The diversity and abundance of zooplankton in the Lake Victoria and Kyoga basins and their relationship to fish production

Biological diversity of an ecosystem is considered a reliable measure of the state of health of the ecosystem. In Uganda's large lakes, the Victoria and Kyoga, the past three decades have been characterized by profound changes in fish species composition following the introduction of the piscivorous Nile perch (Oguto-Ohwayo 1990). Over 300 haplochromine cichlid species comprising a wide range of trophic groups were lost along with a host of non-cichlid fishes which occupied virtually all available ecological niches and in the lakes (Witte 1992). A second major ecological event has been the gradual nutrient enrichment of the water bodies (eutrophication) from diffuse and point sources, while at the same time pollutants have also gained entrance into the water systems in pace with indusfrial development and human population increases in the lake basins. Eutrophication and pollution have drastically altered the physical and-chemical character of the water medium in which different fauna and flora thrive. In Lake Victoria these alterations have resulted in changes of algal species composition from pristine community dominated by chlorophytes and diatoms (Melosira etc) to one composed largely of blue-green algae or Cyanobacteria (Microcystis, Anabaena, Planktolyngbya etc) (Mugidde 1993, Hecky 1993).

Fish species diversity in the Victoria and Kyoga lake basins: their conservation and sustainable use

Introduction of exotic fish species especially the Nile perch Lates niloticus, is believed to be responsible for the decline of fish species diversity in lakes Victoria, Kyoga and Nabugabo.About 60% of the haplochromine cichlids are thought to have become extinct from L. Victoria due to predation by the Nile perch. However there are many lakes satelite to the lakes Victoria and Kyoga basins which still have fish fauna similar to that of the main lakes. many of the satellite lakes are separated from the main lakes in, which Nile perch was introduced by extensive swamps that provide a barrier to Nile perch .A survey was carried out in a number of these satelite lakes and an inventory made of existing fish species. Their distribution and relative abundances were also determined. The lakes studied included Nawampasa, Nakuwa,Kawi Lamwa Gigate, Nyaguo, Agu, Nabugabo. Kayanja, Kaytigi, Mburo, Kachera and Wamala.Some habitats within the main lakes Victoria and Kyoga, especially those with rocky outcrops· and macrophyte cover that provide refugia for endangered species from Nile perch,were also surveyed) Various stations along the River Nile were also sampled to quantify the fish species that are still resent. Kyoga minor lakes were found to have the highest number of fish species especially of haplochromine cichlids. Many haplochromine trophic groups that were thought to be extinct from 1. Victoria still occur in these lakes.!Some of the satellite lakes, especially lakes Kayugi, Mburo and Kachera still contain .healili populations of oreochromis. I esculentus that could be used as brood stock in fish farming. Many of these lakes should .I ( I therefore be protected for conservation offish species diversity

The diversity of amphibians, reptiles and mammals and their importance in the Victoria and Kyoga lake basins

The shore margins of Lakes in the Victoria basin are highly dented and mostly swampy, fringed by Papyrus and other wetland vegetation types important habitats for herpetofauna and wetland adapted mammals. Of recent, the extent of the 'wetland' has been extended in several places by the Water Hyacinth (Eichornia cryaseps). Ecologically, amphibians are important in many ways; they are mostly predators, acting as primary and secondary carnivores. Their prey consists mostly of insects, some of which are pests to crops or disease vectors. They are also inter-inked in food chains, often acting as food for other vertebrates, such as pigs, birds, snakes and sometimes man. Because of their ectothermic physiology, the life history and ecology of amphibians often differ markedly from that of birds or mammals (McCollough el ai, (992).Amphibians are known to be an easily recognisable taxon in given habitats; and populations are sometimes specialised within a narrow habitat. This makes it easy and practical to monitor changes in composition over time, given different onditions (Heyer el al 1994, Phillips 1990). Impacts on their habitat are reflected in changes in numbers and species diversity in a short time. These are some of the factors that have made amphibians to be recognised, nowadays, as good indicators of habitat change

Genetic status of selected fish taxa in relation to conservation of genetic and species diversity in the Victoria and Kyoga Lake basins

Cichlids are known for their explosive radiation especially in the African Great Lakes marked with a high level of lake endemism. These fishes have been characterized mainly along trophic and habitat differences, by variation in morphological structures such as teeth and jaws and by differences in body shape and coloration. Cichlids are important as a microcosm of macroevolution. The explosive radiation, young evolutionary scale, and the isolation of groups characterized with high levels of endemism and presence of living fossils makes the group important for evolutionary and genetic studies. Lake Victoria region cichlids which are isolated and relatively more recent in evolution were the last to be appreciated in their diversity. Recently Ole Seehausen has found scores of rock fishes in Lake Victoria which were up to then thought to be absent from the Lake and only known to occur in Lakes Malawi and Tanganyika. Greenwood put together the species groups of Lake Victoria, and later in the early 1980's revised the classification of haplochromine species to reflect the phyletic origin and interrelationship of the various groups in Lake Victoria region. Melan Stiassny has been interested in early evolution of cichlids while the likes of Paul Fuerst and Lees Kaufman and Axel Meyer have been interested and are working to explain the speciation mechanisms responsible for the explosive radiation and evolution of cichlids. Locally S.B Wandera and his student Getrude Narnulemo are spearheading the biodiversity and taxonomic studies of cichlids in Lake Victoria region

The biology and ecology of native non-cichlids in the Victoria and Kyoga lake basins

An overview of the biology and ecology of some of the constantly less important commercial species is given below. These included Bagrus docmac, Clarias gariepinus, Protopterus aethiopicus, Labeo victorianus, Barbus spp, Mormyrids, Synodontis spp, and Schilbe intermedius. The stocks of most of these species declined due to over-exploitation and introduction of non-native fishes especially Nile perch. A few of these taxa still survive in the main lake and others in satellite lakes. The current status of these species in the Victoria lake basin is not known but the available information provided some information on some habitat and other requirements of some of these originally important species of the Victoria lake basin.

Review of river fisheries valuation in West and Central Africa

This paper provides a review of the valuation of river fisheries in West and Central Africa. It is the general perception that, compared to the biological and ecological aspects of river fisheries, this particular subject area has received relatively little attention. Economic valuation is concerned with finding expression for what is important in life for human society. It should, therefore, be a central and integral part of government decision-making and policy. The review started with concepts and methods for valuation. Three main types of valuation techniques were identified: conventional economic valuations, economic impact assessments and socioeconomic investigations, and livelihood analysis. On the basis of a literature review, valuation information was then synthesized for the major regional river basins and large lakes, and also used to develop a series of national fisheries profiles. To supplement this broad perspective, a series of case studies are also presented, which focus in particular on the impact of changes in water management regime. Finally, the paper presents an assessment of the three main types of valuation methodology and a set of conclusions and recommendations for future valuation studies.

Review of river fisheries valuation in Central and South America

Unlike Africa and Asia, where a large part of the population are heavily dependent upon fishing for their livelihoods, fishing for a living in the interior of Central and South America (CSA) remains a marginal occupation for all but the most isolated of families. As such, the economics and management of fisheries on the continent have received little attention from within the continent and the rest of the world. This study shows that while a number of studies have been carried out on fishing in the region, they tend to be limited in their geographical focus and time scale. Although fishing of freshwater species may appear to be comparatively insignificant in the region, the rivers of CSA are very important. This report attempts to analyze the literature available on CSA river fisheries and attempts to draw out an economic value of these fisheries. It is divided into a number of sections. First, the authors describe the major river basins on the continent, characterize their fisheries, and place freshwater fisheries in CSA into a global context. Second, the authors provide a review of valuation techniques for fisheries and use this analytical framework to review the principal literature on freshwater fisheries in the region. Then they turn their attention to the economic impact of dams and water abstraction schemes, reviewing the available literature to ascertain how/if economic values are computed for the impact on fisheries. Finally, they offer some conclusions and recommendations on the direction for future studies of freshwater fisheries in CSA.

Summary report on water quantity and quality studies of Vancouver Lake, Washington

Vancouver Lake, located adjacent to the Columbia River and just north of the Vancouver-Portland metropolitan area, is a "dying" lake. Although all lakes die naturally in geologic time through the process of eutrophication,* Vancouver Lake is dying more rapidly due to man's activities and due to the resultant increased accumulation of sediment, chemicals, and wastes. Natural eutrophication takes thousands of years, whereas man-made modifications can cause the death of a lake in decades. Vancouver Lake does, however, have the potential of becoming a valuable water resource asset for the area, due particularly to its location near the Columbia River which can be used as a source of "flushing" water to improve the quality of Vancouver Lake. (Document pdf contains 59 pages) Community interest in Vancouver Lake has waxed and waned. Prior to World War II, there were relatively few plans for discussions about the Lake and its surrounding land area. A plan to drain the Lake for farming was prohibited by the city council and county commissioners. Interest increased in 1945 when the federal government considered developing the Lake as a berthing harbor for deactivated ships at which time a preliminary proposal was prepared by the City. The only surface water connection between Vancouver Lake and the Columbia River, except during floods, is Lake River. The Lake now serves as a receiving body of water for Lake River tidal flow and surface flow from creeks and nearby land areas. Seasonally, these flows are heavily laden with sediment, septic tank drainage, fertilizers and drainage from cattle yards. Construction and gravel pit operations increase the sediment loads entering the Lake from Burnt Bridge Creek and Salmon Creek (via Lake River by tidal action). The tidal flats at the north end of Vancouver Lake are evidence of this accumulation. Since 1945, the buildup of sediment and nutrients created by man's activities has accelerated the growth of the large water plants and algae which contribute to the degeneration of the Lake. Flooding from the Columbia River, as in 1968, has added to the deposition in Vancouver Lake. The combined effect of these human and natural activities has changed Vancouver Lake into a relatively useless body of shallow water supporting some wildlife, rough fish, and shallow draft boats. It is still pleasant to view from the hills to the east. Because precipitation and streamflow are the lowest during the summer and early fall, water quantity and quality conditions are at their worst when the potential of the Lake for water-based recreation is the highest. Increased pollution of the Lake has caused a larger segment of the community to become concerned. Land use and planning studies were undertaken on the Columbia River lowlands and a wide variety of ideas were proposed for improving the quality of the water-land environment in order to enhance the usefulness of the area. In 1966, the College of Engineering Research Division at Washington State University (WSU0 in Pullman, Washington, was contacted by the Port of Vancouver to determine possible alternatives for restoring Vancouver Lake. Various proposals were prepared between 1966 and 1969. During the summer and fall of 1967, a study was made by WSU on the existing water quality in the Lake. In 1969, the current studies were funded to establish a data base for considering a broad range of alternative solutions for improving the quantity and quality of Vancouver Lake. Until these studies were undertaken, practically no data on a continuous nature were available on Vancouver Lake, Lake River, or their tributaries. (Document pdf contains 59 pages)

Low streamflow in the Myakka River Basin Area in Florida

The Sarasota-Manatee area is a water-short area and the study was undertaken in 1963 in order to determine the storage capability and discharge rates of the Myakka water shed. It was found that many of the streams of the water shed were virtually dry during part of every year. However, the basins of the Myakka lakes, through which the river flows offer some storage potential, that if properly developed would provide a continuance drift of about seven million gallons of water per day of good quality water that would be high in color and temperature upon occasion. With reasonable treatment some of this water could be used to meet the present needs of the rapidly expanding coastal areas. (PDF contains 40 pages.)

Interim report on the hydrologic features of the Green Swamp area in Central Florida

The Green Swamp area in central Florida is another area where man is developing agricultural land from marginal land. Though the area is by no means as extensive as that of the Everglades, the present efforts for its development are similar to the early efforts for developing the Everglades in that many miles of canals and ditches have been constructed to improve the drainage. Lest the early mistakes of the Everglades be repeated, the Florida Department of Water Resources considered that an appraisal of the physical and hydrologic features of the area was needed to determine the broad effects of draining and developing the swamp. This reconnaissance provides information required by the State of Florida for determining its responsibility and policy in regard to the Green Swamp area and for formulating future plans for water management of the area. Some of the features that have been determined are: the amount of rainfall on the area; the pattern of surfacewater drainage; the amount and direction of surface-water runoff; the direction of ground-water movement; the interrelationship of rainfall, surface water, and ground water; the effects of improved drainage facilities'; and the effects of the hydrologic environment on the chemical quality of water of the area.(PDF contains 106 pages.)

Ichthyological ecoregions of Argentina

The Argentine Republic is situated in the southernmost portion of the American continent, occupying over 2,785,600 km2 not including the Antarctic territory. The country ranges from subtropical areas (21º46’S) to subantarctic regions (55º03’S), extending latitudinally over about 4,000 km. It possesses significant latitudinal and altitudinal variation (33º of latitudinal range, and heights from Bajo de San Julián in Santa Cruz province at 105 m below sea level, up to Mt. Aconcagua, 6,959 m over sea level), as well as two gradients of physical variability, extending in north-south and east-west directions. Owing to these features, the country presents a wide range of climates and soil types, being one of the countries with greatest diversity of biogeographical units (Lean et al., 1990, In: Bertonatti & Corcuera, 2000). There are four main hydrographic systems: Río de la Plata basin, the Atlantic and Pacific drainages, and several endorrheic systems. Within these basins, the ichthyofaunistic assemblage is well represented, with different magnitude in accordance with the different taxonomic groupings and regions considered. From an ichthyogeographic standpoint, and according to the works of Ringuelet (1975) and Arratia et al. (1983), Argentina is included in the Brasilic and Austral Subregions. The first of these is represented by two domains: the Andean Domain, comprising the southernmost portion of Titicaca Province, and the Paranensean Domain, including part of Alto Paraná and Paranoplatensean Provinces. The Austral Subregion is represented in Argentina by the Subandean-Cuyan and Patagonian Provinces. The present survey indicates that there are about 441 fish species in Argentina, distributed throughout the country; this number represents less than 10% of the total fish species occurring in the Neotropical Region. There is a recognizable trend of faunal impoverishment, both in North-South and East-West direction, reaching its maximum expression in the provinces of Tierra del Fuego (situated at approximately 52º30’S to 55ºS, and 65ºS to 68º50’W) and San Juan (approximately 28º50’S and 67ºW to 70º45’W), which have 4 and 5 fish species respectively. In north-south direction, one of the regional indicators of this phenomenon is the Salado river basin in Buenos Aires province, which constitutes the southern distributional boundary for the majority of the paranoplatensean ichthyofauna; 12 of the families occurring in the Paraná-Plata system are absent from this pauperized paranensean ichthyofaunal assemblage. Most of the continental fish fauna of Argentina belongs to the primary division of Myers (1949), while some elements are included in the secondary division and others in an amphibiotic or ‘marine penetration’ category. This ichthyofaunistic scope encompasses a wide range of morphological, biological, ecological and ethological types (benthic and pelagic, migrating and sedentary, haematophagous or parasites, annual species, inhabitants of plains or heights, estivation-adapted, etc.) inhabiting different regions within the national territory.

Monitoring hydrilla using two RAPD procedures and the Nonindigenous Aquatic Species database

Hydrilla ( Hydrilla verticillata (L.f.) Royle), an invasive aquatic weed, continues to spread to new regions in the United States. Two biotypes, one a female dioecious and the other monoecious have been identified. Management of the spread of hydrilla requires understanding the mechanisms of introduction and transport, an ability to map and make available information on distribution, and tools to distinguish the known U.S. biotypes as well as potential new introductions. Review of the literature and discussions with aquatic scientists and resource managers point to the aquarium and water garden plant trades as the primary past mechanism for the regional dispersal of hydrilla while local dispersal is primarily carried out by other mechanisms such as boat traffic, intentional introductions, and waterfowl. The Nonindigenous Aquatic Species (NAS) database is presented as a tool for assembling, geo-referencing, and making available information on the distribution of hydrilla. A map of the current range of dioecious and monoecious hydrilla by drainage is presented. Four hydrilla samples, taken from three discrete, non-contiguous regions (Pennsylvania, Connecticut, and Washington State) were examined using two RAPD assays. The first, generated using primer Operon G17, and capable of distinguishing the dioecious and monoecious U.S. biotypes, indicated all four samples were of the monoecious biotype. Results of the second assay using the Stoffel fragment and 5 primers, produced 111 markers, indicated that these samples do not represent new foreign introductions. The differences in the monoecious and dioecious growth habits and management are discussed.

Appraisal of water resources in the east central Florida region

The rapidly expanding population and economic growth in the seven counties of the East Central Florida Regional Planning Council as shown in Figure 1, herein called the East Central Florida Region or the Region, has resulted in increasing demands on its water resources. Although there is abundant water in the Region as a whole, the water in some areas of the Region is of unacceptable quality for most uses. As the population increases the demand for water will become much greater and the available supply may be reduced by pollution and increased drainage necessitated by urbanization and other land development- Ground-water supplies can be increased by capturing and storing water underground that now drains to the sea or evaporates from swamp areas. Research is needed, however, to develop artificial-recharge methods that are feasible and which will preserve or improve the quality of water in the aquifer. (PDF contains 57 pages)

New fish populations as evidence of climate chage in former dry areas of the Pampa Region ( Southern South America).

Water bodies located at 34º 58' S, 62º 58' W formed after 1980 by 30 % increasing rainfall during the last half century, were colonized by ten fish species which are a subset of the commonest species living in the pampasic lagunas. These new populations imply a displacement of the West of Pampasian fishes to areas of the western basins previously lacking fish.

Some effects of tropical storm Agnes on water quality in the Patuxent River estuary

A post Agnes study emphasizing environmental factors...weekly sampling at eight stations from 28 June to August 30, 1972. Spatial and temporal changes in the distribution of many factors, e.g., salinity, dissolved oxygen (DO), seston, particulate carbon and nitrogen, inorganic and organic fractions of dissolved nitrogen and phosphorus, and chlorophyll a were studied and compared to earlier extensive records. Patterns shown by the present data were compared especially with a local heavy storm that occurred in the Patuxent drainage basin during July 1963. Some interesting correlations were observed in the data. (PDF has 39 pages.)