Fish composition and structure along longitudinal gradient of a coastal river (Ehania River; south-east of Ivory Coast) (original) (raw)
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Iranian Journal of Fisheries Sciences
Fish assemblage was investigated during the study of longitudinal profile of the Ehania River Basin in southeastern Côte d'Ivoire. This area is subjected to intense human activities with many plantations (palm tree, banana, pineapple, coffee, rubber and cocoa). Samples were collected, with gillnets of different mesh sizes, through 6 sampling surveys during dry and rainy seasons from February 2010 to December 2010 at 6 sampling sites. A total of 70 fish species belonging to 48 genera, 28 families and 10 orders were recorded. The temporal variation of diversity index is less marked than spatial variation. The upstream, with 35 species, was less rich in species than the medium area and downstream areas (respectively 46 and 68). The upstream and downstream areas gathered 35 species. Thirty three species were common to the upper and middle areas and 46 species appeared both in the lower courses and the middle area. The 21 species restricted to the lower part of the river are mainly estuarine/marine origin. The beta diversity value revealed low similarity between the lower and upper course of Ehania River. The lowest values of Shannon's diversity index and equitability index were observed in the middle part of the River which characterized by high population density and intense agricultural activity with many plantations.
Ribarstvo, 2010
Fish assemblage patterns in Taabo Reservoir, a hydroelectric lake of Ivory Coast, were studied and related to the longitudinal gradient (river-dam gradient) composed of riverine, transitional, and lacustrine zones. Data were collected at 5 stations and each one was sampled during 5 surveys. Fish community structure was analysed using alpha and beta diversity indices. In total, 53 fish species were obtained in the whole ecosystem. Total species richness recorded at each ecological zone was 42, 43 and 45 species respectively in the riverine, transitional and lacustrine zones. Alpha diversity did not differed significantly along the longitudinal gradient but reached the highest value (33 species) in the transitional zone and the lowest (18 species) occurred in both the riverine and lacustrine zones. Temporal variability of Alpha diversity according to the hydrological regime of the lake differed with the zone. Beta diversity showed that fish assemblages similarity was higher between the transitional and the riverine zones (â w = 0.43) and lower between the riverine and the lacustrine zones (â w = 0.79).
European Scientific Journal, 2015
The inventory and distribution of fish assemblages of Bandama River were studied from October 2008 to September 2009. Fish samples were collected in three areas (upper, middle and lower catchment) using a back pack electrofisher and two batteries of gill-nets with mesh sizes between 8 and 80 mm. A total of 64 sites were visited and 83 fish species belonging to 11 orders, 30 families and 51 genera were identified. We counted 13 marine and/or brackish-water species and 70 freshwater species. Among them, two introduced species (Heterotis niloticus and Oreochromis niloticus) and one hybrid form (Tilapia zillii x T. guineensis) were found. Characiformes order, mainly represented by Alestidae family and Brycinus longipinnis species, are the most abundant. Studies comparing biodiversity of families used species richness and abundance, showed that families of Cichlidae and Cyprinidae (16% of species each), Mormyridae (11% of species) and Alestidae (10% of species) werethe most abundant. The influence of environmental parameters such us width, dissolved oxygen, turbidity, depth, canopy closure, mixed sand-gravel and aquatic plants on the distribution of fish population has been highlighted by a redundancy analysis (RDA) coupled with Monte Carlo test 499 permutations.
The ichthyofauna of Hana basin (Taï National Park, Côte d'Ivoire) was studied during two seasons (rainy and dry seasons) at January 2012 and November 2012. The distribution of fish species was recorded at 7 stations on the Hana basin. Fourty one fish species were collected from 28 genera and 16 families: 4 marine and/or brackish water species (Pellonula leonensis, Pellonula vorax, Sarotherodon galilaeus, Sarotherodon melanotheron). As regards the families and species number, the Siluriform order was contained the most important families and species (31.25% of families and 21.95% of species). They are followed by Characiform (18.75% of families; 19.51% of species), Osteoglossiform (12.50% of families and 14.63% of species) and Cyprinodontiform (12.50% of families and 4.88% of species).The spatial distribution of fish species indicated a more diversified settlement in the main channel of Hana basin. The high value for taxonomic richness was obtained in the dry season. The diversity index varied significantly in both seasons. The quantitative analysis indicated that Schilbeidae, Alestidae and Mormyridae were the main families which dominated Hana basin. In the main channel, Spatio-Temporal Patterns of Fish Assemblages and Influential Environmental Gradients in a West African Basin (Tai National Park, Côte D'ivoire) 146 Schilbeidae was the abundant family while Alestidae and Clariidae were respectively abundant families of Moumo and Meno tributaries. The main environmental factors determining the patterns of fish distribution and assemblage structure in Hana basin were canopy closure, width, sand, depth, mud, temperature, mixed clay-mud, gravel and leaves-wood.
Abundance and fish species composition of Gerado and Dirma Rivers, South Wollo, Ethiopia
Journal of Fisheriessciences.com, 2016
Abundance and fish species composition of both Gerado and Dirma Rivers were studied in dry and wet season from February to November 2014.The objectives of the study were to assess fish species composition, relative abundance and recommend sustainable fishery management to help biodiversity conservation in aquatic ecosystem. Gillnet with mesh size of 6-10 cm were used to catch the fish species, sensitive balance was used to measure weight of the fish in gm and Ruler was used to measure total length of the fish species in cm . Shannon diversity index was used to compare species diversity in both rivers between seasons. Univarate analysis and t test were used to test species composition and abundance difference in both rivers between sites and season through application of SPSS Version 16 .In both rivers , abundance and fish species composition were more in dry season than wet season. The Shannon diversity index(H') value were 1.78 and 1.66 in dry and wet season respectively for Ge...
Pan Africa Science Journal
Despite significantly influencing fisheries characteristics of major global basins, medium-sized rivers such as Awach Kibuon remain the least studied. This study evaluated longitudinal fish species diversity, distribution, and environmental influence in Awach Kibuon River, Lake Victoria Basin, Kenya, to inform sustainable management of fisheries resources within the region. Nine sites located in different zones of the river were sampled monthly for eight months in 2019 and 2020. Fish samples were collected for 45 minutes using a backpack electrofisher on a 50-m river reach in every sampling site. Selected physico-chemical parameters (pH, total dissolved solids (TDS), dissolved oxygen (DO), temperature, conductivity, and turbidity) were measured in situ using standard methods. Longitudinal river fish diversity was assessed using species richness, Simpson's Index (D), Shannon-Weiner Index (H′), and Pielou's Evenness Index (J). A total of 983 fish specimens belonging to 21 spec...
Freshwater Fish Diversity of a Tropical Rainforest River in Southeast Nigeria
Fish samples were collected at three stations twice per month from January to December 2013 with the help of local fishers using hook and line, gill net, cast net, bagnet and local traps for ecological studies of important fish species and resource management issues of Oramiri-Ukwa River, southeast Nigeria. An estimate of 25 fish species, 15 genera, 21 families and six orders were obtained. Ecological indices indicate a polydiverse community and no single species exhibited true dominance (≥ 50%). Paired group cluster analysis establishes Tilapia zilli and Hemichromis fasciatus as the focal species and identifies the associated species combinations that characterize spatial variability and account for the biodiversity resources and structure of the artisanal fishery. Other important species include Tilapia mariae>Synodontis nigrita while Polypterus senegalus>Parachanna africana and Shilbe mystus were the least in number. Monospecific and rare fish species of ecological and conservation significance identified include Ctenopoma kingsleyae, Clarias gariepinus as well as Erpetoichthys calabaricus and Pantodon buchholzi derived from interconnections with other African rivers. This study presents lower fish diversity compared to earlier reports. This difference may be linked to increased human activities and fluctuating biotic and abiotic factors of the ecosystem, among others. 1. Introduction Ichthyodiversity refers to variety of fish species depending on the context and scale; it could refer to alleles or genotypes within piscian population, to species or life forms across aqua regimes (Burton et al., 1992). Fishes are the important elements in the economy of many nations as they have been a stable item in the diet of many people. According to Ehrlich & Willson, (1991) biodiversity is essential for stabilization of ecosystem, protection of overall environmental quality for understanding intrinsic worth of all species on the earth. Freshwater biodiversity has declined faster than either terrestrial or marine biodiversity over the past 30 years (Jenkins, 2003). Biodiversity is often ambiguously misused or overused to describe population dynamics of a location or community (Lawson & Moduke, 2010). Declining river flow rates (discharge) have been a major cause of species loss and are likely to be further reduced by warming temperatures, reduced precipitation and increased water withdrawal for agriculture and other human uses (Plafkin et al., 1989). Future declines can therefore negatively affect freshwater biodiversity. Inland waters and freshwater biodiversity constitute a valuable natural resource, in economic, cultural, aesthetic, scientific and educational terms. The streams and rivers are facing number of environmental problems throughout the world largely associated with anthropogenic activities in their catchment areas (Young et al., 2004). The adverse effects of human activities have resulted in degradation of stream and reverine ecosystem which ultimately alters the structure and function of stream biota. Their conservation and management are critical to the interests of all human, nations and governments. According to Nwafili & Tianxiang (2007), artisanal fishery continues to dominate fisheries, contributing over 85% of total fish production. The inland water and coastal seas are fully exploited and the increase in fishery production is not likely. Nigerian inland water bodies are primarily utilized for fishing by fisher folks. The greater part of inland fisheries is artisanal in nature supplying families with food and income. Artisanal fishing usually is usually not a full-time activity but rather integrated with farming and other activities. The main aim of this study is to provide multi-gear and multi-species ichthyofaunal composition and spatial distribution of the Oramiri-Ukwa River in comparison with others in order to share, update information, and provide data for future analysis. This study also seeks to identify species of ecological significance in the study area and to promote discussions for the management of the fishery to avoid risk of fish stock collapse and loss of invaluable ecosystem goods. 2. Materials and Methods The Study Area was Orammiri-Ukwa River (Fig. 1) located at Azaraegbulu, Emekuku in Owerri North Local Government Area of Imo State, southeast Nigeria at approximately latitude 5 0 30 ′ N and longitude 7 0 19 ′ E. Oramiri-Ukwa is a typical rain forest River. On both sides of the main River channel are large fringes of heavily forested swamps dominated by the raffia palm. The river flows from a highland in Okigwe and joins the Mbaa River to flow through Okahia Ezihe in Isiala Mbano Local Government Area, through Opara-nadim in Mbaise to
Journal of Applied Biosciences, 2017
Objectives: The interest of this study is double. Firstly, these results allow for the characterisation of species assemblages, to identify their spatial distribution boundaries. Secondly, these findings are relevant to define spatial or ecosystem units in order to provide background for fisheries management. Methodology and Results: Samples were collected and studied at a grid of three zones during the cruise of investigation on board the Oceanographic Vessel ITAF DEME in March 2012. Forty-seven taxa belonging to four orders (Cephalopoda, Malacostraca, Chondrichtyes and Osteichtyes) were selected for analysis. Spatial differences in fish structure were analysed through different multivariate routines from PRIMER including between-matrix analysis of similarities (ANOSIM), species contributions to similarity/dissimilarity (SIMPER), non-metric multidimensional scaling (MDS) and group average cluster analysis. Typical or abundant species from those zones included fishes from the families Sparidae, Haemulidae, Carangidae. The most abundant species were Ariomma bondi (Ariommidae), Selene dorsalis (Carangidae), Brachydeuterus auritus and Pomadasys incisus (Haemulidae), Pagellus bellottii (Sparidae). The species Sardinella maderensis, Brachydeuterus auritus, Trachurus trecae and Selene dorsalis had the highest frequencies of occurrence. Conclusion and application: The distribution of the species halieutics is not uniform along the coast of Côte d'Ivoire. This study pointed to the fish resources of Côte d'Ivoire's Exclusive Economic Zone. These results will be used by the fishermen and for the development of adequate measures to prevent the loss of aquatic biodiversity.
International Journal of Biological and Chemical Sciences, 2020
The insufficiency of information on fish assemblages has limited the ability to carry out effective conservation measures, hence failing to address economic and ecological roles of fish. Therefore, the present study aimed at characterizing the fish community in the upper part of Volta River basin and drawing up their influence on fisheries" sustainability. From 2009 to 2014, fish individuals were collected in nine sampling areas belonging to the Volta catchment, mainly in the catchment of Nakanbé and Mouhoun rivers that are the two major tributaries. More than 40,000 fish specimens were collected in over 600 mesohabitats by using several types of fishing gears (gill nets, cast nets, long lines and electric fishing gears). Altogether, 79 fish species belonging to 41 genera grouped in 19 families were identified. The most common species were Enteromius macrops (50.71%), Brycinus nurse (35.32%), Enteromius ablabes, Oreochromis niloticus (47.10%), Sarotherodon galilaeus (47.88%) and Coptodon zillii (42.23%). The fish species richness varied according to the sampling area. The main trend is that the protected area of Nazinga is the most diverse thus would be regarded as an appropriate refuge for fish species.
Journal of Fisheries Research, 2020
Information regarding fish diversity and relative abundance at mesohabitat level plays important roles in monitoring, protecting or managing fish populations and their habitats. Although the presence of different fish species has been reported in Gumara River by various studies, organized information on abundance and diversity of fish species at mesohabitat levels were not available. Such information is very important for the management of the declining fish fauna of Lake Tana. So, this study aimed at investigating the abundance and diversity of fish species at the mesohabitat level. Diversity and relative abundance of fishes have been studied in the Gumara River and its tributaries from November 2018 to April 2019. Physico-chemical parameters of water were measured using the in-situ multi-probe system. Fish sampling was conducted using a technique called point abundance sampling by electrofishing. Fish species identification was done by using reference books and specimens deposited in the laboratory at Bahir Dar fisheries and other aquatic life research center. A total of 3,880 fish specimens were collected from all sampling sites. Among the collected specimens, the most (53.14%) and least (0.26%) dominant were Enteromius humilis and Labeobarbus intermedius, respectively. Both of them are cyprinids. In addition to cyprinids, specimens from family Cichlidae (O. niloticus) and Clariidae (C. gariepinus) were examined and contributed only 0.67 and 0.34%, respectively. There was a significant variation in the abundance of species between habitats and sampling months. Shannon's index (H'=1.21) and evenness value (J'=0.53) in the Gumara River indicate moderate pollution and uniform distribution of individuals. Among the six sampling sites, the highest (H'=1.30) and lowest (H'=0.94) diversity indices were recorded at sites in the upstream near Wanzaye hot spring and below the bridge, respectively. In terms of mesohabitat, the species diversity and evenness were higher in riffle (H'=1.25, J'=0.57) than run (H'=1.15, J'=0.55) and the pool (H'=1.11, J'=0.50). The result revealed that the abundance and diversity of fish in Gumara River varied between sites and mesohabitats and this might be due to attitudinal difference, physico-chemical parameters and impact of different human activities around the river. Therefore, emphasis should be given to the factors which may lead to the collapse of the fish habitats, especially water abstraction for irrigation. Detailed studies on the diversity, abundance, reproductive biology by collecting yearround data should be done to use them as management tools.