An underwater surveillance project to better understand where exotic caulerpa is (and isn’t) has wrapped up. The project was jointly funded by Auckland Council, Aotea / Great Barrier Local Board, the Aotea Environmental Trust and Biosecurity New Zealand.
Eight trips surveying for exotic caulerpa were carried out from November 2023 to June 2024 using a camera on a remotely operated vehicle, targeting different areas and covering nearly 70,000 square metres.
During these trips, there were 692 site dives with the remotely operated vehicle, and exotic caulerpa was detected 150 times throughout the project.
“This information is a huge help when we’re looking at options in regard to exotic caulerpa response for the motu,” says Aotea / Great Barrier Local Board chair, Izzy Fordham.
Using a remotely operated vehicle for the survey had many advantages, including its ability to go beyond recreational dive limits and high currents. It was able to dive deeper than 40 metres, sometimes to a depth of nearly 50 metres.
The vehicle was also able to inspect spots which would typically be hidden from view such as under ledges and dense kelp. This was helpful because the survey results noted that in shallow water, exotic caulerpa was more often found in areas without direct sunlight.
The contractor for the survey, Logan Marine Projects, concluded that the survey was successful in determining the areas with exotic caulerpa presence along the coastline of Aotea.
The report acknowledges: “Aotea underwater is a special place, and needs to be protected, but this comes from first understanding what is truly down there. We have worked hard to contribute and help, and the data obtained can now be used for generations to come, to understand the shifts and patterns of our underwater taonga - our natural treasures.”
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