Commonly called rock snot but more properly known as didymo, the algae builds up on river rocks and is toxic to native fish. Logan Williams tells the New Zealand Herald he began looking at ways to repurpose the “disgusting brown sludge” because he is an avid fisherman and was disturbed by how its proliferation negatively impacted fish populations.
“Once it’s established it just takes over everything and the river effectively dies,” he says. “It was affecting river after river from the Rangitata to the Tekapo and devastating native populations in the process. Unfortunately for us this stuff thrives in cold, clean and low nitrogen water, so the South Island’s climate is perfect.”
He went on to found Biome Innovation to commercialize the process.