African Freshwater Research Articles

Plastics underground: microplastic pollution in South African freshwater caves and associated biota

Abstract Microplastics (MPs) have been characterised in South African rivers, lakes, and the marine environment, yet we know less about MPs in subterranean environments. In this study, we assessed MP pollution in the sediment, subsurface water, and resident freshwater amphipod, Sternophysinx species across six South African subterranean cave systems. We hypothesised that MP pollution will increase with human visitations and activities in and around selected subterranean caves. We found MPs in sediments, subsurface waters, and amphipod species ranging from 4.9 ± 1.2 to 25.0 ± 6.9 particles/kg–1, 2.7 ± 0.7 to 15.0 ± 1.7 particles/L–1 and 2.1 ± 0 to 9.8 ± 3.1 particles/dry mass, respectively, with polypropylene being the most abundant polymer according to FTIR analysis. White fibres were dominant in sediments and water samples, whereas blue fibres were dominant in amphipods. Our results supported the hypothesis that MPs densities were correlated with human visitation and activities in and around the caves. The presence of MPs in subterranean caves presents a biodiversity and conservation threat to endemic and understudied cave-dwelling aquatic invertebrates, due to MPs ability to be transferable between trophic levels causing physiological constraints.

Catfishes from the North-Western Part of Lake Tanganyika: Contribution to a Reference Library of DNA Barcodes

In spite of the global barcoding effort, there is still a lack of genetic data on African freshwater fishes. We aimed to contribute to bridging this gap by providing molecular data on commercially important catfish species from the north-western part of Lake Tanganyika. We collected 215 catfish specimens and sequenced the standard vertebrate barcoding gene (COI) for 41 specimens. Additionally, we sequenced 20 specimens for the mitochondrial Cyt-b gene to make the link to previously published datasets. We identified 11 species using morphology, compared DNA sequences with those available on GenBank, and employed Automatic Barcode Gap Discovery (ABGD) and phylogenetic approaches. The dataset includes the first molecular data (COI and Cyt-b) for Chrysichthys acsiorum, as well as the first-ever COI sequences for Dinotopterus cunningtoni and Malapterurus tanganyikaensis. Our findings extend the known distribution of C. acsiorum by approximately 100 km. Additionally, we demonstrated the difficulty in delineating species of Chrysichthys and Synodontis from Lake Tanganyika with molecular tools. For Chrysichthys, automated methods, such as ABGD, failed to delineate species. However, barcoding does seem promising as all the individual species are resolved as clades. Within Synodontis, the study found a strong similarity between S. grandiops and S. multipunctatus, highlighting a need for revision. Our findings emphasize the necessity for integrative taxonomy in the study of catfishes from Lake Tanganyika.

Levels and Classification of Microplastics and Their Impact on the Wellbeing of Selected Commercially Important Fish Species in Kisumu Bay, Lake Victoria.

Microplastics (MPs) are emerging pollutants of concern in aquatic ecosystems. Fish ingest MPs accidentally during normal feeding because they resemble prey or by ingesting prey that previously consumed them. Despite severe plastic pollution in Africa, some countries, including Kenya have implemented laws to curb this pollution menace. MPs have scantly been studied in African freshwaters. This study provides empirical data and describes the levels of MPs in four commercially important fish species in Lake Victoria. A total of 95 fish samples were collected from four sampling sites (inshore-offshore waters) between March and May 2022. Microscopy and Attenuated Total Reflectance Fourier Transformed Infrared (ATR-FTIR) spectroscopy methods were used to identify MPs. In this study, 62 out of 95 (65.26%) of the gastrointestinal tracts of the sampled fish contained MPs. The four species showed different proportions of detected MPs among the sampled individuals: 75.00% (Clarias gariepinus), 75.00% (Synodontis victoriae), 71.43% (Lates niloticus), and 59.26% (Oreochromis niloticus). Polystyrene (PS) and poly (perfluorobutadiene) were the main plastic polymers in the fish samples. The condition factors estimated for O. niloticus, S. victoriae, and L. niloticus were > 1 and < 1 for C. gariepinus, respectively. Positive correlations were observed between microplastic numbers and fish length and microplastic numbers and fish weight. However, the low R2 values obtained implied no strong relationship exists between these parameters. These findings provide evidence of microplastic contamination in fish in Kisumu Bay.

Extracts of southern African aquatic and wetland plant species as effective tyrosinase inhibitors

South Africa harvests approximately 19 500 tonnes of medicinal plants annually for the treatment of various ailments and an additional 6000 tonnes is exported globally for the development and design of cosmetic and medicinal products. South Africa is home to 30 freshwater and marine ecological regions, however, medicinal plant species from these semi-aquatic and aquatic habitats are largely understudied in comparison to other biomes. The lack of knowledge and reported pharmacological activity of these species may be hindering the potential contribution to the herbal medicine and personal care markets. South Africa is Africa's largest market for cosmetic and personal care products and in 2018 this sector reported 3.2 billion US dollars in revenue. Eighteen (18) Southern African freshwater aquatic and wetland plant species were selected and screened for their potential as cosmeceutical ingredients by investigating their antibacterial, anti-tyrosinase and cytotoxicity. The extracts of Erythrina zeyheri and Plantago longissima exhibited antimycobaterial activity with MIC values of 125 µg/mL. Two extracts of the genus Cyperus, C. marginatus and C. sexangularis showed tyrosinase inhibition with IC50 values of 75.03 and 64.26 µg/mL, respectively. Carex rhodesiaca and Gunnera perpensa both exhibited dual antimicrobial activity against Cutibacterium acnes with MIC values of 250 and 125 µg/mL, respectively and anti-tyrosinase activity with IC50 values of 64.71 and 70.43 µg/mL. Persicaria senegalensis exhibited anti-tyrosinase activity with an IC50 of 71.59 µg/mL. Fractionation of P. senegalensis yielded F14 with an IC50 of 68.77 µg/mL against tyrosinase enzyme activity. Purification of F3 yielded (24S)-Stigmast-5,22(E)-dien-3-β-ol which is the first report of this compound from this species. This study provides scientific validation of the traditional use of the selected species and provides proof of concept for further investigations of these extracts as potential active ingredients in the personal care sector.

Ecological speciation in East African freshwater crabs of the genus Arcopotamonautes Bott, 1955 across a lake-river boundary in the Lake Malawi catchment (Potamoidea: Potamonautidae: Potamonatinae)

Abstract Geological, climate and ecosystem changes in Africa likely influenced speciation of Afrotropical freshwater crabs. In total, the subfamily Potamonautinae comprises over 120 species, and this diversity provides a valuable opportunity to explore speciation processes. Here we study diversification of potamonautid crabs in the Lake Malawi catchment, and investigate whether speciation has taken place across a lake-river boundary. Specifically, we reconstruct evolutionary relationships of the Malawi blue crab, Arcopotamonautes orbitospinus (Cunnington, 1907), an endemic of Lake Malawi, and of A. montivagus (Chace, 1953) from rivers and streams draining into Lake Malawi, and smaller lakes within this catchment. Our phylogenetic analysis of over 28,000 single nucleotide polymorphisms shows a monophyletic A. orbitospinus nested within a clade otherwise comprised of A. montivagus from across the Lake Malawi catchment (A. montivagus Group I). We also identified a second allopatric clade of A. montivagus from the Rungwe mountains of Tanzania, and neighbouring Zambia (A. montivagus Group II). Morphological differences were apparent between all three groups. Collectively these results show A. montivagus is a paraphyletic riverine taxon that has diversified in allopatry, and that this species entered Lake Malawi and seeded the specialised heavily armoured lacustrine species, A. orbitospinus. We hypothesise that formation of deep-water conditions within Lake Malawi, together with differences in predation pressures between the rivers and lake, provided ecological opportunities for natural selection to drive speciation across the lake-river boundary. We conclude that geographical separation and ecological adaptation are potentially important drivers of evolutionary diversification in these enigmatic freshwater crabs.

Generalist species exhibit more genetic structure in comparison to a habitat specialist: Evidence from a phylogeographic study of two freshwater crabs (Decapoda: Potamonautidae: Potamonautes), implications for habitat conservation.

During the present study, the phylogeography of the wetland specialist, freshwater crab, Potamonautes flavusjo, was investigated and compared to that of the ubiquitous, generalist, P. sidneyi, using DNA sequence data from the mitochondrial cytochrome oxidase subunit one (COI). We inferred the evolutionary history of each species and compared their population-level genetic structure by constructing haplotype networks and using an analysis of molecular variation. Additionally, we explored the evolutionary relationship between southern African lentic and lotic freshwater crab species by examining the usefulness of carapace attributes in relation to genetic indices and a species' assumed dispersal capacity. In the lentic species, P. flavusjo, a single interconnected haplocluster characterized by shared haplotypes was observed, suggesting marked maternal dispersal, a result corroborated by the low F ST values. In contrast, for the lotic species, P. sidneyi two distinct haploclusters and marked genetic differentiation was observed indicating the absence of maternal dispersal, a result corroborated by the high F ST values. The phylogenetic relationship in P. sidneyi was further investigated using a maximum likelihood and Bayesian inference analyses with the addition of sequence data from the mitochondrial 16S rRNA locus to estimate divergence times. Three species delimitation methods (ASAP, PTP, and bGMYC) were used to explore the presence of distinct lineages in P. sidneyi. The phylogenetic results indicated that within P. sidneyi two clades were present, while divergence time estimates suggest cladogenesis during the middle to late Pleistocene. The species delimitation methods used showed moderate congruence, however all oversplit the number of putative lineages. Our results indicated that P. sidneyi is a species complex comprised of two cryptic lineages, occurring in sympatry contemporarily possibly alluding to secondary contact. Carapace height was found to have no discernible influence on the genetic indices and presumed dispersal capabilities of mainland southern African freshwater crab species. The importance of our results are discussed in terms of conservation of freshwater habitats.

Acute toxicity of rich triethylene glycol on juvenile African freshwater catfish (Clarias gariepinus) around a natural gas dehydration facility

Triethylene glycol (TEG) removes equilibrium water from natural gas but may spill during equipment maintenance and other poor safety practices. Studies on the toxicity of rich TEG in aquatic habitats are scarce. In this study, the toxicity of rich TEG on freshwater juvenile African catfish (Clarias gariepinus) test organism was conducted. The experimental design for the toxicity tests was 3 × 5 × 6 factor in a randomized complete block design, with six levels of treatment, observed at five intervals and in three replicates. The acute toxicity was carried out by exposing them to various lethal concentrations of the Rich TEG in solution. Physicochemical parameters, including temperature, dissolved oxygen, pH, conductivity, and total dissolved solids, were measured and recorded for five test concentrations of 25.92, 12.96, 6.48, 3.24, 1.62, and 0.0 ml/l (control). The concentration responses for the fish mortality at 24, 48, 72, and 96 h were also derived. No mortality was observed between Rich TEG concentrations of 0 ml/l to 25.92 ml/l after 72 h of exposure. However, some mortality was observed between 1.62 ml/l to 25.92 ml/l after 96 h of exposure. The highest concentration of 25.92 ml/l recorded a higher mortality of 6.0 ± 0.4, which is an average of 60%, while the lowest mortality was recorded in the control (0 ml/l), at an average of 0% mortality rate. The results underscore the concentration-dependent effects of rich TEG on the test organism, highlighting the need for targeted attention to higher concentration levels.

First record of the fountain bladder snail Physa fontinalis (Linnaeus, 1758) (Gastropoda: Hygrophila) in Morocco

Alien and invasive species pose a significant threat to global biodiversity, causing costly economic and environmental damage. Recent field surveys in northern Morocco have led to the discovery of the fountain bladder snail Physa fontinalis (Linnaeus, 1758), providing the first evidence of its occurrence in North Africa. The exotic species is currently only known from one locality in Morocco, future surveys may reveal its presence elsewhere. It is essential to monitor its spread within invaded areas and conduct studies to improve our understanding of its biology, ecology, and potential impact on native communities in North African freshwaters.

Optimizing waterborne eDNA capture from waterholes in savanna systems under remote field conditions.

Environmental DNA (eDNA) is used for biodiversity assessments in a variety of ecosystems across the globe, whereby different eDNA concentration, preservation and extraction methods can outperform others depending on the sampling conditions and environment. Tropical and subtropical ecosystems in Africa are among the less studied systems concerning eDNA-based monitoring. Waterholes in arid parts of southern Africa represent important agglomeration points for terrestrial mammals, and the eDNA shed into such waterbodies provides a powerful source of information for monitoring mammalian biodiversity in the surrounding area. However, the applied methods for eDNA sampling, preservation and filtering in different freshwater systems vary greatly, and rigorous protocol testing in African freshwater systems is still lacking. This study represents the first attempt to examine variations in eDNA concentration, preservation and extraction methods under remote field conditions using waterborne eDNA in a savanna system. Collected samples were heavily affected by microalgal and bacterial growth, impeding eDNA capture and PCR success. We demonstrate clear effects of the methodological choices, which also depend on the state of eDNA. A preliminary metabarcoding run showed little taxonomic overlap in mammal species detection between two metabarcoding primers tested. We recommend water filtering (using filters with pore sizes >1 μm) over centrifugation for eDNA concentration, Longmire's solution for ambient temperature sample preservation and Qiagen's DNeasy PowerSoil Pro Kit for DNA extraction of these inhibitor-prone samples. Furthermore, at least two independent metabarcoding markers should be utilized in order to maximize species detections in metabarcoding studies.

Microplastic Abundance and Sources in Surface Water Samples of the Vaal River, South Africa

Microplastics (MPs) have emerged as a global environmental concern due to their persistent nature. In South Africa, microplastic research has primarily focused on marine systems. However, recent years have seen a shift in focus to studying MPs in South African freshwaters. In this study, MPs with a minimum size of 0.055 mm in surface water of the Vaal River, South Africa, were reported. MPs were 100% prevalent, with a mean numerical abundance of 0.68 ± 0.64 particles/m3. Small-sized MPs of < 1 mm accounted for the largest proportion. MPs were chemically identified as high-density polyethylene, low-density polyethylene, and polypropylene according to their Raman spectra. The prevalence of fragments (41.6%) and fibers (38.5%) over pellets (8.1%) indicates that microplastics are from secondary sources. The prevalence of polyethylene and polypropylene is consistent with microplastics being from secondary sources. These polymers are commonly used in single-use plastics, packing bags, textiles, and containers. These characteristics are of great concern due to their implications on the bioavailability and toxicological impacts of MPs. Consequently, these properties may pose more hazards to aquatic biota inhabiting the Vaal River.

Characterizing anthropogenic litter pollutants in African freshwater ecosystems: A case study of Dunga Beach in Lake Victoria, Kenya

AbstractAnthropogenic litter (AL) in world's aquatic ecosystems presents critical ecological threats to environmental quality, aquatic biodiversity and human welfare. However, most studies on AL have been conducted in marine ecosystems with very little focus being given to freshwater systems like Lake Victoria. This study characterized AL pollutants in Dunga beach in Lake Victoria, Kenya, where sampling was done in the beach, riparian and benthic zones along a 100 m reach for 6 days. Across the sampled reaches, the AL associated with packaging, consumer products, building and construction, transport, electronic wastes, textile, fishery and medical materials were collected, counted, sun‐dried and weighed. AL were more abundant in the beach and riparian zone than in the benthic reaches with plastics being the dominant litter in all reaches. Based on Kruskal–Wallis rank sum test the density of AL associated with packaging and consumer products was significantly higher than other AL in all the reaches. Plastics, polystyrene and glass wastes dominated the beach zone at 31.19%, 12.14% and 11.14%, respectively. In the benthic area, the dominant wastes were plastics, fishery and polystyrene items at 22.14%, 16.34% and 12.14%, respectively. The top 10 AL pollutants in Dunga beach were as follows: bags/food wrappers, bottle caps, diapers, plastic and glass beverage bottles, plastic plates, forks, knives, spoons, straws and e‐wastes. Based on data from literature, several clear patterns emerged when comparing relative AL abundance across other aquatic habitats. In the Lake Michigan Beach, the AL were dominated by plastics (41.2%) followed by cigarettes at 29.3%. In contrast, Chicago River Beach contained more glass wastes (42.1%) while Chicago River Riparian had more plastics (57.8%). At the South Sea of Korea, fishing gear wastes were the majority AL (61.1%). AL consisting of fishing items was restricted to benthic and riparian settings, in which the benthic zone had the most items recorded. It is therefore evident that a large amount of AL waste accumulates at Dunga, Hippo point and other beaches in the world, thus justifying the need for beach cleaning and maintenance strategies. This study presents baseline data that is useful to environmental ecologists, aquatic scientists and management authorities to formulate policies, evaluate guidelines and recommend beach management strategies to conserve aquatic biodiversity, human health and aesthetic value of the freshwater habitats.

Comparative lipid composition and GC–MS fatty acid profiling of tropical African freshwater fishes

In dietary contexts, fish are renowned for the diverse array of unsaturated fatty acids they provide to the body. While data regarding the fatty acid composition of freshwater fish are readily available in most developed countries, research on African freshwater fish remains notably limited. In this study, we investigated the fatty acid composition of fifteen freshwater fish species from Africa, primarily Afrotropical regions. Lipids were extracted using a solvent mixture of methanol, water, and chloroform. Subsequently, total fatty acids were determined by saponification, and the fatty acid profile was analyzed via GC–MS following methylation in the presence of BF3 and methanol. The results revealed lipid levels in fish fillets ranging from 1.99 % for T. guineensis to 6.41 % for M. bananensis. Total fatty acid percentages of lipids were found to be 81.40 ± 9.15 % for S. nigripinnis, 83.75 ± 6.12 % for L. niloticus, and 92.99 ± 11.30 % for C. dageti. The fatty acid profiles of 15 properly identified fish species have been determined, with the majority being identified for the first time. The composition of health-important omega-3 fatty acids EPA and total DHA ranged from 4.82 ± 0.2 % for Cyprinus lepidotus to 17.43 ± 2.50 % for Mugil bananensis. Unsupervised multivariate data analysis of fatty acid profiles of the different fish species showed significant differences. When the fish were grouped into 4 categories based on their similarities, 12 discriminant fatty acids characteristic of each group were identified. Among these fatty acids are omega-6 acids such as γ-linolenic acid and arachidonic acid, and omega-3 7,10,13,16,19-docosapentaenoic acid (DPA). This research opens avenues for consumers to make informed dietary choices aligned with their specific fatty acid needs and preferences regarding fish consumption.

The first evidence of microplastic presence in the River Nile in Khartoum, Sudan: Using Nile Tilapia fish as a bio-indicator

The extent of microplastics in African freshwater systems remains less investigated. In Sudan, there is no single study reporting microplastics in water bodies. This scoping study aimed to investigate the presence and characteristics of microplastics (MPs) in Nile Tilapia fish from the River Nile in Khartoum, Sudan. The digestive tracts of the fish were digested using 10% potassium hydroxide, and microplastic particles were extracted by density separation using sodium iodide. 567 particles of different sizes (0.04–4.94 mm), shapes (fibers, fragments, films, foams, and pellets), and colours (mostly green, black, blue, and grey) were identified as microplastics. The average abundance of microplastics was 72.02 ± 62.06 particles/kg, and the average intensity was 18.90 ± 9.17 MPs/fish. Small-sized (<1 mm), fibrous-shaped, and coloured microplastics were most abundant in all samples, representing 56%, 85%, and 84%, respectively. Surface examination by SEM showed signs of fragmentation such as cracks, pits, and pores. Two polymer types (high-density polyethylene and polypropylene) were identified by Raman spectroscopy. The predominance of fibers and fragments (94.5%) over pellets (0.35%) and the apparent signs of fragmentation may indicate that MPs are mostly secondary MPs. Wastewater effluent, domestic discharge, and recreational activities are the potential sources. This scoping investigation provided the first data on microplastic presence in the River Nile in Khartoum, and it could be used to guide future studies to fill research gaps in the region.

The status of COI and 12S rRNA DNA barcode reference libraries for freshwater fish in South Africa: Implications for future eDNA projects

Environmental DNA metabarcoding (eDNA) is a rapidly emerging field in which high-throughput sequencing is used to catalogue the biodiversity of ecosystems through the amplification of DNA extracted from environmental samples (water, air, faeces and soil). Although eDNA has strong links to DNA barcoding, the molecular marker most often used to detect vertebrates in eDNA studies is a portion of the mitochondrial 12S ribosomal RNA (12S rRNA) and not the standard cytochrome oxidase I (COI) marker used in traditional DNA barcoding. eDNA methods rely on a comprehensive reference library to link sequence data to species, which are often lacking in hyper-diverse countries such as South Africa. In this study, we review the present state of DNA barcode reference databases for both 12S rRNA and COI for freshwater fish (native and introduced) found in South African aquatic systems. Analysis of DNA records available on GenBank and the Barcode of Life Database (BOLD) revealed incomplete records of the examined taxa for both markers. Our findings showed that 34 species, 6 genera and 0 families of native South African freshwater fish lack COI barcode records, while 86 species, 22 genera and 8 families lack 12S rRNA records. Unlike the native freshwater fish, the non-native fish all had barcode records available for both COI and 12S rRNA. Producing comprehensive reference libraries for both markers is an important first step in developing an eDNA protocol for the non-invasive monitoring of native and non-native freshwater fish in South Africa.

Future success and ways forward for scientific approaches on the African Great Lakes

The seven African Great Lakes are some of the most critical freshwater, large-lake systems in the world, providing essential services, food, drinking water, and other livelihood support to over 62 million people. Like most freshwater systems around the world, these lakes are strained by anthropogenic stressors, leading to degradation of these biologically important, and human-dependent resources. Despite their importance, these lakes suffer from insufficient research approaches which are short-term, disparate, and unharmonized. Further, a lack of monitoring, data and information exchange, education and training, and gender balance in research, all lead to insufficient knowledge on which to better manage and protect these lakes. While past efforts have resulted in some knowledge accumulation, there is a need for new approaches to understanding and managing these lakes: bottom-up, harmonized, and long-term processes. This paper, and those within this special section of the Journal of Great Lakes Research, highlight new, highly collaborative efforts of freshwater experts representing each riparian country of each African Great Lake through formal advisory groups. These papers are the result of harmonized efforts and collegial agreements as to what issues need to be addressed foremost, written by those on the ground. While each lake has specific, prioritized lists of issues, five overarching issues must be addressed to achieve success on these lakes: providing agency and coordination of African freshwater scientists; increase long-term monitoring; strengthen education and training of existing and future experts; enhance information and data exchange; and ensure stronger gender balance in science and leadership positions.

Comparative Morphology of the Digestive Tract of African Bush Fish (Ctenopoma acutirostre) and Paradise Fish (Macropodus opercularis) Inhabiting Asian and African Freshwaters.

Anabantidae is a large and diverse group of fish cultured both under aquaculture conditions and as a hobby. These fish share a common structural feature in the form of an additional respiratory organ. Despite the enormous availability of these fish worldwide, little is known about their feeding preferences in husbandry and their influence on homeostasis under both industrial and domestic conditions. This study describes, for the first time, the structure of the digestive tracts of two Anabantoidei fishes: African bush fish (Ctenopoma acutirostre) and paradise fish (Macropodus opercularis). The overall structure of the digestive tract and its histological structure were analyzed and compared in both fish species. Physiological predispositions indicated a predominance of omnivorous fish traits in M. opercularis in contrast to C. acutirostre, which has several morphological traits indicating greater adaptation to carnivory, particularly ichthyophagy. The results obtained will allow further research to be conducted in the future to optimize the nutrition and feeding of these fish and to develop appropriate dietary recommendations.

A stable isotope analysis of the dietary patterns of the aquatic apex predator, the African tigerfish (Hydrocynus vittatus).

Stable isotope analyses, specifically δ13 C and δ15 N, are useful tools increasingly used to understand ecosystem function, food web structures and consumer diets. Although the iconic tigerfish, Hydrocynus vittatus, is regarded as an apex predator in southern African freshwater systems, little information is available regarding their feeding behaviour and how this may change with growth or differ between ecosystems with most information stemming from stomach content analyses (SCA). The aim of the present study was to address this lack of information through a baseline study of the diet of large and small tigerfish in various lentic and lotic ecosystems in South Africa using stable isotope methods. Fish and various food web components and food sources were collected from two river and two lake ecosystems from the Lower Phongolo River floodplain, SA. The δ13 C and δ15 N values for all samples were determined and multivariate analyses and Bayesian analytical techniques applied to determine the feeding ecology of H. vittatus and how this may differ with size and habitat type. Analyses revealed a substantial difference in the type and abundance of food sources contributing to the diet of H. vittatus between ecosystems, most prominently between the lotic systems, where less dietary specialisation was observed, and lentic systems where more specialisation was observed. Furthermore, there was a distinct difference in diet between small and large tigerfish, especially in the lotic system, indicating an ontogenetic diet shift as tigerfish grow and further supporting previous SCA studies. This is the first study of its kind on the African continent for H. vittatus and the findings illustrate the value of stable isotope analysis in providing in-depth information into the feeding ecology of consumers and how this may differ between size classes and habitat types. This article is protected by copyright. All rights reserved.

Opportunistic feeding habits of two African freshwater clupeid fishes: DNA metabarcoding unravels spatial differences in diet and microbiome, and identifies new prey taxa

Opportunistic feeding habits of two African freshwater clupeid fishes: DNA metabarcoding unravels spatial differences in diet and microbiome, and identifies new prey taxa

Correction to: A review of the production status, constraints, and opportunities in East African freshwater capture and culture fisheries

Correction to: A review of the production status, constraints, and opportunities in East African freshwater capture and culture fisheries

Description of two new species of Central African freshwater crabs from the Democratic Republic of the Congo and Rwanda (Brachyura: Potamoidea: Potamonautidae).

This work focuses on two species of freshwater crabs from Central Africa: Longipotamonautes bolobo n. sp. (from the Democratic Republic of the Congo), and Rotundopotamonautes rwanda n. sp. (from Rwanda). These two taxa are described based on newly identified museum material. Diagnoses, illustrations, and a distribution map are provided for these species, and their conservation status is discussed.