Browsing by Author "Wilby, Deborah"

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    Shallow subtidal seaweed communities of the Agulhas Marine Province of South Africa
    (2009) Wilby, Deborah; Bolton, John J; Anderson, R J
    Several aspects of seaweed ecology are poorly studied and documented in South Africa, especially the subtidal algal communities along the south coast. This study aims to investigate these communities where few other studies have been conducted. Sampling of shallow subtidal seaweed communities was undertaken at eleven sites along the south coast of South Africa from Still Bay to Mzamba. At each site a number of quadrats were placed within the shallow subtidal zone ranging in depth from O.3m to 2.5m. Within these quadrats all algae were destructively sampled (excluding encrusting algae), invertebrate grazers present were counted, and environmental measurements were taken. These environmental measurements included depth and slope, with temperature data supplied from a previous study. The biogeographical communities of this area were investigated using Detrended Correspondence Analysis, Canonical Correspondence Analysis and cluster analysis, in order to compare them with previous studies on the marine biogeography of the area. In the 85 quadrats that were sampled, 97 species of Chlorophyta, Phaeophyta and Rhodophyta were found. Articulated (or geniculate) coralline red algae were very abundant in the samples, with 17 species that contributed over 44 of the biomass. There was a high number of other red algal species (54 species) but they represented only 10 of the total biomass. Green algal species were not very common (there were only 12 species) but they contributed 42 to the biomass. There were a similar number of brown algal species (14), although they only contributed 2 of the total biomass.