Nitrogen excretion and changes in blood components during emersion of the subtidal spider crab Maia squinado (L.)

Survival ability of Maia squinado to emersion and subsequent reimmersion wa s determined in winter and summer conditions. Male spider crabs were less t olerant of emersion than females. Emersion (up to 24 h in summer and to 48 h in winter) induced a marked reduction of nitrogen excretion, especially a mmonia excretion. Increase in blood ammonia content was rapid and very high in summer (1750 mu mol l(-1)), but non-lethal levels. Estimation of the bo dy ammonia overload showed that only 30% of unexcreted ammonia accumulated in blood. The ammonia release at reimmersion indicated that ammonia also ac cumulated in other body compartments. Increase in blood urate content, whic h indirectly reduces ammonia production, was similar at both seasons. Emers ed M. squinado was rapidly resorting to anaerobic metabolism, especially in summer when its blood haemocyanin content is low. A strong hyperglycemia w as developed in the first 12 h of emersion at both seasons. Mortality occur ring beyond 24 h of reimmersion, when the body ammonia overload is cancelle d and the recovery of most of blood components is achieved, remains unexpla ined. (C) 2000 Elsevier Science Inc. All rights reserved.