Taryn Foster is a PhD student in the ARC Centre of Excellence for Coral Reef Studies. She recently attended the ACRS Conference on Daydream Island and was awarded the Vicki Harriott Award for best presentation.
The impacts of climate change and ocean acidification on corals, the major reef-builders and marine habitat providers, are of significant global interest. There is very little information however, on how these stressors will impact on the calcification of juvenile corals, where there is the potential for early post-recruitment growth and subsequent survival to be a bottleneck in recruitment success.
This study took place at the remote, sub-tropical Abrolhos Islands, in Western Australia and investigated the impacts of acidification and elevated water temperature on the ability of juvenile corals to form their skeletons. Adult colonies of a common plate coral species (Acropora spicifera) were collected and spawned in aquaria. The larvae were then cultured and newly settled coral recruits were grown for one month under treatment conditions. The “mobile lab” consisted of 24 temperature and CO2 controlled esky’s and a generator to power the whole system, as the initial experiment was conducted in a cray fisher’s jetty shed!
3D X-ray microscopy was then used to provide a range of new measures of juvenile skeletal deposition and expose structural deformities in the skeleton that have not previously been visible. This work demonstrated that newly settled coral recruits are highly sensitive to acidification and are unable to build structurally viable skeletons under predicted near-future elevations in CO2.
In contrast, elevated temperature had a positive effect, partially mitigating the negative effects of high CO2 on juvenile skeletal formation, a response that is likely unique to sub-tropical coral recruits and may indicate some resilience to future temperature elevations.