151 (THE-1118-337607) Monitoring metals: mussels or passive samplers? Developing appropriate solutions to European Water Directive requirements.
Start time: 1:50 PM
Thebault, H¹, Griscom, S^{1, 3}, Desnues, A¹, Gonzalez, J-L², Andral, B², Sauzade, D², Kantin, R², Shine, J³, Senn, D³, Lewis, C³, ¹ Institut de Radioprotection et de Sûreté Nucléaire, La Seyne sur Mer, France³ Harvard School of Public Health, Boston, Ma, USA² Institut français de recherche pour l'exploitation de la mer, La Seyne sur Mer, France
Measuring trace metals concentration in marine waters in a way that is ecologically relevant is a difficult goal. New European Framework Water Directives require that, in order to follow progress towards its ambitious objectives: to reach 'good' chemical status for coastal water masses by the year 2015, concentrations of various dissolved 'contaminants of concern' must be measured on a regular basis. The French Mussel-watch program has monitored large-scale, long-term trends in metal, organic, and radioactive contaminants in coastal waters for over 25 years. This program has helped to assess efforts to reduce contaminant input as well as to focus efforts on persistent toxic matter. Unfortunately, tissue-residue data cannot be used to directly measure contaminant concentrations in water, an essential element of the new European Directives for pollution monitoring. A new inexpensive passive equilibrium sampler is presently being tested in the field to determine it's effectiveness in satisfying some of the new Directive requirements. In collaboration with Harvard School of Public Health and IFREMER, IRSN is testing this new sampler (the Gellyfish), which appears promising as an effective tool to measure a bioavailable fraction of trace metals in seawater: the free-ion metal concentration. Three separate field projects have facilitated the testing: 1. MYGELEX (MYtilus GELlyfish Experiment), a one-year field experiment in which monthly metal concentrations are concurrently measured in caged mussels, Gellyfish, dissolved and particulate phases; 2. COMPAS (COMparison of Passive Samplers), a 7 week deployment that compared metal concentrations in Gellyfish and DGT (Diffusive Gradient Thin-film) samplers; and, 3. MYTILOS, a project in which Gellyfish were deployed alongside caged mussels at 30 sites in the island and coastal areas of Spain and Italy. The Gellyfish may provide insight into DOC-complexation with trace metal and unravel uptake routes of metal into marine organisms. Further, the low cost of Gellyfish may allow countries lacking in research funds, the ability to afford monitoring.

152 (MEB-1117-844014) Cadmium risks to freshwater life: predicted low-effect values in ambient waters based upon laboratory and field studies.
Start time: 2:10 PM
Mebane, C¹, ¹ U.S. Geological Survey
In 2001, the U.S. Environmental Protection Agency (EPA) released updated aquatic life criteria for cadmium (Cd). Since then additional data on the effects of Cd to aquatic life have become available from studies supported by the EPA, Idaho Department of Environmental Quality (IDEQ), and the U.S. Geological Survey (USGS), among others. Updated data on the effects of Cd to aquatic life were compiled, reviewed, and low-effect values were estimated. Low-effect values ("criteria") were calculated using EPA's guidelines for deriving numerical national water quality criteria for the protection of aquatic organisms. Suitable data on the acute effects of Cd to North American freshwater species were located for 60 species representing 53 genera and 31 families; chronic data were located for 28 species in 21 genera and 17 families. The four most sensitive genera to acute exposures were, in order of increasing Cd resistance, Oncorhynchus (Pacific trout and salmon), Salvelinus (charr trout), Salmo (Atlantic trout and salmon), and Cottus (sculpin). The four most sensitive genera to chronic exposures were Hyalella (amphipod), Gammarus (amphipod), Salvelinus, and Cottus. Using the updated data sets, hardness dependent criteria equations were calculated for acute and chronic exposures to Cd. At a hardness of 50 mg/L as calcium carbonate, the resulting acute and chronic criteria values for filtered samples were 0.75 g/L and 0.38 g/L Cd respectively. Using data that were independent of those used to derive the criteria, the criteria conditions were evaluated to estimate whether adverse effects to the biological integrity of natural waters or to species listed as threatened or endangered in Idaho were expected. The vast majority of data indicated that criteria conditions were unlikely to contribute to any overt, adverse effects to either biological integrity or listed species. Some data suggest subtle, adverse effects such as behavioral changes or swimming performance of fish were possible following long-term exposures to low levels of Cd. Careful biological monitoring of invertebrate and fish assemblages would be prudent in the vicinity of discharges containing Cd concentrations which could result in receiving waters approaching criteria.

153 (GRE-1117-816574) Assessment of mixture toxicity of metals, PAHs and oxyPAHs to Daphnia magna: Synergistic toxicity via ROS.
Start time: 2:30 PM
Xie, F¹, Koziar, S¹, Lampi, M¹, Dixon, D¹, Norwood, W², Borgmann, U², Huang, X¹, Greenberg, B¹, ¹ Department of Biology, University of Waterloo, Waterloo, ON, Canada² Environment Canada, National Water Research Institute, Burlington, ON, Canada
Metals, polycyclic aromatic hydrocarbons (PAHs) and their derivatives are commonly present in complex mixtures in the environment. Strikingly, little is known about mixture toxicity and specific mechanisms of mixture toxicity. Cu, Ni and Cd were selected, representing a highly redox-active, a moderately redox-active and a non-redox active metal, respectively. We have found synergistic effects for the combinations of Cu or Ni with phenanthrenequinone (PHQ), a major photoproduct of phenanthrene (PHe). In contrast, additive toxicity was observed in mixtures of Cd plus PHQ, as well as in mixtures of Cu plus PHE. The increased toxicity of Cu plus PHQ is physiologically based because assimilation of Cu was similar with or without PHQ. We have shown using the dichlorofluorescein (DCF) fluorescence assay that Cu and Ni alone induce ROS formation in D. magna, whereas PHQ and Cd had no effect on ROS production. Relative to the individual metals, enhanced ROS production was observed in D. magna treated with mixtures of Cu plus PHQ, and Ni plus PHQ, but not with Cd plus PHQ mixtures. Furthermore, the increased toxicity and RIS production were attenuated by the antioxidants L-ascorbic acid, beta-carotene or dimethylthiourea (DMTU). The results indicate that there are potential toxic interactions between redox-active metals and modified PAHs, and provide evidence for a ROS-mediated mechanism for mixture toxicity.

154 (VAN-1117-847344) Validation of Biotic Ligand Model performance in extremely hard surface waters of the arid southwest.
Start time: 2:50 PM
Van Genderen, E¹, Gensemer, R¹, Santore, R², Ramage, K³, Curley, E³, Meyerhoff, R⁴, ¹ Parametrix, Inc., Albany, OR, USA² HydroQual, Inc., Camillus, NY, USA³ Pima County Wastewater Management, Tuscon, AZ, USA⁴ Camp, Dresser & McKee, Denver, CO, USA
Municipal wastewater treatment facilities in the arid western U.S. often face difficulties in complying with their NPDES discharge permits resulting from the unique hydrologic and geochemical conditions of effluent-dependent waters (i.e., river flow generated entirely from effluent discharge). In part, this is because the scarcity of upstream flows limits discharge mixing zones; but also because of the unique geochemical characteristics of these waters. Acute copper water-effect ratios (WER) were derived with three species of aquatic organisms (Pimephales promelas, Ceriodaphnia dubia, and Daphnia pulex) using seven effluent-dependent waters ranging in hardness from 150 to over 1000 mg/L (as CaCO₃) under base stream flow conditions. Additional WERs were derived using only C. dubia for three of the sites during elevated flow conditions. The results of this study were used to quantify the influence of extremely hard waters on metal toxicity, and to help validate the Biotic Ligand Model (BLM) for use in predicting acute copper toxicity and WERs under the unique ionic composition of these test waters. WER values ranged from 2 to 15 under base flow conditions and were typically greater for C. dubia and D. pulex compared to P. promelas. Base flow WERs were typically two-times greater than WERs produced in site waters collected during elevated flow conditions. Flow related effects on WER values were likely due to dilution of water quality constituents such as hardness, alkalinity and dissolved organic carbon. A majority of BLM predictions of median-lethal concentrations and WERs were within acceptable deviations of observed values for all species. However, improvements to model predictions were noted by including Mg-biotic ligand interactions for invertebrates and copper complexation by suspended solids.

(58561) Break.
Start time: 3:10 PM

155 (GAL-1117-860194) The effects of natural organic matter on fish gill epithelia.
Start time: 3:50 PM
Galvez, F. ¹, Donini, A.¹, Diao, L. ¹, Playle, R.², Smith, S.³, Wood, C.¹, ¹ Department of Biology, McMaster University, Hamilton, Ontario, Canada² Department of Biology, Wilfrid Laurier University, Waterloo, Ontario, Canada³ Department of Chemistry, Wilfrid Laurier University, Waterloo, Ontario, Canada
Natural organic matter (NOM) exhibits a high degree of chemical heterogeneity, conferring on it different abilities to complex metals. However, little is known of the direct effects of NOM alone on epithelial surfaces. We used in vitro and in vivo approaches to study the influence of different sources of NOM on the electrophysiological characteristics of the fish gill epithelium. NOM isolated from nine different sources in Ontario, as well as a commercially available humic acid (Aldrich), were tested for their effects on transepithelial potential (TEP) and resistance (TER) on a fish gill epithelium in primary culture on filter supports. Ion activities in the different waters were also measured using ion-selective electrodes to assess the relative chelating abilities of each source of NOM. NOM derived from allochthonous sources (Four Mile Creek, Talon Lake, Trout Lake, Luther Marsh and Sanctuary Pond) resulted in significant changes to the transepithelial potential (TEP) across a cultured surrogate model of the rainbow trout gill. In comparison, NOM derived from autochthonous sources (Dundas Sewage Treatment Plant, Grand River, Lake Erie and Lake Nippissing) elicited only marginal effects on TEP across the epithelium. NOM also influenced TEP in vivo in a similar fashion. The magnitude of these NOM-induced changes in TEP was related to the aromaticity of the NOM, although two of the NOM samples were particularly strong chelators of calcium, which in these cases could explain their abilities to hyperpolarize the gill epithelium. This talk will discuss the implications of these direct effects of NOM at the fish gill to the future development of environmental risk models for metals such as silver (Supported by Kodak Canada and NSERC).

156 (BRI-1118-265294) The toxicity of copper to the snail, Lymnaea stagnalis: a physiological explanation for its high sensitivity.
Start time: 4:10 PM
Brix, K^{1, 2}, Ebanks, S², Grosell, M², ¹ Ecotox, Key Biscayne, FL, USA² RSMAS, University of Miami, Miami, FL, USA
We have previously demonstrated the pulmonate snail, Lymnaea stagnalis, to be the most sensitive organism tested to date for Pb, with effects on growth in juvenile snails at 4 g l^-1 Pb. The explanation for this hyper-sensitivity involves the extremely high Ca²⁺ demand of this organism for shell formation and the effect of Pb on Ca²⁺ uptake. Interestingly, this snail also appears to be very sensitive to Cu, with a similar effect on growth in juvenile snails at a waterborne Cu concentration of 3 g l^-1. We are investigating the physiological mechanisms by which Cu inhibits juvenile snail growth. Despite the snail having similar sensitivity to both Cu and Pb for the same endpoint, the mechanisms of action are quite different for the two metals. The other major component of shell formation is CO₃^2-. While some CO₃^2- for shell formation appear to arise from endogenous CO2 production, it is clear that external HCO₃^- also provides part of the substrate needed for shell formation. Regardless of the source of CO₂, the enzyme carbonic anhydrase is required for CO₃^2- formation and inhibition of this enzyme by Cu is the hypothesized site of action. We also explore the applicability of existing biotic ligand models for predicting Cu toxicity to snails, given their fundamentally different physiology compared to invertebrates (daphnids) for which the biotic ligand model has been developed.

157 (PAN-1117-741205) Hydromineral balance in the marine gulf toadfish exposed to nickel via two routes.
Start time: 4:30 PM
Pane, E¹, McDonald, M², Curry, H², Wood, C³, Grosell, M², ¹ Monterey Bay Aquarium Research Institute, Moss Landing, CA, USA² Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL, USA³ McMaster University, Hamilton, ON, Canada
The effects of acute Ni exposure on the marine gulf toadfish (Opsanus beta) were investigated via separate exposures to waterborne nickel (Ni) and arterially infused Ni. Of the plasma electrolytes measured after 72 h of waterborne exposure (12,640 and 35,580 g Ni/L in full SW), only plasma [Ca²⁺] was significantly impacted (55% decrease at both exposure concentrations). At both exposure concentrations, plasma [Ni] was regulated for 24 h, after which time linear accumulation occurred until terminal sampling at 72 h. Hydromineral balance in the intestinal fluid (IF) was markedly impacted, with Na⁺, Cl^-, SO₄^2-, K⁺ and Mg²⁺ concentrations elevated after 72 h of exposure to both waterborne concentrations, suggesting Ni-induced damage to both intestinal water and electrolyte transport. Ni accumulation in both the intestine and IF was substantial following waterborne exposure. Arterial Ni infusion (0.40 mol Ni/kg/h) resulted in an increased [Na⁺] and plasma osmolality relative to saline-infused toadfish. Additionally, urine osmolality was significantly elevated by Ni infusion. Perturbation of hydromineral balance of intestinal fluids following Ni infusion was specific only to Na⁺ (significantly elevated by Ni infusion) and Mg²⁺ (significantly decreased by Ni infusion). Ni accumulation via infusion was only moderate in the intestine and non-existent in the IF. Ni accumulation in all tissues save the kidney was substantially lower following infusion than following waterborne exposure. Remarkably, though, the kidney accumulated an almost identical amount of Ni following Ni infusion and waterborne exposure at both Ni concentrations, suggesting either homeostatic control or a passively achieved maximal level sustainable by the toadfish kidney. (Supported by NSERC, NiPERA, ICA, CDA, ILZRO, Teck-Cominco, Noranda-Falconbridge, Inco, SEB Travel Grants, and the SETAC/ICA Chris Lee Award).

158 (BIE-1117-815169) Differences in gill chloride uptake by freshwater fishes- Implications for silver toxicity.
Start time: 4:50 PM
Bielmyer, G.¹, Brix, K.^{1, 2}, Grosell, M.¹, ¹ University of Miami, Miami, Fl, USA² EcoTox, Miami, Fl., USA
In freshwater teleosts, the primary mechanism of acute silver toxicity is branchial Na+/K+ ATPase and carbonic anhydrase inhibition, leading to net Na+ and Cl- loss. External Cl- protects Oncorhychus mykiss, against silver toxicity presumably by complexation to form AgCl. However, there are important exceptions because the same AgCl complex does not appear to influence silver sensitivity for Anguilla anguilla and Pimephales promelas. We hypothesize that differences in protective effects of Cl- is due to differing requirements or mechanisms for Cl- uptake among fish species. Fish, which are not dependent on branchial Cl- uptake, perhaps obtaining chloride through the diet, may not be sensitive to silver-induced inhibition of active chloride uptake at the gill. To test this hypothesis, we exposed Danio rerio, which rely on Cl- uptake across the gills, Fundulus heteroclitis, which does not take up Cl-, and P. promelas, in which Cl- uptake has yet to be measured, to ionic silver in waters of varying [Cl-]. The 96-h LC50 values of F. heteroclitis exposed to AgNO3 in soft water with and without 1 mM KCl were 1.20 and 3.88 g/L, respectively. The 96-h LC50 values of P. promelas exposed under the same conditions were 2.32 and 2.67 g/L, respectively. Based on these results, increasing external Cl- concentration did not offer protection against ionic Ag toxicity to F. heteroclitis or P. promelas. Results from D. rerio are still being analyzed but we anticipate protective effects of Cl- in this fish, which rely on Cl- uptake across the gills. While the lack of Cl- protection in F. heteroclitus is consistent with lack of Cl- uptake, it is unknown at present whether P. promelas exhibits branchial Cl- uptake or perhaps posses a Cl- uptake pathway, less sensitive to silver. Ongoing studies are addressing the issue of Cl- transport in P. promelas.

159 (AAA-1117-802093) Nickel speciation and toxicity in spiked European surface waters.
Start time: 5:10 PM
De Schamphelaere, K¹, Van Laer, L², Smolders, E², Playle, R³, Muyssen, B¹, Klinck, J³, Janssen, C¹, ¹ Ghent University - Laboratory of Environmental Toxicology and Aquatic Ecology, Gent, Belgium² KU Leuven - Laboratory of Soil and Water Management, Leuven, Belgium³ Wilfried Laurier University - Biology Department, Waterloo, ON, Canada
Six natural surface waters varying in pH (6.1-8.1), water hardness (15-218 mg CaCO₃/L), DOC (3.2-25.9 mg/L), and total alkalinity (2.3-144 mg CaCO₃/L) were sampled. DOC was mainly of a terrestrial origin as indicated by McKnights fluorescence indexes of about 1.4. Those waters were spiked with a range of Ni concentrations and subsequently subjected to speciation measurements and acute and chronic toxicity tests with Ceriodaphnia dubia. Free Ni²⁺ concentrations were determined with a Donnan-membrane technique. Overall, the fractions of free Ni²⁺ (Ni²⁺/dissolved Ni)varied between 4 and 60% over the concentrations range investigated, i.e. 3 to 150 ug Ni/L . The fraction of free Ni²⁺ increased within increasing hardness and decreasing pH. The fraction free Ni²⁺ was unaffected by equilibration time after spiking (2 hours - 7 days). Toxicity experiments yielded 48h-LC50s between 35 and 183 ug Ni/L and reproductive 10d-EC50s between 4.9 and 68 ug Ni/L. Linear relations with DOC explained 86% and 82% of the variability in 48h-LC50s and 10d-EC50s, respectively. UV-absorbance properties of the DOC could not explain additional variability. This indicates the important role of DOC-concentration in reducing Ni toxicity at low Ni concentrations. Ratios of 48h-LC50s to 10d-EC50s were between 1.5 and 8.0 and significantly increased with increasing alkalinity. This is explained by an increased chronic toxicity at higher alkalinity levels. These results stress the importance taking into account the effects of parameters such as pH, hardness, DOC and alkalinity in aquatic risk assessment of Ni.