Tributyltin (TBT) has been extensively used over the last decade as a biocide in anti-fouling paints. Although TBT is extremely effective in preventing the settlement of plants and animals on ship hulls, it is now clear that other marine organisms besides those targeted are significantly affected by the TBT leaching from anti-fouling paints.
In estuaries and marinas in the UK, where large numbers of pleasure craft are moored, lvel of TBT during 1986 ranged from less than 1 nanogram (ng)1−1 in the winter up to 1500ng1−1 in the summer (ref 1). Sensitivity to TBT varies among aquatic species, with gastropods and bivalves being the most susceptible (20–140 ng 1−1) followed by crustaceans (90–140 ng 1−1), algae (100–250ng 1−1) and fish (200 ng1−1) for reviews see refs 1–3)
Most TBT toxicity tests have been carried out on single species in the laboratory, and although these tests provide useful information, they can be criticized because they may not be relevant to the undoubtedly more complex situation in the wild. Field trials, such as the transfer of animals between clean and polluted areas, can also be criticized for their lack of controlled conditions. This chapter reviews laboratory and field data and investigates evidence of the ecological effects of TBT in a microcosm toxicity study involving a range species in a muddy-sand substrate (refs 4, 5) such microcosm studies are mostly under laboratory control, but exhibit much of the ecological complexity found in the wild.
The microcosm study confirms the high sensitivity of molluscs to TBT and reveals the significant ecological damage which can accrue from the use of TBT-based anti-fouling paints on pleasure craft in enclosed waters.
Walsh et al (ref 6) and Beaumont and Newman (ref 7) have demonstrated that 100–300 ng 1−1 TBT reduced the growth of certain microalgal species. The most sensitive so far test is the diatom Skeletonema coastatum, which shows no growth at all at 100 ng1−1 Preliminary trials investigating respiration and photosynthesis in the microalga Pavlova lutheri and the macroalga Ulva lactuca (ref 4) indicate that 100ng 1−1TBT can cause a significant increase in algal respiration. This may be due to damage caused to the mitochondria since there is evidence of mitochondrial damage due to TBT in animals (ref 8). The effects of TBT on photosynthesis could not be resolved in these trials owing to interference by the acetic acid used as a carrier to introduce TBT into solution.
Microalgae are primary producers in the aquatic environment, and therefore reduced growth or mortality of microalgae could have far-reaching effects on life at higher levels in the food chain.
A number of crustaceans have been tested for the effects of TBT Levels of between 200 and 1000ng 1−1 significantly reduce growth of larvae of Homarus americanus, the American lobster (ref 9), and juveniles of the mysid shrimp Acanthomysis sculpta (ref 10) Effects on reproduction were also noted in adult female A sculpta, and behavioural effects have been demonstrated in the freshwater flea.