The effects of a single freshwater release into the Kromme Estuary. 2: Microalgal response

Abstract

The release of freshwater from the Mpofu Dam in November 1998 resulted in a short-term (6 d) longitudinal and vertical gradient of both salinity and nitrate in the estuary. There was no significant increase in phytoplankton chlorophyll a during the period of the study. The phytoplankton communities were dominated (> 10%) by diatoms and flagellates throughout the study. The average number of diatoms increased significantly from 301 cells·ml-1, prior to the release, to a maximum of 3 856 cells·ml-1 by the end of the first spring tidal cycle. The average number of flagellates increased from 1 903 cells·m l -1