vvEPA
Measuring
Coastal
Acidification
Using In Situ
Sensors in
the National
Program
U.S. Environmental Protection Agency. 2021. Measuring
Coastal Acidification Using In Situ Sensors in the
National Estuary Program. Washington D.C., Document
No. EPA-842-R-21001.
Note: All photos credited to the National Estuary
Programs identified in this report, unless otherwise noted.

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Co-Authors:
Holly Galavotti, U.S. EPA Office of Water
Barnegat Bay
Jim Vasslides, Senior Program Scientist, Barnegat Bay Partnership
Matthew Poach, NOAA NMFS Milford Laboratory
Casco Bay
Curtis Bohlen, Director, Casco Bay Estuary Partnership
Christopher W. Hunt, University of New Hampshire
Matthew Liebman, U.S. EPA Region 1
Coastal Bend Bays
Xinping Hu, Harte Research Institute for Gulf of Mexico Studies, Texas A&M University-Corpus Christi
Melissa McCutcheon, Ph.D. Candidate, Harte Research Institute for Gulf of Mexico Studies, Texas A&M
University-Corpus Christi
Long Island Sound Study
Jim Ammerman, Long Island Sound Study Science Coordinator
Jim O'Donnell, University of Connecticut
Kay Howard-Strobel, University of Connecticut
Massachusetts Bays (MassBays)
Prassede Vella, Staff Scientist, Massachusetts Bay National Estuary Partnership
Mobile Bay
John Lehrter, University of South Alabama and Dauphin Island Sea Lab
San Francisco Bay
Karina Nielsen, San Francisco State University, Estuary & Ocean Science Center
John Largier, University of California Davis, Coastal and Marine Sciences Institute
Santa Monica Bay
Tom Ford, Santa Monica Bay National Estuary Program
Alex Steele, Los Angeles County Sanitation District (Retired)
Tampa Bay
Kimberly K. Yates, U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center
Tillamook Bay Estuary
York Johnson, Water Quality Coordinator, Tillamook Estuaries Partnership
Cheryl Brown, U.S. EPA ORD, Pacific Ecological Systems Division
Stephen R. Pacella, U.S. EPA ORD, Pacific Ecological Systems Division
Reviewers:
Grace Robiou, U.S. EPA Office of Water
Nicholas Rosenau, U.S. EPA Office of Water
Bridget Cotti-Raush, 2019 Knauss Fellow
Nancy Laurson, U.S. EPA Office of Water
Alice Mayio, U.S. EPA Office of Water (retired)
Vince Bacalan, U.S. EPA Office of Water
Bill Fisher, U.S. EPA Office of Research and Development
Rochelle Labiosa, U.S. EPA Region 10
Patti Meeks, U.S. EPA Office of Research and Development
Any mention of trade names, products, or services does not imply an endorsement by the U.S. Government or EPA.
EPA does not endorse any commercial products, services, or enterprises.
The views expressed in this report are those of the authors and do not necessarily represent the views or policies of
the U.S. Environmental Protection Agency.

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Table of Contents
Executive Summary	1
Background on Coastal Acidification and its Impacts	4
1.1	Description of Ocean and Coastal Acidification	4
1.2	The Vulnerability of Nearshore and Estuarine Waters to Acidification	5
1.3	A New Approach to Monitoring Coastal Acidification at NEP sites	6
Estuary Characteristics, Monitoring Goals and Timeline	9
2.1	Estuary Characteristics	9
2.2	Goals of Monitoring	9
2.3	Monitoring Timeline	12
Monitoring Methods	13
3.1	Water Chemistry Sensors (pCO . pH)	13
3.2	Telemetry	15
3.3	Deployment Locations	15
3.4	Discrete Sampling	27
3.5	Data Collection, Processing and Storage Methods	30
3.6	Cost Information and Funding Sources	34
Deployment and Data Management Challenges and Lessons Learned	36
4.1	Deployment Challenges and Lessons Learned	36
4.2	Data Management Challenges and Lessons Learned	43
4.3	Data Interpretation Challenges and Lessons Learned	44
4.4	Data Quality Challenges and Lessons Learned	45
Monitoring Partnerships and Public Outreach	46
5.1	NEP Monitoring Partnerships	46
5.2	Partnership Challenges and Lessons Learned	48
5.3	Public Outreach Efforts	50
Preliminary Monitoring Results	52
Next Steps	67
References	71

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Executive Summary
Estuaries and coastal areas are highly vulnerable
to the impacts of acidification on shellfish, coral
reefs, fisheries, and the commercial and recreational
industries that they support. Yet, little is known about
the extent of this vulnerability and the estuary-specific
drivers that contribute to acidification, such as nutrient
enrichment from stormwater, agriculture and wastewater
discharges, upwelling of C02-rich seawater, elevated
atmospheric CO, from urban and agricultural activities,
benthic and marsh-driven processes, and alkalinity and
carbon content of freshwater flows. Comprehensive,
high resolution monitoring data are needed at varying
spatial and temporal scales to provide actionable
information tailored to each estuary. Because carbonate
chemistry in the coastal environment can be affected by
nutrient dynamics, understanding how nutrient inputs
exacerbate acidification impacts is essential for the
formulation of estuary-specific actions.
EPA supports coastal acidification monitoring and
research in various ways (Table 1). The purpose of this
report is to share EPA's approach to long-term coastal
acidification monitoring in which it initiated the use of
autonomous monitoring sensors for dissolved carbon
dioxide (pCO.) and pH deployed in situ in estuaries
across the country through EPA's National Estuary
Programs (NEP) and their partners. This approach
captures the high-resolution data that are needed to
understand variability associated with acidification
and ultimately to inform trends and mitigation and
adaptation strategies for these vulnerable systems.
This report details the plans and experiences of ten
NEPs geographically distributed around the U.S. coast
and their partners in conducting this monitoring over
the last four years (2015-2019). The report illustrates
the monitoring goals, deployment methods, data
analysis, costs, preliminary results, and the role of
partnerships in their successes. The preliminary results
have already improved our understanding of baseline
carbonate chemistry conditions in these estuaries,
the factors affecting spatial and temporal variability,
and the drivers responsible for changes in pC02 and
associated acidification. The sensors are successfully
capturing seasonal variability and finer temporal trends
that provide information on diel variability, physical
processes (e.g., weather, tides), and biological activity
which cannot be captured with discrete sampling alone.
The preliminary data indicate that there are regional
differences in the drivers of acidification, particularly the
Measuring Coastal Acidification Using In Situ Sensors
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influence of upwelling events vs. land-based freshwater
sources. Several of these NEPs have calculated
aragonite saturation state, an indicator of conditions
in which mollusk shells begin to dissolve and have
identified certain vulnerable conditions for shellfish and
other economically-important species in their estuaries.
Important lessons have been learned from these
deployments. Biofouling, which inhibits effective
sensor operation, was a significant challenge. Other
challenges were difficult weather conditions, such
as winter icing and hurricanes, and red tides that
prohibit dive operations. These situations result in the
temporary cessation of the sensor deployments and
consequently data gaps. Two NEPs avoided biofouling
and inhospitable environmental conditions by deploying
the instruments in weatherproof coolers with flow-
through systems. The ability to incorporate telemetry
to transmit real-time data was seen as a very valuable
asset to signal equipment failure or other reasons for
a lapse in data collection. To address several of the
challenges, these NEPs recommended purchasing
redundant sensors to minimize any gaps in data
collection but found it to be cost-prohibitive. They also
stressed the importance of collecting in situ data for
associated parameters so that acidification can be
interpreted in the context of inshore processes, such as
system hydrodynamics, mixing, and primary production.
This EPA report provides additional insights on the
challenges, lessons learned, and unique solutions
regarding the use of these autonomous sensors in
diverse estuarine environments.
EPA believes that sharing the methodologies and
lessons learned in this report will lead to information
sharing and technology transfer that will benefit the NEP
community and other coastal monitoring groups, such
as NOAA's 29 National Estuarine Research Reserves. In
addition, this report provides useful information to a wide
variety of stakeholders - from state legislators to shellfish
growers to concerned citizens - who are interested in
advancing the understanding of acidification drivers
in order to protect their vulnerable estuaries from the
impacts of acidification. The NEPs identified in this
report have already begun integrating their monitoring
results into actionable plans, such as their long-term
Comprehensive Conservation and Management
Plans (CCMPs) and State of the Bay reports, to inform
stakeholders and identify ways to address coastal
acidification vulnerabilities.
Over the long term, as these NEPs and other groups
continue this monitoring, the monitoring data will help
further characterize the vulnerability of these estuaries
to acidification, detect potential impacts of acidification
on locally important industries, and quantify the relative
contribution of specific pollution sources. The state of
the science of long-term coastal acidification monitoring,
including advancement of in situ autonomous pH and
pCO.., sensors, is rapidly evolving. The monitoring
community is encouraged to continue to share results
and lessons learned to inform applications of these data
to guide mitigation and adaption strategies.
Executive Summary

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Table 1. EPA's Coastal Acidification Activities
ACTIVITY
DESCRIPTION
Inter-Agency Working
Group on Ocean
Acidification
EPA is an active member of the Inter-Aaencv Workina Group on Ocean
Acidification dAG-OA) which develops and updates the Strateaic Plan for Federal
Research and Monitoring of Ocean Acidification, provides Reports to Congress,
and conducts other activities. The IAG-OA also spearheaded the creation of the
Ocean Acidification Information Exchanae in collaboration with the Northeastern
Regional Association for Coastal Ocean Observing Systems (NERACOOS) to
share resources, access up-to-date information, and interact across disciplines
and regions.
NEP Coastal Acidification
Monitoring
In 2015 and 2016, EPA funded coastal acidification monitoring equipment for nine
NEPs and their partners as identified in this report.

In 2018. EPA published Guidelines for Measurina Chanaes in Seawater pH and
Associated Carbonate Chemistrv in Coastal Environments of the Eastern United

States (Pimenta and Grear. 2018).

EPA Region 1 (New England) increased the technical capacity of citizen scientists
monitorina coastal acidification in the Northeast bv supportino Shell Dav (2019').

EPA funded the Ocean to Plate to Ocean pilot study in Casco Bay that tests the
impact of shell material deposition on pH and shellfish recruitment in tidal flats
and demonstrates the feasibility and value of a shell collection program in Maine.
EPA's National Coastal
Condition Assessment
(NCCA)
EPA added total alkalinity as a research parameter to the 2020 survey. These
measurements will provide a baseline understanding for coastal acidification
buffering capacity against the drivers of coastal acidification for 750 sites across
the contiguous U.S. and will improve models for predicting alkalinity from salinity
in under-sampled areas.
EPA's Office of Research
and Development (ORD)
Coastal Acidification
Research
ORD's Narragansett, Rl Laboratory Research Facility and Pacific Ecological
Systems Division in Newport, OR conduct monitoring and research on the
ecological impacts of coastal acidification. Research is also being conducted to
attribute coastal water quality impacts to local and global acidification drivers.
Executive Summary

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Background on Coastal
Acidification and Its Impacts
1.1
Description of Ocean and Coastal Acidification
The ocean is currently experiencing rapid rates of
acidification and carbonate ion reduction, which may
exceed changes of the past 300 million years (Honisch
et al., 2012). Globally, one-third of anthropogenic COft:
released into the atmosphere is being absorbed by the
ocean every year (NRC, 2010). When CO, dissolves in
seawater, it lowers the pH and reduces the availability
of carbonate ions, impairing the ability of marine
organisms to form calcified shells or skeletons and
impacting other fundamental physiological processes
such as respiration, photosynthesis, and reproduction.
These impacts alter food webs and negatively affect
economies dependent on services ranging from coral
reef tourism to shellfish harvesting and fisheries.
Since preindustrial times, the average ocean surface
water pH has fallen by approximately 0.1 units (30%)
globally, from approximately 8.21 to 8.10 (Royal Society,
2005). However, pH could decrease a further 0.3-0.4 pl-l
units globally by 2100 if atmospheric C02 concentrations
reach 800 pprn (Orr et al, 2005). Biological effects of
acidification are occurring now and could become
more severe. For example, pteropods, a pelagic sea
snail that is an important prey species for fish such as
salmon, cod, and mackerel, are especially vulnerable to
corrosive conditions. Mass mortality events in shellfish
hatcheries have also been linked to ocean acidification.
Coral reefs, which provide trillions of dollars in societal
services worldwide, are projected to experience
decreased net calcification, a process necessary to
maintain ecosystem function (Bushinsky et al, 2019).
Ocean acidification
seawater pH
2100 (projected)
increased acidity
higher concentration
of atmospheric C02
HsCOg
carbonic acid
late 1800s
reduced acidity
seawater pH
9
lower concentration
of atmospheric C02
CO2
carbon dioxide
carbon dioxide
H2CO
carbonic acid
fewer
carbonate ions
carbonate ions
H
free hydrogen ions
H
free hydrogen ions
bicarbonate
bicarbonate
abundant healthy corals
mollusks, and other
marine calcifiers
fewer, smaller
marine calcifiers
Encyclopedia Britannica, Inc.
Conceptual diagram comparing the state of carbonates in the oceans under the
lower-acid conditions of the late 1800s with the higher-acid conditions expected for
the year 2.100. Image: Encyclopaedia Britannica, Inc.
Measuring Coastal Acidification Using In Situ Sensors
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1.2
The Vulnerability of Nearshore and Estuarine Waters to Acidification
In estuarine and coastal areas, the causes, magnitudes,
and rates of acidification differ in complexity as
compared to the open ocean due to many natural and
anthropogenic processes. In the coastal environment,
in addition to atmospheric C02 inputs, acidification
could be locally amplified by a complex array of factors,
including: the alkalinity and carbon content of freshwater
flows; direct acid deposition; elevated atmospheric
CO, from urban and agricultural activities (Northcott
et al, 2019); and changes in coastal circulation and
upwelling of C02-rich seawater from the ocean. In
particular, direct nutrient enrichment from stormwater,
agriculture and wastewater discharges can contribute
to coastal acidification. Excess nutrients fuel algae
and phytoplankton growth. As the phytoplankton die
and decay, C02 is respired by microbes and the gas is
dissolved into seawater. As a result, local and regional
"hot spots" of increases in pCO, and declines in pH in
coastal areas can occur, which are likely to be magnified
when combined with other stressors in coastal ocean
(Kelly et al, 2011). In addition, many coastal organisms
have sensitive estuarine and nearshore life stages
that coincide with mid and late summer extremes in
dissolved oxygen, pH, and other characteristics of the
carbon system and are thus expected to be especially
vulnerable (Wallace et al, 2014). These complex
biochemical dynamics need further study to better
understand the relative contribution of these drivers to
help coastal communities mitigate or adapt to coastal
acidification.
emissions
Point source
Stormwater
v runoff
iU. I
Erosion
Fertiliier
Background on Coastal Acidification and its Impacts

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1.3
A New Approach to Monitoring Coastal A
On the national scale, several agencies conduct
ocean acidification monitoring. For example, NOAA's
Ocean Acidification Monitoring Program's monitoring
network includes repeat hydrographic surveys, ship-
based surface observations, and time series stations
(mooring and ship-based) in the open ocean waters
of the Atlantic, Pacific and Arctic, and the Gulf of
Mexico. The development of new long-term monitoring
systems is critical for filling the existing knowledge gaps
and advancing the current technology, especially in
highly vulnerable areas such as high-latitude regions,
upwelling regions, warm and cold-water coral reefs,
and in coastal regions and estuaries where less is
understood about the temporal and spatial variability of
acidification.
The carbonate chemistry of estuaries is controlled by
multiple co-occurring chemical, biological, and physical
processes operating at various rates (from sub-hourly to
inter-annual time scales). Because coastal environments
have greater pH variability than the open ocean, the
ability to detect real trends in coastal acidification and
distinguish these from background variability requires
high-quality, long term, high resolution monitoring. In
addition, continuous monitoring of multiple parameters
at a high temporal and spatial scale is vital in order to
distinguish the relative influence of the drivers of coastal
acidification, particularly nutrient-enhanced acidification.
There are a small number of sites capturing long-term,
decadal, coastal pH data useful for understanding
short-term and spatial variation in coastal acidification,
including NOAA's National Estuarine Research
Reserves. However, the tools and approaches that are
used are not consistent with those needed to detect
climate scale trends and changes associated with
anthropogenic changes in atmospheric C02. The use of
autonomous pC02 and pH sensors for high-resolution
monitoring in the estuarine environment is a new,
innovative approach that will complement the existing
long-term pH measurements to provide climate level
measurements. These types of autonomous sensors
dification at NEP sites
have been used extensively in the open ocean to
monitor ocean acidification, however, their deployment
in situ in nearshore and estuarine waters is new and
challenging due to rapid variation over large ranges
in salinity and chemical composition, accuracy issues
such as biofouling and sensor drift, and other factors
(Sastri et al., 2019). In 2018, EPA published "Guidelines
for Measuring Changes in Seawater pH and Associated
Carbonate Chemistry in Coastal Environments of the
Eastern United States" which includes a discussion
of these autonomous sensors (Pimenta and Grear,
2018). Typically, as part of quality control, in addition
to in situ measurement of pC02 and pH, discrete water
samples are collected by the monitoring programs to
be analyzed in the laboratory for total alkalinity (TA) and
dissolved inorganic carbon (DIC). Any two of the four
parameters (pH, pC02, DIC and TA) can be used to
measure aragonite state. Currently, pH and pC02 are
the two parameters that are routinely measured using
deployed sensors, but extensive research is currently
underway to develop the technology that will permit
development of sensors to measure DIC (e.g. at Woods
Hole Oceanographic Institution).
EPA and the National Estuary Program (NEP) play
an important role in understanding the impact of
coastal acidification on water quality and living
marine resources. The NEP is a place-based program
established by Section 320 of the Clean Water Act with
the mission to protect and restore the water quality and
ecological integrity of estuaries of national significance.
The 28 NEPs are located in coastal watersheds along
the Atlantic, Gulf, and Pacific coastlines, and in Puerto
Rico. Each NEP focuses on the restoration of a study
area that includes the estuary and a portion of the
surrounding watershed. The NEPs are administered in
a variety of institutional settings, including state and
local agencies, universities and individual nonprofit
organizations. Of the 28 NEPs, 19 have identified coastal
acidification as an emerging threat to their coastal
resources in their Comprehensive Conservation and
Background on Coastal Acidification and its Impacts

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Management Plans (CCMPs. 2003-2019), which contain
actions to address water quality and living resource
challenges and priorities (Figure 1). The CCMPs
are long-term plans developed through a unique,
consensus-based approach, and implemented with a
variety of local partners. Many of these NEPs highlight
the need for more data to improve understanding of
acidification trends, the causes of low pH in their study
areas, and effects of acidification on living resources.
They also describe the need for local monitoring and
research to develop acidification adaptation and
management strategies. For example, in estuaries in
which more acidic conditions are driven by upwelling
events, strategies could include alerts to shellfish
hatcheries warning of highly acidic conditions and
implementing aquaculture techniques to buffer hatchery
systems. In estuaries where acidic conditions are driven
by eutrophic conditions, nutrient management strategies
ranging from source reduction to seagrass restoration
can be used to reduce acidification in vulnerable areas.
Several NEPs link acidification to their nutrient action
plans as a potential outcome of nutrient enrichment. In
addition, 13 of the 28 NEPs have referenced the issue
of acidification in their State of the Bav reports and cite
the need for more monitoring data to establish baselines
and develop models to better understand long-term
trends in their estuaries (Figure 1).
The NEPs have demonstrated their leadership on this
issue by expanding the use of autonomous pC02 and
pH sensors deployed in situ in estuarine and nearshore
environments. Beginning in 2015, EPA funded nine NEPs
to purchase autonomous pC02 and pH sensors to better
characterize carbonate conditions and thus obtain a
better understanding of coastal acidification in their
respective estuaries (Figure 1). Mobile Bay also recently
purchased these sensors to conduct this monitoring.
EPA's Office of Research and Development (ORD)
Pacific Ecological Systems Division is also conducting
this monitoring in Tillamook Estuary. Over the past four
years, monitoring at eight1 of these ten NEPs has been
conducted through the collection of sub-hourly data
(pC02 and pH) and optimization of monitoring methods
and data analysis procedures. The monitoring at these
ten NEPs are the subject of this report. The Puget
Sound Partnership, primarily through the Washington
Department of Ecology, also conducts coastal
acidification monitoring using autonomous, in situ pH
and pC02 sensors and the regular collection of discrete
water samples. Although this data is not included in
this report, more information can be found here: https://
ecology. wa.gov/Water-Shorelines/Puaet-Sound/lssues-
problems/Acidification.
1 MassBays and Mobile Bay are developing their monitoring methods but have not yet deployed their sensors.
Background on Coastal Acidification and its Impacts

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(g1 —Casco Bay
2 Estuary
(t\a Partnership
\5/4 — Massachusetts
Bays NEP
Pudget Sound
Partnership —
Long Island-
Sound Study
5
r% 6
10O>ฎ9 — Barnegat Bay
) Partnership
26* .27
Tillamook —
Estuaries
Partnerships
San	
Francisco
Estuary
Program
Santa Monica — 23ฎ
Bay Restoration
Foundation
Mobile Bay NEP
Tampa Bay
Estuary Program
Coastal Bend Bays—-
and Estuaries Program
• NEP references acidification in
O NEP addresses acidification
~ NEP conducts acidification monitoring
latest State of the Bay report
in their CCMP
using autonomous pH and pC02 sensors
1	Casco Bay Estuary Partnership	10
2	Piscataqua Region Estuaries
Partnership	11
3	Buzzards Bay NEP	12
4	Massachusetts Bays NEP	13
5	Narragansett Bay Estuary	14
Program	15
6	Peconic Estuary Partnership	16
7	Long Island Sound Study	17
8	New York-New Jersey Harbor	^
Estuary Program
19
9	Barnegat Bay Partnership
Partnership for the Delaware
Estuary
Delaware Center for the Inland Bays
Maryland Coastal Bays Program
Albemarle-Pamlico NEP
Indian River Lagoon NEP
San Juan Bay Estuary Program
Coastal and Heartland NEP
Sarasota Bay Estuary Program
Tampa Bay Estuary Program
Mobile Bay NEP
Barataria-Terrebonne NEP
21	Galveston Bay Estuary Program
22	Coastal Bend Bays and Estuaries
Program
23	Santa Monica Bay Restoration
Foundation
24	Morro Bay NEP
25	San Francisco Estuary Partnership
26	Tillamook Estuaries Partnerships
27	Lower Columbia Estuary
Partnership
28	Puget Sound Partnership
Figure 1. National Estuary Programs Addressing Coastal Acidification
Background on Coastal Acidification and its Impacts

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Estuary Characteristics,
Monitoring Goals and Timeline
2.1
Estuary Characteristics
The ten NEPs, along with their partners, that are
conducting coastal acidification monitoring using the
continuous sensors include the following:
•	East Coast
ฆ	Casco Bay Estuary Partnership, ME
ฆ	Massachusetts Bay National Estuary Partnership,
MA (MassBays)
ฆ	Long Island Sound Study, NY & CT
ฆ	Barnegat Bay Partnership, NJ
•	Gulf of Mexico
ฆ	Tampa Bay Estuary Program, FL
ฆ	Mobile Bay National Estuary Program, AL
ฆ	Coastal Bend Bays and Estuaries Program, TX
•	West Coast
ฆ	San Francisco Bay Estuary Partnership, CA
ฆ	Santa Monica Bay National Estuary Program, CA
ฆ	EPA ORD/Tillamook Estuaries Partnership, OR
These ten NEPs vary in geographic location, size,
environmental stressors, coastal dynamics and
processes, and local economic interests. Santa Monica
Bay is especially unique among these estuaries as the
only deep, open coastal site as compared to the other
more shallow, enclosed estuaries.
•	Watershed Size: Small (663 mi2-Barnegat Bay) to
large (12,580 mi2-Coastal Bend Bays)
•	Land Use: Urbanized (Barnegat Bay) versus rural
and agricultural (Tillamook Estuary)
•	Watershed Population: 25,000 (Tillamook Estuary) to
9,000,000 (Long Island Sound)
•	Estuary Depth: Shallow (Tillamook Estuary,
San Francisco Bay) versus deep and open coast
(Santa Monica Bay)
•	Acidification Drivers: Freshwater inputs
(Coastal Bend Bays) versus ocean upwelling
(Santa Monica Bay)
2.2
Goals of Monitoring
The ten NEPs share many of the same coastal
acidification monitoring goals. These goals are centered
on understanding the existing conditions of carbonate
chemistry in the estuaries and how it is impacted by
terrestrial and oceanic inputs.
Common Goals:
•	Establish carbonate chemistry baseline data to
determine background conditions.
•	Better characterize the variability of carbonate
conditions (daily, seasonal, and annual fluctuations)
at a "continuous" time scale.
•	Improve the understanding of land-based inputs
(nutrient loading, freshwater flows) versus oceanic
influence (upwelling) on the carbonate chemistry and
oxygen dynamics.
•	Determine how carbonate chemistry patterns are
changing.
•	Determine the effect of coastal acidification on
plankton, shellfish and other species and the
potential economic impacts to the bays and
estuaries.
•	Understand the relationship of alkalinity and salinity
and inform our understanding of carbon dynamics.
•	Build confidence in the performance of the sensors.
Based on their defining physical, hydrologic and living
resource characteristics, these NEPs also have regional
and estuary-specific monitoring goals, which are
presented below.
East Coast Regional Goals:
The four NEPs in the East Coast are characterized by
cool waters, with some coastal upwelling. Two of the
NEPs (Casco Bay and MassBays) are characterized
by large tidal influence, ranging up to 9-14 ft. These
NEPs have numerous priorities, including protecting and
restoring shellfish habitat. Their goals are to understand
the impact of coastal acidification on shellfish resources/
industry in the estuaries, as well as shellfish restoration
and aquaculture efforts that are occurring in the area.
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•	Casco Bay: The Maine legislature created a
bipartisan ocean acidification panel. They produced
the report "Commission to Study the Effects of
Coastal and Ocean Acidification on Commercially
Harvested and Grown Species" and described
acidification as a major stressor for lobster and
clam fisheries in Maine and the importance of
understanding calcification to protect the aquaculture
industry. This monitoring will help understand the
impact of coastal acidification on Maine's shellfish
resources and other living resources.
•	MassBays: The overall objective is to identify
coastal acidification conditions and to determine
the potential impacts of acidification on aquaculture
practices of the Eastern oyster, Crassostrea virginica
that would serve to inform the shellfish industry
and other stakeholders. With the convening of the
Massachusetts Ocean Acidification Commission
(2018) by the Massachusetts legislature and the
establishment of the Massachusetts Shellfish
Initiative, this project will provide baseline information
for informed decision-making.
•	Barnegat Bay: The objective is to determine if
coastal acidification is negatively impacting the
shellfish restoration and aquaculture efforts that
are happening in the area. Hard clams (Mercenaria
mercenaria) are the subject of both wild harvest and
aquaculture, while eastern oysters are an expanding
aquaculture product in the estuary. Both clams and
oysters are the focus of restoration efforts due to
reduced wild populations compared to historic levels.
•	Long Island Sound: Understand the why, how,
and what controls the distribution of oxygen and
the extent and duration of hypoxia within the
Sound, which occurs annually in the summer and
the potential overlap of acidification. They use
buoys to observe daily fluctuations and long-term
improvements in hypoxia due to reductions in
nutrients.
•	Barnegat Bay: Understand the interaction of
multiple acidification enhancers in the Bay including
eutrophication, localized seasonal coastal upwelling
and extremely low pH freshwater sources.
Gulf of Mexico Regional Goals:
The three NEPs in the Gulf of Mexico region are in a
transition zone between warm-temperate and tropical
biogeographic provinces, and are characterized by
warm, productive waters. These NEPs described their
goals as the following.
•	Tampa Bay:
ฆ	Assess the contribution of seagrass, mangrove
forest and salt marsh habitats to sequestration
of C02 as blue carbon, and the role of seagrass
in protecting Tampa Bay's marine species from
harmful effects of climate change and coastal and
ocean acidification.
ฆ	Understand the seasonal and diurnal variations in
carbonate chemistry in the bay, and the influence
of Gulf of Mexico waters.
•	Mobile Bay:
ฆ	Understand trends and variability in carbonate
chemistry related to river discharge and mixing
with Gulf of Mexico waters.
ฆ	Develop predictive models of acidification and
hypoxia and impacts to economically important
shellfish and finfish populations.
•	Coastal Bend Bays: Examine the role of freshwater
inflow from rivers on the recently observed trends in
the carbonate system changes in Aransas Bay.
Estuary Characteristics, Monitoring Goals and Timeline

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West Coast Regional Goals:
The NEPs in the West Coast region are characterized
as having cooler, deeper waters with prominent coastal
upwelling. These NEPs described their goals as:
•	Santa Monica Bay:
ฆ	Observe the impact of deep, colder water off the
California coast on acidification and hypoxia.
Capture the signal of upwelling events at 60m
depth and determine whether the narrowness of
the continental shelf plays a role.
ฆ	Establish a baseline dataset to assess and track
ocean acidification and hypoxia in the Bay,
which receives significant nutrient loading from
anthropogenic activities.
ฆ	Develop expertise in operation and maintenance
of the next generation of acidification monitoring
sensors.
ฆ	Provide data for validation of model simulations,
and to inform restoration efforts by Santa Monica
Bay National Estuary Program.
ฆ	Provide final quality assurance (QA)/quality control
(QC) data to the West Coast-wide California
Current Acidification Network (C-CAN) that will be
served publicly through the U.S. Integrated Ocean
Observing System (IOOS) network.
•	San Francisco:
ฆ	Enhance understanding of how climate change
and watershed modifications and activities
contribute to coastal acidification.
ฆ	Detect low-pH waters intruding from the ocean,
especially during upwelling events in the spring
and summer, in contrast to freshwater inflow
events.
ฆ	Understand "natural cycles" within the Bay.
Agricultural runoff leads to eutrophication, but the
bay is not usually in a eutrophic state (no dense
algal blooms).
ฆ	Understand the potential role of submerged
aquatic vegetation (eelgrass and algal
macrophytes) and wetlands in modifying
carbonate chemistry of shallow water habitats.
ฆ	Understand the influence of coastal acidification
on restoration and health of the native shellfish, the
Olympia oyster and nursery habitat for Dungeness
crab fishery.
ฆ	Understand the potential influence of coastal
acidification on migrating salmonid and other
endangered fish species in the estuary.
• Tillamook Estuaries:
ฆ	In 2017, the Oregon Senate created the Oregon
Coordinating Council on Ocean Acidification
and Hypoxia (OAH Council) to provide
recommendations and guidance for the State on
how to respond to this issue. The OAH Council
developed a six-year Ocean Acidification
& Hypoxia Plan in 2019 in recognition that
acidification and hypoxia events are undermining
the state's rich ocean ecosystem food web.
This monitoring will help to determine the role of
watershed land use and eutrophication drivers
versus coastal ocean conditions on occurrence of
estuarine acidification and hypoxia.
ฆ	Identify sources of nutrients, bacteria, and organic
material using stable isotopes and microbial
source tracking upstream and downstream of
areas with high human land use modification.
ฆ	Develop models to predict the impacts of climate
change and watershed activities on water quality.
Estuary Characteristics, Monitoring Goals and Timeline

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2.3
Monitoring Timeline
Monitoring of coastal acidification by the NEPs identified
in this report began on the East Coast in 2015 in Casco
Bay and in many places continues today (Figure
2). Over the past four years, these NEPs have been
collecting hourly and sub-hourly coastal acidification
data (pC02 and pH). MassBays and Mobile Bay plan to
deploy equipment in 2020. Coastal Bend Bays' research
pier was destroyed in 2017 and the sensors could no
longer be deployed.
2015
2016
2017
2018
2019
2020
Casco Bay
East Coast
PH
PC02
Long Island Sound
4/15-1/16
4/15-1/16
6/16-3/17
6/16-3/17
ฆ
6/17-2/19
ฆ


| 4/17 - Present
12/16-2/17
PH



4/17-12/18 4/18-12/18
5/19 -Present I



I
PC02



4/17-12/18 4/18-12/18
5/19 -Present 1

12/16-2/17
I I
I
Barnegat Bay






11/16
-1/17
6/17-8/17 12/17 -1/8

PH



- 1





PC02



7/19 - Present 1

11/16
-1/17
6/17-8/17 12/17-1/8

Gulf of Mexico
Tampa Bay
pH/pC02
Coastal Bend Bays
pH/pC02
Santa Monica Bay
12/17 - Present
I 11/16-8/17 I
West Coast
PH
PC02
San Francisco Bay
11/16-9/17
7/16-7/17
1/18-1/19
1/18-1/19
pH/pC02
Tillamook Bay
3/20 - 10/20
pH/pC02- EPAORD
pC02-Tillamook Estuaries Partnership
8/17 - Present
7/19 - Present
Figure 2. Timeline of pH and pCO Autonomous Sensor Deployments of eight NEPs.
Estuary Characteristics, Monitoring Goals and Timeline

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Monitoring Methods
3.1
Water Chemistry Sensors (pC02, pH)
Two of the following four chemical parameters are
needed to describe the seawater carbonate system
-pC02, pH, dissolved inorganic carbon (DIC) and
alkalinity—along with contemporaneous measures of
temperature and salinity. To record pH and pC02 data,
autonomous sensors are being used in the ten NEPs
(Table 2). Table 3 provides the specifications for these
sensors including the accuracy, precision, resolution,
and range. For measurement of pH, five of the NEPs
use the Satlantic SeaFET and five use the SeapHOx.
The SeaFET pH sensor is an ion-sensitive field effect
transistor (ISFET), which is shown to be more precise
and stable over time and more durable compared to pH
sensors that use a glass electrode. The pH range for
the SeaFET is 6.5 to 9.0 pH. The SeapFlOX integrates a
SeaFET pH sensor with additional Seabird sensors that
measure temperature, salinity, and dissolved oxygen
(DO). The SeapFlOX also includes an internal water
pump and anti-fouling technology. Both the SeaFET and
SeapFlOX have internal battery power and data logging
capabilities. MassBays' acidification system includes a
Sunburst Sensors SAMI-pH, which measures pH using
a colorimetric reagent method. The pH range for the
SAMI-pFI is 7 to 9. All pH data reported by the NEPs are
on the "total" hydrogen ion concentration scale (pHT).
For measurement of pCO.-,, six of the NEPs use the
Sunburst Submersed Automated Monitoring Instrument
(SAMI-C02) and the remaining NEPs use a Sunburst
Shipboard Underway pC02 Environmental Recorder
(SuperC02), Pro-Oceanus C02-Pro, or Moored
Autonomous pC02 (MAPC02). The Sunburst SAMI-C02
uses a colorimetric reagent method to measure the
partial pressure of C02 from 200 to 600 patm. The
Sunburst Sensors SUPER-C02, Pro-Oceanus C02-Pro,
and Moored Autonomous pC02 (MAPC02) all measure
pC02 using an infrared C02 detector. Flowever, the
Sunburst Sensors SUPER-C02 is designed for shipboard
analysis (not in situ deployment) and uses a Windows-
based computer for analysis control and data collection
and display.
Additional parameters allow for the analysis and
identification of the drivers of estuarine carbonate
chemistry. All ten of the NEPs are collecting in situ
measurements of temperature and salinity. Eight of the
NEPs are also measuring DO, and six are collecting
in situ chlorophyll a data (also measured as in situ
fluorescence and photosynthetically active radiation
(PAR)). One NEP, San Francisco Bay is also measuring
atmospheric C02. These supporting data are measured
using a variety of Seabird, YSI, Aanderaa and other
instruments (Table 2).
The magnitude and timing of changes in temperature,
pC02 and pH allows for a determination of the diurnal
and seasonal control. Salinity data provides information
about the influence of tides and to distinguish between
watershed and oceanic influences. Temperature data
are used in conjunction with pC02, salinity, and pH
data to assess, among other things, the timing and
magnitude of oceanic upwelling and its associated
effects on estuarine water chemistry. Dissolved oxygen
paired with pC02 can provide information about
biological activity. Measurements of chlorophyll a
and in situ fluorescence and photosynthetically
active radiation (PAR) can provide an estimate of the
abundance of phytoplankton which is an indicator of
the eutrophic condition of the estuary which can inform
an understanding of the impact of nutrient enrichment
on the coastal carbonate chemistry. Turbidity provides
information about the amount of suspended sediment in
water which can block light to aquatic plants and carry
pathogens. Coupling the monitoring information with
runoff or other watershed data allows for assessment of
oceanic versus watershed controls and may allow for
greater insight into local versus regional drivers.
This monitoring data can also inform calculations of the
aragonite saturation state of water. Aragonite saturation
state is commonly used to track ocean and coastal
acidification because it is a measure of carbonate ion
concentration. As aragonite saturation state decreases,
it is more difficult for organisms to build and maintain
calcified structures. Calculating aragonite saturation
requires that, in addition to temperature and salinity,
at least two of the carbonate parameters (pC02, total
alkalinity, DIC, pH) be known. However, pCO, and
Measuring Coastal Acidification Using In Situ Sensors
in the National Estuary Program

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pH data from the sensors are not an ideal set of input
parameters for calculating aragonite saturation (i.e.
using the C02SYS software package) because they
carry the most uncertainty (Orr et al, 2018). Discrete
samples analyzed for dissolved inorganic carbon (DIC)
and/or alkalinity can be used in conjunction with pH and/
or pC02 to calculate aragonite saturation states and act
as validation data for the in-situ sensors, but many of
these NEPs do not yet have the required discrete data
available to make these calculations and therefore do
not yet report time series of calcium carbonate
saturation states.
Table 2. Continuous Monitoring Sensors for pH and pC02 and other parameters.
NEP
pH SENSOR
pC02 SENSOR
OTHER SENSOR
MEASUREMENTS1
Casco Bay
Sea-Bird SeaFET
Sunburst SAMI-C02
Aanderaa Oxygen Optode (DO)
Seabird CTD (T, S)
MassBays
Sunburst AFT pH
Sunburst SUPER-C02
Turner Designs Cyclops C7
(Turbidity, CDOM)
Seabird SB45 (T, S)
YSI (chlorophyll a, DO)
Long Island
Sound
Sea-Bird SeaFET
Sunburst SAMI-C02
Sea-Bird Hydrocat EP X2 (DO)
YSI (T, S, Turbidity, chlorophyll a)
Barnegat Bay
Sea-Bird SeaFET
Pro-Oceanus C02 Pro-CV
YSI Exo2 Sonde
(T, S, DO, Turbidity)
Tampa Bay Sea-Bird SeapHOx	Pro-Oceanus C02-Pro	SeapHOx (T, S, DO)
Wetlabs EcoPAR
Mobile Bay Sea-Bird SeapHOx	Sunburst SAMI-C02	YSI (T, S, DO, chlorophyll a)
Coastal Bend Sea-Bird SeaFET	Sunburst SAMI-C02	YSI (T, S)
Bays
Santa Monica Sea-Bird SeapHOx	Sunburst SAMI-C02	Sea-Bird SeapHOx (T, S, DO)
Bay
San Francisco Sea-Bird SeaFET	Moored Autonomous	Sea-Bird SeaFET & CTD
Estuary	(surface)	pC02 (MAPC02)	(T, S, DO, chlorophyll a)
Sea-Bird SeapHOx	Sea-Bird SeapHOX (T, S, DO)
(deep)
Tillamook	Sea-Bird SeaFET &	Sunburst SAMI-CO,	YSI (T, S, DO, chlorophyll a)
Estuary	Sea-Bird SeapHOx
1 Temperature (T), Salinity (S), Dissolved oxygen (DO), Colored Dissolved Organic Matter (CDOM)
Monitoring Methods

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Table 3. Sensor Specifications.
INSTRUMENT
PARAMETER
ACCURACY
PRECISION
RESOLUTION
RANGE
SunBurst SAMI-CCX
pC02
+/- 3 patrn
ฑ 0.5-1 patrn

150-7008
Pro-Oceanus C02-
ProCV
pC02
ฑ0.5% of
meas. val.
0.01 ppm

0-10,000
MAPC02b
pC02
+/- 3 patrn
0.7 ppm

0-10,000

pH
ฑ 0.05

ฑ 0.004
6.5-9
Sea-Bird SeapHOx
DO
ฑ0.1 mg l_1

0.2 pmol kg-1
120% of
surf. sat.

Temp
ฑ 0.002 ฐCC
ฑ 0.01 ฐCd

0.0001 ฐC
-5 to 45 ฐC
Satlantic SeaFET
pH
ฑ 0.02
ฑ 0.004

6.5-9
Aanderaa Oxygen
Optode
DO
<8 |jM

<0.1 |JM
0-1,000 |JM
a Instrument can be calibrated for extended ranges
b LiCOr LI-820 C02 gas analyzer (Sutton et al., 201)
Temperature range: -5 to 35 ฐC
,:l Temperature range: 35 to 45 ฐC
3.2
Telemetry
Six of the ten NEPs have coastal acidification systems
with wireless telemetry capability, which automatically
transmits the sensor data via a cellular system to a
land-based computer server that receives and stores
the data. The advantage of a telemetry system is the
real-time access to the data, which eliminates the need
to retrieve the sensor and download data. Telemetry also
allows the timely review of the data to identify potential
sensor malfunctions or issues while they are still
deployed. The use of data telemetry requires power to
run both the data logger and the telemetry system. Solar
panels and rechargeable batteries or landside electrical
current can be used to power the data telemetry
systems.
The four NEPs without telemetry (Casco Bay, Coastal
Bend Bays, Santa Monica Bay, and Tillamook Estuary)
are currently monitoring at locations that lack the
infrastructure necessary for cellular telemetry; however,
some of these NEPs hope to incorporate telemetry into
their systems in the future. Deployments without data
telemetry are retrieved manually on a regular basis,
and the data are downloaded directly from the sensors
or data logger. Data download usually coincides with
retrieval for sensor maintenance and service.
Monitoring Methods

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In 2015, Tampa Bay initiated a pilot study
to examine the potential role of seagrass
recovery in buffering Tampa Bay from ocean
acidification. Discrete and autonomous
water chemistry measurements were
collected and used to calculate carbon
speciation, pC02, and the saturation state
of aragonite. The spatial and temporal
heterogeneity and the water flow effects
observed in Upper and Lower Tampa Bay
informed the selection of the location and
appropriate sampling times and constraints
for the coastal acidification monitoring.
3.3
Deployment Locations
The deployment locations for the coastal acidification
monitoring equipment vary from fixed, land- based
structures (such as docks, piers, and pilings) to water-
based buoys and moorings. The following factors were
considered when determining on the location of the
deployments:
•	Accessibility of the site (legal access, secure
location, accessible from shore or by boat).
•	Availability of historic or present data monitoring
efforts at that location, which may be used to
augment the NEP's data collection effort or to
hindcast past pC02 levels using historically
available data.
•	Existing piers, moorings or buoys from which to
deploy instrumentation. This can result in significant
cost savings (Long Island Sound, MassBays,
Tampa Bay, Mobile Bay, Santa Monica Bay,
Tillamook Estuary)
•	Presence of point source, non-point source, or deep-
water upwelling inputs to study the influence of these
sources on coastal acidification (Tillamook Estuary).
• Hydrodynamics within the estuary:
ฆ	Freshwater versus ocean signals
(Tillamook Estuary)
ฆ	Capture bay-wide mixing in a major inter-island
tidal channel between the inner and outer bay
(Casco Bay)
ฆ	Shallow water eutrophic versus deeper water
aphotic contributions
(Santa Monica Bay, San Francisco Estuary).

Mooring (Diver connects
SeapHOx sensor to pCOJ
Credit: Sanitation Districts of
Los Angeles County
•	Presence of submerged aquatic vegetation, which
may help mitigate acidification effects
(Tampa Bay, Tillamook Estuary)
•	Presence of resources that could be negatively
impacted by acidification (shellfishing areas,
aquaculture, or shellfish restoration areas)
(MassBays, Barnegat Bay, Mobile Bay, San
Francisco Estuary, Tillamook Estuary)
Buoy (Long Island Sound
ARTG Buoy)
Cooler (Coastal Bend Bays)
Monitoring Methods

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CASCO BAY ESTUARY PARTNERSHIP
The Casco Bay acidification instrument array is located at a pier at Southern Maine Community College in South
Portland, The pier, which is over two-hundred feet long, is located in the Portland Channel, an important southern
outlet of Casco Bay, and near outlets of the Fore and Presumpscot Rivers in a relatively urban area of Casco Bay.
This location was selected because it is nearshore, accessible, and has historic nutrient data collected by the
Friends of Casco Bay.
The sensors are housed in a cage that is attached via a davit within a secure box at the pier in about 1 to 5
meters of water (depending on tide). The cage rests on the bottom, and the sensors are about 0.5 meter off the
bottom and always submerged. The metal frame with the instrument array is lowered through a trap door in the
pier. A hoist system and crank are used to raise the frame up for servicing.
Casco Bay instrument array	Lowering instrument array through door in Southern Maine
Community College pier, Portland Channel, ME
Monitoring Methods

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MASSBAYS
MassBays' instrument array in cooler	Sensor deployment, town pier in Duxbury Bay, MA
In spring 2020 MassBays is planning to deploy a flow-through pumped system that incorporates pH and pCUL
temperature, salinity and CDOM. The system will be mounted on a fixed pier in Duxbury Harbor, an estuarine
ernbayrnent where extensive oyster aquaculture takes place. Designed and constructed by the Center for
Coastal Environmental Sensing Networks (CESN) at UMass Boston, the system is built specifically to collect data
year-round as it will be minimally impacted by biofouling. Initial lab tests suggest pCO. sensor is consistent with
calibration gases. The sampling chamber has been modified to reduce interference from bubbles. The pumping
system with mounting pole, float, and internal plumbing has been designed and constructed to minimize
bubbles. The mounting pole was deployed experimentally in early 2019 and has survived the winter (with 7 days
of below-12ฐC temperatures) with minor warping resulting from sea ice.
! ••ฆA.i,-
FLOW STRAINER
COjREFERENCEll
CO, REFERENCE 21
CO, REFERENCE 3
REFERENCE 4
A \
Schematic diagram of the system being deployed in
Duxbury Harbor (CESN, UMass Boston)
Mounting pole at Duxbury Harbor Town Pier for pumping
seawater to the coastal acidification monitoring system
Monitoring Methods

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LONG ISLAND SOUND
Long Island Sound is using an existing series of Long Island Sound Integrated Coastal Observing System
(LISICOS) buoys to measure coastal acidification. The buoy locations were chosen to observe daily fluctuations
and the expectation to observe long-term improvement associated with nutrient reduction in the sound. The
Western Long Island Sound (WLIS) buoy is the main buoy (south of Greenwich. Connecticut) and has pC02 and
pH sensors at the bottom depth (approximately 70 feet deep). The ARTG buoy, 13.6 nm east of the WLIS Buoy, is
located at the edge of the hypoxia zone and has a pH sensor at the bottom depth (79 feet). If changes to hypoxia
were to occur over time due to management practices, they would be observed first at the ARTG buoy. These
buoys also collect DO, temperature, salinity, and current data. Sensors for meteorological (wind, air temperature,
pressure) are also mounted to the buoys.
Sunburst SAMI pCO:
Satlantic SeaFET pH
Long Island Sound instrument array
fWfBWt
WLIS buoy, south of Greenwich, CT
Monitoring Methods

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BARNEGAT BAY
Barnegat Bay maintains three continuous water quality monitoring stations in the Barnegat Bay-Little Egg
Harbor estuary. The northern two stations have been operating for over 10 years, while the southernmost station
was developed in 2016 specifically as a coastal acidification monitoring station. The BB-LEH estuary system
experiences several local amplifiers for acidification, which makes it ideal for monitoring carbonate chemistry.
There is an upwelling center off Little Egg Inlet, and Little Egg Harbor is also fed by low pH and alkalinity water.
Upper Barnegat Bay, meanwhile, is highly eutrophic. Finally, there are a number of shellfish aquaculture and
restoration projects going on throughout the watershed, in addition to the historic hard clam fishery.
The coastal acidification deployment is located on a piling at Morrison's Marina in Beach Haven, New Jersey.
The deployment is powered by a rechargeable 12-volt battery and solar panel. In the original build, the three
instruments were separated, with the SeaFET deployed vertically in its own tube, and the CO.Pro CV mounted
horizontally with the Sea-bird pump. After deploying it for some time with that layout and speaking with the
technical staff at Satlantic and Pro Oceanus, the devices were collocated together in a horizontal layout. The
Seabird pump now pushes the water through the SeaFET and then the C02Pro-CV, The YSI EX02 data sonde is
deployed in a vertical tube.
Barnegat Bay instrument array
Pilling with solar panel at Morrison's Marina,
Beach Haven, NJ
Monitoring Methods

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TAMPA BAY
Tampa Bay currently has two deployments. The Tampa Bay Ocean Carbon System (OCSv2) is deployed in mid -
water column (2.5 rn depth) on an existing University of South Florida (USF) piling (Middle Tampa Bay Physical
Oceanographic Real-Time System (PORTS) station), in collaboration with Dr. Mark Luther, USF. This system is
powered by a solar panel with rechargeable battery. The USF station provides meteorological parameters and is
also located near a National Oceanic and Atmospheric Administration (NOAA)/USF PORTS currents/tide station.
This location provides pre-existing infrastructure for cost savings to the NEP and is within a mixing area of the
bay, which will help determine the net impact of acidification on Tampa Bay.
A new array (OCSv3) was deployed in the Gulf of Mexico, 60 miles offshore from Tampa Bay, on October 25,
2018. The OCSv3 is a surface mount system on the existing USF Coastal Ocean Monitoring and Prediction
System (COMPS) C12 buoy in collaboration with Dr. Robert Weisberg. The acidification sensors were integrated
into the existing buoy using custom brackets and were programmed to measure and telemeter hourly data.
OCSv2 on USF piling, Middle Tampa Bay station	OCSv3 buoy, 60 miles offshore, Gulf of Mexico
Monitoring Methods

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MOBILE BAY
The Mobile Bay instruments will be deployed in 2020 at the Middle Bay Lighthouse (30ฐ 26.2 N, 88ฐ 00.7 W) at
a depth of approximately 4 m, which is about 1 in above the bottom. This site has been continuously monitored
for T, S, and DO since 2005 as part of the Alabama Real-time Coastal Observing System (ARCOS), which is
maintained by the Dauphin Island Sea Lab (https://arcos.disl.org). Waves and currents have also been monitored
at this site since 2012. Geographically, the site is in the middle of the Bay and is broadly representative of the
river influenced and highly productive Mobile Bay.
Prichal
Mobile
Daphne
Theodore
Fairhope
Bayou
La Batre
Daupfyn^^
Island Y
9
Gulf Shores
Alabama's Real-Time Coastal Observing System	Middle Bay Light Station in the center of Mobile Bay
(ARCOS) stations
Monitoring Methods

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COASTAL BEND BAYS
The Coastal Bend Bays deployment was located at the research pier of the University of Texas Marine Science
Institute, in the Port Aransas Ship Channel. In 2017, the pier was destroyed by a post Hurricane Harvey accident.
The ship channel (i.e., Aransas Pass tidal inlet), connects estuarine water with water in the northwestern Gulf of
Mexico. The 300-ft pier had a 1200 ft2 lab at its base and a 150 ft4 instrument room on the end (Hu et al., 2018).
The terminus of the pier and instrument room housed a weather station, tide gauge, current meter, and sensors
for water temperature and salinity. Gauges and sensors were all located at approximately 5 m underwater. The
Mission Aransas National Estuarine Research Reserve (MANERR) maintained the salinity and temperature
sensors, and data were being recorded every 15 minutes. The SAMI CO.. and Seal 11 pH sensors were housed
inside a 100-quart cooler, with surface water pumped directly from the ship channel (at approximately 3 ft depth
below the surface) into the cooler housing the sensors. Sensor measurements were made on the hour, after
20 minutes of pumping fresh seawater into the cooler prior to the measurement. The YSI sonde was deployed
directly into the ship channel at 3 ft depth. Coastal Bend Bays hopes that the research pier will be rebuilt, and the
sensors redeployed; however, they are also seeking to deploy at another site in productive waters.
Coastal Bend Bays cooler system housing sensors
University of Texas Marine Science Institute Research pier,
Port Aransas Ship Channel
Monitoring Methods

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SANTA MONICA BAY
Santa Monica Bay's instrument package consists of a Sunburst SAMI-pCCX and a Sea-Bird SeapHOx in a
custom-built frame. During Year 1, the sensors were suspended at 50 ft below the water surface at an existing
thermistor string mooring located offshore of Palos Verdes Point, where the water depth is approximately 75 ft.
This location was chosen to characterize the ocean acidification and hypoxia (OAH) in shallower water within
the surface mixed layer, and within a few hundred meters of established kelp beds. The depth and location of
the sensors were expected to minimize effects from point discharges to Santa Monica Bay. During the Year 2
deployment, the same sensor array was relocated on a new mooring further south near the outer edge of the
Palos Verdes shelf, where the water depth is 230 ft. The sensors were deployed at a depth of 197 ft. The location
for the second deployment was chosen to characterize the deeper water and to determine if the signals are
different than those picked up during the deployment in shallower waters, particularly during strong upwelling
events. Because both mooring locations were located near existing Sanitation Districts of Los Angeles County
water quality stations quarterly CTD casts were collected for comparison.
Santa Monica Bay instruments with custom cage
-1 m above instrumentation :; C instrumentation support buoys
Q
3-?m above bottom
Instrumentation package
~2m t ) Recovery float on release
V
Acoustic release
Anchor (~400 lbs) with coiled recovery line
Instrument deployment mooring diagram, deployed offshore
of the Palos Verdes Point (Year 1) and the outer edge of the
Palos Verdes shelf (Year 2)
Monitoring Methods

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SAN FRANCISCO ESTUARY
San Francisco Estuary has two deployments located in Central San Francisco Estuary, in the deep channel
that runs close to shore on the eastern side of the Tiburon peninsula. The monitoring location is within a tidal
excursion of the mouth of the bay, at the interface between Central Bay (outer embayment) and San Pablo Bay
(North Bay). There is a high range of salinity at this location (at low tide, there is an estuarine water signal and at
high tide there is an ocean water signal).
The first deployment is a surface deployment called the Bay Ocean Buoy (BOB), which consists of a MARCO ,
buoy with conductivity, temperature, and depth (CTD) and SeaFET sensors. The second is a deep-water
mooring at the 60 ft isobath with a SeapHOX located just above the bottom and is called the Marine Acidification
Research Inquiry (MARI).
San Francisco Estuary - BOB
MARI, deep-water mooring in Central Bay
Monitoring Methods

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TILLAMOOK ESTUARY
Tillamook's initial deployment by EPA ORD Pacific Ecological System Division is a fixed deployment at a dock at
the Port of Garibaldi, which is a commercial fish offloading location. This location is near the mouth of the estuary
as well as a wastewater treatment outfall. During periods of high river discharge, there is salinity stratification (and
temperature to a lesser extent). The sensor array is mounted underneath the dock, which protects the equipment
from floating debris and collisions with boats. The sensor array consists of one Satlantic SeaFET or SeapHOx
pH sensor (swapped during periods of calibration/maintenance), one Sunburst SAMI CO:: sensor, and one YSI
6000 series or EXO sonde. The array is accessed by boat and a pully system is used to raise the instruments for
retrieval and maintenance. The instruments are deployed approximately 1 meter above the bottom, and at an
average depth of 3.8 m.
Tillamook Estuaries Partnership expanded the project to include an additional station located adjacent to oyster
operations in the middle of the Tillamook Bay. A SeaFET and YSI EXO data sonde are contained in PVC pipes
mounted to a weighted 1 m by 1 m stainless steel basket. The basket is marked with a buoy and retrieved
for equipment maintenance and exchange. The mooring holds the instruments 0.3 m above the bottom at an
average depth of 2.5 m.
Tillamook Estuary's instrument array
Location of dock at Port of Garibaldi and nearby site of outfall
(Yellow dot - EPA ORD deployment site; Red dot - Tillamook
Estuaries Partnership deployment site)
Wa&tcvr.itcr
Treatment
Outfall
Monitoring Methods

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3.4
Discrete Sampling
In addition to the continuous, in situ sensor
measurements, discrete water samples are collected
by the ten NEPs to validate the sensor measurements
and to provide additional analytical data necessary
to characterize the water chemistry and to calculate
aragonite and calcite saturation. These NEPs most
often collect and analyze discrete samples for pi I,
dissolved inorganic carbon (DIC), and total alkalinity
.(TAJ, The frequency of discrete sample collection
ranges from weekly to quarterly and is often timed to
coincide with sensor cleaning, other maintenance, and
downloading the data. Most of the discrete sample
collection is conducted by these NEPs, their partner
staff or academic researchers. MassBays plans to use
trained citizen scientists to collect discrete samples on a
biweekly basis. In addition, a YSI sonde will be used to
measure turbidity, DO and chlorophyll a.
Some of these NEPs also use discrete or in situ
measurements collected by other research programs
to cross-calibrate their sensor data. For example, Santa
Monica Bay uses Conductivity, Temperature and Depth
(CTD) profile data, collected quarterly by Los Angeles
County Sanitation District (LACSD) at nearby stations,
San Francisco Estuary Sampling
Event
to evaluate the comparability between those CTD
measurements and the acidification mooring sensors.
Long Island Sound cross-calibrates its temperature,
salinity, pi I. and DO measurements with Connecticut
Department of Energy and Environmental Protection
ship surveys, which complement Long Island Sound's
acidification program.
A description of the discrete sampling programs for
each of the ten NEPs conducting coastal acidification
monitoring is provided below.
To be able to analyze discrete water samples and reduce turn-around time for sample results,
US EPA ORD procured a carbonate chemistry analyzer built by Burke Hales at Oregon State
University The system measures pC02 and DIC and can operate in both flow-through mode
and be used to collect discrete samples, Discrete water samples from Tillamook Estuary are
being analyzed using this instrumentation.
Monitoring Methods

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DISCRETE SAMPLING
CASCO BAY
Bottle samples are collected every four to six weeks for laboratory analyses for TA, DIC, and pH and used to
back-calculate estimated pH and pC02, and aragonite and calcite saturation. Sample collection coincides with
downloading the data and cleaning the sensors.
MASSBAYS
A program of biweekly discrete samples will be conducted. Citizen scientists will be trained to collect the
samples. The samples will be delivered to EPA's laboratory (Atlantic Coastal Environmental Sciences Division)
in Narragansett, R.I. and analyzed for total alkalinity and DIC. The Center for Coastal Environmental Sensing
Networks (CESN) at UMass Boston is currently collecting monthly discrete samples from Duxbury Harbor
to collect background data. This initial preliminary survey demonstrated that salinity was relatively stable
throughout the Harbor with little variation during a dry period. So far, no sampling has been conducted during a
wet weather event to assess the variability due to freshwater inputs.
LONG ISLAND SOUND
The Connecticut DEEP ship surveys complement the Long Island Sound acidification program, and the data are
used for cross-calibration of temperature, salinity, pH, and DO. In addition, a CTD probe with a calibrated pH
sensor is lowered into the water column near the buoy about once a week in the summer. Discrete samples were
not collected in 2019.
BARNEGAT BAY
Weekly discrete samples were collected for laboratory analysis of DIC (coulometer) and pH (spectrophotometer)
during the 2017 sampling season. Unable to collect discrete samples during 2019.
TAMPA BAY
Discrete samples are collected every 2 to 4 weeks at the Tampa Bay station and approximately quarterly at the
offshore location. Samples are analyzed for pH, DIC, TA, and total nitrogen and phosphorus. Spectrophotometric
pH is measured in the field.
MOBILE BAY
Discrete samples will be collected monthly at Middle Bay Light and at approximately 10 other stations across the
salinity gradient. Samples will be analyzed for carbonate system variables, as well as dissolved and particulate
inorganic and organic nutrients, dissolved and particulate organic carbon, and phytoplankton biomass and
production rates, and community respiration rates.
Monitoring Methods

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DISCRETE SAMPLING
COASTAL BEND BAYS
Discrete water samples have been collected since May 2014 through present. Biweekly to monthly field
sampling at five System-Wide Monitoring Program (SWMP) sites, including the UTMSI research pier, located
within the Mission Aransas National Estuarine Research. Discrete sampling has continued since the destruction
of a pier where the sensor deployment was located. Eight or nine months of biweekly sampling and three months
of monthly sampling have been conducted. Discrete samples are analyzed for DIC, pH, and TA.
Duplicate water samples at both the pump inlet depth using a Van Dorn sampling bottle and inside the cooler
where the instruments are located were taken right after the last whole hour measurements before sensor
cleaning or retrieval. Water temperature and salinity were collected using a handheld YSI data sonde at
the pump inlet depth and inside the cooler. Water sample collection followed standard protocols for ocean
carbonate chemistry studies (Dickson et al., 2007). 250 mL ground glass borosilicate bottles were used and
overflow of at least one bottle volume was ensured. After sample collection, 100 |_iL saturated mercury chloride
(HgCL) was injected into the sampling bottle to arrest biological activity, and Apiezonฎ grease was applied
to the bottle stopper, which was then secured to the bottle using a rubber band and a nylon hose clamp
(Hu et al., 2018).
SANTA MONICA BAY
Discrete water grab samples are collected quarterly and sent to the City of Los Angeles Environmental
Monitoring Division for analysis of pH and alkalinity. In addition, LACSD conducts CTD casts quarterly at a
nearby station to validate the moored sensor data.
SAN FRANCISCO ESTUARY
Discrete samples are collected every six weeks, at a minimum, at the surface and at depth with a Niskin bottle
adjacent to the pH sensors. The duplicate or triplicate samples are collected in borosilicate bottles, fixed
immediately with HgCL and stored for later analysis of pH and total alkalinity. Chlorphyll a and nutrient samples
are also collected. A CTD cast is also done at the time of sampling. Sampling coincides with service visits.
TILLAMOOK ESTUARY
At EPA ORD deployment, duplicate discrete water samples are collected every 2 to 4 weeks during the
servicing/cleaning of the instruments. Water samples are collected in-situ, adjacent to the sensor array using
an 8-liter Niskin bottle. Duplicate water samples are transferred to 330 mL amber glass bottles using standard
methods for dissolved gas sampling and poisoned with 30 |_iL of HgCL and capped. The water samples are
analyzed for pC02 and DIC by US EPA using a carbonate chemistry analyzer designed and built by Burke Hales
(Oregon State University).
At the Tillamook Estuaries Partnership monitoring location water is also filter through a Whatman Puradisc
25 GF/F disposable filter device using a plastic 60 ml syringes with luer-lock connector. The water sample is
collected in a HDPE 30ml wide mouth Nalgene bottle. The samples are then placed in a -20-degree freeze for
end of season analysis for dissolved nutrient.
Monitoring Methods

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3.5
Data Collection, Processing and Storage
Six of the ten NEPs have wireless telemetry capability
which is described in the table below. The four NEPs
without telemetry (Casco Bay, Coastal Bend Bays, Santa
Monica Bay, and Tillamook Estuary) retrieve the sensors
on a regular basis, and the data are downloaded directly
from the sensors or data logger. Sensor and discrete
sample data are stored in-house at the NEPs or at
partner organizations (e.g., US EPA ORD, universities,
state agencies). Telemetered data from some of the
NEPs are then uploaded and hosted on university or
agency websites. Some of the websites provide data
query, download, and graphic capabilities.
Each NEP site follows their own quality assurance/
quality control procedures. In general, these NEP sites
conduct annual recalibration of the sensors with the
manufacturer and use calibration coefficients provided
by the manufacturer for sensor deployments. As
described in Section 3.4, discrete samples are collected
to validate the in situ sensor measurements. Some
monitoring groups check instrument performance in a
tank prior to and subsequent to deployment. Data from
sensors are reviewed, flagged, and verified by using
Methods
various techniques including rejecting data beyond
specified ranges, rejecting data if inconsistent with
known chemistry of the system, and identifying outliers
by examining interrelationships between parameters.
Examples of quality assurance/ quality control
procedures can be found here:
Tampa Bay: https://pubs.er.usas.aov/publication/
ofr20191003
Barnegat Bay: https://www.barneaatbavpartnership.
org/protect/barneaat-bay-science-and-research/quality-
control-and-qualitv-assurance/
Casco Bay: https://www.cascobavestuarv.org/
publication/ocean-and-coastal-acidification-monitorina-
in-casco-bav-cbep-qualitv-assurance-project-plan-
qapp /
A description of the data collection, processing, and
storage methods used by each of the NEPs is presented
below, followed by the challenges and lessons learned
regarding data management, data interpretation, and
data quality.
DATA COLLECTION, PROCESSING, AND STORAGE METHODS
CASCO BAY
Data Collection Interval: Hourly
Data Retrieval: No telemetry because the dock at Southern Maine Community College does not have the
power and data links at this time. Every 4 to 6 weeks, the system is retrieved, and data are downloaded from the
instruments in text file format. Each instrument produces a time stamp and data stream.
Data Processing: Data are run through a series of Matlab programs to produce a final hourly Excel file. The
pH data from the SeaFET sensor are corrected for salinity. The SeaFET software corrects for oxygen. Pulled into
Level 1 file: raw data corrected for temp, and salinity; Level 2: flag data gaps or bad data; Level 3: final data
product. Use the discrete pH data to do a ballpark matchup with pH sensor data.
Omega is calculated on an hourly basis using a Matlab computer software package called C02SYS that is
based on dissociation constants of carbonic acid (Lewis and Wallace, 1998). Using simultaneous measurements
of pH, pC02, temperature, and salinity. C02SYS calculates aragonite and calcite saturation state, as well as total
alkalinity and DIC.
Data Storage and Access: Data are currently stored and processed at UNH, but ultimately sent to Casco Bay
Estuary Partnership. There is a desire to integrate the data into the NERACOOS data architecture as well.
3
m. Monitoring Methods

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DATA COLLECTION, PROCESSING, AND STORAGE METHODS
MASSBAYS
Data Collection Interval: 15 minutes
Data Retrieval: Cellular telemetry will transmit the collected data to the Center for Coastal Environmental
Sensing Networks (CESN) at University of Massachusetts, Boston in real time.
Data Processing: No data collected to date.
Data Storage and Access: Data will be stored at CESN at UMass Boston. Following data QA/QC, the data will
be submitted to NERACOOS. That organization has agreed to include MassBays' data in a new web-based
module to share coastal acidification data. The data will be made public through neracoos.org.
LONG ISLAND SOUND
Data Collection Interval: 15 minutes
Data Retrieval: Data telemetry
Data Processing: Data are initially stored in a database as provisional. As QA/QC protocols are developed and
installed, the data are reviewed and flagged as to quality and archived for public access.
Data Storage and Access: The pH data are provisional and are not publicly available from the internet.
Data for other parameters are shared publicly via the University of Connecticut LISICOS website
(http://lisicos.uconn.edu'). Complete dataset is archived at University of Connecticut (Jim O'Donnell's Lab).
BARNEGAT BAY
Data Collection Interval: 30 minutes
Data Retrieval: The data are both stored internally and transmitted to a Campbell datalogger. A cellular
telemetry network relays the data on an hourly basis back to the NEP.
Data Processing: [No information provided.]
Data Storage and Access: Data are stored with Dr. James Vasslides at Ocean County College. Data from the
YSI instrumentation is shared with the NJ DEP webpage, where it is possible to view data in real time and share
archived post-QC data (http://nidep.rutaers.edu/continuous/). The C02 Pro and SeaFET data are not currently
available on the website; there is a note indicating that these data can be requested.
Monitoring Methods

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DATA COLLECTION, PROCESSING, AND STORAGE METHODS
TAMPA BAY
Data Collection Interval: Hourly
Data Retrieval: The Tampa Bay Land/Ocean Biogeochemical Observatory (LOBO), Ocean Carbon System
(OCSv2) system uses an Integrated Seabird Storx data logger to collect variable and common time and date
and communicates with the LOBOviz cellular telemetry system. The OCSv3 system is integrated into the existing
COMPS C12 Campbell Scientific logger and satellite telemetry system. The OCSv3 data are served online on the
existing COMPS C12 data website and transmitted via the NOAA GOES satellite system.
Data Processing: Data delivered via telemetry are raw data values as output from each sensor. All raw
sensor data are synthesized approximately quarterly and undergo preliminary QA/QC using a manual two-
step procedure to remove outliers. During the first step, data beyond acceptable measurement ranges for the
sensors are flagged to indicate bad data. After preliminary QA/QC of sensor data, advanced data processing is
performed. The SeapHOx pH data are corrected to salinity and temperature of the Sea-Bird SBE 37-SMP-ODO
MicroCAT C-T-ODO (P) Recorder data through a MS Excel macro provided by Satlantic. The Satlantic macro
is also used to perform a single point calibration of the SeapHOx pH data using discrete pH measurements
determined in-situ and concurrently with OCS sample acquisition. Discrete pH measurements are performed
using spectrophotometric pH methods. Once corrections have been completed, parameter data are plotted
to examine sensor performance and identify non-trending outliers. Cross validation of sensor parameters is
performed to further analyze outliers and identify questionable or bad data points. Further validation of pH
and C02 sensor data is performed by comparing sensor values to values measured in discrete water samples
throughout the duration of deployment. Discrete pH is measured using spectrophotometric measurements.
C02 is calculated from discrete measurements of pH and dissolved inorganic carbon (performed using carbon
coulometry methods).
Data Storage and Access: Land/Ocean Biogeochemical Observatory (LOBO), Ocean Carbon System (OCS)
data is provided in near real-time through an interactive website call ed LOBOviz at http://tampabav.loboviz.
com/. LOBOViz can be used to see data in real time and graph any parameter using archived data. These data
are not quality assured, but incorrect data can be excluded, for example when the sensor is being moved.
Quality assured data are archived at USGS and are available online as a USGS Data Release: https://coastal.
er.usas.gov/data-release/doi-P9BAFC7L/. Data quality is indicated using the data flagging approach of NOAA
National Centers for Environmental Information (NCEI) https://www.nodc.noaa.aov/GTSPP/document/codetbls/
atsppcodes/atspp qual.html
The 0CSv3 can be viewed at: http://comps.marine.usf.edu.
MOBILE BAY
Data Collection Interval: Every 30 minutes
Data Retrieval: No telemetry. Data will be stored on instruments and downloaded periodically
Data Processing: No data collected yet
Data Storage and Access: Data will be archived and made available via the ARCOS site (https://arcos.disl.org)
Monitoring Methods

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DATA COLLECTION, PROCESSING, AND STORAGE METHODS
COASTAL BEND BAYS
Data Collection Interval: Hourly
Data Retrieval: No telemetry. Data collected by the sensors (pH, pC02, salinity, and temperature) were saved
in the onboard data loggers for periodic download during biweekly or monthly trips to the UTMSI pier. During
servicing of the instruments, the SAMI-CCX and SeaFET sensors were taken out of the cooler, and the cooler
was cleaned to remove sediment. Data from the prior deployment period were then downloaded to a laptop
computer before placing the sensors back into the cooler.
Data Processing: [No information provided.]
Data Storage and Access: Real-time data not hosted online. Data are archived at Texas A&M University -
Corpus Christi.
SANTA MONICA BAY
Data Collection Interval: Hourly
Data Retrieval: No telemetry. Data are downloaded directly from the devices on a quarterly basis.
Data Processing: Data analysis is conducted by the Los Angeles County Sanitation District. An Excel
spreadsheet and Macro utility C02SYS (Lewis and Wallace, 1998) were used to calculate the Qarag levels for
every data record with a valid pH and pC02 reading (LACSD, 2019).
Data Storage and Access: Data are archived at Southern California Coastal Water Research Project (SCCWRP)
and in house.
SAN FRANCISCO ESTUARY
Data Collection Interval: 1 hr/15 minutes
Data Retrieval: Surface mooring has data telemetry. However, the NEP has been unable to connect the newer
SeaFET with the telemetry system, so pH data are downloaded from the sensor. The deep-water mooring does
not have telemetry, and the sensors are retrieved every six to eight weeks for service and data download.
Data Processing: [No information provided.]
Data Storage and Access: Telemetered data go through NOAA Pacific Marine Environmental Laboratory
(PMEL) and are uploaded to an ERDDAP server, and then broadcast on the San Francisco State University
Estuary and Ocean Science Center (EOS) webpage (http://coastalobservations.sfsu.edu/tiburon). Data are
archived on the ERDDAP server (https://oceanview.pfea.noaa.aov/erddap/tabledap/rtcco2buov.htmn and are
sent to the Central and Northern California Ocean Observing System (CeNCOOS) data portal as well.
(https://data.cencoos.ora/'). The NEP downloads and stores the data locally on Cloud-based servers.
Monitoring Methods

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DATA COLLECTION, PROCESSING, AND STORAGE METHODS
TILLAMOOK ESTUARY
Data Collection Interval: 15 minutes
Data Retrieval: No telemetry. During regular 2-4-week servicing, data are downloaded from the sensors.
Data Processing: Custom Matlab programs have been coded to post-process SeaFET pH data (both internal
and external) using factory, in-situ check sample, and laboratory CRM calibration coefficients. Appropriate
corrections for temperature, salinity, and pressure are applied. pH results are compared with in-situ check
samples for measurement offset and/or drift. The SAMI Client program is used to post-process the
SAMI-CCX data.
Data Storage and Access: Real-time data are not hosted online. The downloaded data are archived at the
US EPA ORD and will be transferred to the NEP for archiving. Oregon Department of Environmental Quality
(DEQ) has agreed to support data management and long-term data storage for the project. DEQ will assimilate
continuous and discrete data from the project into its Ambient Water Quality Monitoring System (AWQMS). The
AWQMS database is publicly accessible and will be used for data sharing and storage.
3.6
Cost Information and Funding Sources
Understanding the full cost of coastal acidification monitoring with continuous sensors requires characterization not
only of the capital cost of the equipment, but also the cost of regular maintenance and service, data collection, and
analysis. Below is a summary of approximate cost information provided to EPA by the NEPs identified in this report
for the acquisition, calibration, maintenance, and operation of their acidification instruments. In addition, examples of
funding sources that these NEPs use to conduct these programs are also provided.
Equipment/Sensor Approximate Cost
•	pH sensor: $11,500—$12,000
•	pC02 sensor: $15,000-$17,500
•	Telemetry system: $12,500-$15,000
•	YSI Exo2 sondes and probes: $28,000
•	Frame fabrication: $4,000-$6,500
•	Mounting package hardware: $2,500
•	Installation: $600-$800 in materials and $750 in labor.
•	Significant cost savings have been achieved by using existing moorings or buoys and as more experience is
gained in the deployments.
3
Monitoring Methods

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Annual Calibration Approximate Cost
•	pH sensor: $1,500-$3,000
•	pC02 sensor: $1,000-$2,500
•	YSI Exo2-$750
•	EcoPAR:$625
•	CT (Conductivity, Temperature) Sensor: $350
Annual Maintenance and Operations Approximate Cost
•	Personnel: Typically, two technicians are needed for field, lab and data analysis work
(e.g. $40-70,000/year + fringe benefits, indirect costs per person, this estimate varies)
•	Discrete sampling-$7,000
•	Laboratory costs: $2,000 (such as consumables; Dickson Certified Reference Material (CRMs))
•	Equipment replacement and repair: See equipment cost above
•	Telemetry annual maintenance fee for web and technical service-$2,000 (less in some cases)
Funding Sources
•	EPA Office of Wetlands Oceans and Watersheds, Ocean and Coastal Acidification program funding for sensor
purchase and EPA Office of Research and Development
•	EPA funding CWA Section 320 Comprehensive Conservation and Management Plan (CCMP)
•	The NEPs provide in-kind match of staff time, laboratories or vessels
•	Some NEP partners provide funding
•	Regional Integrated Ocean Observing Systems (e.g. Central and Northern California Ocean Observing System
(CeNCOOS) support for San Francisco Bay)
Monitoring Methods

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Deployment and Data Management
Challenges and Lessons Learned
4.1
Deployment Challenges and Lessons Learned
was seen as a very valuable asset to allow the NEPs to
Several of the NEPs identified in this report experienced
challenges deploying their equipment and have
developed unique approaches to resolving these
problems. Their experiences are lessons for future
monitoring efforts. A top challenge was found to be
biofouling which inhibits effective sensor operation.
These NEPs addressed this issue with frequent cleaning
and by working directly with the manufacturers to
develop copper fittings, using copper duct tape,
sheets and antifouling paint. Other challenges were
difficult weather conditions, such as winter icing and
hurricanes, and red tides that prohibit dive operations.
These situations result in the temporary cessation
of the sensor deployments and consequently data
gaps. Two NEPs avoided biofouling and inhospitable
environmental conditions by deploying the instruments
in weatherproof coolers with flow-through systems. The
ability to incorporate telemetry to transmit data real-time
know about an equipment failure and or other reason
for a lapse in data collection. However, incorporating
telemetry can be a challenge if there is not a land-
side power source or insufficient solar power at the
deployment site. To address several of the challenges,
these NEPs recommend purchasing redundant sensors
so that one sensor can be exchanged for another
if cleaning is needed due to biofouling, there are
delays in calibration or repair of the equipment at the
manufacturer, a malfunction occurs or other issues.
This practice minimizes any gaps in data collection.
However, all of these NEPs found it cost prohibitive to
purchase additional sensors. Below is a summary of the
various deployment challenges and lessons learned by
the NEPs conducting coastal acidification monitoring.
Measuring Coastal Acidification Using In Situ Sensors
In the National Estuary Program

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CHALLENGES
LESSONS LEARNED
COSTS
•	The cost of sensors is changing, but they remain
expensive.
•	As a result, when the sensors are out of the water
for calibration, maintenance, or data download
(if there is no telemetry), then data gaps result. It
is often cost prohibitive to purchase a redundant
sensor.
•	It is difficult to find an entity to insure the equipment.
Tillamook Estuaries Partnership can Casco Bay
insured their equipment.
•	One of the buoys (ARTG) is pulled during the winter
(Long Island Sound).
•	It is difficult to predict repair costs for any given
funding year.
•	Building an innovative system for year-round
deployment is more costly and challenging,
therefore taking longer (MassBays).
•	Opt for sensor redundancy and telemetry at each
site, if budget allows, to solve many challenges
(multiple NEPs).
•	Develop better cost estimates for long term
maintenance and replacement of the sensors
(Santa Monica Bay).
ENVIRONMENTAL CONDITIONS
•	Icing during winter can lead to equipment freezing
(Casco Bay, MassBays, Barnegat Bay).
•	Pier where sensors were deployed was destroyed
by Hurricane Harvey (Coastal Bend Bays).
•	It is difficult to get access to sensors in the fall and
winter due to weather (Long Island Sound).
•	The dock can get significant splash over during
storms and the pumping housing can warp due to
cold temperatures (MassBays).
•	During red tide, no dive operations can occur
(Tampa Bay).
•	Storm events dragged moorings, with one lost.
(Tillamook Estuary).
•	Pull equipment in winter or deploy in a cooler on a
pier (Casco Bay, Long Island Sound, MassBays,
Barnegat Bay).
•	Use a flow-through pumping system so that they
sensors are not immersed in seawater (MassBays).
•	To avoid downtime due to red tide, reinvent
mounting package. Installed lever arm to raise
equipment to surface for maintenance during red
tide. This helped to reduce lapses in data and
equipment failures due to biofouling. The use of
scrap materials resulted in a cost savings of $1000
(Tampa Bay).
Deployment and Data Management Challenges and Lessons Learned

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CHALLENGES
LESSONS LEARNED
LOCATION/SITING
•	Deployment location has 12 ft tidal ranges,
creating very shallow (<3 ft) conditions at low tide
(MassBays).
•	Deployment of array was selected so not to be
unduly influenced by point sources and to avoid
discharge plumes (Santa Monica Bay).
•	Due to boat strikes on the mooring, equipment
was breaking free from mooring and from the buoy
(Santa Monica Bay).
•	Tillamook Estuary is a shallow bay with strong tidal
forcing, difficult to navigate. The initial EPA ORD
deployment site was chosen at a site that is always
submerged and not emergent. The additional
deployment by Tillamook Estuaries Partnership was
placed in a more central location in the bay
•	Use floating pump for constant depth sampling
(MassBays).
•	Use existing pilings or buoys for equipment
deployment that results in cost savings and co-
located data (Long Island Sound, Tampa Bay,
Santa Monica Bay, Tillamook Estuary). For example,
Tampa Bay saved $200,000 by using an existing
piling for their deployment.
•	To try to avoid boat strikes, use a radar reflector
surface spar buoy and file a notice to mariners
with the Coast Guard identifying the location of the
mooring (Santa Monica Bay).
LOGISTICS
•	Design and construction of a flow-through system
took longer than anticipated (MassBays).
•	Concern about the adequacy of solar power to
run telemetry resulted in redesigning to make
the system run on the electrical grid. Logistical
challenges to obtain power resulted in a longer
process to deploy the system (MassBays).
•	No real-time power/data available, no running water
at the pier. If power was available, the site would be
ideal for very robust sampling (Casco Bay).
•	Occasional pump or sensor failures; discovered
only after checking on the site (no telemetry
to diagnose problems in real time) (Coastal
Bend Bays).
•	No spare instrumentation when malfunctions
happen. At the mercy of the manufacturer to fix
equipment and ship back (San Francisco Estuary,
Barnegat Bay, Casco Bay).
•	Sensor and equipment outages - cost for charter on
boat for extra day to travel and service equipment
(San Francisco Estuary).
•	Use sensor redundancy and telemetry at each site
to solve many challenges (multiple NEPs).
•	Consider reliability of solar vs. landside power to
run telemetry system. Chose year-round landside
power to be installed at the deployment pier
to avoid concerns of the inadequacy of solar
(MassBays).
•	Remove data during known instances of pump
failure (Coastal Bend Bays).
Deployment and Data Management Challenges and Lessons Learned

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CHALLENGES
LESSONS LEARNED
DESIGN
•	Constructing a custom-made system to fit the
sensors fit inside a weatherproof housing resulted in
increased time and cost versus using off-the-shelf
materials (MassBays).
•	Integrating sensors together (three different
manufacturers) resulted in uncertainty about
where to send the array for service and calibration
(Barnegat Bay).
•	Delay in deployment due to manufacturer's error in
instrument assembly (Santa Monica Bay, Tillamook
Estuary).
•	Uncertainty regarding battery life for long
deployments (Santa Monica Bay).
•	The SeaFET instrument flooded. The NEP staff did
not realize there was a flooding issue, because no
telemetry is available at the deep-water deployment
location and the instrument was deployed for a
long time period before the issue was found. The
instrument was sent to Seabird, who did not know
why it flooded. They said it was a manufacturing
error, and they would fix it for free (San Francisco
Estuary). Flowever, Seabird did not provide a free
replacement in a similar situation at the Tillamook
Estuaries Partnership deployment.
•	Due to the problems experienced with surface
deployment of the SeaFET (not even under
pressure) and concerns about the design of
the SeaFET case, a non-commercial case was
deployed multiple times mostly without incidence
(San Francisco Estuary).
•	Modify sensors to fit into the weatherproof housing
unit (MassBays).
•	Ensure these sensors are robust for long-term
deployments (Long Island Sound).
•	Be creative. For example, develop a sliding rail
system to allow easy access for cleaning the
devices quickly and efficiently (Barnegat Bay).
•	Encourage two-way learning exchanges between
the sensor manufacturers and researchers
(Tampa Bay).
•	Confidently secure sensors to the mooring and
safely retrieve by using a custom strongback cage
and utilize telemetry to alert NEP staff of instrument
failure (Santa Monica Bay). Consider deploying
a non-commercial version of the sensor case
(particularly the SeaFET case) due to design flaw
with commercial case (San Francisco Estuary).
•	Battery life will be tested when the instruments are
serviced in July (Santa Monica Bay).
Deployment and Data Management Challenges and Lessons Learned

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CHALLENGES
LESSONS LEARNED
BIOFOULING
•	Double the number of sensors to minimize the
impact of biofouling because the sensors could
be swapped out and cleaned in the lab, if budget
allows (multiple NEPs).
•	Frequently clean the sensors (e.g., every two
to three weeks during summer/fall) to remove
biofouling (Casco Bay, Long Island Sound,
Barnegat Bay, Tampa Bay, Tillamook Estuary). For
Casco Bay, cleaning every 4-6 weeks was more
realistic given time and resource constraints.
•	Deploy sensors in PVC tube with antifouling paint
(inside and out) (Barnegat Bay).
•	Develop a sliding rail system (Barnegat Bay)
or pully system (Tillamook Estuary) to allow the
cleaning of the devices quickly and efficiently.
•	To overcome biofouling, work with manufacturer to
develop copper fittings to use at instrument flow
inflow points. Reinvent mounting system using
copper plating and wrap instruments in copper
tape to combat biofouling (Tampa Bay).
•	Increase flow rate through SeapHOx by routing
outflow from C02Pro to SeapHOx to help prevent
sedimentation inside of measurement chambers.
•	Deploy the instruments in a cooler to reduce
biofouling (Coastal Bend Bays).
•	Use a flow-through pumping system to avoid
biofouling on sensors altogether (MassBays).
•	Swap out the YSI sensor and replace it with another
pre-calibrated YSI during service trips instead
of cleaning one sensor biofouling at each visit,
especially during seasonal increased temperatures
when biofouling increases and substantial drift in
the salinity signal can occur (Coastal Bend Bays,
Tillamook Estuary).
•	Make modifications such as copper sheeting on
key parts of the instruments, and a minimal amount
of slow-dissolving tributyltin in the SeapHOx water
intake opening (Santa Monica Bay).
•	Keep spare instruments so one can be swapped
out while one is being serviced and cleaned in the
laboratory (Long Island Sound, Tillamook Estuary).
•	Biofouling of the sensors is a challenge for most of
the NEPs, including Santa Monica when the sensors
were deployed at the 50 feet depth (but not at the
200-foot depth).
•	The pl-l and pCO, sensors both fouled, which led
to membrane or sensor failure (Long Island Sound,
Tampa Bay, Tillamook Estuary).
•	C02 probe had barnacle growth inside, which
punctured membrane (Tampa Bay).
•	Main challenge was biofouling with CO., Pro CV -
high eutrophic estuarine environment
(Barnegat Bay).
•	Siltation which appears to be uneven across
devices (Barnegat Bay).
•	Potential siltation issue in which sediment
accumulated in the pH sensor housings where it got
partially buried (Casco Bay).
Biofouling	Biofouling
(Casco Bay)	(Santa Monica Bay)
Biofouling Biofouling	Biofouling
(Long Island (Barnegat Bay)	(Tillamook Estuary)
Sound)
Deployment and Data Management Challenges and Lessons Learned

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CHALLENGES
LESSONS LEARNED
COLLABORATION/MAINTENANCE
•	Most of the NEPs have found that manufacturers'
calibration of the sensors, which is usually
conducted annually, is both costly and time
consuming. It can take months to get the calibrated
instrumentation back from the manufacturer, which
results in large breaks in the data when back up
instruments are not available. For example, Casco
Bay indicated that the Satlantic SeaFET and SAMI-
C02 both have a 2 to 3-month turnaround time for
calibration that can result in data gaps.
•	SAMI-CO.-, performance pre-check is done at UNH
Coastal Marine Lab (Casco Bay).
•	SeapFlOx and C02Pro validation is performed at
USGS Carbon Lab prior to deployment (Tampa Bay).
•	The instruments are not satisfactorily robust yet
and require a lot of fixing and cleaning.
(Long Island Sound)
•	The NEPs must rely on the manufacturers for annual
maintenance (Santa Monica Bay).
•	The NEP saw biofouling issues starting with the CO,
sensor (Barnegat Bay).
•	Issues related to ionic strength/salinity dependence
of SeaFET and SeapFlOx pH measurements. Tidal
flushing results in rapid salinity changes that exceed
the response time of the external reference electrode
(Tillamook Estuary).
•	Use a Seabird instrument to perform the calibration
of the SeaFET. Use a certified Tris buffer from A.
Dickson to perform a one-point calibration check
of SeaFET, but this is not always a reliable solution
(Casco Bay).
•	Use a flow-through design to reduce the need for
factory-dependent calibration (the system includes
internal standards for calibration of the IR detector)
(MassBays).
•	Use a redundant SAMI sensor deployed side-by-
side in the laboratory to compare the results of both
sensors (Tillamook Estuary).
•	Participate in monitoring partnerships to advance
the technology (Long Island Sound).
•	Only use pHint measurements with SeaFET and
SeapFlOx. Use multiple calibration coefficients to
calculate pH, including those from factory, in situ
check samples analyzed for pH, and lab-based
Dickson CRM checks (Tillamook Estuary).
•	Use discrete water sampling and concurrent sensor
measurements in the laboratory to validate system
performance (Tampa Bay).
•	Collect adequate, contemporaneous QA/QC
samples to compare to sensor results to address
calibration and biofouling errors (Casco Bay).
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CHALLENGES
LESSONS LEARNED
INSTRUMENT MALFUNCTION/FAILURE
•	In 2015, the SAMI-CCX had an issue with blank
readings and UNH removed the sensor in post-
processing (Casco Bay).
•	In 2016, the SAMI-C02 temperature sensor failed
and UNH removed the data in post-processing
(Casco Bay).
•	The SeaFET was retrieved on January 25, 2017.
Readings were consistently two times measurement
units higher than the EX02 sensor. The instrument
was serviced at Seabird from January 30, 2017 to
June 2017 and found the device had a bad DuraFET
sensor (Barnegat Bay).
•	The CV-Pro was down for two months due to user
error in the end of the summer of 2017, and then
a bad power supply board in Spring 2018. In the
summer of 2019, there was a mystery short that has
taken out the telemetry system, CV-Pro, and SeaFET
(Barnegat Bay).
•	Lapses in telemetry were periodically caused
by flooding of the modem, and or failure of
communications and instrument cables due to
biofouling (Tampa Bay).
•	Field cleaning introduced moisture into the unit. The
problem was quickly diagnosed by Pro-Oceanus
(Barnegat Bay).
•	Encourage two-way knowledge exchanges between
the sensor manufacturers and researchers
(Tampa Bay).
•	Identify the weaknesses of the sensors in order to
sustain long-term observing systems. Encourage
more sensors to be built and deployed so that
they become reliable. This project has moved
advances in the technology forward substantially
(Long Island Sound).
•	Comparisons between YSI pH and SeaFET/
SeaPFlOX are useful for detecting sensor problems,
as well as inter-relationships between variables
(Tillamook Estuary).
•	Be careful to keep the SeaFET sensor wet during
retrieval (Casco Bay).
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4.2
Data Management Challenges and Lessons Learned
DATA MANAGEMENT CHALLENGES
•	There is a backlog of samples for TA/DIC so
calculations for the saturation state (or omega) are
not complete (Casco Bay).
•	Telemetry and data logger breakdowns; wait for
commercial provider to fix (Barnegat Bay).
•	Incompatible data format and firewall issues prevent
host institution from posting collected data to their
website (Barnegat Bay).
•	Telemetry is user friendly and versatile, but when it
breaks, need to wait for commercial provider to fix
connection (Tampa Bay).
•	Issues with individual sensors not connecting to the
telemetry system. For example, sensor firmware
update broke the code that links to the instruments.
This happened to the pH instrument, which was
collecting and sending raw files but connection to
LOBOviz was broken after firmware updates.
•	Changing telemetry system because Seabird is
closing offices that designed and engineered
LOBOviz data management software, prefer to
control the system in-house (Tampa Bay).
•	No telemetry at the site at any point during the
data collection period. Unable to identify and
diagnose equipment and pump failures in real-
time (for example, four months of data lost due to
biofouling contamination) (Coastal Bend Bays,
Santa Monica Bay).
•	Lack of funding for data quality control and data
management (San Francisco Bay).
DATA MANAGEMENT LESSONS LEARNED
•	Ensure that institutional knowledge and
documentation exists before using or changing
telemetry systems (Barnegat Bay).
•	Use a telemetry system that you and your partners
have the ability to fix if issues occur. For example,
Tampa Bay is looking to move to a cellular telemetry
system at University of South Florida, funded by
Southeast Coastal Ocean Observing Regional
Association (SECOORA) because it can be fixed in-
house. The system is run by NOAA and universities.
•	Use the Ocean Acidification Information Exchange
to post your web data and share comments about
when instruments down or in lab (Tampa Bay).
•	Share real-time updates related to data (Tampa Bay).
•	Flave a system with telemetry, it's important for data
continuity (San Francisco Estuary).
•	Partner with the regional IOOS systems. CeNCOOS
has invested in the data system, so NEP's level
of effort to post data has been small. One of their
priorities is to share the data (San Francisco
Estuary).
•	Understand that all of the regional IOOS systems
run differently and have different governance
and different priorities. It depends on the regional
organization how it would work (San Francisco
Estuary).
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4.3
Data Interpretation Challenges and Lessons Learned
DATA INTERPRETATION CHALLENGES
•	Guidance from EPA on which data to report would
be helpful (Casco Bay).
•	Development of management and outreach ideas for
the next report (Casco Bay).
•	Lower quality sensors are picking up diurnal
changes and algal blooms, but to calculate
saturation state, more expensive equipment may be
required (Casco Bay).
•	Comparison of data between NEP, Friends of Casco
Bay and Bigelow, which use instruments of varying
precision (Casco Bay).
•	Measuring changes is difficult because of the large
fluctuations in pH. A decade of data will be required
to detect trends in pH and the link between DO and
pH (Long Island Sound).
•	Comparison of discrete versus continuous data
- different temporal scales and methodologies
(Barnegat Bay, Tampa Bay).
•	Lack of funding for data interpretation
(San Francisco Bay).
•	Due to strong tidal forcing and highly advective
environment, rapid changes in carbonate chemistry
can occur which hinders assessing accuracy
through comparison of discrete and continuous data
(Tillamook Estuaries).
DATA INTERPRETATION LESSONS LEARNED
•	Due to annual variability, be careful about making
generalizations about the data from one year to the
next (Casco Bay).
•	Ensure that other types of associated in situ data
(chlorophyll a, nitrogen, PAR) are collected in order
to interpret acidification in the context of inshore
processes, such as hydrodynamics, mixing, primary
production, etc. (Casco Bay).
•	Use high quality equipment, like these sensors, to
attract high quality partners with expertise
(Casco Bay).
•	Look at similar coastal acidification questions across
the country with common hypotheses (Casco Bay).
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4.4
Data Quality Challenges and Lessons Learned
DATA QUALITY CHALLENGES
•	Writing the Quality Assurance Management Plan
(QAPP) for this monitoring program was a challenge
(Casco Bay).
•	Efforts to cross calibrate with other organizations
is a challenge when they are using lower quality
equipment (comparing apples and oranges)
(Casco Bay).
•	The SeaFET was shipped from the manufacturer with
bad sensors. Redundant measurements made on
EXO instrument and discrete samples showed lots of
drift in the SeaFET measurement (Barnegat Bay).
•	The pH and C02 data validation (in situ versus
discrete) (Tampa Bay).
•	Data needs to be removed during known instances
of pump failure (Coastal Bend Bays).
•	Observed potential issues with SeapFlOx pH data
collected during the latter part of the second year
that are being addressed with the manufacturer
(Santa Monica Bay).
•	Delays in receiving the discrete sample data from an
analytical laboratory hinder ability to detect issues
with instrumentation (Tillamook Estuary).
DATA QUALITY LESSONS LEARNED
•	Attract high quality monitoring partners like UNH,
to bring a level of expertise that is unparalleled
(Casco Bay).
•	Use high quality data to show that the NEP is
obtaining a good understanding of the carbonate
system in the estuary (Casco Bay).
•	Select periods with no data collection problems
(such as biofouling) to highlight high quality data
(Barnegat Bay).
•	Improve accuracy of in situ versus discrete data
by improving the timing of sampling to avoid fast
currents, improving temperature control, and
shortening the length of the sampling tube from
the boat to the sensor. Time sampling to slack tide
(Tampa Bay).
•	Need to correct discrete pH measurements analyzed
in the lab to in situ temperature and pressure before
comparison with field sensor measurements (Santa
Monica Bay).
•	Discrete samples from Tillamook are now being
analyzed for pC02 and TC02 by US EPA ORD
to reduce delays in analysis of discrete samples
(Tillamook Estuary).
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Monitoring Partnerships and
Public Outreach	
5.1
NEP Monitoring Partnerships
In order to conduct these intensive and technologically advanced programs, the NEPs identified in this report have
built partnerships to share information and maximize limited funds. Below is the list of the NEP's partners and their
roles in the coastal acidification monitoring programs.
NEP MONITORING PARTNERS
EAST COAST
Casco Bay	• U.S. EPA Region 1 (project management)
•	University of New Hampshire (conducts the monitoring, sensor maintenance, data
collection and processing)
•	Southern Maine Community College (location for monitoring)
MassBays	• The Center for Coastal Environmental Sensing Networks (CESN), University of
Massachusetts Boston (system design, construction and deployment)
•	North & South River Watersheds Association (train citizen scientists for the collection of
discrete samples)
•	U.S. EPA-Office of Research and Development (ORD) Atlantic Ecology Division,
Narragansett, Rl (discrete sample analysis)
Long Island Sound • University of Connecticut (conducts the monitoring including operating the buoy
system, maintaining instruments, and data sharing)
•	University of Connecticut Long Island Sound Integrated Coastal Observing System
(LISICOS) (provides buoys for instrumentation deployment, data hosting)
Barnegat Bay	• NOAA NMFS James J. Howard Marine Sciences Laboratory and Milford Laboratory
(quality control, discrete sampling, data analysis)
•	N.J. Department of Environmental Protection, Bureau of Marine Water Monitoring
(provides technical assistance with telemetry systems and houses real-time data and
archived data portal)
GULF OF MEXICO
Tampa Bay	• U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center (conducts
monitoring, data collection and data analysis)
•	University of South Florida Physical Oceanographic Real-Time System (PORTS) and
the Coastal Ocean Monitoring and Prediction System (COMPS) provides use of existing
monitoring platforms for deployment of monitoring packages and annual research
vessel support for offshore system maintenance.
•	USF Center for Ocean Technology provides engineering and data management
assistance for linkage of offshore monitoring system to the COMPS telemetry, data
delivery and data storage system.
Measuring Coastal Acidification Using In Situ Sensors
in the National Estuary Program

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NEP MONITORING PARTNERS
Mobile Bay	• University of South Alabama (conducts monitoring, data collection, and data analysis)
•	Alabama's Real-Time Coastal Observing System and Dauphin Island Sea Lab provides
the web site for hosting the data (https://arcos.disl.org). the platform for deploying the
instruments, and ship time and technician support for maintaining the instruments
•	Funding to purchase the instruments, perform the bay-wide discrete sampling, and data
analysis and interpretation is provided by a competitive grant from the NOAA Restore
science program.
Coastal Bend Bays • Texas A &M University—Corpus Christi (conducts the monitoring, data collection and
data analysis)
•	University of Texas Marine Science Institute (UTMSI) (provided the deployment platform
and helped with designing and mounting the monitoring structure on their research pier)
•	Mission-Aransas National Estuarine Research Reserve (MANERR) (provided monitoring
data [salinity and temperature] for cross validation)
WEST COAST
Santa Monica Bay • City of Los Angeles Environmental Monitoring Division (analyzes discrete
measurements)
•	Los Angeles County Sanitation Districts (maintains the OAH sensors and mooring,
including deployment, retrieval, all servicing and data downloading, conducts
supplemental monitoring (e.g. CTD), and manages data analysis)
•	Southern California Coastal Water Research Project (SCCWRP) (archives the data)
San Francisco	• Estuary and Ocean Science Center, San Francisco State University (conducts the
Estuary	monitoring, data collection and data analysis)
•	Coastal Marine Sciences Institute, University of California Davis (shares staff, technical
expertise, conducts data analysis)
•	CeNCOOS (houses the data, QA/QC of telemetered data)
Tillamook Estuary • U.S. EPA Office of Research and Development (ORD) Center for Public Health and
Environmental Assessment (conducts the monitoring, data collection and data analysis
of instrument deployed at Garibaldi). This is funded through US EPA Region 10 (RARE
Project) and US EPA ORD funding.
•	Oregon Department of Environmental Quality (Manages and provide long-term data
storage. Also contributes to YSI equipment maintenance)
•	Tillamook Estuaries Partnership (Acquired funding to expand project, implements
instrument deployment at second site and partnership coordination for data integration)
•	Oregon State University (SeaFET maintenance and data analysis)
•	Oregon Health Sciences University (data analysis)
•	Oregon Department of Fish and Wildlife (Project integration to state-wide strategy and
project implementation in Tillamook Bay)
•	Pacific Seafood (Project mooring and site support)
Monitoring Partnerships and Public Outreach

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5.2
Partnership Challenges and Lessons Learned
Many of the NEPs have found that establishing robust
partnerships has helped to support the execution and
advancement of their coastal acidification monitoring
programs. By working with universities, federal, state
and local governments and other organizations with
experience working with continuous monitoring systems
they have worked together to creatively advance the
equipment and deployments. The NEPs identified in
this report have expressed that that their participation
in this monitoring project has increased the perceived
importance of the coastal acidification issues in their
region. Below is a summary of the lessons learned and
challenges regarding the development of sustainable
partnerships to conduct the coastal acidification
monitoring.
PARTNERSHIP LESSONS LEARNED
•	Casco Bay has robust partnerships, such as the Northeast Coastal Acidification Network (NECAN), the Maine
Ocean and Coastal Acidification Partnership (MOCA) and Ocean Acidification Study Commission, State Ocean
and Coastal Acidification Partnership (MOCA) and Ocean Acidification Study Commission, State legislature,
aquaculture. Data are helping to fuel conversations, such as the temperature change effect on acidification.
They saw that the high-quality monitoring sensors attracted high quality partners with expertise.
•	MassBays has a strong relationship with its partners and citizen scientists which makes it easy to
coordinate. They will work with their partners to communicate this regional issue of growing importance
(coastal acidification and its impact to local shellfish resources). They have begun to communicate with the
Harbormaster and local fishermen in the area to make them aware of this project.
•	Long Island Sound has found that coordination with NOAA at the level of the regional association and university
has been effective.
•	Barnegat Bay has found that the shellfish aquaculture community, such as early life stage operators and
hatcheries, is interested in the monitoring program. The aquaculture community would like to increase
collaboration with other partners conducting water quality monitoring and be more involved. For example,
they are interested in learning more about the deployment set up of the NEPs conducting coastal acidification
monitoring.
•	Tampa Bay found that forming true partnerships is a grass roots effort, which may involve cost sharing and
in-kind funding when budgets are tight. Partnerships also provide a solid foundation for proposals. Dedicated
effort is required to identify the proper team members who are willing to participate as needed and to motivate
and facilitate partnership creation. Demonstrating a need for the monitoring work is also required in order to
obtain seed money to get started.
Casco Bay NEP established the first
inshore monitoring of acidification in the
region. Their efforts have spurred more
coastal acidification monitoring in the Bay
using the sensors by three other groups:
Friends of Casco Bay (partly funded by
CBEP), Bigelow/lsland Institute (partly to
look at influence of kelp farming); Bowdoin
College (located at marine station). This
project has helped to change regional
thinking and collaboration.
Monitoring Partnerships and Public Outreach

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PARTNERSHIP LESSONS LEARNED
•	Santa Monica Bay's acidification monitoring has allowed for the development of a collaborative, multi-
discipline team (local, state, federal, non-profit) to work together to solve a common issue. This common
interest has helped to decrease adversarial relationships between industry and regulatory groups and improve
relationships. Santa Monica Bay is also collaborating with coastal ocean acidification networks in California,
such as the Southern California Bight Ocean Acidification and Hypoxia (OAH) modeling project, and the
California Current Acidification Network (C-CAN)/Southern California Coastal Ocean Observing System
(SCCOOS), to provide data and establish future acidification monitoring locations.
•	San Francisco Estuary has found great enthusiasm and interest from the public and a diversity of stakeholders
in this work. People are becoming more interested in the lower estuary, which has been understudied. There
are also more students working on the project. The California Ocean Protection Council recently funded an
eelgrass restoration project in San Francisco Estuary that includes assessing the effects of eelgrass on pH and
carbonate chemistry and how the eelgrass may ameliorate ocean acidification.
•	A wide variety of partners are involved in Tillamook Estuary's monitoring program, including federal and
state agencies, local port authority, universities, and shellfish industry. In addition, the South Slough National
Estuarine Research Reserve (NERR) has been conducting coastal acidification work and providing Tillamook
Estuaries Partnership with information and assistance. There are also a number of statewide and regional
partnerships focused on coastal acidification and hypoxia. The Oregon Ocean Acidification and Flypoxia
Monitoring Workgroup brings monitoring partners together and helps to standardize monitoring techniques and
share lessons learned. The Oregon Coordinating Council influences state legislation around acidification and
hypoxia. The Pacific Coast Collaborative is coordinating ocean and coastal acidification and monitoring across
the west coast (Oregon, Washington, California, and British Columbia).
PARTNERSHIP CHALLENGES
•	There is a need for more robust funding and staffing for this type of long-term monitoring program. Two water
quality specialists are really required to maintain a sustainable program.
•	It is difficult to maintain consistency when monitoring, data analysis, maintenance, calibration, troubleshooting
and other critical tasks are done by part-time technicians. Without attractive pay scales, retaining experts can
be difficult.
•	It is difficult to find sustainable funding for long-term monitoring program. Coastal acidification monitoring is not
entrained in ongoing monitoring programs.
•	Research "project" funds won't support the commitment that is needed.
•	Partnerships take a long time to evolve and are quite vulnerable at the pilot stage. Sustainable, baseline
funding from the state or federal level is needed to maintain long-term monitoring program.
•	It can be difficult to gain the attention of funding agencies to support acidification monitoring because local,
state and federal agencies are interested in regulatory issues, restoration, and permitting.
•	It is important that there is a bridge between the different scientific drivers and needs of academics, local and
regional non-governmental organizations and regulators that can satisfy shorter-term scientific studies and
longer term management needs.
•	It is important to create interest among partners and stakeholders but there are challenges. It can be difficult to
get people excited about this type of monitoring. It is a challenge to determine how to publicize this monitoring
data to the partners. Long-term datasets are really needed to see trends.
Monitoring Partnerships and Public Outreach

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5.3
Public Outreach Efforts
The NEPs see that an important role they play within
their study areas is to serve as a platform to engage the
public on issues specific to their estuaries. The NEPs
have been working to share the status and progress of
their coastal acidification programs with their partner
organizations and the public via news releases and
newsletters. Initial monitoring findings are being
presented at scientific conferences and workshops, and
informally with shellfish partners and industry.
The NEPs have found opportunities to leverage
partner-coordinated events and public interest at the
deployment locations themselves to educate the
public about coastal acidification and ongoing
monitoring efforts.
The NEPs have found some challenges in engaging the
public on ocean and coastal acidification issues. It was
found that in some areas, it is difficult to get the attention
of the public because they are unaware of the status of
acidification impacts in their estuary and speaking about
climate change impacts can be a difficult topic. They
have found that the science is very complex, especially
in inshore waters. It is difficult and takes much time
to determine how to communicate monitoring results
to lay audiences. In the San Francisco Estuary, it was
found that people are more interested in the restoration
of native species and marshes and eelgrass that is
occurring in the lower estuary. There is interest in carbon
sequestration and the carbon budget of marshes and
eelgrass, but not much interest in the ocean and coastal
acidification. The public is interested in the National
Marine Sanctuary and the outflow of the bay into the
sanctuary.
Another challenge is that there are very limited funds
to do public outreach. The funding for the monitoring
has been used to get the instrumentation working
and obtaining and maintaining data quality. Good
data quality is critical for meaningful outreach. A more
comprehensive program that included outreach would
Credit: Christopher Hunt, UNH, Casco Bay
require more funds to reach the larger public. For
example, Long Island Sound communicates with the
science community and management agencies in Long
Island Sound and there is an additional cost, mainly staff
time, associated with greater participation.
These NEPs have shared the following lessons learned
in conducting outreach:
•	Use the monitoring data to fuel conversations with
stakeholders, particularly the shellfish industry
(Barnegat Bay, Casco Bay).
•	Use the monitoring data to support state legislation.
Since establishment of the Maine Ocean Acidification
Commission, the public is aware of coastal
acidification impacts, local fisherman are interested,
and acidification gets front page stories in Maine
newspapers (Casco Bay).
•	Use the deployment locations to attract attention. For
example, the monitoring at the pier provides visibility
for the monitoring program and an opportunity to
explain coastal and ocean acidification to the people
that visit the pier (Casco Bay).
•	Use a variety of media outlets and scientific
forums to share information about the acidification
monitoring, including social media (Facebook),
Bay Area Scientific Information Symposium (BASIS)
2015, Tampa Bay Regional Planning Council, Ocean
5
m Monitoring Partnerships and Public Outreach

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Acidification Information Exchange
(www.oainfoexchanae.org). University of South
Florida and Southeast Coastal Ocean Observing
Regional Association (SECOORA) news releases,
Tampa Bay Water Atlas, Gulf of Mexico Coastal
Ocean Observing System (GCOOS) meeting
management and policy committee, Science Working
Group SOCAN (Tampa Bay).
Publish articles about the monitoring in local
newsletters. For example, check out Baywire
newsletter (July-September 2016 and October-
November 2016) (Santa Monica Bay).
Participate in local events. For example, EPA ORD
participated in the 2016 and 2021 Hatfield Marine
Science Days, which is a public outreach event by
agencies. Visitors to Hatfield Marine Science Center
were given demonstrations of the coastal and ocean
acidification instruments. EPA ORD researchers
presented a summary of OA monitoring efforts and
results at the 2019 Tillamook Science Symposium.
The goal of the symposium was to promote projects
and expand partnerships. A local retired scientist
became interested in contributing volunteer time
to the project based on the symposium outreach.
Check out the 2021 presentation on Youtube.
A summary of the acidification monitoring was
incorporated into Tillamook Estuaries Partnership's
"2020 State of the Bays Report" (Tillamook
Estuary).
• Promote the monitoring program through the
education of university students and integrate into
student research opportunities. For example, Texas
A&M includes the coastal acidification project in its
class lectures. They also present the preliminary
data at scientific conferences. They have found
that although they have a short dataset, it is a good
dataset. They presented their data at the Gulf of
Mexico Estuarine Biennial Meeting in November 2018
and at the Association for the Sciences of Limnology
and Oceanography (ASLO) in February 2019
(Coastal Bend Bays).
Monitoring Partnerships and Public Outreach

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Preliminary Monitoring Results
Through their monitoring efforts to date, the NEPs and
their partners have begun to observe diel, seasonal,
and interannual variability of pH and pCQ2 and the
relationship between these two parameters. They have
also analyzed the relationships between carbonate
parameters and temperature, salinity, dissolved oxygen
and other variables that help distinguish between land-
based inputs and ocean influxes (e.g., from upwelling.
The measured parameters can also indicate biological
process such as primary production and microbial
decomposition. The preliminary monitoring data show:
•	Evidence of the correlation of temperature and
salinity with short-term (daily-weekly) and longer-term
trends in pC02 concentrations.
•	Observations of biological signals (photosynthesis
and respiration) through dissolved oxygen and pH
dynamics.
•	The relative influences of land-based sources (rivers,
runoff) versus ocean waters (upwelling).
Moreover, it is the goal of the NEPs and their partners
to analyze patterns and trends in aragonite saturation.
Aragonite saturation state is commonly used to track
ocean and coastal acidification because it is a measure
of carbonate ion concentration. As aragonite saturation
state decreases, it is more difficult for organisms to
build and maintain calcified structures, such that when
saturation state is less than 1, shells and other aragonite
structures can begin to dissolve. Calculating aragonite
saturation requires that, in addition to temperature and
salinity, at least two of the carbonate parameters (pC(}B
total alkalinity, DIC, pi I) be known. However, pCO, and
pH data from the sensors are not an ideal set of input
parameters for calculating aragonite saturation (i.e.
using the C02SYS software package) because they
carry the most uncertainty (Orr et al, 2018). Discrete
samples analyzed for dissolved inorganic carbon (DIC)
and/or alkalinity can be used in conjunction with pH and/
or pC02 to calculate aragonite saturation states and act
as validation data for the in situ sensors,
but many of the NEPs do not yet have the required
discrete data available to make these calculations
and therefore do not yet report time series of calcium
carbonate saturation states. Those NEPs that have
analyzed aragonite saturation have found that saturation
levels are lower in the summer and are influenced by
biological activity such as phytoplankton blooms and
by freshwater and oceanic (upwelling) inputs. Below
EPA summarizes the observations made by each of the
NEPs.
Measuring Coastal Acidification Using In Situ Sensors
In the National Estuary Program

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CASCO BAY
Observed Patterns in pH and pCO,
• Expected seasonality of pH. pC02, temperature, dissolved oxygen and salinity have been observed (Figures
3 and 4). The observations show that pH increases in the spring and decreases in the fall (Figure 5) and pCOj
decreases in the spring and increases in the fall (Figure 6).
20
s. 10
S	400
|	350
IS	300
|	250
I	200
o
1000
500






2016
2017
2018
2019
Figure 3. Observed seasonality of pC02, DO and tempurature observed. Casco Bay.
d)
TO
u_
CD
O
20
10
g 1000
O
500
8.0
ฃ 7.5
7.0

Itlli
M


2016
2017
2018
2019
Figure 4. Observed seasonality of pH, pC02 and temperature observed. Casco Bay.
Preliminary Monitoring Results

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8.0
7.5
Year
2015
2016
2017
2018
7.0
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Day of Year
Figure 5. Observed pH increases the spring and decreases in the fall. Casco Bay.
1000
1
CN
o
o
Q_
500
Year
•	2015
•	2016
•	2017
•	2018
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Day of Year
Figure 6. Observed pC02, decreases in the spring and increases in the fall. Casco Bay.
5
Preliminary Monitoring Results

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Relationship between carbonate parameters and other parameters
• Daily cycle in summer show influence of production, respiration and tidal exchange (Figure 7). In 2016, tidal
amplitude appears to influence pCOE. Lower tidal amplitudes result in higher pCO| in summer and fall. Water
is less well mixed during neap tides, and respiration will result in higher pCO? in bottom waters at our site.
Casco Bay (Figure 8).
B
N
o
<
12 46
11 63
10 80
ll111 11 11
1330 *
Sal
pCO, DO


t


665
599
532
466
|
<
Figure 7. Observed daily variability of pCO DO, and salinity (July 1-5).
1250
1
CNJ
o
o
Q.
1000
750
500
SO
0)
451
>
3
~a_
c
3Q-
CD
ฆpC02
ฆTides
Aug	Sep	Oct
Figure 8. Observed tidal amplitude and pH,pCO in 2016. Casco Bay.
Nov
Preliminary Monitoring Results

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Patterns in Aragonite Saturation
• In the first year (2015), aragonite saturation declined in July after a spring phytoplankton bloom (Figure 9).
Over several years, aragonite saturation (omega) was typically lower in the fall (Figure 10). The influence of
fresh water was detected. Saturation state influenced by rainfall and salinity. Precipitation brings in lower pi I
waters from watershed sources (Figure 11).
pH
3-
18.2
• I
J
mil:
ฃ V


> ) t
si
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Day of Year
Year
•	2015
•	2016
•	2017
•	2018
Figure 9, Aragonite Saturation State in 2015. Casco Bay.
Figure 10. Aragonite Saturation State 2015-2018. Casco Bay.
Daily Medians
03
G
ife?. >
hf".
' r-
Salinity
<26
26
27
28
•	29
•	30
•	31
•	32
NA
0	50	100	150
Precipitation (mm) Ten Previous Calendar Days
Figure 11. Observed aragonite saturation and precipitation. Casco Bay.
Preliminary Monitoring Results

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LONG ISLAND SOUND
Observed Patterns in pH and pCO,
•	A typical pattern of pl-l and pC02 observed in Long Island sound is shown in Figure 12 from the Western
Long Island Sound (WLIS) station. The pH variability in Long Island Sound is five to ten times larger than
the variability that occurs on the continental shelf. An inverse relationship between pM and pC02, where pH
decreases as pCOs increases can be observed, and is not unexpected as hydrogen ions are released as the
CO,, js dissolved and dissociates.
Relationship between carbonate parameters and other parameters
•	The rate of change of 02 in the bottom waters is consistent with pi I, because both are influenced by
respiration. However, because of the large inter-annual variation in temperature and salinity, it will take a
decade or two to see trends in the data.
WLIS Bottom pC02 - 2018
3000
2500
2000
H 1500
1000
500
04/01
05/01
06/01
07/01
08/01
09/01
10/01
11/01
12/01
Bottom pH WLIS and ARTG Stations - 2018
>.o 	'							
04/01	05/01	06/01	07/01	08/01	09/01	10/01	11/01	12/01
Figure 12. Time Series of pH and pC02 from the WLIS station in Long Island Sound, April through December 2018. Bottom pH
from ARTG is also shown, however the sensor failed and was removed in July.
Preliminary Monitoring Results

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BARNEGAT BAY
Observed Patterns in pH and pCO,
•	Data collected to date show a strong relationship between the pl-l and pCOz (Figure 13), as pC02 variability
explained 93% of the variation in pH. This indicates that legacy pH data collected in the area (e.g., J.C.
NERR station in Little Egg and New Jersey Department of Environmental Protection data) may be able to be
used to estimate pC02 and other carbonate parameters. This relationship will be explored further, when the
instrumentation is redeployed at the estuary.
Relationship between carbonate parameters and other parameters
•	DO and pH relationships are indicative of photosynthesis and respiration processes. Where these parameters
separate, other causes may be having an effect, such as freshwater input and upwelling.
•	The NEP will need data from multiple years to see trends and relationships. The NEP would like to collect
data over a couple of growing seasons to cover upwelling events more clearly (one upwelling event observed
to date).
Patterns in Aragonite Saturation
•	Limited data collection in Little Egg harbor did not indicate pH conditions of concern for bivalves, although
omega values can drop below 1 at night (see Figure 14).
Figure 13. Barnegat Bay-Relationship of pH and pC02
Figure 14, Barnegat Bay-Omega Aragonite in June and July 2017,
Preliminary Monitoring Results

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TAMPA BAY
Observed Patterns in pH and pCO, and other parameters
• The data (Yates et al. 2019) indicates evidence for tidal control on pl-l and pCOs on daily time scale
(Figure 15). In addition, the data shows evidence for temperature control over weekly to monthly time
scale (Figure 16).
*00 000* MM	00 ฉ~ K M	ซ0 4C 00 CO	00 0ฎ	0000	00 00
Ma Nปa Ml) tv+H NIB	Ml Jl	Nป JO	Mm 01	MvW
jim joio Mia nio *io jo io	aw joii	mo	joio	joto
IWil
E
Q.
Q.
JIM
M+0
•m *
Ml ]ป
JiM
OMM
JO-10
pm 7?
JO 10
• 10
Mia
J010
010
Figure 15. Tampa Bay-pH and pC02 at Middle Tampa Bay in February and March 2018.
Preliminary Monitoring Results

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. j month record
uiiml 	 I 1
|
1 ' ?
5
a
E
iiiunl:i iword
Figure 1 G.Tampa Bay-pH and pC02 and Temperature (December 2017 to March 2018).
COASTAL BEND BAYS
Observed Patterns in pH and pC02
•	High pl-l was observed for a majority of the monitoring period (Figure 17). During the approximately 10-month
monitoring period, significant temporal variations of both pC02 and pH were observed with a range of 251,2
to 619.7 micro atmosphere (palm) and 7.789 to 8.451, respectively.
•	Seasonal fluctuations and diel variability were observed. Higher pC02 and lower pH were observed during
summer and lower pCO and high pH were observed during winter. Diel variability was higher during the
summer months for pCO and during the winter months for pi I.
xj:	-
7 N.)	"5	ฆฆ
Jan	Afx	Jul
Month
E *ป-
ir	v vi^*' ฆ
ฃ
100
Jar	Afx	Jul
Month
Figure 17. Coastal Bend Bays-pH and pC02 data during the deployment period. The black data points represent hourly
measurements. Gaps between points occur when there were outliers due to various reasons.

Preliminary Monitoring Results

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Relationship between carbonate parameters and other parameters
•	Salinity and temperature both exerted controls on the variations of pCO., and pH at different extents,
indicating sensitivity of the estuarine water carbonate system to changes in both hydrological condition and
temperature. Carbonate alkalinity (OAlk) was calculated based on pCO. and pH data and was generally
higher in winter months and lower in summer months. C-Alk also showed an inverse relationship with salinity.
•	River discharge does not correlate well with salinity variability. There were no observed large pulses of
freshwater inflow during the time period to impact salinity or carbonate system. Salinity variability was likely
from local precipitation, evaporation, and tidal influence.
Patterns in Aragonite Saturation
•	Carbonate saturation state with respect to omega aragonite (QAr, the mineral for larval stage oysters) had a
mean of 4.50, but it did drop to undersaturation (minimum 0.91) for a short period of time. Nevertheless, QAr
was greater than 1 for 99.8% of the time, and greater than 2 for 95.9% of time, indicating overall optimal but
occasional sub-optimal condition in the Aransas Ship Channel, which serves as a conduit for the Mission-
Aransas Estuary and the Gulf coast (Figure 18).
14
12-
10-
5 H
CJ~ 8-
4 -
2-

Jtri	Aji	ป'jl
Month
'en 6CC0'
if 5CCO-
g 4COO-
- 3000"
~2COO-
< 1CCO*
jki* -"~
^	Jan	Apr	Jjl
Month
Figure 18. Coastal Bend Bays-Calculated saturation state of aragonite and carbonate alkalinity during the deployment
period. The black data points represent hourly measurements. Gaps between points occur when there were outliers due
to various reasons.
Preliminary Monitoring Results

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SANTA MONICA BAY
Observed Patterns in pH and pCO,
•	Year 1 deployment data show significant temporal variability in pH at the fixed depth of 15 m (Figure 19)
(LACSD, 2019). Significant temporal variability in pi I was also observed during the Year 2 deployment at
60 m. These time series suggest that vertical water movements at tidal to seasonal time scales are likely
responsible for much of the observed variability in pi I at the mooring.
•	pC02 values during the first period of the deployment were relatively constant, but during the spring upwelling
season (March through May), the pC02 levels rose considerably, and more high frequency variability was
observed (Figure 20) (LACSD, 2019). Relative to the shallower first year data, the Year 2 deployment at 60
m show less variability in the pC02 measured at this deeper depth. Levels are generally higher than those
observed during the first year, which was expected because this deeper location was consistently below
the pycnocline (the layer where the water density gradient is greatest). pC02 levels were highest during the
spring upwelling period.
8.2
8.0
x
a
7.8
7.6
pH First Year OAH mooring timeseries, CTD observations at 15m depth,
CLAEMD results
pH - SeapHOx
• CTD data - all sitesl5m
ฆ CTD data - adjacent sitel 5m
CLAEMD Discrete Results
Jul-16 Aug-16 Sep-16 Oct-16 Nov-16 Dec-16 Jan-17 Feb-17 Mar-17 Apr-17 May-17 Jun-17 Jul-17 Aug-17
Figure 19. Santa Monica Bay-First Year pH time series. CLAEMD results are adjusted for temperature and pressure.
pCOz First Year OAH mooring timeseries
1600
0
Jul-16 Aug-16 Sep-16 Oct-16 Nov-16 Dec-16 Jan-17 Feb-17 Mar-17 Apr-17 May-17 Jun-17 Jul-17 Aug-17
Figure 20. Santa Monica Bay-First Year pC02 Time Series.
Preliminary Monitoring Results

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Relationship between carbonate parameters and other parameters
• Consistent with expected oceanographic stratification, the pH and temperature correlate quite closely, pCOa
is roughly inversely correlated with temperature, pH and pCO? are inversely correlated, and oxygen and pH
are strongly correlated (LACSD, 2019). The relatively strong relationships between parameters suggest that it
may be possible to directly compute pH or pC02 using temperature, salinity, and oxygen. This could provide
a simple way to estimate Qarag and could be used to check and confirm that directly measured pH and pCO?
values were valid (Figure 21).
S&apHOx pH vs pCO;.
1 Sir sicTH P^iw Vsvdea i11/4,201&-'?'6>20'7)
R< = 0 8382
jao 4CC 600 ฃ00 IOjO 120C 143C
SeapHOx pH vs Temperature
15m depth utoTN Palos Vtenh* (11M/2016 7ฎ2017)

• I*
4—
^Polป 
R? = 0.80351
14 16 18 20
Tempeialurc (dug C)
24
Figure 21. Santa Monica Bay-Relationship of pH and pC02 (left) and pH and temperature (right) in Year 1
Preliminary Monitoring Results

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Patterns in Aragonite Saturation
• During the later period of the Year 1 deployment, and during the spring upwelling period, the aragonite
saturation level drops, and high frequency variability increases (Figure 22) (LACSD, 2019). Based on the
collected mooring data, the lowest aragonite saturation values occurred in the spring, and were likely due
to upwelling, which pushes colder water with lower plH and higher pCO„ towards the surface, thereby
decreasing aragonite saturation. Year 2 aragonite saturation levels were far less variable than the first year,
since the mooring at 60 m was below the pycnocline at all times. Lowest levels were seen during the spring
upwelling period (Figure 23). In all seasons, the aragonite saturation was generally above 1.7, and unlikely to
be a concern for shell building organisms. Biologically significant levels of saturation below 1.7 and 1.4 were
only observed during the spring upwelling periods and were almost never below 1.
Aragonite Saturation First Year OAH mooring timeseries
0
Jul-16 Aug-'6 Sflp-16 Oct-16 Nov-16 Dec-16 Jan-17 Feb-17 Msr-17 Apr-17 Mary-17 Jun-17 Jul-17 Aug-17
Figure 22. Santa Monica Bay-First Year Aragonite Saturation Time Series
Aragonite Saturation Second Year OAH mooring timeseries
5
4
C
o
ro
3 3
IB
(/>
0
Jari-18 Feb-18 Mar-18 Apr-18 May-18 Jun-18 Jul-18 Aug-18 Sep-18 Oct-18 Nov-18 Dec-18 Dec-18 Jan-19
Figure 23. Santa Monica Bay-Second Year Aragonite Saturation Time Series
Preliminary Monitoring Results

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SAN FRANCISCO ESTUARY
Observed Patterns in pH and pCO,
•	Ocean and watershed sources of high pC02 were observed, in addition, the ocean was identified as the
source for low DO (Figure 24).
•	Tidal correlation between salinity and pCO, was observed, but it shifts between positive correlation (e.g.,
February 2018) and negative correlation (e.g., March 2018) (Figure 25).
•	There is a clear signal of low pi I water coming in from the ocean. Signals of upwelling and land runoff
(freshwater) are seen in the data. Physical data are aligned with the working hypothesis that there is a
confluence of oceanic inputs with high freshwater runoff in the spring and influence of both runoff and ocean
water are seen in the data.
•	No true data interpretation has happened yet due to limited funding.
e
*o
ฉ
30
ป
boa Surfaca Salinity
ID
RTC cc: E j >y #
OtrtJt cปyrrซป/ of ป.TC
Figure 24. San Francisco Estuary-Ocean and watershed sources of high pCO.
SF Bay Sahmy and xC02 SW at Tiburon
401	r
660
">H—i—i—i—i—r
77 74 76
2018-Ffe 2018-feC
-i—|—\—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—r
76 07 04 cr> os 10 1? 14 16 18
2018-MW
-o- 543-Surface Samr,	xCO-.ซ Swats'
-e- sป8-Surtปcป Samty -ป-• xCO. Bf
Figure 25. San Francisco Estuary-Salinity-pC02 relationship
Preliminary Monitoring Results

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TILLAMOOK ESTUARY
Observed Patterns in pH and pCO.
•	Tillamook Estuary is just beginning to analyze aragonite saturation state data (Figure 26). To date, they have
observed that aragonite saturation is lowest during the summer indicating upwelling and coastal influence, as
well as during winter low salinity periods associated with freshwater inflow.
Relationship between carbonate parameters and other parameters
•	River surveys in the Tillamook watershed are being used to understand how seasonal changes in river end-
member chemistry impact estuarine carbonate chemistry.
•	They are used mixing models to distinguish watershed versus oceanic influences in the estuary (Figure 26).
Figure 26. Scatterplot of SeaFET pHT and Qarag (calculated with SeaFET pHT and salinity-derived alkalinity) at the Garibaldi Dock
mooring in Tillamook Estuary, OR from August 2017 to August 2019.
Salinity
30
25
20
15
7.6	7.8	8
SeaFET pHT
Preliminary Monitoring Results

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Next Steps
While these preliminary data provide important
baseline information necessary to elucidate trends
and the potential drivers of acidification, long-term
measurements are needed to clarify and confirm trends.
The inherent challenge of characterizing carbonate
chemistry in estuarine systems underscores the value
of continuous data and sustained monitoring programs.
EPA believes that sharing the methodologies and
lessons learned in this report will lead to information
sharing and technology transfer that will benefit the NEP
community and other coastal monitoring groups.
The NEPs identified in this report are at various stages
in their deployments, collecting discrete measurements,
analyzing their data, reporting, performing outreach,
seeking additional funding, and identifying opportunities
for collaboration. The NEPs are integrating their
preliminary results into actionable plans in several
ways including their Comprehensive Conservation and
Management Plans (CCMP), State of the Bay reports
and other opportunities in which stakeholders can work
together to access and use the data to inform future
monitoring efforts and other actions of the NEPs. Below
is a summary of next steps for coastal acidification
monitoring actions within the ten NEPs.
NEP	NEXT STEPS
EAST COAST
Submit the data to an on-line repository.
Publish the monitoring data in a peer review journal and include in the next State of the
Bay report.
The NEP will collaborate with the ocean acidification information exchange (OAIE) set
up by NECAN/NERACOOS and with the MOCA Partnership to share the data.
Casco Bay does not currently plan to continue this monitoring; however, a non-profit
partner, Friends of Casco Bay has established a water quality monitoring station and
is planning to have two additional stations operating by the end of the year, which will
include coastal acidification parameters, at different locations in the Bay.
MassBays	• As some challenges have been addressed, the system was deployed in spring 2020.
This was undertaken through a staged deployment. In January 2020, the pumping
system was installed and tested as to how it will hold up to cold temperatures, possible
icy conditions, storms, and wind. In June 2020, seawater was pumped through the
system for several hours to monitor the temperature, bubble, and flow conditions. The
system was tested for several months during which time a new thermosalinograph was
installed and technical improvements made to refine the system. The system will be
retested in situ in April 2021 and will be ready to start compiling data. Finally, telemetry
will be added in order to download data directly to UMass Boston. Train volunteers for
sample collection (Spring 2021).
•	Collect discrete samples to ground-truth data (bi-weekly samples starting June 2021).
•	Coordinate with Narragansett Lab to analyze water samples for TA and DIC (ongoing).
•	Develop outreach to share information with local communities on what the system seeks
to measure. Materials will be developed and a system to stream data online will be
developed.
•	Make data available to the Massachusetts Ocean Acidification Commission established
by the Massachusetts legislature in 2018, the Massachusetts Shellfish Initiative, the
shellfish industry, and other stakeholders.
Casco Bay	•

Measuring Coastal Acidification Using in Situ Sensors
in the National Estuary Program

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NEP
NEXT STEPS
Long Island Sound • Developing the budget to secure funding to make the system more reliable, integrate it
and sustain over the next two to three years.
•	There is a need to establish a program in all the estuaries to understand what the
variability in trends of pH and saturation concentrations are going to be.
Barnegat Bay	• Continue deployments and collect data during non-winter months.
•	Develop partnerships to collect discrete samples for comparisons/validations.
•	Work with other monitoring programs to develop a shared robust QA/QC procedure.
•	Identify an appropriate open-access repository for the data.
GULF OF MEXICO
Tampa Bay	• Migrate satellite telemetry system to University of South Florida system, because
the Southeast Coastal Ocean Observing Regional Association (SECOORA) and the
National Centers Environmental Information (NCEI) did not have graphing capability.
COMPS team updating website and add graphing capabilities.
•	Continue collaboration with Dr. Bob Weisberg and J. Law, USF to examine
hydrodynamic controls on water chemistry.
•	Synthesize data and compare trends and variability at Tampa Bay and Gulf of Mexico
monitoring locations.
Mobile Bay	• SeapHOX and SAMI-pC02 Instruments will be deployed in the field in fall 2021.
•	Monthly bay-wide discrete sampling program began in spring 2020 and will continue
through at least 2024.
•	Biogeochemical model is being developed for the Bay to understand drivers of coastal
acidification such as trends and variability in freshwater inflows, eutrophication, and
mixing with Gulf of Mexico waters.
Coastal Bend Bays • Since the pier was destroyed, seeking another site in productive waters to deploy the
system or wait for the research pier to be rebuilt.
• Continue discrete water collection.
Next Steps

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NEP
NEXT STEPS
WEST COAST
Santa Monica Bay • In early 2019, the Los Angeles Sanitation Districts received approval from the Los
Angeles Regional Water Quality Control Board for a new Special Study, which will
include continued use of the SMB/NEP sensors in coordination with a Wirewalker
mooring with a full CTD package, fluorescence sensors, and an on-board pH sensor.
This mooring will be deployed in Santa Monica Bay for a 12-month period beginning
in Spring 2021. The Wirewalker will allow the sensor array to measure vertical profiles
from the surface to 330 feet and transmit real-time data with a telemetry system (http://
delmarocean.com/wirewalker/).
•	The data from the Wirewalker will allow continued bay-scale assessment of causes
and dynamics of acidification: When and at what depths is acidification and hypoxia
occurring? What is the role of seasonal cycles, phytoplankton blooms, and other
local drivers on observed ocean acidification and hypoxia? Can any anthropogenic
associated local effect on ocean acidification and hypoxia be determined?
•	Support ongoing research to determine if local, nutrient-related sources (wastewater
discharges) to the Bay are contributing to ocean acidification (at ecologically significant
levels). Ultimately provide supporting data for any management actions.
•	Determine if coastal acidification can be ameliorated by increasing uptake via
restoration of submerged aquatic vegetation, which has been shown to have some
muted, but potentially significant, benefits in increasing pH, increasing DO, and
decreasing pC02. We are in the research stage and looking into growing giant kelp
forests and eelgrass offshore populations.
There is a lot that we still do not know about the carbonate chemistry of the San
Francisco Estuary. Our focus so far has been on the deeper main channel dynamics,
with an emphasis on understanding the characteristics of source waters arriving in the
Central SF Bay, and the processes delivering them.
We continue to work on identifying low-pH and low-oxygen events due to intrusion of
upwelled water from the ocean and assessing its impact through determining in-bay
modification and residence of these hypoxic intrusions.
We also continue to explore importance of freshwater inflow concurrent with intrusion of
low-pH, hypoxic ocean waters.
Next steps include a focus on the shallower areas outside of the main channel and
the role of biological processes, especially by submerged aquatic and intertidal
macrophytes and benthic algae, in driving biogeochemical changes in the less studied
shallow habitats of the estuary which support a diversity of ecologically important
species and functions.
There is a need to raise funding to sustain operations and conduct data analysis. We
are engaging with additional regional collaborators and stakeholders toward this end.
We look forward to collaborating with the NOAA Coastwide cruise in the future, as the
conditions of the pandemic allow, to conduct comparative, cross-calibration of samples.
San Fransisco
Estuary



Next Steps

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NEP
NEXT STEPS
Tillamook Estuary • Exploring estuary-scale assessment of causes and dynamics of acidification to inform
mitigation and adaption strategies: When and where are acidification and hypoxia
occurring? What is the role of local drivers versus ocean conditions on occurrence of
estuarine acidification and hypoxia? Developing approaches to identify anthropogenic
signals in acidification.
•	Tillamook Estuaries Partnership (TEP) and the Oregon Ocean Acidification and Hypoxia
Monitoring Workgroup received a $60,000 grant from the State of Oregon to purchase
three additional SeaFET and YSI instruments and conduct additional data collection
near oyster beds. This work will help build an ocean acidification monitoring network in
Oregon. Instrumentation for this expended two-year effort were deployed in July and
August of 2019. TEP has met with significant challenges with implementation of this
effort as identified in sections of this report. TEP will continues to refine its deployment
strategies to overcome obstacles and coordinate with research partners to produce and
disseminate results.
•	TEP received EPA funding to purchase and install a telemetry system in Tillamook Bay.
TEP will collaborate with EPA ORD staff to design and install the system, beginning in
spring 2021. In addition to allowing provision of real-time data to partners, the telemetry
system will allow TEP to seamlessly identify data abnormalities, biofouling, and
equipment failure, without significant interruption in data collection.
Next Steps

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