Imposex study on Thais aculeata (Gastropoda: Muricidae) in Ambon Bay, Eastern Indonesia

Abstract

Abstract Study on imposex of Thais aculeata was conducted in September to October 2016 in Talake Shipyard, Ambon Bay. The aim of this study was to investigate and describe the imposex insidence in muricids T. aculeata. Level of imposex was calculated using some indices i.e. RPLI (Relative Penis Length Index), RPSI (Relative Penis Size Index) and PI (Percentage of Imposex). A total of 110 individuals T. aculeata consisted of eight size classes were found, which 39 females individuals were identified to be exposed of imposex. Females with imposex were characterized by the presence of pseudopenis in the form of a small bulge on the top right of the tentacles. Pseudopenis relatively smaller than that of male penis size i.e. 2.13 mm while male penis size was 4.95 mm. Percentage of imposex of T. aculeata was 41.05%, RPSI was 7.97; RPSI was 49.58, and sex ratio of male and female individuals was 1:6.3 The correlation between class size shell with imposex was moderate relationship (R = 0.44). Ratio between number of male individuals and female with imposex was significantly different, but ratio between normal females and females with imposex; and shell length average between normal females and females with imposex was not significantly different, respectively.