Predicting toxicity in marine sediment in Taranto Gulf (Ionian Sea, Southern Italy) using Sediment Quality Guidelines and a battery bioassay

Abstract

The goal of this study was to assess coastal marine pollution in the Mar Piccolo and Taranto Gulf (Ionian Sea, Southern Italy) by combining chemical and toxicological data in order to compare and integrate both approaches. Pollutants levels, traditionally, have limited ability to predict adverse effects on living resources. Moreover, in order to provide information on the ecological impact of sediment contamination on aquatic biota Numerical Sediment Quality Guidelines (SQGs) and sediment toxicity bioassays were carefully recommended. In this study ERL (effect range low)/ERM (effect range medium value) and TEL (threshold effect level)/PEL (probable effect level) guidelines have been used. Bioassays were performed with two species of amphipods Gammarus aequicauda and Corophium insidiosum, one species of isopod Idotea baltica and bivalve Mytilus galloprovincialis larvae. The TEL/PEL analysis suggested that, especially for stations 1 and 2, sediments in Mar Piccolo should contain acutely toxic concentrations of metals. In particular Hg content, in station 1, was about 17 times PEL value. 96 h LC₅₀ and 48 h EC₅₀ values were estimated for cadmium, copper and mercury in these species using the static acute toxicity test. M. galloprovincialis larvae was more sensitive than other species to all the reference toxicants tested (EC₅₀ determined for cadmium copper and mercury were of 0.59, 0.11 and 0.01 mg/l respectively). Significant differences in sensitivity of species tested to all reference toxicants (ANOVA p < 0.001) were recorded. Bioassays with these species allowed to estimated sediment toxicity from the different studied sites. On the basis of results obtained a good agreement was reported between chemical data and response of the biological endpoints tested.