Hydrobia ulvae imposex levels at Ria de Aveiro (NW Portugal) between 1998 and 2007: a counter-current bioindicator?

Abstract

Imposex expression in prosobranch gastropods has been widely used as a biomarker of tributyltin (TBT) pollution. Estuaries have been described as the most affected areas by this problem since they usually enclose the main TBT sources-ports, dockyards and marinas-resulting from the compound's application as a biocide in antifouling paints on ships. Using Hydrobia ulvae as a bioindicator, the current work addresses the most reliable methods to reduce the influence of critical variables, such as the animals' size, on imposex levels assessment for TBT pollution monitoring and presents its temporal trends from 1998 to 2007 in Ria de Aveiro (NW Portugal) to evaluate the effectiveness of recent legislation applied to reduce TBT environmental levels. H. ulvae imposex levels did not decrease in this estuarine system during the last decade despite the implementation of the EU Regulation No. 782/2003. Instead, there was a global significant increase in the percentage of females affected by imposex and a slight increase of the vas deferens sequence index (VDSI), contrasting with what has been described for other bioindicators in the same study area. These results show that different biology/ecology traits determine distinct routes of TBT uptake and/or bioaccumulation, pointing the importance of choosing the bioindicator depending on the compartment that is being monitored (sediment vs. water). Sediment ingestion as feeding habit is discussed and pointed as a reason to choose H. ulvae as a bioindicator of TBT pollution persistence in sediment. It is therefore predicted that the response of different prosobranch species around the world may diverge according to the compartment that is being monitored and that female masculinisation may not be completely eradicated in the near future due to TBT persistence in sediments.

Imposex reduction and residual butyltin contamination in southern Brazilian harbors

“…First, the sampling was conducted in the same month to avoid seasonal variability in penis length, which is regulated by the reproductive cycle of S. haemastoma. A similar situation was observed for Hidrobia ulvae during a temporal trend study at Rio Aveiro, Portugal [28]. In addition, only adult animals (>20 mm) were collected, and the same method was used for imposex determination allowing consistent data interpretation.…”

“…The imposex parameters, mainly RPLI, are frequently influenced by animal size, even when the sample is composed only by adult animals [28]. All statistical analyses were performed in Statistica software (Ver 6.0; Statsoft) with a significance level of 0.05.…”

High tributyltin and imposex levels in the commercial muricid Thais chocolata from two Peruvian harbor areas

“…Considering that the rock snail T. chocolata is a subtidal carnivorous muricid that lives over hard substrates (feeding mainly on mussels and barnacles that, ultimately, accumulate from the water column) and is ecologically similar to N. lapillus, its apparently high capacity to bioaccumulate BTs may reflect contamination predominantly from the water column [43][44][45]. Considering that the rock snail T. chocolata is a subtidal carnivorous muricid that lives over hard substrates (feeding mainly on mussels and barnacles that, ultimately, accumulate from the water column) and is ecologically similar to N. lapillus, its apparently high capacity to bioaccumulate BTs may reflect contamination predominantly from the water column [43][44][45].…”

Nucella lapillus L. imposex levels after legislation prohibiting TBT antifoulants: temporal trends from 2003 to 2008 along the Portuguese coast

“…The other objective is to create an imposex level baseline at the moment when the IMO TBT-based AF paints global ban came into force. As some factors have been described to induce variation in imposex assessment indices, [17][18][19][20][21] which might result in less reliable results, new monitoring and data analysis procedures are described.…”