Vegetation invasion influences waterbird assemblages and aquatic environmental parameters in urban areas of Dar es Salaam, Tanzania

Abstract

Waste Stabilisation Ponds (WSPs) serve as refuge habitats for waterbirds in response to the decline of natural wetlands especially in urban settings. Various sewage treatment stages within WSPs attract waterbirds differently based on the specific characteristics of each stage. This study examines the influence of treatment stages on both vegetated and non-vegetated WSPs over a period of one year in Dar es Salaam, Tanzania. Bird surveys were periodically conducted at each treatment stage along with different environmental variables; dissolved oxygen, electrical conductivity, water turbidity, water temperature, pH, and invertebrate biomass. In non-vegetated WSPs, waterbird densities and invertebrate biomass were significantly higher in facultative ponds than in maturation ponds (p < 0.05). The water pH was higher in maturation ponds than in facultative ponds (p < 0.05). However, in vegetated WSPs, no notable variations in waterbird density and environmental variables were observed across different treatment stages (p > 0 .05). The presence of vegetation in WSPs created similar environmental conditions across treatment stages, potentially reducing waterbird preferences for specific stages. These findings underscore the importance of understanding the characteristics of sewage treatment stages in order to enhance the management of WSPs as suitable habitats for waterbird populations in urban areas.