Scientists have taken a rare look at the depths of the Great Barrier Reef and have discovered they’re teeming with a kaleidoscope of life.
And they say conservation planners should take into account their findings to better protect the international icon.
ARC Centre of Excellence for Coral Reef Studies at James Cook University PhD candidate Tiffany Sih led the study, which used Baited Remote Underwater Video Stations (BRUVS) and multi-beam sonar to examine the reef down to 260 metres.
“The ecology of deeper habitats along the Great Barrier Reef has rarely been investigated. While we know habitat like coral is important for shallower fish species, there was little understanding of how important reef habitat is to fish in deeper environments,” said Ms Sih.
She said the lack of information was due to the expense of doing research at these depths, which often requires specialist divers, remotely operated submersibles or mini-submarines.
Instead, the team sampled 48 sites between 54 and 260 metres deep in the central GBR using sonar and a relatively simple BRUVS rig, which attracts fish with bait and films them.
“We found the ecology of deeper reef fish communities is fundamentally different from those found at shallower depths. Depth and reef composition was important, but habitat preferences clearly had a role in determining the distribution of fish species.
Both the living components of the habitat – such as algae, soft corals and sponges, as well as big boulders or mud flats – contribute to the structure and complexity of the reef, which has an effect on what kind of fish you find there,” said Ms Sih.
She said when the rules around fishing in the Great Barrier Reef Marine Park were determined over a decade ago, less environmental data was available for the deeper habitats.
“They took into account what they did not know, and allowed for some uncertainty, by designating some of the deeper areas as no-take zones and zones where certain types of fishing, like bottom-trawling, were banned. But now the technology exists where we can map the deeper areas and fully document the fish community,” said Ms Sih.
She said that in the future it will be important to compare deeper fish communities in the Great Barrier Reef Marine Park and to consider deeper reefs as essential neighbourhoods where communities of fish thrive.
Contact: Tiffany Sih (now located in Ocean Grove, Victoria)
M: 0432 528 008
Professor Mike Kingsford (Professor Kingsford works at JCU’s Townsville campus).
M: 0438 731 694
T: 07 4781 4312
Paper: Sih TL, Daniell JJ, Bridge TC, Beaman RJ, Cappo M, Kingsford MJ, (2019). Deep-Reef Fish Communities of the Great Barrier Reef Shelf-Break: Trophic Structure and Habitat Associations. Diversity. 11(2):26.
Link to journal here