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Final Report: Health Indicators for Salt Marsh Estuaries of the South Atlantic Bight
EPA Grant Number: R825147Title: Health Indicators for Salt Marsh Estuaries of the South Atlantic Bight
Investigators: Alberts, James J. , Kneib, Ronald T. , Newell, Steven Y. , Pennings, Steven
Institution: University of Georgia
EPA Project Officer: Levinson, Barbara
Project Period: October 1, 1996 through September 30, 1999
Project Amount: $786,349
RFA: Ecological Assessment (1996)
Research Category: Ecological Indicators/Assessment/Restoration
Description:
Objective:The research examines development and testing of simple, inexpensive, and rapid methods for assaying and monitoring the general health of salt marsh ecosystems in the southeastern United States. It is designed to examine a suite of salt marsh indigenous organisms to: (1) evaluate methods that determine critical rates within the macrophyte community, focusing on sublethal impacts; (2) determine the efficacy of using reproductive potential of three species of estuarine crustaceans as another measure of sublethal stress; and (3) evaluate a battery of physiological bioassays using short-lived marine microorganisms as indicators of salt marsh ecosystem condition.
Summary/Accomplishments (Outputs/Outcomes):Microtox Laboratory and Field Studies Subproject (Alberts). The objective of this portion of the study to investigate the impact of salinity and natural organic matter on the toxicity of several pollutants to a marine bacterium. The rationale was that the saltmarsh ecosystems of the southeastern Georgia coast are microbial driven detrital systems; thus, the industry standard Microtox bioassay utilizing the marine bacterium, Vibrio fischeri, should be a good surrogate assay for the natural microbial populations present in the sediments. In this way, the Microtox portion of the study was designed to be a "control" field assay to which to compare results of other assays being investigated in the study.
Laboratory studies using the standard Microtox bioassay protocols indicated that copper and mercury toxicity were significantly decreased by increased salinity and the presence of natural organic matter. The concentrations of copper (Cu+2) and mercury (Hg+2) that reduced Vibrio fischeri light emission by 50 percent (EC50) were 3.43 + 0.83 and 0.66 + 0.01 mmol, respectively. Toxicity, as defined by EC50 values, were reduced for copper 17-20 percent by soil and peat fulvic acids and 9-20 percent by aquatic fulvic acids. Mercury toxicity was reduced 3.6-7.3 percent by soil and peat fulvic acids and 14-16 percent by aquatic fulvic acids. Humic acids had a greater effect than fulvic acids on copper toxicity (44-124 percent), while humic acids had approximately the same reduction of mercury toxicity (8-20 percent) as did fulvic acids (3.6-16 percent). Natural organic matter (NOM) isolated by reverse osmosis (92 percent recovery of NOM) had reduced toxicity effects on both copper and mercury that were similar to aquatic fulvic acid standards.
Field studies using the Microtox standard protocols for both pore waters and sediments at three contaminated sites gave highly variable results that were not coincident with sedimentary concentrations of various pollutants (mercury, methyl mercury, toxaphene, PCBs, mixed organic and heavy metal pollutants). Based on the field studies, it was decided not to pursue the laboratory studies of natural organic matter interactions with PAH and tributyl tin, as it was apparent that the effects could not be measured in field situations.
Fungal Subproject (Newell). The initial objective of this subproject was to "test whether Phaeosphaeria spartinicola [one of the two major species of ascomycetes (Kingdom Fungi) that are secondary-microbial producers in standing-decaying smooth cordgrass blades] can be used to detect anthropogenic perturbation of smooth-cordgrass saltmarshes." It was intended to examine the extents to which accumulation of living-fungal standing crops and rates of fungal sexual productivity would be impacted by toxic pollutants in saltmarshes. Living-fungal biomass would be determined as ergosterol content in decaying leaves, and sexual productivity as rates of ascospore expulsion from decaying leaves.
Southeastern saltmarshes with well documented, chronic input of anthropogenic toxicants, were chosen as study sites, along with both nearby and distant but environmentally comparable control sites. The first study of these contaminated sites was the LCP Chemical Superfund site in Brunswick, GA, where elemental mercury and PCBs were dumped into the marsh adjacent to the LCP Chemical chloroalkali plant. In addition to the LCP Superfund site, saltmarsh sites contaminated with chlorinated insecticide (toxaphene, Brunswick, GA) and PAHs and heavy metals (Charleston Harbor, Charleston, SC) were identified. Linkages were forged with scientists at Skidaway Institute of Oceanography to enable measurement of toxicants at our chosen locales. The central method used for measurement of living-fungal mass, the ergosterol assay, has been very thoroughly quality-control checked (Newell, 2001a). The ascospore-production method used has also been subjected to quality-control research as described in Newell (2001c).
Surprisingly, two basic fungal variables (living-fungal standing crop, fungal sexual productivity) did not exhibit negative impacts of toxic pollutants at any of the study sites. In fact, just the reverse was sometimes found?living-fungal crops and ascospore outputs were sometimes higher at the contaminated sites, which is believed to be a consequence of: (1) the high resistance of cordgrass ascomycetes to toxicants, and (2) positive response of cordgrass ascomycetes to anthropogenic nitrogen subsidy. A summary table of findings for living-fungal mass as percentages of controls follows:
| Heavy PCB/Hg
150% |
Moderate PCB/Hg
115% |
Unpolluted
100% |
| Heavy PAH/Cr
103% |
Light PAH/Cr
100% |
|
| Heavy SumTox
123% |
Light SumTox
121% |
Unpolluted
100% |
[where heavy PCB/Hg = 53/21 µg per g sediment; moderate PCB/Hg = 0.3/0.5 µg per g sediment; heavy PAH/Cr = 3360 ng/270 µg per g sediment; light PAH/Cr = 47 ng/89 µg per g sediment; Sum of toxaphene residues (SumTox), heavy = 6-7 µg per g sediment; light = 0.1-1.0 µg per g sediment.]
A major implication of these findings is that saltmarshes are exceptionally dangerous depots for toxic waste. Since ascomycetes are the predominant microbial secondary producers of these highly productive ecosystems, and their activities are not depressed by toxic pollution, the toxicants are likely to be readily passed along in the food chain by the marshgrass/fungal components of the ecosystem.
Macrophyte Subproject (Pennings). The overall goal of the project was to test the utility of several indicators of marsh health for identifying stresses caused by known or unknown pollutants. Field studies at heavily polluted sites in Brunswick, GA (a Superfund site polluted with mercury and PCBs, and a site polluted with toxaphene) and Charleston Harbor, SC (several sites polluted with metals and PAHs) have generally revealed little impact on indicators of marsh plant health (gas exchange, stress enzymes). Plant gas exchange was found to vary with tidal range, marsh elevation, and pore-water salinity. Consequently, future attempts to use this indicator as a measure of plant health must standardize for these environmental factors.
Microcrustacean Reproductive Potential Subproject (Kneib). This portion of the proposal focused on common key marsh species that form links connecting intertidal and subtidal components involved in the trophic-support function of tidal marshes. The principal goal was to determine the efficacy of using reproductive potential in three species of estuarine crustaceans as a measure of sublethal stress on the capacity of coastal salt marsh ecosystems to provide trophic support. Specific objectives of this research were to: (1) test the hypothesis that marsh systems stressed by pollutants support crustacean populations with less reproductive potential than healthy "systems", and (2) determine if the relationship between level of sublethal environmental stress and reproductive potential in these populations varied within the region of the South Atlantic Bight (SC - GA).
- Throughout the study, when adjusted for body size and season, there were no clear differences among sites with respect to brood size of any of the crustaceans examined in this study.
- Differences in average egg area (egg size) for tanaids were observed for stressed and reference sites in Georgia, but not South Carolina. Further analysis suggested that this finding was attributable to seasonal biases in the data sets rather than true difference in the reproductive potential of individuals living under different levels of environmental stress.
- Incidence of infection of grass shrimp by a parasitic isopod varied with season, but annually averaged higher in reference sites than in environmentally-stressed areas in both Georgia and South Carolina.
- There was a very clear difference between the abundance of tanaids and amphipods at stressed and reference sites in both Georgia and South Carolina. The presence of high densities of these crustaceans is probably a good indicator of a relatively clean and unstressed marsh site.
Journal Articles on this Report: 6 Displayed | Download in RIS Format
| Other project views: | All 39 publications | 15 publications in selected types | All 12 journal articles |
| Type | Citation | ||
|---|---|---|---|
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Alberts JJ, Takacs M, Pattanayek M. Influence of IHSS standard and reference materials on copper and mercury toxicity to Vibrio fischeri. Acta Hydrochimica et Hydrobiologica 2001;28(7):428-435. |
R825147 (Final) |
not available |
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Newell S, Wall VD. Response of saltmarsh fungi to presence of mercury and polychlorinated biphenyls at a Superfund site. Mycologia 1998;90(5):777-84. |
R825147 (Final) |
not available |
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Newell SY, Wall VD, Maruya KA. Fungal biomass in saltmarsh grass blades at two contaminated sites. Archives of Environmental Contamination and Toxicology 2000;38(3):268-273. |
R825147 (1998) R825147 (1999) R825147 (2000) R825147 (Final) |
not available |
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Newell SY. Multiyear patterns of fungal crop dynamics and fungal productivity within naturally decaying smooth cordgrass shoots. Limnology and Oceanography 2001;46(3):573-583. |
R825147 (2000) R825147 (Final) |
not available |
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Newell SY. Spore-expulsion rates and extents of blade occupation by ascomycetes of the smooth-cordgrass standing-decay system. Botanica Marina 2001;44(3):277-285. |
R825147 (1998) R825147 (1999) R825147 (2000) R825147 (Final) |
not available |
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Pennings SC, Moore DJ. Zonation of shrubs in western Atlantic salt marshes. Oecologia 2001;126(4):587-594. |
R825147 (1998) R825147 (1999) R825147 (2000) R825147 (Final) |
not available |
water, watersheds, sediments, marine, estuary, ecological effects, bioavailability, animal, organism, population, stressor, chemicals, toxics, PAHs, heavy metals, organics, indicators, aquatic, habitat, life cycle analysis, public good, conservation, environmental assets, environmental chemistry, biology, ecology, zoology, monitoring, analytical, measurement methods, southeast, Atlantic coast. , Ecosystem Protection/Environmental Exposure & Risk, Water, Geographic Area, RFA, Ecosystem/Assessment/Indicators, exploratory research environmental biology, Southeast, Mercury, Ecological Indicators, Ecological Effects - Human Health, Chemical Mixtures - Environmental Exposure & Risk, Ecological Effects - Environmental Exposure & Risk, Ecosystem Protection, Monitoring/Modeling, bacteria, aquatic, regional scale, South Atlantic Bight, cordgrass, salt marsh estuaries, monitoring, fish , aquatic ecosystems, estuarine ecosystems, health indicator, biodiversity
Relevant Websites:
http://www.arches.uga.edu/~rtkneib/
Progress and Final Reports:
1998 Progress Report
1999 Progress Report
2000 Progress Report
Original Abstract