Fluoxetine alters adult freshwater mussel behavior and larval metamorphosis.

We used acute and partial-lifecycle tests to examine the effects of the pharmaceutical fluoxetine on freshwater mussels (Unionida). In acute tests lasting 24-48 h, we determined median effective concentrations (EC50s) for fluoxetine with larval (glochidia viability) and juvenile (survival) life-stages of fatmucket (Lampsilis siliquoidea) and black sandshell (Ligumia recta). In a 28-d behavioral test we exposed brooding adult female wavy-rayed lampmussels (Lampsilis fasciola) to 0.37 and 29.3 µg/L fluoxetine to determine effects on adult behavior (foot protrusion, mantle lure display and glochidia parturition). We also assessed the effects of 24-h exposure of 1 and 100 µg/L fluoxetine on glochidia viability duration and metamorphosis success for the wavy-rayed lampmussel. Fluoxetine EC50s ranged from 62 µg/L for juveniles (96 h) to 293 µg/L for glochidia (24 h). In adults, statistically significant increases were observed in foot protrusion at 0.37 and 29.3 µg/L fluoxetine and lure display rates at 29.3 µg/L; glochidia parturition was not significantly affected at any test concentration. Twenty-four hour exposure of glochidia to fluoxetine did not affect viability duration, but likelihood of metamorphosis to the juvenile stage significantly increased with 1 and 100 µg/L treatments. Our results demonstrated effects of fluoxetine to unionid mussels at concentrations less than previously reported and approaching concentrations measured in surface waters.

Acute effects of road salts and associated cyanide compounds on the early life stages of the unionid mussel Villosa iris.

The toxicity of cyanide to the early life stages of freshwater mussels (order Unionida) has remained unexplored. Cyanide is known to be acutely toxic to other aquatic organisms. Cyanide-containing compounds, such as sodium ferrocyanide and ferric ferrocyanide, are commonly added to road deicing salts as anticaking agents. The purpose of the present study was to assess the acute toxicity of three cyanide compounds (sodium cyanide, sodium ferrocyanide, and ferric ferrocyanide), two road salts containing cyanide anticaking agents (Morton and Cargill brands), a brine deicing solution (Liquidow brand), and a reference salt (sodium chloride) on glochidia (larvae) and juveniles of the freshwater mussel Villosa iris. Sodium ferrocyanide and ferric ferrocyanide were not acutely toxic to glochidia and juvenile mussels at concentrations up to 1,000 mg/L and 100 mg/L, respectively. Lowest observed effect concentrations (LOECs) for these two chemicals ranged from 10 to >1,000 mg/L. Sodium cyanide was acutely toxic to juvenile mussels, with a 96-h median effective concentration (EC50) of 1.10 mg/L, although glochidia tolerated concentrations up to 10 mg/L. The EC50s for sodium chloride, Liquidow brine, Morton road salt, and Cargill road salt were not significantly different for tests within the same life stage and test duration (range, 1.66-4.92 g/L). These results indicate that cyanide-containing anticaking agents do not exacerbate the toxicity of road salts, but that the use of road salts and brine solutions for deicing or dust control on roads may warrant further investigation.

Partial life-cycle and acute toxicity of perfluoroalkyl acids to freshwater mussels.

Freshwater mussels are among the most sensitive aquatic organisms to many contaminants and have complex life-cycles that include several distinct life stages with unique contaminant exposure pathways. Standard acute (24-96 h) and chronic (28 d) toxicity tests with free larva (glochidia) and juvenile mussels are effective at generating data on contaminant effects at two discrete life stages but do not incorporate effects on brooded glochidia. We developed a novel partial life-cycle assay that incorporates exposures to brooding adult female mussels and used this method in combination with acute toxicity tests to assess adverse effects of perfluoroctanesulfonic acid (PFOS) and perfluoroctanoic acid (PFOA) on freshwater mussels. Fatmucket (Lampsilis siliquoidea) were exposed to PFOS at two life stages: brooding glochidia (in marsupia) for 36 d and free glochidia in water for 24 h. In standard acute tests with glochidia (24-48 h exposures) and juveniles (48-96 h exposures) of fatmucket and black sandshell (Ligumia recta), glochidia were 8 to 25 times more sensitive than juveniles. Perfluoroctanesulfonic acid significantly reduced the duration of glochidia viability and reduced probability of metamorphosis at concentrations 3,000 times lower than the most sensitive acute endpoint (24-h EC50). The partial life-cycle test is adaptable to a variety of endpoints and research objectives and is useful for identifying adverse effects at contaminant concentrations below those required for an acute lethal response.

Thermal tolerance of juvenile freshwater mussels (Unionidae) under the added stress of copper.

Freshwater mussels fulfill an essential role in aquatic communities, but are also one of the most sensitive and rapidly declining faunal groups in North America. Rising water temperatures, caused by global climate change or industrial discharges, can further challenge impaired unionid communities, but thermal stress is almost certainly not the only stressor affecting freshwater mussels. Metals, such as copper (Cu), are a common source of toxicant exposure in aquatic environments. The toxic effects of Cu on the early life stages of freshwater mussels have been well studied, and freshwater mussels are more sensitive to Cu than most aquatic organisms. The purpose of the present study was to determine the effect of a sublethal copper concentration on the upper thermal tolerance of three species, Lampsilis siliquoidea, Potamilus alatus, and Ligumia recta, of juvenile freshwater mussels in 48- and 96-h tests. Thermal tolerance was determined over a range of experimental temperatures (20-42 degrees C) at three acclimation temperatures (17, 22, and 27 degrees C). Median lethal temperatures (LT50s) were calculated in the absence and presence of Cu, and at 48 h ranged from 34.6 to 44.4 degrees C (mean 37.7 degrees C) without Cu, and from 33.8 to 38.9 degrees C (mean 35.8 degrees C) with Cu. The LT50s at 96 h ranged from 32.5 to 35.6 degrees C (mean 34.5 degrees C) without Cu and from 33.0 to 35.4 degrees C (mean 34.2 degrees C) with Cu. Potamilus alatus had a significantly lower 48 h LT50 with Cu than without Cu at the 22 degrees C acclimation temperature; there were no other significant differences in LT50s attributed to Cu. Survival trends showed limited evidence of interactive effects between copper and temperature for all three species, suggesting the combined stress of elevated temperatures and copper exposure to freshwater mussels should be further explored.

Heart rate as a sublethal indicator of thermal stress in juvenile freshwater mussels.

Freshwater mussels (Unionoida) are one of the most sensitive and rapidly declining faunal groups in the world. Rising water temperatures, caused by industrial discharges, land development, or climate change can further challenge threatened unionid communities. The direct relationship between heart rate and temperature in ectotherms enables the use of heart rate as an indicator of whole-animal thermal stress. The purpose of this study was to assess the utility of heart rate as an indicator of thermal stress in freshwater mussels. Seven species of juvenile mussels (Lampsilis siliquoidea, Potamilus alatus, Ligumia recta, Ellipsaria lineolata, Megalonaias nervosa, Alasmidonta varicosa, and Villosa delumbis) were evaluated in response to a range of experimental temperatures (20-36 degrees C) at three acclimation temperatures (17, 22, and 27 degrees C). Heart rate was measured by direct visual observation through transparent mussel shells. The average heart rate for all 7 species at 20 degrees C was 55bpm, with a range from 38bpm (L. recta) to 65bpm (P. alatus). L. recta and V. delumbis exhibited significant changes in heart rate with increasing temperature at each of the three acclimation temperatures. The use of heart rate appears to be a suitable indicator of thermal stress in some unionid mussels.

Reducing lead exposure from drinking water: recent history and current status.

This article discusses the issue of lead contamination of drinking water, noting the various regulatory-driven measures that have been adopted in the U.S. since 1986 to address this public health issue. The article summarizes the literature on the dynamics of tap water lead contamination and discusses this widespread source of lead exposure in the context of the latest research evidence.

Artificial Christmas trees: how real are the lead exposure risks?

Exposure to lead has long been recognized as a major public health issue in the United States and other industrialized nations. The health risks associated with low lead levels mean that consumer products (such as those made from polyvinyl chloride [PVC] plastic, which often incorporates lead as a stabilizer) with even moderate lead exposure risks could be dangerous. The purpose of the experiments reported in this article was to test for lead exposure from artificial Christmas trees made of PVC, which are now present in an estimated 50 million U.S. households. The first phase of experimentation tested artificial Christmas trees in the laboratory for lead content in branches, lead transfer from hand contact, and lead dust levels under the tree. The second phase was based on a field-testing survey of households with artificial Christmas trees. Results from these experiments show that, while the average artificial Christmas tree does not present a significant exposure risk, in the worst-case scenarios a substantial health risk to young children is quite possible.