Underwater drone captures life on reefs 65 metres deep

For the first time, we can see what's living on the reef 65 metres deep in Northland’s Poor Knights Islands Marine Reserve.

It was all captured on an underwater drone as part of a climate change research project by the Victoria University of Wellington.

“We’re really interested in understanding the impacts of climate change, particularly the impacts of marine heatwaves which we’ve seen for consecutive years in New Zealand," Victoria University Marine Biologist Professor James Bell told Newshub.

The mesophotic reefs - reefs deeper than 20 metres - have never been filmed at this depth and quality. 

The quality of the drone captured the reef in all its beauty.
The quality of the drone captured the reef in all its beauty. Photo credit: Newshub

Professor James Bell said until now, the public has never seen what the reef looks like at depths of 50 to 70 metres.

"There are technical divers that dip down into these depths, but these are some of the first images we are sharing from our ROV," he said.

The Remotely Operated Vehicle (ROV) is like a large underwater drone, it has a grabby arm for deploying equipment and gathering samples, plus large propellors and a high-quality camera.

A long cable connects it to a monitor on board the boat where the scientists can drive it, and view the reef in real-time.

The ROV can operate down to 200 metres, reducing the risk and cost of sending humans to those depths.

“It means we can film for longer in the water as well”, Bell told Newshub.

It’s funded by the George Mason Charitable Trust and is a game-changer for studying the link between sponge gardens at 50 to 60 metres, and the fish that feed there and hide from predators. 

“One of the things we are super interested to know is if there is an overlap between things that live in deep and things living in shallows."

It's the first time the public has seen what the reef looks like at this depth.
It's the first time the public has seen what the reef looks like at this depth. Photo credit: Newshub

They believe the deeper reefs might be more stable and less susceptible to climate change than the shallower reefs.

To find out they’re analysing the kaleidoscope of colourful sponges,  which contain precious information about how marine organisms are responding to environmental changes.

They have discovered that sea sponges are suffering as water temperatures rise. 

“Species around poor knights and other parts of NZ have declined.. Tissue has degraded in response to those warming waters. We are increasingly finding out that they have lots of important roles. If we lose those sponges we potentially lose other important things in the ecosystem," Bell said.

The research trip is also a learning ground for PHD student Manon Broadribb, who’s moved here from the UK.

“I came to study marine biology, the marine life here is crazy - the transition from sub-tropical all the way to sub-antarctic in one country is something you don’t see anywhere else in the world” Victoria University PHD Student Manon Broadribb said.

The sponges are of particular interest.

“I’m looking at communities transitions between shallow and deeper mesophotic reefs around here,” Broadribb told Newshub.

There are some thrilling finds to be had, such as the Organ pipe sponge (Leucosolenia), which Bell had never seen at Poor Knights.

“We finally found one of those down at 65 metres. I was quite excited to see that for the first time," Bell said.

The entire group of islands is a marine and nature reserve and has been under full protection since 1998, so the best way to appreciate its beauty is to get in the water.

There's a turquoise treasure trove of marine life, with more than 125 species of fish living here.

“I consider the Poor Knights to be one of the top 10 dive spots anywhere in the world I’ve been,” Bell said.

This is why it’s so important to learn more about how climate change threatens its very existence.