Where have all the aquatic plants gone?

Residents and water sports enthusiast may have been enjoying the open waterways of the Century City canals over the last couple of months, but there is something else lurking behind this seemingly “good look” to our canals. The aquatic plants* (or algae** as they are sometimes referred to), play a crucial ecological role in maintaining a healthy ecosystem at Century City, both to the canals as well as the Intaka wetland & bird sanctuary. The most common aquatic plants found in Century City include duckweed & pond lilies (floating), hornwort & pondweed (submerged); and common cattail & bulrushes (emergent).

Aquatic plants, algae and blue green algae are a natural part of an aquatic ecosystem and are present in healthy water bodies. They are essential to life in a wetland or river, acting as shelter, a food source and providing the oxygen necessary for fish and other aquatic organisms to survive. Aquatic plants rooted in the sediment also help prevent erosion and protect shoreline. Complex habitats that support diverse predator and prey species are less likely to be dominated by nuisance species – such as midges. Aquatic plants play an integral role in the uptake and storage of excess nutrients from our wetlands and canals. Algal growth is a threat to the system, but dominance by more complex macrophyte aquatic plants helps to keep floating algae at bay. In systems such as Century City, aquatic plants require management so that the water bodies continue to look pleasing and function optimally.

Over the last couple of months, we have seen a major decrease in the aquatic plant populations in the canals. Winter and Spring especially is the time when these plants seed, which is why it is important that we protect the new growth during this time if we are to ensure the population recovers successfully.

Our Environmental team engages on an ongoing basis with various Freshwater Specialists, Ichthyologist as well as the Blouvlei Intaka Environmental Committee, to ensure we manage the ecosystem in a sustainable and responsible manner. They have recommended that all harvesting in the canals be put on hold until such time as the aquatic plants have restored significantly.

We thank all residents and water users for their ongoing support, patience and consideration and will keep you informed of progress.