Patterns of vertical distribution and temporal changes of rockyshore intertidal limpets in rock pools at Dwesa-Cwebe Nature Reserve
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Abstract This study investigated the vertical distribution and temporal changes of limpet species. Species diversity was measured in terms of number of limpet species. Sampling was conducted at Dwesa-Cwebe Nature Reserve and two sites with approximately 1.5 km apart were selected. In each site, three rock pools were chosen: MLWS (mid low water shore), MHWS (mid high water shore) and HWS (high water shore). ANOVA results revealed that no significant differences on species diversity, implying the importance of biological processes such as recruitment rather than physical processes. Despite seasonal differences in environmental conditions, the limpet species occurred across the three shore heights. Although there were significant differences in mean sizes (shell lengths) in three (Cellana capensis, Siphonaria serrata Helcion concolor) out of seven limpet species found, there were significant interaction of season and site, indicating that the mean shell length had significant effects in some seasons but not others. Where there were significant differences, mean shell lengths decreased with a decrease in shore height and vice versa. Mean temperatures and salinities increased significantly with an increase in height. They also showed significant differences among seasons and between sites, suggesting temporal and spatial variations on small scales (1.5 km).