The present study measured the occurrence, distribution, and bioaccumulation of fluoxetine in samples of water, polar organic chemical integrative sampler (POCIS), sediment, and caged freshwater mussels at stream sites near a municipal wastewater treatment facility effluent discharge. We assessed the relation of the environmental concentrations to reproductive endpoints in mussels in acute laboratory tests. Concentrations of fluoxetine in water and POCIS samples were similar (<20% difference) within each site and were greatest in the effluent channel (104–119 ng/L), and decreased at 50 m and 100 m downstream. Likewise, concentrations of fluoxetine in sediment and mussel (Elliptio complanata) tissue were greatest in the effluent channel (17.4 ng/g wet wt for sediment and 79.1 ng/g wet wt for mussels). In 96-h lab tests, fluoxetine significantly induced parturition of nonviable larvae from female E. complanata exposed to 300 µg/L (p = 0.0118) and 3,000 µg/L (p < 0.0001) compared to controls. Fluoxetine exposure at 300 µg/L (p = 0.0075) and 3,000 µg/L (p = 0.0001) also resulted in stimulation of lure display behavior in female Lampsilis fasciola and Lampsilis cardium, respectively. In male E. complanata, 3,000 µg fluoxetine/L significantly induced release of spermatozeugmata during a 48-h exposure. These results suggest that fluoxetine accumulates in mussel tissue and has the potential to disrupt several aspects of reproduction in freshwater mussels, a faunal group recognized as one of the most imperiled in the world. Despite the disparity between measured environmental concentrations of fluoxetine and effects concentrations in our short-term tests with these long-lived animals, additional tests are warranted to evaluate the effects of long-term exposure to environmentally relevant concentrations and critical lifestages (e.g., juveniles). Environ. Toxicol. Chem. 2010;29:1311–1318. © 2010 SETAC

Chemical contaminants are among many potential factors involved in the decline of freshwater mussel populations in North America, and the effects of pesticides on early life stages of unionid mussels are largely unknown. The objective of this study was to determine the toxicity of technical‐grade current‐use pesticides to glochidia and juvenile life stages of freshwater mussels. We performed acute toxicity tests with glochidia (five species) and juveniles (two species) exposed to a suite of current‐use pesticides including herbicides (atrazine and pendimethalin), insecticides (fipronil and permethrin), and a reference toxicant (NaCl). Because of limited availability of test organisms, not all species were tested with all pesticides. Toxicity tests with fungicides (chlorothalonil, propiconazole, and pyraclostrobin) were performed with one species (Lampsilis siliquoidea). Lampsilis siliquoidea glochidia and juveniles were highly sensitive to the fungicides tested but the technical‐grade herbicides and insecticides, at concentrations approaching water solubility, were not acutely toxic to this or the other unionid species. In a 21‐d chronic test with four‐month‐old juvenile L. siliquoidea, the 21‐d median effective concentration (EC50) with atrazine was 4.3 mg/L and in atrazine treatments ≥3.8 mg/L mussel growth was significantly less than controls. The relatively high sensitivity of L. siliquoidea to chlorothalonil, propiconazole, and pyraclostrobin is similar to that reported for other aquatic organisms commonly used for toxicity testing. The relative risk associated with acute exposure of early life stages of mussels to technical‐grade atrazine, pendimethalin, fipronil, and permethrin is likely low; however, survival and growth results with juvenile L. siliquoidea indicate that chronic exposure to high concentrations (≥3.8 mg/L) of atrazine may have the potential to impact mussel populations and warrants further investigation.

Toxins from the dinoflagellate Gymnodinium breve were traced through experimental food chains from dinoflagellates, through copepod grazers, to juvenile fish. The generality of this food web transfer was demonstrated using three different combinations of copepods and juvenile fish during different seasons. Fish were not exposed directly to the toxic dinoflagellates but were fed toxin-laden copepods in order to examine sublethal vectorial intoxication. Toxins were shown to move from fish viscera to muscle tissue within periods of 2–6 h to 25 h. A new toxin detection method was used in this first stepwise demonstration of multi-trophic-level intoxication of a planktonic food chain by G.breve. Micellar electrokinetic capillary electrophoresis with laser-induced fluorescence allowed measurements of toxins at trace levels and nanoliter-sized volumes critical for planktonic food web transfer studies.