By Ann Kunz
Algae bloom in the Point Waterfront Canal
The Point Waterfront Canal is fed from the outflow of seawater from the uShaka Sea World aquarium. In 2003, soon after the canal was filled, the uShaka Sea World staff introduced several species of fish into the canal. These fish were primarily herbivores and they grazed happily on the abundant algal growth in the canal.
There are currently over 50 species of fish in the canal, the most colourful of which are the wrasse and butterflyfish. Not all of them are herbivores and supplementary surplus food is fed to the fish by the uShaka Sea World aquarists. Herbivorous species such as surgeon fish and mullet eat the algae that naturally grows on the walls and bottom of the canal. We find different types of algae growing on the walls and bottom, and amongst the algae live animals such as shrimps, marine worms, molluscs and bivalves.
These plants and animals play an important role in ensuring that the marine environment and water quality of the canal remains healthy.
During the hot summer months, the rise in temperature causes some species of algae to `bloom’. Much like our lawns, which grow at a faster rate when there is a seasonal increase in rainfall, algae blooms occur when there is an increase in temperature and sunshine. This situation occurs over short periods in the canal on several occasions every summer.
Although the aquarists monitor the algae on a daily basis, this algae bloom is a natural phenomenon and poses no harm to the animals.