Abstract:
Experiments were performed to determine the rate of recolonization of sediment-associated microalga and effects of infauna on microalgal biomass and production. Estuarine sediment was defaunated and transplanted to the field and the laboratory. Recolonization of sediment by flora and fauna, relative to control sediment, was measured by chlorophyll a, gross primary production, community O sub(2) uptake and infaunal abundance, sampled at Days 1, 10, and 40. Microalgal colonization in the field was, rapid, with chlorophyll a returning to control levels by Day 10. Infaunal density returned to control levels within 40 d. Removal of infauna in the laboratory, primarily tanaids, increased sediment-associated microalgal growth. After 40 d, chlorophyll a was 4 times greater and gross primary production 2 times greater in the defaunated sediment than in the controls. Grazing of microalgae by infauna appeared to be the mechanism of control. Patterns of
community 0₂ uptake were difficult to interpret and showed no simple relationship with infaunal
density. These experiments indicate that estuarine infauna is one of the factors controlling sediment-
associated microalgal biomass and production.
