Abstract
Cool nutrient rich waters combined with a rocky coastline extending infratidally make the west coast of South Africa well suited to growth of kelp species. The kelp bed community is compared with the main kelp beds studied elsewhere (Nova Scotia, W. Europe, California). All these areas have cool, nutrient-rich water but the Benguela region differs in that large swells prevail. This paper deals with the determination of faunal and algal boundaries in these kelp beds (composed mainly ofEcklonia maxima andLaminaria pallida), as well as their biomass, in order to build a descriptive model of the food web. The main components of a site representative of the variable kelp beds on the west coast of the Cape Peninsula (Oudekraal) have been identified and quantified in terms of ash-free dry weight and Joules. The study covered an area from the rocky intertidal zone to the rock/sand interface found at a depth of 20 m. The site was divided into different areas (offshore, intermediate, inshore), and these were subdivided into depth zones of 4 m to show up any differences with depth. Different sampling techniques using SCUBA were combined to cover a wide range of organisms in the survey. Horizontal and vertical surfaces were differentiated. Kelp holdfasts were removed as a sampling unit for the infauna study. The distribution data of the organisms, other than kelp, were studied by means of multivariate methods which confirmed the division into inshore, mediate and offshore associations. Differences in faunal and floral composition could be detected between horizontal and vertical surfaces. Kelp biomass data showed high average standing crop in the inshore and mediate locality compared to the low offshore values. Maximum standing crop values, however, were not reduced. Mechanisms regulating the kelp bed structure are discussed. In the inshore and intermediate areas, algal biomass is much higher than animal biomass. A fact emerging from the data is that there is relatively little biomass of grazers; the major primary consumers are filter feeders. Problems of turnover rates are mentioned and an energy flow diagram for the area is proposed and its validity discussed.
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Velimirov, B., Field, J.G., Griffiths, C.L. et al. The ecology of kelp bed communities in the Benguela upwelling system. Helgolander Wiss. Meeresunters 30, 495–518 (1977). https://doi.org/10.1007/BF02207857
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DOI: https://doi.org/10.1007/BF02207857
