Please select your home edition
Edition
Marina Exchange 728x90 1

Coral bleaching on the Great Barrier Reef not limited to shallow depths

by coralcoe.org.au 7 Sep 2018 11:02 UTC
Researcher, Norbert Englebert, running bleaching survey transects, Great Barrier Reef. © Pim Bongaerts

A team of international marine scientists working with the ARC Centre of Excellence for Coral Reef Studies at The University of Queensland (Coral CoE) has found evidence to suggest the 2016 coral bleaching on the Great Barrier Reef also affected deep reefs.

Although deep reefs are often considered a refuge from thermal anomalies caused by global ocean warming, the new research highlights limitations to this role and argues that both shallow and deep reefs are under threat of mass bleaching events.

Published in the journal Nature Communications, the new study focuses on the 2016 mass bleaching event that caused the death of 30 per cent of shallow-water corals on the Great Barrier Reef.

The study, details how the impacts of this bleaching did lessen over depth, but were still substantial even on the deep reef.

Lead author Dr Pedro Frade from the Center of Marine Sciences, in Portugal, said the scientists were astounded to find bleached coral colonies all the way down to 40 metres.

"It was a shock to see that the impacts extended to these dimly-lit reefs, as we were hoping that their depth may have provided protection from this devastating event," he said.

The Great Barrier Reef is known to harbor extensive areas of deep coral reefs, however given their depth these reefs are notoriously difficult to study. Using remotely operated vehicles, the team deployed sensors down to 100 metres to characterise how temperature conditions at depth differ from those in the shallow reef.

UQ Global Change Institute Director and Coral CoE's Deputy Director, Professor Ove Hoegh-Guldberg said the study had emphasised the unfortunate vulnerability of the Great Barrier Reef.

"We already established that the refuge role of deep reefs is generally restricted by the limited overlap in species with the shallow reef," he said.

"However, this adds an extra limitation by demonstrating that the deep reefs themselves are also impacted by higher seawater temperatures."

Co-author and Coral CoE alumnus, Dr Pim Bongaerts from the California Academy of Sciences said that during the bleaching event, upwelling cold-water initially provided cooler conditions on the deep reef.

"However, when this upwelling stopped towards the end of summer, temperatures rose to record-high levels even at depth," he said.

A team of divers then conducted surveys during the height of bleaching, across several sites on the northern Great Barrier Reef.

They noted that overall, major bleaching and mortality affected almost a quarter of corals at 40 metres, while confirming previous reports of nearly half the corals being severely affected at the shallower depths.

The researchers have now gone on to study how the process of recovery varies between shallow and deep reefs.

Related Articles

Sharks almost gone from many reefs
Finding of a massive global study of the world's reefs A massive global study of the world's reefs has found sharks are 'functionally extinct' on nearly one in five of the reefs surveyed. Posted on 25 Jul
Big vegetarians of the reef drive fish evolution
More than 6,000 fish species live on coral reefs across the globe A new study reveals the diets of reef fish dictate how fast different species evolve. The breakthrough adds another piece to the fascinating evolutionary puzzle of coral reefs and the fishes that live on them. Posted on 3 Jun
'Blue boats' rob Pacific reefs
The number of foreign fishing boats caught operating illegally has increased A flotilla of Vietnamese fishing boats with crews suffering in harsh conditions is stripping Pacific coral reefs of seafood as the poaching escalates to become an international human rights and security issue. Posted on 4 Dec 2019
Tracking baby fish for better reef management
Tracking the lives of thousands of tiny baby fish is no easy task A group of Australian scientists has created the world's first computer model that can accurately predict the movements of baby coral trout across the Great Barrier Reef. Posted on 3 Aug 2019
Breaking bread with rivals leads to more fish
Cooperation is key to most successful endeavours Dr Michele Barnes, a senior research fellow from the ARC Centre of Excellence for Coral Reef Studies, is the lead author of study published today that looks at the relationships between competing fishers, the fish species they hunt, and their local reefs. Posted on 7 May 2019
Ocean currents bring good news for reef fish
Study looks at how fish on a bleached coral reef get their food Researchers have discovered some good news for fish populations living on coral reefs hit by climate change. Posted on 25 Apr 2019
Murky water keeps fish on edge
Fish become anxious and more cautious when water quality is degraded by sediment Associate Professor Jodie Rummer, Principal Research Fellow at the ARC Centre of Excellence for Coral Reef Studies, based at JCU, says there is more sediment in coastal waters than ever before. Posted on 24 Dec 2018
150-million-year old flesh-eating fish
150-million-year old flesh-eating fish An international team of researchers have described a remarkable new species of fish that lived in the sea in the time of the dinosaurs in the late Jurassic about 150 million years ago. Posted on 28 Oct 2018
Finding Nemo's genes
An international team of researchers has mapped Nemo's genome In a breakthrough study led by the KAUST and the Coral CoE, researchers used high-tech sequencing tools to create one of the most complete genetic maps for the orange clownfish, a common reef inhabitant and star of the Disney movie, Finding Nemo. Posted on 20 Sep 2018
Apathy towards poachers widespread
Nearly half of fishers from seven countries had witnessed someone poaching in marine protected areas Dr Brock Bergseth from the ARC Centre of Excellence for Coral Reef Studies led the study. He said poaching is widespread in the world's marine protected areas, and that fishers have the potential to make or break a marine protected area. Posted on 31 Aug 2018
Marina Exchange FOOTER 1