Vertical gradients in the fauna and oxidation of two exposed sandy beaches

Abstract

Vertical profiles of oxygenation and fauna were measured in two exposed sandy beaches. At the less exposed site the whole upper metre of sediment was oxidized although the redox potential discontinuity started at 85 cm. Meiofauna were concentrated in the upper 40 cm and protozoa in the upper 55 cm, but bacteria showed no distinct vertical drop-off in numbers. On a more exposed beach the upper 1,3 m was highly oxidized, with meiofauna concentrated in the upper 80 cm and protozoa in the upper 115 cm. Meiofauna and protozoan numbers correlated with oxygen tensions and redox values and with each other. It is suggested that small protozoans are an important food source for the meiofauna.