Algae bloom in Point Waterfront Canal

THIS Summer has been a blazing one for Durban residents, leaving many hot, bothered and sweat soaked.

For the algae that grows on the surface floor of the Point Waterfront Canal, and for the small marine creatures that feed on the algae, this summer has been a plentiful one.

The recent hot weather has sparked a reaction in the small ecosystem that exists and thrives in Durban’s Waterfront Canal.

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The Point Waterfront Canal is a popular attraction in Durban, where strollers can amble along the canal, or take a boat ride on the popular Gondolas.

Of late however, canal visitors have been complaining that the water is murky, with bits of, what looks like moss, floating on the water’s surface and according to Simon Chater, the curator of the uShaka Marine World Aquarium, “People have begun to compare the canal to a swamp.”

Chater said the ‘floating green moss’ is in fact bits of algae and it is a sign that the algae that grows on the floor of the canal is blooming rapidly.

“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 of time in the canal on several occasions every summer,” said Chater.

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According to the curator, this also means that the various species of fish that live in the canal are prospering.

“There are currently over 50 species of fish in the canal, the most colourful of which are the wrasse and butterflyfish. Herbivorous species such as surgeon fish and mullet eat the algae that naturally grows on the walls and bottom of the canal,” he said.

This efficient ecosystem was introduced to the canal more than 18 years ago when uShaka Marine World was initially built.

“In 2003, soon after the canal was filled, the uSkaka Marine 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,” said Simon.

The caretakers of the canal want the public to know that the algae bloom is not a sign that the water is dirty, according to Chater, it’s a perfectly normal phenomenon.

“Algae is a big part of the ecosystem and the colour of the water and the appearance of the algae on the water’s surface is a sign that the system is healthy,” said Chater.

Another misconception is that the water is still and not free-flowing.

“The Point Waterfront Canal is fed from the outflow of seawater from the uShaka Marine World aquarium and that means that the canal water is never stagnant,” said the aquarist.

The water appears to be green and murky, but Chater said that there is an explanation for that too.

“There are small organisms that live in the water called phytoplankton and they give the water that green colour. Phytoplankton use chlorophyll to produce carbon by photosynthesis. Due to the green pigment of the chlorophyll, the organisms reflect green light,” explained Chater.

The algae bloom at the canal is not permanent, according to Chater the algae should clear up soon.

“I admit it doesn’t look pretty now, but the water should be clear within a week or two, you will be able to see the many forms of life that live in the water again soon. Once the system compensates for the rise in heat, it will go back to normal,” he said.

Something else to look forward to is that there are two exciting new residents swishing their tails in the canal, the canal managers have placed two hammerhead sharks into the canal, which Chater said will be visible once the water clears up.

Contact the Durban Waterfront Management Association (DPWMA) on 031 332 1099 for more information on the Durban Point Canal.