Awesome! There’s algae in my water!

Algae in your water is generally unwelcome. Except if it’s a rare hardly-ever-seen algae and the water is a pristine natural wetland.

That’s the good news from Cape Town, where the city this week reported the first confirmed record of a healthy-looking bloom of water net algae. The globular-shaped algae, which used to be prevalent a century ago but has largely disappeared from wetland areas, is considered a sign of good ecosystem health. It has been spotted in recent years but never formally recorded in an official database until now.

This is a very special find and highlights the importance to conserve these sensitive ecosystems to the best of our abilities.

—  Eddie Andrews, Cape Town mayoral committee member

The find is all the more remarkable because the algae was found inside the Milnerton Racecourse Conservation Area, not far from the Milnerton Lagoon where hazardous pollution levels are not uncommon due to raw sewage spills.

“It is the first confirmed record of this species on the iNaturalist database, which is exciting for the reserve and the City of Cape Town,” said Eddie Andrews, the city’s mayoral committee member for spatial planning and environment. “This is a very special find and highlights the importance to conserve these sensitive ecosystems to the best of our abilities.”

He said staff of the Table Bay Nature Reserve who manage the Milnerton Racecourse Conservation Area had been actively looking for the species since September last year when it was last spotted. The algae survives dry periods in the soil as spores and re-emerges in winter. “On 26 July 2022, it was found during a routine patrol of the Milnerton Racecourse Conservation Area. It was found in a very small seasonal pond in the conservation area,” Andrews said. “It’s a Cape floristic region endemic and an extremely rare find in this day and age due to urban development and habitat destruction,” he added.

Jenny Day, emeritus professor of freshwater ecology at the University of Cape Town, said: “I’m not a botanist but I am interested in Cape Town’s wetlands and was delighted to hear about and later see Hydrodictyon [it’s scientific name is Greek for ‘water net’]. It is a very rare occurrence – I’ve only heard of it showing up in Cape Town wetlands three or four times in the last 50 years. It lives only in temporary wetlands and seems to be quite sensitive, so its presence suggests that the wetland is in very good condition. It’s a pity that we don’t have more defunct racecourses – the area within the racetrack is beautifully protected and forms a rare island in suburbia – Kenilworth is the same.”

Pictures of the find posted on social media this week prompted lively commentary. “Who’d have thought algae could be so sexy,” said one commentator. “This is why it is so important to do beach, river and estuary clean-ups — nature heals itself if we give it a chance,” said another post.