Short-term physiological response of the Pacific oyster, Crassostrea gigas, on exposure to varying levels of polycyclic aromatic hydrocarbon

Abstract

In the present study, we investigate the short-term adaptive physiological strategies to polycyclic aromatic hydrocarbon (PAH) of Pacific oysters, Crassostrea gigas, by exposing the oysters to varying levels of PAH (0, 50, 100 and 200 mu g L-1) for 7 days with a 3-day acclimation period under laboratory conditions. The filtration rate (FR) and respiration rate (R) increased significantly at 50 mu g L-1 PAH and decreased at 100 and 200 mu g L-1 compared with the control. The absorption efficiency (Abs. eff.) was significantly impaired at 200 mu g L-1 PAH. Ammonia excretion (E) increased with increasing PAH levels, with a significant elevation at 200 mu g L-1. Although a significantly elevated FR was observed, oysters exposed to 50 mu g L-1 PAH showed scope for growth (SFG) similar to the control. This indicates that even at nominal levels, PAH contamination is a possible cause of reduced oyster production because of increased food demand. The oysters exposed to 200 mu g L-1 PAH showed negative SFG values, which could be a possible cause of growth stagnation or even mortality when the exposure is chronic.