Aspects of growth, recruitment and conservation of the Brown Mussel Perna perna along the Tsitsikamma Coast

Abstract

Beds of brown mussels Perna perna are a dominant feature of the lower tidal range of rocky shores in the Tsitsikamma Coastal National Park. Mussels in this region attain a length of 30-40 mm by the end of their first year, and the majority probably exceed 50 mm at two years of age. Secondary settlement of plantigrades occurs from midspring through early winter, especially in summer and early autumn, and growth of adult forms is slowest prior to this settlement. Settlement occurs serially and powerful cohorts may be formed. At Nature's Valley density and biomass of mussels inside the park's boundary are significantly higher than in non-protected areas. Older age groups are also more abundant within the park.