Macroinvertebrate assemblages along a gradient of physicochemical characteristics in four riverine wetlands, Upper Blue Nile basin, Northwestern Ethiopia.

This study aims to examine the physicochemical variables that influence macroinvertebrate assemblages in wetlands of the Fetam River watershed. Macroinvertebrates and water quality samples were collected from 20 sampling stations across four wetlands between February and May 2022. Principal component analysis (PCA) was used to elucidate the physicochemical gradients among datasets and canonical correspondence analysis (CCA) was applied to explore the relationship between taxon assemblages and physicochemical variables. Aquatic insects such as Dytiscidae (Coleoptera), Chironomidae (Diptera), and Coenagrionidae (Odonata) were the most abundant families, and they comprised 20-80% of the macroinvertebrate communities. As demonstrated by cluster analysis, three site groups including slightly disturbed (SD), moderately disturbed (MD), and heavily disturbed (HD) sites were identified. PCA showed a clear separation of slightly disturbed sites from moderately and highly impacted sites. Differences in physicochemical variables, taxon richness and abundance, and Margalef diversity indices were observed along the SD to HD gradient. Phosphate concentration was an important predictor that influenced richness and diversity. The extracted two CCA axes of physicochemical variables accounted for 44% of the variability in macroinvertebrate assemblages. Nutrient concentration (nitrate, phosphate, and total phosphorus), conductivity, and turbidity were the main drivers of this variation. This suggested the need for sustainable wetland management intervention at the watershed level, ultimately benefiting invertebrate biodiversity.

The driving forces of wetland degradation in Bure and Wonberma Woredas, Upper Blue Nile basin, Ethiopia.

Although the land use/land cover (LULC) of inland wetlands has been dynamic over the last 100 years, the extent of their LULC dynamics and its driving forces are poorly understood particularly in Ethiopia. Thus, this study analyzed spatiotemporal dynamics of four (Alefa, Chakun, Denbun, Kotilan) wetlands LULC and its driving forces in the Bure and Wonmbera Woredas, Upper Blue Nile Basin, Ethiopia for the period from 1985 to 2020. The Landsat images downloaded from Google Earth Engine were used to analyze the LULC of four wetland watersheds. These images were classified into 7 classes by using the maximum likelihood algorithm in ArcGIS 4. Besides, a survey of 347 households, 4 focus group discussions, and 12 key informant interviews and transect walks were used to generate the data on the drivers of wetland changes. The LULC analysis showed that the four wetlands area in 1985, 2002, and 2020 occupied 6027 ha, 5203 ha, and 4348 ha, respectively, which indicated that the areas of wetlands have declined by 1679 ha or 27.9% in the past 35 years, with an average annual decrease rate of 48.4 hectares. Wetlands were lost at a higher rate (16.4%) from 2002 to 2020. The cultivated land expansion has taken a substantial share (67.9%) of wetlands' decline. The expansion of cultivated land due to an increase of rural households along with a lack of alternative livelihoods resulted in the conversion of wetlands to cultivated land. Gully erosion and sediment deposits due to wetlands buffer degradation, overgrazing, and change in crop production driven by market opportunities have exacerbated the wetlands loss. Thus, interventions such as the promotion of alternative livelihood activities, stall livestock feeding or zero-grazing, and non-conventional livestock feeds are needed to curb wetland degradation. Delineation of buffer zone and protection of shrubland or woodlands found in buffer areas of the wetlands are needed as well for the sustainability of wetlands.

The Potential of Wetlands as Treatment Systems for Organic Matter and Some Selected Metals (As, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Pb, and Zn): Case Study of Yitamot Wetland, Ethiopia.

Organic matter and some selected metals (As, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Pb, and Zn) were measured from water and sediment while plant samples from the inlet to the outlet sampling sites using standard procedures from three compartments (water, sediment, and macrophytes) of Yitamot wetland. Findings indicated that the mean concentration of COD in water was in the range of 5.25 mg/L and 208.25 mg/L and showed a significant and exponential decrease along the subsequent sampling sites (P < 0.05). The mean concentrations of K, As, Cd, and Cr (82.192 mg/kg, 0.730 mg/kg, 0.06 mg/kg, and 19.776 mg/kg, respectively) were significantly lower values in the outlet than in the inlet of the sediment samples (P < 0.05). All the metal concentrations in the aboveground tissue of macrophytes were significantly lower at the outlet sample site (P < 0.05) indicating that these compartments are contributing to the retention of metals and organic matter present in wastewater discharged in the wetland through sinks and conversions of these compounds. However, there was no significant removal effect for heavy metals like Fe, Zn, and As (P > 0.05). This is a pointer to the fact that natural wetlands can be used effectively for wastewater treatment with strong monitoring programs and ecological indicators for the sustainable management and conservation of the flora and fauna present in it.