Macrophyte species composition and abundance of hydrogeologically connected wetlands in upper Abbay river basin, Ethiopia

Abstract

Macrophytes are key components of aquatic ecosystems including wetlands that have considerable ecological importance. The role of macrophytes is closely linked to their structural attributes like species composition and abundance. Therefore, this study aimed to assess macrophyte species composition, abundance and diversity of six hydrogeologically connected wetlands in the upper Abbay River basin, Ethiopia. The studied wetlands (Gudera, Geray, Zindib, Kurt Bahir, Infranz and Wonjeta) are found in west Gojjam administrative zone, Amhara region, Ethiopia. Two cross-sectional surveys were conducted at the end of September 2021 and February 2022. Quadrat sampling technique was employed to collect macrophyte samples following protocols for sampling aquatic macrophytes in freshwater wetlands. A total of 41 species of macrophytes belonging to 16 families were identified across the wetlands. The wetlands were dominated by emergent macrophytes, with the Poaceae and Cyperaceae families being particularly abundant. The physicochemical water quality status, water level fluctuations and level of human interventions might be the reason for the variation in the macrophytes composition, abundance and diversity across the wetlands. The low macrophyte diversity index value and the presence of pollution-tolerant taxa such as Pistia stratiotes and Azolla africana indicate an overall ecological degradation of the wetlands. Therefore, this study highlights the potential role of macrophyte monitoring to identify anthropogenic pollution. Application of appropriate land use planning and the development of macrophyte based multimetric indices are recommended for their sustainable management.