The Ichthyofauna Associated with an Intertidal Creek and Adjacent Eelgrass Beds in the Kariega Estuary, South Africa

Abstract

The structure and functioning of salt marsh fish communities in the overall ecology of southern African estuaries is poorly understood. This study compares the ichthyofauna associated with a salt marsh creek and eelgrass bed in an attempt to evaluate the relative importance of these habitats to fishes. Taylor's salt marsh creek and adjacent eelgrass bed in the Kariega Estuary were sampled twice per season between the winter of 1992 and the autumn of 1994. The average density and standing stock of fishes were found to be considerably higher in the eelgrass bed than in the intertidal creek. Both habitats had similar fish diversities but were dominated by different taxa, the most notable of which was the dominance of mugilids in the creek and their scarcity in the eelgrass. Taylor's intertidal creek and adjacent eelgrass beds were dominated by juvenile fish, with both habitats functioning as nursery areas for juvenile fish, albeit for totally different ichthyofaunal communities. The similar fish diversities but lower abundances in the intertidal creek compared to the eelgrass beds are in contrast to similar North American studies, and refute the hypothesis that intertidal salt marsh creeks have higher fish densities but lower diversities than eelgrass beds.