Heavy metals concentrations in water, sediment, water hyacinth (Eichhornia crassipes) and Frillfin Goby (Bathygobius soporator, Cuvier and Valenciennes, 1837) from Ologe Lagoon, Southwest, Nigeria

The level of heavy metals in water, sediment, water hyacinth (Eichhornia crassipes) and frillfin goby (Bathygobius soporator) from Ologe Lagoon and its tributaries were monitored because of the importance of the water bodies to the socio-economic well-being of the rural population. Physico-chemical parameters and selected heavy metals (Fe, Zn, Cu, Pb and Cd) contents of water, sediment, E. crassipes and B. soporator from six sampling stations in Ologe Lagoon were measured monthly from February to November, 2015. The range of concentration of heavy metals in sediment are: Fe (454±112-2756±1213mg/kg), Zn (3.89±3.08-18.7±6.83mg/kg), Cu (7.68±5.65-36.8±16.9mg/kg), Pb (6.24±2.56-11.2±4.45mg/kg) and Cd (0.42±0.17-0.92±0.42mg/kg). Heavy metal concentration in E. crassipes were 68.5±16.5-987±86.8mg/kg, 13.2±6.40-162±46.2mg/kg, 0.56±0.25-6.54±1.45mg/kg, 5.06±2.41-12.2±4.71mg/kg and 0.28±0.22-1.21±0.49mg/kg for Fe, Zn, Cu, Pb and Cd respectively. The concentrations of heavy metals in the muscle of B. soporator in wet season were: Fe, 8.30±2.29 mg/kg; Zn, 0.78±0.28 mg/kg; Cu, 16.20±6.20 mg/kg; Pb, 2.21±0.33mg/kg; Cd, 0.16±0.05mg/kg while in dry season, they were: Fe, 27.19±7.28 mg/kg; Zn, 24.47±6.27 mg/kg; Cu, 0.18±0.16 mg/kg; Pb, 1.72±0.07mg/kg; Cd, 0.19±0.03mg/kg. Hardness and turbidity showed significant (p<0.05) spatial variation. Concentrations of Fe, Zn and Cu in sediment varied significantly (p<0.05) among the sampling sites but Pb and Cd did not. The heavy metal content of water hyacinth from the six sampling stations exhibited significant (p<0.05) spatial variation except Cd. The concentrations of Fe, Zn and Cu in B. soporator were significantly (p<0.05) affected by season but Pb and Cd were not. Although only Pb exceeded the FAO/WHO maximum permissible limits in the tissue of B. soporator, regular monitoring of Ologe Lagoon is advocated in order stern further deterioration of the ecosystem and to protect the rural population that depend on it for sustenance

The effects of dichlorvos (2, 2 - dichlorovinyl phosphate (DDVP)) induced stress on the growth of fingerlings of Clarias gariepinus (Burchell, 1822)

This study was conducted to determine the effects of dichlorvos ~9 2, 2 - dichlorovinyl dimethyl phosphate (DDVP)~0 on the growth of Clarias gariepinus fingerlings. The experiment was conducted in two phases: the first phase involved the exposure of the fish to different concentrations ~9 0.00 (control), 0.4ppm, 0.5ppm, 0.6ppm, 0.7ppm, 0.8ppm, 0.9ppm, 1.0ppm, 1.1 ppm and 1.2ppm~0 of dichlorvos for four days. The second phase was a recovery process in which the fish that survived from the first phase were introduced into clean, dechlorinated, toxicant-free water and were fed at 3% of their body weight for 12 weeks. The change in weight was measured every fortnight and the feed fed was adjusted to accommodate the change in weight. The highest values for weight gain, percentage weight gain, specific growth rate and average daily weight gain occurred in the control and these values were significantly (p<0.05) higher than the values of these parameters recorded in the other treatments. The range of values of weight gain, percentage weight gain, specific growth rate and average daily weight gain are 6.76 ~c 3.01-18.45 ~c 8.90g, 69.45 ~c 18.52 - 105.52 ~c 33.67%, 1.54 ~c 0.33 - 2.08 ~c 0.46%/day and 0.48 ~c 0.21 - 1.21 ~c 0.65g respectively. Based on the results of this study, the exposure of fingerlings of Clarias gariepinus to dichlorvos ~9 2, 2- dichlorovinyl dimethyl phosphate (DDVP)~0 affected the growth of the fish. Therefore, the use of dichlorvos on stored grains should be regulated because uncontrolled usage could cause mortality and impairment of growth in fish if the pesticide gets washed into water bodies inhabited by fish

An overview of the challenges and prospects in developing an aquaculture industry in Lagos State, Nigeria

Macroeconomic growth and the development of sustainable business activities are interrelated. In Lagos State, aquaculture is a marginal economic activity thriving mainly on a semi-intensive level. Notwithstanding the available potentials for the development of successful commercial aquaculture enterprises in the state, the transformation to a full-flagged industry continues to be undetermined by certain critical factors. Feasible development strategies may be sought in increasing all stakeholders' capacity in the formulation of policies, plans and regulations, a complete separation of aquaculture from the capture fisheries in administrative structure and policy; the adoption of precautionary approach; provision of economic incentives to enhance private investments and increase output,respectivel

Survival, growth and feed utilization of the reciprocal hybrids of Clarias gariepinus (Burchell, 1822) and Heterobranchus bidorsalis (Geoffroy, 1809) in concrete tanks

An experiment was conducted to determine the survival rate, fertilization rate, growth performance and feed utilization of the reciprocal hybrids of Clarias gariepinus and Heterobranchus bidorsalis. Two genetic crosses were made: C. gariepinus (male) x H. bidorsalis (female)(Clariabranchus) and H. bidorsalis male x C. gariepinusmale (Heteroclarias. The experiment was divided into two phases; artificial propagation of the fish species using synthetic hormone and rearing the fry for 14 days; and rearing the 14 days old fry for 35 days. In the first phase of the experiment, survival of frys were estimated in each experimental unit (genetic cross) while in the second phase, growth and nutrient utilization were investigated. The result revealed that the highest %fertilization, hatching rate and %survival occurred in H. bidorsalisfemale x C. gariepinus male (Heteroclarias) and the differences were significant (p < 0.05). Percentage weight gain and specific growth rate were significantly (p < 0.05) higher in Clariabranchus than Heteroclarias. Based on the result of this study, reciprocal hybrids of Clarias gariepinus and Heterobranchus, bidorsalis is recommended for commercial aquacultural practices

A prelimnary study of diet in the juvenile gorean snapper, Lutjanus goreensis (Valenciennes, 1830) from Five Cowrie Creek, Lagos, Nigeria

Diet of the juvenile Gorean snapper, Lutjanus goreensis from Five Cowrie Creek was investigated between April 2008 and January 2009. Analyses of 184 specimens by numerical (NO), frequency of occurrence (FO) and geometric index of importance (GII) methods, respectively revealed a moderately high proportion (47.83%) of stomachs with food or prey. Shrimps and crabs constituted more than 80 % of total prey items. Other dietary components included lobsters, stomatopods, whole fish and fish parts. Similarly, analysis of diet composition by size - groups also indicated a predominance of the shrimps and crabs over all other prey items. In conclusion, L. goreensis can be described as a top-level carnivore feeding almost exclusively on epibenthic crustaceans in the juvenile stage

Growth response of north African catfish fry to organic and inorganic fertilizers

Background. Fertilizer application is considered a viable low-cost method of sustainable aquaculture production. This study was carried out to investigate the growth response of north African catfish, Clarias gariepinus (Burchell, 1822), fry to inorganic- (NPK) and organic (cow dung and poultry dropping) fertilizers. Materials and methods. Catfish fry (0.05–0.06 g) were transferred for six weeks into a 0.13-m deep, culture units of the surface area of 0.135 m2. Each culture unit was treated with either cow dung +NPK (T1), poultry dropping (T2), cow dung + poultry dropping (T3), control with no fertilizer (T4), NPK + poultry dropping (T5), cow dung (T6), NPK + cow dung + poultry dropping (T7), and NPK (T8). Results. Fertilizer type was found to influence the quality and quantity of plankton, which in turn determined the growth and well-being of catfish fry. The best weight increase was recorded in T1 (1.37 ± 1.01 g) followed by T2 (0.49 ± 0.31 g), and then T7 (0.40 ± 0.23 g). The survival rate in T1 (100%) and T2 (60%) were the highest relative to the control (T4) (87%). Dissolved oxygen, pH, and temperature of culture water were variously affected by the treatments. Conclusion. The results indicate that mixture of NPK and either cow dung or poultry droppings would adequately cater for the growth needs of C. gariepinus fry before feeding on compounded diet