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).