Plankton composition and cycling of carbon during the rainy season in a tropical coastal ecosystem, Zanzibar, Tanzania

Biomass, species composition and production of the planktonic communi, were investigated during the rainy season in May and June 1999 outside Zanzibar Island, Tanzania. In general, the plankton biomass of different organisms was uniform between depths as well as over time. The integrated water colum n primary production ranged from 204 to 4142 mg C m(-2) day(-1). Bacterial production varied between 10 and 72 mg C m(-2) day(-1), comprising similar to5% of the total bacterial standing stock. The data obtained from these ex periments are summarized in a carbon budget. At the most 77% of the total p rimary production channelled through the heterotrophic flagellates, ciliate s and heterotrophic dinoflagellates to higher trophic levels. Of the estima ted carbon demand for mesozooplankton, 28% could potentially be met by cili ates and heterotrophic dinoflagellates.