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Differential response of phytoplankton to additions of nitrogen, phosphorus and iron in Lake Tanganyika |
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| Authors: | AAIKE DE WEVER KOENRAAD MUYLAERT DENIS LANGLET LAURENT ALLEMAN JEAN-PIERRE DESCY LUC ANDRÉ CHRISTINE COCQUYT WIM VYVERMAN |
| Institution: | Laboratory for Protistology and Aquatic Ecology, Department Biology, Ghent University, Ghent, Belgium; K.U.Leuven-Campus Kortrijk, Kortrijk, Belgium; Musée Royal de l'Afrique Centrale, Section de Pétrographie-Minéralogie-Géochimie, Tervuren, Belgium; Laboratory of Freshwater Ecology, Department of Biology, University of Namur, URBO, Namur, Belgium; Département Chimie et Environnement, Ecole des Mines de Douai, Douai, France; National Botanic Garden of Belgium, Meise, Belgium |
| Abstract: | 1. In order to evaluate limitation of different phytoplankton groups by inorganic nutrients, multiple nutrient enrichment bioassays using the addition of iron (Fe) and the combined addition of nitrogen and phosphorus (NP) were carried out in the north and the south of Lake Tanganyika during the rainy and dry seasons in 2003 and 2004. 2. Nutrient additions resulted in an increase in phytoplankton growth rate relative to control treatments in all experiments. HPLC pigment data and epifluorescence microscopy counts indicated differential stimulation of the dominant phytoplankton groups. Iron additions mainly stimulated prokaryotic picophytoplankton, while enrichments with nitrogen and phosphorus stimulated green algae and in some cases diatoms. Extended incubation (3 days) indicated co‐limitation of Fe and NP, in particular for picocyanobacteria. |
| Keywords: | iron Lake Tanganyika nutrient limitation phytoplankton picocyanobacteria |