Studies on the Psammolittoral meiofauna of Algoa Bay, South Africa II. The distribution, composition and biomass of the Meiofauna and Macrofauna

Abstract

Two beaches in Algoa Bay, South Africa, have been found to support a relatively rich and varied meio-fauna. Highest numbers were recorded at HW on the sheltered beach (2 250/10 cm¹) and the lowest numbers at LW on the same beach (60/10 cm¹). On the exposed beach numbers were more uniform but were highest between MW and LW. Distribution of the meiofauna on the sheltered beach was limited mainly by the amounts of available oxygen in the interstitial water while on the exposed beach amounts of available food, and to a lesser extent oxygen, were limiting. The meiofauna of the sheltered beach was dominated by nematodes and that of the exposed beach by Crustacea (harpacticoid cope-pods and mystacocarids). Meiofauna biomass values were highest in winter and lowest in summer. Macrofauna was richer on the exposed beach, mainly due to the sand mussel, Donax serra. Production estimates based on standing crop indicated that the meiofauna may account for 55 percent and 28 per cent of the total secondary production on the sheltered and exposed beaches respectively.