Effect of different feeding levels on the production of Heterobranchus bidorsalis in outdoor concrete tanks

Fry of Heterobranchus bidorsalis (mean weight, 0.03g) were fed at 10, 20, 30, 40 or 50% of their body weight (bw)/day in outdoor concrete tanks in New Bussa, Nigeria. The fry attained the highest average weight of 6.66g in 10 weeks when fed at 40% bw/day. Feed conversion ratio ranged from 2.13 to 9.65, the protein efficiency ratio from 1.33 to 5.93. Results indicated that H. bidorsalis are efficient feed converters. Feed intake was significantly different (p<0.05) between the treatments, specific growth rate (SGR), daily growth rate (DGR), production and average weight gain indicated that 40% of fish biomass was the optimum feeding level

Ecology and fishery in the Cross River Estuary - a research project

A literature review of 50 titles including nearly all relevant publications ensures adequate basis on the present level of knowledge. The proposal includes (a) the determination of the biozoenosis and selected environmental factors, and (b) of fishery and stock data of the main fish and shellfish species. The ecological research studies physical and chemical variables of the estuarine waters (flow velocity and direction, water temperature, conductivity, pH, dissolved oxygen, salinity, nutrients such as ammonium, nitrite, phosphate, silicate, pollutants such as hybrocarbons, pesticides and heavy metals, biochemical oxygen demand, chemical oxygen demand), plankton (bacterio-phyto-and zooplankton), benthos, sediment. The fishery biological and fishery investigations include: number of villages and fishermen, number of boats and gears by type, length and weight data of the main fishery objects with concentration on the shrimps, species and numbers of fish parasites. The ecological variables were monitored at fixed stations on sections in the Cross-River Estuary, Calabar and Great Kwara Rivers two times per month during spring and neap tides. The fishery biological and fishery variables were obtained during spring and neap tide too. For the determination of the detailed methodology the ecological and fishery part of the progeamme should be started with frame surveys based on a larger number of stations. These frame surveys should be repeated from time to time. Both parts of the programme are based on three years duration. It seems already appropriate to continue the work with selected representative stations, villages and variables in form of a long-term data chain

A review of the biology, ecology and management of Scirpus Olneyi. Volume 1: An annotated bibliography of selected references

This annotated bibliography of selected literature on Olney's three7square (Scirpus olneyi Gray )compiled basically for two reasons: 1) to assist a task force in its pursuit of an explanation for the substantial reduction in marsh acreage at the Blackwater National Wildlife Refuge in Dorchester County, Maryland, and 2) to serve as the author's foundation for the initiation of ecological research on this species as partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Botany Department of the University of Maryland. Both purposes are directly related in that the Author's research will be of use to the task force, along I with its other technical information and research results, in under-standing and possibly correcting the marshland loss problem at the Refuge. (PDF contains 100 pages)

Aspects of ecology of Owena reservoirs: implication on fish production

The article gives physical description of Owana reservoir, Nigeria. The reservoir was chemically and thermally stratified partial mixing of the water was observed during the rains. The concentration of major ions in the water showed distinct peculiarities. The captions (Na super(+), K super(+)Ca super(H),Ca super(Z), Mg super(++)) SO sub(4) super(2-) were relatively low. The water had high dissolved oxygen, it was acidic and also had low values of alkalinity, conductivity and total dissolved solids. About 61 plankton taxa belonging to 21 species were identified. The reservoir supports a commercial fishery of about fifteen fishermen with about fifteen species of fish caught daily with the aid of traps set and cast nets. Effective management of the lake will enhance fish production

Feeding and waste management strategies in the culture of Clarias gariepinus

Nutrient digestibility and amino acid availability were assessed in sharp-toothed catfish, Clarias gariepinus, fingerlings fed diets containing soyabean flour (SF) - Poultry meat meal (PMM) blends (25:75. 50:50, and 75:25) and 0.5 of 1.0%, Cr sub(2)0 sub(3). There was agreement between the pattern of overall protein digestibility and average amino acid availability despite the variability in individual amino acid availability the best dry matter, lipid and protein digestibility coefficients, and amino acid availability values were obtained with diets containing 0.5% Cr sub(2)0 sub(3). Chromic Oxide inclusion level appeared to affect nutrient availability. Increased marker level resulted into decreased nutrient digestibility coefficients. Similarly, these diets generated lower fecal crude protein than those with 1.0% Cr sub(2)0 sub(3). However, the latter group recorded higher protein retention efficiency. Dry mailer and lipid of diets containing more soyabean flour seemed to be more digestible than those of poultry meat meal. Similar trend was observed for the apparent availability of the amino acids. This investigation has indicated that low level of marker was better in digestibility study. Utilization of more SF than PMM in the diets of this catfish was more beneficial and should be encouraged in the feed industries producing catfish diets towards a better feed and waste management strategies in this aquaculture operation

Social Organisation of the Short-finned Pilot Whale, Globicephala macrorhynchus, with Special Reference to the Comparative Social Ecology of Delphinids

As a contribution to the understanding of comparative social trends within the cetacean family Delphinidae, a 22-month study was conducted on the shortfinned pilot whale, Globicephala macrorhynchus, which has been suggested to have a unique social system in which males and females in the same group are related and mating occurs outside of the group. The individual identification of 495 pilot whales, analysed in daily group association patterns, allowed identification of 46 pods. They were classified as productive or non-productive based on the presence or absence of immature animals. Productive pods were a significantly larger, although 12% of them lacked adult males. Two classes of whales (residents and visitors) were defined by patterns of occurrence,suggesting differential patterns of habitat use. Resident pods occasionally travelled together (41% of all groups) and associations between age and sex classes showed that in mixed-pod groups, the highest ranked associations of the reproductive females were with males from other pods, while within pods, adult males and females associated less. During summer, the proposed peak conception period, pilot whale groups were significantly larger and contained individuals from a significantly greater number of pods. These findings support the hypothesis that males and females mate when associating with individuals from other pods. A comparative analysis of sexual dimorphism, brain size, and testes size, habitat, prey and group size within the 17 delphinid genera identified a correlation between sexual dimorphism and body size, but relative measures of brain size and testes size did not correlate with broad ecological or social classifications. However, a comparison of three delphinid societies identified two distinct male mating systems: males of the small, mono-morphic Tursiops truncatus live in age/sex segregated groups and mate with a number of discrete female communities. Males in the large sexually dimorphic Glob icephala spp. and Orcinus orca mate with associated female pods and yet remain with their female kin. This corresponds to the avunculate social system described in some human societies. It could evolve from a promiscuous mating system where there is little guarantee of paternity and where males that live with their kin increase their inclusive fitness.

Food and feeding habits of Heterotis niloticus from River Kaduna floodplain

A total of 61 Heterotis niloticus specimen were examined and evaluated to determine the food and feeding habits using the frequency of occurrence, point and dominance methods. The specimens had mean standard length of 27.09 plus or minus 4.73cm, total length of 33.40cm body weight of 90-900g. The gut length ranges from 34-104cm while the gut weight range from 2.79-130g. It was observed that the fish fed mostly on plankton with rotifers and polyscysits having the highest number of frequency and dominant value with mean value of 43.03 plus or minus 4.12 and 11.73 plus or minus 1.15, 37.45 plus or minus 3.27 and 8.32 plus or minus 0.38 respectively. Arcella had the least mean frequency of occurrence of 3.27 plus or minus 17. Amoeba sp had the least mean dominance value of 7.06 plus or minus 50 and Aphnocapsa sp had the least mean frequency of occurrence of 1.10 plus or minus 0.29 and Navicula sp had the least mean dominance value of 4.31 plus or minus 1.11. Heterotis niloticus of River Kaduna flood plain is therefore considered to be predominantly planktivorous

The impact of varying nutrient regimes in earthen freshwater ponds on the comparative ecology of diurnally occurring candidate live feeds

The daytime composition and relative abundance of zooplankton species were studied in three treatments of two replicate earthen ponds each with nutrient sources and water replenishment regimes. Treatment -A (200m super(2) surface area supplied 900kgha super(-1) pig manure only). Treatment -B (200m super(2) surface area supplied 70kgha super(-1) month super(-1) pig manure, 50kgha super(-1) month super(-1) N.P.K. [15:15:15] and 30kgha super(-1) month super(-1) Urea) and Treatment-C (1500m2 surface area supplied 1150kgha super(-1) month super(-1) commercial grade 40% crude protein compounded feed). Water replenishment for Treatment A was daily tidal deluge from the New Calabar River while that for treatment B and C was from column-well and occasional rains. No zooplankton species were recovered from the pig-manure only treatment (A) while only Diffugia constricta and Difflugia urceolata were the two protozoans that occurred together in treatments B (combined fertilization) and C (compounded feed only) in contrast, Difflugia acuminate and three rotifers, Collurella uncinata, Diurella stylata and Keratella quadrata occurred only treatment B. similarly, Arcella arenaria, Arcella costata, Centropyxis aculeate, Difflugia pyriformis, Branchionus calyciflorus, Lepadella patella, Polyarthra trigla and Onchocanmptus mohammedi were recovered from treatment C. Arcella costata was the most abundant zooplankton in the entire experiment, while Arcella arenaria was very abundant in treatment C, Collurella uncinata was very abundant in treatment B. The inference is that combined fertilization of earthen freshwater ponds tend to be more suitable for the culture of rotifers such as Brachionus calyciflorus, popular in fish larva nursery, while those supplied compounded feed could be used to produce protozoans where desirable

Aquatic ecology, economy and society: the place of aquatic ecology in the sustainability agenda

This article explores aspects of sustainability and the importance of sustainable development, including the place of the crucially important resource of fresh water and of freshwater ecosystems. It examines the treatment of natural resources by the economic system that underpins global business, outlines some progress towards more sustainable approaches to business, and recommends steps to re-establish science as the driver of wise policies that contribute to sustainable development.

Symposium on Llangrose Lake: the ecology and conservation of a large nutrient-rich lake in South Wales

This paper summarises a meeting which discussed the ecology and conservation of Llangorse Lake in South Wales. The meeting was organised by the British Ecological Society (Aquatic Ecology Group), in association with the Countryside Council for Wales (CCW), Brecon Beacon National Park Authority (BBNPA) and Environment Agency Wales. It took place on 22 October 1998.

The ecology of Bassenthwaite Lake (English Lake District)

Bassenthwaite Lake is, in many ways, different from the other major lakes in the English Lake District: it is the most northerly, the shallowest, has the largest catchment and the shortest mean retention time. There is also considerable temporal variation in lake level. This article summarises the limnological features of Bassenthwaite Lake, the catchment and physical characteristics before describing the water chemistry, phytoplankton, macrophytes, zooplankton, invertebrates, fish, mammal and invertebrate population. The authors then describe the ecological pressures faced by Bassenthwaite Lake such as nutrients, sediments and introduced species.

Interrelated contributions to freshwater science over 78 years: A guide to published work from the Freshwater Biological Association, Institute of Freshwater Ecology and Centre for Ecology and Hydrology, 1929-2006

This article introduces a new listing of published scientific contributions from the Freshwater Biological Association (FBA) and its later Research Council associates – the Institute of Freshwater Ecology (1989–2000) and the Centre for Ecology and Hydrology (2000+). The period 1929–2006 is covered. The authors offer also information on specific features of the listing; also an outline of influences that underlay the research, and its scientific scope.

Monitoring feeding of great whales by ingested acoustic temperature transmitter

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Structure of the limbs and its significance for the ecology and systematics of the family Chydoridae. [Translation of: Voprosy Gidrobiologii, p385, 1965]

For an explanation of the dynamics of numbers of chydorids, appearing a massive group in the littoral of fresh water bodies, the structure of the limbs of 29 species was studied.