3.2. Spatiotemporal Variations in Epifaunal Communities
Both site and season were found to have significant influence on variation in epifaunal abundance within Zostera capensis habitats in Langebaan Lagoon (PERMANOVA, p < 0.001; Table 3.2). Site differences accounted for the largest proportion (36.83%) of the observed variation, which was more than twice the contribution of seasonal differences (17.28%). A significant portion of variation (21.33%) was attributed to the interaction between site and season, while 24.56% of epifaunal variation remained unexplained (Table 3.2). Site differences were evident in the clear spatial separation of epifaunal abundance in the dendogram and MDS plot showing a 60% dissimilarity in two groupings (Fig. 3.2 A&B). One cluster comprised Centre Banks, Klein Oesterval and Oesterval (closer to the mouth), and the other Bottelary and Geelbek (closer to the head of the lagoon).
Beta-diversity differed between sites (PERMDISP: F = 17.8,p < 0.01), with pairwise comparisons confirming differences in abundances between sites at the mouth and those at the lagoon head (pairwise PERMDISP t = 2.48, p < 0.04). The species Siphonaria compressa and Assiminea globulus contributed largely to the observed dissimilarity contributing as much as 91% to the observed variation (Table 3.3). Fissurella mutabilis , Parvulastra exigua , Diogenes brevirostris andPyura stolonifera were the main species accounting for >60% of observed patterns at Centre Banks, Klein Oesterval and Oesterval (Table 3.3).
Although spatially distinct seasonal patterns were not clearly evident, the assessment of individual sites revealed seasonal groupings with varying degrees of similarity, ranging from 25 to 75% (Fig. 3.3). MDS plots separated species abundances in spring from summer, autumn and winter at Centre Banks and Klein Oesterval. In the case of Oesterval, abundances were separated into two groups: spring and summer, and autumn and winter (Fig. 3.3). No distinct seasonal grouping was observed for Bottelary, while at Geelbek, the abundance in autumn appeared to be different from the other seasons (Fig. 3.3). Generally, , there was no significant seasonal effect observed in beta-diversity (PERMDISP:F = 3.24, p = 0.09), however pairwise comparisons revealed significant differences between epifaunal abundances in autumn and winter (pairwise PERMDISP t = 3.31, p < 0.01) and winter and summer (pairwise PERMDISP t = 3.19, p< 0.01).