Ecosystem Sustainability in the Mara River Basin

Amanda Subalusky and Chris Dutton started working in the Mara River Basin in May, 2008, with authorization and work permits from the Kenya Ministry of Water and Irrigation, and in partnership with the U.S. Agency for International Development (USAID), Florida International University (FIU) and the Worldwide Fund for Nature- Eastern and Southern Africa Regional Programme Office (WWF-ESARPO). Their work was under the umbrella of the Transboundary Water for Biodiversity and Human Health project (MRB-TWB), which aims to develop a transboundary river basin management plan between Kenya and Tanzania through work from the grassroots to the Ministry level.

One major achievement of this project was the completion of an Environmental Flow Assessment for the Mara River Basin, which aimed to identify the Reserve flows that must be left in the river to provide for basic human need and ecosystem sustainability, as called for by the Kenyan and Tanzanian water laws. This study brought together a team of specialists from many disciplines to determine the minimum flow levels necessary to sustain a healthy aquatic ecosystem both for the biodiversity of the world-famous Serengeti-Mara Ecosystem and also for the nearly 1 million people who depend on the water and other ecosystem services provided by the river.

Amanda and Chris’ research in the Mara River has been focused on refining the recommended Reserve using water quality and macroinvertebrates as indicators of a healthy river ecosystem. From September 2008 through August 2009, they conducted water sampling at 11 sites from the upper catchment of the Basin to the border between Kenya and Tanzania. They measured physical parameters of water quality, including temperature, pH, salinity, conductivity, total suspended sediments and turbidity. We will also be analyzing water samples for nutrient and heavy metal loads. At 5 of the 11 sites, they also conducted intensive monthly sampling of the benthic macroinvertebrates, the aquatic insects that live in the rivers. While physical and chemical parameters provide a snapshot of the water quality at the time of testing, these aquatic insects are excellent indicators of water quality over a period of days to months. Because of their sensitivity to changes in flow levels and water quality, and their importance to basic ecosystem function in the river, these insects are critical indicators of the health of the ecosystem.

By relating changes in water quality parameters as well as diversity and abundance of macroinvertebrates with changes in the river’s flow level, this research aims to identify threshold minimum flow levels below which the health of the river ecosystem is in peril.

As Amanda and Chris continue to process water samples and data they collected over the last few years, they are now graduate students at Yale University and are continuing to conduct research on the Mara River. Amanda is studying how large wildlife move nutrients between the savanna and the river, how nutrient levels in the river are impacted by flow level and what the impacts are for the health of the Mara River. Chris is studying the sediment dynamics of the river and tracking the sources of non-point pollution as it enters the Mara and Talek Rivers.

Follow their work by visiting their website; Mara River Research.