Plastic islands being used to restore African lake
By Ben Coxworth
September 21, 2012
As the ever-growing giant flotilla of floating refuse known as the Great Pacific Garbage Patch will show us, we shouldn't be putting plastic waste in our waterways. A new project, however, is aimed at helping the environment by doing so ... in a roundabout way of speaking. The participants plan on taking several artificial floating islands made from post-consumer plastic, planting papyrus on them, and then using them to help rebuild the ecosystem of Africa’s Lake Naivasha.
Located in Kenya’s Rift Valley, the lake was crystal clear 30 years ago. Since then, a 20-fold increase in the local human population, along with foraging activity by water buffalo native to the region, has resulted in massive clearing of the lakeshore papyrus plants.
Like other aquatic plants, papyrus serve a vital role. Acting as biofilters, they trap suspended sediments, plus they remove toxic substances and excess nutrients from the water. Unfortunately, the destruction of much of the lake’s papyrus plants has led to a marked decline in its water quality.
The restoration project is being funded by the German REWE Group. It involves the participation of UK tea producer and flower grower Finlays (which grows flowers in the region), and is being led by Dr. David Harper, a senior lecturer at the University of Leicester.
The team plan on introducing a new population of papyrus to the lake, at a spot where silty water from the Malewa River enters into it. Those papyrus will be planted on a series of BioHaven Floating Islands, made from recycled polyester drink bottles by North Carolina-based Floating Island Southeast.
Each BioHaven island is essentially a floating mat, made up of multiple layers of a plastic matrix bonded together with marine-grade foam. This provides a highly buoyant surface for plants to grow on, while allowing their roots (which dangle beneath the island) to both act as a sediment filter, and as a home for aquatic microbes. Those microbes feed on nutrients that might otherwise lead to excess algae growth – a service also provided by the plants themselves.
Additionally, the roots should serve as feeding grounds and nurseries for fish, while the five meter (16 foot)-tall stalks of the plants should make a good habitat for birds.
The islands have been ordered, and will be anchored in place once the papyrus is planted on them. If they prove successful at their first location, additional islands will be installed at other locations along the lake shore.