The use of stable carbon isotopes as tracers of ecosystem functioning in contrasting wetland ecosystems of Lake Victoria, Kenya

Aquatic macrophytes and sediments from two contrasting wetland ecosystems of Lake Victoria, Kenya (Lower Sondu Miriu and Kibos systems) were analyzed for their stable carbon isotopic composition in order to observe patterns in system functioning in these two ecosystems. The aquatic macrophytes had carbon isotope ratios ranging from −8.92 to −29.18 per mil (parts per thousand difference from the reference). For the dominant macrophytes, we observed most 13C enriched values for Cyperus papyrus and most 13C depleted values for Eichhornia crassipes. On transects from the river to the lake, Kibos sediments maintained lower carbon isotope signatures compared to the Lower Sondu Miriu sediments. The possible causes of the observed variation in the δ13C signatures from sediments and aquatic macrophytes in the two-wetland ecosystems are outlined.