Meeting Abstract
P1.154 Sunday, Jan. 4 Responses of Blue Crabs to Hypoxia in Fresh Water MARTIN, James, T.*; DEFUR, Peter, L.; Virginia Commonwealth Univ; Virginia Commonwealth Univ pldefur@vcu.edu
Previous work demonstrated that blue crabs (Callinectes sapidus) in saline waters respond to long term hypoxia by increasing hemocyanin concentration and oxygen transport properties. Additionally, researchers reported that under field conditions and lab simulations, hypoxia is accompanied by hypercapnia and low pH, affecting hemolymph pH. The present research examined responses of blue crabs to long term hypercapnic hypoxia in freshwater at 23C. Hypoxic conditions (50-60 mmHg O2) were induced by allowing the crabs to consume oxygen supply, resulting in a hypercapnic induced decrease in pH from 7.88 to 7.18. Post-branchial hemolymph oxygen and pH were measured in normoxia, after 24 hours of hypoxia and several days later. Within 24 hours, postbranchial hemolymph oxygen declined 46% to 79%, but post-branchial pH changes varied from -0.167 to +0.171 The initial responses to hypoxia demonstrates that blue crabs prevent extreme postbranchial hemolymph pH changes under acidic stress as well as maintain postbranchial oxygen tension. Despite the variation in postbranchial hemolymph among individual crabs, 86% mortality occurred during three days of hypoxia. The high mortality rate suggests the blue crabs are not able to survive the multiple stress of hypoxia/hypercapnia along with the stress of living in freshwater. It is not clear if the elevated mortality results from a failure of oxygen transport, acid-base balance or ion regulation. Supported by a Rice Center Graduate Student support grant to JTM.
