Marine Sciences-Scholarly Publications

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    Open Access
    Accumulation of Heavy Metals in Water, Sediment and Fish Species in Ologe, Lagoon
    (Faculty of Agriculture, Nasarawa State University, Keffi, Lafia Campus, 2016) Ayoola, S. O.; Agoro, T. O
    Fish inhabiting a polluted aquatic ecosystem tend to accumulate heavy metals in their tissues. Generally, accumulation depends on metal concentration, time of exposure, way of metal uptake, environmental conditions and intrinsic factors. This study was to investigate the metal accumulation in Sarotherodon melanotheron and Chrysichthys nigrodigitatus from the water and sediments at Ologe Lagoon for period of six months (April – September, 2014). The physicochemical parameters were determined according to AOAC and heavy metals such as zinc (Zn), copper (Cu), lead (Pb), Nickel (Ni) and chromium (Cr) were determined using Atomic Absorption Spectrometry. The sequence of Bioaccumulation factor (BAF) for Sarotherodon melanotheron: Cr > Zn > Cd > Pb > Cu; while for Chrysichthys nigrodigitatus: Cu > Cr > Pb > Cd > Zn. The study showed that generally the metal concentration in the water and sediments bio accumulated in Chrysichthys nigrodigitatus and Sarotherodon melanotheron are higher in Cr, Cu, Zn, and Cd. While the Ni and Pb are less in the tissues and are regarded to be safe by WHO and FEPA. Fish at the Ologe Lagoon are still consumable though partially contaminated with slight increase in heavy metals influenced by anthropogenic activities. However, it is quite evident that there was bioaccumulation of heavy metals in fish tissues and condition may get worse. Therefore, a regular monitoring of heavy metal levels in fishes is necessary.
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    Open Access
    Acute Toxicity and Histopathological Effects of Engine Oil on Sarotherodon melanotheron.
    (International Digital Organization for Scientific Information, 2012) Ayoola, S. O.; Alajabo, O.T
    The lethal effects of engine oil effluent on Sarotherodon melanotheron was investigated using pathologic lesions in the gill, kidney and muscle. Five concentrations of 0.035, 0.07, 0.14, 0.21 and0.28 ml/l for 96hrs were used for the experiment. The randomized ANOVA for toxicity of the extract against S. melanotheron showed that there were significant differences in the test. The lethal concentration LC that caused 50% 50 mortality was approximately 1.12mg/l of the engine oil. Lesion observed in the gill epithelium exposed to at the different concentrations of the engine oil were dose dependent with the highest effluent concentration inducing the highest damages which include mild congestion, severe congestion and calcification of the gill. The Kidney tissues of S. melanotheron exposed to the engine oil effluents showed severe congestion, inflammation, cytoplasmic vacuolations which may have been due to glycolysis leading to microsomal and mitochondrial dysfunction. While the muscle tissues were normal even after the exposure. The entire test organism in the control showed inappreciable or no histologic degradation while their staining patterns and cellular arrangement remain unaffected. The result obtained showed that engine oil effluents pose a serious damage to S. melanotheron and was observed that acute concentration of engine oil effluents have histopathological effects on aquatic organisms. It can be deduced that indiscriminate discharge of industrial effluents into water bodies can induce damage to the tissue and organ, which might make the fish vulnerable to diseases and eventually lead to death of prominent edible species of the aquatic environment, Therefore there is need for the adoption of proper effluent treatment technology which would ensure proper treatment of industrial effluent and check the recurrence of oil spillage. Indiscriminate exposure of aquatic organisms to engine oil effluent should be discouraged.
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    Open Access
    Acute toxicity and histopathology of Nile tilapia (Oreochromis niloticus) fingerlings exposed to aqueous and ethanolic extracts of Euphorbia poissonii leaves
    (New Clues in Science, 2011) Ayoola, S. O.
    The lethal effect of aqueous and ethanolic leaf extracts of Euphorbia poissonii on Nile Tilapia, Oreochromis niloticus were investigated. Five concentrations of each extract were tested. The concentrations for aqueous were; 20g/L, 40g/ L, 80g/L, 160g/L and 320g/L. The concentration for the ethanolic were; 0.01g/L,0.1g/L,1.0g/L,10.0g/L and 100g/L. The randomized ANOVA for toxicity of the extracts against Oreochromis niloticus showed that there were significant differences between all treatments (P< 0.05). The 96hours LC50 values of the aqueous and ethanolic leave extracts were 7.13g/L and 0.031g/L respectively. These results showed that the ethanolic extracts were more toxic than the aqueous extracts of Euphorbia poissonii. Histopathological effects were observed in the gill and muscle of Oreochromis niloticus in all concentrations of the aqueous and ethanolic extracts. Effects in the ethanolic extracts include generalized sub mucosal congestion and severe stunting of the secondary lamella in the gills and lesions on the muscles. The effect in the aqueous extracts includes degeneration of gills and necrosis on the muscle. It is also seen that aqueous and ethanolic extracts of Euphorbia poissonii have varying histopathological effects on Oreochromis niloticus fingerlings with increasing effects in higher concentration. The direct use of Euphorbia poissonii should be discouraged in a pond system except as a biological control to disinfect the pond from predators and it is to be used in low concentrations.
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    Open Access
    Acute Toxicity of Green Liquid Detergent to the Guppy (Poecilia reticulata) and Nile Tilapia Fingerlings (Oreochromis niloticus)
    (Journal of Scientific Research and Development, 2015) Lawal, M. O.; Nwaokoro, R. C.; Ohadike, K. P.
    The acute toxicity of green liquid detergent was investigated using Poecilia reticulata and Oreochromis niloticus fingerlings in a 96 h static renewal laboratory bioassay. The 96hLC50 values were 0.06 mL/L against guppy and 0.09 mL/L against tilapia respectively. On the basis of 96hLC50 liquid detergent was 1.5 times more toxic to P. reticulata than to O. niloticus fingerlings. Symptoms of toxicosis observed in fish after their exposure include lack of balance, difficulty in breathing, erratic swimming, restlessness, skin discolouration and bleeding through gills. Results are discussed on the basis of data available on the damage caused by the exposure of teleosts to green liquid detergent. Hence, the concept of safe disposal of wastewaters into the aquatic environment should be encouraged.
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    Open Access
    Acute Toxicity Of Nile Tilapia (Oreochromis niloticus) Juveniles Exposed To Aqueous And Ethanolic Extracts Of Ipomoea aquatica Leaf
    (Nature and Science, 2011) Ayoola, S. O.; Kuton, M.P; Idowu, A.A; Adelekun, A.B
    The differential acute toxicity of aqueous and ethanolic extracts of Ipomoea aquatica leaf on Nile Tilapia, Oreochromis niloticus were carried out under laboratory conditions. The LC50 after 96hr of exposure for aqueous and ethanolic extracts of Ipomoea aquatica were 2.659g/L and 0.196g/L respectively. These values showed that ethanolic extract of Ipomoea aquatica was more toxic than its aqueous extract. Signs of agitated behaviours, respiratory distress and abnormal nervous behaviors including eventual deaths were observed in exposed fish. Control fish neither died nor exhibited any unusual behaviour. The randomized analysis of variance (ANOVA) showed that there were significant differences (P<0.05) in the quantal response (mortality) of O. niloticus to aqueous and ethanolic extracts of I. aquatica at 24hrs, 48hrs, 72hrs and 96hrs of exposure period. It was investigated that leaf of Ipomoea aquatica has piscicidal property and can be put into use in the control and management of fish ponds to eradicate predators by farmers.
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    Open Access
    Acute Toxicity of Piscicidal Plant Extracts (Adenia cissampeloides) on Tilapia (Sarotherodon galilaeus) Juveniles
    (Babol Noshirvani University of Technology, 2010) Ajani, E.K; Ayoola, S. O.
    Full texts attached
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    Open Access
    Acute toxicity of some nigerian crude oils on black jaw tilapia (Sarotherodon melanotheron) Juveniles
    (Fisheries Society of Nigeria, 2018) Omogoriola, H.O; Ayoola, S. O.
    Oil industry activities are sources of major contamination problems in Niger Delta. Pollutants from these activities have significant deleterious effects on aquatic organisms. The study investigated the LC50 values obtained from acute toxicity tests on Sarotherodon melanotheron using Oil- in-Water Dispersion (OWD) of the three selected Nigerian crude oils –Ebok, Meji and Erha. The acute toxicity concentrations of 0, 2, 4, 6 and 8ml/L, 0, 10, 15, 20, and 25ml/L and 0, 25, 37.5, 50 and 62.5ml/L were used to determine the 96h Lethal Concentration (LC50) of Ebok (heavy), Meji (light) and Erha (medium) crude oils respectively. The analysis of variance (ANOVA) showed that there were significant differences (p<0.05) in the quantal response of S. melanotheron to different concentrations of three crude oils at different hours of exposure. These results showed that 96LC50 values for OWD-Ebok, OWD-Meji and OWD-Erha crude oils on S. melanotheron were 0.56ml/L, 6.78ml/L and 24.82ml/L respectively. Based on the acute toxicity tests, Ebok with lower API (>22.30C) gravity was more toxic than other crudes on S. melanotheron. All crude oils were toxic to the fish; their discharge into the water bodies during crudes exploration and exploitation should be discouraged for a safety environment.
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    Open Access
    Acute Toxicity of Water Accommodated Fractions (WAFs) of three Nigerian Crude Oils to Clarias gariepinus (Burchell, 1822)
    (Department of Aquaculture and Fisheries Management, University of Ibadan, 2017) Omogoriola, H.O; Ayoola, S. O.
    Oil industry activities such as exploration, transportation, storage, use and disposal, as well as oil spills are sources of major contamination problems in Niger Delta, which have significant deleterious effects on aquatic organisms. The objective of this study was to report LC values 50 obtained from acute toxicity tests on the African Catfish, C. gariepinus exposed to Water Accommodated Fraction (WAF) –heavy (Ebok), light (Meji) and medium (Erha) crude oils. Acute toxicity concentrations of 0%, 2%, 4%, 6% and 8%, 0%, 15%, 20%, 25% and 30% and c 0%, 40%, 60%, 80% and 100% were used to determine the 96h Lethal Concentration (LC ) of 50 heavy, light and medium crude oils respectively. The analysis of variance (ANOVA) showed that there was a significant (p<0.05) difference in the quantal response of C. gariepinus to different concentrations of the various crude oil types at 24, 48, 72 and 96 hours exposure. These results showed that 96LC values for heavy, light and medium crude oils on C. 50 gariepinus were 0.028 mg TPH/l, 0.177 mg TPH/l and 0.742 mg TPH/l respectively. The 96LC of WAF showed that the heavy crude oil was six times more toxic than light and twenty 50 six times more toxic than medium and on toxicity categorization, the heavy, light and medium crude oils were very highly toxic, highly toxic and highly toxic on C. gariepinus. Based on the acute toxicity tests, heavy with lower API (<22.30C) gravity was more toxic than other crude oils on C. gariepinus. All crude oils are toxic to aquatic organisms especially the fish; their discharge into the water bodies during crude oil exploration, transportation, storage and even sabotage should be discouraged to protect the environment.
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    Open Access
    Antimicrobial and antioxidant properties of African medicinal plants
    (Journal of Coastal Life Medicine, 2017) Bello, M. D.; Aderolu, A.Z.; Lawal, M.O.; Soyinka, O.O.; Adeleke, T.A.
    Objective: To study antioxidant and antimicrobial properties of Terminalia catappa, Psidium guajava, Alstonia boonei, Morinda lucida (M. lucida) and Spondias mombin leave extracts using ethanol, petroleum-ether and aqueous media. Methods: The free radical 2, 2-diphenyl-1-picrylhydroazyl was used to measure scavenging activities of extracts, while phenolic and flavonoid content were estimated by spectrophotometry. Antibacterial screening of extracts was done by determining zone of inhibition using disc diffusion method. Plant extracts were tested against five strains of Gram-positive and Gram-negative bacteria. After sterilization, the discs were loaded with concentrations of broad spectrum ciprofloxacin, and prepared extract solutions of different concentrations were refrigerated for 24 h. Determination of minimum inhibitory concentration of extracts in the screening assay was according to micro-broth dilution, while determination of minimum bactericidal concentration was carried out by agar diffusion. Results: The highest radical scavenging effect was found in petroleum ether extracts of all the plants with M. lucida and Psidium guajava having the highest and lowest values respectively. Aqueous solvent recorded highest phenolic content in all extracts with the exception of M. lucida. Flavonoid content was extracted better from Alstonia boonei and M. lucida with ethanol, while aqueous solvent extracted more from the other plants. With exception of extracts from petroleum ether, all others exhibited varying levels of antibacterial activities against E. coli, Pseudomonas aeruginosa, Salmonella typhi, Vibrio cholera and Staphylococcus aureus. Conclusions: This study proved that all crude extracts showed strong antioxidant and antimicrobial potentials, which qualified them as nutraceuticals in fish feed production.
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    Open Access
    ANTIOXIDANT AND ANTIMICROBIAL ACTIVITIES OF SOME NIGERIAN GREEN LEAFY VEGETABLES
    (Ethiopian Journal of Environmental Studies & Management, 2018) Edada, U. P. ;; Lawal, M. O. ;; Aderolu, A. Z.
    This study evaluated the antioxidant and antimicrobial properties of Piper guineense, Ocimum gratissimum, Murraya koenigii and Gongronema latifolium leave extracts using ethanol, petroleum-ether and aqueous media. The scavenging activities of the extracts was measured with free radical 2, 2-diphenyl-1-picrylhydrazyl, flavonoid and phenolic contents were assessed by spectrophotometry while, gas chromatographic flame ionization detector was used for phytochemical screening of the extracts. The micro-broth dilution and agar diffusion methods were used to assess Minimum inhibitory and bactericidal concentrations of the extracts respectively. The different leaves extracts differed significantly (P<0.05) at 25, 50, 75 and 100µg/ml of radical scavenging activities, with the lowest and highest values recorded at 25 and 100µg/ml respectively. The aqueous extract of G. latifolium had the highest value (67.60 ± 0.12mg GAE/100g DW) while, petroleum ether extract of P. guineense had the lowest value (30.65 ± 0.06mg GAE/100g DW) of total phenolic content. The highest and lowest flavonoid contents were found in petroleum ether extract of P. guineense (80.75 ± 0.37mg Rutin/g DW) and in aqueous extract of M. koenigii (36.27 ± 0.62mg Rutin/g DW). Phytochemicals screening indicated that the extracts were rich in steroids, terpenoids, tannins, saponins, phlobatannins, cardiac glycosides and alkaloids. The petroleum ether, ethanol and aqueous extracts were active against the growth of S. epidermidis, P. aeruginosa, K. pneumonia, E. coli, S. aureus, and S. typhimurium. This study proved that all crude extracts showed robust antioxidant and antimicrobial potentials which, could be harnessed for both their health and nutritional benefits in fisheries.
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    Open Access
    Aspects of the Biology and Culture Trials of Cichlids from Lagos Lagoon
    (Faculty of Science, University of Lagos, 2013) Soyinka, O. O; Ayoola, S. O.; Onyema, I. C.
    The occurrence, length-frequency distribution, length-weight relationship and condition factors of 449 specimens of cichlids, Sarotherodon melanotheron, Tilapia zilli, Tilapia guineensis and Hemichromis fasciatus from Lagos Lagoon were investigated from September 2009 - February 2010. The relative abundance of the species collected from the lagoon was: S. melanotheron (45.43%), T. zilli (26.73%), T. guineensis (26.06%) and H. fasciatus (1.78%). All the cichlids were found throughout the sampling period except H. fasciatus which was collected only in February. The standard length of S. melanotheron ranged from 8.0 – 14.5cm (weight: 22.00 – 90.00g), T. zilli (SL: 8.0 – 14.5cm; weight: 32.80 – 108.00g), T. guineensis (SL: 9.0 – 17.0cm; weight: 42.00 – 85.00g) and H. fasciatus (SL: 11.0 – 14.0cm; weight: 65.00 – 84.00g). The frequency polygon reflected one age group in S. melanotheron, one age group in T. zilli, three age groups in T. guineensis and two age groups in H. fasciatus. The cichlid species exhibited negative allometric growth with regression coefficient (b) values between 0.729 – 2.0918. The K-value for S. melanotheron was 4.65 (mean, 2.07 ± 0.33); T. zilli, 3.93 (mean, 1.77 ± 0.54; T. guineensis, 3.64 (mean, 1.74 ± 0.66, and H. fasciatus, 3.63 (mean, 1.94 ± 0.28). Culture potential of S. melanotheron (53 males and 47 females) in freshwater concrete pond was also examined from August 2010 – February 2011. Average fecundity per adult female ranged between 21 and 128eggs for fish with weight ranging from 30.00g to 78.00g. The culture trial of S. melanotheron revealed its ability to tolerate and thrive in both brackish and freshwater conditions and this makes it an excellent candidate for aquaculture purposes. Proper management strategies needed to be employed in commercial production and the conservation of this rich resource in the wild.
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    Open Access
    Assessment of Aqua-Tourism Potentials in Some Fishing Sites in Bitumen Bearing Wetlands of Ondo State, Nigeria
    (International Digital Organization for Scientific Information, 2010) Akeredolu, O.E; Ayoola, S. O.
    A 24-month survey was conducted during the wet (May- August) and Dry (October ?April) season of 2004 and 2006 along eight economic fishing sites in Ondo State bearing Wetland, with the aim of determining the abundance, species diversity of some ornamental species thus promoting ecotourism potential and preventing the loss of these species in the area during and after exploitation. The study was carried out in 4 study zones namely Odigbo (S1), Ode-Aye (S2), Okitipupa (S3), and Ilaje ese-odo (S4) noted for active bitumen seepage. Fishing potential of the area was assessed using catch per unit effort method as well as physico chemical analysis of water samples obtained from designated sites in the area in accordance with AOAC methodology. Fish compositions were assessed using multifilament gillnet, of different sizes hanging from 38 mm to 178 mm. The results revealed that the area is blessed with 24 economic species of fishes belonging to 13 families which could boost the tourist potential of Ondo State. The percentage composition of families identified varies as follows: Ariidae (2.04%), Anabantidae (3.27%), Bagridae (6.36%), Channidae (4.32%), Characidae (10.62%) Cichlidae (45.65%) Clupeidae (3.94%), Clariidae (11.78%), Hepsetidae (0.95%), Mormyridae (7.42 %), Malapteruridae (1.13%), Schilbiidae (1.76%), Polypteridae (0.76%). The family Cichlidae was the most abundant in the area during the study period. The diversity of fish during the study varied with locations and season .The study showed higher fish population during the dry season than raining season and lower population in study zones highly polluted by bitumen seepages. The study emphasizes the need for sustainable resource management during bitumen exploitation.
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    Open Access
    Assessment of Fishing Practices in a Tropical Low Brackish Lagoon Ecosystem in Southwestern Nigeria
    (2010) Emmanuel, B.E
    This paper present an assessment of fishing practices in Lekki lagoon between March, 2006 and February, 2008. Lagoon fishery plays an important role in the economy of the country and the livelihoods of the people living around the lagoons. Eight different types of fishing gears were identified. Gillnets were the most operated gears in the lagoon followed by long lines. The least operated were the boat seines. Higher number of gears (N=1027) was operated in 2006/2007 than (N=995) operated in 2007/2008. The catch per unit effort (CPUE) ranged between 3.2kg/ha/day with basket and bamboo traps to 47.1kg/ha/day with boat seine net. Total fish production in Lekki Lagoon by small scale capture fisheries in 2007 was estimated at 1041.01 metric tons or 4.21 metric tonnes per square kilometer per year or 42.1 kg per hectare per year. A total of 16,960 specimens made up of juveniles and adults caught with different fishing gears types in the Lekki lagoon, were identified and classified. They comprised of eighty - one species belonging to 14 orders, 40 families and 56 genera. Community based resource management and enhancement techniques are recommended in order to improve and protract the small scale fisheries in the lagoon.
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    Open Access
    Assessment of Heavy Metal Content in Imported and Local Fish and Crustacean Species obtained within Lagos Metropolis.
    (Department of Zoology and Environmental Biology, 2018) Lawal-Are, A. O.; Adekugbe, A. L.; Odusoga, A. W.
    Fishes are known for their abilities to concentrate heavy metals in their muscles and since they play important role in human nutrition, they need to be carefully screened to ensure that unnecessary high level of some toxic trace metals are not being transfer to man through their consumption. The study was to evaluate heavy metals (chromium, lead, iron and cadmium) in imported and local species of shrimps, crabs and fish using Atomic Absorption Spectroscopy. The selected imported species were horse mackerelkote fish (Trachurus trachurus), mackerel-titus (Scomber scrombus), croaker (Pseudotolithus typus), smooth swim crab (Portunus validus) and pink shrimp (Farfantepenaeus notialis) while the local species used were; Sole fish (Cynoglossus senegalensis), Tilapia (Oreochromis niloticus), brackish water catfish (Chrysichthys nigrodigitatus), freshwater catfish (Clarias gariepinus), lagoon crab (Callinectes amnicola) and freshwater prawn (Macrobrachium macrobrachion). It was observed that there was no significant difference in the metals (Cd, Pb and Cr) between the imported and local fish species and between imported and local crustacean species. However, these metals concentrated more in the local fish species, O. niloticus (1.846±1.00 mg/100g). The mean heavy metals concentration occurred in the following decreasing order: Fe> Cd> Pb> Cr for all the samples. The mean concentrations of the analyzed heavy metals in the samples were below the maximum permissible limits as recommended by the International Atomic Energy Agency (IAEA), United Nations Environment Program (UNEP) and Federal Environmental Protection
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    Open Access
    Biochemical and Haematological Response of Clarias Gariepinus (Burchell, 1822) Juveniles Fed with diet Containing Mytilus Edulis Shell at Varying Level
    (Science alert, 2012) Ayoola, S. O.; Maduekwe, I.A
    A twelve week feeding trial was carried out to assess the effect of Mytilus edulis shell on the biochemical and haematology parameters of Clarias gariepinus juveniles, in an attempt to substitute Dicalcium Phosphate (DCP) in the preparation of fish diets. Ten fish were randomly distributed in a plastic (High density polyethylene) tank in triplicates and fed 40% crude protein commercial feed. The test fish were fed with feed containing DCP replaced with M. edulis shell at different percentage 0, 25, 50, 75 and 100%. The fish fed with diet 5 which contain 100% Mytilus edulis shell had lower Feed Conversion Ratio (FCR) when compared to the fish fed with the control diet which indicate that C. gariepinus was able to effectively utilize the M. edulis shell in the production of fish flesh. Fish fed with feed containing 100% M. edulis showed a slight decrease in haematological values of Parked Cell Volume (PCV 0.19±0.11), Haemoglobin (Hb 83.36±0.47), White Blood Cell (WBC 8.64±0.55), Mean Corpuscular Volume (MCV 89.90±0.26), Mean Corpuscular Haemoglobin (MCH 39.23±1.96) and are slightly higher in the Red blood cell (RBC 2.13±0.11), Mean Corpuscular Haemoglobin Concentration (MCHC 0.44±0.23), compared to the values of fish fed the control diet, PCV(0.37±0.01), HB (85.76±5.0.12), WBC (9.3±0.02), MCV (128.3±1.7), MCH (52.96±3.5), RBC (1.4±0.10), MCHC (0.41±0.02). It is concluded that using Mytilus edulis shell as a premix in the diet of C. gariepinus showed a slight decrease in the haematological parameters but there was no significant changes (p>0.05) thereby having no negative impact on the health status of the specie. Therefore, direct use of M. edulis shell as a premix to fish feed should be encouraged.
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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
    Biofouling of the barnacle, Chelonibita patula (Ranzani) on two portunid crabs, Callinectes amnicola (De Rocheburne) and Portunus validus (Herklots) off Lagos Coast, Nigeria.
    (2010) Lawal-Are, A. O.; Daramola, T. O.
    The frequency and distribution of barnacle (Chelonibia patula) on two economically important crabs Callinectes amnicola and Portunus validus off Lagos Coast were studied. A total of 200 crabs were examined and were of the same size range. The carapace width of C. amnicola ranged from 10.4cm to 13.4cm (carapace length 6.2 - 8.6cm) and weighed 98.0g to 168.5g. P. validus had carapace width of 10.4cm to 13.2cm (carapace length 6.2 - 8.5cm) and weighed 102.0g to 153.0g. C. patula was the only ectosymbiont on the crabs examined. The barnacles were attached to the carapace, abdomen and walking legs. The distribution, size and abundance of barnacles on the crabs were independent of the size of the crabs and were similar in both crab species. The number of barnacles on each crab varied from one to thirty-one. There was no significant difference (p<0.05) in the occurrence of barnacles on C. amnicola and P. validus. The condition factor was similar but quite low in both crab species with range of 2.59 to 4.76 (mean 3.49) in C. amnicola and 2.44 to 4.82 (mean 3.38) in P. validus.
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    Open Access
    Biology of the Hairy Mangrove Crab, Sersema huzardii (Decapoda: Graspidae) from a Tropical Estuarine Lagoon
    (2011) Lawal-Are, A. O.; Nwankwo, H.
    The size composition, growth pattern, food habits, reproductive biology and feedstuff preferences of the mangrove crab, Sesarma huzardii in a tropical estuarine lagoon were investigated. The carapace length ranged from 1.5cm to 4.7cm and weight from 4.5g to 27.8g. The crab exhibited negative allometric growth. The condition factor ranged between 3.6 and 13.5 and decreased with size. The crabs fed mainly on diatoms, algae, higher plants and insect parts. The sex ratio was 1: 0.6 (male/female) which was significantly different from the expected 1:1 ratio. The fecundity ranged between 1.2 and 3.5 million eggs. The average fecundity was 2.5million eggs. Egg diameter ranged from 0.21 to 0.33mm with a mean diameter of 0.24mm. The crab had the highest gain in weight when fed with white mangrove leaves and least with animal food.
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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
    Biomarker Responses to Environmental Stressors in the Hairy Mangrove Crab, Sesarma huzardii (Graspidae) from a Tropical Lagoon Mudflat in Nigeria.
    (2018) Usese, A. I.; Lawal-Are, A. O.; Moruf, R. O.; Chukwu, L. O.
    The study evaluated antioxidant and oxidative stress responses in the Hairy Mangrove Crab Sesarma huzadii inhabiting contaminated nearshore locations in Lagos lagoon mudflats through the catalase enzyme activity (CAT), superoxide dismutase (SOD), reduced glutathione (GSH) and Thiobarbituric Acid Reactive Substances (MDA/TBARS). The results indicates that obtained metal levels differed significantly (P < 0.05) across stations, with relatively higher mean values recorded at locations closest to domestic and solid waste dumps. Estimated Biosediment accumulation factor was highest for Copper in the tissues of S. huzadii. Relatively low levels of SOD activities were recorded in crabs from Abule-Agege and Okobaba suggests potential stress from the locations. Significant differences were also observed in anti-oxidative stress enzyme activities and lipid peroxidation levels in tissues of S. huzadii across sites. Obtained levels of antioxidant enzymes and MDA in S. huzadii further indicates increasing level of environmental stressors in the area. However, the biochemical responses of biota to the interactions between season, contaminant level, multiple stressors or complex environmental settings needs to be fully understood and taken into consideration through continuous monitoring programs.