Environmental changes, such as temperature, pH, salinity and oxygenation, affect the physiological state of marine organisms. However many species are able to maintain their homeostatic conditions in spite of environmental variations. In particular, compensation mechanisms against oxygen depletion have been studied in marine animals due to the high variability of oxygen levels in the aquatic environments. The aim of this work is to study the physiological responses to emersion and other stressful environmental conditions in the valuable commercial species Squilla mantis, in order to optimize the use of this marine resource. Laboratory and field-based studies were carried out to explore the effects of emersion and thermal shocks. Physiological stress upon emersion and recovery after re-immersion was assessed by analysing hemolymph metabolites (L-Lactate, D-glucose, ammonia, H⁺) as well as glycogen concentration in tissues. The oxygen transport protein, hemocyanin, plays an important role in increasing the uptake of oxygen under hypoxic conditions. As the L-lactate levels increase above the resting level (from 1 mM to 14 mM), the oxygen affinity of the protein is markedly increased (d log p50/ d log [L-lactate] of about -0.58). Also the Bohr-effect is quite pronounced with a Bohr coefficient of -0.32 in the pH range between 6.5 and 7.6 and a value of -1.16 between pH 7.6 and pH 8.0.

This project was supported by Regione Veneto (Project CLODIA).