Exotic Caulerpa surveillance – The Noises islands – Aug 2023

In the picturesque last days of winter around The Noises, Revive Our Gulf and Coast & Catchment, conducted video surveys around the Island group. Our goal? To check for the presence of two invasive Caulerpa species: Caulerpa brachypus and Caulerpa parvifolia

The marine habitats surrounding The Noises are diverse – including rocky reefs, kelp forests, large sponges, shellfish, and rhodolith beds. Some of these high-value habitats would be particularly sensitive to the potential impacts of exotic Caulerpa.

The survey locations were carefully selected in consultation with representatives Ngāi Tai ki Tāmaki, The Noises Trust, and Auckland Council’s marine biosecurity team.

The primary method of exploration involved utilising a towed camera to capture video transects along the seabed. The footage was then meticulously analysed to detect any signs of Caulerpa. Thankfully, no Caulerpa was spotted in any of the 20 transects, covering a total of 4.9 kilometers of seabed.

While the survey was extensive, no method is without limitations. It’s possible that small or early-stage Caulerpa growth, low-density patches, or Caulerpa concealed by other features, such as kelp, may have been missed.

In total, the 20 transects covered an area of 6,000 square meters, which represents just 0.01% of the proposed 60-square-kilometre High Protection Area proposed for The Noises. This underscores the enormity of the surveillance efforts needed to ensure the safety of these coastal ecosystems.

Photos by Peter Miles

Visit the Exotic Caulerpa Response project page