Surveys of the benthic infauna of the Crouch Estuary (UK) in relation to TBT contamination.

Published source details Waldock R., Rees H.L., Matthiessen P. & Pendle M.A. (1999) Surveys of the benthic infauna of the Crouch Estuary (UK) in relation to TBT contamination.. Journal of the Marine Biological Association of the United Kingdom, 79, 225-232.
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This study is summarised as evidence for the following.

	Action	Category
	Restrict the use of tributyltin or other toxic antifouling coatings Action Link

Restrict the use of tributyltin or other toxic antifouling coatings

A replicated, before-and-after study in 1987–1991 of five soft seabed sites along the River Crouch estuary, southeast England, UK (Waldock et al. 1999– same experimental set-up as Rees et al. 1999) found that after restricting the use of tributyltin (TBT), infaunal invertebrate (living inside the seabed) species richness increased at all sites and diversity increased at sites located in the upper-estuary over four years. Data were not statistically tested. Species richness increased from 37 species before restriction to 63 four years after. Upper-estuary sites showed the greatest increases from 5–7 to 19–26 species, while the lower-estuary sites varied from 9–12 species before to 15–22 after. Before restriction, species diversity (reported as a diversity index) was higher at lower-estuary sites than upper-estuary sites. After restriction, diversity remained similar at lower-estuary sites but increased at upper-estuary sites so that they reached similar values to the lower estuary sites. TBT concentrations in sediments, although higher in the upper estuary than the lower estuary, decreased over time at all sites. The use of antifouling ship paints containing TBT was restricted in 1987 in the UK. Annually in 1987–1988 and 1990–1991, infaunal invertebrates (> 5 mm) were surveyed at five sites along the length of the estuary. Four sediment samples/year/site were collected using a grab, and invertebrates identified and counted.

(Summarised by: Anaëlle Lemasson)