The diversity and ecological role of protozoa in fresh waters

Protozoa feed on and regulate the abundance of most types of aquatic microorganisms, and they are an integral part of all aquatic microbial food webs. Being so small, aerobic protozoa thrive at low oxygen tensions, where they feed (largely unaffected by metazoan grazing) on the abundance of other microorganisms. In anaerobic environments, they are the only phagotrophic organisms, and they live in unique symbiotic consortia with methanogens, sulphate reducers and non-sulphur purple bacteria. The number of extant species of protozoa may be quite modest (the global number of ciliate species is estimated at 3000), and most of them probably have cosmopolitan distributions. This will undoubtedly make it easier to carry out further tasks, e.g. understanding the role of protozoan species diversity in the natural environment.

The relationship between aquatic macrophytes and water quality in Nta-Wogba Stream, Port Harcourt, Nigeria

An empirical survey of macrophytes distribution and biomass from four stations, along Nta-wogba stream in Port Harcourt, Nigeria, was conducted between April and December 2007, to quantify the relationship between biomass, in stream nutrients and dissolved ions. The correlation analysis indicated that the biomass of the aquatic macrophytes under consideration, Einochloa pyramidalis; Diplazum sammatii; Cyperus difformis; Alternathera sessilis and Ludwigia decurrens were significantly (P<0.05) related to the nutrients: sulphate, ammonium; nitrate, and phosphate in all the stations. The measurement of total dissolved solid, which is correlated to ionic concentrations and turbidity, provided a rough indication of in stream light availability.

A comparative study of consumption rates and preference for some species of aquatic plants by Tilapia rendalli

The daily consumption rates and preference of juvenile Tilapia rendalli for some macrophytes, Ceratophyllum demersum, Lagarosiphon major, Najas pectinatas and Valisneria aethiopica were determined. Fish were offered single macrophyte diets to determine daily consumption and a mixture of the 4 macrophytes in equal quantities to determine selection. Consumption rates were 821.50 mg, 829.05 mg, 940.00 mg and 2293.53 mg per fish per day, respectively. The differences in consumption rates were significant. Preference was shown for V.aethiopica, whilst C.demersum was least selected. Fish fed on single species lost weight whereas those fed on a variety of macrophytes gained in weight.

Strengthening governance across scales in aquatic agricultural systems

Aquatic agricultural systems in developing countries face increasing competition from multiple stakeholders operating from local to national and regional scales over rights to access and use natural resources—land, water, wetlands, and fisheries-essential to rural livelihoods. A key implication is the need to strengthen governance to enable equitable decision-making amidst such competition, building capacities for resilience and transformations that reduce poverty. This paper provides a simple framework to analyze the governance context for aquatic agricultural system development focused on three dimensions: stakeholder representation, distribution of power, and mechanisms of accountability. Case studies from Cambodia, Bangladesh, Malawi/Mozambique, and Solomon Islands illustrate the application of these concepts to fisheries and aquaculture livelihoods in the broader context of intersectoral and cross-scale governance interacti

Aquatic Agricultural Systems: Annual report

The program on aquatic agricultural systems (AAS) aims to change the way the CGIAR engages with aquatic agricultural systems and the poor and vulnerable communities who depend upon them. To do so the program has focused on three primary lines of work in its first six months: (i) preparing for implementation of the program in focal countries and geographical hubs; (ii) harnessing the best of earlier and ongoing research that contributes to the science themes of the program and which we wish to see expanded and integrated into the program as it develops; (iii) establishing innovative governance and management arrangements that will guide and implement the program. This report summaries the achievements and reviews the progress of the AAS program.

Assessment of the impact of aquatic resources research by ICLARM: scope and methodologies

The importance of quantifying the economic returns to investments in aquatic resources research together with the social, environmental and institutional impacts of such investments is widely recognized among ICLARM's donors, trustees and beneficiaries. As with other Consultative Group on International Agricultural Research (CGIAR) centers, ICLARM is being asked to provide specific accounts of the outputs of its research and their impact on farms and on fisheries, including their socioeconomic impact. Such impact information has become a necessary, though not sufficient, basis for setting priorities and allocating resources for research for the CGIAR centers. This paper discusses the types and methods of impact assessment relevant to ICLARM's work. A three-pronged assessment approach is envisaged to capture the full range of impacts: 1) ex ante assessment for research priority setting; 2) assessment prior to dissemination or adoption along with monitoring and evaluation; and 3) ex post impact assessment. It also discusses the objectives and scope for operational impact assessment of ICLARM's research.

Impact pathway analysis for research planning: the case of aquatic resources research in the WorldFish Center

In line with its mandate of poverty reduction and sustainable development, the WorldFish Center is orienting its research towards high impact scientific activity. Identifying such activities is the task of prospective impact assessment, in turn based on impact pathway analysis. The paper describes a framework for analyzing benefits from aquatic resources research, the relevant research categories, pathways to impact by category, and indicators along each pathway that can be estimated in order to quantify probable research impact.

CGIAR aquatic research priorities revisited: a case for a higher priority for reservoir-lake system research

The case presented in this article clearly indicates that reservoir and lake resource systems, reservoirs in the Asian context lakes plus reservoirs in the African context, have been given a lower priority than deserved.

Genetic enhancement and conservation of aquatic biodiversity in Africa

There is a pressing need to enhance fish production in Africa through improved farm management and the use of improved fish breeds and/or alien species in aquaculture while at the same time conserve the aquatic genetic diversity. This paper presents the outcome of the Expert Consultation on Biosafety and Environmental Impact of Genetic Enhancement and Introduction of Improved Tilapia Strains/Alien Species in Africa held in Nairobi, Kenya on 20-23 February 2002. The main topics discussed were status of aquaculture in Africa and the role of genetic enhancement; potential benefits and risks involved in introduction of genetically improved strains and/or alien species with specific reference to tilapias; existing policies and legislation for the conservation of biodiversity, their strengths and weaknesses; capacity for undertaking genetic enhancement research and implementation of policies for the conservation of aquatic biodiversity.

Bioethics and biotechnology

This paper examines the practice and products of biotechnology from the viewpoint of bioethics, looking at four cases where aquatic biotechnology and bioethics intersect. The four cases applied are: Case 1. Genetic modification of animals; Case 2. Genetically Modified Organisms (GMO) as food; Case 3. Environmental applications of GMOs; Case 4. Intellectual property production for GMOs and DNA sequences.

Aspects of phosphorus pollution from aquaculture

Phosphorus is an essential element for living organisms and exists in waterbodies as dissolved and particulate forms. Phosphorus is required for optimum growth, feed efficiency, bone development and maintenance of acid-base regulation in fish. The presence of high concentration of phosphates in water may indicate presence of pollution as it may accelerate plant growth and disrupt the aquatic ecosystem thereby benefiting certain species and altering species diversity in affected areas. Eutrophication of waterbodies is often correlated with the phosphorus loading into the environment and aquaculture has been identified as one of the sources of phosphorus pollution. Details of the impacts of eutrophication is given in Bernhardt (1981). Phosphorus must be provided in fish feed because of its low concentration in water. Studies made in Europe and Northern America have revealed a phosphorus surplus in most commercial feeds which is above actual requirements; or is supplied in a form which is unavailable to the fish. Surplus phosphorus is excreted, while unavailable phosphorus is passed out in the feces. Discharge of phosphorus from fish farms and hatchery effluents have caused phosphorus pollution in Nordic countries, North America and Europe. This article examines the path of phosphorus pollution, quantification/prediction of phosphorus load from aquaculture and remedial measures.

Down to earth thoughts on conserving aquatic genetic diversity

A discussion is presented on the topic of maintaining genetic diversity in aquatic ecosystems, considering the various threats caused by irreversible damage or loss to the environment. The current situation in aquaculture and future prospects regarding the conservation and protection of endangered species are outlined, describing the case of tilapias in Africa as one particular example of fish conservation.