Histopathological disturbances in two fish species Oreochromis niloticus (Linnaeus 1758) and Labeo barbus pellegrini (Bertin et Estève 1948) from downstream mining sites in the upper Ulindi and Elila river basins, Eastern DR Congo

peer reviewedThe effect of intensive mining on the health status of fish living in the upper basins of the Ulindi and Elila rivers was investigated between June 2018 and March 2022 by comparing the reproductive, hepatic and gill systems of fish collected from sites upstream and downstream of the mining sites. Biometric indices and organ histopathology are biomarkers that were studied at two different trophic levels using two fish species Oreochromis niloticus and Labeobarbus pellegreni. Histological evaluation was performed on the liver, gonads and gills of both species. Water and sediment samples were analysed for total mercury (T-Hg) concentration by (atomic absorption spectrophotometry). Histological changes were assessed semi-quantitatively, and the results were graded according to the severity of the histological responses. The results showed that L. pellegrini accumulated more T-Hg than O. niloticus. The T-Hg level was higher in the organs of both species during the rainy season than during the dry season in the following order: Gonads > Liver > Gills and exceeded the WHO/FAO recommended limit (T-Hg = 1.0 mg/kg wet weight) only in the testes and gills of L. pellegrini collected at the downstream sites of the Ulindi and Elila rivers. This does not necessarily reflect the level in the carcass. Taken together, the results suggest that mercury accumulated downstream of gold mining operations is altering the health of fish populations and that L. pellegrini can be considered a sentinel species for monitoring this pollution. To protect fish health, it is recommended that certain mining practices such as the misuse of mercury be avoided throughout the Congo River basi

ICDP workshop on the Lake Tanganyika Scientific Drilling Project: a late Miocene–present record of climate, rifting, and ecosystem evolution from the world's oldest tropical lake

The Neogene and Quaternary are characterized by enormous changes in global climate and environments, including global cooling and the establishment of northern high-latitude glaciers. These changes reshaped global ecosystems, including the emergence of tropical dry forests and savannahs that are found in Africa today, which in turn may have influenced the evolution of humans and their ancestors. However, despite decades of research we lack long, continuous, well-resolved records of tropical climate, ecosystem changes, and surface processes necessary to understand their interactions and influences on evolutionary processes. Lake Tanganyika, Africa, contains the most continuous, long continental climate record from the mid-Miocene (∼10 Ma) to the present anywhere in the tropics and has long been recognized as a top-priority site for scientific drilling. The lake is surrounded by the Miombo woodlands, part of the largest dry tropical biome on Earth. Lake Tanganyika also harbors incredibly diverse endemic biota and an entirely unexplored deep microbial biosphere, and it provides textbook examples of rift segmentation, fault behavior, and associated surface processes. To evaluate the interdisciplinary scientific opportunities that an ICDP drilling program at Lake Tanganyika could offer, more than 70 scientists representing 12 countries and a variety of scientific disciplines met in Dar es Salaam, Tanzania, in June 2019. The team developed key research objectives in basin evolution, source-to-sink sedimentology, organismal evolution, geomicrobiology, paleoclimatology, paleolimnology, terrestrial paleoecology, paleoanthropology, and geochronology to be addressed through scientific drilling on Lake Tanganyika. They also identified drilling targets and strategies, logistical challenges, and education and capacity building programs to be carried out through the project. Participants concluded that a drilling program at Lake Tanganyika would produce the first continuous Miocene–present record from the tropics, transforming our understanding of global environmental change, the environmental context of human origins in Africa, and providing a detailed window into the dynamics, tempo and mode of biological diversification and adaptive radiations.© Author(s) 2020. This open access article is distributed under the Creative Commons Attribution 4.0 License