Delving Deep for Answers
The XL Catlin Seaview Survey (CSS) is a global program to document marine biodiversity. Branded as “Google Street View goes underwater”, the program has featured prominently in recent media. Part of the CSS is a study of mesophotic coral reefs known as the “deep reef” – a largely undocumented reef habitat beyond the normal scuba diving depth of 30 to 150 meters.
Using specialised deep diving and remote operated vehicles (ROVs), researchers from University of Queensland and Dr Paul Muir, Research Officer and Collection Manager of Corals at the Museum of Tropical Queensland have now begun documenting the mesophotic zone of the Great Barrier Reef, arguably the last great undocumented Queensland habitat.
Dr Muir said that recent studies indicate the mesophotic reefs are quite extensive and have found that coral habitat on the Great Barrier Reef may be up to 50 per cent larger than previously thought, if mesophotic reefs are included.
The Museum of Tropical Queensland was invited to join the survey to provide expertise in the areas of coral taxonomy and ecology. Dr Muir was able to reap the benefits of training in advanced diving techniques and operating an ROV, part of which was funded by the Queensland Museum Network’s Professional Development Committee.
Dr Muir participated in a recent CSS expedition to the largest and most remote system of coral atolls in the world: the Chagos Islands.
“This string of coral cays is situated in the central-west Indian Ocean and has a controversial history: the local inhabitants were removed to terrible cultural detriment in the 1950s by the UK and US military as part of an exclusion zone around a large new military base at Diego Garcia,” said Dr Muir.
“The presence of this base does mean that Chagos Islands now provide a unique natural laboratory: a large remote reef system with no people: virtually zero impacts from fishing, runoff from agriculture and sewage, sediments from development and all the other things that go with early 21st century humans.”
Dr Muir said that the reefs are so remote and off limits that the expedition relied upon the UK and US military for air transport into the area and for the expedition vessel.
“The lack of a human presence was quite noticeable whilst diving. Large fish such as coral trout are normally scarce and shy, however in the Chagos they were abundant and curious- we literally had to push them out of the way to work on the corals!”
The Chagos reefs are also of great interest to science because they have undergone two extreme high seawater temperature events in the last 20 years, which caused mass coral bleaching and death. These events are predicted to become more common in the near future and pose a significant threat to the Great Barrier Reef.
Dr Muir explains that the central-west Indian Ocean is thought to be “ahead of the game” due to unusual ocean circulation and so the Chagos gives us a glimpse into the future – how large reef systems cope with bleaching events, which coral species are most vulnerable, and how species composition may change.
“This was also an opportunity to enhance our collections,” said Dr Muir.
“The Queensland Museum Network has one of the largest coral collections in the world, spanning most reef areas, and we were able to document and collect the unique and isolated Chagos coral fauna,” he said.
“Our collection also included samples for molecular biology (DNA) analyses and we will be working closely with the University of Queensland over the ensuing months to unlock some of the secrets of this unique area.”
Dr Muir explains that the Queensland Museum Network collects coral in order to be able to keep a unique record of reef corals which may become locally and even globally extinct in coming decades.
“The collection is a powerful tool for researchers to tackle questions of global importance. For example, we have recently had a paper published in the prestigious journal Science. The research uses the coral collection to answer some fundamental questions about global coral distribution and ecology and how this may change in response to warming oceans.”
This project also illustrates the importance of collections such as these in that they measure change over time, which helps to better inform policy decisions around environmental management.
Image credit: The Shallow Reef XL Caitlin Seaview Survey team preparing for a transect. Three synchronized, high resolution DSLR ca,eras mounted on the nose of the instrument take approximately 900 images over a single 1.8 km linear transect. Images courtesy of XL Catlin Seaview Survey. www.catlinseaviewsurvey.com
Article originally appeared in Antenna, Queensland Museum Foundation Magazine, Spring 2105.
Contributor Dr Paul Muir.