PHOSPHORUS-METABOLISM MONITORED BY P-31 NMR IN JUVENILE SEA SCALLOP (PLACOPECTEN-MAGELLANICUS) OVERWINTERING IN PEARL NETS AT A NOVA-SCOTIAN AQUACULTURE SITE

P-31 Nuclear magnetic resonance (NMR) spectroscopy has been used to examine in vivo phosphorus metabolism in juvenile sea scallop (Placopecten magellanicus) from an aquaculture site in Nova Scotia. NMR-visible arginine phosphate (Arg P) concentrations declined from summer to winter whereas inorganic phosphate (P-i) levels increased and those of adenosine triphosphate (ATP) remained relatively constant. Our results indicate that, in the scallop that uses the phosphagen Arg P to replenish ATP, the ratio of Arg P to P-i is a better indicator of energetic status than is the ratio of adenylate concentrations known as adenylate energy charge. Scallops collected in fall and winter, when exposed to hypoxic conditions, showed pronounced decreases in Arg P associated with increases in P-i and decreases in ATP levels whereas these remained relatively unchanged in scallops collected in summer. Scallops maintained under simulated winter conditions showed lower levels of Arg P associated with poor nutrition, and a response to hypoxia similar to field scallops. The marked seasonality in concentrations of phosphorus metabolites emphasizes their potential importance as useful biomarkers in environmental stress assessment and the optimization of hatchery and grow-out conditions.