Problems of acid-base balance in rapidly changing intertidal environments

Abstract

SYNOPSIS. Many physical factors vary widely and rapidly in residual water bodies left on the shore by the receding tide. Whereas variations of temperature and salinity depend on climatic conditions, the changes of oxygen and carbon dioxide are mainly governed by biological activities. Typically, such waters become hypoxic-hypercapnic at night and hyperoxic-hypocapnic during the day at low tide. According to findings in single-factor laboratory experiments, all these variables can potentially disturb acid-base balance in tidepool animals. However, the whole response of the organism to the complex natural situation can hardly be predicted and must be approached in the field or in simulated environments. Measurements on crabs Carcinus maenas acclimated to an artificial tidepool show only moderate hemolymph acid-base changes, due mainly to counteracting influences of the concerted variations of water oxygen and carbon dioxide. The pH-temperature slope for these crabs was -0.016 pH unit°C-1 in agreement with an imidazole alphastat pattern of acid-base regulation. © 1988 by the American Society of Zoologists.