The Effects of Tributyltin on Dogwhelks (Nucella Lapillus) From Scottish Coastal Waters

Abstract

The common dogwhelk (Nucella lapillus) is a dioecious species. However, on exposure to low concentrations (<1 ng I-1, Gibbs et al., 1987) of tributyltin (TBT) females develop certain male sexual characteristics, notably a penis and vas deferens. This phenomenon, first reported by Blaber (1970) in dogwhelks from the Plymouth area, and later termed 'imposex' (Smith, 1981), is now recognised as the most sensitive and straightforward way to identify contamination of coastal areas by TBT. The degree of imposex may be readily quantified as the relative penis size index (RPSI), which expresses the relative bulk of the penes in females and males from a given sample. It is calculated as (mean cubed female penis length/the mean cubed male penis length) x 100% (Gibbs et al., 1987). Gibbs et al. (1987) have examined the development of imposex in greater detail, and have divided the process into six stages (known as the vas deferens sequence, or VDS) based upon the degree of development of the vas deferens and penis in the female animal. This classification enables an assessment to be made of the reproductive ability of an animal. Stages 1 to 4 show a progressive development of the penis and vas deferens. At a VDS of 5, vas deferens tissue proliferates over the opening of the reproductive tract, blocking it, and subsequently causing sterility due to the inability of the animal to release egg capsules. Aborted egg capsules then gradually accumulate in the capsule gland (stage 6). The vas deferens sequence index, VDSI, is the mean VDS in a given sample of females.

Mesocosm Study ofMytilus edulisLarvae and Postlarvae, Including the Settlement Phase, Exposed to a Gradient of Tributyltin

“…Toxic effects of TBT exposure such as imposex (female snails develop a penis) of the dogwhelk snail, Nucella lapillus (Gibbs et al, 1988;Bailey and Davies, 1989) and reduced growth and enhanced mortality of larvae of bivalves (Thain, 1983;Beaumont and Budd, 1984;Laughlin et al, 1988;Lapota et al, 1993;Ruiz et al, 1995) have been reported. In the United Kingdom, evidence of toxic effects has led to the setting of a U.K. environmental quality standard (EQS) for TBT in seawater of 0.8 ng Sn liter\ (Matthiessen et al, 1995).…”

Tributyltin biomonitoring using prosobranchs as sentinel organisms

“…Furthermore, it allows the interspecific comparison of For all imposex-affected prosobranchs the spatial distribution of imposex in relation to boating activity suggests that these species have potentials as bioindicators of TBT contamination. The imposex phenomenon has been successfully used in TBT biomonitoring studies in Scotland [11][12][13], England [14,15], Ireland [4,16], France [3] and outside Europe, e.g. in the United States [17,18], Canada [19], southeast Asia [20], New Zealand [21,22] and Australia [23,24].…”

Imposex in Nucella lapillus: a ten year survey in NW Brittany

“…The degree of masculinisation of the female dogwhelk Nucella lapillus is known to be related to the level of TBT pollution as a dose-effect process (Bryan et al 1986, Bailey & Davies 1989, Oehlmann et al 1992. It is possible, therefore, to estimate the degree of TBT pollution suffered by the ecosystem through imposex measurements (Gibbs et al 1987).…”