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.

Catalogue des ennemis naturels des macrophytes flottants Pistia stratiotes, Salvinia molesta et Eichhornia crassipes

We identified from bibliographical review and field observations fourty two species composed essentially of molluscs and insects. These animals attack floating plants such as E. crassipes, P. stratiotes and S. molesta. They indifferently consume or destroy the aquatic plants except N. bruchi, N. eichhorniae and S. albiguttalis which specifically attack E. crassipes. N. putchellus, L. guinaicus and P. africana graze preferably P. stratiotes; C. salviniae, C. singularis and P. acuminata consume only Salvinia molesta.

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.

Abundance of harbor porpoise (Phocoena phocoena) in three Alaskan regions, corrected for observer errors due to perception bias and species misidentification, and corrected for animals submerged from view

Estimating the abundance of cetaceans from aerial survey data requires careful attention to survey design and analysis. Once an aerial observer perceives a marine mammal or group of marine mammals, he or she has only a few seconds to identify and enumerate the individuals sighted, as well as to determine the distance to the sighting and record this information. In line-transect survey analyses, it is assumed that the observer has correctly identified and enumerated the group or individual. We describe methods used to test this assumption and how survey data should be adjusted to account for observer errors. Harbor porpoises (Phocoena phocoena) were censused during aerial surveys in the summer of 1997 in Southeast Alaska (9844 km survey effort), in the summer of 1998 in the Gulf of Alaska (10,127 km), and in the summer of 1999 in the Bering Sea (7849 km). Sightings of harbor porpoise during a beluga whale (Phocoena phocoena) survey in 1998 (1355 km) provided data on harbor porpoise abundance in Cook Inlet for the Gulf of Alaska stock. Sightings by primary observers at side windows were compared to an independent observer at a belly window to estimate the probability of misidentification, underestimation of group size, and the probability that porpoise on the surface at the trackline were missed (perception bias, g(0)). There were 129, 96, and 201 sightings of harbor porpoises in the three stock areas, respectively. Both g(0) and effective strip width (the realized width of the survey track) depended on survey year, and g(0) also depended on the visibility reported by observers. Harbor porpoise abundance in 1997–99 was estimated at 11,146 animals for the Southeast Alaska stock, 31,046 animals for the Gulf of Alaska stock, and 48,515 animals for the Bering Sea stock.

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.

Charts for the rapid estimation of percentages of plants and/or animals in samples

The need to estimate percentages and/or numbers occurs frequently during practical research work; accurate but rapid estimates can be useful when planning research programmes. Charts are provided that may be used as a visual aid to estimating numbers of animals/plants in a specific situation, for example, the number of fish fry in a subsample from a hatchery tank, or the percentage composition of a sample such as the percentage algal cover in a pond.

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.

Perspectives from agriculture: advances in livestock breeding - implications for aquaculture genetics

In this paper we present livestock breeding developments that could be taken into consideration in the genetic improvement of farmed aquaculture species, especially in freshwater fish. Firstly, the current breeding objective in aquatic species has focused almost exclusively on the improvement of body weight at harvest or on growth related traits. This is unlikely to be sufficient to meet the future needs of the aquaculture industry. To meet future demands breeding programs will most likely have to include additional traits, such as fitness related ones (survival, disease resistance), feed efficiency, or flesh quality, rather than only growth performance. In order to select for a multi-trait breeding objective, genetic variation in traits of interest and the genetic relationships among them need to be estimated. In addition, economic values for these traits will be required. Generally, there is a paucity of data on variable and fixed production costs in aquaculture, and this could be a major constraint in the further expansion of the breeding objectives. Secondly, genetic evaluation systems using the restricted maximum likelihood method (REML) and best linear unbiased prediction (BLUP) in a framework of mixed model methodology could be widely adopted to replace the more commonly used method of mass selection based on phenotypic performance. The BLUP method increases the accuracy of selection and also allows the management of inbreeding and estimation of genetic trends. BLUP is an improvement over the classic selection index approach, which was used in the success story of the genetically improved farmed tilapia (GIFT) in the Philippines, with genetic gains from 10 to 20 per cent per generation of selection. In parallel with BLUP, optimal genetic contribution theory can be applied to maximize genetic gain while constraining inbreeding in the long run in selection programs. Thirdly, by using advanced statistical methods, genetic selection can be carried out not only at the nucleus level but also in lower tiers of the pyramid breeding structure. Large scale across population genetic evaluation through genetic connectedness using cryopreserved sperm enables the comparison and ranking of genetic merit of all animals across populations, countries or years, and thus the genetically superior brood stock can be identified and widely used and exchanged to increase the rate of genetic progress in the population as a whole. It is concluded that sound genetic programs need to be established for aquaculture species. In addition to being very effective, fully pedigreed breeding programs would also enable the exploration of possibilities of integrating molecular markers (e.g., genetic tagging using DNA fingerprinting, marker (gene) assisted selection) and reproductive technologies such as in-vitro fertilization using cryopreserved spermatozoa.

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.

Ex-situ conservation of the germplasm of aquatic organisms

This paper summarizes some of the major issues relating to ex-situ conservation of the germplasm of aquatic organisms and gives examples of some current activities and future possibilities.