RP104 (TUR-1117-827583-1) Identification of metabolites from alkyl-anthracene compounds in rainbow trout (Oncorhynchus mykiss).
Start time: 8:00 AM
Turcotte, D¹, Abudulai, N¹, Witherly, K, Hodson, P¹, Brown, R¹, ¹ School of Environmental Studies, Queen's University, Kingston, Ontario, Canada
Fish are often exposed to polycyclic aromatic hydrocarbons and the toxicity and metabolism of those toxicants is still not completely understood. The excretion mechanism of xenobiotics is composed of a two-step metabolic process. The first step (phase I), which renders compounds more polar, involves cytochrome P450 (CYP) enzymes. The second step (phase II) involves the conjugation of phase I intermediates with glucuronic acid, glutathione, sulfate or amino acid moieties. CYP enzymes, although part of a mechanism of detoxification, often enhance the general toxicity of anthracene (ANT) derivatives by forming reactive oxygen species. The purpose of this study was to investigate the metabolism of ANT and alkyl-ANTs by rainbow trout (Oncorhynchus mykiss). Phase I metabolites were investigated in vitro by incubating single ANT and alkyl-ANTs with postmitochondrial supernatant fraction (S9 fraction). Phase II metabolites were investigated in vivo by exposing rainbow trout to the same compounds through intraperitoneal injection for a period of 24 hours, after which the gall bladder was sampled. Phase I and biliary phase II metabolites were identified using HPLC coupled with a UV-diode array absorbance detector. Alkyl-chain and ring hydroxylated compounds were found as phase I intermediates. Alkyl-chain and ring glucuronide conjugates were also found for all alkyl-ANTs investigated. Ring conjugates only were found for ANT, as expected. Further metabolized glucuronide conjugates were also detected which are suspected to be diglucuronide conjugates.

RP105 (GRO-1117-840406) Effects of metals on embryonic development in Xenopus tropicalis.
Start time: 8:00 AM
Gross, J¹, Chen, T¹, Karasov, W¹, ¹ Universtiy of Wisconsin--Madison, Madison, Wisconsin, US
Few toxicity studies have been directed at the only diploid Xenopus species, Xenopus (Silurana) tropicalis. While there have been studies characterizing acute responses in Xenopus laevis adults and embryos to heavy metals the responses of X. tropicalis is unknown. We conducted embryo toxicity assays exposing Neiwenkoop and Faber Stage 8 embryos in FETAX solution to cadmium, chromium, copper, lead, mercury, selenium, and zinc. Equal numbers of embryos were selected from a minimum of four proven breeders and randomly distributed among six well cell culture plates (n=24 individuals a treatment). Embryos, with jellycoat intact, were monitored daily for 72 hours and mortality, developmental stages, and malformations were recorded. This is the first study to assess the lethality of heavy metals on X. tropicalis embryonic development. [Supported by Sea Grant R/MW-84, EPASTAR Predoctoral Fellowship]

RP106 (TED-1117-835334) Responses of Microcystis sp. to exposures of a copper-based algaecide.
Start time: 8:00 AM
Tedrow, O.¹, Duke, B.¹, Rodgers, Jr., J.¹, ¹ Clemson University
Microcystis is a cyanobacteria genus that may produce secondary compounds affecting taste and odor of infested water bodies. Microcystis may also produce the potent algal toxin, microcystin. A widely used approach to control the growth of this problematic algal genus has been treatment of infested waters using copper sulfate or chelated-copper containing algaecides. Some modes of action of copper-containing algaecides would target photosynthetic and/or respiratory processes and could result in cell death without leakage of secondary compounds. Microcystis sp. from Pawnee Lake in Nebraska produces ambient water concentrations of microcystin above 10 ppb and was used for this research. Two objectives for this research were 1) to measure responses of Microcystis sp. from Pawnee Lake in NE to exposures of copper-containing algaecide (Cutrine®-Ultra) in the laboratory (with specific interest in the LC₁₀₀); and 2) to determine the influence of algaecide exposures on ambient water concentrations of microcystin in site water post exposure to Cutrine®-Ultra. With an exposure of 0.6 ppm as Cutrine®-Ultra for 96 hours, no measurable Microcystis sp. cells remained in the water column. A 0.05% w/v mixture of Toluidine Blue-O stain was used to distinguish affected Microcystis sp. cells from unaffected control Microcystis sp. cells. In the exposure concentration of 0.6 ppm as Cutrine®-Ultra, greater than 50% of settled Microcystis sp. cells were stained. No statistically significant increase in ambient water concentration of microcystin was observed due to exposures to concentrations of copper as Cutrine®-Ultra (alpha = 0.05). The microcystin concentration measured from the 0.6 ppm exposure in this experiment (0.730 ppb) is below the WHOs recommended tolerable daily intake (TDI) of 1.0 ppb. In this experiment, specific concentrations of a chelated-copper containing algaecide can control Microcystis sp. with no statistically significant increase of microcystin in the ambient water column.

RP107 (GRO-1117-839318) Effects of heavy metals on survival of Ribeiroia ondatre cercariae.
Start time: 8:00 AM
Gross, J¹, Johnson, P¹, Schowalter-Hay, E¹, Chen, T¹, Karasov, W¹, ¹ University of Wisconsin - Madison, Madison, Wisconsin, US
Concerns over global amphibian population declines and amphibian malformations have prompted research into the effects of both pathogens and environmental contaminants. Pollutants such as polychlorinated biphenyls and heavy metals have been shown to alter immune function in vertebrates contributing to the many possible hypotheses of population declines. Amphibians are undoubtedly exposed to heavy metals pollutants which may increase their susceptibility to disease agents. The trematode parasite Ribeiroia ondatrae has been shown to be lethal and induce developmental malformations in a number of amphibian species, including the northern leopard frog, Rana pipiens. Yet the relationship between heavy metals and R. ondatrae survival has never been investigated. This study examines the effects of five heavy metals commonly present in freshwater systems (aluminum, arsenic, chromium, copper, and lead) on the survival of R. ondatrae cercariae shed from wild-caught snail (Planorbella trivolvis) hosts. Aluminum, copper, and lead significantly reduced survivorship of cercariae at ecologically relevant concentrations (P<0.05). However, parasites survived long enough in all concentrations to conceivably find and infect potential amphibian hosts. This is the first study that examines the effects of heavy metals on Ribeiroia ondatrae cercariae

RP108 (GRO-1117-839259) Effects of cadmium on Ribeiroia ondatrae miracidia development.
Start time: 8:00 AM
Gross, J¹, Johnson, P¹, Prahl, L¹, Chen, T¹, Karasov, W¹, ¹ Universtiy of Wisconsin--Madison, Madison, Wisconsin, US
Disease agents and environmental pollutants have been implicated in global amphibian declines and in an increased prevalence in amphibian developmental malformations. Infestation by the trematode parasite, Ribeiroia ondatrae, has been shown to cause embryo mortality and developmental malformations, (i.e. hind limb malformations), in many amphibian species. Additional impacts such as heavy metal pollution in aquatic ecosystems may also factor in amphibian development and health. Few studies, however, have looked at the effects of heavy metals on parasite development. This study examines the effect of cadmium on R. ondatrae miracidia (the first free swimming life stage of the parasite). Fourteen day old adult trematodes were isolated from day old exposed single comb white leghorn chickens, Gallus domesticus. Ova, once removed, were randomly assigned to five treatment groups and survival and development was monitored until miracidia hatching. This study will further elucidate the role of heavy metal contamination on global amphibian declines and malformations by examining a free swimming stage of an amphibian parasite. This is the first study that examines the effects of a heavy metal on R.ondatrae miracidia.

RP109 (MAN-1117-848129) Bioenergetic effects of aqueous cadmium and copper on Palaemonetes pugio.
Start time: 8:00 AM
Manyin, T¹, Rowe, C¹, ¹ Chesapeake Biological Lab, University of MD Center for Environmental Science, Solomons, MD, USA
Palaemonetes pugio (grass shrimp) adults were exposed to either aqueous cadmium or copper for 14 days in a laboratory experiment to determine effects on survival and bioenergetic parameters. The threshold for lethal effects occurred at free ion concentrations of 0.004 mg Cd²⁺/L and 0.06 mg Cu²⁺/L. A dose-dependent increase in metabolic rate, measured by rate of oxygen consumption, was observed for cadmium concentrations ranging from 0.002 to 0.006 mg Cd²⁺/L. These cadmium concentrations resulted in a decrease in growth rate. These data, in combination with reduced fecundity observed in P. pugio exposed to 0.002 mg Cd²⁺/L for a full life cycle, suggest that cadmium exposure causes an energy shift from production to metabolic pathways. Conversely, a dose-dependent decrease in metabolic rate was observed in P. pugio exposed to copper concentrations ranging from 0.01 to 0.06 mg Cu²⁺/L. The inability of P. pugio to produce viable eggs at these copper concentrations prevents measurement of the energy devoted to reproductive pathways. Effects of cadmium and copper exposure on energy storage, in the form of lipids, will also be presented. Results suggest that the bioenergetic responses of P. pugio to cadmium and copper differ greatly.

RP110 (GRO-1117-840572) Effects of methylmercury on development in northern leopard frogs.
Start time: 8:00 AM
Gross, J¹, Chen, T¹, Karasov, W¹, ¹ University of Wisconsin - Madison, Madison, Wisconsin, US
While there have been many studies characterizing acute responses in amphibian adults, embryos and larvae to heavy metals such as methlymercury the responses of amphibians to chronic exposure to this metals is generally unstudied. Some metals are putative endocrine disruptors and affect sexual development, reproduction, and metamorphosis but the sensitivity of amphibians to these effects are also unstudied. We orally exposed tadpoles of northern leopard frogs (control, 10.0, 100.0, 500.0, 1000.0, and 5000.0 ng/g methylmercury fresh weight, as methylHgCl; static renewal system) to doses of methylmercury from Gosner stage (GS) 25 to GS 46, complete tail resorption. Tadpole mortality, growth (snout vent length), and GS was positively correlated with dose and was significantly higher in the 5000.0 ng/g treatments than all other treatments by week two (P<0.05). Tadpole survival was >82% through GS 42, forelimb emergence, for all other treatments. Sublethal effects of methylHg on growth, development, and metamorphosis were not affected at lower concentrations for all other treatments when compared with controls. Sublethal impacts of methylHg on reproductive and neurological tissues and on behavior (i.e. swimming speed) were analyzed and results will be reported. This is the first chronic sublethal methylHg study for northern leopard frogs. [Supported by Sea Grant R/MW-84, EPASTAR Predoctoral Fellowship]

RP111 (MAR-1117-815666) Evaluation of copper water quality standards and criteria for freshwater mussels.
Start time: 8:00 AM
March, F¹, Dwyer, F², Ingersoll, C³, Wang, N⁴, Augspurger, T⁵, ¹ Oklahoma Department of Wildlife Conservation, Oklahoma City, OK, USA² U.S. Fish and Wildlife Service, Columbia, MO, USA³ Columbia Environmental Research Center, USGS, Columbia, MO, USA⁴ Columbia Environmental Research Center, USGS, Columbia, MO, USA⁵ U.S. Fish and Wildlife Service, Raleigh, NC, USA
The Oklahoma Department of Wildlife Conservation has designated several areas as mussel sanctuaries in an attempt to provide mussel species a degree of protection and to facilitate their reproduction. These areas support a diversity of mussel fauna including commercially valuable and non-commercial species. We evaluated the protection afforded freshwater mussels by Oklahoma copper water quality standards (WQS; OWRB, 2001) and U.S. Environmental Protection Agency copper water quality criteria (WQC; USEPA, 1995). Both the CMC (criterion maximum concentration) and CCC (criterion continuous concentration) were considered for the WQS and WQC. Published copper toxicity data were obtained for exposures conducted with glochidia and juvenile mussels. In addition, unpublished mussel toxicity data for copper from the U.S. Geological Survey was also utilized. We evaluated the appropriateness of glochidia and juvenile data including length of exposure, lifestage exposed, and data quality. Copper effect concentrations were corrected to a consistent water hardness. The number of acute toxicity tests for each species ranged from one (5 different species) to as many as 22 tests (1 species). We tabulated toxicity data for glochidia, juveniles or glochidia and juveniles to calculate Species Mean Acute Values (SMAVs) for 20 species and 14 genera. Generally, freshwater mussels had SMAVs for glochidia and juveniles that were similar to the SMAVs of the more sensitive species included in the USEPA water quality derivation database. The majority of the data tabulated was acute lethality data. There were limited chronic exposures or sublethal data available and acute to chronic ratios were utilized to calculate the CCC. The overall protection of freshwater mussel populations provided by copper WQS and WQC will be discussed.

RP112 (SNY-1117-803500) Metal contamination and invertebrate communities in a freshwater ecosystem in the Western Cape, South Africa.
Start time: 8:00 AM
Mothae, L¹, Snyman, R¹, Odendaal, J¹, ¹ Cape Peninsula University of Technology, Cape Town, Western Cape, South Africa
Freshwater ecosystems in South Africa are threatened by heavy metal pollution. Most riverine ecosystems in the Western Cape are regularly monitored for bacterial and some chemical pollution. However, heavy metal pollution monitoring is neglected and where it is done, few attempts are made to investigate the actual toxicity of such metals to the freshwater biota. The Diep River is one of the major freshwater ecosystems in the Western Cape. It includes a sensitive wetland area that receives runoff directly from a large industrial area and a densely populated urban area. The aim of this study is to monitor the levels of heavy metal pollution in the Diep River, as well as to investigate the toxicity of these metals to the river biota. One such aspect that is currently being investigated and will be outlined in the poster, is the possible contribution of metal pollution to invertebrate community effects, using SASS (South African Scoring System for invertebrates). The SASS score provides an indication of general river health, with an average score per invertebrate taxon of < 5 indicating increasingly compromised river health. Three river sites are being monitored, one before, one within and one after the wetland area. Preliminary results indicate that metals such as chromium, cadmium, copper, aluminium, lead and zinc are particularly high in sediments at the wetland site, due to the fact that most of the industries are concentrated here. Metal concentrations at the downstream site are generally significantly lower, possibly due to a filtering effect of the wetland. SASS scores for the wetland site are consistently below 3, whereas scores for the downstream site are above 4. At this stage it seems that higher metal concentrations in the Diep River are associated with lower SASS scores, indicating a possible relationship between metal contamination and invertebrate community structure.

RP113 (WIG-1117-576287) Effects of cadmium and body mass on the anti-predator behaviors of five species of crayfish.
Start time: 8:00 AM
Wigginton, A¹, Cooper, R¹, Birge, W¹, ¹ University of Kentucky, Lexington, KY, USA
Five crayfish species (Orconectes placidus, O. virilis, Procambarus acutus, P. alleni, and P. clarkii) were subjected to cadmium exposure in 96h acute tests. The tail-flip predator avoidance behavior was significantly affected by cadmium exposure in each case (ANOVA p<0.05). Four species showed at least one exposure concentration that was reduced significant compared to controls (Tukey-HSD p<0.05). In three of the five species, the claw raise defensive behavior also was significantly affected by cadmium exposure (ANOVA p<0.05). In each of these three cases, at least one exposure concentration of cadmium reduced the claw-raise behavior significantly compared to controls (Tukey-HSD p<0.05). When control groups were compared across species, a significant correlation was measured between body mass and both the tail flip and claw raise behaviors. Between species, as body mass increased, the tail flip response decreased in frequency (r = -0.87; p<0.0001) , and the claw raise response increased in frequency (r= 0.68; p<0.0001). P. clarkii was also analyzed for the effect of Cd exposure on heart rate and response to two stimuli. Some alteration was observed in the circadian rhythm of crayfish under Cd exposure. Heart rate decreased by 56% (p<0.01) relative to pretreatment levels as crayfish succumbed to cadmium toxicity. In each control individual, heart rate slowed after a mild stimulus of 3 glass beads being dropped into the exposure chamber. After a stronger stimulus, a tap on the abdomen with a glass rod, heart rate increased in control animals. No heart rate trends were evident in Cd exposed crayfish. These data indicate that heart rate measurements may be useful as a physiological marker of cadmium toxicity.

RP114 (GRI-1117-828661) Decreased survival of trematode cercariae (Echinostoma trivolvis ) following atrazine and metolachlor exposure.
Start time: 8:00 AM
Griggs, J¹, Belden, L¹, ¹ Virginia Polytechnic Institute and State University, Blacksburg, VA, United States
Atrazine and metolachlor are two widely used agricultural herbicides that inhibit the growth of pre-emergent vegetation. Residues of these pesticides are commonly found in bodies of water near agricultural areas. While extensive studies have been conducted on individual pesticides and their effects on single species, less is known about the effects that pesticides can have in more complex biological systems, such as host- parasite systems. We are examining pesticide impacts in aquatic disease systems involving digenean trematodes with complex life cycles (a definitive host and two intermediate hosts). In this study, we investigated the effects of environmentally realistic concentrations of atrazine and metolachlor on the survival of trematode ( Echinostoma trivolvis ) cercariae. Cercariae are a free-swimming trematode stage that emerges from the first intermediate host and infects the second intermediate host. Cercarial survivorship was monitored every two hours for 21 hours after exposure to low dose (3 ppb and 15 ppb) and high dose (100 ppb) concentrations of metolachlor and atrazine individually and as mixtures (10 ppb: 15 ppb, 85 ppb: 100, respectively). Control cercariae survived significantly longer than any of the pesticide exposed cercariae. Within the pesticide exposed groups, cercariae exposed to metolachlor survived significantly longer than those exposed to any dose of atrazine or to the pesticide mixtures. The results suggest that E. trivolvis cercariae are sensitive to both pesticides, although perhaps more so to atrazine. These changes in parasite survivorship can potentially affect trematode disease dynamics in polluted systems by altering parasite loads in hosts, rates of disease transmission, and natural population regulation and stability.

RP115 (BRA-1117-827343) Comparative toxicity of agricultural pesticides in three strains of the fairy shrimp Thamnocephalus platyurus.
Start time: 8:00 AM
Brausch, John¹, Smith, Philip¹, ¹ The Institute of Environmental and Human Health, Texas Tech University, Lubbock, Texas, USA
The Southern High Plains (SHP) is a 31,700 sq. mile region that starts at the Canadian River in west Texas and extends south past Lubbock, TX and westward into eastern New Mexico. The most important ecological features in the SHP are small temporary water bodies known as playas. Intensive farming in this region has introduced several new stressors into playa wetland ecosystems including increased sediment deposition, shortened hydroperiods, and agricultural chemicals through runoff and spray drift. Playas are home to many important invertebrate species including fairy shrimp which provide food for amphibians, mammals, and waterfowl. Thamnocephalus platyurus is a fairy shrimp native to the SHP playas, but is also available commercially and is commonly used in aquatic toxicity testing. Acute toxicity of four commonly used agricultural pesticides (Tempo [active ingredient cyfluthrin], methyl parathion, Roundup [glyphosate] and Karmex [diuron]) was measured in three different strains of T. platyurus: commercially available laboratory cultured shrimp, shrimp from native grassland playas, and shrimp from agriculturally impacted playas. Laboratory cultured shrimp experienced toxicity (48 hour LC50) at 1.19 g/L for Tempo and 801.61 g/L for Roundup. These values are compared to those of shrimp from native grassland playas as well as shrimp from playas surrounded by agricultural areas.

RP116 (RAL-1117-844847) Species sensitivity distribution of aquatic biota exposed to soybean rust fungicides.
Start time: 8:00 AM
Ralston-Hooper, K¹, Ochoa-Acuna, H^{2, 3}, Hahn, L⁴, Shaner, G⁵, Sepulveda, M^{1, 3}, ¹ Department of Forestry and Natural Resources, Purdue University² Department of Veterinary Pathobiology, Purdue University³ Department of Civil Engineering, Purdue University⁴ Office of Indiana State Chemist⁵ Department of Botany and Plant Pathology, Purdue University
Asian soybean rust Phakopsora pachyrhizi is a highly contagious, fungal crop disease recently detected in several US states. The introduction of this pest has prompted the EPA to approve emergency exceptions for several fungicides that have not yet been registered for use in the US. To date, 14 active ingredients (azoxystrobin, chlorothalonil, cyproconazole, famoxadone, flusilazole, flutriafol, metconazole, myclobutanil, propiconazole, prothioconazole, pyraclostrobin, tebuconazole, tetraconazole, and trifloxystrobin) have been approved for use against soybean rust, of which only three (chlorothalonil, azoxystrobin, and pyraclostrobin) have been granted full registration. Given that the vast majority of fungicides under evaluation lack data on chronic exposure for invertebrates and alga, two toxicity tests were conducted for all active ingredients: the chronic 7-day Ceriodaphnia dubia survival and reproduction test and the chronic 4-day green alga Selenastrum capricornutum growth test. Toxicity tests were also performed using Diporeia spp. and Hyallela azteca. Risks were evaluated through the development of species sensitivity distributions of lowest effects (LOEC), no observable effects (NOEC), and median effects (EC50) concentrations using published data, values extrapolated using computational toxicology approaches, and results of these toxicity tests. Aquatic organisms encompass a wide range of physiological and life history characteristics, and therefore their sensitivity to a particular chemical can vary considerably. Species sensitivity distributions provide a statistical mechanism for describing such interspecific variation.

RP117 (PAC-1117-823732) Metal toxicity to Ceriodaphnia dubia as a probe of the kinetic lability of metal complexes.
Start time: 8:00 PM
Pac, C¹, Jones, A¹, Carraway, E^{1, 2}, ¹ Clemson Institute of Environmental Toxicology, Pendleton, South Carolina, United States² Clemson University Department of Environmental Engineering and Science, Anderson, South Carolina, United States
It is well documented that complexation of metals to certain types of ligands decreases the bioavailability of the metal, thus reducing its toxicity. Analyses using equilibrium descriptions of metal complexation have generally been successful in relating toxicity to metal speciation, but important questions remain. The current work is a continuation of previous research on mercury (Hg) complexation by natural organic matter (NOM) which showed that increases in NOM concentrations are not always accompanied by decreases in Hg toxicity. It was hypothesized that this may be indicative of the kinetic lability of the Hg-NOM complex. Due to the lack of comprehensive data on the kinetic lability of metal complexes, additional toxicity studies were completed under selected conditions in order to gain a better understanding of importance of speciation dynamics in aquatic environments. This hypothesis was tested using a series of complexation experiments where Visual MINTEQ was used to determine the equilibrium speciation of copper, mercury, and aluminum in the presence of simple, well-studied ligands. Toxicity tests using Ceriodaphnia dubia and various metal-ligand combinations were then performed to determine if equilibrium speciation modeling and toxicity were well correlated. When possible, results were also compared to predictions made by the Biotic Ligand Model (BLM). Following these studies, Hg complexation to NOM was assessed in a similar manner. Aquatic NOM was separated into selected size fractions. Each fraction was then complexed with Hg and the toxicity of the Hg-NOM mixture to Ceriodaphnia dubia measured. Preliminary results indicate toxicity tests can be an indicator of the kinetic lability of metal complexes when performed under conditions of low free metal concentrations. Interactions and predictions become more complex when metals are bound to NOM due to the large number of functional group types and numbers present.

RP118 (JAR-1117-826307) Impacts of brief malathion exposure on olfactory, brain, and liver acetylcholinesterase activity in striped bass.
Start time: 8:00 AM
Jarrard, H¹, Metcalf, B¹, ¹ Department of Biology, Washington College, Chestertown, Maryland, USA
Numerous organophosphate (OP) pesticides inhibit acetylcholinesterase (AChE) activity in teleost brain (BR) and liver (L), and are correlated with increased mortality and behavioral alteration over standard testing durations of 24-96 hours. AChE activity in the teleost olfactory system (olfactory rosette, OR, and olfactory bulb, OB) can also be inhibited by these pesticides, even with brief exposures. This inhibition may be correlated with neurophysiological and behavioral impairment affecting behaviors reliant on a functional sense of smell (such as predator avoidance). In this preliminary range-finding study, we investigated the effects of brief exposure (4 hours) to the OP pesticide malathion on BR, L, OR, and OB AChE in the striped bass (Morone saxitilis). Furthermore, because this teleost inhabits coastal bays/estuaries often experiencing hypoxic conditions in summer months due to eutriophication, malathion exposure (0.25X, 0.5X, and 1X the 96hr LC50) occurred in either normoxic (5.8-7.3 mg/L O2) or hypoxic (1.35-3.5 mg/L O2) conditions. Seven exposure groups were pulse-exposed in flow-through tanks: Control (0 g/L malathion, normoxic), Low, Medium, and High-dose Normoxic (60, 120, and 240 g/L malathion), and Low, Medium, and High-dose Hypoxic (same malathion doses). Flash-frozen tissues were then collected and AChE activity measured. In results, all doses examined significantly reduced AChE activity relative to controls (one-way ANOVA, Dunnetts post hoc, 0.05 level): BR AChE activity was reduced to 10-42 % of control values, while L, OR and OB AChE activity was reduced to 4.9-9.4 %, 34.5-63.3 %, and 15.6-40 % of control values, respectively. No significant differences were observed between normoxic and hypoxic conditions at different doses, although effects may have been masked by the substantial AChE inhibition caused by the initial doses used. In summary, these results show that brief exposures to malathion profoundly impact olfactory, brain, and liver acetylcholinesterase activity, and potentially, dependant behaviors.

RP119 (CAR-1117-830971) Amphibian risk assessment and glyphosate herbicides: Key considerations for laboratory and field studies.
Start time: 8:00 AM
Carr, K¹, Levine, S¹, Farmer, D¹, Honegger, J¹, ¹ Monsanto Company, Saint Louis, MO, USA
In recent years, a number of published studies have examined the potential for adverse effects of glyphosate herbicide formulations on amphibian growth, development, behavior and survival. These studies have included laboratory, simulated field, and field exposure studies to a variety of amphibian species. Due to the lack of established test guidelines for amphibian studies, the study protocols vary considerably among researchers, which can make comparison of results among multiple studies difficult. Herbicide formulations and exposure concentrations studied vary significantly, and some exposure concentrations are much higher than the levels that have been shown to be present in the environment following herbicide application. Moreover, processes of dissipation from the water column, biodegradation, and bioavailability are often not addressed in the study design. Therefore, the results from studies in which test animals are continuously exposed in artificial systems at unrealistically high concentrations must be evaluated with caution. This presentation examines several recently published studies that have evaluated the potential for effects of glyphosate herbicide formulations to amphibians. This analysis compares the exposure regimes used in these studies with environmentally realistic exposure scenarios, in order to put the results of these studies into the proper context for evaluating ecological risk.

RP120 (GRU-1117-930240) Do juvenile salmon avoid commonly used aquatic herbicides?
Start time: 8:00 AM
Curran, Catherine¹, Grassley, James¹, grue, christian¹, ¹ University of Washington, seattle, WA, USA
Herbicides are frequently used to control exotic or nuisance aquatic plants. However, the use of herbicides to control aquatic weeds has been hampered by concerns directed at the non-target toxicity of active herbicidal ingredients, particularly in light of new State permitting processes in response to a recent Federal Court ruling, requiring states to issue National Pollutant Discharge Elimination System permits for the use of pesticides and adjuvants in aquatic systems. Unfortunately, adequate data on the non-target toxicity of aquatic herbicides are lacking, thereby threatening the permitting process. Recent declines in several species/stocks of salmon and the emphasis to restore these populations heighten concerns in the Pacific Northwest. Behavioral responses such as avoidance can alter the exposure of fish to pesticides and such behavior has been suggested as important in mitigating the hazards aquatic herbicides pose to juvenile salmonids provided suitable uncontaminated habitat is accessible. The aquatic herbicides we selected to study, Sonar® AS (fluridone), REWARD® (diquat), and RENOVATE® 3 (triclopyr), are permitted for use in Washington State. Our objective was to determine if juvenile Chinook salmon (Oncorhynchus tshawytscha) avoid these herbicides. The maximum application rate and ten times the maximum application rate were tested as well as positive controls. We used five replicate uni-directional flow chambers adapted for juvenile Chinook and photographed the position of fish (n=10/chamber) for 15 min (1-min intervals) before chemical exposure, during chemical exposure, and after clean water was re-introduced into the chambers. One water sample from each concentration tested was chemically analyzed. Responses were quantified using a novel method comparing mean position and slopes of lines generated by mean position in the test chambers over time. Juvenile chinook were neither attracted to or avoided the maximum label rates of the herbicides, but were attracted to 10x the maximum label rates of RENOVATE and REWARD.

RP121 (KOO-1117-771547) Effects of 2,4-D on wood frog (Rana sylvatica) tadpoles.
Start time: 8:00 AM
Koop, M J¹, Forsyth, D J ², ¹ Toxicology Centre, University of Saskatchewan, Saskatoon, Saskatchewan, Canada² Canadian Wildlife Service, Saskatoon, Saskatchewan, Canada
Amphibians are undergoing global population decline, as well as an increase in the occurrence of deformities. Herbicides, particularly 2,4-D, are applied annually to most cropland in Saskatchewan. An endocrine disruptor, 2,4-D enters wetlands in combination with other herbicides in runoff and by aerial transport, and therefore represents a potential threat to normal development. The purpose of this study was to investigate the sublethal effects of prairie herbicides, primarily 2,4-D, on growth and development of Wood Frog (Rana sylvatica) tadpoles, a native Saskatchewan species, from hatching to metamorphosis. Metamorphs were sampled from 10 agricultural ponds (five treated with 2,4-D at 10 g.L-1) and 10 nonagricultural ponds. Water samples were analyzed for herbicide residues, pH, conductivity, nitrates + nitrites and ammonia before and after herbicide application by local farmers and again when metamorphs were collected. The metamorphs were examined for body condition, gonadal development and occurrence of deformities, and were subjected to a standardized stress protocol. Blood samples were collected via heart puncture and analyzed for corticosterone concentrations. These five parameters will be compared between the agricultural and nonagricultural populations.

RP122 (CON-1117-811833) Effects of fungicides on aquatic microorganisms and leaf litter breakdown.
Start time: 8:00 AM
Conners, D¹, Rosemond, A¹, Black, M¹, ¹ The University of Georgia, Athens, Georgia, USA
Aquatic microorganisms play an important role in conditioning leaf litter that enters streams and serves as an important base of production for consumers. Contamination of streams by fungicides may adversely affect microorganisms and alter leaf litter processing rates. Unfortunately, microorganisms are rarely used in acute toxicity tests for fungicide evaluation and registration. We adapted the resazurin reduction assay, which is used in medical microbiology, to assess the acute toxicity of four fungicides (azoxystrobin, trifloxystrobin, kresoxim-methyl and chlorothalonil) to aquatic fungi (Articulospora tetracladia) and bacteria (Cytophaga spp.), and investigated the ability of the toxicants to inhibit leaf breakdown in microcosms. Fungi were more sensitive to fungicides than many standard test organisms (cladocerans, green algae, trout), while bacteria were often the least sensitive. All of the fungicides except kresoxim-methyl, when added to microcosms at concentrations that inhibited the fungi by 90 percent in acute tests, reduced leaf breakdown rates by an average of 14.7 percent. Thus, aquatic fungi and their associated functions in streams may be relatively sensitive to fungicides applied terrestrially that enter streams through non-point sources. These data highlight the importance of including aquatic fungi in safety assessments of pesticides for protection of microbial function.

RP123 (MAG-1117-852015) Evaluation of ecological and hydrological conditions in the Santa Clara River Estuary with respect to discharge of treated effluent.
Start time: 8:00 AM
Magier, S¹, Bailey, H¹, Kamman, G², Pfeifer, D³, ¹ Nautilus Environmental, San Diego, California, United States² Kamman Hydrology and Engineering, Inc., San Rafael, California, United States³ City of San Buenaventura, Ventura, California, United States
The purpose of this study was to evaluate positive and negative impacts associated with discharge of treated wastewater to the Santa Clara River estuary, and identify areas in which the discharge may enhance beneficial uses. Key components of this study included evaluation of changes in habitat type and community assemblages over time, as well as changes in hydrological function. The estuary supports a number of species of regulatory interest, including the federally listed tidewater goby (Eucyclogobius newberryi). Moreover, it is located in a semi-arid region of California that has been subjected to intensive habitat and water development over time, making it problematic to establish baseline conditions. The ecological investigation relied on extensive historical information including USGS maps, aerial photographs, and anecdotal accounts from a variety of sources. Analysis of aerial photographs demonstrated that there were minimal changes in the relative composition of habitat types between 1929 and 2002. Most changes in flora and fauna could be attributed to development of the floodplain that has resulted in a decrease in estuary size of approximately 90%. The hydrological analysis used historical data, anecdotal evidence, and modeling to develop estimates for monthly flows under natural conditions. This analysis showed that the discharge accounts for a portion of the river flows that would historically have reached the estuary, but which have been diverted for other uses upstream. Overall, the analysis indicated that the discharge supports beneficial uses of the estuary, particularly by maintaining water quality and habitat.

RP124 (CRA-1117-852069) A site-specific ammonia limit for effluents.
Start time: 8:00 AM
Craig, Gordon¹, Middelraad, Irene², ¹ G.R Craig & Associates, Schomberg, Ontario, Canada² D.George Dixon & Associates, Guelph, Ontario, Canada
An ammonia effluent limit was developed from continuous flow acute rainbow trout lethality data that could be used by municipal waste treatment operators. Site specificity was based on the change of ammonia potency under different pH conditions and a limit value expressed as total ammonia nitrogen is presented for a range of temperatures. The limit value is based on the 5th percentile of the distribution of rainbow trout LC50 concentrations and is compared to other salmonid species sensitivities to demonstrate its conservative nature in receiving environment conditions. Effluents meeting this limit have a high probability of complying with regulatory compliance requirements.

RP125 (NIE-1117-812755) Effect of sub-lethal concentration of the herbicides hexazinone and atrazine on Atlantic salmon.
Start time: 8:00 AM
Nieves-Puigdoller, K², McCormick, S², ² USGS, Turners Fall, MA, USA
Hexazinone and atrazine are highly mobile herbicides that are widely used along rivers in the United States. Both compounds can be potentially harmful to Atlantic salmon (Salmo salar), which have been recently listed as an endangered species. The objective of this study was to determine the effect of sub-lethal concentrations of the herbicides hexazinone and atrazine on Atlantic salmon. Larvae were exposed to either 100 ppb hexazinone, 10 ppb or 100 ppb atrazine for 21 days at 10 ^oC. Weight, sodium, calcium and whole larvae water content were determined for ten larvae per treatment. The remaining fish were reared for a year and as smolts were analyzed for plasma chloride, calcium, magnesium, cortisol and salinity tolerance. Additionally, smolts were exposed for a second time to 100 ppb atrazine for 13 days. There was no effect of contaminant exposure on larval survival, sodium or calcium concentration. Exposure to 100 ppb hexazinone, 10 and 100 ppb atrazine caused an increase in the rate of opercular movements and whole larvae water content. Exposed larvae exhibited a slight decrease in weight, with only 100 ppb atrazine causing a significant weight loss. Smolt salinity tolerance was not affected by herbicides exposure. Furthermore, no significant change in plasma cortisol, sodium and calcium levels were observed. Smolts previously exposed to sub-lethal concentrations of herbicides as larvae or additional exposed to herbicides for 13 days, show no effect in their osmoregulatory ability and salinity tolerance. We conclude that under the conditions imposed in this study, larval osmoregulatory ability was not affected by these herbicides. Hexazinone does appear to affect some features of larval respiration and atrazine has a substantial impact on larval metabolism.

RP127 (RIN-1117-832593) Cellular responses of oysters to algal toxins.
Start time: 8:00 AM
Ringwood, A¹, Keppler, C², Hoguet, J³, Lewitus, A^{2, 4}, ¹ Deparment of Biology, UNC-Charlotte, Charlotte, NC, USA² SCDNR, Marine Resources Research Institute, Charleston, SC, USA³ Center for Coastal Environmental Health and Biomolecular Research, National Ocean Service, NOAA, Charleston, SC, USA⁴ Belle W. Baruch Institute for Marine and Coastal Sciences, University of South Carolina, Georgetown, SC, USA
While blooms of toxin-producing algae (e.g. harmful algal blooms, HAB) can sometimes cause obvious devastating effects on localized shellfish populations, sublethal impacts of HABs can cause more subtle but very serious problems. Therefore it is important to be able to detect the sublethal impacts of HABs and consider how they may affect population sustainability. We have conducted a variety of field and laboratory studies to evaluate cellular biomarker responses of oysters, Crassostrea virginica , to HABs. One of the most promising biomarkers has been the lysosomal destabilization responses of hepatopancreatic cells. Exposures of oysters to toxic algae collected from the field during active blooms, to laboratory-cultured toxic algae, and to purified algal toxins caused an increase in lysosomal destabilization rates, indicating significant toxicity. Likewise, resident oysters collected from the field during an active bloom also showed increased lysosomal destabilization. Some laboratory studies were also conducted in which oysters were first exposed to toxic algae and then returned to clean seawater. Increased lysosomal destabilization rates were observed during the recovery as well as exposure periods, suggesting that adverse effects on important cellular functions can persist during post-bloom periods. The levels of lysosomal destabilization observed in these studies have also been associated with poor gamete viability and significant effects on reproductive success. There is some evidence that the incidence of HABs has increased, possibly due to increased anthropogenic stress in estuarine and coastal systems. Since HAB events tend to occur during the spring and summer, periods that coincide with the reproductive period of oysters and many other species of shellfish, more sustained long-term impacts of HABs on shellfish populations may be significant.

RP128 (ELP-1117-853890) Characterization of stormwater samples from the Seattle-Tacoma International Airport using toxicity tests and Toxicity Identification Evaluations.
Start time: 8:00 AM
Elphick, J¹, Tobiason, S², Bergmann, K¹, Brix, K³, ¹ Nautilus Environmental, Tacoma, WA, USA² Port of Seattle, Seattle, WA, USA³ EcoTox, Key Biscayne, FL, USA
As part of an ongoing stormwater monitoring program at the Seattle-Tacoma International Airport, acute toxicity tests using Daphnia pulex and fathead minnows were conducted quarterly on stormwater samples collected during storm events from thirteen discharge points. In addition, rainbow trout embryo development tests were conducted semi-annually on ambient water samples from six receiving environment stations. Toxicity was largely restricted to effects on survival of daphnids and limited to samples from three of the thirteen outfalls. Toxicity Identification Evaluation procedures were applied to the majority of samples that exhibited toxicity to daphnids and identified divalent metals (in particular, zinc) as the cause of the observed effects. The role of sample hardness and organic carbon at modulating the toxicity of zinc to D. pulex in samples of stormwater was also characterized. The naturally low hardness of stormwater exacerbated the zinc toxicity. Runoff samples from the three outfalls that drain highly impervious areas (roadways, parking, rooftops) with contained drainage systems had low hardness, elevated metals and were consistently toxic to daphnids. In contrast, runoff samples from the other ten outfalls had higher hardness, lower metals and were consistently non-toxic. Most of these 10 outfalls have drainage systems that provide for generous contact between runoff and grassed areas. These patterns suggest that contained drainage systems can prevent contact between runoff and landscaping that would tend to add hardness and reduce metal concentrations.

RP129 (HUB-1117-850861) Water and sediment quality evaluation of the Santa Clara River Estuary – Analysis of impacts associated with discharge of treated wastewater.
Start time: 8:00 AM
Huber, A¹, Bailey, H², Stransky, C³, ¹ Nautilus Environmental, San Diego, CA, USA² Nautilus Environmental, San Diego, CA, USA³ Nautilus Environmental, San Diego, CA, USA
The City of San Buenaventura currently discharges a monthly average of approximately 7 mgd of tertiary treated effluent into Santa Clara River estuary. The discharge has been ongoing for approximately 45 years. The objective of this study was to evaluate whether chemicals in the effluent may be affecting water and sediment quality within the estuary. Extensive testing with a variety of both marine and freshwater species showed a low incidence and degree of toxicity, and limited exceedences of water quality criteria. The discharge generally did not appear to be associated with toxicity; causes of toxicity appeared to be localized, variable, and related to upstream sources or groundwater influence. The sediment quality evaluation indicated that contaminants of concern were generally below sediment quality guidelines, and most of the responses in the sediment toxicity tests were related to coarse substrate. Copper is a primary constituent of concern for the treatment plant based on frequent exceedence of current marine water quality criteria. However, relationships between copper and toxicity, in addition to a series of water–effect ratio (WER) studies suggest that concentrations of copper in both the WWTP discharge and estuary are below those of potential biological concern.

RP130 (KAN-1117-744769) Harmful algal bloom neurotoxins, brevetoxin and saxitoxin, alter behavior in groups of killifish, Fundulus heteroclitus.
Start time: 8:00 AM
Salierno, J^{1, 2}, Kane, A^{1, 2}, ¹ University of Maryland, Department of Epidemiology & Preventive Medicine, Baltimore, MD, USA² Virginia-Maryland Regional College of Veterinary Medicine, College Park, MD, USA
Harmful algal blooms (HABs), and bloom-associated fish morbidity and mortality, have increased in frequency and severity over the past several decades. The ability to predict and characterize environmental effects of HABs are essential to bloom remediation and control. This behavioral toxicology study investigated the effects of low-level, environmentally-realistic, HAB neurotoxin (40-55 ppb brevetoxin, PbTx-2; and 100-150 ppb saxitoxin, STX) exposures on swimming behaviors in groups of killifish (a.k.a. mummichog), Fundulus heteroclitus. Fish were additionally exposed to a common fish anesthetic, MS-222, for validation and comparison to HAB toxins. Video segments before, during and after exposures were collected and analyzed using a custom behavioral analysis system. In addition, predator avoidance (bird model) and startle responses (auditory/vibratory) were compared before and after toxin exposure. Mummichog exposed to HAB toxins and MS-222 had significant alterations in schooling and shoaling behaviors. Exposure to STX and MS-222 significantly decreased (p ≤ 0.09) fish interactions, and schooling and shoaling frequencies, whereas exposure to PbTx-2 increased (p ≤ 0.08) these behaviors. The number of sedentary groups of fish significantly (p ≤ 0.05) increased in association to exposure to MS-222, and the frequency of solitary behaviors significantly (p ≤ 0.03) increased with all HAB exposures. Compositions of schools, shoals and sedentary groups significantly decreased from groups of 5 to groups of 3 after exposure to all three compounds (p ≤ 0.09). Additionally, exposure to all three toxins altered startle response and predator response behaviors. Twenty-four hours after exposure, groups of fish exposed to all 3 toxins had significant (p ≤ 0.10) decreases in activity and frequency of behaviors compared with pre-exposure activity. These results indicate that sublethal exposure to HAB toxins can have demonstrable, biologically-relevant effects on swimming and social behaviors, as well as on startle and predator avoidance responses.

RP131 (THR-1117-149274) Identification of Selenoproteins in Selenium-Sensitive Tissues in Japanese Medaka (Oryzias latipes) Using Tandemly Coupled HPLC-ICPMS.
Start time: 8:00 AM
Thrippleton, K.¹, Schlenk, D.¹, Mason, A.², ¹ University of California, Riverside, Riverside, CA, US² California State University, Long Beach, Long Beach, CA, US
Selenium (Se) is an essential micronutrient for many organisms, but for oviparous vertebrates, Se at slightly elevated levels becomes highly toxic. Sulfur (S), a fundamental constituent of many proteins, is found in the disulfide bond linkages (S-S linkages) between amino acid strands. The similarities in chemical and physical properties of Se and S have been used to support the hypothesis that Se exerts its toxicity by interfering with disulfide bonds. This can result in distorted, dysfunctional proteins and enzymes, which ultimately could impair normal cellular biochemistry. Studies are currently underway to determine proteins in Japanese Medaka fish (O. latipes) that may be affected by Se toxicity after dietary exposure to the metal. Brine shrimp (Artemia) used for the dietary exposures to O. latipes were exposed to 100 ppm Selenomethionine (SeMet) for 1 hour. Se levels in exposed Artemia averaged 40.19 ± 3.61 g Se/g dry weight. Assimilation of Se into proteins from O. latipes liver, gonad, and egg samples following dietary exposure were evaluated by size-exclusion HPLC tandemly coupled to ICPMS (Perkin Elmer 6100 DRC) for concurrent protein/metal analysis. The identification of these Se-affected proteins could aid in better understanding of Se toxicity within oviparous organisms.

RP132 (WAN-1117-663237) Acute and chronic toxicity of copper, ammonia, and chlorine to early life stages of freshwater mussels.
Start time: 8:00 AM
Wang, N¹, Ingersoll, C¹, Greer, I¹, Whites, D¹, Dwyer, F², Roberts, A², Augspurger, T³, Kane, C⁴, Neves, R⁵, Barnhart, M⁶, ¹ U.S. Geological Survey, Columbia, MO² U.S. Fish and Wildlife Service, Columbia, MO³ U.S. Fish and Wildlife Service, Raleigh, NC⁴ U.S. Fish and Wildlife Service, Gloucester, VA⁵ U.S. Geological Survey, Blacksburg, VA⁶ Southwest Missouri State University, Springfield, MO
Early life stages of freshwater mussels are reportedly more sensitive to many chemicals compared to common test organisms. However, concerns have been expressed regarding the lack of standardization of methods for conducting toxicity test with freshwater mussels. The objectives of this project were to (1) refine methods for conducting toxicity tests with early life stages of freshwater mussels and (2) evaluate acute and chronic toxicity of copper, ammonia, and chlorine to larval (glochidia) and juvenile mussels. During the past four years, over 120 acute and 2 chronic toxicity tests with copper, ammonia, or chlorine were conducted with 15 mussel species and 5 common test organisms. The results of 48-h tests with glochidia, 96-h toxicity tests with newly-released juveniles and 2-month-old juvenile mussels, and 28-d tests with 2-month-old juvenile mussels of all species tested demonstrated that early life stages of mussels were generally more sensitive to copper and ammonia than five common test species of fish, cladocerans, or amphipods. Based on 4-d acute and 28-d chronic tests with juvenile mussels, acute to chronic ratios were calculated as 2.7 for copper and 7.6 for ammonia. The median effect concentrations (EC50s) or chronic values of copper and ammonia for glochidia and juvenile mussels were typically at or below the acute or chronic USEPA water quality criteria (WQC), whereas EC50s of chlorine were generally above the acute WQC. Results indicate that the current acute and chronic WQC for copper and ammonia might not provide adequate protection to mussel species. The methods for conducting toxicity tests with freshwater mussels are currently being balloted through ASTM and toxicity data generated with mussels using these methods should be useful for developing WQC.

RP133 (OZM-1117-786107) Toxicity of Some Textile Dyes on Xenopus laevis Tadpoles.
Start time: 8:00 AM
Birhanli, A¹, Gungordu, A¹, Ozmen, M¹, ¹ Inonu University, Malatya, Turkey
The textile industries consume large volumes of water and chemicals for wet processing of textiles. Some textile dyes and their wastewater were found significantly toxic on aquatic organisms. Therefore, Xenopus laevis tadpoles were exposed to astrazon red FBL, astrazon blue FGRL, remazol red RR, remazol turquoise blue G-A, cibacron red FN-3G and cibacron blue FN-R for a 168-h exposure period in static renewal test conditions in developmental stage 46. Median lethal concentration (LC50) was determined as 8.42 and 1.90 mg/L for astrazon red and blue, 2989 and 747 mg/L for remazol red and blue, and 6406 and 1144 mg/L for cibacron red and blue, respectively, on tadpoles by the 24-h exposure period. The LC50 values were found as 0.35 mg/L, 0.13 mg/L, 111 mg/L, 6.97 mg/L, 359 mg/L and 15.7 mg/L for the tested dyes, respectively, during 168-h of exposure period where tadpole growth was determined to be effected by increased dye concentrations at signinificant levels (p<0.05 or p<0.005). Furthermore, selected enzyme activities glutathion S-transferase (GST), lactate dehydrogenase (LDH) and carboxylesterase (CE) were significantly changed by the 24-h. The results showed that dyes caused a high toxicity on Xenopus laevis tadpoles at stage 46. Of the dyes tested, astrazon group dyes were found to be the most toxic ones with astrozon blue being the more toxic dye of this group.

RP134 (MAS-1117-749671) Characterizing and mitigating risks of oil-contaminated stormwater to aquatic biota.
Start time: 8:00 AM
Mastin, B¹, ¹ WaterSolve, LLC, Grand Rapids, Michigan, USA
Contaminated stormwater runoff is an issue of increasing national concern for public health officials, engineers, urban planners, environmental scientists, and the general public. Crankcase oil is a complex mixture of several potentially toxic elements and compounds including aliphatic and aromatic hydrocarbons, metals, and other organic and inorganic compounds (e.g., Zn, Cd, Mg, surfactants, phenates, phosphates, and sulphonates) that enters surface waters through stormwater runoff with sufficient concentration and duration of exposure to cause adverse effects to aquatic receiving system biota. In general, toxicity of oil-contaminated waters cannot be consistently attributed to any one element or compound, and observed toxicity may be a consequence of additive or synergistic interactions of components or fractions of the mixture. Toxicity Identification Evaluation (TIE) methods involving fractionation of the complex mixture and the differential responses of several test species (i.e., biodirected analysis), can be used to identify toxic fractions and illustrate transfers and transformations necessary to mitigate risks from crankcase oil-contaminated stormwater. Once toxic fractions are identified and verified, toxicity identification approaches and kinetic data can be applied to determine analogous treatment or remediation tactics (e.g., oil/water separation, sorption with inorganic and organic ligands, biodegradation, etc.) that may be combined into a strategy to remove oil and ameliorate toxicity from sources such as stormwater. The objectives of this research were to 1) characterize the relative risks of new crankcase oil in freshwater, 2) identify appropriate risk mitigation strategies through TIE manipulations of simulated oil-contaminated stormwater, and 3) design, construct, and evaluate the function and performance of pilot-scale constructed wetland systems for mitigating these ecological risks arising from simulated oil-contaminated stormwater. Performance kinetics from these systems can subsequently be used to scale-up the pilot-scale treatment systems and potentially construct wetlands as best management practices (BMPs) for treatment of oil-contaminated stormwater runoff.

RP135 (DRA-1117-746824) Analysis of tire rubber leachate with a bacterial mutagenesis assay.
Start time: 8:00 AM
Benevento, S¹, Draper, A¹, ¹ Trinity College, Hartford, CT, USA
Rubber particles from automobile tires wear off with use and contribute to water pollution as they leach harmful chemicals into the environment. In an effort to examine the effects of these water-soluble chemicals, Salmonella typhimurium was used to assess the mutagenicity of tire rubber leachate. Tire tread particles were leached in hard water for 10 days at room temperature with constant agitation, filtered through a 0.45 m nylon membrane and stored at 4°C until use. The leachate was concentrated 10- and 100-fold with a C-18 solid phase extraction column, extracted into hexane, dried under N₂ and reconstituted in DMSO. Bacterial mutagenesis assays using Ames strains TA 1535 and TA 1538 were performed according to Standard Methods. Briefly, bacteria were pre-incubated in nutrient broth for 12 hr at 37°C with shaking. Then, 0.1 ml of test material (in DMSO), 0.5 ml of rat liver S-9 mixture, and 2.5 ml of melted top agar were added. After 20 min additional incubation, the contents were vortexed, poured on minimal agar plates, and incubated at 37°C for 60 hr before being scored. Revertant colonies were counted and scored against negative control plates (DMSO), and diagnostic mutagens analyzed with each experiment served as positive controls. Evidence suggests that tire rubber leachate requires metabolism to induce mutation and may be mutagenic at elevated concentrations. While no mutagenesis was detected with unconcentrated tire rubber leachate, proportional mutagenesis was observed with 10:1 and 100:1 concentration. With a growing number of automobiles on the road there is a marked increase in the amount of tire rubber particles entering the environment: collecting on roadways as dust and eventually being washed into local waterways. Further work will be directed towards identifying the mutagenic chemical(s) in these particles and may suggest the elimination of toxic compounds in future tire production.

RP136 (BEA-1117-667649) Optimization of USEPA′s Ceriodaphnia dubia diet using response surface methodology.
Start time: 8:00 AM
Beaty, Jr., T^{1, 2}, Zingmark, R¹, ¹ University of South Carolina, Columbia, SC, USA² SCDHEC Bureau of Water, Columbia, SC, USA
The diet that USEPA recommends for Ceriodaphnia dubia is a mixture of the green alga Pseudokirchneriella subcapitata, aqueous extract of cereal leaves (AAE), fish food digestate (FFD) and activated dry bakers yeast, Saccharomyces cerevisiae. We attempted to experimentally find optimum levels of each food, those that would maximize R0, the net reproductive rate. In all experiments, C. dubia were cultured for 11 days according to the USEPA WET methods. We performed nine 24 factorial experiments in which levels of each food were varied independently. Yeast did not affect R0, but the results were inconsistent for the other components. We then performed nine mixture experiments in which the treatments consisted of mixtures of varied proportions of each component. We included yeast in one experiment, and found that the optimum mixture contained no yeast. The data were regressed, plotted as contours on a simplex axis system, and the first partial derivatives of the regression with respect to the parameters was set equal to zero and solved to obtain the coordinates of the optimum proportions. The highest R0 was 80.85 young per female, and was produced by a mixture containing 0.32 g/l FFD, 0.89 g/l AAE, and 6.36X107 P. subcapitata cells/ml. C. dubia were maintained on the optimized diet for over a year alongside C. dubia on the USEPA diet. Neither diet provided consistent reproduction. Time series analysis showed that reproduction was autocorrelated over time.

RP137 (BEL-1117-115307) Acute Toxicity Testing of Fish and Animal Alternatives: Strategies to Implement the 3Rs.
Start time: 8:00 AM
Belanger, S¹, Rawlings, J¹, Carr, G.¹, Gimeno, S², ¹ The Procter & Gamble Company, Cincinnati, OH, USA² The Procter & Gamble Company, Brussels, Belgium
Animal alternatives have traditionally been the province of human safety assessments. The interpretation of the European Directive on the use of laboratory animals (Dir 86/809) and the draft chemical legislation (REACH) is moving the debate to the use of vertebrates in environmental risk assessment as well. Reducing the numbers of animals tested strategically occurs under the umbrella of the 3Rs-Replace, Reduce, and Refine. One goal of an implemented strategy would be to retain, at least, the current level of certainty in the environmental risk assessment process. A research program has been developed to assess the potential use of non-protected egg and embryonic life stages of fish and modify testing and statistical procedures to accommodate the use of fewer fish. This presentation provides an overview of the current avenues followed to implement the 3 Rs: 1) an assessment of alternative testing strategies such as the up and down procedure commonly used in small mammal acute toxicity testing (Bruce 1985; OECD, 2001) modified to accommodate fish and the step-down method proposed by Hutchinson et al. (2004) (reductive measures); 2) an assessment of the potential use of and rationale for fish early life stage (egg and eleutherembryo) acute tests (replacement measure) based on recent studies in our laboratories and reviews of related literature. In order to verify the applicability of these approaches, we are also presenting the outcome of 3) an assessment of the statistical basis for the numbers of fish typically used by aquatic toxicologists, and; 4) an evaluation of a greater role in risk assessments for acute fish toxicity limit tests under certain conditions (a reductive measure) Each of these approaches has value in achieving the above stated goal with an added benefit of potentially increasing speed of assessments due to reduced experimental complexity or shorter test timeframes.

RP138 (TSY-1117-768240) Radiation-induced untargeted germline mutations in Japanese medaka (Oryzias latipes).
Start time: 8:00 AM
Tsyusko, O.¹, Glenn, T.¹, Yi, Yi¹, Hinton, T.¹, ¹ Savannah River Ecology Laboratory, University of Georgia, Aiken, SC, USA
Radiation is well known to induce mutations at or near the sites of interaction with DNA. The frequency of mutations at tandem repeat loci, however, has recently been shown to increase from exposure to radiation and air pollution as a result of untargeted effects. Untargeted mutations represent a major evolutionary force that is only now becoming illuminated and much work remains to be done. Here, we studied germline mutations in Japanese medaka (Oryzias latipes) using microsatellite loci with high mutation rates (0.5–1.0 x 10^-2 mutants per locus per gamete). Females and males of medaka prior to breeding were chronically irradiated at 68 mGy/day in outdoor mesocosms. Mutation rates varied substantially among different loci. The mutation rates at more than 50% of the microsatellite loci were 1.5–4.3 fold elevated in the F1 offspring of the irradiated parents compared with those of unexposed fish. This suggests that exposure to environmentally relevant radiation doses can increase the mutation rate of untargeted microsatellite loci in medaka. Whether radiation-induced increased mutation rates affect the mutation rates of gametes of unexposed mates or persist to F2 and F3 generations in medaka is currently under investigation.

RP139 (VAL-1117-812487) Chlorine toxicity to early life stages of freshwater mussels (Bivalvia: Unionidae).
Start time: 8:00 AM
Valenti, T¹, Cherry, D¹, Neves, R², Kane, C³, ¹ Department of Biology, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, United States² Virginia Cooperative Fish and Wildlife Research Unit, U.S. Geological Survey, Blacksburg, Virginia, United States³ United States Fish and Wildlife Service, State College, Pennsylvania, United States
Chlorine (Cl) is a highly toxic, widely used halogen disinfectant that is present in point source pollution discharges from wastewater treatment plants and industrial facilities. Although it dissipates quickly in natural waters, Cl pollution poses a substantial threat to biota located downstream from these sources due to its continuous discharge. The current United State Environmental Protection Agency freshwater criteria for Cl is 19 ppb total residual Cl (TRC) as a maximum 1-h average concentration, and 11 ppb TRC as a maximum 3-day average; however, toxicological data for unionids were not used to develop these criteria. Declines in the number of species and abundance of mussels have caused concerns, which have become further escalated by recent observations of low recruitment in many assemblages. Previous laboratory studies report that early life stages of freshwater mussels are more sensitive to toxicants than adults. In our study, we conducted acute tests with glochidia from several species, and 21-d bioassays with 2-mo old Epioblasma capsaeformis and 3-, 6-, and 12-mo old Villosa iris juveniles. The mean 24-h LC50 values for glochidia were between 70 and 220 ppb TRC, which are between 2.5 and 37 times higher than those reported in other studies with Ceriodaphnia dubia and Daphnia magna. Significant declines in growth and survivorship were observed in the 21-d test with E. capsaeformis at 20 ppb TRC. Lowest observed adverse effects concentrations for bioassays with juvenile V. iris were higher (30 to 60 ppb TRC) but showed a trend of decreasing toxicity with increased age. Although other factors may affect the population size of the endangered species, such as the availability of fish host, reproductive timing, and brood type, it is likely that toxicological effects also have a substantial impact on recruitment. The results of our study support this as species listed as federally endangered species were substantially more sensitive to Cl exposure than the other species tested.

RP140 (GRU-1117-920996) West Nile virus, mosquito control, and aquatic invertebrates: implications for Pacific Northwest wetlands.
Start time: 8:00 AM
Tamayo, Mariana¹, grue, christian¹, ¹ University of Washington, seattle, WA, USA
Loss of human life due to the rapid spread of West Nile virus across North America has generated increasing pressure to aggressively control mosquitoes, including on national wildlife refuges. Mosquito control using Bacillus thuringiensis israelensis (Bti) had been proposed on Franz Lake National Wildlife Refuge (Washington) to reduce the threat that mosquitoes pose to adjacent landowners. However, there is concern that Bti may adversely affect a variety of fish (e.g., salmonids) and wildlife that feed on non-target invertebrates. We assessed the short-term effects of Bti on the invertebrate communities present in Franz Lake by establishing eight plots (40 m x 6 m separated by a 50 m buffer) along the southern shore of the lake in 2003. We used a spot treatment regime that consisted of three Bti applications (VectoBac-G®) at 9-10 d intervals using a rate of 7.8 kg ha-1 in four of the plots. Benthic and water column samples were collected from all eight plots before and 7 d after treatment. The southern shore of Franz Lake supported a fairly diverse macroinvertebrate community consisting of >40 taxa. Although insect families represented most of the taxa (>50%) found within the lake's shoreline, Oligochaeta and Cyclopoida were the most common taxa. There were no significant differences between the control and treatment plots, both had similar physical variables (water temperature, water depth) and macroinvertebrate communities across the spray events. Our study suggests that using a Bti spot treatment regime of 1-3 applications for one season may be a suitable management tool for some wetlands present on national wildlife refuges to control mosquitoes without having any significant short-term effects on the macroinvertebrate communities. However, the potential for cumulative effects on these wetland communities when exposed to multi-year applications of Bti remains to be determined and warrants further research.

RP141 (BEJ-1116-966208) Utility of a NIST crude oil Water Accommodated Fraction (WAF) as a benchmark for copepod reproductive and population-level toxicity.
Start time: 8:00 AM
Bejarano, A¹, Chandler, G¹, He, L¹, ¹ University of South Carolina, Columbia, SC, USA
Crude oil contamination in coastal ecosystems serves as a source of water-accommodated hydrocarbon fraction (WAF) to sediment and pore-water posing a risk to benthic invertebrates. Experiments were designed to evaluate the NIST crude oil standard as a positive control in chronic WAF testing. NIST standard and South Louisiana crude-oils were used to assess the effects of crude oil-WAF on Amphiascus tenuiremis' life-cycle endpoints, using a 96-well microplate test. Briefly, 24-hour hatched nauplii were followed to adulthood (ni≥120 nauplii/treatment) in individual glass-coated microplate wells containing 200 L of solution. Treatments consisted of 10%, 30%, 50% and 100%-WAF, with seawater used as a control. Nauplii were monitored through development to adulthood, and virgin copepods were mated pair wise in wells containing original treatments. Toxicological endpoints included mortality, development, sex ratios, fertilization success, viable production and population growth trajectories. In exposures to 100% NIST and Louisiana-WAF, naupliar survival was significantly reduced (73±6% and 32±5%, respectively; p<0.05), relative to controls (92±1% and 88±3%, respectively), and copepodite survival was only reduced in the 50% Louisiana-WAF (88±3%; p=0.04) relative to controls (98±3%). Developmental curve analysis showed that nauplii in the 10% NIST and Louisiana-WAF developed into copepodites at a faster rate than controls, while nauplius the 50% NIST and Louisiana-WAF, and 100%-NIST WAF developed at a slower rate. Although development rate in 100% Louisiana-WAF was similar to that of controls, nauplii showed a consistent 1.4 day delay in development. Developmental delays/enhancements in the copepodite-to-adult window were also observed in exposures to both crude oil WAFs. None of the WAFs had any significant effects on offspring production by mating pairs able to reproduce (p>0.05). However, reproductive failure was increased by 30% and 41% in the 30% and 100% Louisiana-WAF, respectively. Leslie matrix model significantly projected lower naupliar abundance through 3-generations in exposures to 100%- NIST WAF and in all Louisiana WAFs, compared to controls. Chemistry analysis indicated that naphthalene was the most abundant PAH (>50%) in both WAFs.

RP142 (BRY-1117-832601) Occurrence and effects of polycyclic aromatic hydrocarbons (PAHs) originating from coal tar sealed parking lots.
Start time: 8:00 AM
Bryer, P.¹, Scoggins, M.², McClintock, N.², ¹ The Institute of Environmental and Human Health, Texas Tech University, Lubbock, TX, United States² Watershed Protection Department, City of Austin, Austin, TX, United States
Coal tar pavement sealants have recently been recognized to have significant lethal effects on biota. Laboratory studies have shown toxicity of coal tar sealant particles to aquatic macroinvertebrates, Hyalella, and Xenopus larvae. Additional studies have indicated that coal tar pavement sealant can contribute significant levels of polycyclic aromatic hydrocarbons (PAHs) to storm water run-off. We investigated whether this run-off and potential toxic effects were seen in the streams of urban Austin, TX. Using aerial photography we located parking lots adjacent to five streams that were apparently sealed with a coal tar product. We sampled sediment and biological communities above and below the point source for the selected parking lot, resulting in five downstream treatment sites and 5 upstream reference sites. Riffle and pool communities from each site were used to evaluate noted differences in total PAH concentrations (average increase of 2 orders of magnitude) above and below these point-sources. Analysis of the species abundance data from the stream pools indicates a significant decrease in community health. Significant changes in the number of non-insect taxa, intolerant taxa, abundance, and richness were found between the reference and treatment sites (p <0.05 Wilcoxon Sign Rank Tests). Riffle communities showed much less of a pattern than pool communities, with only richness showing a significant difference between treatments.

RP143 (JOC-1117-817893) Central Halifax Harbour: body burden of contaminants and biological effects in mussels.
Start time: 8:00 AM
Gagne, F¹, Yeats, P², Hellou, J², ¹ Environment Canada, Montreal, Quebec, Canada² Fisheries and Oceans, Dartmouth, Nova Scotia, Canada
An investigation of contaminants and biological effects in mussels from Halifax Harbour, Nova Scotia, Canada, focused on the city foreshore, around a previously identified hotspot. It extended the spatial collection of mussels over a 6 km stretch where consolidation of sewers and the construction of a sewage treatment plant (STP) is ongoing. The aim of the study was to compare the body burden of PAH, DDT, coprostanol and elements in mussels, to biological parameters examined previously, such as condition and gonad indices, sex ratio, stress on stress response, i.e. survival in air, and to additional biochemical indicators of mussels health analysed in gills, digestive gland and gonad tissues. These biomarkers included total sugar content of gonads, total lipid in gonads, gonad mitochondrial electron transport activity, digestive gland mitochondrial electron transport activity (GETA), gonad lipid peroxidation, gill lipid peroxidation and digestive gland heme oxidase activity. A comparison is made to the previously pinpointed hotspot. A link is drawn between longer survival in air, higher lipid content, lowest condition index, concentrations of coprostanol, PAH, DDE along with higher levels of Sn and Cd in mussels near a container pier. At the opposite end of the area, shorter survival time, lower lipid content, higher oxidative stress and metabolism, GETA, levels of coporostanol, PAH, DDE, Ag, Cu, Fe and P were observed near a major sewage effluent. These results along with earlier studies linking chemicals with particles suggest that the STP discharge into the deeper parts of the central harbour will have a positive influence on the health of shoreline mussels ingesting particle bound chemicals.

RP144 (FAR-1117-835530) Comparative evaluation of the efficacy of acute and chronic sublethal sediment tests for assessing sediment quality.
Start time: 8:00 AM
Farrar, J¹, Lotufo, G¹, McNemar, C², ¹ US Army ERDC, Vicksburg, MS, USA² ASI Corporation, Vicksburg, MS, USA
Chronic sublethal tests are expected to be more sensitive indicators of the detrimental effects of low to moderate levels of contamination due to the longer exposure duration and the measurement of sublethal responses such as growth and reproduction. The typically higher sensitivity of sublethal tests has been demonstrated for freshwater toxicity tests but has not been sufficiently demonstrated for marine/estuarine tests. Because the cost associated with conducting chronic tests is substantially higher compared to acute evaluations, it is necessary to compare the efficacy of the chronic and acute tests in detecting biological effects before promoting the use of this more expensive approach. Due to the demonstrated differences in the ability of the chronic sublethal tests available to detect low to moderate levels of contamination, the selection of a test method can have profound implications in the decision making process. To evaluate the usefulness of chronic sublethal sediment tests as indicators of detrimental environmental effects in comparison to acute tests, field-collected sediments, each predominantly containing a contaminant class (i.e., PAHs, PCBs, heavy metals) were obtained and a dilution series of each sediment prepared using appropriate clean sediment. Each dilution series was used to compare three widely utilized sediment tests, the Leptocheirus plumulosus 10-d acute test and the Leptocheirus plumulosus and the N. arenaceodentata 28-d chronic sublethal tests. Results demonstrate that chronic sublethal tests are not consistently more responsive to effects elicited by low to moderately contaminated sediments. In some instances acute tests were equally or more responsive to contaminants relative to chronic exposures. Increased responsiveness of the chronic tests appear to be contaminant dependent. When selecting a test method, careful consideration should be given to the relative responsiveness of the species to the contaminant of concern and the selection should be evaluated in light of the goals of the research project.

RP145 (KNO-1117-569112) Quantifying DNA Damage in Frogs from Agricultural Areas of Southwestern Ontario, Canada.
Start time: 8:00 AM
Ferguson, R¹, Pauli, B¹, Martin, P², McDaniel, T², Marvin, C³, Knopper, L⁴, ¹ National Wildlife Research Centre, Canadian Wildlife Service, Environment Canada, Ottawa, ON, Canada² Canadian Wildlife Service, Environment Canada, Burlington, ON, Canada³ National Water Research Institute, Environment Canada, Burlington, ON, Canada⁴ Jacques Whitford, Ottawa, ON, Canada
Genotoxicity in wildlife species as a result of non-target pesticide exposure has been reported in numerous studies. We examined whether field exposure to agricultural chemicals might result in measurable DNA damage in ranid amphibians inhabiting areas of intensive corn-soybean agricultural. To accomplish this we measured DNA damage in Rana pipiens (Northern leopard frogs) and Rana clamitans (Green frogs) collected in agricultural ponds and drainage ditches in southwestern Ontario. Blood from 72 adult frogs was collected between July and October, 2004, from 11 different sites: two control sites (without agricultural influence), one agricultural control site (marsh located within an agricultural area), and eight agricultural sites. Whole blood was diluted in a cryopreservant and flash frozen in a vapor phase nitrogen dewar and subsequently stored at -80C. At a later date, blood was thawed and DNA damage (single and double DNA strand breaks) was assessed using the alkaline Comet assay. Water collected at the same sites as the frogs had measurable levels of atrazine, metolachlor, nutrients, and heavy metals in the agricultural and agricultural control sites, whereas these contaminants were very low or not detected in control sites. Because of this shared contamination, agricultural and agricultural control data were pooled and compared to control data. Measures of DNA damage using the Comet assay (tail length, % DNA in the tail) in frogs from agricultural sites was significantly greater than in frogs from control sites (p = 0.046, 0.08). The specific cause of the observed genotoxic damage is not known but our results suggest that frogs living in agricultural areas are exposed to genotoxins.

RP146 (FIS-1117-730454) Brain gene expression in mummichog (Fundulus heteroclitus) populations using metabolic microarrays.
Start time: 8:00 AM
Fisher, M¹, Oleksiak, M¹, ¹ North Carolina State University, Raleigh, NC, 27606
Knowledge of the effects of chronic pollution in the brain is critical since the brain is required for specialized information processing and signaling, yet its lipid-rich make-up and high metabolic demands make it especially vulnerable to neurotoxicants. How does gene expression in the brain vary among polluted and reference populations and also among individuals? This work uses a targeted array of metabolic genes to identify differences in gene expression among a Fundulus population chronically exposed to environmental pollutants (Elizabeth River, VA) and 2 reference Fundulus populations (Magnatha, VA and Manteo, NC) that were field collected and common gardened. Brain RNAs from 15 individuals (5 individuals per population) were isolated, amplified, and hybridized to arrays using a loop design. Differences in gene expression among polluted and reference populations will suggest mechanisms for the brain to cope with pollutants.

RP147 (MIL-1117-828820) Enrichment of xenobiotic-degrading bacteria using a new in situ monitoring device.
Start time: 8:00 AM
Miller, T¹, Halden, R¹, ¹ Center for Water and Health,Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
Natural populations of bacteria are often difficult to study due to problems of growing fastidious microorganisms in the laboratory and the overall expense of field studies. To address this concern we have constructed the In Situ Microcosm Array (ISMA), a field-deployable device designed to capture, monitor and enrich for microorganisms in their natural habitat. The device contains 96 capillary microcosms that are packed with sterile filter material soaked in chemical substrates, activators or inhibitors. As ambient water is pumped through the device, microorganisms are captured by the filter material and allowed to interact with chemical substrates. The overall response of the community is then measured using a variety of common post-processing assays and further enrichment of captured organisms is performed. To test the utility of the device, we have chosen as our model system the dioxin-mineralizing bacterium, Sphingomonas wittichii RW1. Using a monoculture of S. wittichii RW1, the ISMA was able to homogenously capture RW1 cells across all 96 microcosms with a standard deviation of less than 5%. In individual experiments, positive dose-response curves were obtained for various carbon substrates versus RW1 abundance, indicating that the chemicals presented in the microcosms were available to captured bacteria. Using a mixed community of bacteria, including S. wittichii RW1, selective enrichment of RW1 in dibenzofuran-amended microcosms was achieved successfully as measured by denaturing gradient gel electrophoresis (DGGE). The effect of various other chemical substrates (e.g., biphenyl, benzoate, acetate) or inhibitors (e.g., antibiotics and heavy metals) on bacterial community structure was also studied in individual microcosms of the microcosm array. Results from these experiments indicate that the ISMA represents a valuable new tool for cultivating and studying microorganisms in situ under experimental conditions approaching those extant in their natural habitat.

RP148 (COO-1117-719326) The use of cholinesterase activity and ecologically-relevant behavioral parameters to indicate chlorpyrifos exposure in the Asian clam, Corbicula fluminea.
Start time: 8:00 AM
Cooper, N¹, Bidwell, J¹, ¹ Oklahoma State University, Stillwater, OK, 74075
This study assessed the effects of an organophosphorous pesticide, chlorpyrifos, on cholinesterase activity, siphoning and burrowing ability in the Asian clam, Corbicula fluminea. Clams were exposed to concentrations of the pesticide ranging from 0.05 to 50 mg/L in a series of 96-h static bioassays. Those organisms exposed to chlorpyrifos concentrations at or above 3.13 mg/L avoided exposure through valve closure during the 96-h test period, with no resultant effects on cholinesterase activity or behavior. Similarly, no effect was observed at low-test concentrations ranging from 0.05 to 0.1 mg/L, even though clams actively siphoned in these treatments. Asian clams exposed to the mid-range of concentrations, 0.5 to 1.0 mg/L, experienced a significant reduction in cholinesterase activity and a reduced capacity to burrow into the substrate. While these data indicate that cholinesterase activity in C. fluminea could be used as a biomarker of organophosphorous pesticide exposure, valve closure can clearly influence exposure profiles and biomarker response.

RP149 (OST-1117-767634-1) Striped bass habitat use in the San Francisco estuary determined using otolith microchemistry techniques.
Start time: 8:00 AM
Ostrach, D¹, Phillis, C², Weber, P³, Ingram, B², Zinkl, J¹, ¹ University of California at Davis, Davis, CA, USA² University of California at Berkeley, Berkeley, CA, USA³ Lawrence Livermore Laboratory, Livermore, CA, USA
Habitat use has been shown to be an important factor in the bioaccumulation of contaminants in striped bass. This study examines migration in striped bass as part of a larger study investigating maternal transfer of xenobiotics to progeny in the San Francisco Estuary. Habitat use, residence time and spawning migration over the life of females was studied (n = 50). Female striped bass were collected on the Sacramento River during the spawning runs of 1999-2001. Additonal samples were obtained during the 2005 spawning season from the San Joaquin River and nearshore Pacific Ocean. Otoliths were removed, processed and aged via otolith microstructure. Subsequently, otoliths were analyzed for strontium/calcium (Sr/Ca) ratio using an electron-microprobe to measure salinity exposure thus distinguishing freshwater, estuary, and marine habitat use. In addition, a subset of otoliths were subjected to LA-ICPMS and MC-LA-ICPMS techniques to verify electron probe findings and to gain additional elemental and isotopic data in order to refine temporal and spatial habitat use. Salinity exposure during the last year before capture was examined more closely for comparison of habitat use by the maternal parent to contaminant burden transferred to progeny. The Sr/Ca data demonstrate a wide range of migratory patterns. Age of initial ocean entry differs among individuals before returning to freshwater, presumably to spawn. Some fish reside in freshwater year-round, while others return to more saline habitats and make periodic migrations to freshwater. Frequency of habitat shifts and residence times differs among fish, as well as over the lifetime of individual fish. However, not all fish migrated to freshwater to spawn in the previous year. Results from this investigation will be combined with contaminant and histological developmental analyses to better understand the bioaccumulation of contaminants and the effects they and habitat use have on fish populations in the San Francisco Estuary.