This study examines the utility of morphology and DNA barcoding in species identification of freshwater fishes from north‐central Nigeria. We compared molecular data (mitochondrial cytochrome c oxidase subunit I (COI) sequences) of 136 de novo samples from 53 morphologically identified species alongside others in GenBank and BOLD databases. Using DNA sequence similarity‐based (≥97% cutoff) identification technique, 50 (94.30%) and 24 (45.30%) species were identified to species level using GenBank and BOLD databases, respectively. Furthermore, we identified cases of taxonomic problems in 26 (49.00%) morphologically identified species. There were also four (7.10%) cases of mismatch in DNA barcoding in which our query sequence in GenBank and BOLD showed a sequence match with different species names. Using DNA barcode reference data, we also identified four unknown fish samples collected from fishermen to species level. Our Neighbor‐joining (NJ) tree analysis recovers several intraspecific species clusters with strong bootstrap support (≥95%). Analysis uncovers two well‐supported lineages within Schilbe intermedius. The Bayesian phylogenetic analyses of Nigerian S. intermedius with others from GenBank recover four lineages. Evidence of genetic structuring is consistent with geographic regions of sub‐Saharan Africa. Thus, cryptic lineage diversity may illustrate species’ adaptive responses to local environmental conditions. Finally, our study underscores the importance of incorporating morphology and DNA barcoding in species identification. Although developing a complete DNA barcode reference library for Nigerian ichthyofauna will facilitate species identification and diversity studies, taxonomic revisions of DNA sequences submitted in databases alongside voucher specimens are necessary for a reliable taxonomic and diversity inventory.

Okpoka Creek of the Upper Bonny Estuary in the Niger Delta is a tidal creek receiving organic anthropogenic effluents from its environs. The study investigated the influence of tides (low and high) on the species composition, diversity, abundance, and distribution of phytoplankton. The surface water and phytoplankton samples were collected monthly from May 2004 to April 2006 at both tides from ten stations according to standard methods. Phytoplankton was identified microscopically. Species diversity was calculated using standard indices. Data analyses were done using analysis of variance, Duncan multiple range, and descriptive statistics. Phosphate and ammonia exceeded international acceptable levels of 0.10 mg/L for natural water bodies indicating high nutrient status, organic matter, and potential pollutants. A total of 158 species of phytoplankton were identified. Diatoms dominated the phytoplankton (62.9%). Diversity indices of diatoms were1.5±0.03(Margalef) and0.8±0.01(Shannon). Pollution-indicator species such asNavicula microcephala,Nitzschia sigma,Synedra ulna(diatoms),Cladophora glomerata(green alga),Euglena acus(euglenoid),Anabeana spiroides(blue-green alga), andCeratium furca(dinoflagellate) were recorded at either only low, high or both tides. Concerted environmental surveillance on Upper Bonny Estuary is advocated to reduce the inflow of pollutants from the Bonny Estuary into this Creek caused by tidal influence.

Information on the occurrence of pharmaceuticals in the environment of Nigeria is limited, only a single publication previously on pharmaceutical occurrence in the environment of Nigeria, which measured general estrogen levels in Enugu, South-East Nigeria. In order to establish a first overview, surface water samples from six locations as well as ten sewage sludge samples from waste water treatment plants were analysed for a range of different pharmaceuticals, including antibiotics, estrogens, and lipid-lowering drugs. The results of this monitoring campaign were evaluated in comparison to published measured environmental concentrations in Africa and worldwide. In surface water samples, 12 of 37 pharmaceutical substances were detected at concentrations ranging from Limits of Detection (LOD) up to 8.84 µg/l. Four of these pharmaceuticals were found at concentrations exceeding ecotoxicological predicted no-effect concentrations (PNEC). In industrial, domestic, and hospital sewage sludge, nine different pharmaceutical substances were detected with the NSAID diclofenac present in all samples at concentrations of up to 1100 µg/kg dry weight, exceeding the highest measured concentration of 560 µg/ kg reported in sludge samples worldwide. This study proves the presence of several pharmaceuticals at relevant concentrations in the environmental matrices studied. Further, more comprehensive monitoring campaigns, especially in locations with high population density and low dilution of treated or untreated waste water in receiving streams are recommended.

No abstract

The silver butter catfish (Schilbe intermedius) is widely distributed across African river systems. To date, information on its mitochondrial genetic diversity, population structure, and historical demography are not well-established. Herein, we combined newly generated mitochondrial cytochrome c oxidase (COI) subunit I gene sequences with previously published COI sequences in the global databases to reconstruct its phylogeography, population genetic structure, and historical demography. Results from the mtDNA phylogeography and species delimitation tests (Cluster algorithm-Species Identifier, Automatic Barcode Gap Discovery and Poison Tree Process model) revealed that S. intermedius comprises at least seven geographically defined matrilines. Although the overall haplotype diversity of S. intermedius was high (h = 0.90), results showed that East (Kenya) and West (Nigeria) African populations had low levels of haplotype diversity (h = ~0.40). In addition, population genetic polymorphism and historical demographics showed that S. intermedius populations in both East and West Africa underwent severe contractions as a result of biogeographic influences. The patterns of genetic diversity and population structure were consistent with adaptive responses to historical biogeographic factors and contemporary environmental variations across African river systems. This is suggestive of the influence of historical biogeographic factors and climatic conditions on population divergence of S. intermedius across African river systems. Given our discovery of previously