Macro-benthic invertebrate assemblages in the Betty's Bay Marine Protected Area (Kogelberg region South Africa)

The Betty's Bay Marine Protected Area (MPA) was established to protect endangered species like the African penguin (Spheniscus demersus), abalone (Haliotis midae) and the west coast rock lobster (Jasus lalandii). Very little is known about the effects their protection has had on other assemblages within the MPA. To this end, a photo-quadratic survey of the macro-benthic invertebrates was conducted to provide more information on these communities. The photo-quadratic survey was conducted within two depth zones at 10 sites, seven inside and three outside the MPA. Representative samples were collected to assist in the identification of organisms. Eight hundred and eighty one photo-quadrats were analysed to determine percentage cover, diversity and community structure of the invertebrate assemblages. A mean evenness of 0.88 species was recorded for the entire study area and a total of 250 species were documented. Location (inside or outside MPA) had a significant effect on species richness (F1,637.4=32, p<0.001) and diversity (F1,5.47=24.18, p<0.001), while depth had a significant effect on percentage cover (F1,761=5.9, p<0.05) and community structure. Colonial taxa such as Porifera, Cnidaria and algae were dominant, while semi-motile Mollusca were in relatively low abundance.