The species composition and production of the phytoplankton community of the Shesher and Welala floodplain Wetlands, on the eastern side of Lake Tana, were studied during four seasons from July 2009 to May 2010. We in...The species composition and production of the phytoplankton community of the Shesher and Welala floodplain Wetlands, on the eastern side of Lake Tana, were studied during four seasons from July 2009 to May 2010. We investigated the spatial and temporal dynamics of phytoplankton, densities, biomass, in relation to physico-chemical conditions. Gross and net primary production was studied at one site in each Wetland. Temperature, dissolved oxygen, conductivity, Secchi-disc depth, nitrate, phosphate and silicate concentrations showed significant temporal variation (p 0.05). Thirty six phytoplankton genera/species, belonging to 7 higher taxa were identified. The Chlorophyta dominated the phytoplankton community and contributed 42% - 53 % of the total observed phytoplankton numbers. Average phytoplankton biomass (chlorophyll a content) over four seasons ranged from 9 - 121 μg.l-1 in Shesher and from 27 - 206 μg.l-1 in Welala, whereas the average gross primary production over three seasons was 10.5 in Shesher and 7.7 mg.O2l-1d-1 in Welala. The peak concentration of chlorophyll a was observed in the pre-rainy season, which coincided with a bloom of Microcystis spp. Both Shesher and Welala Wetlands are very productive and have a good water quality but they are threatened by low water inputs since in the summer of 2009 the construction of a dam by local people and facilitated by local officials prevented overflow from Ribb River into the Wetlands. We conclude that the good water quality, the relative high water temperature and high primary productivity make the two Wetlands suitable for culture based fisheries and/or aquaculture, but a wise water resource management is crucially important.展开更多
The frequent occurrence of extreme flood events in the late 1990s and the past decade has brought about an ongoing debate on the relationships between wetland resources, wetland ecosystem services, and human developme...The frequent occurrence of extreme flood events in the late 1990s and the past decade has brought about an ongoing debate on the relationships between wetland resources, wetland ecosystem services, and human development and livelihoods of communities in the Dongting Lake area. This paper is prepared for analysing the best practices in wise-use and sustainable management of wetland and their socioeconomic benefits in Polder Xipanshanzhou in Dongting Lake. The quantitative （monetary values） and qualitative socioeconomic data of 1683 samples from questionnaire surveys during 2000 to 2008 were used for this study, of which 1173 were obtained in Polder Xipanshanzhou. Five conclusions are drawn from the study： （i） the community-based alternative activities and wise-use in Polder Xipanshanzhou after ＂Returning Farmland to Lake＂ （RFL） resulted in more income, increased well-being, reduced vulnerability to food shortage, poverty and flooding, and more sustainable use of the natural resource base; （ii） women, elder farmers, and low-income groups benefited much more from these activities; （iii） livelihood continued to improve as compared with that when the project started in 2000, and project participating households earned more income and owned more properties than non-project households. Even after the external funding stopped in 2001, its positive accumulated effects have still been significantly contributing to the improvement of livelihoods of this community; （iv） social structures within Polder Xipanshanzhou have been evolving in a positive way, community-based grass-roots organizations have emerged and developed well, and the capacities of community-based participatory co-management, self-governing and self- development, as well as local awareness of environmental issues have been improving, which attract more local people to be interested in such wise-use activities; and （v） the success can be attributed to the mobilization of local communities, favorable national policies, Public-P展开更多
文摘The species composition and production of the phytoplankton community of the Shesher and Welala floodplain Wetlands, on the eastern side of Lake Tana, were studied during four seasons from July 2009 to May 2010. We investigated the spatial and temporal dynamics of phytoplankton, densities, biomass, in relation to physico-chemical conditions. Gross and net primary production was studied at one site in each Wetland. Temperature, dissolved oxygen, conductivity, Secchi-disc depth, nitrate, phosphate and silicate concentrations showed significant temporal variation (p 0.05). Thirty six phytoplankton genera/species, belonging to 7 higher taxa were identified. The Chlorophyta dominated the phytoplankton community and contributed 42% - 53 % of the total observed phytoplankton numbers. Average phytoplankton biomass (chlorophyll a content) over four seasons ranged from 9 - 121 μg.l-1 in Shesher and from 27 - 206 μg.l-1 in Welala, whereas the average gross primary production over three seasons was 10.5 in Shesher and 7.7 mg.O2l-1d-1 in Welala. The peak concentration of chlorophyll a was observed in the pre-rainy season, which coincided with a bloom of Microcystis spp. Both Shesher and Welala Wetlands are very productive and have a good water quality but they are threatened by low water inputs since in the summer of 2009 the construction of a dam by local people and facilitated by local officials prevented overflow from Ribb River into the Wetlands. We conclude that the good water quality, the relative high water temperature and high primary productivity make the two Wetlands suitable for culture based fisheries and/or aquaculture, but a wise water resource management is crucially important.
基金National Natural Science Foundation of China (grant number: 30670374)National Basic Research Program of China (973 Program): Ecosystem Services and Ecological Safety of the Major Terrestrial Ecosystems of China (grant number: 2009CB421106)WWF (World Wide Fund for Nature) International Collaboration Program: Wetland Ecosystem Assessment and Management in Dongting Lake (grant number: CN0088.03-YB01/02/03/04)
文摘The frequent occurrence of extreme flood events in the late 1990s and the past decade has brought about an ongoing debate on the relationships between wetland resources, wetland ecosystem services, and human development and livelihoods of communities in the Dongting Lake area. This paper is prepared for analysing the best practices in wise-use and sustainable management of wetland and their socioeconomic benefits in Polder Xipanshanzhou in Dongting Lake. The quantitative （monetary values） and qualitative socioeconomic data of 1683 samples from questionnaire surveys during 2000 to 2008 were used for this study, of which 1173 were obtained in Polder Xipanshanzhou. Five conclusions are drawn from the study： （i） the community-based alternative activities and wise-use in Polder Xipanshanzhou after ＂Returning Farmland to Lake＂ （RFL） resulted in more income, increased well-being, reduced vulnerability to food shortage, poverty and flooding, and more sustainable use of the natural resource base; （ii） women, elder farmers, and low-income groups benefited much more from these activities; （iii） livelihood continued to improve as compared with that when the project started in 2000, and project participating households earned more income and owned more properties than non-project households. Even after the external funding stopped in 2001, its positive accumulated effects have still been significantly contributing to the improvement of livelihoods of this community; （iv） social structures within Polder Xipanshanzhou have been evolving in a positive way, community-based grass-roots organizations have emerged and developed well, and the capacities of community-based participatory co-management, self-governing and self- development, as well as local awareness of environmental issues have been improving, which attract more local people to be interested in such wise-use activities; and （v） the success can be attributed to the mobilization of local communities, favorable national policies, Public-P
