A few of us ventured out to Aiselby Farm in Mguza to birdwatch around the dam, river and surrounding areas. We set out in the morning and started birding from Aiselby Farm primary school.
As we were approaching the school by car, we soon realised that Aiselby Farm is teaming with birds and we were in for a treat. We had our binoculars looking in every direction seeing Fire Finches and Plovers forage on burnt patches of the ground, rollers in their aerial displays, Falcons, Kites and Eagles just to mention a few. After a 3 hour walk, we had recorded in total, forty-six species. However, while we were looking for birds, we couldn’t ignore the sight of a particular plant, Water Hyacinth (Eichhornia crassipes), that is doing too well and has important implications for the bird life of uMguza’s feathered residents.
Water hyacinth is a deceptively beautiful aquatic plant with lavender-blue flowers that hide its destructive potential. It is native to South America, and has made its way to various parts of the world as an ornamental garden plant. Unfortunately, its presence is far from benign; as an alien species, it tends to become invasive wreaking havoc on freshwater ecosystems. Water Hyacinth grows very well in still nutrient rich waters (pollution/fertilizer/sewage runoff). All these conditions persist in the Mguza river, a dam that slows down water flow and pollution from city sewage waste and runoff.
The Mguza river is a very important river urban catchment straddling the north of the city of Bulawayo. Over the past decades, ageing infrastructure in the city has resulted in the pollution of the river by waste water effluent. Its main tributaries coming from the city, Mazayi and Matshamhlophe, are popular for the stench of pollution they bear as they cut across the city from the industrial areas. This has resulted in extensive eutrophication and changes in the river and dam’s chemistry. Unfortunately, these conditions are ideal for invasive alien plants like Water Hyacinth. Since the 1980s, members of the Matabeleland branch of BirdLife Zimbabwe have been conducting annual waterfowl counts in the winter and summer months as it is an important bird breeding hotspot for waterfowl and migrants. They have noted with concern, the severe decline in avian biodiversity, the rising pollution and the watercourses being choked by the alien plant. Efforts to control it through removal and getting the city council to fix the influx of pollutants have been to no avail.
Due to the climate crisis, many African countries are grappling with water scarcity issues. Coupled with lack of infrastructure, developing countries struggle to meet the water resource needs of their growing populations. An alien invasive species like Water Wyacinth can be hard hitting, forming dense floating mats that block sunlight, deplete oxygen, choke water courses and disrupt water flows. This affects not only the plant and animal biodiversity in and around the river channels, but also the food and water security of communities relying on the rivers for fish and water. The unchecked growth of this invasive species disrupts freshwater ecosystems, reduces water availability for drinking and agriculture, and hampers transportation and livelihoods. These economic impacts on community livelihoods ripple through to affect the urban, provincial and in turn, national economy.
As young people, we enjoyed our time around Mguza dam and longed for it to return to its former glory. We watched over the horrendous mats of the alien plant and hoped for a solution. Fortunately, biological controls such as the Water Hyacinth Planthopper (Megamelus scutellaris), a bug native to South America where the plant is from, have proven to be potentially effective at controlling this plant, compared to manual removal and spraying with pesticides. We hope one day soon we will also enjoy the recreational activities the river and dam once boasted of, like fishing and boating, but mostly, the bird and wildlife around it.