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Ecological assessment of Cheffa Wetland in the Borkena Valley, northeast Ethiopia: Macroinvertebrate and bird communities

Ecological Indicators (Impact Factor: 2.89). 01/2012; 15:63-71. DOI: 10.1016/j.ecolind.2011.09.011

ABSTRACT A comparative study of macroinvertebrates and bird communities was undertaken to assess the ecological
integrity and human impact in Cheffa Wetland, northeastern Ethiopia. The study was undertaken from
February to May 2010. Physicochemical parameters of the water, birds, macroinvertebrates and human
impact classes were assessed at 10 sites in the wetland exposed to different anthropogenic activities. We
have compared Shannon index of diversity of macroinvertebrates and birds along with different habitat
classes. Multivariate statistics were used to extract the main driving forces for changes in macroinvertebrate
and bird community patterns out of a complex data set. Subsequently, we compared the diversity
indices of the macroinvertebrate and bird communities for the detection of human impacts. A total of
2789 macroinvertebrates belonging to 34 families in 10 orders were collected and 3128 birds belonging
to 57 species recorded. Macroinvertebrates belonged to five different orders: Hemiptera (seven families),
Coleoptera (five families), Odonata (five families), Gastropoda (seven families) and Diptera (five families),
exceeding 77% of the overall sample. Abundance and diversity of the bird and macroinvertebrate communities
were related mainly to concentrations of DO, nitrate and chloride, habitat conditions, and human
disturbances. Of the 57 species of birds recorded, the cattle egret (Bubulcus ibis), white-faced whistling
ducks (Dendrocygna viduata), Egyptian goose (Alopochen aegyptiacus) and spur-winged lapwing (Vanellus
superciliosus) were the most abundant. The physicochemical variables showed great variation among
sites. The results revealed that human interference in wetland may result in serious ecological imbalances
in the natural life cycle and impact on human welfare. Long-term studies are required to predict changes
in wetland ecology and population dynamics, with the objective of developing appropriate measures by
federal, regional and local stakeholders to ensure wetland restoration and sustainability.

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    ABSTRACT: Biotic indices are widely applied for conservation and management of aquatic resources since they allow water resources monitoring agencies to get insight in complex biological data and yield policy relevant information. Despite the worldwide popularity of biotic indices, little information on their use and applicability in Eastern Africa is available. Here, we develop a multimetric index based on macroinvertebrates to assess the ecological condition of natural wetlands in Southwest Ethiopia. Index development was based on a dataset of 222 samples collected during two consecutive years from 63 sites located at eight different wetlands. We used physico-chemical and hydro-morphological variables (land use pattern, habitat alteration, hydrological modification and chemical water quality) to classify sites as reference or degraded. We tested a total of 58 potential metrics representing various aspects of macroinvertebrate assemblages including family richness, composition, tolerance measures and presence and abundance of functional feeding groups. Metrics were selected for the development of a final index based on their sensitivity in discriminating reference from impaired sites, strength of correlation with the anthropogenic disturbance gradient, chemical measurements, and the degree of redundancy. Metrics retained for the final index were:overall family richness, family richness of Ephemeroptera, Odonata and Trichoptera (EOT), and percentage of filterer–collectors. The final index, derived from the sum of three metric scores, was divided into five water quality classes (very bad, bad, moderate, good and very good). Our final multimetric macroinvertebrate index (MMI) distinguished well between reference and impaired wetland sites and showed a significant negative response to a gradient of disturbances (R2 = 0.86, p < 0.05). Moreover, it classified a validation dataset accurately with a correctly classified instances of 80% and a Cohen’s Kappa value of 0.6. This MMI can be considered as a robust and sensitive tool that can be applied to evaluate the ecological condition of natural wetlands in Ethiopia, where wetland resources are under high pressure as a result of agricultural activities such as grazing and urbanization.
    Ecological Indicators 01/2013; 29:510-521. · 3.23 Impact Factor

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