Latent effects of hypoxia on the gastropod Crepidula onyx

Despite the importance of latent effects in marine invertebrates, no study has considered how larval exposure to hypoxia may have lasting impacts on the individual in later life history stages. In this study, we exposed larvae of the gastropod Crepidula onyx to 2, 3, and 6 mg O₂ l^-1, measured the larval size and total lipid content, transplanted the newly settled individuals to the field, and finally, determined the growth rate, dry weight, and filtration rate of the juveniles after 2 wk in the field. The experiments were conducted separately at low and high larval food concentrations. Under the low food concentration, both hypoxic treatments increased the time needed for the larvae to be competent to metamorphose. When they did, however, they had a size and total lipid content similar to the control larvae. The latent effects of early hypoxia exposure on juvenile growth were evident. The juvenile growth rate was reduced by ca. 14 and 10% in the 2 and 3 mg O₂ l ^-1 treatments, respectively. The mean dry weight and filtration rate were also significantly reduced in the hypoxic treatments. However, there was no discernible effect on larvae or juveniles when the food concentration during the larval stage was doubled, suggesting that the latent effects of hypoxia can be offset by larval access to high algal concentration. This study suggests that periodic hypoxic events and the resulting exposure of organisms to hypoxia during their early development may have effects that persist across the life history.