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Old 29-03-2019, 03:14   #241
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Re: The Great Barrier Reef- resistant coral

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I think that the boffins have neglected to consider one factor; de-evolution ...
The authors of the second study, I cited, may have been getting at something “like” this.

However, for reasons that are not completely clear, the data show the long-term dynamics of evolution to be quite slow. Across a broad range of species, research has found that, for a major change to persist and for changes to accumulate, it took about one million years. The exact cause of these long-term, persistent evolutionary changes is not certain. The scientists said that climate change, in itself, does not appear to be a driving force, because many species have remained substantially unchanged over time periods when climates changed dramatically.

“The million-year wait for macroevolutionary bursts” ~ by Josef C. Uyeda et al.
https://www.pnas.org/content/108/38/15908
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Old 29-03-2019, 03:50   #242
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Re: The Great Barrier Reef- resistant coral

Evolution is directionless; de-evolution is at best an oxymoron, i.e. an organism can become simpler in response to a myriad of factors, but it is not de-evolving, it's evolving.

The rate of a species' evolution has been known to be variable for many years. Have a look at 'punctuated equilibrium'.
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Old 29-03-2019, 06:17   #243
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Re: The Great Barrier Reef- resistant coral

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Originally Posted by jimbunyard View Post
Evolution is directionless; de-evolution is at best an oxymoron, i.e. an organism can become simpler in response to a myriad of factors, but it is not de-evolving, it's evolving.
The rate of a species' evolution has been known to be variable for many years. Have a look at 'punctuated equilibrium*'.
Natural selection often leads to ever greater simplicity. And, in many cases, complexity may initially arise when selection is weak or absent.
“If you don’t use it, you tend to lose it.” Evolution often takes away rather than adding. For instance, cave fish lose their eyes, while parasites like tapeworms lose their guts.
Such simplification might be much more widespread than realised. Some apparently primitive creatures are turning out to be the descendants of more complex creatures rather than their ancestors. For instance, it appears the ancestor of brainless starfish and sea urchins had a brain.
Evolution myths: Natural selection leads to ever greater complexity
https://www.newscientist.com/article...er-complexity/

Evolution: 24 myths and misconceptions
Here is New Scientist’s guide to some of the most common myths and misconceptions about evolution.
https://www.newscientist.com/article...isconceptions/


* Some critics referred to the theory of punctuated equilibrium as "evolution by jerks", which reportedly prompted punctuationists to describe phyletic gradualism as "evolution by creeps."
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Old 29-03-2019, 16:15   #244
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Re: The Great Barrier Reef- resistant coral

We know from geological surveys that sea levels have often been higher in the past and from the depths of deposition of fossil reefs that the corals survived warming periods during these periods. Fairly solid evidence that the corals are going to survive anything we can do to the atmosphere. QED already without extensive abstract theories.
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Old 30-03-2019, 00:41   #245
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Re: The Great Barrier Reef- resistant coral

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....* Some critics referred to the theory of punctuated equilibrium as "evolution by jerks", which reportedly prompted punctuationists to describe phyletic gradualism as "evolution by creeps."
And, oddly enough, both seem to be accurate.
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Old 30-03-2019, 03:19   #246
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Re: The Great Barrier Reef- resistant coral

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Originally Posted by jimbunyard View Post
And, oddly enough, both seem to be accurate.
Yes, that's what makes the jibes funny.
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Old 30-03-2019, 04:01   #247
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Re: The Great Barrier Reef- resistant coral

‘Managed resilience’ not a successful strategy for conserving coral reefs, researchers find
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  • Coral reefs in protected areas that regulate fishing and pollution have declined to the same extent as reef systems in unprotected areas, according to recent research.
  • The study, published in the Annual Review of Marine Science in January, determined that ocean warming is the primary cause of the global decline of reef-building corals.
  • The researchers behind the study say their findings are consistent with a growing body of evidence that shows so-called “managed resilience” efforts, such as controls on fishing and pollution, don’t help coral reefs cope with the impacts of climate change.
https://marxiv.org/ugk4v
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Old 30-03-2019, 06:33   #248
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Re: The Great Barrier Reef- resistant coral

Woo-hoo! Now I can rip out the holding tank, antifoul with TBT and start fishing with dynamite.

Assuming, of course, that research isn't a pile of equine poo.
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Old 30-03-2019, 14:42   #249
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Re: The Great Barrier Reef- resistant coral

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Originally Posted by Reefmagnet View Post
Woo-hoo! Now I can rip out the holding tank, antifoul with TBT and start fishing with dynamite.

Assuming, of course, that research isn't a pile of equine poo.

And get them to scrap the GBR zones/rules.
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Old 30-03-2019, 14:47   #250
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Re: The Great Barrier Reef- resistant coral

"However, in a literature review, we find little empirical support for the notion of managed resilience."

So it's based on reading papers such as those produced by Hughes et al from JCU?
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Old 31-03-2019, 17:12   #251
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Re: The Great Barrier Reef- resistant coral

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The authors of the second study, I cited, may have been getting at something “like” this.

However, for reasons that are not completely clear, the data show the long-term dynamics of evolution to be quite slow. Across a broad range of species, research has found that, for a major change to persist and for changes to accumulate, it took about one million years. The exact cause of these long-term, persistent evolutionary changes is not certain. The scientists said that climate change, in itself, does not appear to be a driving force, because many species have remained substantially unchanged over time periods when climates changed dramatically.
A common mode of coral reproduction is asexual, all offspring are clones. Annual broadcast spawning sounds pretty hit and miss, especially when the majority of a given coral sp. on an isolated patch of reef is more than likely genetically identical.

Then there’s feeding and availability of food.

Bleaching doesn’t kill corals, starvation does. Climate change in this instance only really affects zooxanthellae. Luckily corals have a number of adaptable feeding strategies depending on available recourses (autotrophic & hetrotrophic).

The most common feeding strategy amongst corals is....well catching and eating (mainly) planktonic foods. All corals have evolved at least one mouth (sometimes more and yes some can live with non). Single polyp corals such as fungia or scolymia are much better at catching and eating larger more motile prey items than colonial colonies. We know higher water temp & co2 favours algae, phytoplankton and consequently zooplankton so not unreasonable to suggest climate chance would benefit corals that revert to this feeding strategy for the majority of their food right?

Photosynthesis via zooxanthellae ....most current reefbuilding corals obtain the majority of their energy this way. Higher light levels (less water depth) means lower zooxanthellae density is needed to provide adequate nutrition. This also means the coral has less ability to regulate photosynthesis via ejecting zoox without risking bleaching. There are also many corals that are azooxanthellate and don’t harbour symbiotic algae such as Tubastreae so by definition aren’t at risk of ever bleaching.

Then there’s capture of bacteria and ‘marine snow’ trapped in mucus and the absorption of dissolved organics.

Some corals use all feeding strategies to varying degrees, some only a couple. Importantly a genetic clone can vary their dependency on a strategy depending on their environment. Eg snap a colony in half put one 40 meters down, the other at 2 meters water depth. more sun light = greater reliance on photosynthesis, less reliance on hetrotrophic feeding ( ((was)) most successful strategy). Less light (deeper water) = less ability to provide adequate nutrition via photosynthesis once max zoox density is reached and greater reliance on planktonic food and absorption. See why so many corals reach for the light in current nutrient/plankton poor reefs?

So what’s the point?

Arguably corals don’t need to be genetically different to adapt over time to very different environmental conditions. They already have the tools. Possibly one reason they are unchanged for long periods of time even though their environment would have been substantially different. So corals ability to survive historicaly higher temp & co2 than today only suggests less reliance on photosynthesis as a survival strategy. Zooxanthellae can and do live independently of corals so what was their relationship like with corals 65 million years ago. What was the availability of other coral food sources like?

I’m not sure limited historical data necessarily gives us a full and accurate picture of why corals have survived so long unless we factor in all the other parameters for coral to survive.

I have little doubt that corals as a taxa will prevail. Even if 99% of coral species became extinct in the next 50 years there would still be 25-30+ different species. I sadly have little doubt that coral reefs as the unique complex environment we know, wont be around in the next 50-100 years....we’ll at least for the next few million years!
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Old 01-04-2019, 04:45   #252
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Re: The Great Barrier Reef- resistant coral

Indeed. Thanks for that Puddleduck.
In the face of climate change, recent discoveries are giving us hope that some corals can hang on longer than researchers imagined by resisting both rising temperatures and ocean acidification.

“Corals adapt photosynthetic rates to prevailing environmental conditions”
https://www.sciencedaily.com/release...0205115355.htm

“Diel versus time-integrated (daily) photosynthesis and irradiance relationships of coral reef organisms and communities”
~ by Yvonne Sawall, & Eric J. Hochberg
https://journals.plos.org/plosone/ar...l.pone.0208607

“Coral comeback: Reefs have secret weapon against climate change”
https://www.newscientist.com/article...limate-change/

“Heat-tolerant genes could help corals adapt to climate change”
https://www.newscientist.com/article...limate-change/
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Old 01-04-2019, 07:56   #253
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Re: The Great Barrier Reef- resistant coral

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Originally Posted by GordMay View Post
“Coral comeback: Reefs have secret weapon against climate change”
https://www.newscientist.com/article...limate-change/
For those who can't read this article because it's behind a paywall for them, here's another URL where it's at. However, this article has no images, and some of the text is screwed up, including its title "Not just a pretty face"

https://tribunecontentagency.com/art...a-pretty-face/
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Old 01-04-2019, 10:21   #254
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Re: The Great Barrier Reef- resistant coral

Thanks for the link, SailOar!
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Old 01-04-2019, 10:59   #255
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Re: The Great Barrier Reef- resistant coral

So why is it that I keep hearing & reading -- most notably from the BBC -- that coral "bleaching" is synonymous with coral "death"? But then I read from some of these links & elsewhere that bleaching is more of a temporary phenomenon that coral often recovers from, and that it has more resiliency to warmer temps then previously thought? Equating coral bleaching with "death" has a permanency to it that sounds quite alarming. Is that actually the point, or is it more a matter of semantics? Or has the science changed it's view on the issue over the past few years?
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