Didymo

Didymosphenia geminata

Didymo

Didymo

Legal Status: Unwanted Organism - MPI
Status in New Zealand: Investigating
Organism: Marine and freshwater plants

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.

Didymo affected waterways: click for larger image
Click image to enlarge

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 didymo@maf.govt.nz to enquire about obtaining a username and password for write access to the database.

Delimiting Surveys

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 Link to PDF document (3093 KB)
August 2006 Delimiting Survey Link to PDF document (1598 KB)
May 2006 Delimiting Survey Link to PDF document (1054 KB)
January 2006 Delimiting Survey Link to PDF document (757 KB)
October 2005 Delimiting Survey Link to PDF document (2077 KB)

Likely environments map of the South Island

Didymo South Island Likely Environments map

Detailed Map Link to PDF document (16171 KB) (note large file size)
Static Map

Likely environments map of North Island

Didymo North Island Likely Environments map

Detailed Map Link to PDF document (14444 KB) (note large file size)
Static Map