Product Citations and Abstracts

On the evenings of 5 May, 10 May, 13 June and 11 July, 1983, truck-mounted ULV equipment was used to apply fenthion at a rate of 11 g/ha to control adult salt marsh mosquitoes at two sites. Meteorological conditions at the time of spray, spray droplet density, and droplet VMD were monitored. Mortality of caged Aedes taeniorhynchus and Culex quinquefasciatus was measured to evaluate spray effectiveness. Sand dunes and stands of pine trees affected wind speed and directions and reduced effectiveness during some sprays. When appropriate conditions prevailed, 100% mortality was achieved among caged mosquitoes placed up to 150 m from the spray source. These data provided the efficacy baseline for studies on nontarget species.

Clark, James R., James M. Patrick, Jr., James C. Moore and Jerrold Forester. 1986. Accumulation of Sediment-Bound PCBs by Fiddler Crabs. EPA/600/J-86/087. Bull. Environ. Contam. Toxicol. 36:571-578. (ERL,GB 533).

Polychlorinated biphenyls (PCBs) have been, and continue to be, an ecological problem because of their environmental persistence. In aquatic systems, PCBs sorb to organic matter, accumulate in sediments, and contaminate food chains. Because of the potential for causing reproductive impairment, PCBs in aquatic food chains pose a threat to human and other predators that consume fish and shellfish. Fiddler crabs accumulate PCBs from contaminated sediments and detritus and can transfer them to aquatic, avian, and terrestrial food webs when preyed upon by fishes, birds, and small mammals. The primary objective of our research was to characterize rates of PCB uptake and depuration by fiddler crabs in a simulated spoil bank habitat that contained PCBs in weathered sediment. Also, we examined whether the concentration of PCBs in substrates affected bioaccumulation by mixing PCB-laden sediments with clean sand. In a pilot study, we tested Uca pugilator, an inhabitant of relatively dry and sandy areas, and U. minax, which inhabits wetter and muddier substrates, to determine if species differ in PCB uptake and depuration rates.

Clark, J.R., L.R. Goodman, P.W. Borthwick, J.M. Patrick, Jr., J.C. Moore and E.M. Lores. 1986. Field and Laboratory Toxicity Tests with Shrimp, Mysids, and Sheepshead Minnows Exposed to Fenthion. In: Aquatic Toxicology and Environmental Fate: Ninth Volume, ASTM STP 921. EPA/600/D-86/036. T.M. Poston and R. Purdy, Editors. American Society for Testing Materials, Philadelphia, PA. Pp. 161-176. (ERL,GB 539). (Avail. from NTIS, Springfield, VA: PB86-158649)

We conducted a series of laboratory pulse-exposure experiments to model short-term field exposures of two representative estuarine crustaceans, Penaeus duorarum and Mysidopsis bahia, to the organophosphate insecticide fenthion. These tests established acutely lethal and nonlethal concentrations during pulse exposures. The data are necessary for interpretation of responses of test animals in the field when fenthion concentrations changed rapidly with time. The toxicity of fenthion to caged pink shrimp, mysids, and sheepshead minnows (Cyprinodon variegatus) was determined in the field following two aerial applications separated by 72 h, to control adult saltmarsh mosquitoes. At one estuarine site, initial concentrations of fenthion in water were 1.5 µg/L following Spray 1 and 0.29 µg/L after Spray 2. Within 12 to 24 h, however, fenthion was not detectable (< 0.01 µg/L) because of rapid tidal flushing and high dilution at this site. Although initial exposures approached or exceeded laboratory 24-h LC50s for pink shrimp (0.40 µg/L) and mysids (0.42 µg/L), no mortality occurred among caged animals. At a second site along a residential saltwater canal with limited tidal flushing and dilution, initial concentrations of fenthion were 2.6 µg/L (Spray 1) and 0.5 µg/L (Spray 2). Within 12 to 24 h post-spray, fenthion decreased to 0.4 µg/L (Spray 1) and 0.14 µg/L (Spray 2) and continued to diminish during the next 48 to 72 h. These concentrations approximated the 48- and 72-h LC50s for pink shrimp (0.22 µg/L and 0.l5 µg/L) and mysids (0.37 µg/L and 0.18 µg/L). All exposure concentrations were three orders of magnitude below the 24-h LC50 for sheepshead minnows (1900 µg/L) and no mortality occurred among caged fish. By deploying caged pink shrimp and mysids daily, before and after each spray, in situ exposure regimes varied for each group and resulted in responses among caged test populations that ranged from no observed effect to 100% mortality. The responses of caged pink shrimp and mysids exposed to slowly changing concentrations of fenthion in the field were similar to what would have been predicted based on laboratory tests that established 24-, 48-, and 72-h LC50s. Laboratory pulse-exposure tests were predictive of no-effect and effect pulse exposures in the field. These comparisons demonstrated that predictions of fenthion toxicity based on laboratory test results were valid when field and laboratory exposure regimes were similar.

Clark, James R., James M. Patrick, Jr., Douglas P. Middaugh and James C. Moore. 1985. Relative Sensitivity of Six Estuarine Fishes to Carbophenothion, Chlorpyrifos, and Fenvalerate. EPA/600/J-85/336. Ecotoxicol. Environ. Saf. 10(3):382-390. (ERL,GB 541). (Avail. from NTIS, Springfield, VA: PB86-171634)

The acute toxicity (96-hr LC50) of carbophenothion, chlorpyrifos, and fenvalerate to six estuarine fishes was determined in flow-through laboratory tests. The atherinid fishes (Menidia menidia, M. peninsulae, M. beryllina, and Leuresthes tenuis) consistently were among the most sensitive species tested and were similar to each other in their sensitivity to pesticides. The sensitivity of sheepshead minnows (Cyprinodon variegatus) to carbophenothion was the same as that of the atherinids. For fenvalerate, the sheepshead minnow LC50 was an order of magnitude greater than that of the most sensitive atherinid, whereas the LC50 for chlorpyrifos and sheepshead minnows was two orders of magnitude greater. Gulf toadfish (Opsanus beta) were the least sensitive fish tested with carbophenothion and chlorpyrifos and their 96-hr LC50 for fenvalerate ranked between the LC50 for sheepshead minnows and atherinids. Test results were compared to acute toxicity data for other estuarine fishes and invertebrates.

Clark, James R., Patrick W. Borthwick, Larry R. Goodman, James M. Patrick, Jr., Emile M. Lores and James C. Moore. 1987. Comparison of Laboratory Toxicity Test Results with Responses of Caged Estuarine Animals Exposed to Fenthion in the Field. EPA/600/J-87/063. Environ. Toxicol. Chem. 6:151-160. (ERL,GB 545). (Avail. from NTIS, Springfield, VA: PB87-213237)

Acute, lethal effects of fenthion (an organophosphate insecticide) on mysids (Mysidopsis bahia), grass shrimp (Palaemonetes pugio), pink shrimp (Penaeus duorarum), and sheepshead minnows (Cyprinodon variegatus) were determined in laboratory tests and after field applications. Exposure at four field sites ranged from short-term exposures (12 h or less) of rapidly decreasing fenthion concentrations to extended intervals (more than 72 h) with slowly increasing or decreasing fenthion concentrations. Laboratory-derived LC50s provided a reliable benchmark for predicting acute, lethal effects of fenthion on caged animals in the field when exposures persisted for 24 h or more but overestimated the toxicity for exposures less than 24 h. Laboratory pulse-exposure tests with rapidly changing concentrations for 12 h were predictive of nonlethal and lethal effects observed for short-term field exposures.

Clark, James R., James M. Patrick, Jr., James C. Moore and Emile M. Lores. 1987. Waterborne and Sediment-Source Toxicities of Six Organic Chemicals to Grass Shrimp (Palaemonetes pugio) and Amphioxus (Branchiostoma caribaeum). EPA/600/J-87/141. Arch. Environ. Contam. Toxicol. 16:401-407. (ERL,GB 575). (Avail. from NTIS, Springfield, VA: PB88-149034)

Grass shrimp (Palaemonetes pugio) were exposed to either waterborne or sediment-source concentrations of fenvalerate, cypermethrin, 1,2,4-trichlorobenzene (TCB), tributyltin oxide (TBTO), triphenyltin oxide, and di-n-butylphthalate in static or flow-through test systems. Similarly, amphioxus (Branchiostoma caribaeum) were tested with fenvalerate, TCB, and TBTO. The LC50 and no-effect and 100% mortality concentrations are reported from 96-hr and 10-day tests. The toxicity of contaminated sediments could be explained by chemical partitioning into overlying or interstitial water. Amphioxus is not recommended as a routine test species because of (1) difficulty in distinguishing severely affected from dead animals, (2) inability to determine the status of burrowed animals without disrupting sediment, (3) their relative lack of sensitivity in acute exposures to toxic chemicals, and (4) difficulty in routine collection of sufficient numbers of animals. Grass shrimp, however, are useful as an epibenthic test species for waterborne and sediment-source toxicants.

Clark, J.R., P.W. Borthwick, L.R. Goodman, J.M. Patrick, Jr., E.M. Lores and J.C. Moore. 1987. Effects of Aerial Thermal Fog Applications of Fenthion on Caged Pink Shrimp, Mysids, and Sheepshead Minnows. EPA/600/J-87/313. J. Am. Mosq. Control Assoc. 3(3):466-472. (ERL,GB 602). (Avail. from NTIS, Springfield, VA: PB88-196068)

Mosquito control applications of fenthion by aerial thermal fog equipment were studied at two sites in Collier County, FL, for sprays that occurred on 20 and 23 June 1984. Acute, lethal effects of fenthion deposited in these estuarine habitats were assessed for caged pink shrimp (Penaeus duorarum), mysids (Mysidopsis bahia), and sheepshead minnows (Cyprinodon variegatus). At Site 1, along a bay with substantial dilution and tidal mixing, fenthion concentrations of 1.5 µg/l and 0.29 µg/l were recorded immediately after both sprays. Concentrations decreased to less than or equal to 0.020 µg/l 12 h post-spray and no mortality was observed for caged pink shrimp and mysids. Site 2 was along a residential canal system that offered limited dilution and mixing. Measurable concentrations (> 0.038 µg/l) of fenthion persisted at this site for 4 days. Fenthion concentrations in surface waters were toxic to caged pink shrimp and mysids after both sprays; maximum concentrations were 2.6 µg/l and 0.51 µg/l. Caged sheepshead minnows were not affected by the sprays at either site.

Clark, James R. and James M. Patrick, Jr. 1987. Toxicity of Sediment-Incorporated Drilling Fluids. EPA/600/J-87/312. Mar. Pollut. Bull. 18(11):600-603. (ERL,GB 607). (Avail. from NTIS, Springfield, VA: PB88-196076)

The 24, 96, or 168-h LC50s of four used drilling fluids or barite incorporated into sediment were determined in toxicity tests with lancelets (Branchiostoma caribaeum), a benthic chordate. The number of lancelets that did not burrow into contaminated sediments was used to calculate EC50s at the same times that LC50s were determined. Observations of the burrowing behavior allowed quantitation of effects after 24-h exposures to each of the drilling fluids whereas lancelet mortality was sufficient to calculate 24-h LC50s for only one drilling fluid. Drilling fluids were less toxic to lancelets when incorporated into sediments than to mysids (Mysidopsis bahia) or benthic invertebrate communities in water-column exposures.

Clark, James R., Larry R. Goodman, Patrick W. Borthwick, James M. Patrick, Jr., Geraldine M. Cripe, Paul H. Moody, James C. Moore and Emile M. Lores. 1989. Toxicity of Pyrethroids to Marine Invertebrates and Fish: A Literature Review and Test Results with Sediment-Sorbed Chemicals. EPA/600/J-89/040. Environ. Toxicol. Chem. 8(5):393-401. (ERL,GB 618). (Avail. from NTIS, Springfield, VA: PB90-103599)

Data on the acute and chronic toxicities of permethrin, cypermethrin and flucythrinate to marine invertebrates and fish are reviewed. Generally, crustaceans are more sensitive than fish; oysters are comparatively insensitive. The mysid Mysidopsis bahia consistently is among the most sensitive crustaceans tested, with 96-h LC50s of less than 0.02 µg/L for permethrin and of less than 0.01 µg/L for fenvalerate, cypermethrin and flucythrinate. The potential for chronic toxicity to fish is minimal for permethrin, moderate for fenvalerate and relatively great for flucythrinate. Laboratory toxicity tests were conducted with sediment-source fenvalerate and cypermethrin under static and flow-through conditions to determine the degree of contamination necessary to achieve acute lethal effects on mysids, grass shrimp (Palaemonetes pugio) and pink shrimp (Penaeus duorarum). Mortality was observed in test animals only in systems where the concentrations of sediment-source pyrethroids were sufficient to establish lethal concentrations in the overlying water through sediment/water partitioning. For fenvalerate, lethal effects occurred at nominal sediment concentrations of 0.1 mg/kg (static and flow-through) for mysids and grass shrimp and at 10 mg/kg for pink shrimp. Nominal sediment concentrations of cypermethrin of 0.1 mg/kg (static) or 0.1 mg/kg (flow-through) resulted in mortality in mysids and grass shrimp, whereas 1.0 mg/kg was the only test concentration that caused mortality in pink shrimp in the static and flow-through test systems. The correspondence between aqueous concentrations and LC50s for test animals demonstrated the importance of quantitating the bioavailable portion of pyrethroids in field samples to characterize accurately the environmental risk associated with pyrethroid runoff after agricultural applications.

Clark, James R. and John M. Macauley. 1990. Comparison of the Seagrass Thalassia testudinum and Its Epiphytes in the Field and in Laboratory Test Systems. In: Plants for Toxicity Assessment. ASTM STP 1091. EPA/600/J-90/365. W. Wang, J.W. Gorsuch, and W.R. Lower, Editors. American Society for Testing and Materials, Philadelphia, PA. Pp. 59-68. (ERL,GB 629). (Avail. from NTIS, Springfield, VA: PB91-163790)

Thalassia testudinum and associated epiphytes from field plots were compared with plants from laboratory microcosms to determine if laboratory observations obtained from plants undergoing seasonal growth patterns were characteristic of plants in natural systems. The measurements selected for characterizing Thalassia health were chlorophyll and protein content of leaves and carbohydrate content of rhizomes. For epiphytes, we measured standing crop and chlorophyll content. Mean values for field and laboratory data were statistically analyzed for two experiments conducted over six-week intervals and for one experiment extended to twelve weeks. Thalassia plants in the laboratory followed similar trends of field plants during the six-week experiments, but the laboratory plants differed significantly from field plants at twelve weeks. Chlorophyll content of epiphyte communities colonizing Thalassia leaves was significantly different in the laboratory compared to field communities, but trends from test initiation to the six-week sampling were consistent between field measurements and laboratory test systems.

Clark, James R. 1989. Field Studies in Estuarine Ecosystems: A Review of Approaches for Assessing Contaminant Effects. In: Aquatic Toxicology and Hazard Assessment: 12th Volume, ASTM STP 1027. EPA/600/D-89/255. U.M. Cowgill and L. R. Williams, Editors. American Society for Testing and Materials, Philadelphia, PA. Pp. 120-133. (ERL,GB 638). (Also avail. from NTIS, Springfield, VA: PB90-129586)

A sampling strategy designed around contaminant source (agricultural runoff, direct discharge) and fate (solubles, particulates, sediments) and the hydrodynamics of the system studied is required to characterize the exposure of estuarine biota to contaminants. Field data obtained on contaminant effects should be applicable to risk assessment in order to verify approaches to predicting contaminant fate and effects in estuarine systems. Only through systematic evaluations of field and laboratory exposure-response relationships will be able to quantify the limits of applicability of laboratory data used for ecological risk assessment. Survival of caged test animals at fieldl test sites provides data for direct comparison with laboratory toxicity test results. Coupling survival and other effects data from caged animal studies with assessments of stocks and dynamics of populations of the same or a related species at the field site may allow extrapolation from simple laboratory and field test results (acute or chronic) to more complex and ecologically significant endpoints. This paper presents examples of various approaches to contaminant problems in estuaries and discusses their applications to risk assessment procedures.

Clark, James R., Richard B. Coffin, John M. Macauley and Jerry R. Hoff. 1990. Results of Environmental Monitoring in Prince William Sound Following Fertilizer Additions to Enhance Oil Degradation. Paper 90-22.4. In: Proceedings: 83rd Air and Waste Management Association Annual Meeting, 24-29 June 1990, Pittsburgh, PA. Vol. 1. Harold Englund, Editor. Air and Waste Management Association, Pittsburgh, PA. 29 p. (ERL,GB 700). (R149)

Nutrients applied to Prince William Sound oiled shorelines to stimulate bacterial growth and thus enhance oil degradation could also stimulate algal or bacterial blooms if washed into adjacent nearshore waters. Further, the consequence of oil release could result in the bioaccumulation of oil or its metabolites by marine biota. We monitored for changes in ammonia, nitrite, nitrate, and phosphate concentrations, abundance and productivity of bacteria, and abundance and productivity of algae. No enhanced nutrient concentrations were observed, nor were significant, sustained enhancements of planktonic bacteria or algae recorded. We deployed caged mussels (Mytilus edulis) for monitoring tissue residues of total polynuclear aromatic hydrocarbons. No differences in residues were observed from analyses of tissue samples from treated and reference areas.

Clark, James R. and John L. Noles. 1993. Contaminant Effects in Marine/Estuarine Systems: Field Studies and Scaled Simulations. In: Aquatic Mesocosm Studies in Ecological Risk Assessment. EPA/600/J-94/109. Robert L. Graney, James H. Kennedy, and John H. Rodgers, Editors. CRC Press, Boca Raton, FL. Pp. 47-60. (ERL,GB 731). (Avail. from NTIS, Springfield, VA: PB94-155488)

Attempts to obtain field data for risk ssessment of contaminants released into marine/estuarine systems can be complicated by a number of interrelated factors such as: complex circulation and mixing patterns, diverse stratification forces, dynamic short-term changes as well as seal movements of biota, and the ecosystem's physical scale. Tests conducted in simulated ecosystems are subject to constraints that restrict the effect of physical forces, limit physical scale of the test, and introduce biases from chemical partitioning and processing along the walls of the test system. These constraints restrict the broad application of test results as a model of dynamic marine systems. Through selected examples from literature and ongoing studies, we provide illustrations of how contaminant effects are studied at the individual population, and community level in the field and/or in simulated ecosystems, such as mesocosms. We discuss marine-environment field studies and simulated field studies that measure contaminant effects with respect to exposure-response relationships, food-web interactions, competition/colonization studies, and selected aspects of nutrient cycling. Based on results to date, we conclude that: (1) successful field studies must focus on selected endpoints fundamental to our understanding of contaminant effects, and (2) endpoints studied in simulated ecosystems must be representative of key structural and/or functional factors of the system of interest.

Clark, James R. 1991. Mosquito Control Pesticides: Adverse Impacts to Freshwater Aquatic and Marine Organisms. In: Mosquito Control Pesticides: Ecological Impacts and Management Alternatives. EPA/600/A-92/122. Thomas C. Emmel and John C. Tucker, Editors. Scientific Publishers, Gainesville, FL. Pp. 33-39. (ERL,GB 747). (Avail. from NTIS, Springfield, VA: PB92-195890)

Most toxicity information available for evaluating potential effects of mosquito control chemicals on non-target aquatic biota comes from acute lethality tests of 24- to 96-hr duration. These studies generally show that insecticides are more toxic to aquatic invertebrates than fishes. Crustaceans, in particular, are extremely sensitive to mosquito control insecticides, perhaps a result of their close phylogenetic relationships with insects. Effects of longer-term exposures on survival and growth studies that quantify other sublethal effects are available only for selected, standard laboratory test species for some chemicals. Field studies conducted by our laboratory following operational insecticide applications have shown that exposures can be of shorter duration and of lesser concentration than those used for worst-case scenarios in screening-level environmental risk assessments. However, long-term effects of repeated applications of the same chemical or cumulative effects of multiple-chemical treatments have not been adequately assessed in the field.

Clark, J.R. and C.R. Cripe. 1993. Marine and Estuarine Multi-Species Test Systems. In: Handbook of Ecotoxicology, Volume One. EPA/600/A-94/033. Peter Calow, Editor. Blackwell Scientific Publications, Oxford, England. Pp. 227-247. (ERL,GB 758). (Also Avail. from NTIS, Springfield, VA: PB94-155371)

Marine and estuarine habitats have a great deal of temporal and spatial variability due to the highly complex physical and chemical components that interact with biological components to yield dynamic ecosystems. Salinity differences among component water masses represent one example of the many factors affecting the distribution of the biota within marine and estuarine systems. Salinity differences can range from a few parts per thousand to greater than fifty parts per thousand and commonly establish gradients within an estuary that change over time. This variability sometimes results from predictable and periodic short-term, tidal cycles and longer-term, seasonal changes in physical and chemical forces, such as freshwater inflow, temperature, and wind patterns operating within the ecosystem and at the system boundaries. Other, less predictable forces, such as daily winds, storm events, human intervention, etc., also contribute to temporal and spatial variability within marine systems over short-term and long-term durations and small and large areas. Understanding the effects of pollutants on these ecosystems requires tools that present defined ecosystem boundaries, control and manipulation of many environmental factors and minimal temporal and spatial variability or defined limits for change. These investigation and testing tools, commonly known as microcosms and mesocosms, offer a wide range of complexity in species and ecological make up and sophistication in materials and mechanical engineering for addressing ecotoxicological problems. In this chapter, we provide examples of various types of multispecies test systems that have been used in marine and estuarine studies and discuss their role in ecotoxicological assessments.

Clark, James R., Michael A. Lewis and Anthony S. Pait. 1993. Pesticide Inputs and Risks in Coastal Wetlands. EPA/600/J-94/017. Environ. Toxicol. Chem. 12(12):2225-2233. (ERL,GB 866). (Avail. from NTIS, Springfield, VA: PB94-140647)

Coastal wetland habitats may receive pesticide inputs indirectly from agricultural and forest control of weeds and insects in upland drainage areas; indirectly or directly from weed, insect, and biofouling control from development of adjacent lands for agricultural, recreational or residential uses; and directly from control activities practiced within wetlands for protection of public health or for nuisance abatement. Persistent and bioaccumulative pesticides used at upland sites have threatened coastal wetland biota. For some more biodegradable contemporary pesticides, concerns for ecological impact are more a function of the proximity of the site of application relative to the wetland, and time available for degradation and sorption. In addition, the rate and extent of localized mixing, flushing, and stratification within the wetland can greatly affect exposure concentrations and durations for wetland biota. The short-term, direct toxic effects of pesticides on aquatic biota inhabiting coastal wetlands have been characterized in laboratory and field studies; however, the cumulative and indirect effects of repeated exposure to multiple chemicals at sublethal concentrations is a major research need.

Clark, James R., Donald S. Cherry and John Cairns. 1982. Food Quality of Aufwuchs from Artificial Streams Receiving Low Levels of Perturbations. Water Resour. Bull. 18(5):761-767. (ERL,GB X391).

Protein, carbohydrate, and organic content of Aufwuchs samples from artificial streams dosed separately with chlorine copper, or dextrose were altered by changes in the taxonomic composition or physiological condition of the community. Protein content increased as community composition shifted toward a dominance by blue-green algae or heterotrophs. Bluegreens or cyanobacteria were dominant most often in Aufwuchs developing under copper or chlorine treatments and when water temperatures approached the seasonal maximum (22.8 C-25.8 C), while heterotrophs proliferated in the dextrose-enriched stream. Due to the associated extracellular mucilage, carbohydrate content also tended to be higher when blue-green algae or bacteria were abundant. However, carbohydrate content decreased in communities developing under chlorine or copper treatments at low or moderate temperatures (3 C-22.8 C), indicating a utilization of stored photosynthetic products to adapt to the stress. The organic content of Aufwuchs was related to the extent of mucilage production and the tendency of the community to accumulate detritus and suspended inorganic sediment. Protein and carbohydrate estimates were significantly correlated with dry weight and ash-free dry weight, a result of the copious extracellular mucilage associated with rapidly growing blue-greens and other bacteria. Estimates of Aufwuchs food quality are important in evaluating the impact of pollutants on higher trophic levels; however, the tendency of change with both taxonomic shifts and physiological adaptations tends to confound interpretations for water quality assessment.

Clark, James R., Dave Devault, Robert J. Bowden and Joseph A. Weishaar. 1984. Contaminant Analysis of Fillets from Great Lakes Coho Salmon, 1980. J. Great Lakes Res. 10(1):38-47. (ERL,GB X484).

Analyses of coho salmon from each of the Great Lakes by a single laboratory produced residue data on the accumulation of environmental contaminants which have been banned, severely restricted, or are currently permitted in the basin. Coho salmon from Lake Superior contained only trace amounts or low levels of most toxic substances quantified; Lake Erie fish were contaminated with low levels of a number of pesticides and industrial compounds; relatively higher residues were detected in coho salmon from Lake Huron and Lake Michigan; and the highest concentrations for a number of compounds were found in fillets from coho from Lake Ontario. Contaminant concentrations in migratory coho salmon indicate open lake contaminant problems rather than point source or nearshore conditions. Tissue residues were less than USFDA action levels, used by many agencies in assessing the severity of fish contaminant problems. Only mirex concentrations in fish collected from Lake Ontario exceeded a USFDA action level. The data reported in this study generally agree with recent findings from individual state contaminant monitoring programs. Problems with varying analytical and sampling techniques preclude direct comparisons with previously published data of other studies.

Ecological indicators can be defined as relatively simple measurements that relay scientific information about complex ecosystems. Such indicators are used to characterize risk in ecological risk assessment and to mark progress toward resource management goals. In late 1997, scientists from the U.S. Environmental Protection Agency and from the Chemical Manufacturers Association (CMA) held a workshop to explore opportunities for collaborative research and scientific exchange on the development and application of ecological indicators. Several scientific challenges were identified as they relate to problem formulation, exposure and effects assessment, and risk characterization. Chief among these were a better understanding of multiple stressors (both chemical and non-chemical), characterization of reference sites and natural variability, extrapolation of measures to ecologically relevant scales, development of comprehensive, ecosystem-based models that incorporate multiple stressors and receptors, and a consistent system for evaluating indicators.

Moore, James C., E.M. Lores, James R. Clark, P. Moody, J. Knight and J. Forester. 1985. Effects of Ground ULV Applications of Fenthion on Estuarine Biota: II. Analytical Methods and Results. EPA/600/J-85/461. J. Fla. Anti-Mosquito Assoc. 56(2):62-68. (ERL,GB 523b). (Avail. from NTIS, Springfield, VA: PB87-152773)

Methods of analyses were validated for quantitating fenthion residues in samples from two salt marsh sites subjected to ground ultra-low volume sprays. Concentrations of these residues were followed from the water's surface, through the water column and onto the sediment. For all sprays, the highest concentration, detected in the upper portion of the water column, was 0.48 µg/l and occurred within the first hour after spraying. Detectable concentrations (>0.010 µg/l) of fenthion persisted in the water for up to 24 h. Fenthion did not accumulate to a detectable level (0.010 µg/g) in tissues of caged shrimp or fish.

Price, W. Allen, John M. Macauley and James R. Clark. 1986. Effects of Drilling Fluids on Thalassia testudinum and Its Epiphytic Algae. EPA/600/J-86/334. Environ. Exp. Bot. 26(4):321-330. (ERL,GB 555). (Avail. from NTIS, Springfield, VA: PB87-178661)

A flow-through microcosm system was developed to assess the potential influence of drilling fluids on Thalassia testudinium and its epiphytic algae. Two treatments (drilling fluid and a montmorillonite clay) and a control were used for seven tests: two 10-day, 200 µl/l exposures; two 10-day, 1000µl/l; and three six-week, 190 µl/l. Six-week exposure to drilling fluid reduced epiphyte biomass (measured as ash free dry weight/cm2), but surviving algae did not differ (measured as chlorophyll a/g epiphyte ash free dry weight) from controls. Thalassia productivity (carbon uptake and growth rate) was reduced by 10-day exposure to drilling fluid concentrations of 200 µl/l and 1000 µl/l. Thalassia productivity was reduced by drilling fluid exposure in summer and fall but not in spring. The variation in response is attributed to seasonal changes in Thalassia allotment and storage of carbohydrates. The effect of montmorillonite clay exposure varied inconsistently among all tests for both Thalassia and epiphytes.

Macauley, John M., James R. Clark and W. Allen Price. 1988. Seasonal Changes in the Standing Crop and Chlorophyll Content of Thalassia testudinum Banks ex Konig and Its Epiphytes in the Northern Gulf of Mexico. EPA/600/J-88/280. Aquat. Bot. 31(3-4):277-287. (ERL,GB 611). (Avail. from NTIS, Springfield, VA: PB89-209803)

The seasonal cycles for standing crop and chlorophyll content of Thalassia testudinum and its epiphytes are described from monitoring data collected at a study site in Santa Rosa Sound, northwestern Florida, from December 1983 through March 1987. Water temperature correlated more highly with standing crop and chlorophyll measurements than did salinity or incident light. The seasonal cycle described for Thalassia was positively correlated with temperature whereas epiphyte standing crop was negatively correlated with water temperature.

Heitmuller, P.T. and James R. Clark. 1989. Bioaccumulation of 1,2,4-Trichlorobenzene from Food and Water Sources by Spot (Leiostomus xanthurus). In: Aquatic Toxicology and Hazard Assessment: 12th Volume, ASTM STP 1027. EPA/600/D-89/256. U.M. Cowgill and L.R. Williams, Editors. American Society for Testing and Materials, Philadelphia, PA. Pp. 261-269. (ERL,GB 642). (Also avail. from NTIS, Springfield, VA: PB90-129594)

Contaminated food was prepared by exposing pink shrimp (Penaeus duorarum) to 10 µg/L of radiolabeled (14C) 1,2,4-trichlorobenzene (TCB) for 12 days; whole body concentration of TCB in the exposed shrimp was 0.59 µg/g. Juvenile spot (Leiostomus xanthurus), a marine fish, were then fed the TCB-contaminated shrimp at a daily ration of 10% body weight for 28 days, and they accumulated < 0.05 µg/g TCB (detection limits). Spot exposed to 10 µg/L TCB in water for 28 days and fed uncontaminated food bioconcentrated TCB approximately 100 times the aqueous exposure concentration. Equilibrium was attained in these fish within 7 days and depurated TCB to concentrations < 0.1 µg/g within 24 h after being placed in TCB-free water. Spot, exposed simultaneously to contaminated food and water described above, bioaccumulated TCB equal to the aqueous exposure treatment. Pharmacokinetic uptake and depuration rate constants were used to compare the potential for spot to bioaccumulate TCB, a moderately lipophilic compound, to that for chlordecone (Kepone), a highly lipophilic compound. Our results were also compared to those from a TCB bioaccumulation study with freshwater species; both studies indicated that TCB was moderately accumulated from contaminated water and that accumulation from contaminated food was negligible.

Macauley, John M., James R. Clark and Amy R. Pitts. 1990. Use of Thalassia and Its Epiphytes for Toxicity Assessment: Effects of a Drilling Fluid and Tributyltin. In: Plants for Toxicity Assessment. ASTM STP 1091. EPA/600/J-90/380. W. Wang, J.W. Gorsuch, and W.R. Lower, Editors. American Society for Testing and Materials, Philadelphia, PA. Pp. 255-266. (ERL,GB 666). (Avail. from NTIS, Springfield, VA: PB91-163931)

Concurrent 12-week laboratory and field studies were conducted to determine toxicity of the suspended particulate phase (SPP) of drilling fluid to Thalassia testudinum and its epiphytes. Test systems were treated once per week to achieve nominal concentrations of 100 mg/L SPP . Chlorophyll content of Thalassia leaves and epiphyte biomass and chlorophyll content were monitored during each test. Laboratory exposures were conducted in 7-L, flow-through (7 L/h) microcosms consisting of Plexiglass cylinders containing intact cores of Thalassia from a local seagrass bed. Field exposures were conducted in water-tight plexiglass chambers (2 m x 2 m x 1.5 m) placed over test plots in a seagrass bed for 24 h during SPP additions. The chamber base was buried several cm into the sediment to minimize water exchange. Drilling fluid exposure had no significant effect on chlorophyll a or b content of Thalassia leaves in laboratory or field tests. Epiphyte biomass was reduced after 6 weeks of intermittent exposure to SPP in laboratory and field tests. After 12 weeks, epiphyte biomass had increased to densities similar to control values. Tributyltin chloride (TBT-Cl) was tested only in laboratory systems, using weekly treatments for six weeks. Nominal test concentrations ranged from 0.2 to 50 µg/L. Leaf protein and rhizome carbohydrate content of Thalassia were employed as effect measures in the TBT-Cl test. Leaf concentrations of chlorophyll a and b were not affected by exposure to TBT-Cl at nominal concentrations < or = 50 µg/L. Leaf protein and rhizome carbohydrate concentrations were reduced by exposure to 50 µg/L TBT-Cl. Epiphyte biomass was reduced after exposure to 50 µg/L TBT-Cl for 6 weeks; concentrations Lindstrom, Jon E., Roger C. Prince, James R. Clark, Matthew J. Grossman, Thomas R. Yeager, Joan F. Braddock and Edward J. Brown. 1991. Microbial Populations and Hydrocarbon Biodegradation Potentials in Fertilized Shoreline Sediments Affected by the T/V Exxon Valdez Oil Spill. Appl. Environ. Microbiol. 57(9):2514-2522. (ERL,GB 748).

The effort to clean up the T/V EXXON Valdez oil spill in Prince William Sound included the use of fertilizers to accelerate natural microbial degradation of stranded oil. A program to monitor various environmental parameters associated with this technique took place during the summer of 1990. Microbiological assays for numbers of heterotrophic and oil degrading microbes and their hydrocarbon mineralization potentials were performed in support of this program. Fertilizer addition resulted in higher hexadecane and phenanthrene mineralization potentials on treated plots compared to untreated reference plots. Microbial numbers in treated and reference surface sediments were not significantly different immediately following the first nutrient application in May 1990. However, subsurface treated sediments had higher numbers of hydrocarbon degraders than the reference sediments shortly after treatment. The second application of fertilizer, later in summer, resulted in surface and subsurface increases in numbers of hydrocarbon degraders with respect to reference sediments at two of the three study sites. Elevated mineralization potential coupled with increased numbers of hydrocarbon degraders indicate that natural hydrocarbon biodegradation was enhanced but these microbiological measurements alone are not sufficient to determine in situ rates of crude oil biodegradation.

Moore, James C., James C. Dukes, James R. Clark, Janice Malone, Charles F. Hallmon and Phillip G. Hester. 1993. Downwind Drift and Deposition of Malathion on Human Targets from Ground Ultra-Low Volume Mosquito Sprays. EPA/600/J-94/015. J. Am. Mosq. Control Assoc. 9(2):138-142. (ERL,GB 775). (Also avail. from NTIS, Springfield, VA: PB94-140654)

Malathion (S-[1,2-bis(etyhoxycarbonyl)ethyl] phosphoro-dithioate, Cythion® , American Cyanamid Company) is applied by aircraft and trucks in Florida to control mosquitoes. Spray effectiveness has been determined by mortality of caged mosquitos, field measures of mosquito abundance or activity and analysis of droplets collected on slides. Undesirable ecological effects of malathion used for mosquito control purposes are commonly associated with misapplication or are limited to short-term effects on sensitive crustaceans and insects (Mulla et al. 1979). Since malathion is acutely toxic to mammals in doses generally ranging from 200 to 1,000 mg/kg (US DHHS 1991), human exposures during mosquito control operations are considered inconsequential. Increasing public awareness and concern over personal and environmental exposures to mosquito control pesticides requires that malathion deposition be quantified. The objectives of this research were: 1) to determine the amount of malathion deposited on human subjects located at various distances from the path of a spray vehicle during typical spray conditions, 2) to determine the amount of malathion deposited at ground level at various distances from the spray vehicle, and 3) to compare the deposition of malathion onto body surfaces with published dermal LD50 values for mammalian toxicity.

Flemer, David A., James R. Clark, Roman S. Stanley, Charles M. Bundrick and Gayle R. Plaia. 1993. Importance of Physical Scaling Factors to Benthic Marine Invertebrate Recolonization of Laboratory Microcosms. EPA/600/J-94/114. Int. J. Environ. Stud. 44:161-179. (ERL,GB 804). (Also avail. from NTIS, Springfield, VA: PB94-155538)

Five laboratory studies of benthic macroinvertebrate recolonization were conducted for six-week periods to evaluate the effects of physical scaling factors (i.e. microcosm size, seawater flow rates and sediment depth) on benthic community structure. Design variables included four open-faced acrylic containers of size-7, -12, -20, and -32 cm/side; seawater flow rate--approximately 0.7 or 1.6 liters/min; and sediment depth of 2.5 or 5.0 cm. Response variables included: total number of organisms (TNO), and taxa (TNT) and dominant taxa. Effects of seawater flow rates were more apparent than those related to microcosm size and sediment depth. Both TNO and TNT gave significant positive responses to increasing flow. Size effects were non-linear; size-20 microcosms tended to average more organisms than size-32 but effects were often not significant (P>0.05). Size-20 microcosms averaged higher numbers of taxa than size-32 and responses were usually significant (P<0.05). Dominant taxa in these experiments were the tunicates, Molgula sp. And Didemnum sp., and amphipod, Corophium acherusicum, a bryozoan, Bugula neritina, and the bivalves, Cumingia tellinoides and Laevicardium mortoni. Below the fourth rank, dominant taxa varied greatly among treatments. In a number of cases, individual taxa were in sufficient abundance to test for taxa-specific effects. Relatively rare taxa (e.g. taxa containing 1 to 7 individuals within an individual experiment) frequently accounted for 60% of the total number of taxa. Statistical power analysis based on a representative data set of non-mobile macroinvertebrates which provided an increased number of degrees of freedom detected a 20% difference from the means of response variables but a doubling or larger sample size would be required to detect a 10% difference at a power >or= 0.9 for an alpha=0.05. These results help provide a basis for setting minimum experimental unit parameters and should lead to cost savings through physical scale reduction (depth of sediment and surface area) and less time to process smaller volumes of sediment and generation of smaller volumes of waste water.

Scott, Geoffrey I., Michael H. Fulton, David W. Moore, Edward F. Wirth, G. Thomas Chandler, Peter B. Key, James W. Daugomah, Erich D. Strozier, John Devane, James R. Clark, Michael A. Lewis, Dana B. Finley, Walter Ellenberg and Karl J. Karnaky, Jr. 1999. Assessment of Risk Reduction Strategies for the Management of Agricultural Nonpoint Source Pesticide Runoff in Estuarine Ecosystems. EPA/600/J-99/. Toxicol. Ind. Health. 15(1-2):200-213. (ERL,GB X946).

Agricultural nonpoint source (NPS) runoff may result in significant discharges of pesticides, suspended sediments, and fertilizers into estuarine habitats adjacent to agricultural areas or downstream from agricultural watersheds. Exposure of estuarine fin fish and shellfish to toxic levels of pesticides may occur, resulting in signifcant declines in field populations. Integrated pest management (IPM), best management practices (BMP), and retention ponds (RP) are risk management tools that have been proposed to reduce the contaminant risk from agricultural NPS runoff into estuarine ecosystems. Field studies were conducted at three sites within coastal estuarine ecosystems of South Carolina (SC) from 1985 to 1990 that varied in terms of the amount and degree of risk reduction strategies employed. An intensively managed (IPM, BMP, and RP) agricultural treatment site (TRT) was studied for pesticide runoff impacts. From 1985 to 1987, there were minimal (some IPM and BMP) management activities at TRT, but from 1988 to 1990, TRT was managed using an intensive risk reduction strategy. A second unmanaged agricultural growing area, Kiawah (KWA), was also studied and compared with TRT in terms of pesticide runoff and the resulting impacts on grass shrimp (Palaemonetes pugio) and mummichogs (Fundulus heteroclitus). A third, non-agricultural, reference site (CTL) was used for comparing results from the managed and unmanaged agricultural sites. In situ toxicity tests and field samples of the grass shrimp populations were conducted at each site and compared in terms of survival and the effectiveness of current risk reduction strategies. Significant runoff of insecticides (azinphosmethyl, endosulfan, and fenvalerate) along with several fish kills were observed at TRT prior to the implementation of rigorous risk reduction methods. A significant reduction of in stream pesticide concentrations (up to 90%) was observed at TRT following the implementation of strict NPS runoff controls, which greatly reduced impacts on estuarine fish and shellfish. At the unmanaged KWA, continued impacts due to the runoff of these insecticides were observed, along with several fish kills, Additional monitoring indicated that gravid female grass shrimp populations from KWA had elevated levels of P-glycoprotein (P-gp), a multidrug resistance protein, which may transport various pesticides across cellular membranes. Comparison of field results with laboratory toxicity tests established that pesticide exposure was the primary cause of observed field impacts at each site. These findings clearly indicate the value of an integrated risk reduction strategy (BMP, IPM, and RP) for minimizing impacts from NPS agricultural pesticide runoff.