Factors related to the intra – and inter-specific zonation of two pulmonate gastropods Salinator solida (Lamarck) and Ophicardelus ornatus (Ferussac)

Abstract

The distribution of two wetland pulmonate gastropods, Salinator solida and Ophicardelus ornatus, was studied at Towra Point and Kooragang Island, NSW. Indicator species analysis (ISA) showed that both intra and inter-specific zonation occurs. Linear discriminant analysis showed that 87.5% of the variance between five groups formed by ISA was explained by the first two discriminant functions. The first discriminant function was highly correlated with distance from shore, soil salinity and the degree of inundation at each site. The second discriminant function was correlated with cover. The pattern revealed in this study shows large S. solida to be found high on the shore in habitats of poor drainage and high salinity. Small S. solida and O. ornatus are generally found downshore in habitats of regular inundation, good drainage and good cover. Larger O. ornatus and intermediate S. solida were generally found in habitats where the environmental conditions are between these two extremes.