Coral

Table corals can regenerate coral reefs at a very fast rate.
Table corals can regenerate coral reefs at a very fast rate.

Why table corals matter in reef regeneration

Remember those large table corals (tabular Acropora) at the Great Barrier Reef?

A new study had shown them to be “extraordinary ecosystem engineers”, with the ability to regenerate coral reef habitats at the iconic reef at a rate 14 times higher—more than 20 years faster—than any other coral type.

In essence, the research indicated that overall reef recovery would slow significantly if these corals declined or disappeared at the reef.

Vlad Karpinsky / CC BY-NC-ND 2.0
File photo: Reef scene in Fiji. Source: Vlad Karpinsky / CC BY-NC-ND 2.0

Fiji's coral reefs rebounds

On 20 February 2016, tropical cyclone Winston struck Fiji. It was described as the most destructive cyclone ever to strike in the Pacific. With winds of up to 280km/h, the coral reefs in the Namena Marine Reserve and Vatu-i-Ra Conservation Park off Fiji were completely destroyed.

To understand how cyclones affect coral reefs and how fast the reefs recover, the team at Wildlife Conservation Society (WCS) Fiji conducted three surveys at different times—one month after, six months after and in December 2020 (more than four years after the cyclone).

Corals in the Pacific Ocean
Corals in the Pacific Ocean

Coral count leads to reassessment of extinction threat

There are currently about half a trillion corals in the Pacific. Of the species studied, two-thirds of the coral species have population sizes exceeding 100 million colonies, while 20 percent of the species have population sizes that are more than a billion colonies.

“We need to know the abundance of a species to assess its risk of extinction,” said lead author Andy Dietzel from the ARC Centre of Excellence for Coral Reef Studies at James Cook University (Coral CoE at JCU).

Natural bleaching susceptibility is manifested in the biochemistry of both the coral and its algal symbiont.

Unravelling how some corals resist bleaching

Researchers at Michigan State University and the University of Hawaii at Manoa have been uncovering clues as to why some corals bleach while others are resistant, information that could help reefs better weather warming waters in the future.

The team analysed the biochemistry of corals using mass spectrometers to understand what set resistant corals apart from susceptible ones. The scientists found that two different communities of algae lived within the corals. Inside the algae cells were compounds known as lipids.

Coral larvae being collected at Palmyra Atoll National Wildlife Refuge. This allows researchers to enumerate the number of baby corals settling on a reef.

Corals seek cooler pastures in subtropical waters

Coral reefs have been seeking new pastures, as rising temperatures heat up their natural habitats.

Over the last four decades, coral reefs have been progressively shifting their homes from equatorial waters to more temperate regions.

The reason? Climate change.

“Climate change seems to be redistributing coral reefs, the same way it is shifting many other marine species,” said Nichole Price, a senior research scientist at Bigelow Laboratory for Ocean Sciences and lead author of the paper on the topic.

The staghorn coral (Acropora cervicornis) is a branching, stony coral with cylindrical branches ranging from a few centimetres to over two metres in length and height.

Coral restoration projects show promise in Florida Keys

Reef-building staghorn coral (Acropora cervicornis) was abundant and widespread throughout the Caribbean and Florida until the late 1970s.  The fast-growing coral formed dense thickets in forereef, backreef, and patch-reef environments to depths over 20 m.