Picoplankton of Lakes Tanganyika and Kivu (Eastern Africa): a flow cytometry study

UNREIN, F.; SARMENTO, H.; STENUITE, S.; PIRLOT, S.; GASOL, J. M.; DESCY, J-P.

Krakow (Polonia)

Simposio; 4th Symposium for European Freshwater Sciences (SEFS4); 2005

Flow cytometry is commonly used for the assessment of autotrophic and heterotrophic picoplankton, mostly in marine environments. Large East African lakes are excellent models for this kind of technique in freshwaters because of their oligotrophy and high picoplankton abundance. In addition, current estimates of microbial populations in these systems suggest they have a large importance. Lakes Kivu and Tanganyika are two examples of large, deep and meromictic tropical lakes. The <2µm fraction represents 60% of total phytoplankton chlorophyll a in Lake Tanganyika (south basin) and 25% in Kivu (North basin). Flow cytometry counts were completed with epifluorescence microscopy for biomass estimates. Heterotrophic picoplankton is mainly constituted by bacteria, which play a central role in nutrient recycling, in biogeochemical processes, and in organic matter production, similarly as they do in the ocean.