Didymo has been detected in a number of freshwaters in the South Island. It has not been detected in the North Island, but that is no guarantee that rivers there are unaffected - didymo is microscopic, so the risk of spread will not always be obvious.
This map shows sampling sites and waterways where didymo has been found.
Didymo Samples Database
The didymo samples database is an internet based system that provides a single source registry to record all didymo sampling results taken throughout New Zealand. The database includes both negative and positive results, and sample locations that are displayed on a map.
Read only access is available using the username Didymo and password didymosamples1.
Please email firstname.lastname@example.org to enquire about obtaining a username and password for write access to the database.
Didymo was first identified in the Lower Waiau River, Southland in October 2004. It was found during a routine Meridian Energy survey of alga growth by NIWA and Southland Fish and Game staff.
MAFBNZ has conducted a number of didymo delimiting surveys. Each survey included selected sites throughout New Zealand being sampled for the presence of didymo. For more information please see the links below with the results and reports from previous surveys.
2006-07 Summer National Delimiting Surveys (3093 KB)
August 2006 Delimiting Survey (1598 KB)
May 2006 Delimiting Survey (1054 KB)
January 2006 Delimiting Survey (757 KB)
October 2005 Delimiting Survey (2077 KB)
Likely environments map of the South Island
Likely environments map of North Island