Predominant algae of Goreangab Dam, Windhoek, during early summer

Abstract

Identification of phytoplankton in Goreagab dam was performed since August 2004. Phytoplanktons were identified up to the genera level. The population of phytoplankton was dominated by the genus Microcystis, Cyanophyta. Other abundant algal groups include Chlorophyta especially the genus Chroococcus. About 95 percent of the algae were identified at the magnification of xlO. Microscopic identification revealed that different algal genera can inhabitat one place in water column and some were found attached to others (e.g. Apiocystis spp.). That means a bloom of phytoplankton could accommodate as thousands of phytoplankton genera as the condition permits. Most algal genera has been identified and recorded in previous freshwater studies and results confirmed Microcystis to be the most frequent and widely distributed genera in tropical freshwater impoundments. The samples were preserved in Lugol's solution. Most algal cells appeared red or brown under the microscope and only few persisted to hold their original colour like greenish for Cryptomonas spp.. Results showed that there are many algal genera in Goreagab dam and further investigations are necessary