Today was damned hot in Adelaide: the maximum reached 39 degrees Celcius.

My decision to go for a run along the River Torrens was not a good one, given that (a) the sun was already fierce and temperature high, although only 8am and (b) the water-way was a stinking, stagnant mess.

This shot shows blue-green algae just near the Adelaide Zoo-section of the river.

Blue-green algae is a misnomer: the growing mass is actually comprised of a type of bacteria called cyanobacteria. Although a natural part of the freshwater environment, according to the Murray-Darling Basin Authority,

“If conditions are favourable, they reproduce at very high rates to form ‘blooms’ – explosions in growth that dominate the aquatic environment, forming unpleasant and sometimes toxic scums.”

Blooms arise when non-flowing pools of water collect in sunny, protected areas: this in turn allows a layer of warm, sun-drenched water to sit at the surface and create perfect conditions for the cyanobacteria colonies to multiply. Like plants, the bacteria generate their own source of energy by photosynthesis.

Water containing blue-green blooms is not fit for swimming or consumption due to the toxins produced by the bacteria. Amazingly, today I saw two little water birds paddling about in the scum shown in the image. I hope their health is still good.

Blooms in the River Torrens have been triggered by recent hot weather combined with low rainfall in South Australia: what we need now is a little rain and a drop in temperature to clear it up.

Tommorow’s forecast is minimum 27 degrees, maximum 39 again.