Elevation of Testosterone Level in Periwinkle Snail Tympanotonus fuscatus var radula Exposed to Bis-Tributyltin Oxide (TBTO)

Abstract

Bis (tri-n-butyltin) oxide (TBTO) is an organotin biocide used in marine antifouling paints to prevent encrustation of marine organisms on the hull of ships. The release of tributyltin (TBT) from hull of ships represents one of the main problems of direct, diffuse and continue contamination of the marine environment. To assess the effect of TBT pollution in Warri Harbour, Periwinkle snails, Tympanotonus fuscatus var radula an important shellfish in the Niger Delta ecological zone was exposed to sublethal concentrations (0.1, 1.0, 10 and 20μg/L) of TBTO using direct sediment toxicity bioassay to determine TBT bioaccumulation and its effects on testosterone levels. Tissue analysis for TBT was done using Solid Phase Extraction (SPE) and gas chromatography with flame ionization detection (GC-FID) after derivatization with Grignard reagent pentyl magnesium chloride. The study employed the Organization for Economic Development and Cooperation (OECD) Guideline 218 protocol. Tissue analysis of T. fuscatus var radula for TBT was found to be significantly low for TBT. Serum analysis of the Periwinkles snail after 10, 20 and 30days exposure period to varying TBTO concentrations showed increased significantly (p<0.05) free testosterone levels with increased concentration and exposure durations. TBT induced elevated testosterone in snails may be indicative of imposex expression an irreversible sexual abnormality in female molluscs. The observations in this study showed that T. fuscatus var radula is susceptible to imposex development and may affect their reproductive ability which may lead to population decline.

Keywords

• Imposex
• Periwinkle Snail
• Testosterone Elevation
• Tributyltin Oxide