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).