Image Source: https://www.abc.net.au/
Researchers have found a new reef that is as tall as a skyscraper in the waters off Cape York in North Queensland.
The ‘detached’ reef — the first to be discovered in more than 120 years — is about 1.5 kilometres long, and rises from over 500 metres deep up to 40 metres below the surface.
Researchers discovered the reef, which is estimated to be 20 million years old at its deepest part, on October 20 during a 12-month mapping project of Australia’s oceans.
A “detached” reef refers to a reef bedded to the ocean floor and not part of the main body of the Great Barrier Reef.
The newly-found reef sits among a cluster of seven other detached reefs that were mapped in the 1800s, however the marine ecosystem on the top of this latest find appeared to be more vibrant than the others, according to research leader Robin Beaman from James Cook University (JCU)
“It’s got a thriving coral community at the pinnacle,” Dr Beaman said.
“When we got to the crest of it — it’s only about 300 by 50 metres wide — we found a lot of fish and a healthy shark population too.”
Detached reefs of this nature act as isolated seamounts, according to Dr Beaman. Because there is a lot of deep water between it and the next coral community, they have the potential to evolve unique species.
The team has been exploring the reef using an underwater robot called “SuBastian”, which has a remotely controlled arm, to collect samples for identification.
“As a collective over the entire [12-month] expedition, we’ve been finding a whole lot of new species,” Dr Beaman said.
“It’s going to take time for us to work through the imagery and samples we’ve collected before we can say if there are new species [at this reef] or not.”
They made the discovery about 80 kilometres east of Cape Grenville, which is about 150 kilometres south of the tip of Cape York on Queensland’s east coast.
The researchers found new reef building evident within the photic zone, which extends down to around 200 metres.
The photic zone — where enough sunlight penetrates to provide direct energy via photosynthesis — would have moved up and down the reef over time as sea levels fluctuated.
During the last ice age when oceans were around 120 metres lower than today, some of the reef would have been in much shallower water, or even exposed.
‘World’s longest recorded sea creature’ among new finds
The scientists are working onboard the research vessel “Falkor” which is being funded by the Schmidt Ocean Institute — a research body founded by American philanthropist and businesswoman Wendy Schmidt, and her husband, former Google CEO Eric Schmidt.
Several new species have already been discovered during the project, as well as the “world’s longest recorded sea creature” — a 45-metre long siphonophore at Ningaloo canyon off Western Australia, according to Schmidt Ocean Institute spokesperson Carlie Wiener.
A siphonophore is a colonial organism comprised of zooids — multicellular animals that are functionally specialised to allow the colony to digest food, float, reproduce and move through the water.
She said their latest reef discovery demonstrated the value of the project.
“Australia has no dedicated underwater vehicle, so there are a lot of areas that haven’t been looked at before,” Dr Weiner said.
“This is evidence for the importance of exploring our undersea environment, so that we can protect it.”
Tuesday’s announcement comes just a fortnight after the publication of findings that since 1995 half the corals on the Great Barrier Reef have died due to climate change induced coral bleaching.
Co-author of that study, reef scientist Terry Hughes from James Cook University said the extent of deeper reefs like this one — known as mesophotic reefs — is only now becoming known as technology has improved.
“Mesophotic reefs — reefs deeper than 30 metres — it turns out there’s probably at least as much coral habitat below 30 metres as there is above it, and people are still mapping it,” Professor Hughes said.
Because of their depth and distance from shore, mesophotic reefs are less susceptible to bleaching, cyclones, fishing pressure and land-based pollution, however they are still degrading, albeit at a slower rate than their shallow-water counterparts.
But because of what is known as “zoning”, mesophotic reefs aren’t going to help restock shallower reefs damaged by bleaching events or other impacts, he said.
Zoning refers to the limited depth range that most coral and other marine species are restricted to.
“There’s been some speculation that’s pretty well resolved now, that the deep reefs could be reserves for the shallow ones. That turns out not to be the case,” he said.
“Many corals are shallow water specialists and others are deep water specialists and only a few have a broader depth range. There are corals that you only find shallower than five metres [and] there are other corals you only find deeper than 30.”
While findings like this are interesting, Professor Hughes said that we still need to urgently get emissions down to protect shallower corals.
“We still have an opportunity to save the reef if we deal with climate change. 1.1 degrees of warming so far has triggered five bleaching events since 1998 [but] we still have half a reef.”
“What [warming] stabilises at will be critical. 1.5 to 2 C is doable, but the mix of species will be different. It already is.
“If we go to 3 or 4C it will be a pretty sad state of affairs.”