Limitation of Algal Growth in Some Central African Waters

Levels of inorganic nutrients (nitrate, phosphate, sulfate) available for algal growth in nine bodies of water in Malawi were investigated, using enrichment bioassays with naturally present algae as test organisms. Nitrate or nitrate plus phosphate were potentially limiting to algal growth. There was no evidence of sulfate limitation. The relevance of enrichment bioassays to whole water body situations is considered. A model, illustrating invalid use of assays in the interpretation of seasonal succession in algal communities, is discussed.