OXYGEN-TRANSPORT BY THE HEMOCYANIN OF THE PROTOBRANCH MOLLUSK SOLEMYA-REIDI

Oxygen transport by the hemocyanin of the protobranch mollusc Solemya reidi Bernard was studied in native hemolymph samples. Clams were coll ected from two different reducing environments, beneath log booms in A lberni Inlet, British Columbia, Canada, and from the sewage effulent i n Santa Monica Bay, California, USA. The hemocyanin concentration in a pooled hemolymph sample (n = 10 individuals) was 33.5 mg ml(-1). The mean hemolymph pH of five Alberni clams maintained for 3 wk in mud was 7.96 +/- 0.06. No significant variation in hemocyanin oxygen-affinity or cooperativity was found for hemocyanin ill whole hemolymph samples from these five individually studied clams. There was a significant d ifference only at 15 degrees C in the oxygen affinity of hemocyanin in pooled whole hemolymph samples from S. reidi collected from Alberni I nlet compared with clams collected from Santa Monica Bay. Little effec t of temperature on hemocyanin oxygen-affinity was found for temperatu res below 20 degrees C; above 20 degrees C, the oxygen affinity was re duced for clams from both sites. Temperature and pH had no apparent af fect on hemocyanin cooperativity. Moderate Bohr shifts were found at a ll temperatures examined. The presence of physiologically relevant con centrations of thiosulphate in hemocyanin samples resulted in a decrea se in hemocyanin oxygen-affinity, opposite to the effect on hemocyanin found for the hydrothermal vent crab Bythograea thermydron, but thios ulphate had no effect on hemocyanin cooperativity.