Imposex in Thais gradata as a Biomarker for TBT Contamination on the Southern Coast of Peninsular Malaysia

Abstract

Thais gradata samples were collected from six locations along the southern shores of Peninsular Malaysia and analyzed for imposex incidence and organotin (butyltins (BTs), including tributyltin, dibutyltin, and monobutyltin, and phenyltins (PTs), including triphenyltin, diphenyltin, and monophenyltin concentrations), in tissue burden. On average, the BT levels were found to be higher than the levels reported a year before for other biota. In contrast, the PT compounds were found to be lower than in the previous report. The present study also classified the morphological expressions of the imposex scheme for this species into seven stages (stage 0 to stage 6) by observing the development of vas deference sequence (VDS) and penis bulk. This latest imposex scheme clearly indicates the mechanism of VDS growth, the structural changes from penis bulk to a penis with flagellum, and from a normal vaginal opening to a swollen vaginal opening. The degree of imposex was assessed using the vas deference sequence index and the percentage of females possessing the imposex characteristics. It was found that locations possessing high imposex levels also tended to show high BT levels in the snail tissue samples. However, correlation analysis did not show a significant relationship among the two parameters. A better result could be obtained if more samples and sampling locations were added in order to prove the hypothesis. The nonsignificant correlation between the shell height and any of the organotin compounds, along with no significant differences between BT levels in female and lower imposex stage samples, suggests that the BT concentration detected was a recent contamination.

Imposex reduction and residual butyltin contamination in southern Brazilian harbors

“…Even so, the TBT levels and BDI values in S. haemastoma tissues indicated a fresh exposure to OT, because TBT predominated in most of those samples. However, levels were not as high as those at the heavily contaminated site [17,36]. Stramonita haemastoma feed on filter feeder organisms, so its levels might reflect an accumulation from the water column (dissolved plus suspended matter).…”

“…However, levels were not as high as those at the heavily contaminated site [17,36]. At all of its sites, a significant VDSI reduction was seen in Paranaguá Bay between 2006 and 2010.…”

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]. In fact, because Thais species have been used as sentinel of TBT pollution in several countries [21,24,[46][47][48], their relative sensitivity must be studied further. In any case, despite the fact that inputs and metabolic routes are still unclear, these strong and significant correlations between imposex indexes and BT concentrations suggest that T. chocolata is a good indicator of OT contamination and could be used as a monitor for future studies in Peruvian coastal areas.…”

“…In any case, despite the fact that inputs and metabolic routes are still unclear, these strong and significant correlations between imposex indexes and BT concentrations suggest that T. chocolata is a good indicator of OT contamination and could be used as a monitor for future studies in Peruvian coastal areas. In fact, because Thais species have been used as sentinel of TBT pollution in several countries [21,24,[46][47][48], their relative sensitivity must be studied further.…”

Concentration of Organotin and Booster Biocides in Sediments of Seagrass Area from Sungai Pulai Estuary, South of Johor, Malaysia

“…OT compounds are poorly biodegradable and have the potential to remain long in the aquatic environment, which can cause deleterious effects towards marine organisms. The effects of TBT in marine environment include acute toxicity [6][7][8][9][10], bioaccumulation in the organism [11][12][13][14][15][16][17], imposex [18][19][20][21] followed by a decrease in reproductive viability of marine organisms. In October 2001, the International Maritime Organization adopted the International Convention on the control of Harmful Anti-fouling System (AFS Convention) that banned the use of OT compounds as a substance in ship antifouling paints starting from 2003.…”