MP9 Metals and Bioaccumulation
Monday, 14 November 2005: 8:00 AM - 5:30 PM in Exhibit Hall

(JAG-1117-833883) Influence of temperature on dietary accumulation and toxic effects of methylmercury in red swamp crayfish Procambarus clarkii.

Jagoe, W¹, Jagoe, C¹, Brant, H¹, ¹ University of Georgia, Savannah River Ecology Lab, Aiken, SC, USA

ABSTRACT- Global warming may increase temperatures in lakes, streams and wetlands. Metabolism and food consumption increase with temperature in poikilothermic animals, so exposure to contaminants in the diet should also increase with temperature. Mercury is released into the atmosphere by industry and fossil fuel combustion, deposited to soils, wetlands and waters and methylated in these environments. Crayfish are poikilothermic omnivores that live in wetland environments where they can accumulate methylmercury from their foods. If metabolism and feeding increase with environmental temperature, mercury content in tissues might also increase. Methylmercury causes disorientation, and loss of sensory perception and coordination. Such neurotoxic effects could influence abilities to find food or shelter, defend territories, find mates, and avoid predators. These effects might increase at higher temperatures, if more methylmercury is accumulated from the diet. Procambarus clarkii (n=96) were held at either 15 or 20 C and fed diets of fish filets containing high or low (< 0.05 and > 1 mg/kg wet weight) methylmercury concentrations. Tissue mercury concentrations and ecologically-relevant behaviors (foraging, ability to find shelter and food detection) were measured after one, two and three months of exposure. Crayfish fed the high mercury diet accumulated significantly more mercury than those fed the reference diet. Crayfish consumed significantly more food at the higher temperature and accumulated about twice as much mercury in muscle as those fed the same diet at the lower temperature. Muscle mercury concentrations were 3 to 10 times higher than carapace concentrations. Our data support the idea that global climate change could increase accumulation of some pollutants in poikilotherms. Differences in behavior among treatments were not statistically significant. Our hypotheses about effects of mercury on behavior cannot be rejected at this time, although longer exposure could result in greater mercury accumulation and more marked behavioral differences.

Key words: mercury, climate change, behavior, crayfish