High sensitivity of embryo-larval stage of the Mediterranean mussel, Mytilus galloprovincialis to metal pollution in combination with temperature increase

The present work aimed to assess the effects of two widespread metallic pollutants, copper and silver, along with environmentally-realistic temperature increases, on embryo-larval development of the Mediterranean mussel Mytilus galloprovincialis. First, mussel embryos upon fertilization were exposed for 48 h to increasing concentrations of Cu (0.5-500 mu g/L) and Ag (0.1-100 mu g/L) at different temperatures (18, 20, 22 or 24 degrees C) in order to characterize toxicity of each toxicant at the different tested temperatures. Increasing concentrations of a Cu-Ag mixture were then tested in order to assess the mixture effect at different temperatures (18, 20 or 22 degrees C). Embryotoxicity was measured after 48 h of exposure (D-larvae stage) considering both the percentage of abnormalities and developmental arrest in D-larvae. The results suggest that the optimum temperature for mussel larvae development is 18 degrees C (12.65 +/- 1.6% malformations) and beyond 20 degrees C a steep increase of abnormal larvae was observed up to 100% at 24 degrees C. Ag was more toxic than Cu with a 50% effective concentration (EC50) at 18 C of 6.58 mu g/L and 17.6 mu g/L, respectively. Temperature increased the toxicity of both metals as proved with the EC50 at 20 degrees C at 3.86 mu g/L and 16.28 mu g/L for Ag and Cu respectively. Toxic unit calculation suggests additive effects of Cu and Ag in mixture at 18 and 20 degrees C. These results highlight a possible impairment of M. galloprovincialis reproduction in the Mediterranean Sea in relation to increase of both pollutants and water temperature due to global warming. (C) 2016 Elsevier Ltd. All rights reserved.