Sex-ratio bias in Laevistrombus canarium Linné, 1758(Gastropoda: Strombidae) from Far North Queensland,Australia

In general, sex-ratios in herbivorous gastropods show a strong female bias, particularly in the family Strombidae of the Indo-Pacific. Previous studies of Indo-Pacific strombs point to an underlying female bias in most species. However, the full spatial extent and potential mechanisms driving this phenomenon are currently unknown. Therefore, we studied two populations of Laevistrombus canarium Linne, 1758 over a four year period to explore sex-ratio bias and to investigate the underlying mechanisms. Furthermore, the current study investigated methods to test for sex-ratio bias in strombs where samples are limited and sampling is problematic We sampled individuals from two reefs in Far North Queensland, Australia, with different benthic compositions, despite their close proximity (approximately 4 km apart). In agreement with previous studies, we also found a strong bias towards females. This bias remained consistent across both locations and changes in benthic substrate. Our findings are consistent with models suggesting inherent genetic factors regulate natural patterns of sex imbalance in these strombs. These findings also suggest that there are as yet unidentified stromb life-history characteristics associated with the origin and maintenance of this phenomenon.