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Abstract
The red swamp crayfish (Procambarus clarkii) is an opportunistic omnivore, feeding on algae, detritus, and animal matter. The contribution of each of these to the diet varies with availability as well as age and sex of the crayfish. Few studies have addressed how sex and age affect Hg uptake and elimination in crayfish, or examined physiological and behavioral changes due to chronic dietary Hg exposure. We exposed juvenile crayfish (n=72) of known age and sex to diets containing relatively high and low concentrations of methylmercury (MMHg) using a 2x2x3 randomized block design. The low Hg diet averaged 9 ppb Hg fresh weight (80% MMHg) while the high Hg diet averaged 278 ppb Hg fresh weight (98% MMHg), both environmentallyrealistic concentrations. Sub-lethal effects after 142 days of chronic exposure included alterations in behavior and growth, with severity varying based on sex and age. In nature, these effects could reduce crayfish survival.