For the first time New Zealand climate change scientists have captured the tiny organisms living on deep marine reefs that feed many of our fish species.
They’re a critical part of the food chain, but until now no one has researched these deep reef micro invertebrates living 65 metres below the surface. So the researchers built a homemade 'light trap' to catch the critters.
Victoria University Fish Expert, Alice Rogers, wants to find out if the fish from the shallows go to deeper reef environments to feed on the microscopic critters living on mesophotic reefs, reefs that are deeper than 20 metres.
"It’s all about finding out how fish food varies over depth," Rogers told Newshub.
To do that she’s on a research project in the Poor Knights Islands Marine Reserve in Northland, using a specially designed ‘light trap’. The trap is made from a round PVC pipe and has a green LED light which draws the microscopic organisms into it.
"It’ll attract all the little micro vertebrates that are locally on the reef, they’ll swim in through the entrance then they’ll be trapped inside," Rogers said.
The traps are placed at 10 and 50 metres of depth on the reef. The deeper ones are taken down using a remotely operated vehicle, known as an ‘ROV’.
It can drop off and pick up equipment as deep as 200 metres, and this is the first time they’re using it.
"Our idea is that these deep reefs might be really important for supporting fish communities and coastal fish. And that the fish that live here really rely on this food source.. And go down there to eat lots of these little beasties that potentially wouldn’t be there if there was only shallow habitat," Rogers said.
The traps are left in the water overnight and when they’re brought back on board and opened up, they’re teeming with tiny critters. Those are sieved out and stored in plastic tubes, ready to be transported back to the lab in Wellington.
The light traps are built by Alice’s partner Norbert Englebert on their kitchen table.
"It needed a little bit of a different design these light traps. Because you need to sample close to the reef.
"That’s why I came up with a tube with directional light. So you can position the light traps towards the reef," Englebert told Newshub.
And they’re a big success, capturing 12 samples from the two day voyage.
To collect samples from the marine reserve, the scientists secured a permit from the Department of Conservation and consulted with local iwi, Ngatiwai.
Ngatiwai’s Roxanne Pene is onboard watching the researchers work in an area which is of great value to the iwi.
"It’s really important because of its taonga species and its flora and fauna. And it’s cultural significance to hapu and iwi." Pene said.
A rich ecosystem that marine biologists hope their research will help protect.
