Coral Reef Island Initiation and Development Under Higher Than Present Sea Levels

Higher sea levels will cause some coral islands to GROW

H. K. East et al.

Abstract

Coral reef islands are considered to be among the most vulnerable environments to future sea level rise. However, emerging data suggest that different island types, in contrasting locations, have formed under different conditions in relation to past sea level. Uniform assumptions about reef island futures under sea level rise may thus be inappropriate. Using chronostratigraphic analysis from atoll rim islands(sand- and gravel-based) in the southern Maldives, we show that while island building initiated at different times around the atoll (~2,800 and~4,200 calibrated years before present at windward and leeward rimsites, respectively), higher than present sea levels and associated high-energy wave events were actually critical to island initiation. Findings thus suggest that projected sea level rise and increases in the magnitude of distal high-energy wave events could reactivate this process regime, which, if there is an appropriate sediment supply, may facilitate further vertical reef island building.

Plain Language Summary

The habitability of reef island nations under climate change is a debatedand controversial subject. Improving understanding of reef island responses to past environmental changeprovides important insights into how islands may respond to future environmental change. It is typically assumed that all reef islands will respond to environmental change in the same manner, but suchassumptions fail to acknowledge that reef islands are diverse landforms that have formed under different sealevel histories and across a range of settings. Here we reconstruct reef island evolution in two contrastingsettings (in terms of exposure to open ocean swell) in the southern Maldives. Important differences in islanddevelopment are evident between these settings in the timings, sedimentology, and modes of islandbuilding, even at local scales. This implies that island responses to climate change may be equally diverse and site-specific. We present evidence that island initiation was associated with higher than present sea levelsand high-energy wave events. Projected increases in sea level and the magnitude of such high-energy waveevents could therefore recreate the environmental conditions under which island formation occurred. If thereis a suitable sediment supply, this could result in vertical island-building, which may enhance reef island future resilience.

SOURCE

Could our reefs be saved after all? Weed-like cauliflower coral has evolved unique immunity genes that means it could survive global warming

So a very vigorous coral is a "weed".  The Green/Left never miss a chance at negativity.  And saying it has developed "immune" responses to survive is a stretch.  Starfish, lowered water levels, and  unexpected heat variations are the big enemies of coral, not viruses and bacteria

A common coral has evolved unique strategies to cope with environmental change. Scientists say the cauliflower coral - which is traditionally thought of as a weed - could be one of the only corals to survive dramatic changes in the climate.

As one of the most abundant and widespread reef-building corals in the world it could be crucial to the future survival of the world's reefs, scientists found.

Researchers from the University of Miami say the common coral species might have evolved unique immune strategies to cope with environmental change.

Roughly 30 per cent of the cauliflower coral's (Pocillopora damicornis) genome was unique compared to several other reef-building corals.

This adaptation could be crucial for the long-term survival of coral reefs as climate change and ocean acidification continue to ravage the oceans.

'This coral is traditionally thought of as a weed, and yet it may be one of the last corals to survive environmental changes such as climate change,' said senior author of the study Nikki Traylor-Knowles, an assistant professor of marine biology and ecology at the University of Miami.

To conduct the research, scientists extracted and sequenced the genomic DNA from two healthy fragments and two bleached fragments of P. damicornis.

Their genome was then compared to publicly available genomes for several other coral species.

'The study shows that this is an important coral with a very complex and unique immune system, which may explain why it is able to survive in so many different locations,' said the paper's lead author Ross Cunning who is now a researcher at Shedd Aquarium.

The results suggest that the evolution of an innate immune system has been a defining feature of the success of hard corals like P. damicornis.

The immune system of corals, like humans, is vital to protect overall health and deal with changes in its surroundings.

If an animal has a stronger immune system then it will be better equipped to deal with environmental changes.

These new findings, published in Scientific Reports, suggest that some corals have many more immunity genes than would be expected.

'This study helps us better understand how corals deal with stress,' said Dr Traylor-Knowles.

'Its complex immune system indicates that it may have the tools to deal with environmental change much more easily than other corals.'

SOURCE 


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Grim reef bleaching forecast

Prophecies, prophecies. They do this forecast most years.  I come from Australia's Far North, adjoining the reef, and I can in fact remember such earnest forecasts from when I was a kid --60 years ago.  But the reef is still there, much the same as ever.  It has ups and downs but it always bounces back.  It has bounced back recently in fact, something not mentioned below -- which is why they stick to prophecy

Predictions that the Great Barrier Reef could suffer severe coral bleaching by the end of summer is an urgent warning for the Federal Government to take immediate climate action, says the Australian Marine Conservation Society.

The US National Oceanographic and Atmospheric Administration’s (NOAA) tentative forecast, out today, predicts the entire reef has a 60 percent chance of being subject to "bleaching alert level one"—meaning bleaching is likely— by March 2019, with possible coral mortality in some areas.

“How much more of the Great Barrier Reef has to die before the Federal Government acts on climate change?,” said AMCS spokesperson Imogen Zethoven.

“While our Reef is in danger, our politicians continue to ignore the issue of climate change with no credible plan to reduce pollution.

Parts of the southern half of the Reef are on higher alert with coral mortality likely in some areas, according to NOAA. An El Niño event could increase the odds of a severe bleaching event.

“The Reef is already suffering heat impacts. Add drought, bushfires and heatwaves into the mix and all Queenslanders, including our marine life, are in for a tough summer,” said Zethoven.

“The government’s claims that it is looking after the Reef—and the millions of taxpayer dollars spent on this—ultimately count for very little if it continues to ignore the greatest threat to the reef.

“By failing to protect the Reef, the Federal Government is also gambling with the 64,000 jobs that are dependent on the Reef, and the $6 billion that it generates every year for the Queensland economy.”

“The Government knows what the solutions to this are all too well: no new coal mines, including Adani’s monstrous Carmichael mine, a rapid transition to renewable energy, a phase out of all coal-fired power stations by 2030 and an immediate end to all fossil fuel subsidies.”

“But instead of acting on these recommendations, the government continues to pander to the demands of the fossil fuel industry instead of delivering a cleaner, safer future for Australia.

“The Government is on notice ahead of the next election. Australians want the Government to protect the Reef and its amazing wildlife. The time to act is now.”

Greenie Media release. Interviews available from Imogen Zethoven, a Greenie from way back. 0431 565 495