£2 CI 5A United States
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Environmental Protection Agency
NONINDIGENOUS SPECIES -
AN EMERGING ISSUE FOR THE EPA
Volume 2:
A LANDSCAPE IN TRANSITION:
EFFECTS OF INVASIVE SPECIES ON ECOSYSTEMS,
HUMAN HEALTH, AND EPA GOALS
Henry Lee II1
and
John W. Chapman2
May 2001
1 U.S. EPA, ORD/NHEERL
Western Ecology Division
2111 S.E. Marine Science Drive
Newport, OR 97365-5260, USA
2 Oregon State University, Department of Fisheries and Wildlife
Hatfield Marine Science Center,
Newport, OR 97365-5260, USA
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DISCLAIMER
The preparation of this document has been funded in part by the U.S. Environmental Protection
Agency under requisition number 10JN02 QT-DC-00-002171 from the Office of Science Policy
to John W. Chapman. The document has been subject to the Agency's peer review and
administrative review. It has been approved for publication as an EPA document. The statements
in this document do not necessarily reflect the views of the Agency and no official endorsement
should be inferred.
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TABLE OF CONTENTS
DISCLAIMER I
EXECUTIVE SUMMARY v
I. INTRODUCTION 1
II. IMPACTS ON ECOSYSTEM GOODS AND SERVICES 3
II-1. U.S. ECONOMY: 3
11-2. AGRICULTURE: 3
II-3. POLLINATION: 4
II-4. COMMERCIAL FISHING AND AQUACULTURE: 4
II-5. RECREATION - FISHING: 5
II-6. RECREATION - BOATING AND SWIMMING: 5
II-7. RECREATION - TOURISM: 6
II-8. MUNICIPAL. INDUSTRIAL AND AGRICULTURAL WATER SUPPLY: 6
II-9. FORESTS AND TIMBER PRODUCTION: 6
11-10. HYDROLOGIC AND SEDIMENT-TRANSPORT RELATED SERVICES: 7
10-A. Stream Flow and Water Table: 7
10-B. Runoff and Erosion: 7
10-C. Sediment Deposition: 8
10-D. Nutrient Fluxes: 8
11-11. POLLUTION SEQUESTRATION AND TRANSFORMATION: 9
11-12. FIRES: 9
11-13. CLIMATE CHANGE: 9
11-14. STRUCTURAL DAMAGE: 10
11-15. CULTURAL PRESERVATION: 10
III. IMPACTS ON HUMAN HEALTH 11
III-l. HUMAN HEALTH - DIRECT RISKS: 11
III-2. HUMAN HEALTH - PESTICIDE EXPOSURE: 12
IV. IMPACTS ON ECOLOGICAL CONDITION 13
IV-1. BIODIVERSITY: 13
IV-2. HAWAIIAN BIODIVERSITY: 14
IV-3. PRESERVATION OF NATIVE FLORA AND FAUNA IN PUBLIC LANDS: 15
IV-4. WILDLIFE: 15
IV-5. ECOSYSTEM SUSTAINABILITY: 16
IV-6. HYBRIDIZATION: 16
V. IMPACTS ON AGENCY GOALS AND POTENTIAL AGENCY ROLES 17
V-l. EXECUTIVE ORDER ON INVASIVE SPECIES: 17
V-2. AGENCY CREDIBILITY AND GPRA GOALS: 18
V-3. NEPA: 18
V-4. BlOCONTROL: 19
V-5. BALLAST WATER AND NPDES PERMITS: 19
V-6. TOTAL MAXIMUM DAILY LOADS: 21
V-7. WETLAND RESTORATION: 23
V-8. AMBIENT WATER QUALITY AND POLLUTANT DYNAMICS: 23
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V-9. DRINKING WATER QUALITY: 24
V-10. OPEN OCEAN DISPOSAL OF DREDGE MATERIAL: 24
V-l 1. INLAND DISPOSAL OF DREDGE MATERIAL: 25
V-12. ENDANGERED SPECIES ACT: 25
V-13. BlOCRITERIA: 25
V-14. MONITORING/RESEARCH PROGRAMS AND TAXONOMIC OA/OC: 26
V-l 5. ECOLOGICAL RISK ASSESSMENT: 27
V-l6. PESTICIDE USE AND POLLUTION PREVENTION 28
V-l7. PESTICIDE REGISTRATION: 28
V-18. SUPERFUND AND PHYTOREMEDIATION 29
V-l9. AIR QUALITY: 30
VI. RESEARCH NEEDS 31
VII. CONCLUSIONS 33
REFERENCES 35
APPENDICES 39
APPENDIX 1: ACTIONS IN THE INVASIVE SPECIES MANAGEMENT PLAN
RELATED TO THE EPA 41
APPENDIX 2: EFFECTS OF INVASIVE SPECIES ON ACHIEVING GPRA GOALS
AND OBJECTIVES 47
APPENDIX 3: INVASIVE SPECIES RESEARCH NEEDS 51
IV
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EXECUTIVE SUMMARY
Every day the United States is invaded by a host of nonindigenous species, also known as exotic,
introduced, alien, or non-native species. A portion of these nonindigenous species becomes
invasive species — the nonindigenous species resulting in ecological damage, human health
risks, or economic losses. To help identify the key scientific issues related to invasive species,
the EPA Regions and ORD held a series of Regional workshops followed by a National
Workshops series of Regional and National. These workshops are summarized in Volume 1 of
this report(U.S. EPA, 2001. Nonindigenous Species — An Emerging Issue for EPA. Volume 1.
Region/ORD Nonindigenous Species Workshop Reports). This document constitutes Volume 2
of the Nonindigenous Species — An Emerging Issue for EPA report. One goal of this document
is to provide an overview of the types of impacts invasive species have on ecosystem services,
human health, and economics. Another goal is to explore how invasive species can impact the
implementation of EPA's goals and mandates, and how EPA's regulations relate to the
management of invasive species. The major points are summarized below:
Extent of Invasion: Nearly every terrestrial, wetland, and aquatic ecosystem in the United States
has been invaded by nonindigenous species — one estimate puts the number of nonindigenous
species in United States at 50,000 species. These invasions are still occurring, and the invasion
rate is accelerating in some ecosystems.
Economic Costs: Invasive species are having a pronounced effect on the U.S. economy.
Agriculture is the most impacted ($71 billion/year). Costs to other segments of the economy,
including tourism, fisheries, and water supply, total $67 billion/year.
Ecological Services: Invasive species are degrading a suite of ecosystems services, including,
but not limited to: 1) agriculture; 2) forestry; 3) commercial and recreational fishing; 4)
frequency of fire; 5) flood control; 6) municipal, industrial, and agricultural water supply; 7)
boating and swimming; 8) climate change; and 9) culture preservation. Degradation of these
services results in direct economic losses, costs to replace the services, and control costs. While
more difficult to quantify, losses of these ecosystem functions also reduce the quality of life.
Pollutant Loadings and Dynamics: Terrestrial and wetland invasive species can dramatically
alter the loadings of nutrients, clean sediments, and toxic pollutants into surface and estuarine
waters. Invasive aquatic species, such as the zebra mussel, can alter the toxic effects and
bioaccumulation of contaminants by altering pollutant fate and dynamics within water bodies.
Biodiversity and Endangered Species: Invasive species are the second most important cause
for the listing of threatened and endangered species as well as being a major factor in the
regional and global declines in biodiversity. One consequence of this loss of biotic diversity is
the homogenization of the world's ecosystems. Another effect is the loss of ecosystem
sustainability.
Exotic Diseases: Introductions of exotic diseases, such as the West Nile virus, are related to the
breakdown of the same ecological, social, and economic barriers related to the introduction of
other nonindigenous species. A potentially important vector for the distribution of water-borne
pathogens, such as cholera, is the discharge of ballast water. Several of these exotic diseases
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have the potential of becoming serious regional or national public health threats, and their
number and geographical extent are likely to increase with global climate change.
Pesticide Use and Exposure: A major portion of all pesticides are targeted for exotic weeds,
insects, and mites. Presumably, a similar proportion of the ecological and human health effects
resulting from pesticides mirrors this usage pattern. The percentage of pesticides targeted for
exotic pests will increase with the continual introduction of new pests.
Executive Order on Invasive Species: An Executive Order on Invasive Species was authorized
in 1999. The Order created the National Invasive Species Council, an interagency council of
which the EPA is a member. The Invasive Species Management Plan, released in January 2001,
lists 57 action items, of which 21 relate to the EPA.
GPRA Goals: Invasive species potentially affect nine of the ten GPRA Goals, with Goal 2
(Clean and Safe Waters) being the most affected. Other GPRA Objectives potentially affected
include those relating to exposure to pesticides and persistent organic pollutants, remediation of
contaminated sites, climate change, and reduction of transboundary threats. Failure to account
for invasive species may result in non-attainment of certain GPRA Objectives.
Ballast Water Regulation: In January 1999, the EPA was petitioned to regulate all ballast water
discharges under NPDES. The Agency has not yet responded to the petition. Regardless of
EPA's decision, there is likely to be increased pressure to require mid-ocean ballast water
exchange, and most likely ballast water treatment.
Wetland and Superfund Remediations: Constructed or remediated wetland and upland
habitats are often invaded by invasive species, which can impair the reestablishment of desired
ecosystem functions. The remediated sites can also serve as "hot spots" for the invasion of
neighboring habitats. Legal issues regarding the extent to which Superfund sites have to be
returned to their native state and who is responsible need to be addressed. Use of exotic plants
for phytoremediation or erosion control is limited by the Executive Order, and to the extent
possible, native alternatives need to be found.
Total Maximum Daily Loads (TMDLs): All waters impaired by pollutants must be listed, and
States, Territories and authorized Tribes must establish TMDLs for these waters. Currently more
than one-third of all the States have waters that are listed for invasive species. EPA believes that
determination of whether a particular invasive species is a pollutant, requiring establishment of a
TMDL, requires a case-by-case analysis. In the future, the Agency may reevaluate whether
invasives such as noxious aquatic plants are pollutants for Clean Water Act purposes.
Additionally, by altering erosion, runoff, and deposition processes, terrestrial, wetland, and
aquatic invasive species can substantially alter pollutant loadings into surface and estuarine
waters. Failure to account for these effects in TMDL models could result in substantial errors in
calculating load allocations.
Role Of EPA in Managing Invasive Species: To date, EPA has had a relatively minor role in
the management of invasive species, in part because of uncertainty over the interpretation of
existing regulations. While legal and policy reviews are needed, possible roles for EPA include:
1) review of environmental impact statements under NEPA; 2) review of biocontrol agents under
NEPA; 3) ballast water management under NPDES; 4) evaluation of invasive species impacts
under ocean and inland dredge disposal regulations; 5) emergency registration of pesticides for
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invasive species under section 18 of FIFRA; 6) use of TMDLs on a case-by-case basis for waters
that are impaired by invasive species; 7) early detection through monitoring programs; and 8)
restoration of contaminated or disturbed habitats to native habitats under Superfund and other
restoration programs.
Research Role for EPA: With its experience in evaluating ecological condition and in risk
assessments, EPA brings unique skills to invasive species research. To focus the research, ORD
needs to work with the Program Offices and Regions to identify the highest priority needs.
Besides targeted invasive species research, much of the ongoing ecological research could
incorporate invasive species as a stressor at little additional cost.
Stakeholders/Politics: There is growing public and political concern over invasive species;
accordingly we anticipate there will be growing pressure from a suite of stakeholder groups for
the EPA to take a more active role in researching and managing invasive species. Even more so
than for pollutants, management of invasive species is complicated by opposing stakeholder
values regarding control measures (e.g., use of pesticides) and over the relative benefits or harm
of particular exotic species (e.g., exotic trout in western streams).
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I. INTRODUCTION
The ecosystems of the United States are being invaded by an unprecedented number of
nonindigenous species. Nonindigenous species, also referred to as exotic, introduced or non-
native species, are those species displaced from their historic range. Every major terrestrial,
wetland, and aquatic ecosystem in the United States has been invaded to some extent, and in
some habitats it is hard to find a native species. One estimate puts the total number of
nonindigenous species in the United States at 50,000 species (Pimentel et al., 2000;
http://www.news.Cornell.edu/releases/Jan99/species_costs.html), and the number is increasing
almost daily. Nonindigenous species invade through a wide variety of vectors - ballast water,
agricultural and horticulture shipments, packing material and pallets, releases from the pet and
live seafood trades, intentional releases by state agencies and the public, and as hitchhikers on
boats, planes, trains, and automobiles.
As a general rule, approximately 10 percent of exotic species will become "invasive" or
"nuisance" species, the nonindigenous species causing unacceptable ecological or economic
damage or threatening human health. According to the Office of Technology Assessment (OTA,
1993; http://www.wws.princeton.edu/cgi-bin/bvteserv.prl/~ota/diskl/1993/9325/9325.PDF)
about 15 percent of the 4500 nonindigenous species they evaluated caused severe harm, close to
the 10 percent rule. Based on the estimate of 50,000 nonindigenous species, the 10 percent rule
suggests that there are approximately 5000 invasive species causing severe harm in the country.
Some of these species are well known, such as the zebra mussel, kudzu vine, and many
agricultural pests. Others are less well known, and in many cases the ecological, human health,
and economic impacts of these species are only now beginning to be understood. There is also
the question of the cumulative impact of the other 90 percent of the nonindigenous species; en
masse —are they having deleterious ecological and economic effects that are not recognized on
an individual species level?
One goal of this report is to put these threats into perspective by providing examples of the
impacts from invasive species on ecosystem services, human health, and ecological condition.
Another goal is to evaluate how invasive species affect the implementation of Agency mandates
and goals. The last goal is to explore how existing environmental regulations relate to the
management of invasive species. This discussion expands upon possibilities brought up at the
National or Regional Nonindigenous Species Workshops and does not represent Agency policy
or a legal review of the regulations.
This report is a direct outcome of the ORD/Region Nonindigenous Species Workshop held in
Washington, DC on July 12 and 13, 2000. This national meeting was the culmination of a series
of five Regional Nonindigenous Species Workshops held across the country to help identify high
priority research needs related to nonindigenous species. Summaries of each of the Regional and
National workshops are presented in Volume 1 of this report (U.S. EPA, 2001). An additional
report was prepared for the Great Lakes (Glassner-Shwayder, 2000). Both the National and
Regional workshops were held as part of the Office of Science Policy's (ORD/OSP) "New
Directions" program.
In gathering data for this document we relied both upon the published literature and web
sources. In a rapidly evolving field like invasive species, web sources are often more up-to-date
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than the literature. In many cases, we give both the published and web sources, which allows
readers without access to technical libraries to review pertinent information. In some cases, we
used statistics directly from web sources, in which case the URL for the web page was cited. One
peril with web sources is that they may either change or be deleted. Nonetheless, we believe
web-based references will become an increasingly important mechanism to disseminate technical
and policy information.
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II. IMPACTS ON ECOSYSTEM GOODS AND SERVICES
Natural and managed ecosystems provide a number of goods and services that have direct
economic benefits (e.g., agriculture, fisheries) or direct social benefits (e.g., recreation). This
section provides examples of how nonindigenous species affect a variety of these goods and
services. Impacts on the intangible benefits of natural systems (e.g., biodiversity) are discussed
in "Section IV. Impacts on Ecological Condition".
II-l. U.S. Economy:
The full economic impacts of invasive species on the U.S. economy are only now beginning to
be fully appreciated. The Office of Technology Assessment (OTA, 1993) estimated that just 79
of the thousands of nonindigenous species caused $97 billion in cumulative economic damage
from 1906 to 1991. More recently, Pimentel and his colleagues (Pimentel et al. 2000;
http://www.news.Cornell.edu/releases/Jan99/species_costs.html) estimated the cost of invasive
species to the U.S. economy at $138 billion per year, representing a hidden "tax" of about $500
per year to each U.S. citizen. These dollar figures translate into very real regional and local
economic effects. A single weed, the leafy spurge (Euphorbia esula\ results in $87.3 million in
damage in North Dakota, the equivalent of about 1,000 jobs in a state with a population under 1
million (U.S. EPA, 2001).
Pimentel's analysis is the most comprehensive attempt at quantifying the economic
consequences of invasive species, and their estimates for various economic impacts are used in
this report in lieu of more specific figures. However, as impressive as these numbers are, they
may underestimate the true cost as their analysis include only the direct "losses and damages"
and "control costs" and not lost ecosystem services, such as water purification and aesthetic
values (see Daily et al. 2000 and http://esa.sdsc.edu/daily.htm for discussion of ecosystem
services). Moreover, the costs related to invasive species are increasing as nonindigenous species
continue to spread at accelerating rates.
II-2. Agriculture:
Invasive weeds, insects, and pathogens have an enormous impact on American agriculture.
Estimated costs from losses and control of exotic species are $27 billion/year for crop weeds,
$13.5 billion/year for crop pests (mostly insects), $21.5 billion/year for crop pathogens, and $9
billion/year for livestock diseases (Pimentel et al., 2000;
(http://www.news.Cornell.edu/releases/Jan99/species_costs.html). This totals $71 billion/year,
more than 50 percent of the estimated cost of invasive species in the United States. These
agricultural costs are likely to increase with invasions of new exotic weeds and pests, most of
which are likely to be "worse" than the existing pests
(http://www. forages. ess. orst.edu/Organizations/GLF/GLF 8. html). Moreover, these economic
losses do not include the economic or social costs associated with the human health impacts
resulting from pesticides used on invasive pests (see "V-16. Pesticide Use and Pollution
Prevention").
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II-3. Pollination:
The introduced European honeybee has been the dominant pollinator for a number of fruit and
vegetable crops (e.g., apples, cucumbers) worth about $10 billion dollars per year. However
since the 1980s, exotic varroa and tracheal mites have decimated honeybee populations — wild
populations have declined by about 90 percent and the number of cultured bee colonies has
decreased by about 50 percent. An additional threat is the Africanized or "killer" bee, which
either out competes or hybridizes with the European honeybee. Presumably, crop production will
decrease as a result of reduced pollination from wild bee populations and/or costs of maintaining
sufficient pollinators will increase. Additionally, beekeepers will suffer losses estimated at $29 -
$58 million per year (http://agnews.tamu.edu/bees/). This example, in which a beneficial
nonindigenous species is harmed by an invasive pest, illustrates some of the complexities
inherent in managing nonindigenous species.
II-4. Commercial Fishing and Aquaculture:
Invasive species can have major impacts on commercial fish and shellfish populations, even to
the point of the collapse of entire fisheries. An example is the American comb jelly, Mnemiopsus
leidyi, which was introduced into the Black and Azov Seas in the 1980s (Harbison and Volovik,
1993). Without major predators, the population of this jellyfish-like invertebrate exploded,
reducing native fish populations both by competing with larval fish for planktonic prey and by
feeding upon fish eggs and larvae. In less than a decade, the anchovy catch fell from about
500,000 to 100,000 tons. Mnemiopsus has spread into the Mediterranean potentially threatening
additional fisheries. Ominously, a basketball-sized Australian jellyfish, Phyllorhizapunctata,
recently invaded the Gulf of Mexico; in some areas this jellyfish was so common that a "person
could use them as stepping stones" (http://nas.er.usgs.gov/coelenterates/phyllorhiza.htm). It
remains to be seen whether this particular exotic species will have a measurable impact on Gulf
fisheries, but the Mnemiopsus example demonstrates that a single invasive predator/competitor
can devastate a fisheries.
Introduced diseases can also devastate fisheries, as with the eastern oyster Crassostrea
virginica that was a dominant species in eastern U.S. estuaries. Large scale oyster mortalities
associated with infections of the protozoan Haplosporidium nelsoni (MSX) were first observed in
Delaware Bay in 1957 (Haskin et al, 1966) and in the lower Chesapeake Bay in 1959 (Andrews,
1980). Within two years, more than 90 percent of the oysters in high salinity areas of the two bays
were killed (Andrews, 1980). DNA analyses indicate that//, nelsoni was introduced from California
or Asia and probably introduced with sanctioned plantings of the Japanese oyster C. gigas (Barber,
1997) or with ballast water. The continuing presence of Haplosporidia has prevented oyster recovery
in the lower Chesapeake Bay and has limited development of oyster aquaculture.
Besides diseases, harmful algal blooms (HABs) of toxic phytoplankton can render shellfish
unsafe for human consumption. The frequency and severity of HABs have increased both
nationally and internationally (http://www. cop. noaa. gov/pubs/das 10. html) and "seeding"of toxic
dinoflagellates through ballast water discharges is considered as one contributing cause. For
example, ballast water discharges are thought to cause toxic blooms of dinoflagellate
Gymnodinium catenatum that are responsible for the periodic closure of Australian shellfish beds
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(http ://www. environment, gov. au/marine/information/reports/somer/somer_annex 1 /som_ann8. html).
II-5. Recreation - Fishing:
As with commercial fisheries, invasive species impact recreational fish populations through
predation, competition, diseases, and habitat alteration. One especially destructive pathogen is
whirling disease (Myxobolus cerebralis). This pathogen was introduced into North America from
Europe in the 1950s and has spread through the western states, including Yellowstone National Park.
Whirling disease infects salmonids and is particularly damaging to rainbow trout; the rainbow trout
population in the upper Madison River has declined from 3,300 to 300 fish per mile (U.S. EPA,
2001). To avoid infections of whirling disease from river water, many hatcheries have implemented
extensive sterilization procedures and/or modifications to use groundwater. Despite spending $12
million since 1997 to upgrade state hatcheries, no stocked trout were released in Colorado in 2000
because of continued threat of infections (http://www. whirling-
disease.org/whirling/nostockco.html). As discussed in Section "V-6. TMDLs", under certain cases
hatcheries may be considered as point sources under an exotic disease TMDL.
An issue illustrating the conflicting views of different stakeholder groups towards
nonindigenous species is the controversy over stocking non-native fish. Stocked fishes constitute
a major portion of inland fishing in many states. Stocked fish account for 80 percent of the
freshwater fishing in Washington State and generate $725 million dollars
(http://www. nwr.noaa. gov/nnative/proceed/zook2.pdf). However, there is growing evidence that
stocked fish result in a number of adverse ecological effects. At an ecosystem level, "introduced
fish", many of which were stocked, impacted more highland stream miles than any other stressor
in EMAP's Mid-Atlantic Integrated Assessment (MAIA) survey
(http://www.epa.gov/emap/maia/html/rabrief/slidel4.html). At a population level, a well-
documented example is the decline in native trout populations due to predation by the introduced
brown trout (http://www.afsifs.vt.edu/afspos.html). As discussed in "Section V-15. Ecological
Risk Assessment", one of the complexities of managing nonindigenous species is that any
particular non-native species may have both desirable and undesirable characteristics.
II-6. Recreation - Boating and Swimming:
Boating and swimming are made virtually impossible in many lakes by thick mats of floating
(e.g., water hyacinth [Eichomia crassipes]) or rooted (e.g., Eurasian watermilfoil [Myriophyllum
spicatum]) aquatic weeds (see http://www.ecy.wa.gov/programs/wq/plants/weeds for description
of aquatic weeds). Decaying mats of these plants can also make beaches unusable.
Approximately $100 million is spent annually to control aquatic weeds in the United States
(Pimentel et al. 2000; (http://www.news.Cornell.edu/releases/Jan99/species_costs.html) and in
many cases, these programs are considered successful if they can simply "hold the line". Even
with an expenditure of $50 million during the 1980s, the percentage of Florida waters invaded by
hydrilla (Hydrilla verticillatd) increased from 37 percent to 41 percent
(http://www.ecy.wa.gov/programs/wq/plants/weeds/aqua001.html). Generally, aquatic weeds are
a greater problem in inland waters than in coastal areas, though dense strands of the invasive
smooth cord grass, Spartina altemiflora, limit recreational use of intertidal areas on the West
coast.
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II-7. Recreation - Tourism:
Invasions of non-native weeds can change the entire character of public lands. As reported in the
Governor's Idaho Weed Summit (http://www.blm.gov/weeds/BOISUMMI.WPD.htmn. the
Nature Conservancy's Altamount Prairie, South Dakota is no longer managed as a native prairie.
Even when invasives do not "take over" an ecosystem, they can reduce its recreational value.
Accessibility to park lands and trails can be limited by prickly weeds, such as yellow star thistle
(Centaurea solstitialis), while other invasives can reduce the populations of recreationally
important species, such as the impact of whirling disease on trout. A more subtle response is the
"emotional" or "spiritual" loss resulting from the degradation of native ecosystems. This societal
value is reflected in the National Park Service policy of actively managing exotic weeds, which it
considers "one of the most serious threats that parks face"
(http://wwwl.nature.nps.gov/wv/exotics.htm).
These reductions in recreational value translate into economic losses as tourists either go to
less invaded areas or find non-wilderness forms of recreation. For example, the leafy spurge
(Euphorbia esula) has resulted in a loss of $2.9 million dollars in recreational expenditures in
North Dakota alone (Wallace et al, 1992).
II-8. Municipal, Industrial and Agricultural Water Supply:
Aquatic nuisance species, in particular non-native bivalves and aquatic weeds, can disrupt
municipal, industrial, and agricultural water supplies. One of the main economic impacts of
zebra mussels (Dreissena polymorpha) is clogging the intakes for water treatment and power
plants. Left unchecked, zebra mussels can form mats up to eight inches thick. Another invasive
bivalve, the freshwater clam Corbicula fluminea, impedes water flow through irrigation channels
by forming shell reefs. The invasive Eurasian watermilfoil impacts power generation by clogging
intake pipes (http: //www. ecy. wa. gov/programs/wq/plants/weeds/aqua004. html) Estimates of the
costs to water infrastructure systems vary widely. Khalanski (1997 in Pimentel et al, 2000;
(http ://www.news. Cornell. edu/releases/Jan99/species_costs.html) estimated a cost of $5 billion per
year in damage and control by 2000 for zebra mussels. In comparison, a survey of facilities across
the country reported a cost of $69 million for zebra mussels (in Glassner-Shwayder, 2000).
Whatever the reasons for these differences, costs associated with the fouling of intake pipes
and irrigation channels are likely to increase as existing invasive species expand their
distribution and with the introduction of new aquatic nuisance species. An example of a new
threat is the Asian green mussel (Pema viridis) that was recently discovered in electrical utility
intake pipes in Tampa Bay (U.S. EPA, 2001). Another recent invader is the mitten crab
(Eriocheir sinensis) that has been spreading through San Francisco Bay into the Sacramento
River since the early 1990s (http://www.delta.dfg.ca.gov/mittencrab/life_hist.html). By
burrowing into stream banks, this Asiatic crab weakens the levees supplying water to
California's Central Valley agriculture while masses of migrating crabs clog fish diversion
screens.
II-9. Forests and Timber Production:
About 360 nonindigenous insect species are found in U.S. forests, of which a third are serious
pests (Liebold et al., 1995). The balsam wooly adelgid (Adelgespiceae\ one of The Nature
Conservancy's "Least Wanted" alien species (http://consci.tnc.org/library/pubs/dd/toc.html), has
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destroyed three-quarters of the spruce-fir forests in the southern Appalachians. Another
destructive pest is the gypsy moth (Lymantria dispar), which defoliates oaks and other
hardwoods in the Northeast. In total, invasive insects result in a $2.1 billion annual loss in timber
production (Pimentel et al 2000; http ://www.news. Cornell. edu/releases/Jan99/species_costs.html).
Forest associated losses are likely to increase substantially if the recently introduced Asian long-
horned beetle (Anoplophora glabripennis) becomes established. "Eventually it [Asian long-horn
beetle] could eat its way through the 42 million acres of forests from Maine to Minnesota that are
dominated by maple trees, forever changing the nation's landscape"
(http ://www.naplesnews. com/today/editorial/d3 0675 8a. htm).
Forests are also vulnerable to introduced pathogens, which result in an additional $2.1 billion
annual loss according to Pimentel. To date, the most damaging exotic disease has been the
Chestnut blight, which dramatically changed the landscape of eastern forests in the early 1900s.
11-10. Hydrologic and Sediment-Transport Related Services:
High densities of invasive weeds and animals can alter basic geological processes, including
runoff, erosion, sediment deposition, and groundwater recharge. In turn, these geological
changes can impact water quality, water availability, susceptibility to flooding, and sustainability
of wetland habitats. For clarity, the examples below are divided into different geological
processes; in reality, they are usually coupled.
10-A. Stream Flow and Water Table:
Excess transpiration by exotic weeds can reduce surface runoff, groundwater storage, and
wetland habitats. Salt cedar (Tamarix spp), a deep-rooted shrub common in riparian areas
throughout the arid west, consumes 10 to 20 times the water used by native species. With
its high water use, Tamarix can draw down the water table until streams and springs dry
up (http://www.earlham.edu/~biol/desert/invasive.htm). The Australian melaleuca
(Melaleuca quinquemervia) was intentionally dispersed to drain wetlands. Melaleuca
now threatens wetlands throughout Southern Florida, including hundreds of thousands of
acres in the Everglades (http://aquatl.ifas.ufl.edu/mcplnt2a.html).
10-B. Runoff and Erosion:
Erosion and runoff increases when native prairie grasses with fibrous root systems are
replaced with exotic weeds with taproots. For example, runoff increased by about 50
percent and sediment erosion doubled when native bunch grasses were replaced by
spotted knapweed (Centaurea maculosa) (Lacey et al., 1989;
(http://www.blm.gov/weeds/BOISUMMI.WPD.html). In turn, the increased erosion
resulted in higher stream temperatures and degraded fish habitat. Another study estimated
spotted knapweed increased soil erosion by 18 tons per 500 acres during a single
rainstorm (Duncan, 1997 in Westbrooks, 1998). By stripping the vegetation and rooting
in the soil, invasive animals, such as feral pigs, goats, and burrows, can also dramatically
increase erosion
Exotic plants can also reduce erosion, in particular by species that form dense covers or
with extensive root systems. In some cases, such as with kudzu vine (Pueraria montana
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var. lobata), non-native species that were deliberately introduced to stabilize the soil have
proven invasive. Non-native grasses are still frequently used in erosion control, though
there use will be limited under the Executive Order ("V-l. Executive Order on Invasive
Species"). Erosion can also be reduced indirectly when invasions of unpalatable weeds,
such as yellow star thistle, reduce grazing pressure on pastures and rangelands.
10-C. Sediment Deposition:
Dense stands of aquatic and wetland plants act as sediment traps and invasions of such
species can change the sediment dynamics in surface waters and estuaries. A freshwater
example is the giant reed, Arundo (Arundo donax\ which can reduce stream width and
depth, and in some cases impede stream navigation
(http://ceres. ca. gov//tadn/arundoWW.html). An estuarine example is the Atlantic smooth
cord grass (Spartina alterniflora) (http://www.willapabay.org/~coastal/nospartinaX which
has greatly enhanced sedimentation rates in invaded West coast estuaries. Without control
measures, such as aerial spraying of Rodeo, up to half of Willapa Bay's intertidal flats will
be converted to elevated Spartina salt marsh over the next 20 years (Wolf, 1993). This
conversion to elevated marsh is biologically equivalent to habitat loss from diking, and the
immediate impacts include loss of commercial oyster growing grounds and habitat for
migrating birds using the Pacific Flyway. Another concern is increased flooding resulting
from the reduction in water holding capacity in areas invaded by Spartina.
Invasive filter-feeding bivalves also enhance sedimentation in lakes (e.g., zebra mussels) and
estuaries (e.g., Potamocorbula amurensis) by actively stripping particles from the water
column and depositing them as feces or pseudofeces. A simulation study of Saginaw Bay
(Endicott et al, 1998) predicted that zebra mussels increased the flux of particles and
contaminants from the water column to the sediment by seven-fold. Zebra mussels have been
so effective at removing water-borne particles in some areas that they have noticeably
increased water clarity (see "V-8. Ambient Water Quality and Pollutant Dynamics").
10-D. Nutrient Fluxes:
Increases in runoff resulting from invasive weeds increase nutrient fluxes into surface and
estuarine waters. Presumably, the increases in nutrient inputs are directly related to the
increase in runoff and erosion, which as mentioned above can increase by 50 percent to
100 percent. Additionally, invasive weeds can alter nutrient processes within the soil. An
example is cheatgrass (Bromus tectorum). This innocuous looking grass introduced from
Eurasia to Washington in the 1890s quickly spread throughout arid areas of the west to
become a dominant grassland plant in Washington, Nevada, Utah, and Idaho. In
comparison to the native grasses, cheatgrass grows in thick blankets that shade out the
nitrogen-fixing microbiotic soil crusts, reducing nitrogen inputs. Other invasive weeds
increase soil nitrogen, such as the Atlantic shrub, Mycricafava, that has invaded the
nitrogen-poor volcanic soils of Hawaii. Mycrica, a nitrogen fixer, adds nitrogen 90 times
faster than the native flora, promoting invasion by other nonindigenous plants (Mack et
al., 2000; http://esa.sdsc.edu/issues5.htm).
In addition to terrestrial weeds altering nutrient loadings to water bodies, aquatic weeds
can change nutrient dynamics within water bodies. Decomposition of Eurasian
watermilfoil during the fall increases loadings of phosphorus and nitrogen to the water
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column (http://www.ecy.wa.gov/programs/wq/plants/weeds/aqua004.html). In the tidal
freshwater portions of Chesapeake Bay, Hydrilla verticillata sequesters nitrogen and
phosphorous in its tissues during the growing season
(http://Chesapeake.org/pubs/procs/stavstev.html). In the Susquehanna Flats Hydrilla was
a relatively minor component of the nutrient budget, but in the Potomac River Hydrilla
sequestered between 2.5 percent and 40 percent of the annual point-source inputs of
nitrogen and phosphorus during the summer growing season (Stevenson et al., 1989 in
(http: //Chesapeake. org/pubs/procs/stavste v. html). These nutrients are then released in the
autumn when the plants die back. Because nutrients are sequestered during the primary
growing season and released in the fall, it was suggested that Hydrilla might "function in
helping to suppress summer algal blooms and improving water quality."
11-11. Pollution Sequestration and Transformation:
Aquatic nuisance species can alter the sequestration (e.g., burial), degradation, and
transformation of toxic pollutants, and hence the bioavailability of these pollutants. Enhanced
sedimentation resulting from invasions of exotic wetland plants and filter-feeding bivalves ("II-
10. Hydrologic and Sediment-Transport Related Services") removes sediment-associated
contaminants from the water column and deposits them into the sediment. Deposition reduces
exposure to water-column organisms and promotes long-term burial of pollutants. However, by
concentrating the pollutants in the sediments, there is an increased likelihood of sediment
toxicity and/or bioaccumulation by the benthos and subsequent trophic transport to their
predators. Whether these biologically mediated processes increase or decrease toxic effects
depends upon site and pollutant characteristics. Aquatic nuisance species can also alter pollutant
bioavailability by altering trophic structure as discussed in section "V-8. Ambient Water Quality
and Pollutant Dynamics".
11-12. Fires:
Fire frequency and intensity increases when fire-adapted weeds replace native flora. In the lower
Colorado River flood plain, only 2 percent of the area with native flora burned between 1981 and
1992 versus 35 percent of the area invaded by salt cedar (Tamarix spp.) (Wiesenborn, 1996). The
frequency of fire in the rangeland in the Great Basin increased from once every 60-110 years to
every 3-5 years after the invasion of cheatgrass (Bromus tectorum) (Whisenant, 1990). Besides
the ecological impacts, the increased fire frequency threatens human life and property. This
threat is greatest in rural areas in the West, but even suburban areas can experience increased
risk. The proliferation of the exotic eucalyptus tree (Eucalyptus globulus) with its high resin
content contributed to the intensity of the 1991 Oakland, California fire that burned almost 3,000
dwellings (http://www.firewise.org/pubs/theOaklandBerkeleyHillsFire/).
11-13. Climate Change:
By reducing plant coverage and altering water cycles, overgrazing by domestic livestock, most
of which are exotic, can contribute to climate changes on a regional scale. The desertification of
Sub-Saharan Africa is the most dramatic example of such changes
(http://pubs.usgs.gov/gip/deserts/desertification). Another large-scale alteration is the burning of
substantial portions of the Amazonian forests and their replacement by African grasses (Mack et
al., 2000; and http://esa.sdsc.edu/issues5.htm). Conversion of tropical forests to grasslands
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sequesters less carbon and increases carbon dioxide inputs into the atmosphere. In addition to
these deliberate introductions, fundamental changes in plant communities due to invasive weeds,
such as is occurring over much of the arid West, may also change carbon dioxide inputs into the
atmosphere. Mack and his colleagues offer the following warning, "Our best estimate is that, left
unchecked, the current pace and extent of invasions will influence other agents of global change
— including the alteration of greenhouse gases in the atmosphere — in an unpredictable but
profound manner."
The converse is also true — alterations in global climate will influence invasive species.
Native ecosystems stressed by climate change are likely to be more susceptible to invasions.
Climate change is likely to have its greatest effect on promoting invasive species at the southern
and northern edges or boundaries of ecosystem types. Besides being more susceptible to
invasion, the increase in temperature will increase the number of sub-tropical and tropical
invaders. As mentioned below, this may include tropical diseases and disease vectors previously
rare in the continental United States (see "III-l. Human Health - Direct Risks").
11-14. Structural Damage:
The introduced Formosan termite (Coptotermes formosanus) represents a substantial threat to the
wooden buildings in nine southern states, California, and Hawaii
(http://www.ars.usda.gov/is/fullstop/). Besides consuming wood nine times faster than native
termites, the Formosan termite consumes live trees and can penetrate plaster and asphalt. This
single exotic pest costs about $1 billion per year in damage and control costs. In New Orleans this
single pest has caused more damage than hurricanes and floods combined over the last 10 years.
11-15. Cultural Preservation:
Invasive species threaten our cultural legacy. Historic buildings, for instance, are threatened by
exotic wood-boring pests; a speaker at the National Nonindigenous Species Workshop (U.S.
EPA, 2001) stated that the wooden buildings in New Orleans' French Quarter could "disappear"
in twenty years due to the Formosan termite. Formosan termites also infest a third of New
Orleans' historic live oaks. Underwater historical relics are also at risk. Zebra mussels threaten to
encrust historic sunken ships throughout the Northeast and Canada, including Benedict Arnold's
ship in Lake Champlain. In addition, zebra mussels produce an anaerobic microenvironment
promoting sulfur-reducing bacteria that disintegrate the iron spikes used in Revolutionary War
ship hulls.
Another type of cultural loss is the decline in native plants of cultural significance to Native
American Tribes. Many of these culturally important native plants decline due to the spread of
invasive plants such as spotted knapweed and sulfur cinquefoil (Potentilla recta)
(http://www.blm.gov/weeds/BOISUMMI.WPD.htmn.
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III. IMPACTS ON HUMAN HEALTH
Invasive species threaten human health as well as ecological and agricultural systems. One type
of health risk is direct, the introduction of exotic diseases. Introduction of these diseases results
from the breakdown of the same economic, ecological, and social barriers that allow the spread
of other nonindigenous species. In many cases, effective control of exotic diseases will require
an integration of invasion biology and the public health community, which to date have not been
well coordinated. The other type of risk is indirect, resulting from exposure to the pesticides used
to control exotic pests.
III-l. Human Health - Direct Risks:
The list of invasive pests and diseases posing a human health risk reads like a cast of characters
from a Steven King novel — fire ants, killer bees, brown tree snake, Brazilian pepper, West Nile
virus, Lyme disease, influenza, and acquired immunodeficiency syndrome (AIDS). Even
excluding AIDS, exotic diseases represent a national threat; under the correct conditions several
of these diseases have the potential to infect thousands of individuals. The increasing
globalization of the world increases the probability of the introduction of diseases previously
unknown in this country. The West Nile virus was first reported in New York in 1999 and has
since has been detected from Vermont to North Carolina, resulting in at least 18 deaths. Maps
displaying the spread of the West Nile virus can be found on the USGS National Atlas
(http ://nationalatlas. gov/natlas/natlasstart. asp). Since most of the exotic diseases are tropical,
global climate change is likely to result in a northward expansion of the areas at risk
(http://www.jrc.es/iptsreport/vol 13/english/Lif 1E136.htm and
http ://www. greenpeace. org/~climate/database/records/zgpz0749. html).
The dispersal of water-borne diseases through ballast water discharges is of particular
relevance to the EPA. In 1991, a Latin American epidemic strain of Vibrio cholerae was found in
the ballast water of a ship in Mobile, Alabama (McCarthy and Khambaty, 1994). A public health
advisory warning about the risks of eating raw seafood was issued when this strain was also
found in fish and shellfish (http://nas.er.usgs.gov/publications/ballast.htm). More recently, a
virulent Asian strain of Vibrioparahaemolyticus has been detected in U.S. coastal waters, raising
the possibility of ballast water transport (http://www.wisc.edu/fri/nonvibrio.htm). The World
Health Organization reported that ballast water discharge was the likely mechanism leading to
the "introduction of cholera for the first time this century into Latin America in 1991"
(http://www. who. int/inf-fs/en/fact 124.html). While further studies are needed to conclusively
establish the role of ballast water, the available evidence suggests that ballast water discharges
are an unregulated source of water-borne pathogens into coastal and estuarine waters. Also, as
mentioned above ("II-4. Commercial Fishing and Aquaculture"), ballast water discharges may
increase the incidence of harmful algal blooms (HAB), which can result in paralytic shellfish
poisoning (PSP) when contaminated shellfish are consumed.
By acting as disease vectors or hosts, exotic animals can promote the spread of both exotic and
native diseases. The Asian tiger mosquito (Aedes albopictus), introduced into Houston in 1985 and
now present in at least 26 states, is a potential vector for equine encephalitis, Dengue virus, and
yellow fever (http ://www. cdc. gov/ncidod/dvbid/arbor/albopic_new.htm). The Asian tiger mosquito
is more likely to spread these diseases than are native mosquitos because it attacks more hosts and
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bites during the day. The Asian mitten crab (Eriocheir sinensis) was banned from importation into
California in 1987 in part because it is a host for an Oriental lung fluke.
Besides diseases, several invasive pests, such as fire ants and poisonous plants, represent a
direct human health threat. These exotic pests can be important on a regional scale though they
do not pose the level of threat as the exotic diseases.
III-2. Human Health - Pesticide Exposure:
A substantial proportion of all pesticides used in agriculture are used to manage exotic weeds,
insects, and pathogens (see "V-16. Pesticide Use and Pollution Prevention"). Presumably, a
corresponding portion of all agricultural-related pesticide exposures and health risks result from
exposure to pesticides used to manage exotic pests.
A different social/political milieu is the use of pesticides in urban and suburban settings. In
1997 there was a public outcry after 1 million people were exposed to malathion in the Tampa
area in an effort to control the Medfly (Ceratitus capitatd). Substantial portions of New York
City and the outlying suburbs were subjected to aerial and ground spraying of malathion in 1999
with the discovery of the West Nile virus. Again, there was considerable public concern and
some environmental groups blamed the 1999 die-off of lobster in Long Island Sound on the
malathion (http://earthfiles.com/earthl 11 .htm). The West Nile virus was discovered again in
2000, and New York initiated a control program using Anvil, a pyrethroid-based pesticide. The
number of urban-suburban control programs is likely to increase with the continued introduction
of exotic diseases and vectors. These programs differ from agricultural programs in the number
of people exposed, greater potential for exposure of sensitive groups (e.g., children, asthmatics),
the public's low level of awareness about pesticide risks and how to minimize exposure, and a
lower acceptance of pesticide exposure than that in agricultural communities.
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IV. IMPACTS ON ECOLOGICAL CONDITION
The ecological attributes addressed in this section represent aesthetic, ethical, or spiritual values
to a substantial portion of the public (see Principe, 1995 for list of ecological values). For these
stakeholders, the ecological attributes are important in themselves and not for their market
benefits (e.g., ecotourism) or potential services (e.g., fire control). However, it is difficult to
quantify how much of a deviation from "reference" or "natural" conditions in these attributes is
acceptable. While the public supports "biodiversity" in principle, most people are unlikely to
care much about a reduction in the number of microbial species. In contrast, the public will react
vigorously to the extinction of a single species of songbird or marine mammal. It is beyond the
scope of this report to address the socio-cultural aspects of invasions other than to note that there
is a range in societal concerns regarding these ecological attributes. The public's specific
reaction depends on a suite of factors including whether "charismatic" species are impacted, the
number of species affected, size of the area impacted, and whether the nonindigenous species are
"desirable" to certain stakeholders.
IV-1. Biodiversity:
Alterations to biodiversity are perhaps the most fundamental ecological impact of invasive
species. A single invasive species can have devastating effects on local/regional species richness.
The Nile perch (Lates niloticus) was introduced into Lake Victoria, the world's largest tropical
lake, in!954 for fisheries development. Lake Victoria was home to 300 to 400 species of cichlid
fish species, about 5 percent of the world's freshwater species
(http://www.fao.org/waicent/faoinfo/fishery/statist/fisoft/dias/pape_nil.htm
http ://www. acts. or .ke). By the 1980's about half of these unique cichlid species were driven to
extinction due to predation by the Nile perch. The decline in the native algal-eating cichlids
allowed massive blooms of undesirable algae, collapse of local subsistence fishing, and increased
unemployment especially among women ("Report Of The Consultative Session On Lake
Victoria Fisheries" available at http://www.acts.or.ke). Yet even with these impacts there are
several stakeholders, in particular sports fishermen and fish exporters, who benefit from Nile
perch (http://www.fishingafrica.co.za/articlegb598.html).
In the United States, the relative impact of invasive species on biodiversity can be
ascertained from studies of the species listed under the Endangered Species Act. Wilcove et al
(1998; http ://www. fguardians. org/threats.html) concluded that 49 percent of the endangered or
imperiled species of plants and animals were threatened by invasive species, second only to
habitat loss. In an evaluation of 69 fish species listed under the Endangered Species Act, invasive
species were cited in 70 percent of the listings, again only second to habitat degradation (Lassuy,
1995, http://www.nwr.noaa.gov/nnative/proceed/lassuy 1 .pdf).
Changes in the total number of species on the earth can be considered the ultimate metric of
human impacts on ecological condition. Ominously, the modern species extinction rate is among
the greatest in the earth's history (Wilson, 1988; Pimm and Lawton, 1998), and invasive species
are one of the most important factors in this global loss of biological richness. In a study of
global vertebrate extinctions, Cox (1993; http://biology.usgs.gov/s+t/SNT/noframe/nsll2.htm)
found that invasive species were responsible for 109 extinctions compared to 73 resulting from
habitat disruption. Over the last 100 years, 3 percent of the 1,000 plus freshwater fish in the U.S.,
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Canada, and Mexico have gone extinct and another 26 percent are at risk
(http://www.sprl.umich.edu/GCL/notes2/introsp.pdf). The principal stressors on these freshwater
fish species are habitat destruction (73 percent) introduced species (68 percent), pollution (38
percent), hybridization (38 percent) and over harvesting (15 percent). Although hybridization is
categorized as an independent stressor in these figures, most hybridizations are due to human
introductions, suggesting that introduced species are the single most important stressor.
In addition to reducing the number of species, mixing of previously geographically isolated
ecosystems homogenizes the world's flora and fauna. Once biologically distinct regions and
ecosystems are becoming more and more similar, not unlike the effect the proliferation of fast-
food restaurants has had on homogenizing once distinct regional cuisines.
Under some conditions, exotic species increase species richness. Species richness increases
immediately after the introduction of an exotic. In most cases this is a temporary increase and
species richness will decline if the introduced species either dies out or, conversely becomes
invasive and impacts native species. In some cases, exotic species appear to be added to a
community without causing any obvious impacts. An example is an exotic seagrass, Zostera
japonica, in the Pacific Northwest. Z. japonica has a limited distribution within the estuary and
provides at least some of the same functions as provided by the native seagrass, Zostera marina,
such as food for Brant geese. While Z. japonica may be benign, the decade-long lag period
before the smooth cord grass, Spartina alterniflora, "exploded" to invasive densities in Willapa
Bay, Washington cautions against assuming a nonindigenous species will not result in ecological
havoc in the future.
IV-2. Hawaiian Biodiversity:
Because of the threats to its unique biota (http://biology .usgs.gov/s+t/SNT/noframe/pi 179.html
Hawaii deserves special mention. Island flora and fauna evolved in isolation from many stresses,
such as intense fires and browsing by large herbivores, making them especially vulnerable to
novel stresses (Jacobi and Scott, 1985; (https://128.174.5.51/demx/Public/ES-
Programs/Conservation/Invasive/hawaii.html). This contention is supported by Wilcove's et al.
(1998; http://www.fguardians.org/threats.html) conclusion that invasives are a greater threat to
Hawaiian species than those on the continental United States. Additionally, as hubs of global
transportation, islands are exposed to high rates of invasions. For example, an introduction rate
of 40 plant species per year over the last 200 years is required to account for the more than 8000
introduced plant species in Hawaii. Intentional introductions have also had major impacts; feral
pigs are the primary modifier of Hawaii's highland forests both by feeding on native plants and
by creating seed beds for exotic weeds (Westbrooks, 1998;
(http ://www. denix. osd. mil/denix/Public/ES-Programs/Conservation/Invasive/intro. html).
The combined effects of vulnerability and high invasion rates have devastated the Hawaiian
flora and fauna. At least 50 percent of the endemic birds and 90 percent of the native land snails
have been lost (http://biology.usgs.gov/s+t/SNT/noframe/c 102.htm) and Hawaii accounts for
almost 40 percent of all the plant species listed as endangered or threatened
(http://biology .usgs.gov/s+t/SNT/noframe/pi 179.htm).
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IV-3. Preservation of Native Flora and Fauna in Public Lands:
Another aspect of biodiversity is the preservation of the native flora and fauna on public lands.
This societal value is reflected in the proliferation of volunteer groups to eradicate invasive
weeds from public lands (e.g., TNC Weed Listserve attncinvasives@ucdavis.edu) and by the
high priority the National Park Service places on combating invasives. At least half of the 368
National Park System units have serious problems with exotic species
(http://www 1.nature.nps. gov/facts/ftexotic. htm) and they have concluded that "if exotics are not
actively and aggressively managed, the National Park System is at risk of losing a significant
portion of its biological resources" (http://www 1.nature.nps. gov/wv/exotics.htm).
IV-4. Wildlife:
Declines in charismatic birds, mammals, amphibians, and fishes are a major concern to the
public, and invasive species are a significant contributor to many of these declines. Reductions in
habitat quality resulting from invasions of purple loosestrife (Lythrum salicarid), Arundo,
Spartina alterniflora, and other exotic wetland species impacts a wide variety of wildlife species.
In terrestrial systems, native grazers avoid areas invaded by unpalatable species. Utilization by
deer, elk, and bison declined three to four fold in areas dominated by leafy spurge or spotted
knapweed (http://www.mtwow.org/FAQ.htm).
Exotic predators are an additional threat. Since its introduction into Guam in the 1950s,
predation by the brown tree snake (Boiga irregularis) has driven twelve native forest birds to
extinction and several others to the brink of extinction
(http://www.mesc.nbs.gov/research_briefs/bts/btreesnk.htm). The Indian mongoose (Herpestes
auropunctatus) was introduced into the Caribbean and Hawaii in the late 19 century to rid
sugarcane fields of rats. Instead, the mongoose preys mainly on native ground-nesting birds,
amphibians and reptiles. The mongoose is responsible for the extinctions of at least seven to
twelve birds, reptiles and amphibians in Puerto Rico and islands of the West Indies
(http://www.sciam.com/explorations/1999/021599animals/animals.html)
Less is known about the effects of introduced pathogens, but a poultry disease introduced
with domestic turkeys contributed to the demise of the last population of heath hens on Martha
Vineyard, Massachusetts in the 1930s. More recent threats are the West Nile virus, which infects
birds and various mammals (http://nationalatlas.gov/natlas/natlasstart.asp), and African
heartwater virus. The African heartwater virus, which can be introduced with ticks on imported
reptiles, represents a serious threat to North American bovine herds
(http://www.ruu.nl/tropical.ticks/nwl698i.htm).
The California clapper rail provides an example of how invasive species interact with other
types of stressors. The clapper rail population has been decimated by hunting, loss of its
marshland habitat, and contamination of its food sources. Additionally, the remaining clapper
rails fall are preyed upon by several non-native predators such as the red foxes, Norway rats, and
feral cats (http://hard.dst.ca.us/hayshore/library/esl l_95.htm). Moreover, rails feeding on the
introduced ribbed horse mussels (Geukensia demissa) can get their beaks or toes trapped when
the mussel closes. Trapped juvenile rails can drown on incoming tides (de Groot 1927), and in
the California Redwood marsh, as many as 29 percent of juveniles are lost to the ribbed mussel.
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The additional mortality resulting from invasive species makes it all the more problematical for
endangered populations to recover even when other anthropogenic stressors are mitigated.
IV-5. Ecosystem Sustainability:
In the absence of catastrophic events such as hurricanes, the public expects ecosystems to be
"sustainable" with minimal changes in species composition and valued ecosystem functions
(e.g., fishing). While this expectation is somewhat naive, the influx of invasive species is
changing ecosystems more drastically and much faster than would naturally occur. Dramatic
changes resulting from invasions of exotic species can often occur within a decade and are
noticeable even by casual observers.
A factor contributing to ecosystem instability is "invasional meltdown" where the
introduction of one nonindigenous species promotes the establishment of other introduced
species. An example presented at the National Nonindigenous Species Workshop (U.S. EPA,
2001) is that by increasing water clarity, zebra mussels create hard substrate suitable for the
invasive Eurasian watermilfoil (Myriophyllum spicatum). In turn, Eurasian watermilfoil provides
habitat for zebra mussels to settle on. An invasive tree in Hawaii, Myrica faya, fixes nitrogen,
creating a habitat suitable for the establishment of other invasive plants, which are better adapted
to higher nitrogen levels than the natives species (Mack et al, 2000;
(http://esa.sdsc.edu/issues5.htm). Myrica also attracts Japanese white-eye (Zosteropsjaponicus),
an invasive bird species that competes with native birds and disperses Myrica seeds. The net
effect of these positive feedbacks among invasive species is to accelerate the degradation of
native species and ecosystems.
IV-6. Hybridization:
Hybridization of native and introduced species or stocks was the sole or contributing cause to the
extinction of at least 3 of the 24 extinctions listed under the Endangered Species Act
(http://www.nap.edU/issues/13.4/schmit.htm). In the western states, the endangered Gila trout
and the Apache trout are currently threatened by hybridization with introduced rainbow trout.
Cross breeding with introduced mallard ducks threatens both the endangered Hawaiian duck and
the native Florida mottled duck. Both rainbow trout and mallard ducks were intentionally
stocked to enhance fishing and hunting, respectively, again illustrating the conflicting values
inherent in many invasive species issues.
The ability to predict whether hybridization will occur is problematic, as demonstrated by
Spartina alterniflora, which was introduced into Great Britain in ballast water. This Western
Atlantic marsh plant initially crossed with the native Spartina maritima to form a sterile hybrid,
Spartina townsendii. However, the sterile hybrid mutated into the fertile Spartina anglica which
has become the dominant cord grass in Great Britain
(http: //www j ncc.gov. uk/marine/dns/d2_l _5_1. htm).
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V. IMPACTS ON AGENCY GOALS AND POTENTIAL AGENCY
ROLES
This section evaluates how invasive species affect the ability of the Agency to achieve its
environmental goals and mandates as well as how various regulations could be applied to the
management of invasive species. The comments on the application of regulations arose from
discussions at the Regional and National Nonindigenous Species Workshops and do not
constitute Agency policy, policy recommendations, or a legal review of existing laws and
regulations.
V-l. Executive Order on Invasive Species:
Executive Order 13112 on Invasive Species was signed on February 3, 1999
(http ://www. invasivespecies. gov). This Executive Order calls for federal agencies to use relevant
programs and authorities to:
1) Prevent the introduction of invasive species
2) Detect and respond rapidly to and control populations of such species in a
cost-effective and environmentally sound manner
3) Monitor invasive species populations accurately and reliably
4) Provide for restoration of native species and habitat conditions in ecosystems that
have been invaded
5) Conduct research on invasive species and develop technologies to prevent
introduction and provide for environmentally sound control of invasive species
6) Promote public education on invasive species and the means to address them.
Additionally, the Order states that federal agencies shall "not authorize, fund, or carry out
actions that it believes are likely to cause or promote the introduction or spread of invasive species
... [unless] the agency has determined and made public its determination that the benefits of such
actions clearly outweigh the potential harm caused by invasive species; and that all feasible and
prudent measures to minimize risk of harm will be taken in conjunction with the actions."
The Executive Order establishes an Invasive Species Council co-chaired by the Secretaries of
Interior, Agriculture, and Commerce. Within EPA, a charter member of the Council, the
Assistant Administrator for the Office of Research and Development (ORD) is the "principal
representative" while Mike Slimak (ORD/National Center for Environmental Assessment
(NCEA)) is the Agency representative on the Council. An informal Agency group, the
Nonindigenous Species Workgroup (NISWG), composed of representatives from the Program
Offices, Regions, and ORD has been used to help coordinate the Agency's response to the
Council (contact: Henry Lee II, lee.henry@epa.gov).
The Council has prepared a National Invasive Species Management Plan that is to be the
"blueprint for coordinated Federal action". The final version of the Plan was released on January
18, 2001 and is available at http://www.invasivespecies.gov. The Plan lays out action items for
federal agencies, including specific actions targeting the EPA as a lead agency as well as other
actions where the EPA could have a role. These recommended actions could significantly affect
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the Agency, in particular the Office of Water, Office of Prevention, Pesticides, and Toxic
Substances, Office of International Affairs, and Office of Research and Development. Appendix
1 lists the specific action items potentially affecting the EPA; our analysis suggests that 21 of the
57 action items relate to the EPA to some degree. Appendix 1 also presents a preliminary
interpretation as to the effects of the action items on the EPA.
V-2. Agency Credibility and GPRA Goals:
The EPA has historically focused on pollutants, even though EPA's mission statement is much
broader, and includes a goal that "Environmental protection contributes to making our
communities and ecosystems diverse, sustainable and economically productive"
(http://www.epa.gov/history/org/origins/mission.htm). As described in this document, invasive
species are one of the major anthropogenic stressors degrading the diversity, sustainability, and
economic productivity of our Nation's ecosystems. The public views the EPA as the protector of
the environment, and one conclusion to come out of all the Regional Nonindigenous Species
Workshops was that the EPA should take a greater role in managing invasive species. Another
concern raised at the Regional Workshops was that the failure to address an obvious high priority
risk undermines EPA's commitment to the risk assessment approach. Failure to address invasive
species while focusing on less important stressors may taint the Agency with "the operation was
a success but the patient died" reputation.
Besides credibility with the public, the Agency's political credibility will suffer if it fails to
achieve its Government Performance Results Act (GPRA) Goals and Objectives as a result of
invasive species. Because they affect such a wide range of ecological processes, invasive species
potentially affect nearly every GPRA Objective that includes an ecosystem endpoint or a
terrestrial-aquatic flux. Appendix 2 presents our analysis of the impacts on GPRA Goals and
Objectives. Appendix 2 should be used as a starting point, and Program Offices and Regions
should conduct their own analysis. Nonetheless, it is apparent that invasive species are likely to
affect the implementation and success of a number of GPRA Objectives across a suite of
programs and media.
V-3. NEPA:
The National Environmental Policy Act (NEPA) requires environmental assessments (EAs) and
environmental impacts statements (EISs) for all federal actions that might impact the
environment. Under NEPA, EPA has broad review responsibilities that have been delegated to
the Regions and the Office of Federal Activities. Nonindigenous species potentially affect the
Agency's reviews in at least four ways. 1) The reviews should evaluate whether the proposed
actions will promote the introduction and/or spread of nonindigenous species. Addressing these
types of effects will require evaluation of ecological processes not normally included in most
EAs and EISs, such as whether the proposed actions will create habitats prone to invasions. 2)
The reviews should evaluate whether invasive species have reduced the "assimilative capacity"
of the native species to such an extent that more protective limits are required on other
anthropogenic stressors. 3) The Invasive Species Council in cooperation with the President's
Council on Environmental Quality (CEQ) is developing guidance on the use of NEPA in
managing invasive species by August 2001. Presumably, the Agency's role in reviewing EAs
and EISs addressing invasive species would increase if NEPA is promoted as an omnibus
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regulatory tool for invasive species. 4) The fourth role is the review of biocontrol agents, which
is discussed below.
V-4. Biocontrol:
Biocontrol is the release of host-specific predators or pathogens to control invasive species
populations. There have been some historical disasters resulting from such releases (e.g., rabbits
in Australia, mongoose in Caribbean), and there remains a real risk even when potential
biocontrol agents undergo more rigorous host-specificity tests. An Eurasian weevil released to
control musk thistle is now attacking native thistles, including an endangered species
(http://esa.sdsc.edu/issues5.htm). Even with these concerns, biocontrol is one of the few
management tools available once a nonindigenous species become invasive, and the Invasive
Species Management Plan (see "V-l. Executive Order on Invasive Species") promotes its use.
Therefore, the use of biocontrols is likely to increase in both agricultural and non-agricultural
settings.
Under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), EPA regulates the
release of microorganisms and viruses used for biocontrol. The Agency has a review role with
larger organisms (e.g., insects) used for biocontrol. According to the USD A
(http://www. aphis. usda. gov/nbci/nbci.html X there "are two bases for the regulation of biological
control organisms — either along with plant pests under [USDA's] APHIS' FPPA-based
authority, or along with pesticides under EPA's FIFRA-based authority - neither of which suits
the actual nature and scope of biological control." (FPPA is the Federal Plant Pest Act that
regulates the release of organisms "which can directly or indirectly injure or cause disease or
damage in any plants".) The USDA has a Technical Advisory Group (TAG) to review biocontrol
permits (http: //www. aphis .usda. gov/ppq/ss/tag/ X on which there is one EPA representative.
Based on our preliminary evaluation of the process, it is unclear whether the EPA has the
authority to take a more active role in the evaluation of biocontrols under its NEPA authority
and, if so, what role it should take.
V-5. Ballast Water and NPDES Permits:
By taking on and then discharging ballast water, ships transport massive quantities of water,
estimated at more than 21 billion gallons/year discharged into United States waters
(http://courses.Washington.edu/sma55Oo/BWpetitn.html). This is equivalent to a 58 MGD
discharge. These discharges inoculate coastal and inland waters with a plethora of exotic
organisms, and ballast water discharges are estimated to have resulted in the introduction of
more than 40 species into the Great Lakes and 50 into San Francisco Bay in the last 30-40 years
(NRC, 1996; http://www.nap.edu/books/0309055377/html/mdex.htmn.
Spurred on by the ecological and economic impacts of zebra mussels in the Great Lakes, the
Nonindigenous Aquatic Nuisance Prevention and Control Act (NANPCA) was passed in 1990,
requiring ballast water exchange or equivalent treatment for all ships entering the Great Lakes
from outside the Exclusive Economic Zone (EEZ). In recognition of the risks to other water
bodies, the National Invasive Species Act (NISA) was passed in 1996 (modified in 1999). NISA
requires mandatory mid-ocean ballast water exchange or equivalent treatment for ships entering
the Great Lakes and parts of the Hudson River from outside the EEZ. It also establishes a
voluntary ballast water exchange program with mandatory reporting for all ships entering U.S.
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waters from outside the EEZ (http://invasions.si.edu/ballast.htm and
http://www.nemw.org/biopollute.htm).
Within 24-30 months of its implementation in July 1999, the Coast Guard is to report to
Congress on the effectiveness of the voluntary approach and whether a mandatory ballast water
exchange is needed. The first year's results indicate poor compliance with only 21 percent of the
ships filing the mandatory report (http://invasions.si.edu/NABSlstAnnualReport.pdf). Of the
ships that voluntarily exchanged ballast water, 79 percent of them conducted only a partial
exchange of their ballast, leaving the potential for the introduction of exotic species. The current
voluntary exchange program is administered by the Coast Guard with the Smithsonian
Environmental Research Center (SERC) serving as the clearinghouse; the EPA is only
incidentally involved.
In contrast to MSA, the EPA is directly involved with ballast water management under the
Uniform National Discharge Standards for Armed Forces Vessels Act (UNDSAF), which
amended the Clean Water Act (CWA) in 1996. Under UNDSAF, the EPA is working with the
Armed Forces to establish a single set of national pollution guidelines for all Navy ships which
will likely include mid-ocean ballast water exchange.
A potentially greater role for EPA is the regulation of ballast water discharges under the
NPDES permitting process. In January 1999, a group of fifteen environmental, fishing, and water
supply groups petitioned the EPA to repeal a regulatory exclusion exempting the discharge of
ballast water from point-source permitting requirements
(http://courses.Washington. edu/sma5 5Oo/BWpetitn. html). The petitioners argued that the EPA
does not have the authority to exclude "discharge[s] incidental to the normal operation of a
vessel" (e.g., ballast water, bilge water). As noted by the petitioners, repealing this exclusion
would result in "paving the way for the regulation of ballast water discharges under the CWA."
The EPA did not release a final response to the petition so that "In January 2001, the groups
informed EPA that legal recourse would be necessary if the petition was not answered. EPA
responded on February 7 by telling the groups about its involvement in various committees that
are attempting to address the exotic species problem. The agency declined to give the
organizations a date by which it would respond to their petition." (see "News/Media" at
http://www. northwestenvironmentaladvocates. org). Then in April 2001, a lawsuit was filed
against the EPA in the federal district court in San Francisco alleging that "the EPA has violated
the Administrative Practices Act by failing to respond to the petition."
Regardless of EPA's response to the petition and lawsuit, the decision is likely to be
challenged either by the shipping industry and ports or by environmental groups and their allies.
While there is opposition from the shipping industry to regulating ballast water under NPDES,
representatives from the shipping industry stated at the Region 4 Nonindigenous Species
Workshop (U.S. 1999a) that they would prefer a "practical" national or international regulation
than a patchwork of state regulations like those recently promulgated in California and
Washington, and being considered in Oregon (for summary of state laws see http://ballast-
outreach-ucsgep.ucdavis.edu).
Even as the debate over ballast water exchange continues, there is a growing consensus that
mid-ocean ballast water exchange is not sufficiently protective because of incomplete exchange
of ballast water and organisms living in the sediments or on the walls of ballast tanks. Most
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experts now believe some type of ballast water treatment will be required to sufficiently lessen
the risk of new introductions. Treatment could either be on-board or dockside. Techniques under
consideration include filtration, centrifugation, biocides, heat, UV radiation, and discharge of
ballast water into sewage systems. The two primary biocides being evaluated are oxidizing
biocides, in particular chlorine and ozone, and nonoxidizing biocides, in particular
glutaraldehyde. Presumably, the EPA would permit any effluent discharged from these
treatments, especially if biocides were used. Another potential role for EPA is in the validation
of these treatment systems through the Environmental Technology Verification (ETV) program
or at the ORD laboratories.
V-6. Total Maximum Daily Loads:
Under Section 303(d) of the Clean Water Act (CWA), States, Territories and authorized Tribes
must identify impaired and threatened waters every two years. Impaired waters are those that do
not meet applicable water quality standards even after controlling point sources of pollution.
Threatened waters are those that currently meet water quality standards, but for which adverse
declining trends indicate that standards will be exceeded by the next 303(d) listing cycle. States,
Territories and authorized Tribes are required to establish priority rankings for impaired waters and
develop TMDLs for these waters. A TMDL specifies the maximum amount of a pollutant that a
waterbody can receive and still meet water quality standards, and allocates pollutant loadings
among point and nonpoint pollutant sources. EPA must approve or disapprove lists and TMDLs
established by States, Territories and authorized Tribes. Invasive species potentially relate to
TMDLs in three ways: 1) TMDL listings for invasive species, 2) use of TMDLs to indirectly
manage exotic species, and 3) affects of exotic species, especially weeds, on pollutant loadings.
Approximately 900 waters in 19 States are listed for invasive species on the 1998 303(d) list.
The majority of these noxious aquatic plants are affecting lakes, many of which are also impaired
by nutrients. Current regulations require that TMDLs be established only for pollutants. Since
the CWA includes "biological materials" in its definition of "pollutant", and since one of the
primary objectives of the Clean Water Act is the restoration and maintenance of biological
integrity of the Nation's waters, an invasive species may be a "pollutant" for CWA purposes in
some circumstances. In 1978, EPA decided that all pollutants, under proper technical conditions
are suitable for the calculation of TMDLs. EPA believes that determination of whether a
particular invasive species is a pollutant requires a case-by-case analysis. In the future, EPA may
reevaluate whether materials such as "noxious aquatic plants" are pollutants, generally or in
individual situations, for Clean Water Act purposes.
One recent case has been for noxious aquatic plants affecting two Louisiana lakes. Under the
terms of a recent partial consent decree in Louisiana, and based on the strong correlation between
reduction of nutrients and reduction of noxious aquatic plant growth, EPA established a nutrient
and noxious aquatic plant TMDL for two lakes in Louisiana (December 22, 2000). In this
particular case, EPA considered the noxious aquatic plant growth in Chicot Lake and Lake
Cocodrie to be a "pollutant" within the meaning of Section 502(6) of the Clean Water Act.
A second case under consideration is a draft Exotic Species TMDL for San Francisco Bay,
California, completed by the San Francisco Regional Water Quality Control Board, State of
California, for EPA Region IX (May 8, 2000 http://www.swrcb.ca.gov/rwqcb2/Tmdl.pdf). San
Francisco Bay waters are listed on the 1998 303(d) list as impaired by exotics, and are ranked as
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high priority for TMDL development. The major source of exotic species introductions to the
Bay is via ships' ballast water. While EPA has not taken the position that exotic species in ballast
water qualify as pollutants, or made any determination about the suitability of TMDLs for exotic
species in ballast water, EPA has stated its strong support for the State's emphasis on protecting
the Bay ecosystem from the effects of exotic species. In this draft TMDL, ballast water
discharges are identified as the primary source of new introductions, and the loading for new
exotic species is set at zero. No action is proposed regarding the existing exotic species under the
draft TMDL. Implementation of the San Francisco Bay draft TMDL is phased, and the first stage
is to use the best practical technology (BPT), which was determined to be mid-ocean ballast
water exchange. However, since ballast water exchange alone would not achieve the loading
requirement, the draft TMDL anticipates that some type of ballast water treatment would be
required in latter phases of the draft TMDL implementation. This draft TMDL has not been
approved by the State, and therefore has not been submitted to EPA for approval.
Prior to the completion of the draft San Francisco Bay TMDL, California passed state law
AB 703 (October 10, 1999) which requires mandatory mid-ocean ballast water exchange,
essentially equivalent to the requirement for the Great Lakes under NISA (see "V-5. Ballast
Water and NPDES Permits"). While California state law AB 703 implemented the BPT phase of
the draft TMDL, it also prohibits the Regional Boards from issuing either less or more stringent
requirements (e.g., ballast water treatment) until the law "sunsets" in January 2004. Because the
technologies for ballast water treatment are only now being developed and verified, the delay in
requiring ballast water treatment is not considered a major limitation to the phased
implementation of the draft TMDL.
Theoretically, TMDLs could also be used to indirectly manage existing invasive species (vs.
new introductions as in San Francisco Bay draft TMDL) by controlling the loadings of pollutants
that promote exotic species. For example, tubifex worms, the intermediate hosts of whirling
disease (see "II-5. Recreation - Fishing"), are abundant in organically enriched sediments.
Reducing loadings of fine sediments and organic matter could limit their population, which in
turn could reduce the incidence of whirling disease.
Finally, invasive species can indirectly affect TMDL development by altering loadings of
conventional and toxic pollutants. The particular effects will depend upon the nature of the
pollutant, ecosystem, and invasive species. By increasing erosion, terrestrial weeds in the arid
west may double the loadings of clean sediments and pollutants into surface waters (see "II-10.
Hydrologic and Sediment-Transport Related Services"). Depending on the species, terrestrial
weeds can either increase or decrease soil nitrogen (see "10-D. Nutrient Fluxes"), which
presumably would affect loadings from runoff. In some water bodies, aquatic weeds store and
then release substantial amounts of nutrients, which will affect both seasonal changes in nutrient
loadings and their ecological impacts (see "10-D. Nutrient Fluxes"). Failure to account for these
biologically mediated transport processes can introduce considerable error in the predictions of
background or "natural" loadings, and hence the allowable loadings from point and non-point
sources.
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V-7. Wetland Restoration:
Estimates put the loss of existing wetlands at 70,000 - 90,000 acres per year
(http://www. epa. gov/OWOW/wetlands/vital/status. html). To counter this trend, the Agency has a
goal of "a net increase of 100,000 acres of wetlands" per year by 2005 (GPRA Goal 2, Objective
2, Subobjective 2.2; see Appendix 2). In achieving this goal, one thrust should be to stop or slow
the loss of existing wetlands. The problem is that invasive wetland plants, such as purple
loosestrife, are invading and fundamentally altering thousands of acres of wetlands. These
invasions result in the loss of key wetland functions, such as bird habitat, if not the actual loss of
wetlands per se.
The impact of these invasions on achieving the Agency's GPRA Goal depends upon whether
the acreage of wetlands is determined by the acreage of functional, native wetlands or by the
presence of any wetland plant species regardless of how undesirable. Although the definition of
wetlands is a contentious policy and legal decision, we believe including highly altered wetlands
as part of the 100,000 acres is a temporary fix that obscures the more basic problem of the net
loss of wetland functions. Long-term ecological, political, and economic interests would best be
served if the GPRA Goal is achieved by an annual increase of native wetlands.
The second element in achieving this GPRA Goal is to restore or create new wetlands. The
importance of using native species in restoration is now recognized as one of EPA's principles in
restoring aquatic resources (http://www. epa. gov/owow/wetlands/restore/principles. html#3 X and
is required by the Executive Order unless there are compelling reasons to use non-native species
(see "V-l. Executive Order on Invasive Species"). A thornier problem is that newly constructed
or restored wetlands are "disturbed" habitats and as such are vulnerable to invasions.
Establishment of exotic weeds in these constructed wetlands could serve as a seed source for
invasions of neighboring wetlands. This concern was raised at the wetland/riparian session of the
Region 9 Nonindigenous Species Workshop, where several wetland experts recommended that
no new wetlands be constructed in San Francisco Bay until it can be demonstrated that the new
sites will not be overtaken by invasives, in particular Spartina altemiflora.
The possibility of "restored" wetlands infecting neighboring native habitats raises questions
about the ecological validity of wetland mitigation banks. It is critical, therefore, to develop and
validate restoration techniques for native species for various wetland types. Potential approaches
include both restoration techniques (e.g., timing of restoration, planting rapidly growing
"restoration" species to minimize initial invasions, better replication of microhabitats) and
control techniques (e.g., removal of nearby invasives, use of selective herbicides).
V-8. Ambient Water Quality and Pollutant Dynamics:
Invasive species can degrade water quality both by increasing loadings and by altering pollutant
dynamics within water bodies. Some of the primary mechanisms (see "II-10. Hydrologic and
Sediment-Transport Related Services") include: 1) decreased stream flow; 2) increased erosion
and runoff; 3) increased sediment deposition from wetland plants and freshwater and estuarine
bivalves; 4) terrestrial weeds increasing nutrient loading by increasing soil nitrogen; and 5)
sudden release of nutrients with the senescence of aquatic weeds. The impacts on water quality
can be substantial. A modeling simulation of SaginawBay (Endicott et al., 1998) predicted that
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zebra mussels increase the flux of particles and particle-associated contaminants from the water
column to the sediment by seven-fold.
Aquatic invasive species can also affect the potential for biomagnification and the transfer of
pollutants to wildlife by altering food webs. The potential for biomagnification of PCBs
increases with invasions of zebra mussels (Bruner, et al. 1994). Changes in the food web
following the invasion of the Asian clam (Potamocorbula amurensis) into San Francisco Bay has
resulted in higher selenium concentrations in diving ducks (Thompson and Luoma, 1999) and
perhaps sturgeon (http://iep.water.ca.gov/eet/min9706.html).
Invasions of exotic pests also indirectly degrade water quality by resulting in increased
pesticide usage. As discussed below ("V-16. Pesticide Use and Pollution Prevention"), a
substantial portion of all pesticides are targeted for exotic pests; presumably these same pesticides
are also responsible for a corresponding proportion of pesticide-related water quality problems.
In some cases, nonindigenous species improve water quality. As mentioned, Hydrilla may
reduce algal blooms by binding the nutrients during the active growing season (see "10-D.
Nutrient Fluxes"). Hydrilla and water hyacinth have also been used to remove soluble pollutants
from contaminated ponds. Perhaps the largest scale improvement in water quality is due to the
zebra mussel. Filtration of water-column parti culates by zebra mussels has been sufficient in parts
of the Great Lakes to result in the clearest water in decades. While decreasing turbidity reduces the
most visible manifestation of eutrophication, increased water clarity without a concurrent decrease
in nutrient concentrations can result in unanticipated effects including increases in harmful blue-
green algae or nuisance macrophytes (see "V-9. Drinking Water Quality").
V-9. Drinking Water Quality:
Blooms of the blue-green algae Microcystis and benthic macroalgae have recently resulted in
taste and odor problems in portions of the Great Lakes. One explanation is that by increasing
water clarity and reducing the natural phytoplankton populations, filtration by zebra mussels has
created conditions promoting these nuisance algae (Vanderploeg and Nalepa, 1995 in Glassner-
Shwayder, 2000; http ://www. sgnis. org/publicat/96vander. htm). Taste and odor problems can
also result from decaying mats of the exotic Eurasian watermilfoil and other aquatic weeds.
Water-borne pathogens from ballast water discharges are another potential threat, though we are
not aware of any cases of disease resulting from ballast water discharges into drinking water
supplies (versus ingestion of contaminated shellfish).
V-10. Open Ocean Disposal of Dredge Material:
Under the Marine Protection, Research, and Sanctuaries Act (MPRSA), the ocean disposal of
materials that would "adversely affect human health, welfare, or amenities, or the marine
environment, ecological systems, or economic potentialities" is prohibited or severely limited.
Environmental concerns to date have focused on the toxicity and bioaccumulation potential of
dredge materials, though there is a growing recognition that dredge material is also a potential
transport vector for nonindigenous species.
Ocean disposal of dredge material inoculates offshore ecosystems with literally millions of
nonindigenous individuals, though it is not clear how well these species survive in an oceanic
environment. Even if the nonindigenous species do not become established offshore, ocean
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disposal may facilitate their transport along the coastline to other near-coastal habitats. Another
risk is the direct transport of nonindigenous species on the dredger, though this can be minimized
by careful cleaning between operations. These various risks should be evaluated both in locating
dredge disposal sites and in assessing any particular disposal operation. If the risks are too great,
other disposal options might be required.
V-ll. Inland Disposal of Dredge Material:
Section 404 of the Clean Water Act regulates the discharge of dredged or fill material into all
fresh, estuarine, and marine waters landward of the territorial sea. Discharge is prohibited if the
material "will have an unacceptable adverse effect on municipal water supplies, shellfish beds
and fishery areas (including spawning and breeding areas), wildlife, or recreational areas."
Sediment toxicity, bioaccumulation potential, and wetland loss have been the primary
environmental concerns to date; as with open ocean disposal, there is a growing recognition for
the potential transport of invasive species. However, with inland disposal there is a greater risk
of the transported organisms becoming established since inland dredge and disposal habitats are
more likely to be similar than are near-shore and oceanic habitats. An additional risk with inland
disposal is the transport of exotic plants or their seeds. As with ocean disposal, the potential for
transporting nonindigenous species needs to be considered both in locating disposal sites and in
evaluating the environmental risks from any particular disposal operation.
V-12. Endangered Species Act:
The Endangered Species Act (ESA) is administered by the U.S. Fish and Wildlife Service and
the National Marine Fisheries Service. EPA's role is to coordinate the Clean Water Act with
those two agencies so as not to jeopardize endangered species. As discussed above ("IV-1.
Biodiversity"), invasive species are second only to habitat degradation as a stressor on threatened
and endangered species. Because the stress imposed by invasive species reduces the
"assimilative capacity" of these restricted populations to cope with other insults, more stringent
point and nonpoint controls may be required to maintain viable populations. As impacts from
invasive species increase, pollutant control measures that have been sufficient historically may
no longer prove protective, and stricter pollution controls may be required in the future just to
maintain the status quo.
V-13. Biocriteria:
Biological criteria are "numeric values or narrative expressions that describe the reference
biological condition of aquatic communities inhabiting waters of a given designated aquatic life
use" (http ://www. epa. gov/owow/monitoring/tech/chapO 1.html). Invasions of nonindigenous
species confound the interpretation of many of the approaches to establishing biological criteria.
Historical reference conditions are frequently used as a standard for defining ecological
condition or as a calibration for ecological metrics. However, in a highly invaded community it
is difficult to ascertain whether differences between historical and present conditions are due to
exotic species, other anthropogenic stressors, or some interaction between the two. For example,
is the change in trophic structure in San Francisco Bay solely a consequence of the invasion of
the Asian clam (Potamocorbula amurensis) or does sediment contamination contribute directly
or indirectly to the changes (see Lee et al, 1999; U.S. EPA, 2001)?
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Even if an historical approach is not used, the presence of nonindigenous species confounds
the interpretation of commonly used indices of community structure (e.g., diversity, proportion
of pollutant-tolerant groups) and function (e.g., proportion of different feeding groups). For
example, amphipods are frequently used as a "pollution-sensitive" taxon, yet the total density of
amphipods increased along a DDT gradient because of the high density of a pollutant-tolerant
nonindigenous amphipod (Lee et al., 1994). As discussed above ("IV-1. Biodiversity"),
introductions of nonindigenous species can increase species richness. A possible scenario is that
a disturbed site could have a higher species richness than a reference site because of a high
invasion rate. Under this scenario it is not clear how to interpret species richness as a measure of
ecological condition.
There is a need to develop ecological indicators that capture the impacts of nonindigenous
species on ecosystem structure and function. A few structural indices have been proposed based
on the percentage of native versus nonindigenous species (e.g., "native species indicator" of the
NRC, 2000a; (http ://www. nap, edu/books/03 09068452/html). One limitation of the existing
indicators is that they do not account for future impacts of nonindigenous species that are
presently at low numbers but that have the potential to "explode" to invasive densities. A lake
recently invaded by zebra mussels would not have been measurably altered by this invasive
species, yet any biocriterion failing to recognize the lake's low ecological sustainability would
give a misleading picture of its "ecosystem integrity". Another policy/science issue is how to
incorporate "desirable" non-native species into biological criteria. One example is the stocking
of exotic trout versus their impacts on native fish assemblages. A biocriterion based on
recreational fishing would rank a stocked stream in good condition while a biocriterion based on
a comparison to a natural reference would indicate the ecosystem is impaired.
V-14. Monitoring/Research Programs and Taxonomic QA/QC:
Tens, if not hundreds, of millions of dollars are spent each year for compliance monitoring of
aquatic communities throughout the country (e.g., 305b, 301h, NPDES, etc.). These regulatory
programs could substantially contribute to the detection of range expansions of existing invasive
species and act as early warning systems for newly introduced nonindigenous species.
Developing such systems requires taxonomy of high quality (e.g., not mislabeling a new
exotic as a local species). Achieving this level of taxonomic accuracy will require EPA to
institute taxonomic QA/QC requirements equivalent to those used for chemical analysis. With its
experience with analytical QA/QC, the EPA has the infrastructure to institute these requirements,
though it would be necessary to partner with other entities (e.g., Smithsonian Institution) with
more taxonomic expertise to establish the standards. Requiring high quality taxonomy will
require additional resources, but these costs could be justified by the need to separate the effects
of invasive species versus pollutant effects. One limitation is the lack of regional lists of
nonindigenous species for many areas, as was developed for San Francisco Bay (Cohen and
Carlton, 1995), though these could be developed at a relatively modest cost. Another limitation is
the general lack of trained taxonomists for many taxa.
ORD research programs can also contribute to the detection of nonindigenous species. In
particular, EMAP, which uses a probabilistic sampling approach to estimate the ecological
condition of the Nation's waters (http: //www. epa. gov/emapX could serve this purpose.
Probability-based sampling provides an unbiased estimate of the extent of the targeted stressors,
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and this sampling approach determined that introduced fish were one of the most regionally
extensive stressors in the Mid-Atlantic Highlands area (see "II-5. Recreation - Fishing" and
http://www.epa.gov/emap/maia/html/rabrief/slide 14.html). More recently, results from the
EMAP Western Pilot were analyzed to evaluate differences in the extent of invasion among
Oregon, Washington, and California small estuaries and whether the extent of invasion was
related to estuary size (Lee et al, 2001).
V-15. Ecological Risk Assessment:
Ecological risk assessments are a promising approach to addressing some of the complex
problems associated with invasive species. For example, they could be used to: 1) evaluate
proposed intentional introductions; 2) compare the relative environmental impacts of control
scenarios for unintentional introductions (e.g., no treatment vs. aggressive use of herbicides); 3)
evaluate the risks from ballast water discharges from different parts of the world; or 4) evaluate
the impacts of invasive species in comparison to other anthropogenic stressors. One of advantage
of a risk assessment approach is the formalization of the problem and of the approach to
assessing the risks.
There are, however, a number of complexities inherent in assessments with invasive species.
To an even greater extent than with pollutants, it is critical to define measurable assessment
endpoints of value to the public. While nearly everyone agrees that pollutants are undesirable, there
is much less agreement about what constitutes a "good" versus "bad" species or ecosystem. This
lack of agreement renders the use of broad endpoints such as "ecosystem integrity" of limited use
for invasive species. For example, would ecosystem integrity be considered impaired if the species
composition had been substantially altered but the ecosystem still provided ecological functions
similar to native habitats? Other complexities include how to incorporate the beneficial aspects of
nonindigenous species in the assessment and to what extent the "precautionary principle" should
be applied to account for potential future impacts. Even a simple attempt at comparing the relative
impacts of nonindigenous species versus those from sediment contamination in San Francisco Bay
revealed the difficulty in defining the "problem" and how to compare impacts from fundamentally
different types of stressors (U.S. EPA, 2001; Lee et al., 1999).
Even when assessment endpoints have been identified, predicting the ecological risks
associated with invasive species is more difficult than with pollutants. Many of these
complexities arise from the difficulties in predicting population dynamics of any species, much
less the species-to-species interactions inherent in invasions (e.g., invasional meltdown).
Additionally, there is the highly stochastic nature of invasions and predicting the effects of
natural and anthropogenic disturbances on invasions. While these problems are difficult, they can
be approached over time in incremental steps with a sufficient research effort. An alternative is
to utilize large safety factors to account for the various uncertainties, but this may prove
politically unacceptable in many cases.
Although these complexities have not yet been rigorously incorporated into risk assessment
procedures, several general guidelines for invasive species are available. The Aquatic Nuisance
Species Task Force developed guidelines for aquatic species (ANSTF, 1996;
(http://ANSTaskForce. gov/gennasrev.htm), which were applied to an assessment of the risks of
viruses spreading from foreign shrimp aquaculture to U.S. aquaculture and wild shrimp
populations (http://www.epa.gov/nceawwwl/svra.htm). USDA's APHIS has "guidelines for
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conducting pest-initiated, qualitative pest risk assessments specifically for determining whether
or not a weed species should be listed in the FNWA [Federal Noxious Weed Act] regulations."
(http://www.aphis.usda.gov/ppq/weeds/weedsrisk99.html). The USGS, National Park Service,
and University of Minnesota created decision support software to rank the relative risk from
existing exotic weeds (http://www.npwrc. usgs. gov/resource/2000/aprs/aprs.htm). While these
guidelines are important first steps, both the risk assessment process and the underlying science
needs to be further developed before accurate quantitative estimates of risk are possible.
V-16. Pesticide Use and Pollution Prevention
A substantial proportion of all pesticides are targeted for use on exotic species. One hundred
twenty-three of the 140 plants on California's Noxious Weed List are nonindigenous. Assuming
that herbicide usage is proportional to the number of weed species, almost 90 percent of the
herbicides used in California are targeted for exotic weeds. Nationally, about 65 percent of all
weeds are exotic, which should generally reflect herbicide usage. A similar pattern is seen with
insects, where approximately 40 percent of insect and mite pests in agricultural systems are
exotic (Pimentel, 1993). These usage patterns suggest that a major portion of all the ecological
and human health impacts resulting from pesticides is a consequence of attempting to control
invasive species.
The relative proportion of pesticides targeted for exotic pests is likely to increase. Only about
a third of the 6741 plant species considered weeds somewhere in the world are presently found in
the contiguous United States (Holm et al., 1979 in Westbrooks, 1998), a staggering pool of
potential exotic weeds. As pointed out in the recent "The Future Role of Pesticides in U.S.
Agriculture" (NRC, 2000b;
(http://www4.nationalacademies.org/news.nsf/isbn/03090652677OpenDocument), "recent
reductions in trade barriers increase the chances that nonnative pests will find their way onto
American soil. New, environmentally compatible chemical pesticides will be needed to
complement a variety of prevention strategies to combat such pests." This continual development
of new pesticides increases the probability of unanticipated ecological and human health
impacts.
Applying the same logic to invasives species as is applied to toxic pollutants, the most cost-
effective and environmentally-friendly approach to mitigating these impacts is pollution
prevention - either preventing the introduction of new exotic pests or, if that fails, a rapid
response to control new introductions while they are still localized. The EPA has a relatively
minor role in the prevention of new terrestrial pests, which largely falls under the jurisdiction of
the USDA. EPA's role in the prevention of new exotics into aquatic ecosystems could be
substantial if the Agency regulates ballast water discharges under NPDES (see "V-5. Ballast
Water and NPDES Permits"). One key role for the EPA in rapid response is the emergency
registration of pesticides (see "V-17. Pesticide Registration").
V-17. Pesticide Registration:
Under Section 18 of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), the EPA
can authorize emergency exemptions to a pesticide's registration, such as for 1) use on crops not
listed in the registration, 2) at higher concentrations, or 3) for the use of a new pesticide before
the registration process is completed. Dr. Robert Eplee (U.S. EPA, 2001) emphasized the
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importance of being able to control invasive weeds by using herbicides outside of their existing
registration. He presented the example of witchweed, which devastates corn crops. The most
effective herbicides for this weed appear to be paraquat (expanded use), oxyfluorfen (new
pesticide), or ethylene (expanded use).
Another of Dr. Eplee's points was that "weeds won't wait". Because of the urgency to
control newly introduced exotic pests while their populations are still localized, Section 18 could
become an important mechanism in approving the use of effective pesticides in a timely fashion.
Recognizing the importance of pesticides in controlling exotic pests, one of the actions specified
for the EPA in the National Invasive Species Management Plan (see "V-l. Executive Order on
Invasive Species") is to develop a proposal to "utilize current programs to facilitate development,
testing, and training of personnel concerning proper use of environmentally sound pesticides in
controlling invasive species populations ..." by January 2002 (see Appendix 1).
There is little economic incentive for pesticide manufacturers to register low-use pesticides
for newly introduced exotics, especially if they are not likely to become agricultural pests. In
these cases, a federal agency (other than EPA) or state agency could act as the registrant. A
precedent is the lampricide used in the Great Lakes where the U.S. Geological Survey-Biological
Resources Division (USGS-BRD) is the registrant under a memo of understanding with the
Great Lakes Fishery Commission (GLFC). It is not clear how, or if, having a federal or state
agency as the registrant would change the registration procedure.
V-18. Superfund and Phytoremediation
As Superfund moves from the problem identification/litigation phase into remediation and
maintenance, the ecological and political ramifications of invasive species become more
important. The primary issues relating to Superfund are similar to those with wetland
remediation (see "V-7. Wetlands Restoration") - use of native species in remediation, whether
remediated sites are prone to invasion, and whether remediated sites serve as centers for the
invasion of surrounding habitats.
Historically, Superfund has approached remediation primarily from an engineering
perspective of stabilizing or cleaning up soils rather than restoring native habitats. Accordingly,
Superfund has often relied on non-native grass species for erosion control and non-native plants
for phytoremediation. For example, the Phytoremediation Bibliography, (http://www.clu-
in.org/products/phytobib/bibm-p.html#OX indicates that the invasive water hyacinth has been
used in clean-ups. It is our impression that Superfund has become more aware of the risks of
using invasive species. In any case, use of invasive species is prohibited under the Executive
Order (see "V-l. Executive Order on Invasive Species") unless "the agency has determined and
made public its determination that the benefits of such actions clearly outweigh the potential
harm caused by invasive species; and that all feasible and prudent measures to minimize risk of
harm will be taken in conjunction with the actions."
The Executive Order has raised a number of policy/legal questions regarding the Superfund
process, including: 1) can the Executive Order be used as a requirement to restore Superfund
sites to native habitats; 2) should Superfund project managers include control of invasives in the
records of decision; 3) can EPA require responsible parties to assume the financial and technical
burden of administrating invasive species control during remediation, monitoring, and
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maintenance; and 4) is it possible to generally include non-native species in decisions or do the
non-native species need to be identified in the decision? These questions are beyond the scope of
this document, but are indicative of the types of issues that invasive species are raising in several
regulatory programs.
V-19. Air Quality:
As discussed above ("11-12. Fires"), invasions of exotic weeds can substantially increase the
frequency and intensity of wild fires. In addition, controlled burns are used to manage certain
exotic weeds. Presumably, these fires could increase particulate concentrations, at least locally.
However, we are unaware of any cases linking fires associated with invasive species to air
quality violations. Air quality may also affect invasive species. In particular, atmospheric
deposition of nitrogen may promote invasive weeds in certain ecosystems.
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VI. RESEARCH NEEDS
No ORD report would be complete without a list of research needs — ours is given in Appendix
3. The research topics in Appendix 3 all potentially relate to EPA's overall mission. Additional
discussion of research topics can be found in the summaries of the National and Regional
Nonindigenous Species Workshops (U.S. EPA, 2001, Lee et al., 1999, and Glassner-Shwayder,
2000). The primary purpose of listing these research topics is as a catalyst for discussions with
the Program Offices and Regions in identifying the highest priority needs. We need to emphasize
that we do not propose that EPA should, much less has the resources, to address all these
research areas. Additionally, as extensive as the list is, it is possible that some high priority
topics may have been omitted.
Several of these research needs, especially those related to assessing ecological condition,
can be integrated into ongoing projects with little change in their goals or methods and with
minimal additional resources. Other projects would require a focused effort, such as an
assessment of ballast water treatment alternatives. Because of the scope of the invasive species
issue, the best strategy is a combination of in-house research, extramural research, and partnering
with the Program Offices, Regions, and other federal and state agencies. While such integration
is an often-stated goal, one of the functions of the Invasive Species Council is to help coordinate
among various agencies. Additionally, the Invasive Species Council will submit a crosscutting
budget proposal for FY03 to "adequately fund Federal invasive species research programs."
which could supplement any Agency in-house or extramural resources.
While a number of other agencies are involved in invasive species research, EPA brings a
unique mix of talents and skills to the problem. More than most other agencies, EPA has a history
of at least attempting to approach environmental problems with an ecosystem approach versus a
single species approach. This more "holistic" view will be critical for addressing some of the key
questions. Additionally, with its broad environmental mandate EPA has experience with terrestrial,
wetland, and aquatic ecosystems. EPA's experience with risk assessment will also be key in
addressing various questions. Finally, though frustrating at times, the interaction between ORD and
the regulatory programs should help keep the research from becoming "too academic".
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VII. CONCLUSIONS
Invasive species are literally changing the American landscape, and the examples provided in this document
only touch on the range of ecological impacts. Every major terrestrial, wetland, and aquatic ecosystem has been
invaded and nearly every ecosystem service has been degraded to some degree. Invasive species are responsible for
more ecological havoc than all pollutants combined, second only to habitat loss. Ecological conditions will continue
to degrade unless the existing invasive species are actively managed and the influx of new exotics is drastically
reduced.
It is becoming increasingly recognized that invasive species also represent a human health threat. It is not beyond
the realm of possibility that one of the increasingly common exotic diseases could result in a regional or national
outbreak. One vector of particular importance to the EPA is the transmission of water-borne diseases, in particular
cholera, through ballast water discharges. Because of their prevalence as agricultural and household pests, invasive
species are indirectly responsible for a substantial proportion, if not majority, of all human pesticide exposures.
Compared to other federal agencies EPA has not been active in addressing invasive species. Nonetheless,
the invasive species issue is not going away. At a minimum, the EPA will have to address how invasive species
impact the implementation of existing regulations. TMDLs and Superfund site remediation are just two
examples of Agency responsibilities modified by invasive species. EPA will also have to decide what role it
will take in managing invasive species. We expect that public and political pressure on the EPA to address
invasive species will increase. The petition to regulate ballast water, the exotic species TMDL in San Francisco
Bay, and the Invasive Species Executive Order are all harbingers of the future political landscape.
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APPENDICES
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APPENDIX 1: ACTIONS IN THE INVASIVE SPECIES MANAGEMENT
PLAN RELATED TO THE EPA
PROPOSED ACTION FROM MANAGEMENT PLAN
(OCTOBER 2, 2000)3
A. LEADERSHIP
RELATIONSHIP TO EPA
3. By January 2002, the Council will conduct an evaluation of current legal
authorities relevant to invasive species. The evaluation will include an
analysis of whether and how existing authorities may be better utilized.
4. Starting in October 2001, each member Department of the Council shall
submit an annual written report summarizing their invasive species activities,
including a description of their actions to comply with the Order, budget
estimates, and steps in implementing the Plan.
7. Beginning with Fiscal Year (FY) 2003, and each year thereafter, the
Council will coordinate and provide to the Office of Management and
Budget (OMB) a proposed cross-cut budget for Federal agency expenditures
concerning invasive species.
Relates to EPA's legal reviews of
using NPDES for ballast water and
whether invasives are "pollutants".
OGC.
Agency's response will be open for
review by politicians and public.
Response will require coordination
across Agency.
Opportunity to increase research
efforts in ORD and implementation
by Offices and Regions.
earch
lentation
10. By February 2001, the Council will convene a working group of agency
leads on international agreements relevant to invasive species in order to
facilitate communication and the development of U.S. positions that have
adequate stakeholder input and are mutually supportive.
Relates to border treaties; OIA, Great
Lakes Program, border Regions.
Other international agreements?
12. By August 2001, the Council in cooperation with the President's Council
on Environmental Quality (CEQ), will prepare and issue guidance to Federal
agencies based on the National Environmental Policy Act (NEPA) for
prevention and control of invasive species.
EPA reviews of environmental
assessments (EAs) and environmental
impacts statements (EISs) under
NEPA - Regions and Office of
Federal Activities.
B. PREVENTION
INTENTIONAL INTRODUCTIONS
14. By December 2003, the Council will develop a fair, feasible, and risk-
based comprehensive screening system for evaluating first-time intentionally
introduced non-native species (see items a-e below).
Definition of impairment and
implementation of TMDLs under
305(b) and 303(d) for stocked fish.
Development of risk-based approach.
3 The left-hand column are the action items in the final version (January 18, 2001) of the Invasive Species Plan
("Meeting the Invasive Species Challenge") that most directly relate to EPA. The numbers for the action items
are those used in the Plan. In some cases the action items are abbreviated. Specific mention of the EPA or EPA
regulations are bolded. The right-hand column is our interpretation of some of the ways the action item could
impact the EPA and/or the EPA organization potentially affected by the action item.
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PROPOSED ACTION FROM MANAGEMENT PLAN
(OCTOBER 2, 2000)
15. By 2006, the same Federal agencies (as designated under a-e below) will
develop modifications to the screening system or other comparable
management measures (i.e., codes of conduct, pre-clearance or compliance
agreements) to formulate a realistic and fair phase-in evaluation of those
intentional introductions.
15a. Introduction of non-native biological control organisms for animal pest
control within the continental U.S. to complement measures already in place
for screening of plant biological control organisms. Lead Departments:
USDA, Interior, and Environmental Protection Agency (EPA).
15b. Introduction of all non-native freshwater or terrestrial organisms for any
purpose into Hawaii, Puerto Rico, the U.S. Virgin Islands, or U.S. territories
or possessions in the Pacific and the Caribbean (because of the vulnerability
of insular areas, a separate screening process for those areas is needed). Lead
Departments: USDA, Interior and EPA, the State of Hawaii, and the
Governments of Puerto Rico and the Virgin Islands.
RELATIONSHIP TO EPA
15e. Introduction of non-native aquatic organisms for any purpose (e.g., fish
or shellfish stocking, aquarium organisms, aquaculture stock, aquatic plants
and biological control agents) within the continental United States. Lead
Departments: USDA, Interior, and Commerce, EPA, and the Army Corps of
Engineers.
OPPTS responsible for microbial
pesticides under FIFRA. Regions
review under NEPA?
obial
gions
OW and Regions 2 and 9; ORD
develop a screening process.
Discharges from aquaculture under
NPDES. Use of non-native species in
water-column or sediment bioassays.
Biocontrols under NEPA.
UNINTENTIONAL INTRODUCTIONS
16. Federal agencies will take the following steps to interdict pathways that
are recognized as significant sources for the unintentional introduction of
invasive species:
16a. By July 2001, NOAA, the Coast Guard, Interior, and EPA will sponsor
research to develop new technologies for ballast water management, because
the current method of ballast water management—ballast water exchange—is
recognized as only an interim measure to address non-native species
introductions.
20. By January 2003, the Council will implement a system for evaluating
invasive species pathways and will issue a report identifying, describing in
reasonable detail, and ranking those pathways that it believes are the most
significant. The report will discuss the most useful tools, methods, and
monitoring systems for identifying pathways, including emerging or changing
pathways, and for intervening and stopping introductions most efficiently.
_
Ballast water research/validation by
ORD, OW, Great Lakes Program, or
Regions. Risk assessment approach
to ballast water management?
OW in relation to ballast water,
aquaculture discharges, and dredging.
ORD conduct risk assessments on
pathways.
C. EARLY DETECTION AND RAPID RESPONSE
EARLY DETECTION
21. The Council will improve detection and identification of introduced
invasive species, recognizing the need for jurisdictional coordination, by
taking the following steps:
21c. By January 2003,USDA, Interior, Commerce, and EPA will institute
systematic monitoring surveys of locations where introductions of invasive
species are most likely to occur (e.g., ports, airports, railroads, highway
rights-of-way, trails, utility rights-of-way, logging and construction sites). In
Monitoring of ports could incorporate
ongoing compliance monitoring,
and/or be a separate program -
Region or ORD lead? Research on
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PROPOSED ACTION FROM MANAGEMENT PLAN
(OCTOBER 2, 2000)
addition, by January 2002, highly vulnerable sites that may warrant more
intensive and frequent monitoring than other sites will be identified.
RELATIONSHIP TO EPA
monitoring designs for invasive
species (e.g., EMAP approach vs.
qualitative surveys).
RAPID RESPONSE
23c. The Council will review and propose revisions of policies and
procedures (i.e., advance approval for quarantine actions, pesticide
applications, and other specific control techniques, and interagency
agreements that address jurisdictional and budget issues) concerning
compliance with Federal (e.g., Clean Water Act, National Environmental
Policy Act, Endangered Species Act) and non-federal regulations that apply
to invasive species response actions.
Use of Section 18 under FIFRA for
emergency use of pesticides not
covered under the registration. OW in
terms of water quality criteria.
D. CONTROL AND MANAGEMENT
26. By February 2002, the Council will identify and, as appropriate, adopt
sanitation and exclusion methods for preventing spread of invasive species
(e.g., restrictions on use of contaminated soils and fills, cleaning fire-fighting
equipment before deployment to new areas, requiring pest-free forage and
mulch and weed-free sod, washing of construction equipment, and managing
ballast water).
28. By January 2002, the USDA, in consultation with regional, State, tribal,
and local agencies, will develop a proposal for accelerating the development,
testing, assessment, transfer, and post-release monitoring of environmentally
safe biological control agents and submit the proposal to the Council for
review.
Dredge/fill under 404 of CWA &
MPRSA. OW with ballast water
management. Superfund
remediation?
Responsibilities under NEPA and
FIFRA.
29. By January 2002, EPA will develop and provide to the Council a proposal
for cooperation with private industry. The proposal will utilize current
programs to facilitate development, testing, and training of personnel
concerning proper use of environmentally sound pesticides in controlling
invasive species populations, consistent with the 1996 Food Quality
Protection Act (P.L. 140-170) and the Federal Insecticide, Fungicide and
Rodenticide Act (FIFRA).
32. By January 2003, the Council will develop and guidance [sic] for ranking
the priority of invasive species control projects at local, regional, and
ecosystem-based levels.
OPPTS responsibilities under FIFRA
and Food Quality Protection Act.
Development of risk assessment
approaches.
E. RESTORATION
35. By July 2002, the Council will develop and issue recommendations,
guidelines and monitoring procedures for Federal land and water management
agencies to use, where feasible, in restoration activities. Among other things,
these will:
35a. Address restoration programs mandated by law (e.g., natural disasters,
oil and chemical spills, and acid mine drainage).
35b. Identify the appropriate uses of native and desirable non-native species
and encourage management practices that promote regeneration of native
species.
Restoration under Superfund
including phytoremediation. Wetland
restoration under mitigation banking
(Section 404).
Restoration under Superfund
including phytoremediation. Wetland
restoration under mitigation banking
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PROPOSED ACTION FROM MANAGEMENT PLAN
(OCTOBER 2, 2000)
35c. Develop and describe the best available techniques for restoring habitats
such as arid and aquatic environments and highly eroded or disturbed sites,
and identify research needs for technique development.
RELATIONSHIP TO EPA
(Section 404).
Wetland restoration under mitigation
banking (Section 404). Other aquatic
habitats? ORD develop approaches.
F. INTERNATIONAL COOPERATION
38. By December 2001, the Council will outline an approach to a North
American invasive species strategy, to be built upon existing tripartite
agreements and regional organizations, and initiate discussions with Canada
and Mexico for further development and adoption.
Article IV of the Boundary Waters
Treaty with Canada addresses aquatic
invasive species. Additional
obligations under the US-Canada
Great Lakes Water Quality Agreement
(GL WQA)? Other border treaties?
G. RESEARCH
43. By July 2001, the Council, in coordination with FICMNEW, SI, the
ANSTF, and CENR, will prepare a catalog of existing aquatic and terrestrial
control methods — The catalog should include the following:
43a. Validation methods to measure and report removal efficiency, cost-
effectiveness, safety, and practicality under real-world conditions.
43b. Treatments and effectiveness measurement protocols.
45. By July 2002, the Council, SI, and NSF, utilizing input from CENR, will
establish and coordinate a long- and short-term research capacity ranging
from basic to applied research on invasive species. This initiative will build
on existing efforts that reflect a range of perspectives and program
approaches. It will address research, monitoring, information sharing
(including mapping), assessment, control, and restoration. It will identify
personnel and resources needed to sustain fundamental research and tactical
or field-level scientific support which include:
agency core cap,
45b. Enhancement of current competitive grants programs and mechanisms
for cooperative support of research by public and private universities, Federal
and State governments, and the private sector to complement core research
capabilities.
46. As part of the cross-cut budget proposal for FY 2003, the Council will
include an initiative to adequately fund Federal invasive species research
programs. ... The proposal will address research issues such as:
46a. Determine how and to what extent invasive species affect populations of
native species, endangered and threatened species, habitats, animal health,
human health, and native species biodiversity.
Ballast water treatment research,
OPPTS involved with safety of
pesticides.
Involvement of ORD and
Environmental Technology
Verification (ETV) program, in
particular with ballast water
treatment.
ORD can contribute especially in
monitoring design & interpretation,
effects on ecosystem functioning,
development of risk assessment
approaches, and effects on pollutant
fate and effects.
Effects on in-house ORD efforts anc
resource allocations.
ORD STAR program. Program
Office or Regional projects?
Primarily ORD.
Relation to development &
interpretation of biocriteria.
Protection of endangered species.
Incorporation of effects of invasive
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PROPOSED ACTION FROM MANAGEMENT PLAN
(OCTOBER 2, 2000)
46d. Determine how and to what extent invasive species alter ecosystem (e.g.,
water quality, hydrology, nutrient cycling, and disturbance regimes such as
fire cycles), agricultural, economic, and social processes.
46e. Develop and test monitoring and control protocols, methods, tools, and
strategies to support the prevention of introduction and spread, rapid response,
restoration and containment strategies, including the evaluation of impacts
from management activities.
RELATIONSHIP TO EPA
species in risk assessment of other
anthropogenic stressors.
Key to understanding effects of
invasives on non-point runoff and
TMDLs - OW and ORD.
Develop/validate control mechanisms
for ballast water. Ecological and
human health effects of control
measures (e.g., discharge of biocides,
effects of pesticides on non-target
species). Validation conducted under
ETV.
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PROPOSED ACTION FROM MANAGEMENT PLAN (OCTOBER RELATIONSHIP TO EPA
2, 2000)
H. INFORMATION MANAGEMENT
50. By November 2001, the Council will develop and secure implementation of a
memorandum of understanding among appropriate Federal Departments to
establish an invasive species assessment and monitoring network comprised of
on-the-ground managers of Federal invasive species programs and appropriate
51. By January 2002, Interior, USD A, Commerce, EPA and U.S. Army Corps of
Engineers will develop guidance for managing information concerning invasive
species in aquatic and terrestrial environments.
5 la. Current and emerging technologies for information collection (e.g., GIS and
remote sensing) and data analysis and dissemination, including lower-cost
information tools for wide distribution.
51b. Standard protocols for information collection and sharing, including
taxonomy, identification, inventory and mapping, monitoring, and assessments of
invasive species populations.
51c. Most effective means and appropriate contacts - including those of the
Council - for sharing information with local, State, tribal, Federal, and
international agencies, non- governmental organizations, private citizens, and
other stakeholders, that link to systems currently underway.
I. EDUCATION AND PUBLIC AWARENESS
56. By July 2001, the Council will coordinate development and implementation
of a national public awareness campaign, emphasizing public and private
partnerships.
Incorporation of compliance
monitoring and research monitoring
into the monitoring network. OW,
Regions, and ORD.
Office of Environmental Information
(OEI); interface with STORE! and
other EPA databases.
Research on remote sensing. OEI?
ORD and OW input into protocols
Use of outreach networks developed
by Regions and Program Offices,
especially to States and the regulated
stakeholders.
Use of outreach networks developed
by Regions and Program Offices with
the public. OEI.
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APPENDIX 2: EFFECTS OF INVASIVE SPECIES ON ACHIEVING GPRA
GOALS AND OBJECTIVES
GOAL AND OBJECTIVE
GOAL 1 - CLEAN Am
POTENTIAL EFFECTS OF INVASIVE SPECIES 4
rObjective 1 - NAAQS for ozone and
PM.
Goal 2 - Clean and Safe Waters
Objective 1, Subobjective 1.1 - 95
percent of drinking water systems will
meet 1994 health-based standards.
Objective 1, Subobjective 1.5 -
Increase in waters attaining the
designated uses protecting the
consumption of fish and shellfish.
Objective 1, Subobjective 1.6 -
Exposure to microbial and other
forms of contamination in waters
used for recreation will be reduced.
Objective 2, Subobjective 2.1 -
Restore and protect watersheds so
that 75 percent of waters support
healthy watersheds.
Objective 2, Subobjective 2.2 - Net
increase of 100,000 acres of
wetlands.
Objective 2, Subobjective 2.3 -
Provide means to identify, assess, and
manage aquatic stressors (ORD has
lead).
Objective 2, Subobjective 2.4 -
Restore and maintain integrity of
Chesapeake Bay, Gulf of Mexico and
National Estuary Program
ecosystems.
GOAL AND OBJECTIVE
Regional and local effects on PM levels resulting from increased fire frequency due to
flammable exotic weeds.
Harmful algal blooms (HABs) and macrophytes resulting in taste & odor problems.
Shellfish contamination and closures resulting from harmful algal blooms (HABs) seeded
by ballast water discharges. Changes in food web structure increasing trophic transport of
contaminants to fish and shellfish.
Introduction of cholera and other water-borne pathogens through ballast water discharges.
Terrestrial and wetland invaders degrading watershed functions, including pollutant
loadings into surface and estuarine waters. Water quality standards and designated uses
impaired directly by wetland or aquatic invaders.
Invasive wetland plants reducing existing native wetlands. Effects of invasions on the
success of wetland restoration and implications on wetland banking.
he
Requirements for more stringent controls on other stressors because of reductions in the
"assimilative capacity" of native species. Invasive effects on critical habitat types and
functions. Effects of invasives on fate and effects of pollutants.
Effects on species composition, productivity, trophic composition, and
sustainability of the ecological resources of Chesapeake Bay, Gulf of Mexico, and
NEP estuaries.
POTENTIAL EFFECTS OF INVASIVE SPECIES
4 This table presents our assessment of the GPRA Goals and Objectives impacted by invasive species. The
potential effects on the GPRA Goals and Objectives are presented as examples; there may be additional effects.
The exact nature and extent of the impact of invasive species on the performance measures for an Objective will
vary depending upon a suite of factors, such as the specific invasive species, ecosystem type, and regional
characteristics (e.g., effects of increased fire on air quality more important in arid West than on East coast).
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Objective 3, Subobjective 3.2 -
Nonpoint source loadings (especially
sediment and nutrient loads) will be
reduced.
By altering erosion, deposition, and nutrient dynamics, invasive terrestrial and wetland
plants can alter loadings into surface and estuarine waters.
Goal 3 - Safe Food
Objective 1 -Reduce agricultural
pesticide risk.
Goal 4 - Pollution Prevention and
Reducing Risk
Objective 1 - Reduce public and
ecosystem exposure to pesticides.
Objective 5 - Improve pollution
prevention strategies, tools,
approaches.
Goal 5 - Better Waste
Management, Restoration of
Contaminated Sites, and
Emergency Response
Objective 1 - Reduce or control risks
to human health.
Goal 6 - Reduction of Global and
Cross-Border Environmental Risks
Objective 1 - Reduce transboundary
threats: North American ecosystems.
Continued introduction of new exotic pests requires increased use of existing pesticides
and/or development of new pesticides. Registration of biopesticides as biocontrols for
exotic pests.
Increased use of existing and new pesticides to control exotics in urban settings and homes
increases public's exposure. Use of these pesticides increases ecosystem exposures via
runoff and drift. Exposure from pesticides used to manage invasives in public lands.
A key method of reducing pesticide exposure is to prevent the introduction of new exotic
pests, many of which require higher concentrations of existing pesticides or new pesticides.
Rapid response to new introductions.
Objective 2 - Climate change.
Objective 4 - Protect public health
and ecosystems from persistent
toxics.
Goal 7 - Expansio
Right to Know
Objective 1 - Increase
quantity/quality of education,
outreach, data availability.
Limitations on using exotic species in phytoremediation and other restoration activities.
Potential for remedial actions to promote spread of invasive species through the creation of
disturbed habitat susceptible to invasion. Question whether sites need to be restored to
"native" conditions.
Transport of invasive species is covered under Boundary Water Treaty with Canada, which
impacts North Dakota water diversion projects. Effects on other boundary agreements (e.g.,
Great Lakes and Puget Sound).
Invasive plants can dramatically alter patterns and rates of carbon sequestration while
increased fire frequency increases CO2 inputs. Climate change is likely to increase invasion
rate and spread of exotic species, including pathogens and their vectors.
Effects of invasives increasing runoff and hence loadings of pollutants. By altering
structure of aquatic food webs, invasive species can alter the fate of persistent toxics,
potentially increasing concentrations in fish, shellfish, and wildlife. Requirements for more
stringent controls on toxics because of reductions in the "assimilative capacity" of native
species.
In coordination with the Invasive Species Council, the EPA could use its existing
infrastructure to educate state agencies, tribes, the public, and the regulated community in
the areas related to the Agency's mission (e.g., dredge disposal, use of exotic species in
bioassays and phytoremediation, NPDES discharges, NEPA).
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GOAL AND OBJECTIVE
Goal 8 - Sound Science
Objective 1 - Ecosystem assessment
and restoration.
anc
Objective 3 - Emerging risks.
Objective 4 - Pollution prevention
and new technology.
Objective 8 - Regional enhancement
of ability to quantify environmental
outcomes.
Goal 9 - Credible Deterrence to
Pollution
POTENTIAL EFFECTS OF INVASIVE SPECIES
EMAP and other programs establish baselines for nonindigenous species as well as relative
impact on aquatic resources. Develop biological indicators incorporating presence and
effects of invasive species. Research on the effects of invasives on the fate of pollutants and
on effects of anthropogenic stressors on promoting invasions.
Extramural research on nonindigenous species through STAR program.
Validate effectiveness of ballast water treatment techniques through inhouse research
and/or extramural programs (e.g., ETV or STAR).
Develop specific regional information to allow Regions to incorporate invasive species
effects when evaluating relative ecological risks and effectiveness of management actions.
Involvement of the Agency in the regulation of invasive species will increase demands on
enforcement and compliance monitoring. In particular, NEPA, NPDES, TMDLs, and
FIFRA have been suggested as regulatory "hooks" to manage invasive species.
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APPENDIX 3: INVASIVE SPECIES RESEARCH NEEDS
The research needs presented here relate to EPA's mission to a greater or lesser extent, research obviously
outside of EPA's mission (e.g., methods to monitor agricultural pests) is not included. Listing of these topics
does not imply that EPA should, or has the resources, to address all these topics. Several of these research topics
could be integrated into existing programs while others would require a targeted research effort.
I. BALLAST WATER AND OTHER AQUATIC VECTORS
A. Ballast Water Exchange and Alternative Treatment Systems
Conduct risk analyses to determine what type (e.g., size, taxonomic class) of organisms need to be
removed from ballast water to protect human health and/or ecological systems.
Determine effectiveness of mid-ocean ballast water exchange in terms of removal of various types of
organisms. Evaluate how effectiveness varies with such factors as duration of the voyage, size of ship,
sediment load in ballast tanks, "no ballast on board" (NBOB) vessels, etc.
Evaluate the effectiveness and practicality of ballast water treatments systems. Potential treatments
include: 1) providing clean ballast water initially (e.g., freshwater); 2) filtration (e.g., centrifugation); 3)
biocides; 4) UV; 5) heat; and 6) shoreside treatment system including discharge into sewage systems.
Evaluation needs to include costs, environmental impacts, and safety.
Develop diagnostic chemical or physical measures to determine whether a ship has exchanged its coastal
ballast water with ocean water.
B. Exposure & Effects of Ballast Water
Evaluate whether ballast water discharges promote harmful algal blooms (HABs) by releasing spores of
toxic dinoflagellates or by other mechanisms.
Evaluate the link between ballast water discharges and outbreaks of cholera and other water-borne
pathogens.
Determine how effective ballast water exchange and/or alternative treatment processes need to be to
adequately protect against the establishment of nonindigenous species (e.g., is 100 percent removal
necessary or is 95 percent sufficiently protective?).
C. Other Aquatic Vectors
Evaluate the role of the fouling organisms on hulls of ships and the aquarium, bait, and live seafood
industries as vectors for introductions.
II. BIOLOGY AND LIFE HISTORIES OF NONINDIGENOUS SPECIES
Conduct life-history and physiological studies on a suite of aquatic and wetland exotic species. Focus on
identifying critical life history stages for control (e.g., sea lamprey), predicting impacts on ecosystem
structure and function, and elucidating common traits of successful invaders.
Evaluate the potential for hybridization between nonindigenous native species. Predict the impacts of
hybridization on the sustainability of the native populations.
III. INVASION THEORY AND ECOSYSTEM VULNERABILITY
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Evaluate the relationship of anthropogenic stressors (e.g., pollutants, sediment runoff, water diversion)
and the susceptibility of aquatic ecosystems to invasions.
Develop the basic biology and the models to predict which nonindigenous species presently at low
densities will become invasive (e.g., changes in life history structure to predict population explosions).
Evaluate the role of increased nitrogen levels on promoting invasive weeds. Determine the role of
atmospheric inputs in the spread of invasive weeds.
Develop the data/models to predict the types of impacts that "keystone" invaders have on the structure
and function of different ecosystem types, such as filter-feeding bivalves on freshwater and estuarine
ecosystems.
Develop methods and the data to predict the likely sources and vectors for invasions into different
ecosystems by biogeographical regions. Include regional studies of shipping patterns to determine the
amount and sources of ballast water into different water bodies.
Evaluate the ecological impacts of nonindigenous species on Hawaii, other island ecosystems, and other
functionally isolated systems.
IV. ECOSYSTEM STATUS AND MONITORING
Using both available data and new field data, quantify the extent and nature of invasions in different
aquatic habitat types by biogeographical regions. Evaluate both at fine and coarse scales (e.g., within
habitat, within region).
Develop monitoring approaches for detecting the early presence of new exotic species, including use of
qualitative surveys, data from compliance monitoring, and observations from stakeholders (e.g., power
plant operators). Develop strategies and networks to integrate these various approaches.
Evaluate use of genetic markers as a rapid detection method for the larval stages of aquatic
nonindigenous species that have not yet established obvious adult populations.
Develop and validate remote sensing technologies to monitor for nonindigenous plants in terrestrial and
wetland ecosystems (e.g., use of hyperspectral analysis).
Address the sufficiency/accuracy of taxonomic identifications in research and compliance monitoring
programs, including QA/QC strategies and requirements.
V. BIOCRITERIA AND CRITICAL HABITATS
Develop biocriteria reflective of the present and potential future ecological impacts of nonindigenous
species. Develop both structural and functional metrics.
Develop biocriteria or other methods to evaluate the total impact of "desirable" nonindigenous species
(e.g., stocked fish)
Develop biocriteria or other methods to evaluate the cumulative impacts from multiple "benign"
nonindigenous species.
Evaluate the impact of nonindigenous species on "critical habitats", such as coral reefs and submerged
aquatic vegetation (SAV). Develop models to predict the future changes in the area and fragmentation of
critical habitats in response to invasions.
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VI. WILDLIFE
Evaluate the direct (predation, competition) and indirect (habitat alteration) effects of nonindigenous
species on wildlife populations. Incorporate habitat-related impacts into spatially-explicit population
models.
Evaluate the role of exotic pathogens on wildlife populations, in particular amphibians and fish
populations. Evaluate intermediate hosts and the vectors transporting these pathogens both within and
among biogeographical regions.
VII. WETLAND, RIPARIAN, AND UPLAND REMEDIATION
Develop methods for the construction and maintenance of wetlands, riparian zones, and upland habitats
that minimize invasions by exotic weeds.
Develop methods and guidance for the control of specific wetland invaders (e.g., Spartina) and upland
invaders. The analysis should include efficacy, cost, and impacts on non-target species.
Evaluate the risk of remediated sites becoming invasion "hot spots" for neighboring habitats.
Evaluate alternatives to exotic species for phytoremediation in aquatic, wetland, and terrestrial habitats.
When no viable alternative exists, develop guidance to minimize the risks of the spread of exotic
species.
VIII. NUTRIENT CYCLES AND NON-POINT RUNOFF
Evaluate the effects of invasive terrestrial plants on the hydrologic cycle and the runoff of clean
sediments, nutrients, and toxic pollutants. Include changes in fire frequency/intensity as one of the
parameters.
Develop models incorporating the effects of exotic weeds on TMDLs for nutrients, pollutants, and clean
sediments. For nutrients, incorporate both changes in runoff and changes in the nutrient cycle (e.g.,
nitrogen fixation).
IX. POLLUTANT DYNAMICS IN AQUATIC SYSTEMS
Evaluate/model how invasive aquatic species alter the flux and fate of pollutants in freshwater and
estuarine ecosystems. The models should include both direct effects, such as filtration of contaminated
particles from the water column, and indirect effects, such as alterations in food webs.
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X. RISK ASSESSMENT METHODOLOGIES
Develop methods to predict the future risks associated with nonindigenous species, including both the
potential expansion of the nonindigenous species populations within a habitat and the spread of the
nonindigenous species to neighboring habitats.
Conduct comparative risk assessments evaluating the relative impact of invasions of nonindigenous
species versus other anthropogenic stressors. One goal would be to rank the relative impacts of stressors
on key assessment endpoints.
Develop methods to compare the ecological and human health risks associated with control measures
(e.g., pesticides, controlled burns) versus the direct impacts of the invasives.
Develop strategies for the incorporation of positive effects of nonindigenous species (e.g., recreation,
soil stabilization) into risk assessments.
XI. HUMAN HEALTH - DIRECT AND INDIRECT
Evaluate the role of ballast water discharges as a dispersal vector for water-borne pathogens such as
cholera.
Evaluate/model the human exposure, and the associated health risks, from pesticides used to control
invasive species in both agricultural and non-agricultural settings. Include analysis of sensitive sub-
groups (e.g., children).
Evaluate the direct and indirect roles of water and sediment quality in the spread of exotic diseases or
their vectors (e.g., loss of frogs allowing increases in mosquitos, which in turn spread West Nile virus)
XII. SOCIOECONOMIC IMPACTS
Estimate the direct and indirect economic costs of nonindigenous species on non-agricultural systems,
especially as they relate to EPA's mission.
Develop innovative methods to educate the public and EPA's stakeholder groups (e.g., dischargers) on
the need for controlling the spread of nonindigenous species.
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