Response of haemolymph oxygen affinity to simultaneous salinity and oxygen stress in the intertidal prawn, Palaemon elegans (rathke)

Abstract

1. 1. Specimens of the intertidal prawn Palaemon elegans were acclimated to nine different combinations of salinity and oxygen availability. The conditions ranged from hyposaline (15%o) to hypersaline (40%o) and from hypoxia (50 Torr) to hyperoxia (500 Torr). 2. 2. P. elegans was able to regulate haemolymph Ca 2+, Mg 2+ and Cl −, independent of the oxygen tension of the water. 3. 3. The oxygen affinity and pH sensitivity of oxygen binding by the haemocyanin both increased when the acclimation salinity was highest at 40%, but were unaffected by the acclimation oxygen tension. 4. 4. The dependence of oxygen affinity on the concentration of l-lactate was relatively low (Alog P 50/Alog[lac −] ranged from −0.10 to −0.23) but was independent of the acclimation salinity and oxygen tension. 5. 5. It was concluded that acclimation to the conditions used influenced oxygen affinity primarily via altered concentrations of Ca 2+ and Mg 2+ in the haemolymph.