GLOBAL.2.1Q1374/Nocomis ranevi
83
-------
Name
(Common,
Scientific)
Distribution
Habitat
(WW/CW)
Lentic/Lotic
Adult Diet/
Trophic Level
Peamouth
(Mylocheilus ccnirimis)
US: ID, MT, OR, WA
CW
Lentic
Lotic
Invertivore
Molluscivore
Piscivore
TL3
Map: https://nas.er .usas.aov/queries/FactSheet.aspx?SpeciesID=2349
.100544/Mvlocheilus caurinus
Info: https://explorer.natureserve.ore/Taxon/ELEMENT GL0BAL.2
Creek Chub
(Semotilus
atromacidatiis)
US: AL, AR, CO, CT, DC, DE, FL, GA,
IA, IL, IN, KS, KY, LA, MA, MD, ME,
MI, MN, MO, MS, MT, NC, ND, NE,
NH, NJ, NM, NY, OH, OK, PA, SC, SD,
TN, TX, UT, VA, VT, WI, WV, WY
WW
Lotic
Invertivore
Piscivore
TL3
Map: https://nas.er .usas.aov/aueries/FactSheet.aspx?SpeciesID=649
57/Semotilus atromaculatus
Info:
https://explorer.natureserve.ora/Taxon/ELEMENT GL0BAL.2.1048(
Central Stoneroller
{Campostoma
anomaliim)
US: AR, CO, CT, GA, IA, IL, IN, KS,
KY, LA, MD, MI, MN, MO, MS, NC,
ND, NE, NM, NY, OH, OK, PA, SC,
SD, TN, TX, VA, WI, WV, WY
WW
Lotic
Herbivore
Map: https://nas.er.usas.aov/aueries/FactSheet.aspx?SpeciesID=506
W/Campostoma anomalum
Info:
https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2.844 U
Largescale Stoneroller
{Campostoma
oligolepis)
US: AL, AR, GA, IA, IL, IN, KY, MN,
MO, MS, ND, OK, VA, WI
WW
Lotic
Herbivore
Map: https://nas.er .usas.aov/queries/FactSheet.aspx?SpeciesID=507
.102552/Campostoma oliaolepis
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GL0BAL.2
Sacramento Splittail
(Pogonichthvs
macrolepidotiis)
US: CA
WW
Lotic
Estuarine
Herbivore
Invertivore
84
-------
Name
(Common,
Scientific)
Distribution
Habitat
(WW/CW)
Lentic/Lotic
Adult Diet/
Trophic Level
Map & Info:
https://explorer.natureserve.ora/Taxon/ELEMENT GL0BAL.2.105438/Poaonichthvs macrolepidotus
* Species documented to consume invasive zebra mussels and quagga mussels in the genus Dreissena by the Army
Corps of Engineers (Kirk, 2001).
85
-------
6. Darters (Percidae)
Darters are small, perch-like fish in the family Percidae and are found in freshwater streams in North
America. Darters typically occur in riverine systems, inhabiting cold to cool streams and small river
systems in North America. Species distributions range from single watersheds in one state to multiple
watersheds in several states. Darters are typically benthic omnivores, practicing herbivory as well as
preying on invertebrates and for some species, small fish and fish eggs as well.
Table D-6. Species in the family Percidae that may be sampled for implementation of the selenium
criterion.
Name
(Common,
Scientific)
Distribution
Habitat
(WW/CW)
Lentic/Lotic
Adult Diet/
Trophic Level
Greenside Darter
(Etheostoma blennioides)
US: AL, AR, DC, GA, IL, IN,
KS, KY, MD, MI, MO, MS, NC,
NY, OH, OK, PA, TN, VA, WV
WW
Lotic
Lentic
Invertivore
TL3
Man: https://nas.er .usas.aov/aueries/FactSheet.aspx?SpeciesID=808
oma blennioides
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2.790349/Etheost
Arkansas Darter
(Etheostoma crctgini)
US: AR, CO, KS, MO, OK
WW
Lotic
Invertivore
Molluscivore
TL3
Map: https://nas.er.usas.aov/aueries/FactSheet.aspx?SpeciesID=810
oma craaini
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GL0BAL.2.103800/Etheost
Iowa Darter
(Etheostoma exile)
US: CO, IA, IL, IN, MI, MN,
MT, ND, NE, NM, NY, OH, PA,
SD, UT, WI, WY
WW
Lotic
Invertivore
TL3
Map: https://nas.er .usas.aov/aueries/FactSheet.aspx?SpeciesID=812
oma exile
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2.100441/Etheost
Fantail Darter
(Etheostoma flabellare)
US: AL, AR, DC, IA, IL, IN, KS,
KY, MD, MI, MN, MO, MS, NC,
NY, OH, OK, PA, SC, TN, VA,
VT, WI, WV
WW
Lotic
Invertivore
TL3
Map & Info:
https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2.832912/Etheostoma flabellare
86
-------
Name
(Common,
Scientific)
Distribution
Habitat
(WW/CW)
Lentic/Lotic
Adult Diet/
Trophic Level
Least Darter
(Etheostoma micropercct)
US: AR, IA, IL, IN, KS, KY, MI,
MN, MO, OH, OK, WI
WW
Lotic
Invertivore
TL3
Map & Info:
https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2.103616/Etheostoma microperca
Johnny Darter
(Etheostoma nigrum)
US: AL, AR, CO, IA, IL, IN, KS,
KY, MD, MI, MN, MO, MS, NC,
ND, NE, NY, OH, OK, PA, SD,
TN, UT, VA, WI, WV, WY
WW
Lotic
Lentic
Invertivore
TL3
Map: https://nas.er.usas.aov/aueries/FactSheet.aspx?SpeciesID=814
oma niarum
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2.100152/Etheost
Tessellated Darter
(Etheostoma olmstedi)
US: CT, DC, DE, FL, GA, MA,
MD, NC, NH, NJ, NY, PA, RI,
SC, VA, VT, WV
WW
Lotic
Lentic
Invertivore
TL3
Map: https://nas.er.usas.aov/aueries/FactSheet.aspx?SpeciesID=816
toma olmstedi
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2.106063/Etheos
Cypress Darter
(Etheostoma proeliare)
US: AL, AR, FL, IL, KY, LA,
MO, MS, OK, TN, TX
WW
Lotic
Lentic
Invertivore
TL3
Map & Info:
https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2.101593/Etheostoma proeliare
Redline Darter
(Etheostoma nifilineatiim)
US: AL, GA, KY, MS, NC, TN,
VA
WW
Lotic
Invertivore
TL3
Map: https://nas.er,usas.aov/aueries/FactSheet.aspx?SpeciesID=2886
ufilineatum
Info:
https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2.103471/Etheostoma r
Orangebelly Darter
(Etheostoma radiosum)
US: AR, OK, TX
WW
Lotic
Invertivore
TL3
87
-------
Name
(Common,
Scientific)
Distribution
Habitat
(WW/CW)
Lentic/Lotic
Adult Diet/
Trophic Level
Map & Info:
https://explorer.natureserve.Org/Taxon/ELEMENT_GLOBAL.2.1156842/Etheostoma_radiosum
Orangethroat Darter
(Etheostoma spectctbile)
US: AR, CO, IA, IL, IN, KS, KY,
MI, MO, NE, OH, OK, TN, TX,
WY
WW
Lotic
Invertivore
TL3
Map & Info:
https://exDlorer.natureserve.ora/Taxon/ELEMENT GL0BAL.2.102592/Etheostoma spectabile
Speckled Darter
(Etheostoma stigmcteum)
US: AL, AR, FL, GA, KY, LA,
MO, MS,
WW
Lotic
Invertivore
TL3
Map & Info:
https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2.1006953/Etheostoma stiamaeum
Gulf Darter
(Etheostoma swaini)
US: AL, FL, GA, KY, LA, MS,
TN
WW
Lotic
Invertivore
TL3
Map & Info:
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2.102176/Etheostoma swaini
Variegate Darter
(Etheostoma variatum)
US: IN, KY, NY, OH, PA, VA,
WV
WW
Lotic
Invertivore
TL3
Map: https://nas.er.usas.aov/queries/FactSheet.aspx?SpeciesID=3333
oma variatum
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GL0BAL.2.102018/Etheost
Banded Darter
(Etheostoma zonale)
US: AL, AR, GA, IA, IL, IN, KS,
KY, MD, MI, MN, MO, NC, NY,
OH,
WW
Lotic
Invertivore
TL3
Map: https://nas.er.usas.aov/aueries/FactSheet.aspx?SpeciesID=818
oma zonale
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GL0BAL.2.106576/Etheost
River Darter
(Percina shumardi)
US: AL, AR, GA, IA, IL, IN, KS,
KY, LA, MI, MN, MO, MS, ND,
OH, OK, PA, TN, TX, WI, WV
WW
Lotic
Invertivore
TL3
88
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Name
(Common,
Scientific)
Distribution
Habitat
(WW/CW)
Lentic/Lotic
Adult Diet/
Trophic Level
Mao: https://nas.er .usas.aov/aueries/FactSheet.aspx?SpeciesID=826
shumardi
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GL0BAL.2.101870/Percina
Slenderhead Darter
(Percina phoxocephala)
US: AL, AR, IA, IL, IN, KS, KY,
MN, MO, MS, OH, OK, SD, TN,
WI,WV
WW
Lotic
Invertivore
TL3
Map & Info:
https://exDlorer.natureserve.ora/Taxon/ELEMENT GL0BAL.2.104090/Percina phoxocephala
Shield Darter
(Percina peltata)
US: DC, DE, MD, NJ, NY, PA,
VA, WV
WW
Lotic
Invertivore
TL3
Map: https://nas.er,usas.aov/aueries/FactSheet.aspx?SpeciesID=2775
peltata
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2.105028/Percina
Blackbanded Darter
{Percina nigrofasciata)
US: AL, FL, GA, LA, MS, NC,
SC, TN
WW
Lotic
Invertivore
TL3
Map: https://nas.er,usas.aov/aueries/FactSheet.aspx?SpeciesID=824
niarofasciata
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GL0BAL.2.102848/Percina
Blackside Darter
{Percina maculata)
US: AL, AR, IA, IL, IN, KS, KY,
LA, MI, MN, MO, MS, ND, NE,
NY, OH, OK, PA, SD, TN, TX,
VA, WI, WV
WW
Lotic
Invertivore
TL3
Map: https://nas.er.usas.aov/aueries/FactSheet.aspx?SpeciesID=823
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2.106566/Percina maculata
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7. Sculpins (Scorpionidae)
Sculpins are members of the family Scorpionidae (Scorpionfish), and most species in the Northern
Hemisphere are saltwater fishes. Most freshwater sculpins in the US are in the genus Cottiis, and are
small benthic predators consuming mainly invertebrates. Sculpins typically prefer cooler, headwater
streams, but can be found in larger warmer streams in some states.
Table D-7. Species in the family Scorpionidae that may be sampled for implementation of the
selenium criterion.
Name
(Common,
Scientific)
Distribution
Habitat
(WW/CW)
Lentic/Lotic
Adult Diet/
Trophic Level
Mottled Sculpin
0Cottas bctirdii)
US: AL, AZ, CO, DE, GA, IA,
ID, IL, IN, KY, MD, MI, MN,
MO, MS, MT, NC, NM, NN,
NV, NY, OH, OR, PA, SC, TN,
UT, VA, VT, WA, WI, WV,
WY
CW/WW
Lotic
Lentic
Herbivore
Invertivore
Piscivore
TL3
Man: https://nas.er .usas.aov/aueries/FactSheet.aspx?SpeciesID=502
bairdii
Info: https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2.819868/Cottus
Paiute Sculpin
0Cottas beldingii)
US: CA, CO, ID, NV, OR, UT,
WA, WY
CW/WW
Lotic
Herbivore
Molluscivore
Invertivore
TL3
Map & Info: https://explorer.natureserve.ore/Taxon/ELEMENT GLOBAL.2.101884/Cottus beldingii
Banded Sculpin
0Cottas carolinae)
US: AL, AR, GA, IL, IN, KS,
KY, MO, MS, NC, OK, TN, VA
CW/WW
Lotic
Herbivore
Invertivore
Piscivore
TL3
Map & Info: https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2.819914/Cottus carolinae
Slimy Sculpin
(iCottas cognatas)
US: AK, CT, IA, ID, IL, IN,
MA, ME, MI, MN, MT, NH, NJ,
NY, PA, VA, VT, WA, WI, WV
cw
Lotic
Lentic
Herbivore
Invertivore
Piscivore
TL3
Map & Info: https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2.101449/Cottus coanatus
90
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Name
(Common,
Scientific)
Distribution
Habitat
(WW/CW)
Lentic/Lotic
Adult Diet/
Trophic Level
Shorthead Sculpin
(Cottus confuses)
US: ID, NV, OR, WA
CW
Lotic
Invertivore
TL3
Map & Info: https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2.905574/Cottus confiisus
Riffle Sculpin
('CottllS glllosus)
US: CA, OR, WA
CW
Lotic
Invertivore
Molluscivore
TL3
Map & Info: https://explorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2.103055/Cottus aulosus
Spoonhead Sculpin
{Cottus ricei)
US: IL, MI, MN, MT, NY, OH,
PA, WI
CW
Lotic
Lentic
Omnivore
Invertivore
TL3
Map &Info: https://exDlorer.natureserve.ora/Taxon/ELEMENT GLOBAL.2.103689/Cottus ricei
References:
Eastman, J. 1977. The pharyngeal bones and teeth of catostomid fish. Am. Midi. Nat. 97(1): 68-
88.
Kirk, J.P., K.J. Killgore, and L.G. Sanders. 2001. Potential of North American molluscivorous
fish to control dreissenid mussels. U.S. Army Corps of Engineers Zebra Mussel Research
Program.
Natureserve Explorer. 2020. Gainesville, VA. http s: //ex pi orer. nature serve. org/
Nelson, J. S. 2006. Fishes of the World. 4th ed. Hoboken, New Jersey: John Wiley & Sons.
U.S. Geological Survey. 2020. Nonindigenous aquatic species database, Gainesville, FL.
nas.er.usgs.gov
91
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Appendix E: Calculation of Composite Trophic Transfer Factors
Derivation of Trophic Transfer Factor (TTF) Values
The parameter jirffcor"P°slte (composite trophic transfer factor) in Equation 1 quantitatively represents all
dietary pathways of selenium exposure for a particular fish species within an aquatic system. The
parameter is derived from species-specific TTF values representing the food web characteristics of the
aquatic system and the proportion of species consumed. It is possible to differentiate bioaccumulative
potential for different predator species and food webs by modeling different exposure scenarios. For
example, where a fish species of interest is a trophic level 4 predator that primarily consumes trophic
level 3 fish, the term i"i],vomi"a"e can bc represented as the product of all TTF parameters that includes the
additional trophic level given as:
jjpcomposite _ j"ppTL4 ^ rj-,rj-'pTL3 ^ rj-,rj-'pTL2
(Equation 1)
where:
TTFTL2 = the trophic transfer factor of the trophic level 2 species
TTFru = the trophic transfer factor of the trophic level 3 species
fffTL4 = the trophic transfer factor of the trophic level 4 species
jjpcomposite — product of all the trophic transfer factors
The consumption of more than one species of organism at the same trophic level can also be modeled by
expressing the TTF at a particular trophic level as the weighted average of the TTFs of all species
consumed given as:
TTFTLX = V (TTFjLx x Wj)
i
(Equation 2)
the trophic transfer factor of the ith species at a particular trophic level
the proportion of the ith species consumed
where:
TTFjhx
Wi
Figure 1 below describes five example food web scenarios and the formulation of TTFco'"posite to
model selenium bioaccumulation in each of them.
92
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A) Three trophic levels fsimnleV
_ j.J jj 77.5
? «¦
ITF711
BI Four ti ophic levels Simple ):
jjpiMVMic _ jjpiu xjjpn3 xTTF™'3
2YpTL4
jYpTLJ
TTFn: •
O Three trophic levels fmiv mtliiu trophic levels):
jjpa-r** = jjpro x|j(j7j7r" x w,)+(nFInj x w3)]
TTF71
TTFJ12
Wj O < —
w2^ ^
ITF"
#'h
*
D) Three trophic levels univ across trophic lev els):
irF^" = (iTF1" x w,)+ {iTF mi x TTF'712 x w,)
W]
JYfH-l
W2 r - ^
TTF712
** -¦*¦
E > Four trophic levels fmiv across trophic levels'):
11 h= j(7TFn' x TTFnl «w,)+ (iTF™ x^JxTTF7"
777™ JIF™
Figure 1. Example aquatic system scenarios and the derivation of the equation parameter
jjpcomposite
93
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