A new future for corals

Are coral reefs condemned to disappear? During the first decade of the 21st century, the intensification of cyclones, the phenomenon of coral bleaching due to ocean warming, outbreaks of a coral-eating starfish and coral diseases left us with this fear. But today, scientists are revising their pessimistic forecasts from the previous decade. In fact, recent research works show that, while numerous coral species have indeed been declining for more than 30 years, other are holding firm or even increasing in abundance. Consequently, some reefs have recently managed to recover. 

Expanding coral genera

During a vast international study over fifteen years, IRD researchers and their partners observed the ecological development of seven coral reefs throughout the world: two in the Caribbean, in Belize and in the American Virgin Islands, and five throughout the Indo-Pacific Ocean in Kenya, Taiwan, Hawaii, Moorea and the Great Barrier Reef in Australia. Consequently, the scientists have shown the increase of certain genera, like the Porites reef corals, real reef builders that can resist temperature rises well.

They have also put these recent changes into perspective with regard to past events recorded in fossil reefs, showing that the abundance and structure of coral populations have already varied greatly over the course of past millennia.

Towards new underwater landscapes

These new data have enabled them to refine their mathematical models and to revise their forecasts for the coming decades. As ocean temperatures continue to rise, a subset of “winning” species will thrive: those that have the greatest heat tolerance, the best population growth rates or the greatest longevity. These species should progressively populate the planet’s reefs, until they dominate them entirely.

Consequently, the underwater landscapes of the future will be very different to the ones that have been known for millennia. However, much remains to be discovered regarding this new coral fauna and its features. One question in particular remains: will these new eco-systems continue to meet the needs of the populations who depend on them?

SOURCE

Coral bleaching not a response to temperature changes

Regional coral responses to climate disturbances and warming is predicted by multivariate stress model and not temperature threshold metrics

Timothy R. McClanahan et al.

Abstract

Oceanic environmental variables derived from satellites are increasingly being used to predict ecosystem states and climate impacts. Despite the concerted efforts to develop metrics and the urgency to inform policy, management plans, and actions, few metrics have been empirically tested with field data for testing their predictive ability, refinement, and eventual implementation as predictive tools. In this study, the abilities of three variations of a thermal threshold index and a multivariate stress model (MSM) were used to predict coral cover and community susceptibility to bleaching based on a compilation of field data from Indian Ocean reefs across the strong thermal anomaly of 1998. Field data included the relative abundance of coral taxa 10 years before the large-scale temperature anomaly, 2 years after (1999–2000), and during the post-bleaching recovery period (2001–2005) were tested against 1) a multivariate model based on 11 environmental variables used to predict stress or environmental exposure (MSM), 2) estimates of the time until the current mean maximum temperature becomes the mean summer condition (TtT), 3) the Cumulative Thermal Stress (CTS) for the full satellite record, and 4) the 1998 Annual Thermal Stress (1998 ATS). The MSM showed significant fit with the post-1998 cover and susceptibility of the coral community taxa (r2 = 0.50 and 0.31, respectively). Temperature threshold indices were highly variable and had relatively weak or no significant relationships with coral cover and susceptibility. The ecosystem response of coral reefs to climatic and other disturbances is more complex than predicted by models based largely on temperature anomalies and thresholds only. This implies heterogeneous environmental causes and responses to climate disturbances and warming and predictive models should consider a more comprehensive multiple parameter approach.

McClanahan, T.R., Maina, J. & Ateweberhan, M. Climatic Change (2015) 131: 607. doi:10.1007/s10584-015-1399-x

Another stupid Greenie prophecy:  "The Reef will never be the same again"

This is just straight Greenie propaganda, with no regard to all the facts.  The GBR has had some bleaching events lately but it is nothing compared to Bikini Atoll, which had a thermonuclear device exploded above it.  And Bikini coral is thriving again.  If coral on Bikini can survive that, why should not the GBR survive infinitely lesser stressors?

And attributing the isolated bleaching to global warming is just assertion.  They offer no evidence for it.  The best evidence is that it is due to sea-level changes, not ocean warming.

It does seem that the 2015/2016 summer bleaching was repeated in summer this year (2016/2017).  Since water levels change only slowly, that is to be expected. 

And note that while they are busily attributing the bleaching to global warming -- they give not a single number for either the global water temperature or the North Queensland water temperature. 

So let me supply some numbers: NASA/GISS Tell us that the global December 2016 temperature (mid-summer) was .77, which was DOWN on December 2015 (1.10)and even slightly down on 2014 (.79).  So in the period at issue, there was NO global warming.  So the guys below are lying through their teeth.  They say that the bleaching was caused by global warming but there WAS no global warming in the period concerned.

And they also don't give numbers for sea levels in the area.  They are zealously hiding the real cause of the bleaching


THE biggest jewel in Australia’s tourism crown will never look the same again — and to fix it, Australia needs a worldwide hand.

Made up of 3000 individual reef systems, the Great Barrier Reef is the world’s largest living organism. It is home to 300 species of coral and a vast array of fish, molluscs, starfish and other marine life.

The Reef also supports a $6 billion tourism industry that provides employment for 69,000 people — all of which is in strife if environmental degradation causes significant, widespread harm.

Already back-to-back coral bleaching episodes have taken their toll, wiping out nearly 600km of coral mostly in the far north.

Caused by rising ocean temperatures that kill food-generating algal organisms inside the coral, no one can say with any confidence that bleaching will not become an annual event.

Even more worrying, scientific data suggests a further two-degree increase in ocean temperatures would wipe-out most of the hard corals.

The man in charge of the Reef Recovery program at the Great Barrier Reef Marine Park Authority, Dr Mark Read, concedes it will never look the same again.

Although some corals will build up a resilience to warmer temperatures, a number of species are facing extinction.

"I think it’s going to end being a real mosaic," said Dr Read.

"Some parts of the Reef are going to look more classic — hard coral-dominated — that we’re familiar with while other parts will be less dominated by hard coral and more dominated by soft coral and algae."

While natural habitats are destined to change over time, Dr Read says in the Reef’s case, mankind has contributed to the "current accelerated period of heating" causing coral bleaching.

"We are talking about a global phenomenon," Dr Read said.

"(Coral bleaching) is happening all around the world where you have hard coral. The Great Barrier Reef has been hit particularly hard, so it’s front of mind."

Among the strategies being used by his team to aid in the Reef’s recovery, are ensuring activities in the area do not adversely impact the delicate marine environment; tackling the insidious Crown of Thorns starfish; improving water quality and reducing the volume of debris that finds its way into the massive water park.

Together those initiatives will make a difference but Dr Read admits they won’t prevent more episodes of coral bleaching.

"In terms of dealing with the warming per se, that is something that needs to be tackled at that global level," he said.

"What we do, and what we can do is reduce as many of the direct pressures on the Reef to enhance its capacity to bounce back."

Those who make a living from the Reef are watching the situation with some trepidation.

Despite chalking up their best tourism season since 1997 in 2016, long-term operators know the back-to-back coral bleaching events that have received global coverage will eventually take their toll.

SOURCE