v>EPA
United States
Environmental Protection
Agency
New Indicators of
Coastal Ecosystem
Condition
INTRODUCTION: Coastal ecosystems, from large
estuarine systems to salt marshes, are recognized
for their important ecological function and
societal value. They provide habitat and nursery
grounds for commercially- and recreationally-
important finfish and shellfish. Marshes absorb
energy from storms and protect the land from
hurricanes. These important ecosystems are
threatened by multiple human stressors as well as
natural disturbances. The nation is losing much
of its coastal marsh due to development, land
subsidence, erosion, and sea level rise. In some
areas, invasive species have displaced native
species, threatening commercially important
biological resources by altering habitat and
productivity of the marsh. Reduction of water
clarity, through increases in suspended sediments
and algal blooms, adversely affects the growth of
submerged aquatic vegetation, the nursery grounds
for many fish and shellfish. In order to protect against
continued degradation and loss of coastal ecosystem
services and to plan for their remediation, new
indicators are needed that will predict when and where
ecosystem degradation and wetland losses will occur.
Three ecological indicators of coastal condition are
being investigated by researchers with the Atlantic
Coast Environmental Indicators Consortium (ACE
INC, www. aceinc.org): 1) phytoplankton community
composition; 2) salt marsh elevation and plant health;
and 3) the size distribution of aquatic organisms
(biomass spectra).
1) PHYTOPLANKTON COMMUNITY
COMPOSITION AS AN INDICATOR OF COASTAL
ECOSYSTEM CONDITION
Phytoplankton community composition is a gauge
of ecological condition and change.
Phytoplankton are suspended microscopic
algae. They are the major primary producers in
estuarine ecosystems, have fast growth rates,
and are sensitive to environmental disturbances.
Phytoplankton communities, such as diatoms,
dinoflagellates, chlorophytes, cyanobacteria,
and cryptomonads each have their own unique
diagnostic photopigment signature that can be used
to identify the composition of the phytoplankton
community. (Photopigments, such as chlorophylls
and carotenoids, are molecules that capture and
convert light into chemical energy for powering
photosynthesis).
Watershed/Airshed
Processes
irshed I
" ) Cffecton
Illustration courtesy of Alan Joyner
Figure 1. Roles of diagnostic photopigments as indicators of
ecosystem productivity and plant community composition in
response to physical-chemical stressors in estuarine and coastal
waters.
Ecological Indicator: The structure of phytoplankton communities is a broadly applicable,
integrative indicator of ecological condition of aquatic ecosystems.
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Ecological Effect/Impact: Changes in phytoplankton community composition are important
indicators of estuarine and coastal ecological condition and health because phytoplankton plays a major
role in primary production, eutrophication (including harmful algal blooms), nutrient cycling, water
quality, and food web dynamics.
Environmental Application: Phytoplankton community composition can serve as an early warning
signal of toxic or hypoxia-generating algal blooms. It has proven useful and applicable for evaluating
ecosystem and regional responses to environmental stressors, including increased nutrient loads,
changes in hydrologic characteristics, and climatic disturbances such as hurricanes and droughts.
Together with the North Carolina Department of Environment and Natural Resources, researchers at
the University of North Carolina at Chapel Hill's Institute of Marine Sciences are using diagnostic
pigment (e.g., chlorophyll a) concentration as the criteria for meeting allowable total maximum daily
(nutrient) loads (TMDLs). In addition, diagnostic photopigments are used to determine phytoplankton
community changes in response to hydrological variability, including hurricanes and droughts. Results
from North Carolina's Neuse River Estuary/Pamlico Sound system show that when conditions
"freshen" in response to hurricanes and flooding, fast growing, low salinity-adapted chlorophytes
(green algae) become dominant (Fig. 2). Conversely, when drought conditions prevail, slower-growing
dinoflagellates prevail in wintertime and cyanobacteria (blue-green algae) prevail in summertime (Fig.
2). Cyanobacteria can be especially dominant when a moderate to wet spring is followed by summer
drought conditions. This sequence of events introduces high nutrient loads, followed by a reduction
in flow and flushing, and subsequent retention of the nutrients; an ideal scenario for cyanobacterial
blooms. Aside form impacting water quality, such hydrologic and nutrient-driven changes have
Figure 2. Contribution of some key phytoplankton taxonomic groups (chlorophytes, cyanobacteria and
dinoflagellates) to total chlorophyll a concentrations in the Neuse River Estuary, NC. The dates of landfall of the
seven major hurricanes that have significantly affected flow and nutrient enrichment since mid-1996 are shown.
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significant food web ramifications,
affecting finfish and shellfish productivity
and habitability in estuaries.
Photopigments also provide a key data
source for verification and calibration
of remote-sensing measurements of
phytoplankton production and community
composition for estuarine and coastal
water bodies nationally. The use of remote
sensing allows researchers and managers
to "scale-up" to whole ecosystem
assessments of productivity and ecological
condition. For example, in the Chesapeake
Bay, aircraft-based remote sensing data
are being coupled to diagnostic pigment
analysis to "scale-up" assessments of
nutrient and freshwater discharge controls
on phytoplankton and bloom formation for
the entire estuary at monthly and seasonal
intervals (Figure 3). These indicators
are also now part of unattended water
quality monitoring of estuarine and coastal
sounds. Data from regular ferry crossings
were used as indicators of large-scale
assessment of the impacts of Hurricane
Isabel (Sept. 2003) on North Carolina's
Pamlico Sound (www.ferrymon.org).
03-Apr-2003
39.5
39.0
38.5
37.5
Chi [mg/m3]
77.0 76.5 76.0
25-Jul-2003
Chl [mg/m3]
39.5
38.0
37.0 - —
77.0
76.5
76.0
75.5
Figure 3. Chlorophyll (chl-a, mg m~3) distributions in Chesapeake Bay from aircraft
remote sensing of ocean color using SAS III for spring and summer flights in 2003.
Paerl, H.W., L.M. Valdes, J.L. Pinckney, M.F. Piehler, J. Dyble and PH. Moisander.
2003. Phytoplankton photopigments as Indicators of Estuarine and Coastal
Eutrophication. BioScience 53(10) 953-964.
Paerl, H. W., J. Dyble, J.L. Pinckney, L.M. Valdes, D.F. Millie, PH. Moisander, J.T.
Morris, B. Bendis, B., and M.F. Piehler. 2005. Using microalgal indicators to assess
human and climactically-induced ecological change in estuaries. Pp. 145-174, In
S. Bartone (Ed.) Proceedings of the Estuarine Indicators Workshop. Boca Raton.
Florida: CRC Press, Orlando
2) RELATIVE ELEVATION AND PLANT HEALTH AS INDICATORS OF
COASTAL MARSH STABILITY AND PRODUCTIVITY
The health and productivity of
coastal wetlands are dependent
upon the success of the plant life,
which in turn is dependent upon
the plant's relationship to sediment,
sea level, and the tide. Many coastal marshes depend
on sediments supplied by rivers to counteract the
effects of land subsidence, sea-level rise, and sediment
compaction. In some areas, changes on the land have led
to reduced riverine sediment supply to marshes, leading
to a decrease in height relative to mean sea level. Where
dams or levees have been constructed to prevent flooding,
marshes have been cut off from their source of sediment,
and the net effect is conversion of marsh habitat to open
water.
Vertical elevation is a critical variable that determines
the productivity and stability of salt marshes. The long-
term existence of the salt marsh depends on the success
of the dominant plants, such as Spartina and Jimcus,
and their close relationship to sediment supply, sea level
change, and tidal range.
Researchers at the University of South Carolina,
Columbia, SC and the Marine Biological Laboratory,
Woods Hole, MA have developed two coastal indicators
that can be applied to assess the condition of coastal
marshes. One is vertical elevation relative to mean sea
level (geomorphic) and the other is level of stress of
marsh vegetation (physiologic).
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Geomorphic Indicator: The vertical elevation
relative to mean sea level is an important geomorphic
indicator of marsh productivity and stability and is
determined by using Light Detection and Ranging
(LIDAR) remote sensing. This LIDAR elevation
data is combined with a high resolution Airborne
Data Acquisition and Registration (ADAR) digital
camera image of the marsh landscape to construct
a frequency distribution of marsh landcover with
elevations relative to the elevation of mean sea level.
The frequency distribution is then compared to
optimal distributions across the range of tolerance for
the specific vegetation.
Ecological Effect/Impact: The height of coastal
marshes relative to sea level will move upwards
or downwards toward equilibrium with the sea
depending on factors such as the rate of sea level rise
and amount of sedimentation. When this equilibrium
drops below an optimum level either by a rapidly
changing sea level or changes in the supply of mineral
sediment and organic matter, the salt marsh vitality
will decline. A decline in relative elevation of the
marsh surface below an optimum suggests that coastal
marshes are on a course leading to degradation.
Physiological Indicator: The level of stress
of marsh vegetation is an important indicator
of marsh productivity and stability. Two
complementary measurements, one ground-
based and the other remotely-sensed, are
applied to measure stress. The ground-based
technique is based on the fluorescence emitted
by a leaf as measured by a Pulse Amplitude
Modulated (PAM) fluorescence meter and
gives an estimate of the efficiency of energy
utilization by the leaf. A healthy leaf will have
a higher energy efficiency than a leaf that is
stressed. The remotely-sensed measurements
detect different forms of xanthophyll pigments.
Xanthophyll pigments change form in order to
protect the plant's photosytems so can they be
used as an indicator of stress.
Ecological Effect/Impact: The stress of
marsh vegetation, as measured by the spectral
reflectance of plant pigments, is governed by
nutrient and water availability, phytotoxins,
salinity, and relative sea level. Combining
marsh elevation data with measurements of the
level of stress of vegetation is an integrative
indicator of marsh productivity, health, and
stability.
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100x103 -
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CD
CO
* 60x1 03 -
ED
40x103 -
20x1 O3 -
Spartina alterniflora
CO
0.0
0.2 0.4
Elevation (m)
0.6
0.8
Figure 4. The distribution of Spartina habitat elevations at North
Inlet, SC (Tide Range - 1.39 m). Distribution is a function of the
rates of sea level rise and land subsidence.
Environmental Application: These
indicators offer a cost-effective alternative
for assessing risk for wetland loss, as well as
monitoring the condition of coastal wetlands
and the success of restoration efforts. Resource
managers can use this information, for
example, to apply mitigation techniques for
adjusting sediment supply for wetlands at high
risk of inundation.
Moms, J.T., P.V. Sundareshwar, C.T. Nietch, B. Kjerfve, D.R.
Cahoon. 2002. Responses of coastal wetlands to rising sea
level. Ecology 83:2869-2877.
Morris, J.T., D. Porter, M., Neet, P. A. Noble, L. Schmidt, L. A.
Lapine, and J. Jensen. 2005. Integrating LIDAR, multispectral
imagery and neural network modeling techniques for marsh
classification. Int. J. Remote Sensing. (In press).
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3) BIOMASS SIZE SPECTRA AS AN INDICATOR OF
ECOSYSTEM STATE
Abiomass size spectrum (BSS) depicts the abundance
and distribution of organisms by size classes in an
ecosystem. In aquatic ecosystems, the biomass (i.e.,
aggregate weight) of organisms at each level in the
food chain from microscopic phytoplankton to the
largest vertebrate animals is nearly equal. Because
biomass is near equal, numbers of small organisms
greatly exceed numbers of large organisms. Size-
specific predation (big organisms eat smaller ones) in
aquatic communities maintains the observed biomass
size structure and has led to methods for evaluation of
biomass-size relationships to characterize the structure
and state of ecosystems. To derive BSS, data from
monitoring programs on organism abundances must
be aggregated into size categories. BSS models can
serve as ecological indicators because properties of
BSS respond to natural or human-induced stressors.
ACE INC scientists at the University of Maryland are
evaluating BSS as an indicator of ecosystem state in
Chesapeake Bay.
Biomass Size Spectra as Indicators of Ecosystem Status
Unperturbed ecosystem
theoretical slope =-1.0
system
Log Weight Class
Log Weight Class
Illustration courtesy of William J. Connelly
University of Maryland Center for Environmental Science
Figure 5. Conceptual illustration of a normalized biomass
size spectrum (numbers of organisms plotted against weight
classes) in an unperturbed (left panel) and perturbed (right
panel) ecosystem. In a perturbed ecosystem, abundance
of small, undesirable phytoplankton (A) may increase while
abundance and size of large organisms (fish) may decline (B).
As a result, the slope of the disturbed biomass size spectrum
becomes steeper and other statistical properties (e.g., levels of
abundance) may shift.
Ecological Indicator: Changes in the slope or other statistical properties of the
normalized BSS relative to reference standards or historical benchmarks is an indicator
of changes in the abundance and biomass of the suite of organisms in an aquatic
ecosystem.
Ecological Effect/Impact: Changes in the slope of the normalized BSS can be
indicative of changes in the biological community structure, productivity, food-chain
efficiency, predator-prey relationships, and effects of environmental variability, fishing,
nutrient loading, and habitat change. BSS of stressed ecosystems often have steep
negative slopes. For example, in heavily fished ecosystems larger fish may be reduced
in number and biomass. Or, in highly eutrophic ecosystems with excess nutrient
loading, blooms of microscopic phytoplankton can greatly increase the abundance
and biomass of small organisms, leading to stressful conditions such as hypoxia and
mortality of larger organisms (e.g., crabs, fish).
Environmental Application: BSS can be used by managers to describe long-term
effects of stress or the success of restoration efforts in estuaries impacted by human
activities. BSS can be applied to a broad suite of aquatic biological communities,
not only to selected organisms, and thus can indicate how whole ecosystems are
responding to either deteriorating conditions or remediation efforts in resource
management (e.g., better fisheries management, habitat restoration, improved water
quality). Periodic monitoring of sizes and abundances of organisms is required to
apply BSS as an indicator.
Jung, S. and E.D.Houde. 2005. Fish Biomass Size Spectra in Chesapeake
Bay. Estuaries 28(2): 226-240.
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vvEPA
United States
Environmental Protection
Agency
Office of Research and Development
Washington DC
EPA/600/S-05/004
May 2005
EPA's Science to Achieve Results (STAR)
Estuarine and Great Lakes (EaGLe) Program
GLEI
Great Lakes Environmental Indicators Project
University of
Minnesota-Duluth
f }
PEEIR l^ .;
Pacific Estuarine
Ecosystem Indicator
Research Consortium
University of California-Davis
Consortium for Estuarine
Ecoindicator Research for the Gulf of Mexico
University of Southern Mississippi
w
CEERGOM
ASC
Atlantic Slope Consortium
Pennsylvania State University
EaGLe Program HQ
Washington DC
ACE INC
Atlantic Coast Environmental
Indicators Consortium
University of North Carolina, Chapel Hill
• University of Maryland
• University of South Carolina
• Ecosystems Center, Marine Biological Laboratory
• National Oceanic and Atmospheric Administration (NOAA)-
Beaufort, NC
Direct and indirect effects of
human activities have taken a
toll on the nation's estuaries, yet
few direct linkages have been identified
between human activities on land and
responses in estuarine ecosystems. The
Atlantic Coast Environmental Indicators
Consortium (www.aceinc.org) is one
of five national projects funded by
EPA's EaGLe program. The goal of the
EaGLe program is to develop the next
generation of ecological indicators that
can be used in a comprehensive coastal
monitoring program.
Printed on chlorine free 100% recycled paper with
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U.S. EPA
Office of Research and Development
National Center for Environmental Research
Barbara Levinson
202-343-9720
Levinson.Barbara@epa.gov
http://es.epa.gov/ncer/centers/eagles
Atlantic Coast Environmental
Indicators Consortium
University of North Carolina, Chapel Hill
Hans Paerl
252-726-6841,ext. 133
hpaerl@email.unc.edu
www.aceinc.org
U.S. EPA
Mid-Atlantic Integrated Assessment
Patricia Bradley
410-305-2744
bradley.patricia @ epa.gov
www.epa.gov/maia
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