Showing papers in "Journal of Aquatic Sciences in 1999"

Haematological Changes in the Mudfish, Clarias gariepinus (Burchell) Exposed to Malachite Green

Abstract: The effect of sublethal concentrations of malachite green on blood compositions of the mudfish, Claris gariepinus (Burchell) was investigated under static bioassays during a 10 week exposure periods. Concentrations of malachite green used were 0.00 (control), 5.00, 10.00, 15.00, 20.00 and 25.00 µg1-1. The exposure led to anaemic response in the fish, this response was observed to be time and dose dependent. There was significant reduction in the neutrophils of the fish exposed to 15.00, 20.00 and 25.00 µg1-1. of the toxicant. The implications of these results were discussed with a suggestion of the total on the use of malachite green in aquaculture. Journal of Aquatic Sciences Volume 14, April 1999, pp. 37-42 KEY WORDS: Haematological, mudfish, Clarias gariepinus, malachite green.

Flora and Fauna of Abiala Creek, Niger Delta, Nigeria

Abstract: Abiala creek is a typical aquatic weed infested creek in the Niger Delta Area of Nigeria. Examination of the aquatic vegetation revealed seven weed species dominated by Eichhornia crassipes (Mart.) Solm - Laub. The presence of these aquatic weeds negatively affected the plankton species diversity in the creek. The weed-free areas of the creek were qualitatively and quantitatively richer in plankton than the weed-infested areas. The aquatic weeds created an adverse environmental condition, which forced fish to migrate to the weed-free areas of the creek. The preponderance of male to female specimens and near absence of juvenile fishes was a reflection of the negative influence of the presence of the aquatic weeds on fish population structure. The predominating fish families - Polyteridae, Clariidae, Anabantidae and Channidae were discovered to have accessory respiratory organs. Journal of Aquatic Sciences Volume 14, April 1999, pp. 61-65 KEY WORDS: Eichhornia crassipes, aquatic weeds, plankton, diatom, Niger Delta, Nigeria.

Fertilization of Earth Ponds. I: Effects on Physico-Chemical Characteristics and Eutrophication of Pond Water and Soil

Abstract: Various biomanipulation strategies, using inorganic and organic fertilizer to improve oligotrophic conditions were carried out in earth ponds in Central Scotland U.K. over a period of one year. Replicate ponds were treated with low and high phosphorus (LP, HP) high phosphorus and nitrogen (HPN), low and high chicken manure (LC, HC) high chicken and cow manure (HCC) and tow untreated controls (CTRL). The effects of treatments on physio-chemical parameters of the pond water and soil suitable for trout culture was also evaluated along with primary production. There was generally remarkable improvement in eutrophic condition with respect to water and soil qualities. Water pH rose steadily from 7.0 - 7.5 at pre-manipulation state to 7.73 - 8.39 in the CTRL, LP and HPN in response to liming and fertilization. Soil pH was generally acidic in the range, 5.80 - 6.64 in both organic and inorganic fertilization. Differences in nutrient (ammonia, nitrate and phosphate) concentrations were consistent with fertilizer application. Nitrite showed an initial decline in CTRL, LP and HP, but there was an upsurge in HPN, which significantly varied (P Journal of Aquatic Sciences Volume 14, April 1999, pp. 5-12 KEY WORDS: Fertilization, earth pond, water, soil and eutrophication.

Fertilization of Earth Ponds. III: Effects on Benthic Macro Invertebrates and Ecological Inter-Relationship with Aquatic Macrophytes

Abstract: Organic fertilizers in form of cow and chicken manure were applied in oligotrophic or unproductive pond water over a period of one year to stimulate the production of benthic macro invertebrates for the benefit of trout culture, while maintaining adequate water quality. Development of aquatic macrophytes during both inorganic and organic fertilization in all the ponds was also evaluated with respect to the mutually beneficial relationship or `trade off' between the macrophytes and benthos. For the organic fertilization, replicate ponds were treated with low and high chicken manure (LC, HC), combination of high chicken and cow manure (HCC) and untreated controls (CTRL). The results showed that the application of HC and combination of HCC gave the highest numbers and biomass of benthos. The dominant groups encountered were in the order: Oligochaeta > Chironomidae > Asellidae > Sialidae > Hirudinea > Mollusca. Total abundance, biomass and dry weight production estimates of the benthos during the culture period were in the range, 3.5 - 134.0 x 103 ind. m-2; 26.0 - 113. gm-2 and 14.7 - 70.0g dry wt m-2 respectively. Throughout the inorganic and organic fertilization trials, pond 2, which was at various times treated with high phosphorus (HP) fertilizer and HCC had the most abundant macrophytes, with Elodea canadensis, Lemna mino, Glyceria fluitans and Alisma plantago-aquatica dominating, especially in the warm summer periods of July - August. The development of aquatic macrophytes in some ponds favoured production of some benthos, presumably due to greater foliage surface area that influenced plankton development, which are good sources of diet for the benthos. The results are discussed with respect to the mutually beneficial relationship or `trade-off' between the macrophytes and benthos, nutrient circulation and pond ecosystem stability. Journal of Aquatic Sciences Volume 14, April 1999, pp. 19-28 KEY WORDS: Fertilization, earth pond, macro invertebrates, macrophytes and ecological inter-relationship

Fertilization of Earth Ponds. II: Effects on Plankton Communities

Abstract: A study of the effects of slurry inorganic and organic of fertilizers on the production of phyto-and zooplankton in earth ponds was conducted in Central Scotland, U.K. over a period of one year. For the inorganic fertilization, replicate ponds were treated with low and high phosphorus (LP, HP), high phosphorus and nitrogen (HPN); while the organic fertilization replicated treatments were low and high chicken (LC, HC) manure and combination of high chicken and cow (HCC) manure. Each of the fertilization programmes had two untreated controls (CTRL), without fertilizer. All the Cyanophyceae (blue-green algae) than the CTRL, but HPN, produced vastly more algae that the others. The response pattern of Dinophyceae (dinoflagellates) was low. The organic trials responded to treatments, but more positively to HC and HCC in the zooplankton, and dominant genera encountered in both trials were Cladocera, Rotifera and Copepoda. The role of decaying plankton and organic manure as sources of detritus and carbon, providing nutrients in a vicious circle for optimum biological production is discussed in the light of food web sustainability in semi-intensive and intensive aquaculture systems. Journal of Aquatic Sciences Volume 14, April 1999, pp. 13-18 KEY WORDS: Fertilization, earth pond, phytoplankton, zooplankton and detritus.

Acute Toxicity and Gill Morphology of Oreochromis niloticus (Trewavas) Exposed to Rogor

Abstract: The acute toxicity of Rogor(R) was determined for juvenile bony fish, Oreochromis niloticus in 96-h static bioassays. The fish treated with Rogor(R) showed abnormal behaviour characterised by restlessness, uncoordinated movements, loss of equilibrium, air gulping, loss of buoyancy, periods of quiescence and death. The 96-h LC50 of Rogor(R) for O. niloticus was 0.018 (0.015.022) ml/1. Rogor(R) treatment caused epithelial detachment in the primary and secondary lamellae. It was suggested that osmoregulatory and respiratory incapacitation through mucus accumulation and histologic damage are the major causes of fish mortality following Rogor(R) exposure. Journal of Aquatic Sciences Volume 14, April 1999, pp. 1-4 KEY WORDS: Rogor, toxicity, gill, morphology, Oreochromis niloticus

Effects of Kidney Bean, Phaseolus vulgaris Meal on the Growth Performance, Feed Utilization and Protein

Abstract: Growth, feed utilization and protein digestibility in the fingerlings of the Nile tilapia, Oreochromis niloticus (mean weight 1.36 + 0.05 g) fed diets containing varying levels of the kidney bean, Phaseolus vulgaris were investigated under laboratory conditions. The kidney bean was incorporated at separate levels of 60, 40, 20 and 0% (control). The feeding period lasted for 8 weeks. There was no mortality recorded in all the various treatments, and the fish feed avidly throughout the feeding period. In general, the best growth and feed utilization results were obtained in fish fed the control diet, however, results obtained with the 60% kidney bean diet were satisfactory. Weight gain of the fish fed the control diet was 92s.02% , that fed on the 60% kidney bean diet was 71.22%, while that fed on the 20% kidney bean diet had the least weight gain value of 16.67%. Protein digestibility values in the control and 60% kidney bean diets were 85.04% and 81.04% respectively. There was no evidence of excessive fat or carbohydrate deposition in the fish muscle tissues after the feeding period. Journal of Aquatic Sciences Volume 14, April 1999, pp. 55-60 KEY WORDS: Growth, feed indices, digestibility, Tilapia, kidney bean

Studies on the Biology of Larvae of Clarias albopunctatus (N. & L.): Effect of Different Diets on the Growth and Survival of Larvae

Abstract: Clarias albopunctatus larvae, collected from the laboratory hatchlings were on the 4th day of lie, subjected to six different diet consisting of A - Plankton, B - Egg Yolk, C - Beef liver, D - Milk Powder, E - Crayfish trash and F - Soya bean meal. The experiment was maintained at 27.5 ± 5 0oC. Larval weight measurements before the experiment and later once in two days, were obtained, Larvae were fed to satiation, 4 times daily. Dead larvae were siphoned ad counted twice daily. The experiment ended on the 14th day and the respective groups were compared on the basis of growth rates, survival rates and food conversion ratios larvae fed on plankton diet were significantly higher than those fed on other diet. Larvae fed on soya bean meal had the lowest mean growth rates, survival rates and food conversion ratios. Survival rates of larvae fed on diets C and D; C and E; E and F were not significantly different between themselves but significantly differed from either A or B diet. Variations on the result suggests that larval age requires a period of live food feeding and this gradually will become replaced by artificially compounded feeds. Journal of Aquatic Sciences Volume 14, April 1999, pp. 29-32 KEY WORDS: Diets, growth, survival, Clarias albopuctatus

Microbial Flora of Partially Processed Periwinkles (Tympantotonus fuscatus) from Local Markets in Port Harcourt, Nigeria

Abstract: A survey of microbial flora of partially processed periwinkles (Tympanotonus fuscatus) sold in six markets in Port Harcourt was undertaken for twelve weeks. Results show that all samples of periwinkles were contaminated with Staphylococcus aureus, Bacillus sp., Escherichia coil, Staphepidermidis sp., Micrococcus sp., Pseudomonas sp., and Klebsiella sp. Staphylococcus aureus was the most predominant 24.9% while Klebsilella sp. was the least 5.80%. The occurrence of Staphylococcus aureus, Bacillus sp., and Escherichia coil is indicative of a high pathogenicity and health hazard in consuming periwinkles. The need to critically re-examine our public health standards in the markets is advocated. Journal of Aquatic Sciences Volume 14, April 1999, pp. 51-54 KEY WORDS: Microbial flora, periwinkles flesh, Port Harcourt, Markets.

The Effects of Temperature on Egg Development African Mayfly Povilla adusta (Ephemeroptera: Polymitarcidae)

Abstract: Egg masses were prepared from a packet of eggs of Povilla adusta Navas and incubated in the laboratory at constant temperatures and hatching success expressed by the logarithmic equation log Y = 0.14T + 1.42 (r2 = 0.028, P > 0.1). Hatching success was highest (84.85%) in eggs kept outside the incubator at laboratory temperature (33.2oC) followed by those incubated at 35oC (76.52%) and 30oC (65.46%) in that order. No hatching occurred in eggs incubated at 15oC, 20oC and 25oC. Minimum and mean incubated periods were the same at temperature at which eggs hatched. Hatching duration was short (1 - 2 days), which indicates synchronous hatching. A comparison of these results with previous findings suggests that Povilla adusta is warm adapted and as such, is confined to the tropical region in Africa where water temperatures are higher. Journal of Aquatic Sciences Volume 14, April 1999, pp. 47-50 KEY WORDS: Mayflies, temperature, egg development, distribution, Africa.

The Effects of Refinery Effluent of the Chlorophyll a and Gross Primary Productivity of River Rido

Abstract: The effect of Kaduna Refinery effluent discharge on the chlorophyll a and gross primary productivity of river Rido was studied for 12 months at 3 stations in the river. Station 1 is the clean water station not affected by the discharge; stations 2 & 3 are the polluted area. The values for chlorophyll a and gross primary productivity were low in all the stations. Station 1 showed significantly higher (P Journal of Aquatic Sciences Volume 14, April 1999, pp. 43-46 KEY WORDS: Discharge, chlorophyll a, gross primary productivity, effluents, polluted.