Summary

This document presents interim guidelines for the monitoring and risk management of marine benthic cyanobacteria in Aotearoa New Zealand. Marine benthic cyanobacteria, particularly mat-forming species such as Okeania spp., have been increasingly observed in temperate coastal regions, with recent blooms affecting public health, local ecosystems, and recreational water use. These organisms can produce cyanotoxins—such as lyngbyatoxins and aplysiatoxins—which are known to cause dermatitis, respiratory irritation, and other adverse health outcomes through dermal contact, ingestion or inhalation. These interim guidelines consolidate national and international science, historical monitoring data, and recent bloom events across Auckland and other regions, and propose a four-stage response framework.