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Research paper thumbnail of The Ecological Balance of the Fish Community in an Aging Reservoir

Natural Resources, 2018

Reservoir fishes contribute significantly to freshwater fish resources in Nigeria. The compositio... more Reservoir fishes contribute significantly to freshwater fish resources in Nigeria. The composition, size variation and relative abundance of fishes in Opa reservoir, Southwest Nigeria, were investigated to establish the ecological balance of the various trophic groups of fishes in the reservoir. The study was carried out in view of recent reports on the decline in the quality and quantity of water in the aging reservoir. Fishes were collected from the reservoir monthly for twelve months using monofilament gill nets and wire cages. The fishes were identified to species level and the ecological balance of the fish community was calculated as a ratio of the forage to the carnivore groups by number and by weight. Data were subjected to statistical analysis using the Stata 13 software. 1915 fishes belonging to 17 species and 10 families were collected from the reservoir. The fish composition was dominated by the family cichlidae, with its 7 species accounting for 89.8% of the total catch. There were 2 species of clariidae, which made 6.2% of the total catch. The ecological balance of the fish community was 3.4 (by number) and 6.2 (by weight). The result obtained revealed that the fish community in the reservoir is ecologically balanced. Comparative analysis of the fish composition of the Opa reservoir with reports from other reservoirs in Southwest Nigeria showed that the reservoir has more fish species than most of the other reservoirs around. The study concludes that the reservoir still supports a rich, diverse and ecologically balanced fish community. It is recommended that the management of these fish resources should be key in the holistic management of the aging Opa reservoir.

Research paper thumbnail of Ecological Status of Opa Reservoir, Obafemi Awolowo University, Ile Ife, based on the Abundance and Diversity of its Planktonic Flora

Notulae Scientia Biologicae, 2018

A study investigating the spatial and temporal distribution, composition and abundance of plankto... more A study investigating the spatial and temporal distribution, composition and abundance of plankton in Opa reservoir, Obafemi Awolowo University, Ile-Ife, Southwest Nigeria, was conducted over a period of an annual cycle. The study was undertaken with a view of providing a more recent catalogue of planktonic flora and possibly an update of the reservoir’s trophic status. Quantitative net planktons were collected monthly from both the surface and bottom levels at three sampling stations established at the dam site (lacustrine), mid-lake (transition) and upper inflow (riverine) parts of the reservoir. The divisions recorded were Bacillariophyta…

Research paper thumbnail of Effect of discharges from re-channeled rivers and municipal runoff on water quality of Opa reservoir, Ile-Ife, Southwest Nigeria

African Journal of Environmental Science and Technology, 2017

Over the years, there is a direct linkage of township drains and streams to the Opa reservoir, Ob... more Over the years, there is a direct linkage of township drains and streams to the Opa reservoir, Obafemi Awolowo University, Nigeria. Hence the spatial and temporal variations of the reservoir's water quality were studied between November 2012 and October 2013 to investigate the effect of these discharges on these. Physical, chemical as well as the oxygen parameters of the water were investigated using standard techniques. The parameters determined revealed considerable temporal variations with the rainy season averaged concentration of COD, TOC, OM, TSS, TS, turbidity, apparent colour, true colour, sodium, and phosphate significantly higher (p<0.05) than those of the dry season. Spatially, DO, TSS, TS, organic matter and TOC decreased significantly (p<0.05) from riverine to the lacustrine (dam site). However, calcium, sulphate, and electrical conductivity showed significant increases (p<0.05) from the riverine zone section towards the dam site. Vertically, sulphate, bicarbonate, COD, TOC, chloride, TSS, TS, turbidity, apparent colour, true colour and sodium ion values increased significantly (p<0.05) from the surface down to the bottom. Conversely, magnesium, total hardness, nitrate, BOD, DO, electrical conductivity, acidity, carbonate, alkalinity, TDS and pH values decreased (p<0.05) from water surface to the bottom of the reservoir. Therefore, the discharges from the catchment area of Opa reservoir could pose a level of risk to the aquatic ecosystem as well as the community if not well treated before being supplied.

Research paper thumbnail of An Inventory of the Geological, Biological and Cultural Resources on Ufe-Oke Hill, Idanre, Southwestern Nigeria

Natural Resources, 2011

Idanre, which represents a unique topographical landscape within southwestern Nigeria, is being p... more Idanre, which represents a unique topographical landscape within southwestern Nigeria, is being proposed to the United Nations Educational Scientific and Cultural Organization (UNESCO) for designation as a world heritage site. In line with this, we conducted a survey to document the rich geological, biological and cultural resources contained within the Ufe-Oke section of Idanre Hills. Our geological inventory revealed two major rock types, older porphyritic granite and fine grained granite, in addition to other minerals. We identified insects belonging to 174 species while fishes from 4 species were collected. Mammals belonging to 13 species were identified through trapping, sightings and signs, although an even greater variety was inferred from interviews with hunters and visits to local fetish markets. Patterns concerning how these biological taxa are distributed altitudinally along Ufe-Oke Hill are discussed. In addition, in the quarters within Ufe-Oke representing the ancient city of Idanre, we characterized about 200 pieces of anthropological material, which included pottery shards, beads, chinaware, brass bangles and ancient metal coins. We also identified various other major features of archeological interest. Finally we offer recommendations, in the light of our findings, concerning how the variety of resources catalogued in this study can be effectively harnessed while sustaining at the same time the environmental integrity of this site, which offers the greatest opportunities and potential for tourism.

Research paper thumbnail of The Ecological Balance of the Fish Community in an Aging Reservoir

Natural Resources, 2018

Reservoir fishes contribute significantly to freshwater fish resources in Nigeria. The compositio... more Reservoir fishes contribute significantly to freshwater fish resources in Nigeria. The composition, size variation and relative abundance of fishes in Opa reservoir, Southwest Nigeria, were investigated to establish the ecological balance of the various trophic groups of fishes in the reservoir. The study was carried out in view of recent reports on the decline in the quality and quantity of water in the aging reservoir. Fishes were collected from the reservoir monthly for twelve months using monofilament gill nets and wire cages. The fishes were identified to species level and the ecological balance of the fish community was calculated as a ratio of the forage to the carnivore groups by number and by weight. Data were subjected to statistical analysis using the Stata 13 software. 1915 fishes belonging to 17 species and 10 families were collected from the reservoir. The fish composition was dominated by the family cichlidae, with its 7 species accounting for 89.8% of the total catch. There were 2 species of clariidae, which made 6.2% of the total catch. The ecological balance of the fish community was 3.4 (by number) and 6.2 (by weight). The result obtained revealed that the fish community in the reservoir is ecologically balanced. Comparative analysis of the fish composition of the Opa reservoir with reports from other reservoirs in Southwest Nigeria showed that the reservoir has more fish species than most of the other reservoirs around. The study concludes that the reservoir still supports a rich, diverse and ecologically balanced fish community. It is recommended that the management of these fish resources should be key in the holistic management of the aging Opa reservoir.

Research paper thumbnail of Ecological Status of Opa Reservoir, Obafemi Awolowo University, Ile Ife, based on the Abundance and Diversity of its Planktonic Flora

Notulae Scientia Biologicae, 2018

A study investigating the spatial and temporal distribution, composition and abundance of plankto... more A study investigating the spatial and temporal distribution, composition and abundance of plankton in Opa reservoir, Obafemi Awolowo University, Ile-Ife, Southwest Nigeria, was conducted over a period of an annual cycle. The study was undertaken with a view of providing a more recent catalogue of planktonic flora and possibly an update of the reservoir’s trophic status. Quantitative net planktons were collected monthly from both the surface and bottom levels at three sampling stations established at the dam site (lacustrine), mid-lake (transition) and upper inflow (riverine) parts of the reservoir. The divisions recorded were Bacillariophyta…

Research paper thumbnail of Effect of discharges from re-channeled rivers and municipal runoff on water quality of Opa reservoir, Ile-Ife, Southwest Nigeria

African Journal of Environmental Science and Technology, 2017

Over the years, there is a direct linkage of township drains and streams to the Opa reservoir, Ob... more Over the years, there is a direct linkage of township drains and streams to the Opa reservoir, Obafemi Awolowo University, Nigeria. Hence the spatial and temporal variations of the reservoir's water quality were studied between November 2012 and October 2013 to investigate the effect of these discharges on these. Physical, chemical as well as the oxygen parameters of the water were investigated using standard techniques. The parameters determined revealed considerable temporal variations with the rainy season averaged concentration of COD, TOC, OM, TSS, TS, turbidity, apparent colour, true colour, sodium, and phosphate significantly higher (p<0.05) than those of the dry season. Spatially, DO, TSS, TS, organic matter and TOC decreased significantly (p<0.05) from riverine to the lacustrine (dam site). However, calcium, sulphate, and electrical conductivity showed significant increases (p<0.05) from the riverine zone section towards the dam site. Vertically, sulphate, bicarbonate, COD, TOC, chloride, TSS, TS, turbidity, apparent colour, true colour and sodium ion values increased significantly (p<0.05) from the surface down to the bottom. Conversely, magnesium, total hardness, nitrate, BOD, DO, electrical conductivity, acidity, carbonate, alkalinity, TDS and pH values decreased (p<0.05) from water surface to the bottom of the reservoir. Therefore, the discharges from the catchment area of Opa reservoir could pose a level of risk to the aquatic ecosystem as well as the community if not well treated before being supplied.

Research paper thumbnail of An Inventory of the Geological, Biological and Cultural Resources on Ufe-Oke Hill, Idanre, Southwestern Nigeria

Natural Resources, 2011

Idanre, which represents a unique topographical landscape within southwestern Nigeria, is being p... more Idanre, which represents a unique topographical landscape within southwestern Nigeria, is being proposed to the United Nations Educational Scientific and Cultural Organization (UNESCO) for designation as a world heritage site. In line with this, we conducted a survey to document the rich geological, biological and cultural resources contained within the Ufe-Oke section of Idanre Hills. Our geological inventory revealed two major rock types, older porphyritic granite and fine grained granite, in addition to other minerals. We identified insects belonging to 174 species while fishes from 4 species were collected. Mammals belonging to 13 species were identified through trapping, sightings and signs, although an even greater variety was inferred from interviews with hunters and visits to local fetish markets. Patterns concerning how these biological taxa are distributed altitudinally along Ufe-Oke Hill are discussed. In addition, in the quarters within Ufe-Oke representing the ancient city of Idanre, we characterized about 200 pieces of anthropological material, which included pottery shards, beads, chinaware, brass bangles and ancient metal coins. We also identified various other major features of archeological interest. Finally we offer recommendations, in the light of our findings, concerning how the variety of resources catalogued in this study can be effectively harnessed while sustaining at the same time the environmental integrity of this site, which offers the greatest opportunities and potential for tourism.