<smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="place"> Imposex in rock whelks <i style="">Thais</i> and <i style="">Ocenebra </i>species (Mollusca, Neogastropoda, Muricidae) from Gujarat coast </smarttagtype>

Abstract

<smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="place"> Imposex in <i style="">Thais bufo, T. rudolphi, T. tissoti</i> and <i style="">Ocenebra bombayana</i> was observed from Saurashtra coast of Gujarat. The maximum percentage of imposex out of total sample size (44.80 and 46.55%) were observed at Porbandar in <i style="">T. bufo</i> and <i style="">T. rudolphi</i> respectively while <i style="">T. tissoti</i> and <i style="">O. bombayana</i> at Mahuva showed 10.29 and 9.72% of imposex respectively. The percentage conversion of potential females to imposex was minimum at Diu and maximum at Porbandar. The number of ships operated from Porbandar and Diu directly correlated with severity of CPFII and percentage of imposex at these places. The results indicate that severity of imposex in <i style="">T. rudolphi</i> could be utilized as a bioindicator of TBT contamination in the marine environment. The Relative Penis Size Index(RPSI) ranged from 3.24 at Veraval to 16.50 at Porbandar in <i style="">T. bufo</i> while in <i style="">T. rudolphi </i>it ranged from 44.26 at Okha and 55.96 at Veraval. It was 21.19 and 14.26 for <i style="">T. tissoti</i> and <i style="">O. bombayana</i> respectively. The results indicate that RPSI may not be a foolproof indicator of severity of imposex in these organisms. Therefore a new index has been developed which is termed as Conversion of Potential Females to Imposex Index (CPFII) to calculate the potential females of a given area of a population. It seems the causative agents in seawater is neither toxic nor growth inhibitory at all the places of study but it interferes with the reproductive mechanisms and morphogenesis in these four species. The imposex in these organisms and its relation to TBT concentration in the marine environment is discussed. </smarttagtype>