Toxic algae in Wellington harbour


The toxic algal species that has caused the current outbreak on the west coast of the North Island has finally been detected in Wellington Harbour.

The algal species that triggered the latest toxic shellfish outbreaks along the North Island west coast has been detected in Wellington Harbour by a scientist at the National Institute of Water and Atmospheric Research (NIWA).

Low cell concentrations (less than 100 cells per litre) of this microscopic, single-celled, chain-forming, toxic algal species were detected for the first time on 10 September. The species responsible, Gymnodinium catenatum, was found in water samples collected both inside Wellington Harbour and in several areas stretching from Breaker Bay to Red Rocks on the southern coastline. To the west, along Makara Beach and Titahi Bay in Porirua Harbour, much higher cell concentrations were recorded (ranging from 1000 to more than 3000 cells per litre).

Last weekend’s stormy weather did not appear to hinder the build-up of this algal species on the open coast. The cell concentrations recorded at both Makara and Titahi Bay last weekend were many times greater than the concentrations recorded in the previous week.

Two weeks ago, surface water samples were collected by scientists on a NIWA research vessel along a line stretching from Farewell Spit through Cook Strait to Wellington Harbour. At that time, Gymnodinium catenatum was not detected in any of the water samples.



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Archived on 9 April 2019