3.1.1. Abundance
Epifaunal abundances exhibited a distinct gradient of increase from the mouth to the head of the lagoon (Fig. 3.1A). Bottelary displayed the highest abundances across all seasons (136.68 m-2) followed by Geelbek (83.78 m-2). This was due to elevated densities of Assiminea globulus and Siphonaria compressa . Oesterval exhibited an average species abundance of 79.14 m-2, while Centre Banks registered a slightly lower average abundance of 68.84 m-2. In contrast, Klein Oesterval recorded the lowest abundance among the surveyed sites (23.66 m-2). These sites were dominated by Sargartia ornata . Centre Banks supported the greatest average abundance ofFissurella mutabilis (26.55 m-2), while the hermit crab, Diogenes brevirostris was most abundant at Klein Oesterval (36.74 m-2). A. globulus was also prevalent at high shore sites at Oesterval while F. mutabilis was exclusively found at sites closer to the mouth and absent at Bottelary or Geelbek. Similarly, A. globulus was not detected at Centre Banks and an average of 1.26 individuals was recorded at Klein Oesterval in winter.
Differences in abundance were significant across sites (F = 10.80, p < 0.001, Fig. 3.1A). Mean abundances at Centre Banks and Klein Oesterval were similar while Oesterval, Bottelary and Geelbek displayed homogenous means (Tukey HSD, p < 0.05, Fig. 3.1A). Despite the high abundance (252.93) of individuals at Centre Banks in autumn there were no significant seasonal differences in abundance between sites (F = 2.66, NS), however, the interaction between site and season proved significant (F = 6.68, p< 0.001).