Benthic cyanobacteria attaches to river beds, and can detach and float freely. Its appearance depends on species - Phormidium looks like a thick and velvety black or brown mat and has a musty, earthy smell, while Nostoc forms small globular mats.
Routine monitoring for potentially toxic benthic cyanobacteria is carried out at a number of river sites that are popular for recreation throughout Canterbury.
Popular rivers and streams used for recreation are currently being monitored around Canterbury for blooms of potentially toxic benthic cyanobacteria.
Popular bathing sites with moderate-high cyanobacteria cover now have warnings in place. However, sites with low cover of cyanobacteria can rapidly increase at anytime and river users should keep vigilant. For what to keep an eye out for and more information visit Cyanobacteria warnings or read our brochure.