Phenology of Sargassum spp. (Sargassaceae, Phaeophyta) from Reunion Rocks, KwaZulu-Natal, South Africa

Abstract

The density, standing stock, reproductive periodicity and alginate yields have been investigated for a mixed Sargassum species population at Reunion Rocks, KwaZulu-Natal, South Africa. The population consists of two dominant components, Sargassum elegans Suhr and a second species, here termed Sargassum sp. 1. Sargassum elegans typically makes up more than 70% of the population which is heterogeneous in both biomass and density distribution. These species share the same macro-scale distribution within the site and display the same periods of growth and senescence. Standing stock dropped in the cooler winter months and reached a maximum in the hot summer months. Biomass was correlated to one month antecedent minimum, maximum and mean air temperature. Density patterns followed a similar pattern and biomass increased with density. Alginate yield of both species peaked in the warm summer months and was lowest during the cooler winter months. Reproduction peaks were recorded in the cooler months after the peak in biomass and density.