Publication Summary

Sediments from the inner portion of the Squalicum Harbor Marina were analyzed for TBT in bulk sediment and sediment pore water.

TBT concentrations were lower than proposed regulatory limits for pore water.

The potential for TBT bioaccumulation was studied using Macoma clams exposed to the sediment under laboratory conditions. TBT concentrations in clams were lower than levels of concern from the scientific literature.

The number and variety of animals living in the sediments were reduced at sampling stations with higher TBT concentrations. However, this could be at least partly due to things related to TBT concentrations rather than the poisonous effects of this chemical acting alone.

The effect of TBT contamination on benthic invertebrate communities needs further investigation.

During 2005, sediments from the inner portion of the Squalicum Harbor Marina in Bellingham were analyzed for tributyltin (TBT) in bulk sediment and sediment pore water. The highest TBT concentrations occurred close to an area of the marina where bottom scraping and painting of boats has been conducted.

Regulatory limits for TBT concentrations in bulk sediment have not been established. However, TBT concentrations detected in this study were not higher than proposed regulatory limits for TBT concentrations in pore water.

Biological effects of the TBT contamination were examined. The potential for TBT bioaccumulation was studied using Macoma clams exposed to the sediment under controlled laboratory conditions. TBT concentrations in the clam tissues did not exceed levels of concern found in the scientific literature.

The abundance and diversity of benthic marine invertebrates (e.g., clams, worms) at sediment sampling locations were evaluated. Invertebrate abundance and diversity were reduced at sampling stations with higher TBT concentrations in sediment (0.12-0.26 mg/kg dw, and 1.16 mg/kg in one subsample) compared to stations with lower concentrations (0.04 mg/kg or less). However, there may be other factors correlated with the TBT concentrations that affect these invertebrate communities. These results indicate a need to further investigate the effects of TBT contamination in sediments on benthic invertebrate communities.

Link to EIM data for User Study ID NBLA0003