Assoc. Prof Maria Dornelas (University of St Andrews, Scotland), Assoc. Prof Joshua Madin (University of Hawaii) and fellow collaborators have been making annual visits to LIRS since the early 2000s during which they monitored the changing ecology of coral reef communities. Their trips coincide with the annual coral spawning event. Their long-term and detailed data sets are enormously valuable and are unmatched anywhere in the world. Most recently, this data captures the impacts on coral communities due to two devastating cyclones (2014, 2015) and two mass coral bleaching events (2016, 2017) . The process of reef recovery from these events is now a major focus of their research.
For the past few years, the project was funded by a John Templeton Grant. That initial funding has now finished but we are delighted to report that the Charles Warman Foundation, a long term supporter of LIRRF is providing the additional funding required to continue for the next 3 years.
In the post below, Maria shares background information on their project and encouraging observations following her November 2019 trip to LIRS. In early 2020 her research team will return to monitor various sites and specifically to look at the amount of settlement of corals after the November/December spawning events. We look forward to sharing their ongoing observations with you.
Coral reefs are built by corals, which shape the environment in which they live through the rocky structures they build. Corals are key examples of how organisms change the environment in ways that favour themselves – a process called niche construction. For example, the complex structures that corals build increase the chances that coral larvae settle on the reef. Positive feedback loops such as this are a possible cause of the high concentration of life we find on coral reefs. However, coral reefs are at risk, as cyclones and marine heatwaves become more common with climate change. In this project, we aim to understand the mechanisms that protect corals during disturbances and allow them to recover afterwards.
Disturbances such as cyclones and thermal bleaching harm corals, and so undermine the foundation of coral reef ecosystems. Yet, both the harm caused by these disturbances and the recovery that follows are patchy in their effects. That is, some reef patches are more affected than others, and some patches bounce back faster than others. We propose that niche construction – that is coral-built modifications of the environment – offers protection from disturbances and maximises recovery potential. Lizard Island’s dramatic recent history of severe disturbances and the ecological and reef geometric data we have collected over the past five years present a precious opportunity to test our hypothesis.
We have been mapping reef changes across 21 sites around Lizard island since 2015. At each site, we build 3D maps of a circular patch of the reef, 12m wide, which we call reef records. The survey involves swimming a camera rig, outwards from the centre in a spiral fashion (as if we were playing a vinyl record backwards – hence the name), while taking around 2000 photos.
The images are processed by a Structure-from-Motion software pipeline, at the research station to construct photo mosaics and 3D models of the reef. We then print these on to underwater paper and take them back to the reef to map underwater the locations of every coral we can see. We also use lots of small data-loggers to keep track of temperature, light and flow around our survey sites.
Data from our latest trip (November-December 2019) is still being processed, but already we can see a huge difference relative to previous years. For instance, the number of corals has roughly doubled across the island. Excellent news, given the collapse in numbers and species of corals we had seen following the sequence of two cyclones and two bleaching events between 2014 and 2017. The corals are still very much low in abundance and small in size, but the high numbers of young corals give us hope that the reefs may be able to recover faster than anticipated.
Dr Maria Dornelas
University of St Andrews, Scotland