My research team studies the biodiversity and ecosystem dynamics of Lake Tanganyika. We use field surveys, experiments, and environmental chemistry analyses to understand how so many species arose and coexist. We also work with partners to document rapid changes in Tanganyika’s ecology due to overfishing, sedimentation, and climate change.
Lake Tanganyika is a crown jewel of global biodiversity and ecosystem services, and it is a privilege to study it. As the oldest and deepest of African lakes, Tanganyika is home to >800 endemic species. These species are distributed around the shoreline, which supports an important subsistence fishery and provides water for human settlements. The open waters of the lake provide a remarkably productive commercial harvest of sardines and their predators–one of the world’s largest freshwater fisheries. Despite these notable statistics, Tanganyika is poorly understood in terms of within-lake biogeography and ecosystem dynamics, and managing this massive lake to ensure sustainability is a challenge for the four riparian nations and their NGO partners.
In collaboration with colleagues from the Tanzanian Fisheries Research Institute and The Nature Conservancy, my team from UW-Madison studies the ecology of Lake Tanganyika, and how it is being changed by climate warming, overfishing, and sedimentation. We have found that the lake’s waters are warming rapidly, leading to less physical mixing of its depths. The stabilization of the water column effectively traps nutrients in the bottom waters, reducing the productivity of algae and animals. New work on sediment cores indicates that climate change has played a key role in governing lake productivity and habitat availability in the long term, but that warming over the last century has reduced fish stocks to their lowest levels ever. Intensive fishing pressure is imposed on the remaining fish stocks, and threatens to lead to collapse of this critical resource that feeds tens of millions of people in four nations. We have also documented extensive alteration of the nearshore ecosystem when deforestation leads to silt accumulating on rock surfaces.
Together with partners from Wright State University and the University of Wyoming, we are documenting this wide range of problems, and advising governments and NGOs on strategies to minimize threats to the critical ecosystem services and remarkable biodiversity of Lake Tanganyika.