Climate change is altering lake ecosystem functions and affecting livelihoods of rural communities dependent on the ecological services of climate-sensitive waterbodies. Anthropogenic pressures may undermine ecosystem resilience and amplify human vulnerability to climate change. At Lake Bosumtwi, climate change has altered the lake’s limnology, resulting in fish decline. Sustainability of the watershed and fish resources is threatened by climate and anthropogenic stressors whose individual and synergistic effects on ecosystem function are unknown. New livelihoods emerging from adaptations to poor fish harvest are altering land use patterns within the watershed with unknown implications for lake health and its ability to rebound from climate impacts and anthropogenic pressures. Our project will resolve the complex interactions at the ecosystem and watershed scale and investigate the dynamics within the socioecological system. This information will be used for policy and management of the Bosumtwi watershed. With high resolution monitoring of lake physics, biogeochemistry, primary production, fisheries, land use changes, sedimentation and livelihood adaptive mechanisms, we aim to collect the most comprehensive dataset in West Africa. These data will be used to develop models that incorporate climate, lake, fisheries and land-use variability to predict the effect of climate and human activities on ecosystem function and fisheries. Our project will harness Ghanaian, Danish and German expertise to interpret complex climate-lake-watershed interactions with novel application of models. Research results will be disseminated to stakeholders through several mechanisms including hands-on workshops coinciding with the project annual meetings. The long-term goal of the project is to build ecosystem resilience and reduce vulnerability by promoting sustainable fisheries, livelihoods and watershed management through the training of scientists, students and managers.
Successful monitoring of climate, lake physics, chemistry and primary productivity of lake Bosumtwi with state-of-the-art equipment have yielded high-resolution data which indicates persistent stratification and incomplete mixing of the water column evident of climate warming which may be causing reductions in fish stocks. The ecosystem model (GOTM-FABM-PC lake) has been set up and calibrated based on historical data. Validated classified land use and land cover maps for the watershed over the period 1986-2018 shows that lake volume has shrunk by 3.7 % while 22.6 % of closed and open forests have been lost to farmlands, built-up areas and bare lands due to livelihood diversification in response to ecosystem change and fisheries decline. Lake fish stocks are low, overexploited and poorly managed. Livelihood assessment indicates a gradual shift from fishing to farming. However, fishermen without options have intensified fishing efforts to further exploit the limited fish stocks.