Researchers exploring the deep waters off the Fiordland coast have caught on camera marine communities that have never been filmed before. These communities include a protected species of red coral that has not previously been seen in such large numbers.

“We were filming at depths of 80 to 130 metres and found amazing marine communities. The most incredible find—unlike anything we have seen elsewhere—was about 4 kilometres north of the entrance to Doubtful Sound/Patea. On the ocean floor, we saw forests of bright red coral,” said Professor James Bell, a marine biologist at Te Herenga Waka—Victoria University of Wellington.

The coral species, Errina novaezelandiae, is commonly known as red coral, although it is not a true coral but a related animal called a hydrocoral.

The discovery of the red coral forests was made while the researchers were working on a project to explore and map marine life in Fiordland’s deep waters. They were working on board the Department of Conservation (DOC) vesselSouthern Winds.

“We’ve been exploring these deep reefs in Fiordland for many years, but we’re rarely able to work on the open coast outside the fiords because of the weather. On our most recent trip in January, the weather was finally on our side,” said Professor Bell.

Using a remotely operated vehicle (ROV), the research team collected video footage of reefs at depths of greater than 100 metres in areas that have not previously been filmed.

“We’ve deployed the ROV more than 100 times in deep waters around New Zealand, but we have not seen communities like those we found off the open coast outside Doubtful Sound/Patea. In other parts of the country, we usually find reefs at these depths are dominated by sponges. In this area off the Fiordland coast, red corals dominated. The water was also incredibly clear down at 100 m and we could see the reef from a distance of about 30 to 40 m,” he said.

Red corals are known to live in some places inside the fiords and are considered to be associated with the sheltered fiord conditions. The population discovered around the open coast was distinguished by its massive size, with tens of thousands of corals seen.

Video footage of the reefs shows numerous red corals, along with a range of other animals including larger black corals. Both red and black corals are protected species under the Wildlife Act.

These coral forests play a key role in maintaining habitat diversity, supporting many fish and crayfish species, said Professor Bell.

“Filming the animals that live on these deep-water reefs provides us with more information about the extraordinary biodiversity in our seas. This information is crucial to decisions about the use and protection of our marine environment. While much of Fiordland’s inland waters are protected, this is not the case for the open coast. In fact, most deep-water reefs around Aotearoa are not protected in marine reserves,” he said.

The research was supported by the George Mason Charitable Trust and DOC’s conservation services programme. DOC also provided logistical support.

Richard Kinsey, a DOC senior ranger who was on the trip, said: “It is exciting when you get to put the ROV into places you can rarely access as it gives insights into a completely different part of the fiord ecosystem. You just never know what you are going to find. For DOC, increasing our understanding of where these protected species are helps us to understand the potential threats to them.”

DOC senior science advisor Lyndsey Holland added: “Our understanding of protected coral distribution in Fiordland is dominated by black corals. Other protected corals in the area haven’t been studied as extensively, so this finding is a breakthrough. We do know that New Zealand boasts a diverse array of cold-water corals offshore, so this discovery validates the need to survey and monitor Fiordland corals so we can best protect them.”

Video footage of the deep-water reefs off Fiordland is here:

https://www.youtube.com/watch?v=6mxS4RaYXiI