Influence of Environmental Variables on Planktonic and Phytobenthic Communities in Earthen Ponds at Makoba, Zanzibar

Abstract

A study was conducted between July 2002 and June 2003 to assess the role of salinity, temperature, pH and dissolved oxygen on the abundance of planktonic (phyto- and zooplankton) and phytobenthic (algal mats) communities in shallow (40 cm depth) earthen ponds at Makoba, Zanzibar. Among the zooplankton, rotifer abundance peaked during the rainy period (salinity of 27–42‰) while protozoa and copepods were most abundant during the dry period (max salinity of 70‰). However, no season effects were seen on the phytobenthos. The most abundant genera were Pseudonitzschia sp., Schizothrix sp., Microcoleus sp. and Oscillatoria sp. and in general, algal mats were available throughout the year. Other variables such as temperature, pH and oxygen concentration did not show significant fluctuations over the study period.

Keywords: earthen ponds, planktonic organisms, algal mats, environmental variables

West Indian Ocean Journal of Marine Science Vol. 3 (2) 2004: pp. 123-134