A novel approach to measuring chlorophyll uptake by cultivated oysters

Abstract

Chlorophyll uptake was monitored in caged oysters (Crassostrea virginica) using in situ fluorometers. Cages were suspended in a dynamic water column environment and allowed to orient freely with the current. Current velocity inside the cages ranged from 1.8 to 11.7 cm s−1. No evidence of feeding stress was found at peak current velocities, a result compatible with the ongoing development of suspended-culture practices. In summer, chlorophyll uptake was significantly (P < 0.05) and positively correlated with current velocity (r2 = 0.29–0.39), chlorophyll concentration (r2 = 0.43–0.51), and chlorophyll influx (r2 = 0.59–0.61). The positive nature of these relationships suggests that food supply was limiting in the suspended cages. In autumn, increased chlorophyll uptake was coupled to a developing algae bloom (rising influx); however, uptake fell before the bloom had fully developed.