Department Of Marine Sciences

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https://ir.unilag.edu.ng/handle/123456789/3388
From its inception in 1962, the University of Lagos has been identified as a potential centre for the development of Marine Biology and Fisheries in Nigeria. At that time, it was the only University/ Institution in Nigeria situated by the sea and it was obvious that it was most suitable for the development of such disciplines. In the absence of a Faculty of Agriculture and taking full benefit of its location by the sea, lagoon and river, the University of Lagos is one of the very rare institutions in the world suitable for the establishment of a Marine Biology and Fisheries programme.

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    Open Access
    Physico-chemical and macrobenthic faunal characteristics of Kuramo Water, Lagos, southern Nigeria
    (African Journal of Aquatic Science, 2004) Ogunwenmo, C. A.; Edokpayi, C.A.; Lawal, M.O.; Okwok, N.A.
    A five-month study in 2001 of an enclosed lagoon, Kuramo Water in southern Nigeria, exposed to urban perturbation describes its physical, chemical and macrobenthic invertebrate characteristics. Of the 16 physical and chemical conditions studied at four sites within the bank-root biotope, only BOD and TDS content were significantly different between sites. The elevated level of these perturbation indicators could be related to the raw and treated domestic sewage released directly into Kuramo Water from point and non-point sources. A total of 16 taxa and 691 macrobenthic individuals belonging to 11 families were recognised at the study sites. A naidid and a chironomid species were the most abundant, occurring in high numbers throughout. Other invertebrate groups occurred in low numbers. The diversity indices calculated supported this trend. The generally low diversity further supports the observation that Kuramo Water is a disturbed environment. The absence of molluscs in the benthic invertebrate samples of this study, compared to their dominance in earlier studies of Kuramo Water, reflects a modification in the habitat resulting from a change in the salinity from brackish to freshwater.
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    Open Access
    Biodegradable rice husks in laying bird's diet: Performance and egg quality parameters
    (Livestock Research for Rural Development, 2004) Iyayi, E.; Onilude, A.; Eniola, I.; Aderolu, A. Z.
    Rice husks were subjected to biodegradation using the fungus Trichoderma viridii, and included in traditional diets for laying hens at rates of 20, 30 and 40%; a diet with 20% undegraded rice husk was used as control. Biodegradation of rice husk led to improvements in nutritional composition (higher crude protein; less fibre) than the untreated material. However, there was no difference in feed intake or hen-housed egg production between the diets with undegraded or biodegraded rice husk at the 20% level. Increasing the level of biodegraded rice husk from 20 to 40% resulted in a linear decrease in egg production.
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    Open Access
    Nutrient digestibility and egg production of laying hens fed graded levels of biodegraded palm kernel meal
    (Ghana Journal of Agriculture Science, 2005-05-07) Aderolu, A. Z.; Iyayi, E. A.; Onilude, A. A.
    A 20-week feeding trial involving 72 Isa brown-laying birds, in a completely randomized design, evaluated the nutrient digestibility and egg production of layers fed diets containing biodegraded palm kernel meal (PKM) at dietary levels of 20 per cent undegraded and 20, 30 and 40 per cent biodegraded PKM, respectively. Biodegradation slightly improved proximate and detergent fibre components compared to the undegraded sample. Among the fibre fractions, hemicellulose was most degraded, whereas acid detergent lignin was least. Proximate component digestibility was similar among the diets except at 40 per cent levels. With the detergent fibre component, increasing the level of the biodegraded PKM caused a significant difference (P<0.05) in fibre component digestibility. Increase in the quantity of biodegraded PKM resulted in significant differences in the values determined for feed intake, hen-day production, and average egg weight; but for egg length, yolk index, egg/yolk ratio and egg shell thickness, there was no significant difference. Despite the significantly lower hen-day production of Diet 3, the feed cost per egg produced was similar to the value determined for birds on Diet 1. It could, therefore, be concluded that when prices for soybean meal and maize are high , up to 30 per cent PKM could be used in layers’ diets.
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    Open Access
    Changes in Nutritional Value of Rice Husk during Trichoderma viride Degradation
    (Bulgarian Journal of Agricultural Science, 2007) Aderolu, A. Z.; Iyayi, E. A.; Onilude, A. A.
    Possible improvement in nutritional status of rice husk using Trichoderma viride a fungus was investigated over a period of 40 days. Proximate composition was significantly (P<0.05) improved with microbial treatment except the ether extract, which fell on day 40. With the mineral content of the biodegraded samples, both the calcium and sodium contents rose, the only exception being the potassium content, which fell below that of the undegraded sample. Biodegradation also resulted in improvement in the energy content of the treated samples when compared to the untreated but no regular pattern was observed over the period studied. Significant reduction in the cell wall content of the rice husk was observed as the period of degradation increases. The least value for NDF and ADF was obtained on Day 40 while the least value for hemicelluloses was obtained by the 30th day.
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    Open Access
    The Phytoplankton Composition, Abundance and Temporal Variation of a Polluted Estuarine Creek in Lagos, Nigeria
    (2007-05-01) Onyema, I.C
    The phytoplankton composition, abundance and temporal variation of a polluted estuarine creek in Lagos was investigated for 6 months (February – July, 2003).Strong positive correlation (≥7.3) recorded between physico-chemical characteristics at two stations within the creek likely point to their control by similar factors, chiefly hydro-meteorological forcings and the creeks pollution status. A total of 48 taxa from 26 genera and 3 classes namely bacillariophyceae (37 taxa), cyanophyceae (10 taxa), and shizomycetes (1 taxon) were recorded for the study. Higher phytoplankton diversity recorded during the rains was probably due to the additional recruitment from the phytobenthic community as a result of scouring of the creek by floodwaters. The bacterium - Beggiatoa alba was the most abundant and frequent taxon particularly in the wet months and strongly indicates high levels of bio-degradable waste contamination. The physico-chemical characteristics and phytoplankton indicator species reflect a polluted and rapidly deteriorating estuarine environment.
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    Open Access
    Histopathology of Nile Tilapia (Oreochromis niloticus) Juveniles Exposed to Aqueous and Ethanolic Extracts of Ipomoea Aquatica Leaf
    (Academic Journals, 2007-12-09) Ayoola, S.O
    The effect of aqueous and ethanolic extracts of Ipomoea aquatica leaf on the histopathology of selected organs of the fresh water Oreochromis niloticus was investigated. The differential acute toxicity of aqueous and ethanolic extracts of aquatica leaf on Nile Tilapia, O. niloticus were carried out under laboratory conditions. The LC50 after 96 h of exposure for aqueous and ethanolic extracts of Ipomoea aquatica were 2.659 and 0.196 g/L, respectively. These values showed that ethanolic extract of I. aquatica was more toxic than its aqueous extract. Signs of agitated behaviours, respiratory distress and abnormal nervous behaviours including eventual deaths were observed in exposed fish. Control fish neither died nor exhibited any unusual behaviour. Histopathological changes of gill, liver and muscle were noticed when O. niloticus was exposed to aqueous extract of I. aquatica for 96 h. In the gills, filament cell showed lesion, necrosis, malignancy, cellular degeneration and inflammation. In the liver, there was vacuolation of hepatocytes, inflammation and necrosis. In the muscle there was mild lesion, necrosis, inclusion bodies, inflammation and cellular degenerations. Similar result was obtained when the tested organism (O. niloticus) was exposed to ethanolic extract of I. aquatica for the same duration and under the same laboratory conditions. But the level of tissue and organ degeneration is more severe in the case of the ethanolic extract than in aqueous extract. This investigation revealed that leaf of I. aquatica has piscicidal property and can be put into use in the control and management of fish ponds by farmers. Therefore, this plant can actually be use as a biological control in eradicating predators and unwanted organisms in the ponds by farmer instead of using agrochemicals.
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    Open Access
    The Fishery and Bionomics of the Swimming Crab Callinectes Amnicola (Deroucheburne 1883) from a Tropical Lagoon and its Adjacent Creek, South-West Nigeria
    (Academic Journals Inc., 2008) Babatunde, E.E
    The fishery and the bionomics of the swimming crab Callinectes amnicola from Lagos lagoon and its adjacent creek, south-west Nigeria was investigated from October 2003 to March 2004. The results indicate that the lift net was highly selective for the crab. The wire basket trap was more tedious to operate because of the fencing and gear fixing techniques that are needed for proper installation. The longevity of the wire trap was 3 to 3½ months. The Catch Per Unit Effort (CPUE) (number of crabs per traps) ranged between 2.5 and 15 crabs for lift nets; between 5.6 and 17 crabs for wire basket traps. C. amnicola were more abundant at depth 1.5 and 2.0 m in the lagoon. The maximum size of crab from the lagoon catch and creek was 16.6 cm with a weight of 348.5 g. The crab exhibited positive allometric growth. The condition factor was higher in males than females and increased in crab size. The fecundity ranged between 1,148 and 736,266 eggs, the average number of eggs per females was 141,290. Male: Female ratio was 1:0.39. A larger proportion of stomachs from the samples contained food (80.8%) with very few (19.2%) with empty stomach. The major food items were molluscs and crustaceans, apart from fishes and algal filaments which formed only between 0.4 and 4.0% of the food of C. amnicola from the lagoon and the creek. There was no variation in the feeding habits in relation to size.
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    Open Access
    Fish resources and Physico-chemical parameters of Lagoon waters of Ogun waterside Local Government Area, Ogun State, Nigeria.
    (Department of Agricultural Extension, University of Ibadan, 2008) Idowu, A.A; Ayoola, S. O.
    A study was conducted to determine distribution and abundance of fish over two years (dry and wet seasons) in lagoon systems of Ogun waterside Local Government Area, Ogun State, Nigeria. Fish sampling was carried out in four selected stations based on catch. Physical and chemical characteristics of the lagoon systems were also carried out. The study revealed that Bagridae represented by Chrysichthys nigrodigitatus contributed the highest number of fish in the two seasons. Fish species were evenly distributed in the wet seasons than dry seasons. Simpson index (D) computed for the 4 sites are 0.15, 0.11, 0.62 and 0.12 respectively for Makunomi, Idaleketa, Iwopin and Ebute-Ilamo in the dry season and 0.37, 0.10, 0.42 and 0.10 for wet season. There are positive correlations between fish number and some physico-chemical parameters, phosphate (r= 0.74), Nitrate (r= 0.4*). There are variations among physico-chemical parameters of water samples. Information revealed by this study will be useful in fisheries resource management for the studied locations.
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    Open Access
    Pollution status and physico-chemical parameters of soil of wetland areas in Oyo State
    (Department of Aquaculture & Fisheries Mnagement, Federal University of Agriculture, Abeokuta, Ogun State, 2008) Ayoola, S. O.
    Residues of agrochemicals used in intensive farming in wetlands of Nigeria are discharged into the aquatic environment through runoff or wind drift, which affects aquatic life. This study was conducted to establish baseline information on major agrochemicals in use for wetland farming in Oyo State and to examine and soil characteristics. Chemical analysis for pesticides were performed by reverse-phase high performance liquid chromatography (HPLC) on fish and analysis on soil was carried out using AOAC standard. The result revealed that Glyphosate and Cypermethrin were mostly used. The rate of agrochemical usage varied significantly (P <0.05) among the location examined with Ajinapa (Orire LGA) having the highest rate while Papa- Eleye (Oluyole LGA) had the lowest. Analysis of fish to detect agrochemical levels indicated that the concentration of Glyphosate and Cypermethrin recorded were below the threshold level of 2µg/kg. The soil was generally sandy loam with pH ranging from 6.07 to 7.08. The physical characteristics of the soil did not very significantly (P> 0.05) between sites and season while the chemical components varied significantly (P <0.05) with sites. Uncontrolled agrochemicals usage should be avoided by wetland farmers to reduce water pollution and loss of fish biodiversity.
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    Open Access
    Histopathological Effect of Glyphosate on Juvenile African Catfish (Clarias gariepinus).
    (International Digital Organization for Scientific Information, 2008) Ayoola, S. O.
    Most aquatic herbicides have undergone some toxicity testing for effects on non-target aquatic organisms, little of this testing has been conducted on early life stages of Clarias gariepinus. African catfish C. gariepinus were exposed to acute concentrations of glyphosate for 96hrs. The lethal concentration (LC ) 5O value of glyphosate was 0.295 mg lG1 for 96h of exposure. The mean mortality percentages were 0, 0, 43, 73, 93 and 96% in the order of concentration of 0, 19, 42, 94, 207 and 455 mg lG1, respectively. Glyphosate concentration corresponding to the 96h LC value for juvenile C. gariepinus was used to study the effects of 5O glyphosate exposures in inducing histopathological changes of gills, liver, kidney and brain. In the gills, cellular infiltrations were observed. In the liver there was fatty degeneration, severe fat vacuolation, diffuse hepatic necrosis and darkly stained specks of necrotic nuclei and infiltration of leukocytes. In kidney there was haematopoietic necrosis and severe pyknotic nuclei. The brain showed mononuclear infiltration, neuronal degeneration and spongiosis. These changes occurred predominantly in the 96h exposure. Respiratory stress, erratic swimming and death of fish were observed in exposed fish which varies with the concentration of the toxicant and its showed that mortality increased with increasing in concentration. Glyphosate is toxic to juvenile fish. C. gariepinus are more susceptible to herbicide, therefore their use on/near fish farm or in area close to aquatic environment should be discouraged.
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    Open Access
    Effects of acute and sub-lethal concentrations of phostoxin on weight changes and haematology parameters of Clarias Gariepinus
    (Journal of Environmental Extension, 2008-01) Aderolu, A. Z.; Ayoola, S. O.; Agwu, K. I.
    Fish are sensitive to a wide variety of chemicals and toxic conditions. In aquatic environment, organophosphate may cause several physiological and biochemical defects in fishes. Clarias gariepinus (mean weight 10±0.1g) was exposed to acute and sub-lethal concentrations of phostoxin to evaluate the toxicity of phostoxin organophosphate. Effect of phostoxin on haematological parameters and weight changes of juvenile Clarias gariepinus was also investigated. The concentrations used during the acute toxicity test were 1.00, 2.0, 4.00, 6.00 mg/l with a control of 0.00mg/l; while the concentrations of the toxicant used during the 28-days sublethal exposure were 0.60, 0.40, 0.20 mg/l with a control of 0.00 mg/l. The lethal concentration (LC50) value of phostoxin was 2.20mg/l for 96h of exposure. The results obtained from the sublethal exposure showed that there was a progressive decrease in weight gain of fish as the concentration of the toxicant increased. Also, haematological indices indicated that the fish became hyperglycaemic and hypoproteinaemic and the severity of this condition were directly proportional to the phostoxin concentration. C.gariepinus is susceptible to phostoxin; therefore use of phostoxin in disinfection on/near fish farm or area close to aquatic environment should be discouraged.
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    Open Access
    Effects of Acute and sub-lethal concentrations of phostoxin on weight changes and haematology parameters of Clarias gariepinus.
    (Department of Agricultural Extension and Rural Development, University of Ibadan, 2008-01) Aderolu, A.Z.; Ayoola, S. O.; Agwu, K.I
    Fish are sensitive to a wide variety of chemicals and toxic conditions. In aquatic environment, organophosphate may cause several physiological and biochemical defects in fishes. Clarias gariepinus (mean weight 10±0.1g) was exposed to acute and sub-lethal concentrations of phostoxin to evaluate the toxicity of phostoxin organophosphate. Effect of phostoxin on haematological parameters and weight changes of juvenile Clarias gariepinus was also investigated. The concentrations used during the acute toxicity test were 1.00, 2.0, 4.00, 6.00 mg/l with a control of 0.00mg/l; while the concentrations of the toxicant used during the 28-days sublethal exposure were 0.60, 0.40, 0.20 mg/l with a control of 0.00 mg/l. The lethal concentration (LC50) value of phostoxin was 2.20mg/l for 96h of exposure. The results obtained from the sublethal exposure showed that there was a progressive decrease in weight gain of fish as the concentration of the toxicant increased. Also, haematological indices indicated that the fish became hyperglycaemic and hypoproteinaemic and the severity of this condition were directly proportional to the phostoxin concentration. C.gariepinus is susceptible to phostoxin; therefore use of phostoxin in disinfection on/near fish farm or area close to aquatic environment should be discouraged.
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    Open Access
    Fish resources of Lagoon waters of Ogun waterside Local Government Area, Ogun State, Nigeria
    (Department of Forestry, University of Ibadan, 2008-08) Idowu, A.A; Jenyo-Oni, A; Ayoola, S. O.
    A study was conducted to determine distribution and abundance of fish over two years (dry and wet seasons) in lagoon systems of Ogun waterside Local Government Area, Ogun State, Nigeria. Fish sampling was carried out in four selected stations based on catch. Physical and chemical characteristics of the lagoon systems and fish distribution was also carried out. The study revealed that Bagridae represented by Chrysichthys nigrodigitatus contributed the highest number of fish in the two seasons. Fish species were evenly distributed in the wet seasons than dry seasons. Simpson index (D) computed for the 4 sites are 0.29, 0.14, 0.14 and 0.29 respectively for Ode-Omi, Awodikora, Eba and Ebute-Okun in the dry seasons and 0.09, 0.10, 0.07 and 0.09 for dry seasons. There are positive correlations between fish number and some physico-chemical parameters, phosphate (r= 0.74), Ammonia (r= 0.4*). There are variations among physico-chemical parameters of water samples. Information revealed by this study will be useful in fisheries resource management for the study locations.
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    Open Access
    Biotechnology and Species Development in Aquaculture.
    (Academic Journal, 2008-09-30) Ayoola, S. O.; Idowu, A.A
    The use of biotechnology in various aspects of human endeavour have obviously created a great impact but not without some risks. Not withstanding, there is still the need for its adoption as more of the already adopted biotechnologies are being improved upon with lesser demerits. Aquaculture is not also left out in the application of biotechnological approaches. The aquaculture industry is currently faced with solving the simultaneous problems of developing economically viable production systems, reducing the impact on the environment and improving public perception. Whereas significant progress has been made in understanding production systems, improvement in cultured stocks has not kept pace with productivity demands. This paper considered aquaculture as the only way to increase fish production and also discusses technical environmental and management considerations regarding the use of genetically modified fish organism (e.g. fish) in aquaculture. This paper discusses advantage of biotechnological research application and commercialization.
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    Open Access
    Histopathological Effect of Cypermethrin on Juvenile African Catfish (Clarias gariepinus)
    (ISPROMS, 2008-11-15) Ayoola, S. O.; Ajani, E.K
    The acute toxicity of cypermethrin an insecticide, to juvenile African catfish, C. gariepinus was investigated with emphasis on histopathological effects. Clarias gariepinus (Burchell 1822) juvenile were exposed to 0, 1.9, 4.1, 9, 21, and 45mg/l of cypermethrin. The lethal concentration (LC50) value of cypermethrin was 0.063mg/l for 96h of exposure. The mean mortality percentages were 0, 0, 70, 90, 100 and 100, in the order of concentration of 0, 1.9, 4.1, 9, 21 and 45 mg/L respectively. Cypermethin concentration corresponding to the 96h LC50 value for juvenile C. gariepinus was used to study the effects of cypermethin exposures in inducing histopathological changes of gills, liver, kidney and brain. In the gills, filament cell proliferation, cellular infiltration, haemorrhage and epithelial lifting were observed. In the liver, there was vacuolation of hepatocytes and necrosis. In kidney there was exfoliation and swollen with pyknotic nuclei. The brain showed neuronal degeneration and spongiosis. These changes occurred predominantly in the 96h exposure. Respiratory stress, erratic swimming and instant death of fish were observed in exposed fish, which varies with the concentration of the toxicant and it’s showed that mortality increased with increase in concentration. Cypermethrin is highly toxic to juvenile fish.
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    Open Access
    Toxicity of Herbicide, Glyphosate on Nile tilapia (Oreochromis niloticus) Juvenile.
    (Academic Journal, 2008-12) Ayoola, S. O.
    Fish are particularly sensitive to a wide variety of agrochemicals including glyphosate herbicide that may arise from not only deliberate discharge of these chemicals into waterways but also from approved agricultural practices. In the present study, the toxicity of glyphosate an herbicide was investigated with emphasis on histopathological effects. Nile tilapias (Oreochromis niloticus) juvenile 15 ± 1.0 g were exposed to 0, 2, 9, 30, 97, 310 mg/l of glyphosate. The lethal concentration (LC50) value of glyphosate was 1.05 mg/l for 96 h of exposure. Glyphosate concentration corresponding to the 96 h LC50 values for juvenile tilapia was used to study the effects of glyphosate exposure for 4 days in inducing histopathological changes of gills, livers, kidneys and brains. In the gills, filament cell proliferation, lamellar fusion, lamellar cell hyperplasia, and epithelial lifting were observed. In the liver, there was vacuolation of hepatocytes and necrosis. Kidney lesion consisted of hyaline droplets in the tubular epithelial cells and pkynosis. The brain lesion also consisted of generalized neuronal degeneration and spongiosis. The changes in these tissues occur predominantly in the 96 h exposure. Respiratory stress, erratic swimming and instant death of fish were observed in exposed fish, which varied with the concentration of the toxicant and this showed that mortality increased with increase in concentration. Glyphosate is highly toxic to Nile tilapias, which are more susceptible to this herbicide; therefore their use near fish farm or in area close to aquatic environment should be discouraged.
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    Open Access
    The biology of the smooth swim crab, Portunus validus (Herklots) off Lagos coast, Nigeria.
    (2009) Lawal-Are, A. O.; Bilewu, B.
    The size composition, growth pattern, food and feeding habits, fecundity and sex ratio of the smooth swim crab, Portunus validus (Herklots) off the Lagos Coast, Nigeria were investigated. The carapace length of the 618 specimens examined ranged between 4.5cm and 11.4cm (carapace width 9.2cm to 19.5cm) and weighed 82.3g to 694.0g. The crabs exhibited negative allometric growth in both sexes. There was high correlation between carapace width and body weight of the crabs with correlation coefficient (r) ranging between 0.889 and 0.911. The condition factor ranged between 3.78 and 5.46 with a mean of 4.85. The condition factor decreased with increase in crab size. The crabs fed mainly on fishes, molluscs, crustaceans, plant parts and algae. There were distinct differences in the feeding habits in relation to size. The small crabs fed mainly on shrimp appendages while larger crabs fed mostly on fishes and molluscs. The sex ratio was 1: 2.2 which was significantly different from the expected 1: 1 ratio. The fecundity ranged between 806,000 and 6,240,000. The average fecundity was 2,200,310. The egg diameter ranged from 0.28mm to 0.45mm. The mean egg diameter was 0.34mm.
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    Open Access
    Monoculture of freshwater shrimps (Macrobranchium species)
    (2009) Ayoola, S. O.; Idowu, A. A.; Lawal-Are, A. O.
    The sole reliance on wild catches of shrimps to meet the increasing demand globally can cause over fishing and destruction of shrimp fishery, pronounced by catch problem and habitat destruction. Freshwater shrimps of the genus Macrobrachium is found in West African waters and is widely distributed in Nigerian waters. These shrimps are more manageable than their marine relative where coastland culture is expensive, and there are usually many legal constraints on the use of coastland. Also construction costs are higher in saltwater and Penaeid shrimp farms sited at the coastland destroying the rich mangrove swamp ecosystem. Freshwater shrimp farms are sited inland and are not associated with the aforementioned problems. The culture of freshwater shrimps, which is well developed in Asian countries and America, is still at the infant stage in Nigeria. One of the factors limiting the development of this industry is lack of technical knowledge. The methods employed for semi intensive monoculture of freshwater shrimps. With the adoption of freshwater shrimp culture presented will make a headway and will lessen the fishing effort on the wild stock, provide employment opportunities, alleviate under nutrition and poverty, enhance rural livelihoods and contribute to foreign exchange earnings, It was recommended that more research and piloting be done on the culture of freshwater shrimps using indigenous species. The economic viability of culturing these shrimps should be investigated and research on hatchery production of their post larvae be intensified.
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    Open Access
    Effect of Malachite green Concentration on heamatological Parameters of the African catfish (Clarias gariepinus). (Bulletin of Animal Health and Production in Africa
    (African Union Inter-African Bureau for Animal Production, 2009) Ayoola, S. O.
    African cat fish (Clarias gariepinus) was exposed to 0.0, 0.10, 0.50, 1.00, 2.0, and 4.5 mg/l concentration of malachite green. The lethal concentration LC5O value of malachite green was 0.38mg/l for 96h of exposure. The effect of sub lethal concentrations of malachite green on blood composition of the Clarias gariepinus (Burchell) was also investigated under semi-static bioassays during 96h exposure. The effects of this chemical on the following fish blood parameters, mean corpuscular value (MCV), mean corpuscular heamoglobin (MCHC), packed cell volume (PCV) heamoglobin (Hb), red blood cell (RBC) and white blood cell (WBC were recorded on the sub lethal concentration of 0.19mg/L at 96h exposure. There were decreases in HB, RBC, PCV and Wbc in the fish showed at sub lethal concentration. Malachite green showed significant increase in MCV, MCH, and MCHC at 96h sub lethal exposure. The changes in heamatological examinations showed that fish treated with malachite green at sub lethal level are faced with a serious metabolic crisis and shifts to alternative methods of metabolism to overcome the toxic stress and maintain its survival in the polluted environment.
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    Open Access
    Seasonal Variation in Fish Distribution, Abundance and Physico-Chemical Parameters of Wetland Areas in Oyo State, Nigeria.
    (International Formulae Group, 2009) Ayoola, S. O.; Ajani, E.K
    A study was conducted to assess the physico-chemical characteristics and fish distribution of wetland areas of Oyo State. The results revealed incidence of pollution as a result of agricultural pollution mainly due to use of agrochemicals. The water pH, Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) were below the World Health Organization (WHO) and FEPA permissible limit in all the locations with the exception of Ajinapa where 5.0, 226.8 mg/l and 372.6 mg/l were recorded for pH, BOD and COD respectively. The level of agrochemical usage varied significantly (p < 0.05) among the locations examined with Ajinapa (Orire LGA) having the highest rate (65.0%) while papa-Eleye (Oluyole L.G.A) had the lowest (15.0%). A total of 16988 individuals, 11 fish species belonging to 7 families were found in 11 locations with Oreochromis niloticus (30.6%) and Clarias gariepinus (20.8%) dominating the catches. From the result, it is clear that high level of pollution in Ajinapa (Orire LGA) location is traceable to the use of agrochemical and therefore there is a need to take appropriate measure to preserve the aquatic life.