Tributyltin concentrations in sediments in the Coral Bay area at the Ningaloo MPA

No new data has been collected or collated, therefore data presented here has been carried over from last year.

Anti-fouling chemicals used on shipping and other marine structures (e.g. jetties and pylons) are another source of chemical contamination to marine waters (Environmental Protection Authority 1990). Tributyltin (TBT) compounds have been used as biocides incorporated in antifouling paints since the 1960s. TBT has been recorded in coastal waters since the 1980s (Fandry et al. 2006; Terlizzi et al. 2004; Whitney 1991; World Health Organization 1991). The leachates associated with these antifoulants are known to impact water quality condition, which in turn has deleterious effects on marine biota (Gibbs and Bryan 1994; Negri and Heyward 2001; World Health Organization 1990). In Australia, antifoulants containing tributyltin are not allowed to be used on vessels under 25 m in length, however the legacy of its use will be long lived as TBT is persistent in sediments which may be re-suspended due to natural and anthropogenic disturbances (Langston and Burt 2007; Maata and Koshy 2001).

In 1994 a survey undertaken by the then Department of Environmental Protection (Simpson and Field 1995) reported high TBT levels in the sediments of Coral Bay. Since then, there have been changes in the usage of TBT antifoulants and implementation of better boating practices in the bay. A small targeted survey undertaken by the Exmouth District with support from the Marine Science Branch, returned below detection limit concentrations of TBT at Mauds Landing, Inner Coral Bay and Moncks Head, indicating that TBT in sediments is no longer of concern and TBT antifoulants are now not considered an anthropogenic pressure on sediment health.

There has been no further TBT in sediment surveys.