291 resultados para Aquatic ecotoxicity


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Bujagali hydropower dam construction is now completed and a reservoir behind the dam has been created, extending all the way up to Kalange-Makwanzi, an upstream transects. During the 10th monitoring survey-April 2012, a third transect was established in the mid of the reservoir where it runs up to 30 m deep and sampled similarly as at the two original sampling transects, Kalange-Makwanzi and Buyala-Kikubamutwe for comparative purposes. This monitoring survey No. 12 undertaken between 25th and 30th April 2013 is the third one to be conducted after completion of construction of Bujagali Hydropower Dam. Two pre-construction baseline surveys in April 2000 and April 2006 were conducted and during construction phase, eight monitoring surveys (September 2007, April 2008, April 2009, October 2009, April 2010, September 2010, April 2011, September 2011) were conducted. Since 2009 biannual monitoring surveys have been conducted at an upstream and a downstream transect of the BHPP with emphasis on the following aspects: water quality determinants, biology and ecology of fishes and food webs, fish stock and fish catch including economic aspects of catch and sanitation/vector studies (bilharzias and river blindness). In the post-construction monitoring surveys, the assessments of algae, zooplankton and benthic macro-invertebrates which had been restrained since April 2008 were also included.

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The survey covered by this report was undertaken between 3rd and 7th April 2009 as a follow-up on the during construction surveys. Two pre-construction baseline surveys were undertaken in April 2000 and April 2006. During the construction phase which started in 2007, three surveys including the current one have been undertaken i.e. in September 2007, April 2008 and the present one, in April 2009. Unlike in all previous surveys in which monitoring was conducted at one transect upstream and three downstream transects, in the current survey, two transects, one upstream and the other,downstream of the BHPP were sampled with emphasis on the following aspects: 1. water quality determinants 2. biology and ecology of fishes and food webs 3. fish stock and fish catch including economic aspects of catch and 4. sanitation/vector studies (bilharzias and river blindness)

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The status of fish stocks in a water body at any one time is a function of several factors affecting the production of fish in that water body. These include: total number (abundance) and biomass(weight) present, growth (size and age), recruitment (the quantity of fish entering the fishery) including reproduction, mortality which is caused by fishing or natural causes, Other indirect factors of major importance to the status of the stocks include production factors (water quality and availability of natural food for fish), the life history parameters of the different species making up the stocks (e.g. sex ratios, condition of the fish, reproductive potential (i.e. fecundity) etc), Changes in fish stocks do occur when any of the above listed factors directly influence aspects of growth, reproduction and mortality and therefore, numbers and standing stock (biomass). In the exploited fisheries, major research concerns regarding stocks relate to the listed factors especially: estimates of stock abundance/biomass, the quantity of fish being caught,where the fish are caught, which species are caught (relative abundance)when the fish are caught, how the fish are caught. The balance between stock abundance and amount of fish caught provides the basis for intervention. Due to the diverse characteristics of the physical water environment, fishes are in general, not evenly distributed throughout a water body. Shallow and vegetated areas tend to support higher abundance and diversity of fish species. In addition, seasonal variations in fish abundance are so strong that fluctuations in catch have to be expected at fish landings.

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The CGIAR Research Program on Aquatic Agricultural Systems (AAS) is collaborating with partners to develop and implement a foresight-based engagement with diverse stakeholders linked to aquatic agricultural systems. The program’s aim is to understand the implications of current drivers of change for fish agri-food systems, and consequently food and nutrition security, in Africa, Asia and the Pacific. Partners include the Global Forum on Agricultural Research (GFAR), the Forum for Agricultural Research in Africa (FARA) and the African Union’s New Partnership for Africa’s Development (AU-NEPAD). A key part of the program was a participatory scenario-building workshop held in July 2015 under the theme of "futures of aquatic agricultural systems and implications for fish agri-food systems in southern Africa." The objectives for the workshop were (i) to engage local stakeholders in exploring plausible futures of aquatic agricultural systems, and (ii) to broker and catalyze collaborative plans of action based on the foresight analysis. This report presents technical findings from the workshop. The CGIAR Research Program on Aquatic Agricultural Systems (AAS) is collaborating with partners to develop and implement a foresight-based engagement with diverse stakeholders linked to aquatic agricultural systems. The program’s aim is to understand the implications of current drivers of change for fish agri-food systems, and consequently food and nutrition security, in Africa, Asia and the Pacific. Partners include the Global Forum on Agricultural Research (GFAR), the Forum for Agricultural Research in Africa (FARA) and the African Union’s New Partnership for Africa’s Development (AU-NEPAD). A key part of the program was a participatory scenario-building workshop held in July 2015 under the theme of "futures of aquatic agricultural systems and implications for fish agri-food systems in southern Africa." The objectives for the workshop were (i) to engage local stakeholders in exploring plausible futures of aquatic agricultural systems, and (ii) to broker and catalyze collaborative plans of action based on the foresight analysis. This report presents technical findings from the workshop.

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The results reported on were from a monitoring survey No. 9 undertaken between 9th and 12th September 2011 during construction period of the Bujagali Hydropower Project (BHPP). Two pre-construction, baseline surveys in April 2000 and April 2006 were conducted and so far, during construction phase of the project, eight monitoring surveys have been undertaken i.e. in September 2007, April 2008, April 2009, October 2009, April 2010, September 2010, April 2011 and the present one, in September 2011. Since 2009 biannual monitoring surveys have been conducted at an upstream and a downstream transect of the BHPP with emphasis on the following aspects: water quality determinants biology and ecology of fishes and food webs fish stock and fish catch including economic aspects of catch and sanitation/vector studies (bilharzias and river blindness)in addition to the above mentioned studies, a soil pH survey was undertaken on 15th October 2011 in the area behind the reservoir whose filling started a week earlier. The findings of pH status in the catchment of the dam are also contained in this report.

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The mobile water hyacinth, which was produced in growth zones, especially Murchison bay, was mainly exported to three sheltered storage bays (Thruston, Hannington and Waiya). Between 1996 and May 1998, the mobile form of water hyacinth occupied about 800 ha in Thruston bay, 750 ha in Hannington bay and 140 ha in Waiya bay). Biological control weevils and other factors, including localised nutrient depletion, weakened the weed that was confined to the bays and it sunk around October 1998. The settling to the bottom of such huge quantities of organic matter its subsequent decomposition and the debris from this mass was likely to have environmental impacts on biotic communities (e.g. fish and invertebrate), physico-chemical conditions (water quality), and on socio-economic activities (e.g. at fish landings, water abstraction, and hydro-power generation points). Sunken water hyacinth debris could also affect nutrient levels in the water column and lead to reduction in the content of dissolved oxygen. The changes in nutrient dynamics and oxygen levels could affect algal productivity, invertebrate composition and fish communities. Socio-economic impacts of dead sunken weed were expected from debris deposited along the shoreline especially at fish landings, water abstraction and hydropower generation points. Therefore, environmental impact assessment studies were carried out between 1998 and 2002 in selected representative zones of Lake Victoria to identify the effects of the sunken water hyacinth biomass.

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Proliferation of invasive aquatic weeds has developed into a major ecological and socio economic issue for many regions of the world. As a consequence, inference on where to target control and other management efforts is critical in the management of aquatic weeds (Ibáñez et al., 2009). Notwithstanding, aquatic systems in Uganda in general and in the basins of Lakes Victoria and Kyoga in particular, have fallen victims to aquatic weeds invasion and subsequent infestation. If these aquatic weeds infestations are to be minimized and their impacts mitigated, management decisions ought to be based on up-to-date data and information in relation to location of infestation hotspots. Aquatic systems in the basins of the two production systems are important sources of livelihoods especially from fish production and trade yet they are prone to infestation by aquatic weeds. Thus, the invasion and subsequent infestation of aquatic ecosystems by aquatic weeds pose a major conservation threat to various aquatic resources (Catford et al., 2011; Kayanja, 2002). This paper examines the extent to which aquatic weeds have infested aquatic ecosystems in the basins of Lakes Victoria and Kyoga. The information is expected to guide management of major aquatic weeds through rational allocation of the scarce resources by targeting hotspots.

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Weeds are plants growing in environments where they are undesirable. Aquatic weeds in fresh waters are nuisance or noxious plants growing in association with water in lakes, impoundment, rivers, canals, wetlands, etc. Some waterweeds cause very big financial loss through the socio economic, environmental and ecological impacts they inflict; and through the effort and expense required for their control. Other waterweeds are simply nuisance plants that cause minimal impacts. This paper is intended to introduce aquatic weeds outlining their characteristics, the main socio-economic and environmental impacts associated with them, and the control strategies often applied for their management.

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Uganda is rich in aquatic resources. Up to 17 % of the country's surface area is covered by Aquatic systems comprising five major lakes; Victoria, Albert, Kyoga, Edward, George, about 160 minor lakes, an extensive river and stream system, dams and ponds. These aquatic systems are associated with extensive swamps

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The poster explains the effects of aquatic plants to fisheries and how they can be controlled.

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*Table of Contents* Research & farming techniques Nursery rearing of Puntius goniotus: A preliminary trial K.N. Mohnta, J.K. Jena & S.N. Mohanty Artemia enrichment and biomass production for larval finfish and shellfish culture A.S. Ninawe Vembanad Lake: A potential spawner bank of the giant freshwater prawn Macrobrachium rosenbergii on the southwest coast of India Paramaraj Balamurugan, Pitchaimuthu Mariappan & Chellam Balasundaram Seed production of mud crab Scylla serrata at the Rajiv Gandhi Center for Aquaculture, Tamil Nadu, India Mohamed Shaji, Emilia T. Quinitio, Thampi Samraj, S. Kandan, K. Ganesh, Dinesh Kumar, S. Arulraj, S. Pandiarajan, Shajina Ismail and K. Dhandapan. Sustainable aquaculture Fish wastes in urban and suburban markets of Kolkata: Problems and potentials Kausik Mondal, Anilava Kaviraj & P.K. Mukhopadhyay People in aquaculture Peter Edwards writes on rural aquaculture: Farming carps in leased ponds by groups of poor women in Chandpur, Bangladesh Aquatic animal health Lymphocystis disease and diagnostic methods in China Jing Xing, Xiuzhen Sheng & Wenbin Zhan Asia-Pacific Marine Finfish Aquaculture Network Mesocosm technology advances grouper culture in northern Australia Elizabeth Cox, Peter Fry & Anjanette Johnston

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*Table of Contents* Sustainable aquaculture Peter Edwards writes on rural aquaculture: Small-scale pond culture in Bangladesh. People in aquaculture Community based aquaculture - issues and challenges H.K. De and G.S. Saha. Aquaculture as an action programme: An exercise in building confidence and self worth. B. Shanthi, V.S. Chandrasekaran, M. Kailasam, M. Muralidar, T. Ravisankar,.C. Saradad and M. Krishnan The STREAM Column: Transforming policy recommendations into pro-poor service provision Graham Haylor. Research & farming techniques. Grow out of juvenile spotted Babylon to marketable size in earthen ponds II: Polyculture with seabass. S. Kritsanapuntu, N. Chaitanawisuti, W. Santhaweesuk and Y. Natsukari Asia-Pacific Marine Finfish Aquaculture Network. Influence of economic conditions of importing nations and unforeseen global events on grouper markets. Sih Yang Sim. Present status of hatchery technology for cobia in Vietnam. Nhu Van Can. Report on grouper hatchery training course in Indonesia. Nguyen Quoc Thai. Aquatic animal health. Biosecured and improved penaeid shrimp production through organic nursery raceway system in India. Felix. S. and M. Samaya Kannan. Management of monogenean parasites in brackishwater finfish. K.P. Jithendran, M. Natarajan and I.S. Azad. Vembanad Lake: A potential spawner bank of the giant freshwater prawn Macrobrachium rosenbergii on the southwest coast of India. Paramaraj Balamurugan, Pitchaimuthu Mariappan & Chellam Balasundaram.

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(121 p.)