Coral

Soft coral, cup coral, sponges and ascidians from Komodo National Park
Soft coral, cup coral, sponges and ascidians from Komodo National Park

Coral reef biodiversity predicted to shuffle, not decline

Rather than causing a collapse of biodiversity, the dual stressors of ocean warming and acidification could instead lead to significant changes in the relative abundance of species, resulting in a shuffling of coral reef community structure, according to a new study by researchers from University of Hawai'i.

Sprawling coral reefs are complex ecosystems that are teeming with life and most of this biodiversity consists of tiny organisms living deep within the three-dimensional reef matrix.

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.

Great Barrier Reef corals (Kyle Taylor / Flickr / CC BY 2.0)
Great Barrier Reef corals (Kyle Taylor / Flickr / CC BY 2.0)

Deciphering the corals' scents

Last December, marine biologist Caitlin Lawson made her way to the Great Barrier Reef.

Like countless others, she was there for the annual spawning of the corals. However, she was armed, not with expensive photographic equipment, but small plastic containers rigged with tubing.

Her mission? To collect the gaseous chemicals released by the corals (as well as their algal and bacterial symbionts) before, during and after the spawning event.

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.

Help protect the Coral Reefs

Our coral reefs are now under threat not only from the global warming, pollution and exploitation but also by the conduct of divers in these sensitive areas. The reefs are now calling for our protection both when we dive and as contributors to the ongoing struggle to preserve these unique ecosystems for future generations.

The coral sanctuary is a wildlife hotspot, teeming with spinner dolphins (shown in this archive photo) and boasting rare species, including prehistoric fish and dugongs.

Flourishing coral sanctuary discovered off East Africa

The coral sanctuary is a wildlife hotspot where species are thriving despite warming events that have killed their neighbours

The coral refuge, which stretches from Shimoni, 50 miles south of Mombasa, in Kenya to Dar es Salaam in Tanzania, is fed by cool water from deep channels formed thousands of years ago by glacial runoff from Kilimanjaro and the Usambara mountains. Outside that area, the corals are bleached and dying. But inside the area, of around 400 sq km [150 sq miles] they retain their colour and their health.

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.