Accumulation of organotins in wharf roach (Ligia exotica Roux) and its ability to serve as a biomonitoring species for coastal pollution

In this study, we measured the accumulation of tributyltin (TBT) in wharf roach (Ligia exotica Roux) and examined the species' ability to be used for TBT biomonitoring in coastal environments. In an exposure test, wharf roach were exposed to TBT via diet for 2 d. TBT was accumulated in wharf roach, and its metabolite dibutyltin was detected. The concentrations of these compounds gradually decreased during the depuration period, but they were still detected 12 d after exposure ceased (TBT 290±140 ng/g; dibutyltin 1280±430 ng/g). The biological half-life of TBT in wharf roach was estimated to be about 4 d. In a field study conducted in 2011-2012, wharf roach were collected from 15 coastal sites in Japan and 3 sites in Manado, Indonesia. TBT was detected in both Japanese and Indonesian samples. The highest concentration of TBT was found in wharf roach collected at Bitung ferry port, Manado (57.9±16.5 ng/g), which is close to a shipyard, and the highest concentration at a Japanese site was 12.3±6.2 ng/g. Thus, we were able to detect organotins in the coastal environments by testing wharf roach, suggesting that L. exotica might serve as a good bioindicator for monitoring organotin pollution.