Didymo Screening

The GNS Science geomicrobiology team has carried out screening of New Zealand river samples for the invasive Didymosphenia geminata (didymo), also known as "rock snot", in late 2007.


Didymo is a freshwater diatom (a type of alga) that can be spread by a single drop of water. Didymo sometimes forms massive blooms on the bottom of the streams, rivers and lakes. It attaches itself to the stream bed by stalks, and can form a thick brown layer that smothers rocks, submerged plants and other materials.

Our scientific analysis, in support of Genesis Energy, MAF and other analytical laboratories, confirmed that didymo waste was not present in North Island rivers.

For more information visit the Ministry of Agriculture and Fisheries.