Update of ichthyofauna diversity and ecological status of a coastal River Nero (Côte d’Ivoire – West Africa)

Abstract

The general aim of this study is to update the inventory of the fish species and to specify distribution patterns in the Nero River ichthyofauna in order to establish some basis for the conservation of these fish communities and their habitat. From February 2009 to January 2010, thirty-three sites were sampled monthly with gill nets and a backpack electrofisher, and environmental variables were recorded. Overall, 46 species included in 33 genuses, 24 families and 9 orders were collected. Eleven families and 30 species were the first records for the Nero River. Including all species previously listed in the literature, the number of species presently known in the Nero River and its tributaries is revised to 59. Four families, Alestidae (21%), Schilbeidae (19%), Cyprinidae (17%) and Cichlidae (16%) that made up 73% of the total number of the catches, were the most dominant. The most dominant numerical species were Schilbe mandibularis and Brycinus longipinnis. Fish species and sampling sites along with eight environmental variables were ordinated with canonical correspondence analysis (CCA) coupled to the Monte Carlo test. Ecological status based on fish assemblage according to environmental variables and anthropogenic pressures showed that miss dead wood leaves and roots, electrical conductivity, total dissolved solids, mud, nitrite, basin width, dissolved oxygen and pH, were the primary factors influencing fish distribution. The environmental tolerance index (ETI), ecological tolerance (tk ) and optima (uk ) values of 10 species to 8 different environmental variables were analyzed. Six species (Hemichromis fasciatus, Epiplatys chaperi, Barbus ablabes, B. longipinnis, Hemichromis bimaculatus and Chromidotilapia guntheri) have high ETI and a cosmopolitan distribution in the Nero River. In the tributaries of the middle course, high concentrations of nitrite in the water, added to the presence of a lot of tolerant species in the ichthyofauna are indications of disturbance of these areas. Subsequent recommendations were formulated for efficient restoration and conservation management of this River.

Fish diversity and heavy metal accumulation of Pb, Cu and Zn after Mount Sinabung Eruption in Benuken River, North Sumatra, Indonesia

“…Ecologically, it is assumed that high species diversity indicated a better ecosystem balance, while poor diversity indicated that the water is being polluted or stressed by some stressors, for example, natural disasters. The ecological status based on fish assemblage according to environmental variables and anthropogenic pressures showed that total dissolved solids, nitrite, dissolved oxygen, pH, were the primary factors influencing fish distribution (N'Zi et al 2015). In this study, Tor soro is the dominating fish species in the Benuken River.…”

Fish assemblages in the Upper part of the Volta River, Burkina Faso: A link analysis towards fisheries management and conservation

“…Some of these poorly represented species are also rare in other rivers of the Nilo-Sudanian ichthyological province, while some other species from the group are considered to be well represented. From this group, Brycinus longipinnis represented more than 20% of fish individuals recorded in upper and middle course of River Nero in Côte d"Ivoire (N"Zi et al, 2015). Fish families such as Anabantidae, Arapanidae, Bagridae, Citharinidae, Distichodontidae, Gymnarchidae, Latidae, Malapteruridae, Polypteridae and Protopteridae were rare in the catch.…”

Association of riverine prawns and intermediate host snails and correlation with human schistosomiasis in two river systems in south-eastern Côte d'Ivoire

“…We employed an electric fishing device powered by a 12 V and 24 A rechargeable battery (Rundumfisch AG; Altendorf, Switzerland). The generator delivers either direct current or an alternating current between two electrodes (N'Zi et al ., 2015). Each electroshock collection lasted 15 min.…”