Ecological and Socio-economic Impacts of Ecohydrological Interventions on the Wetlands along the Southeastern Shore of Lake Tana, Ethiopia
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Date
2020-10-18
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Addis Ababa University
Abstract
Information regarding the ecological and socio-economic impacts of ecohydrology based intervention approach in the wetland ecosystem plays an indispensable role in increasing biodiversity, improve water quality and enhance ecosystem services. Although ecohydrological solutions have been proposed by various studies for immediate, nature based, management to prevent degradation from imminent developments, a comprehensive study on the impacts of ecohydrology intervention in relation to biological, physico-chemical and socio-economical aspects are limited. Such information is very important for the management of degraded shore wetlands of Lake Tana. Thus, the aim of this study was to investigate the impacts of ecohydrological intervention in relation to physical, chemical and biological attributes and assess the most common socio-economic benefits of the wetlands in Lake Tana shore. Ecological and socioeconomic impacts of ecohydrological intervention on the wetlands in the shore of Lake Tana were studied in November 2019 and April 2020. Physico-chemical data were measured on each sampling point. Sediment and water samples were measured and analyzed onsite and in the laboratory and most of the Physico-chemical parameters were significantly different (p<0.05) across the sampling sites. The quadrat/transect method was employed to collect macrophyte and macroinvertebrate data. Quantitative characteristics of macrophyte sampling were conducted using transect and quadrat method along vegetation and water depth gradients. A total of 24 quadrats of 1m×1 m size were employed using the species-area curve method for all sampling sites. A total of 12 major macrophytes species were recorded from all sampling sites. The abundance of macrophytes varied between sampling sites and season and this might be attributed to the differences in protection status, human disturbances, physico-chemical parameters and level of awareness of the community. Based on the Shannon diversity index (H' = 0), the Agid kirgna wetland could be grouped under the least diverse followed by Gedromesk wetland (H' = 1.00) and Gumetirs wetland (H' = 1.24). A total of 975 macroinvertebrate individuals belonging to 15 families were collected using a D-frame net from all sampling sites during the study period. Based on the biological indices, H' = 2.39 and HFBI=4.68, the Gumetirs wetland might be grouped under a good ecological condition. Both phytoplankton and zooplankton samples were collected using a 15μm mesh size plankton net. A total of 23 phytoplankton and 9 zooplankton taxa were collected. Numerical density and diversity of zooplankton and phytoplankton taxa varied along the sampling sites, habitats and seasons which could be linked with food availability, degree of disturbance and physico-chemical conditions. Qualitative and quantitative data were collected from 90 households head (HHDs) on several variables through structured questionnaire, interview and observation to assess the socio-economic benefits of the wetlands. Overall results of this study confirmed that biological, physico-chemical conditions and wetland benefits were associated with the intensive human activities carried out in and around the wetlands, and level of awareness of the local communities. Therefore, emphasis should be given to the factors which may lead to the degradation of wetland resources within and its catchment especially recession farming, overharvesting, overgrazing and invasion of water hyacinth. Immediate ecohydrology based intervention approaches should be implemented to conserve and minimize further degradation and ensure sustainable livelihoods of wetlands along the shore of Lake Tana.
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Abundance, Biodiversity, Ecohydrology, Human Disturbances, Lake Tana, Socio-Economics, Wetland Conditions, Wetland Degradation