INTERTIDAL ZONATION OF MACROFAUNA AND STRATIFICATION OF MEIOFAUNA ON HIGH ENERGY SANDY BEACHES IN THE EASTERN CAPE, SOUTH AFRICA

Summary

Intertidal macrofauna on high energy beaches in the East Cape occurs in two zones: a lower zone dominated by Bullia rhodostoma, Donax sordidus and Gastrosaccus psammodytes; a midlit-toral zone starting about 0,9 m above extreme low water of spring tides and extending to about 1,9 m above ELWS is wetted on every tide and is dominated by Donax serra, with isopods also present. There is no upper zone or subterrestrial fringe, probably due to the absence of a distinct drift line. Meiofaunal distribution has been divided into four strata in the sediment: a dry sand stratum in the upper sediment near the top of the shore is wetted only at high tide and its meiofauna is predominantly nematodes; a moist sand stratum underlies the dry sand down to the permanent water table and here a rich and diverse meiofauna, usually dominated by crustaceans, occurs; a water table stratum at and below the permanent water table has lowered oxygen tensions and moderate meiofauna numbers dominated by nematodes and crustaceans; a low oxygen stratum underlies the water table stratum and here low numbers of meiofauna, predominantly nematodes, occur. Factors influencing these zones and strata are discussed and the conditions on other beaches are contrasted with those studied here.