Effects of cadmium on the development and swimming behavior of barnacle larvae Balanus amphitrite Darwin

The lethal and sublethal effects of cadmium on stage II nauplii of the barnacle Balanus amphitrite Darwin were investigated. The developmental periods of the 6 larval and 1 cyprid stages were determined. For the stage II larvae, the 24-hour LC50 value for cadmium was 1.36 mgL-1. For an exposure period of 72 hours, increased levels of cadmium resulted in a reduction in the moulting success of stage II larvae, and the No observable effect concentration (NOEC) and lowest observable effect concentration (LOEC) were 0.20 and 0.25 mgL-1, respectively. Over 90 of the stage II larvae failed to develop into stage III larvae when the stage II larvae were exposed to 0.30 mgL-1 or higher levels of cadmium for 72 hours. The curvilinear velocities (VCL) and straight-line velocities (VSL) of the stage II nauplii in the control were 0.7 to 1.1 and 0.2 to 0.4 mm s-1, respectively. An exposure duration of 24 hour to 1.00 mgL-1 cadmium or higher caused a significant decrease in both VSL and VCL. For a longer exposure period of 48 hours, the LOEC was 0.80 mgL-1 cadmium. These findings suggest that the moulting success and swimming velocities of barnacle larvae, particularly stage II nauplii, could be useful endpoints for ecotoxicological assessments due to the reasonably high sensitivities and relatively short exposure durations. (C) 2000 by John Wiley and Sons.link_to_subscribed_fulltex