Behavioural endpoints in Ruditapes philippinarum exposed to contaminated sediments.

Sediment pollution has the potential to affect reburrowing behavior in infaunal organisms, thus the observed changes would be useful deployed in a toxicity bioassay for contaminated sediments. In this study the burrowing behavior of Ruditapes philippinarum has been evaluated exposing animals both to Cu-spiked sediments (100, 300 and 1000 ?g Cu/g w.w.) and to natural sediments collected at differently impacted transitional and coastal sites. Exposure time was set at 48 h and changes in the re-burrowing behavior were evaluated through two different endpoints: RT50, i.e. time required for 50% of the organisms to burrow, and percentage of burrowed organisms at the end of exposure time. To this end, a specific software for continuous observations and quantitative analysis of the reburrowing rate has been developed. Results evidenced that both end-points were significantly affected by the micro-contaminant level in either spiked or natural sediments, confirming the suitability of reburrowing changes in R. philippinarum to be used as sensitive endpoints in whole-sediment acute toxicity bioassay.