Effects of predation on the size structure of the gastropod Salinator solida (Martens) populations at Towra Point, NSW, Australia

Abstract

The pulmonate gastropod Salinator solida inhabits intertidal mangrove and saltmarsh communities throughout New South Wales. Studies at Towra Point and elsewhere have consistently found that the mean size and range of size/age classes increases with height on shore. Afield experiment was undertaken to test the hypothesis that predation was responsible for reductions in the mean size of individuals inS. solida populations in the upper mangrove forest. Twelve months after the establishment of fenced plots, there were significantly more individuals in the fenced plots than in unfenced or partially fenced control plots; the number of snails in the 4.1–8.0 mm and > 8.1 mm size classes had increased in the fenced plots but not in the control plots. The results suggest that predation is a major factor determining variation in population size structure by acting to significantly reduce the abundance of adults in the upper mangrove forest.