The non-Haplochromis fish fauna in Uganda: an update on the distribution and a review of data gaps.

Freshwater fishes are the second most threatened group of vertebrates after amphibians. In most developing countries, the conservation of freshwater fishes is largely hampered by limited information and data. The Red List assessments by the International Union for Conservation of Nature (IUCN) provide a benchmark for monitoring and mitigating species extinction risk, but these assessments require, inter alia, quantitative information on the species range in the wild. This information is largely missing for many species that face extinction threats. Here, we combine species occurrence data, expert knowledge, and literature to (i) review and update the distribution of non-Haplochromis fish species native to Uganda and (ii) determine the national geographical range of these fish species relative to their global range. For the latter, we use the IUCN's standard protocol for mapping distribution of freshwater species from which we derive both the national and global extent of occurrence (EOO) and area of occupancy (AOO). We show that at least 110 non-Haplochromis species occur in Uganda, with the majority species having a wide distribution outside the national boundaries. However, substantial gaps exist in data on presence of the species in their native range, where more than 60% of the species are designated as "possibly extant." We elaborate on fish species previously believed to occur in Uganda, e.g., Amphilius kivuensis Pellegrin, 1933; Bagrus degeni Boulenger, 1906; Marcusenius macrolepidotus (Peters, 1852); Petrocephalus catostoma (Günther, 1866); and Lacustricola pumilus (Boulenger, 1906), but where recent studies suggest they lack a native distribution within the country. In addition, we highlight fishes with occurrence records that site them in areas beyond their previously known range, requiring further investigations to ascertain their present status. This work has potential to (i) trigger evidence-driven policies aimed at site-based conservation and rethinking of extent of protected areas, (ii) stimulate data collection, especially in areas where fishes are designated as "possibly extant" and "presence uncertain," and (iii) aid the IUCN Red List assessments, for which conservation status of the majority non-Haplochromis species is outdated and many others remain unevaluated due to lack of quantitative information on their range.

Using sediment fingerprinting to identify erosion hotspots in a sub-catchment of Lake Kivu, Rwanda.

Sedimentation of water bodies affects water quality and biotic communities of aquatic ecosystems. Understanding the causes and origin of sediments is crucial for planning watershed management activities and safeguarding aquatic biodiversity and critical ecosystem services. Rwanda, as a hilly country, experiences increased sedimentation due to unsustainable land use practices in upstream catchment areas which negatively affects irrigation, fishing and hydropower generation. We used a sediment fingerprinting technique to determine sources of sedimentation and identifying hotspots of soil erosion in Sebeya River Catchment (area of 357 km2), a sub-catchment of Lake Kivu located in Northwest Rwanda. Five soil samples were collected from each of the six geological classes, and 34 suspended sediment samples were taken within key locations of the hydrological network in the catchment. X-Ray Spectrometry was used to determine the geochemical composition of suspended sediments and soil. A multi-step statistical procedure with a Bayesian mixing model was used to determine the contribution of each geologic group and sub-catchment to the suspended sediments in the river. Erosion hotspots were classified based on the underlying land use and their contribution to the suspended sediments. The resulting erosion hotspot map shows that about 70.9% of the Sebeya Catchment area contributes at least 50% of sediment load in the river and currently experiences unsustainable land use and land cover. The erosion hotspots identified and culpable factors should be used to guide best land use practices, prioritizing the areas with high contribution to the river sedimentation in Sebeya Catchment.

A novel index to aid in prioritizing habitats for site-based conservation.

Funding biodiversity conservation strategies are usually minimal, thus prioritizing habitats at high risk should be conducted. We developed and tested a conservation priority index (CPI) that ranks habitats to aid in prioritizing them for conservation. We tested the index using 1897 fish species from 273 African inland lakes and 34 countries. In the index, lake surface area, rarity, and their International Union for Conservation of Nature (IUCN) Red List status were incorporated. We retrieved data from the Global Biodiversity Information Facility (GBIF) and IUCN data repositories. Lake Nyasa had the highest species richness (424), followed by Tanganyika (391), Nokoué (246), Victoria (216), and Ahémé (216). However, lakes Otjikoto and Giunas had the highest CPI of 137.2 and 52.1, respectively. Lakes were grouped into high priority (CPI > 0.5; n = 56) and low priority (CPI < 0.5; n = 217). The median surface area between priority classes was significantly different (W = 11,768, p < .05, effect size = 0.65). Prediction accuracy of Random Forest (RF) and eXtreme Gradient Boosting (XGBoost) for priority classes were 0.912 and 0.954, respectively. Both models exhibited lake surface area as the variable with the highest importance. CPI generally increased with a decrease in lake surface area. This was attributed to less ecological substitutability and higher exposure levels of anthropogenic stressors such as pollution to a species in smaller lakes. Also, the highest species richness per unit area was recorded for high-priority lakes. Thus, smaller habitats or lakes may be prioritized for conservation although larger waterbodies or habitats should not be ignored. The index can be customized to local, regional, and international scales as well as marine and terrestrial habitats.

High-resolution bathymetries and shorelines for the Great Lakes of the White Nile basin.

HRBS-GLWNB 2020 presents the first open-source and high-resolution bathymetry, shoreline, and water level data for Lakes Victoria, Albert, Edward, and George in East Africa. For each Lake, these data have three primary products collected for this project. The bathymetric datasets were created from approximately 18 million acoustic soundings. Over 8,200 km of shorelines are delineated across the three lakes from high-resolution satellite systems and uncrewed aerial vehicles. Finally, these data are tied together by creating lake surface elevation models collected from GPS and altimeter measures. The data repository includes additional derived products, including surface areas, water volumes, shoreline lengths, lake elevation levels, and geodetic information. These data can be used to make allocation decisions regarding the freshwater resources within Africa, manage food resources on which many tens of millions of people rely, and help preserve the region's endemic biodiversity. Finally, as these data are tied to globally consistent geodetic models, they can be used in future global and regional climate change models.