The tropical corals of Rottnest Island appear to be thriving at the extreme limits of their geographical position despite lower and more seasonally variable water temperatures.
Claire Ross, a PhD student at The University of Western Australia, measured two reef-building species of stony coral at Rottnest Island just off the coast of Perth, the southernmost limit for these tropical corals.
“I was surprised to find that these corals were growing all year round at rates comparable to corals growing in the tropics,” reveals Claire. “As winter growth rates were higher than expected, it is likely that these corals acclimatise to lower levels of light and lower water temperatures in this region.”
Coral communities in high-latitude areas of WA (i.e. further from the equator), like Rottnest Island, are unique natural laboratories in which to study the effects of warming temperatures on the growth of tropical coral species.
“Many of these potential high-latitude refuges in WA have fossilized coral reefs,” explains Claire. “This signifies the past suitability of those areas to support more extensive coral growth during previous warmer geological periods.”
The capacity for reef-building tropical corals to flourish in these potential refuges has reef-wide implications for the future survival of modern coral reefs under carbon dioxide-driven ocean warming.
It appears that extensive coral growth is once again occurring at Rottnest Island, which may provide an essential ‘safe haven’ for tropical corals in the future.
Claire presented her research at Fresh Science WA 2015. Fresh Science is a national program that helps early-career researchers find and share their stories of discovery. Over 20 early-career researchers nominated for Fresh Science WA, which was held at the Western Australian Museum (training) and the Brisbane Hotel (public challenge event) and was supported by the Western Australian Museum, Curtin University, Edith Cowan University, Murdoch University, the University of Western Australia and the University of Notre Dame, Australia.
This research involved co-authors J.L Falter, V. Schoepf and M.T. McCulloch from The University of Western Australia (https://peerj.com/articles/781/; Peer J).
Contact: Claire Ross, PhD Student – The University of Western Australia