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Providing evidence to improve practice

Action: Restrict the use of tributyltin or other toxic antifouling coatings Subtidal Benthic Invertebrate Conservation

Key messages

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  • Four studies examined the effects of restricting the use of tributyltin as an antifouling coating on subtidal benthic invertebrate populations. One study was located in the English Channel (UK), two in the River Crouch estuary (UK), and one in Otsuchi Bay (Japan).

 

COMMUNITY RESPONSE (2 STUDIES)

  • Overall community composition (1 study): One replicated, before-and-after study in the River Crouch estuary found that after restricting the use of tributyltin, invertebrate community composition changed, but that changes varied with locations.
  • Overall richness/diversity (1 study): One replicated, before-and-after study in the River Crouch estuary found that after restricting the use of tributyltin, overall invertebrate species richness and diversity increased.

POPULATION RESPONSE (2 STUDIES)

  • Molluscs condition (1 study): One replicated, before-and-after study in the English Channel found that after restricting the use of tributyltin, there was a decrease in its concentration in dogwhelks and the penis length of female dogwhelks.
  • Crustacean condition (1 study): One study in Otsuchi Bay found that after restricting the use of tributyltin its concentration decreased in skeleton shrimps.

Supporting evidence from individual studies

1 

A replicated, before-and-after study in 1985–1993 of seven soft seabed sites in the southwest English Channel, UK (Bryan et al. 1993) found that restricting the use of tributyltin (TBT) resulted in decreases in tributyltin concentrations in netted dogwhelks Nassarius reticulatus and in the penis length of female dogwhelks, at five of the sites five years after the restriction. In these five sites, TBT concentrations in dogwhelks were lower five years after the restriction (8–68 ng/g; range of averages across sites) compared to before (123–390 ng/g). The penis length of females was lower five years after the restriction (3–5 mm) compared to before (5–7 mm). There were no changes in the penis length of males over time (data not presented). There were no statistical trends over time at the other two sites. The use of antifouling ship paints containing TBT was restricted in 1987 in the UK. Approximately every six months between 1985 and 1993, at least 30–40 dogwhelks were collected using a dredge or by diving at each of seven sites at 9 m depth. The TBT concentration of each individual (after being dried) and their penis length were measured as affected female marine invertebrates develop male genitals.

2 

A replicated, before-and-after study in 1987–1992 of seven coarse seabed sites along the River Crouch estuary, southeast England, UK (Rees et al. 1999– same experimental set-up as Waldock et al. 1999) found that after restricting the use of tributyltin (TBT), overall epifaunal invertebrate (living on the seabed) community composition changed over five years, but the direction of change varied with site location. In four upper-estuary sites, overall invertebrate community composition changed over the five years, in a similar direction. In three lower-estuary sites, overall invertebrate community composition changed over the five years, without displaying a directional trend. Data were reported as graphical analyses, but not statistically tested. The use of antifouling ship paints containing TBT was restricted in 1987 in the UK. Annually in 1987–1989 and 1992, epifaunal invertebrates were surveyed at seven sites along a 23 km axis of the river. One to three sediment samples/year/site were collected using a trawl towed over 250 m, epifaunal invertebrates (> 5 mm) were identified and counted.

3 

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.

4 

A study in 1994–2001 of one soft seabed sites in Otsuchi Bay, northern Japan (Takeuchi et al. 2004) found that, between four and 11 years after restricting its use, tributyltin (TBT) was still present in four species of Caprella skeleton shrimps, but concentrations were declining.  Tributyltin concentrations significantly declined in Caprella danilevskii from 59 ng/g four years after restriction to 3.3 ng/g 11 years after restriction, in Caprella subinermis from 57 ng/g in four years after restriction to 29 ng/g 10 years after restriction, in Caprella penantis from 66 ng/g five years after restriction to 4 ng/g 11 years after restriction, and in Caprella verrucosa from 32 ng/g seven years after restriction to 10 ng/g nine years after restriction. The use of antifouling ship paints containing TBT was restricted in 1990 in Japan. Annually in 1994–2001 an unspecified number of shrimps living on the macroalgae Sargassum were collected at one site (3 m depth). They were then identified as one of four Caprella species, and TBT concentrations measured for each species. Not all species were collected each year.

Referenced papers

Please cite as:

Lemasson, A.J., Pettit, L.R., Smith, R.K., and Sutherland, W.J. (2019) Subtidal Benthic Invertebrate Conservation: Global Evidence for the Effects of Interventions. Synopses of Conservation Evidence Series. University of Cambridge, Cambridge, UK.