Influence of salinity on fertilization and larval development toxicity tests with two species of sea urchin

Sea urchin embryo-larval development (ELD) and fertilization tests have been widely used in ecotoxicity studies and are included in regulatory frameworks. Biological processes occur naturally within a range of salinity that depends on the species considered. In an attempt to determine the optimum range of salinity, ELD and fertilization bioassays were performed at different salinities (15-40.5 parts per thousand.) with two species of Atlantic sea urchin: Arbacia lixula and Paracentrorus lividus. In the ELD assay, the optimum range of salinity was wider for A. lixula (29-35.5 parts per thousand) than for P. lividus (29-33 parts per thousand). In the fertilization assay with P. lividus as a bioindicator species, the highest percentage of fertilization (90%) was obtained at salinities of between 29 and 33 parts per thousand. More research on A. lixula is required, since the fertilization success was below 60%. The results of the present study demonstrate that salinity may be a confounding factor in interpreting ELD test results. (C) 2011 Elsevier Ltd. All rights reserved.