Project description:Imposex, the superimposition of male sexual characteristics in females, is caused by tributyltin (TBT) and provides one of the best ecological examples of anthropogenically-induced endocrine disruption in aquatic ecosystems. We used combinations of 454 Roche pyrosequencing and microarray technologies to understand the functional genomic basis of imposex in the prosobranch gastropod, Nucella lapillus, a recognised sentinel for TBT-induced imposex.
Project description:Six imposex surveys in the dogwhelk (Nucella lapillus) have been conducted over the past two decades to assess legislation effectiveness controlling the use of tri-butyl tin (TBT) by the maritime shipping industry. This study firstly analysed the results of the 2014 survey and secondly carried out a trend assessment of the same 88 sampled sites between 1997 and 2014 of which 65 showed statistically significant reductions. To highlight the magnitude of change, the Vas Deferens Sequence stages (VDS) of the same 56 sites sampled in 1997 and 2010 showed that the Vas Deferens Sequence Index (VDSI) reduced statistically significantly from 2.89 and 0.42, respectively. These data confirm that the legislation enacted, latterly through the International Maritime Organization (IMO) during 2003 to 2008, has been effective in progressively reducing the impact of TBT in the marine environment. Nevertheless, the 2014 results show that two of 18 sampled sites (Gurnard Bay and St. Mawes) are still above the Ecotoxicological Assessment Criteria (EAC) derived for TBT (VDSI ≤ 2).
Project description:Dispersal has received growing attention in marine ecology, particularly since evidence obtained with up-to-date techniques challenged the traditional view. The dogwhelk Nucella lapillus L., a sedentary gastropod with direct development, is a good example: dispersal was traditionally assumed to be limited until studies with microsatellites disputed this idea. To shed some light on this controversy, the genetic structure of dogwhelk populations in northwest Spain was investigated with highly polymorphic AFLP markers giving special attention to the influence of hydrodynamic stress. In agreement with the expectations for a poor disperser, our results show a significant genetic structure at regional (<200 km) and areal scales (<15 km). However, the spatial genetic structure varied with wave-exposure in the present case study: IBD was evident under sheltered conditions but absent from the exposed area where genetic differentiation was stronger. Our results provide evidence that differences in wave-exposure can exert a detectable influence on the genetic structure of coastal organisms, even in species without a planktonic larva.