Tabular Acropora: A Coral Hero That Could Save Reef Beds
A new study of corals has shown that table corals or Tabular Acropora coral can help repopulate a barren marine ecosystem faster than any other species of coral. This discovery is of immense significance as it allows researchers to carefully pick reef-building species to manage coral conservation projects.
The new study is led by the Australian Institute of Marine Science (AIMS) in collaboration with the Great Barrier Reef Marine Park Authority, the University of Queensland, and The Nature Conservancy. The team studied the impact that tabular acropora have when used in coral restoration projects in the Great Barrier Reef Australia.
This amazing coral species has been dubbed as “extraordinary ecosystem engineers.” When used as the primary reef-building species, tabular Acropora helped regenerate life a whopping 14-times faster than any other coral species. The team believes that using this species could drive coral restoration projects 2 decades into the future.
AIMS scientist and lead author Dr Juan Carlos Ortiz said the research showed overall reef recovery would slow considerably if table corals declined or disappeared on the Great Barrier Reef.
“Table corals are incredibly fast growing. Habitats in exposed reef slopes recover from disturbances at a rate 14 times higher – that’s more than two decades faster – when table corals are abundant,” he said in a press release on the AIMS website.
“Their large, flat plate-like shape provides vital protection for large fish in shallow reef areas and serves as a shelter for small fishes, with some species almost entirely dependent on table corals. Even after death, these corals provide value, as their skeletons are the preferred place for young corals of all types to settle,” he added.
The study published in journal Conservation Letters found that this species has a unique combination of characteristics that boosted barren ecosystems. They provided valuable ecological functions, are among the most sensitive coral types and, most importantly, their role was threatened by a low diversity of species which have this growth form.
Focusing on protecting and managing table corals could become a conservation goal, given that they help efforts immensely. This could allow for ecosystem management and identifying areas of immediate concern, according to the team.
“Table corals are still frequently seen on outer reefs, but their presence shouldn’t be taken for granted as they are vulnerable to combined impacts,” Great Barrier Reef Marine Park Authority’s Assistant Director and study co-author Dr Rachel Pears said.
“These corals do not handle intensifying thermal stress well, are easily killed by anchor damage, highly susceptible to diseases, and are the preferred meal for crown-of-thorns starfish. The good news is there are tangible actions we can take to protect these corals such as targeted crown-of-thorns starfish control and anchoring restrictions.”
Though it is not an all-encompassing solution, it is clear that tabular corals play a vital role in ecosystem regeneration. Though they do not help improve the bio-diversity in a region (they do not impact the growth of other species of coral), they did help start the repopulation process. This helped the region recover by bringing in fish and creating a suitable environment that helped other species flourish. University of Queensland’s scientist and study co-author Professor Peter Mumby said while table corals promoted high rates of recovery, they did not necessarily bring high biodiversity.
“We know table corals do a big service for these reefs, but it’s not a silver bullet for recovery,” he said. Protecting table corals could be part of a suite of actions that look at reef recovery, with other management focused more specifically on protecting biodiversity.”
Impact of Study
The main issue plaguing reef systems across the world is the slow recovery rate. Climate change is causing mass bleaching events causing corals to die faster than they can regenerate, causing plunging numbers, diversity, and barren coasts. Corals are integral to marine life and they house over 70 percent of the fish species found in our oceans.
Using a coral that allows for faster regeneration is the need of the hour. There are many studies that show how corals require special regeneration processes and man-made structures to grow on before being reinstated to the ocean floor. But all these efforts are in vain if they do not regenerate fast enough.
Using species like tabular acropora can allow for a greater chance of survival, making it vital for coral conservation. Identifying clusters of table coral can allow researchers to target areas where faster regeneration is naturally possible. Then the job becomes much simpler with focus being improving coral diversity.
The research drew on decades of data from AIMS long term monitoring program, revealing coral reef habitats took up to 32 years to recover, from 5% coral cover to 30% coral cover, where table corals had not recolonised after disturbances.
But in areas with table corals, the habitats recovered to 30% coral cover in just seven and a half years. This extraordinary ability to fuel coral growth makes table coral integral for future restoration efforts like coral enhancement or assisted colonisation.
“Anyone who has been on the mid-shelf or offshore areas of the Great Barrier Reef would have seen table corals,” Dr Ortiz said. We can think of table corals as the iconic charismatic ‘mega coral’ of the Great Barrier Reef, just like whales, turtles and dolphins are the Reef’s iconic charismatic megafauna.”
This is known as resistance-based population management, where resilience is valued and used to trigger further repopulation in marine environments. But the study also warns researchers of considering this a “silver-bullet” for coral conservation. There needs to be an efficiency study that accounts for costs and benefits of such before any change is implemented.
There are several other ste[ps that could further aid table corals in restoration efforts. Managing the population of crown-of-thorns starfish control, anchoring restrictions and protection for tabular corals on reefs identified as essential for their larval dispersal. In addition, targeted communications about the critical importance of these highly recognizable corals may boost community support and participation in their protection.