Dr Yusuph Aron Kafula

Tanzania | The dramatic decline in freshwater biodiversity is partly related to changes in temperature conditions. The predicted rise in global temperature poses a substantial threat to and contributes to the extinction of aquatic species. This loss of biodiversity resources can be linked to a severely negative impact on socio-economic wellbeing through the dwindling of fisheries resources, which are an affordable protein source for most resource-poor communities. Increased agricultural activity and urbanisation pose additional threats that simultaneously impact freshwater ecosystems.

In Tanzania, where agriculture and urbanisation are rapidly intensifying, only about 50% of sprayed pesticides reach targeted crops, with less than 0.5% eventually reaching the targeted pest. Research on the effects of artificial light at night on terrestrial life has shown profound consequences for their biology and ecological functioning. Yet, how this affects freshwater life has not received much attention.

The individual effects of increased temperature, chemical pollution, and artificial light at night on freshwater life, as well as their combined effects, are not yet fully understood. Considering the importance of these systems for biodiversity and their services to local communities, this remains a cumbersome situation, as temporary freshwater ponds provide water for irrigation or domestic purposes and serve as drinking places for cattle. They are often also biodiversity hotspots and watering holes for large wild mammals, such as buffalo and elephants.

Before their registration and use, agricultural pesticides are typically subjected to ecological risk assessments that inform environmental policies and regulations, enabling the prediction and mitigation of their impact on freshwater ecosystems. In contrast, in many countries of sub-Saharan Africa, registration of new agricultural chemicals relies solely on their efficacy against targeted pests, without considering independent ecological risk assessments tailored to these countries' often specific environmental conditions and biota.

While the higher sensitivity of local temporary pond species has been well-recorded in laboratory settings, fewer field-based studies exist on the impact of stress exposure on these organisms in more realistic field settings. By extension, the effect of stressors on the structure of temporary pond communities and the overall ecological functioning of these systems remains poorly understood. With the increasing intensity of anthropogenic stressors, the sensitivity of local species may be even higher, and extrapolation from traditional toxicity tests may no longer be adequately protective.

Dr Yusuph Aron Kafula's research project focuses on understanding and addressing chemical pollution, assessing the acute toxicity of cypermethrin, abamectin, and chlorpyrifos under various temperature and light exposure scenarios in selected temporary pond species. It will determine the combined effects of sub-lethal cypermethrin, abamectin, and glyphosate exposure, as well as temperature and prolonged light exposure, on life history and physiological traits of temporary pond species. Under field-based mesocosm settings, he will study temporary pond community structure and functioning under multiple stressor scenarios. To ensure the long-term conservation of freshwater ecosystems, it aims to promote the co-formulation of management guidelines for sustaining temporary pond ecosystems among different stakeholders.

Upon completion of the project, safe pesticide concentrations of commonly used insecticides under increased temperature and prolonged light exposure will be identified. Physiological and life history traits of temporary pond species under simultaneous exposure to temperature increase, pesticide, and prolonged light exposure will also be established. The impacts of multiple stressors on invertebrate abundance and diversity, fish life history traits, nutrient levels, and phytoplankton biomass will also be ascertained. Using generated science-based evidence, Dr Kafula will, in collaboration with different stakeholders, draft a community-based management guideline to regulate pesticide use adjacent to freshwater ecosystems. This will contribute to improved pollution management and more effective measures to conserve and sustain aquatic biodiversity in the face of a changing climate and increased exposure to artificial light.

Dr Yusuph Kafula combines short– and long-term exposure tests to inform context-specific ecological risks of chemical pollution, increasing temperature, and prolonged use of artificial light in freshwater ecosystems. He is a lecturer at Mwalimu Julius K. Nyerere University of Agriculture and Technology, Tanzania. Dr Kafula holds a PhD in Biology, majoring in Aquatic Ecology and Ecotoxicology from KU Leuven, Belgium and an MSc in Health of Aquatic Animals from Sokoine University of Agriculture, Tanzania. His research interests include aquatic sciences, Ecological Risk Assessment, Aquaculture, and Ecotoxicology.