1) The effects of hypo- and hyper-osmotic media on ammonia efflux rates and haemolymph constituent levels in the spiny lobster, Panulirus interruptus.

During post-harvest treatments of live spiny lobsters, Panulirus interruptus, in the Baja California fishery, the animals may be subjected for some hours to periods in hypo-osmotic (freswater ice cooling) or hyper-osmotic (evaporation) media. The variability of haemolymph levels of ammonia, protein, haemocyanin, lactate, and glucose and the weight-specific ammonia efflux rates of spiny lobsters were examined in laboratory simulation of 4 h periods to such commercial treatments.

Compared with control group animals (38psu), those in hyper-osmotic (41, 45 and 50 psu) media showed depressed ammonia efflux rates but non-significant changes to the other variables measured. The groups in hypo-osmotic (25, 30 and 35 psu) media showed a trend of elevated haemocyanin and blood ammonia levels and ammonia efflux rates but with little change to the other variables measured.

Mortalities were nil during the experiment and all animals recovered after treatments, suggesting that this osmoconforming species is able to cope with such changes using strategies which include manipulation of their ammonia production and excretion rates to produce a regulated blood ammonia level appropiate to their external osmotic conditions.