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Tin Tabulation

Levels of tin in sea water and ocean sediments have been occupying the time of post-graduates at Auckland University. Tributyltin is an effective active ingredient in marine paints, but has also been found to have disturbing effects on sea creatures.

Carol Stewart has seen some drastic modifications in the creatures she has studied, with oysters laying down enough shell to become completely round. Other marine creatures have become sterile, or even changed sex as a result of exposure to tin.

Stewart is monitoring tin levels near marinas and commercial fishing grounds. Deformed oysters can be found in some places up to 10 kilometres away, and tin deposits in sediments are detectable even after 10 years. Intertidal molluscs can be affected by concentrations lower than can be physically detected, with obvious implications for commercial aquaculture.