POWELL, M.L.*; WATTS, S.A.: Survivor: The Energetics of Crayfish in Burrows

Procambarus clarkii (PC) and P. zonangulus (PZ) share overlapping ranges in the southeastern United States. Within this shared range the success of each species varies, possibly related to the ability to survive environmental challenges and extended periods of nutrient deprivation during the summer when both species retreat to burrows. Metabolic rate, proximate composition and energy content were determined for adult male crayfish during a five-month starvation period. The pattern and source of nutrients utilized during starvation varied between species. In PZ 75 % of the tail muscle and 30 % of the hepatopancreas was mobilized during the starvation period, compared to 60 % of both the tail muscle and hepatopancreas in PC. Although a greater percentage of the dry tissue was mobilized from the tail and hepatopancreas of both species, over 50 % of the total dry material was mobilized from the remaining carcass. Nutrient utilization in both species was tissue-specific; the hepatopancreas mobilized a greater percentage of lipid, and tail muscle a greater percentage of protein. PC mobilized almost twice as much energy as PZ, but from different tissues. PC mobilized 8 % of the energy from the hepatopancreas, 14 % from the tail and 78 % from the carcass. PZ mobilized 14 % of the energy from the hepatopancreas, 59 % from the tail and only 27 % from the carcass. Survivorship was 45 % for PC and 71 % of PZ. These different responses to nutrient deprivation may partially explain the observed changes in species composition in ponds.