Blue-Green

Sunday's Ironman event in Remich was supposed to begin with a swim in the Moselle. It did not. Organisers cancelled the swimming leg shortly before the scheduled start after blue-green algae were detected in the river. The race was reduced to cycling and running, with the start pushed back to 8:25pm.[1]

Blue-green algae, or cyanobacteria, thrive in warm water. They can produce toxins harmful to people and animals. By Thursday, the Moselle had already warmed to more than 26°C, which meant neoprene wetsuits would not have been permitted for the swimming leg anyway. The algae were the final blow.[1]

The heatwave cascade

This is the same heatwave that has now lasted four days under a yellow alert. The same heat that pushed classrooms to 35°C and triggered water restrictions across the country. Hot air heats the river. Warm water grows algae. Algae cancels the swim. The chain is direct and unsurprising.[1]

For the athletes who trained for months, the cancellation is a disappointment. For the Moselle, it is a symptom. Rivers are ecosystems, and ecosystems respond to sustained heat faster than buildings do. A classroom at 35°C is uncomfortable. A river at 26°C grows algae that can kill a dog that drinks from it. The heatwave is not just a matter of human comfort. It is cascading through the natural environment, and the effects will outlast the alert.[1]

Ironman without the water

An Ironman without a swim is not an Ironman. It is a very long bike ride followed by a marathon. The organisers made the right call: safety trumps format. But the image of hundreds of athletes lining up in Remich to cycle and run, skipping the river that was too warm and too toxic to enter, is the image of this summer. The heatwave does not cancel events. It transforms them.[1]