Talk:Coral bleaching

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GBR[edit]

The Great Barrier Reef (GBR) has been described as “one of the most amazing wonders of the natural world.” With its increddible beauty, tourists world wide flock to see the natural wonder. The Great Barrier Reef is really one of the most magnificent creations on earth.

As we are regularly reminded in the news and by the government and other organizations that the reef is under many possibly fatal dangers. These include pollutants run off, over fishing in some areas, tourism vessels creating water pollution, tourists sun creams killing corals, tourists inadvertently braking corals, tourist and fishermens ankers braking large areas of coral, possible oil spills by tankers going through the great barrier reef with loads of oil and fuels and the threat of global warming. All of the risks could lead to this precious ecosystems death.

But coral bleaching seems to be the worst problem that reef is currently facing. Thought to be caused by run off from the numerous cane fields the poisons affects the corals as well as the warming temp of the sea.


[1] Mike Young 10:57, 15 May 2007 (UTC)

that is a horrible reference. The chance of coral starving from lack of zooplankton due to overfishing is highly unlikely, esp. for scleractinian hermatypic corals. Most likely high SSTs and climate change will cause greater coral death over a huge range. Corals relies on symbiotic algae to provide 95% of its energy. Zooplankton is very important but the connect between coral--zooplankton and overfishing is extremely weak.

Statement added "Scientists also predict that the Great Barrier Reef can only last for 20 to 30 years. If nothing is done to stop these problems, it will be gone forever.". Was deleted from Coral Bleaching section because there is no evidence of this to my knowledge of a scientists declaring that the GBR can only last 20 to 30 years. In 20 to 30 years the GBR might be algae dominated or single coral species dominated or heavily degraded but no publication cites GBR not existing. --Squahsoc (talk) 10:40, 18 March 2008 (UTC)

Have a look: good 2016 source on GBR and coral bleaching: http://theconversation.com/how-much-coral-has-died-in-the-great-barrier-reefs-worst-bleaching-event-69494 Satu Katja (talk) 16:56, 8 January 2017 (UTC)

Suggestion Talvinlee (talk) 11:31, 6 September 2011 (UTC)[edit]

Shouldn't there be a section on coral bleaching solutions or something that at least says "for solutions see climate change solutions." Something like that.


Suggestion Ariel3 (talk) 20:59, 2 January 2009 (UTC)[edit]

I think the pathogenesis of the disease should be updated. There are many interesting papers dealing with the pathogenic role of V. Shiloi and other Vibrio spp. in coral bleaching pathogenesis, I.E.: Rosenberg, E. and Y. Ben Haim [2002], Microbial Diseases of Corals and Global Warming. Environmental Microbiology 4: 318-326. Sutherland, K.P., J. Porter and C. Torres [2004], Disease and Immunity in Caribbean and Indo-pacific Zooxanthellate Corals. Marine Ecology Progress Series 266: 273-302. I have added some notices only on the known pathogenic role of V. Shiloi. However at least the pathogenic action of 'Vibrio corallilyticus' should be added.

----

new section[edit]

should there be something on effects of coral bleaching?Akid 10:22, 24 August 2007 (UTC)

yeah probably, add coral bleaching effect on reproduction, larave dispersal, coral abundance, coral mortality, fish habitat, tourism etc. . --Squahsoc (talk) 20:57, 18 December 2007 (UTC)

Just a few comments I wanted to make: 1) I noticed the page mentions several times that coral bleaching is mainly due to climate change, but there is no section for it, and there is a section for how sunscreen affects bleaching. Should we add a separate climate change section?

2) There is also no mention of CCA (crustose coralline algae) and how it facilitates coral recruitment. Ex: [2] Should we add this information in?

3) The sections "Cause" and "Trigger" seem more or less the same to me, what do you all think of putting them together? Poli160AA (talk) 04:15, 5 November 2016 (UTC)

Ocean acidification ref[edit]

The given reference for the effects of ocean acidification doesn't seem to me to support the claims made for it. A better one might be this:

http://www.pnas.org/content/105/45/17442.full

What think? —Preceding unsigned comment added by 71.22.217.151 (talk) 06:08, 4 November 2010 (UTC)

But you have given a dead link! --Epipelagic (talk) 09:23, 4 November 2010 (UTC)
ummm... it works for me. There paper is "Ocean acidification causes bleaching and productivity loss in coral reef builders" Anthony et al 2008, PNAS.

http://www.pnas.org/content/105/45/17442 here's a doi. doi: 10.1073/pnas.0804478105 —Preceding unsigned comment added by 71.22.217.151 (talk) 17:51, 4 November 2010 (UTC)

Both references are obsolete and old papers where scientists speculate on what could happen -- they are not scientific studies or valid references, which may be why at least one of them was deleted by the publisher. There appears to be no scientific evidence that "acidification caused by CO2 pollution" is impacting the reefs. Coral produces CO2, would it really be self-destructive in that way?Thoralor (talk) 09:04, 9 August 2016 (UTC)

Potential resource 2.July.2011 Science News[edit]

Mellow corals beat the heat: Species that overreact to distress signals from algae more likely to succumb to warming by Tina Hesman Saey July 2nd, 2011 Science News Vol.180 #1 (p. 12)

Some corals overreact to distress signals sent by resident algae when waters warm, researchers in New Jersey and Israel report online June 2 in the Proceedings of the National Academy of Sciences. The overreactors ramp up production of an executioner protein called caspase and eventually commit cellular suicide. Corals that survive warming start out with high levels of caspase but then quickly decrease the amount of the protein, the researchers found. The study “adds critical data to help figure out how coral bleaching happens,” says Stephen Palumbi, a marine population biologist at Stanford University who was not involved in the research. Corals bleach when their algae become stressed by warming water, pollution or other factors and either leave, die or get eaten. ... In the new study, a type of coral from the Red Sea called Seriatopora hystrix (known as bird’s nest or needle coral) bleached but stayed alive for six weeks in water that was warmed by 6 degrees Celsius, researchers led by Paul Falkowski of Rutgers University and Dan Tchernov of the University of Haifa in Israel found. In contrast, another Red Sea coral called Stylophora pistillata had a meltdown after only a week in the heat. Levels of caspase protein made by the melting coral shot up to six times normal levels, while levels of the protein dropped in the heat-resistant coral.

97.87.29.188 (talk) 22:30, 5 July 2011 (UTC)

Bleached coral photo[edit]

The photograph titled "Moofushi Bleached Corals" is of dead coral on a reef flat and is unrelated to coral bleaching - it looks white/bleached as the sunlight is reflecting off the carbonate substrate. I'll try and upload a more accurate photograph (i.e. one with bleached corals). — Preceding unsigned comment added by Acropora (talkcontribs) 02:59, 8 August 2011

Resource?[edit]

Coral reefs sending a warning signal by Drew Harvell CNN.com September 27, 2010. Editor's note: Drew Harvell is a professor and associate director of the Cornell University Center for a Sustainable Future. Also see related Planetary boundaries. 99.109.124.5 (talk) 06:52, 15 August 2011 (UTC)

Minor edits[edit]

Just starting a series of minor edits intending to clean up a little. I'll document why here:

1. The new residents may be of a different species. - removed, as there is currently no evidence of exogenous acquisition (acquiring new types of zooxanthellae from an outside source that were not previously resident) in scleractinian corals.

2. Removed the bioerosion image. It's slightly misleading: coral bleaching doesn't lead to bioerosion as such, but mortality and tissue loss resulting from bleaching does open up the substrate to increased bioerosion. Either way, the photo as depicted is misleading.

Thanks Tryptofish, let me know if i'm doing anything wrong.

Acropora (talk) 02:31, 22 August 2011 (UTC)

On a quick read, it looks good to me. Thanks! --Tryptofish (talk) 14:40, 22 August 2011 (UTC)

What is the biological effect?[edit]

After the coral expels the zooxanthellae, what happens? Does it die, or might it survive until a later time? Is there some amount of time that they can survive being bleached before running out of energy? I think the biology of this deserves its own section. SSSheridan (talk) 14:14, 24 January 2014 (UTC)

I've started the section using a short bit from the Coral article. I think the biology of the effects on the coral, and on the ecosystem, should be expanded upon. SSSheridan (talk) 14:21, 24 January 2014 (UTC)

POOR QUALITY, not B, and either junk science or missing refs[edit]

This article is not up to any reasonable standards of writing. It conflates coral death (a "90% mortality") with bleaching as if they are one and the same. Where is the description of the proper "health" of a coral, and why the white ones are singled out as being under "stress" (mentioned a dozen times in the article) versus the tendency for this to lead to "death"? The main point of the article is to convince me that bleached corals are indicative of some catastrophic problem in the ocean that leads to the poor health and death of corals.

So I looked at the source for saying that "bleaching" is a "health" issue and leads to "death." I am not impressed. It is a website produced by NOAA with no scientific footnotes and no sources for this. Here is what NOAA says about "mortality" of "bleached corals": (At Reference cited in article, http://coralreef.noaa.gov/aboutcorals/coral101/symbioticalgae/ )

  • Corals begin to starve once they bleach. While some corals are able to feed themselves sufficiently, most corals struggle to survive without their zooxanthellae. If conditions return to normal relatively quickly, corals can regain their zooxanthellae and survive. This stress; however, is likely to cause decreased coral growth and reproduction, and increased susceptibility to disease. Bleached corals often die if the stress persists. Coral reefs suffering severe mortality following bleaching can take many years or decades to recover.

Okay, so "often die if the stress persists"? What does that mean? This all may be true, but there is no research presented that shows how stress and bleaching are leading to significant deaths of corals. Corals die from diseases when they are some other color, so where are the numbers?

I think the actual research papers need to be quoted or shown to correlate bleaching with mortality, or this article needs to be rewritten to say, "Bleached corals are curious and beautiful, but contrary to popular myth, most of them are still alive. Tropical cyclones and the crown-of-thorns starfish combined contribute about 9 times more to coral death than bleaching." Because the NOAA article skips over the details, I think the corals are just using a natural defense mechanism TO STAY ALIVE. And that they can recover their color, get a disease, or die... a lot like other corals. But that is just my impression reading a poorly written article with poor references for its main point. I like to saw logs! (talk) 05:18, 3 July 2015 (UTC)

I think the article is reasonably well balanced, and NOAA is generally accepted as a reliable source. In scientific studies it is much easier to assess the quantity of bleaching rather than whether the coral colonies subsequently die, which requires repeat follow-up visits. As you are so critical of the article, why don't you roll up your sleeves and improve it yourself? Cwmhiraeth (talk) 09:48, 3 July 2015 (UTC)

NOAA isn't claiming that bleaching leads inevitably to death. However when the condition persist, is widespread or the underlying stress persist it is safe the say that the coral is in serious danger. The coral could recover if sea temperatures returned to normal and the pollution was reduced. So it is a safe bet it is only going to get worse. Circuitboardsushi (talk) 19:34, 19 July 2017 (UTC)

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Symbiosis[edit]

The "Causes" section contains two seemingly contrasting statements that could do with reconciling. In the first paragraph we read ...

"... and hence the coral loses the ability to maintain its parasitic control on its zooxanthellae"

Meanwhile, in the second paragraph we read ...

"... and the symbionts will eventually abandon their host"

The first implies symbionts are expulsed (which is how the article lead describes it), while the second implies that the symbionts "jump ship" and head for freedom on the high seas.

My question is: which is it? If the former, one might expect depleted symbionts that struggle to survive outside the coral host. If the latter, one might expect the symbionts to just become a functional part of the plankton again. My understanding of the relationship between corals and their symbionts (which may well be incorrect) was that it was largely a form of captive parasitism rather than a mutual symbiosis. That is, viewed in reproductive terms, corals gain from the association, whereas symbiont reproduction is largely assimilated by the coral and does not, in the long-term, get to serve the reproductive interests of the symbiont.

Can someone set me - and perhaps the article - straight? --PLUMBAGO 09:44, 21 April 2016 (UTC)


Citations[edit]

Just a heads up that there are several citations (such as #8 and #33) that are not the full citation, #37 doesn't work, and #36 takes you to a different page I think. Poli160AA (talk) 04:32, 5 November 2016 (UTC)

Quality of article[edit]

Added Clean-up banner. The issue matters since coral reefs are pretty big centres of marine life worldwide. Following the massive bleaching events in 2016, there is enough understandable online-knowledge that can be referenced. Please chip in! Satu Katja (talk) 12:03, 30 December 2016 (UTC)

Here's a good source: Clear and up-to-date info on Great Barrier Reef coral bleaching. http://theconversation.com/how-much-coral-has-died-in-the-great-barrier-reefs-worst-bleaching-event-69494 The worst bleaching of the worst bleaching event on the Barrier Reef ever, i.e. 2016, occurred in the northern parts of the Barrier Reef. Please, bear in mind: The northern part of the Great Barrier Reef lies off the northern part of Cape York peninsula. There is neither industry, nor sunblock of any run-off or pretty much anything at all that hasn't been around for the last few milleniums. Very few people live north of Port Douglas. It really is jungle. The GBR marine park authority hence blames mostly climate change. (BTW: Hard coral don't live in habitats where the water temp drops below 20 Celsius, so unless there is a change in major currents, there will be no bleaching because of water temp drops since there isn't much coral.) Instead, all coral bleaching events have been preceded by warmer than usual water temperatures.--Satu Katja (talk) 17:13, 8 January 2017 (UTC)
Added UNEP source. Shortened and simplified intro. http://www.unep.org/newscentre/Default.aspx?DocumentID=27092&ArticleID=36336&l=en Satu Katja (talk) 18:19, 11 January 2017 (UTC)
Should the "research paper"- banner be removed? Opinions? --Satu Katja (talk) 18:41, 15 March 2017 (UTC)

On making the article easier to read[edit]

I am considering making improvements to make this article easier to read. I have noticed that there are a lot of scientific jargon and that the Impact, Coral Adaptation, and Coral Damage by Sunscreens segments need to be cleaned up. Also, I see that there are many problems in the Coral damage by sunscreens segment. Should I clean it up, delete it, or move the segment to the triggers segment? I am open to suggestions.Sidneyt512 (talk) 02:37, 29 March 2017 (UTC)

Hi Sidneyt512!

Sounds great! The sunscreen thing: I think there is some controversy around that sunscreen argument since the research was conducted in laboratory settings only. My understanding is that while sunscreen apparently does harm coral, it mostly would be a factor is places with lots of tourists. Hanauma Bay in Hawaii would be such a place. But on the grand scale: No, not a factor deserving a whole segment. I would delete the whole segment and add a sentence somewhere else. http://mashable.com/2015/11/10/sunscreen-killing-coral-reefs/ https://today.ucf.edu/lathering-up-with-sunscreen-may-protect-against-cancer-killing-coral-reefs-worldwide/

Regarding the triggers: IMHO the triggers segment lacks "El Nino", that being the most important trigger. Out of the factors mentioned, some seem major factors, while others … well, not.

  • increased (most commonly due to global warming), or reduced water temperatures - YES. Reduced water temperatures: NO!
  • overfishing - IMHO probably isn't helping
  • increased solar irradiance (photosynthetically active radiation and ultraviolet light)- yes
  • increased sedimentation (due to silt runoff)- only localized.
  • bacterial infections - To my knowledge: No. But bleached coral is "sick" and will succumb to bacterial infections more easily.
  • changes in salinity - To my knowledge that can only be a localized factor. I haven't heard of the salinity of the Pacific and Indian oceans changing.
  • herbicides - To my knowledge that will only be a localized factor. Probably herbicides are not helping any living organism, they are engineered to kill stuff. But there is not a lot of herbicides in the Maldives. Instead, there is lots of warm water.
  • low tide and exposure - To my knowledge that can only be a localized factor. Haven't heard of the sealevels of the Pacific sinking.
  • cyanide fishing - To my knowledge that can only be a localized factor. Cyanide fishing is done some in 3rd world countries. Australia is not known to be one.
  • elevated sea levels due to global warming (Watson)[clarification needed] - No. Probably not. Maybe in some localized way. Some corals grow pretty fast at a rate of 1,5 cm a year. The sea levels would have to rise a lot very fast in order for that to be a major contributing factor.
  • mineral dust from African dust storms caused by drought[21] - localized?!
  • four common sunscreen ingredients that are nonbiodegradable and can wash off of skin- localized?!

Coral needs clean water, just like humans. It doesn't like cyanide, bacterial infections, etc but while those factors all will kill coral, they are only additional factors, not the main culprit. Coral is rather sensitive. (And yes reduced water temperatures would kill it, too. But we're not seeing reduced sea water temps. Coral as rule of thumb needs water temperatures no lower than 20 degrees Celsius and tolerates a maximum of 30 degrees Celsius only for a short time.)

Most people don't know about the symbiosis of the coral polyp and the algae, so they can't understand the whole underlying mechanism of coral bleaching when reading the article as it is now. (BTW So glad you want to do that…)

Here's a nice document with a good intro to coral bleaching: http://www.coralwatch.org/c/document_library/get_file?uuid=9e94823d-66b4-44d8-87b0-7b3de64cca7e&groupId=10136

So glad you picked that article! Satu Katja (talk) 08:37, 29 March 2017 (UTC)

The respectable "Sydney Morning Herald" writes, 16th March 2017: 'Are we there yet?': Fears that 'significant' coral mortality still to come. http://www.smh.com.au/environment/climate-change/are-we-there-yet-fears-that-significant-coral-mortality-still-to-come-20170313-guwq6q.html Satu Katja (talk) 08:49, 1 April 2017 (UTC)
I have been working on a draft in my sandbox page for improvements to the Coral bleaching page and I came across an issue with part of the Triggers section that says that solar irradiance is a trigger for coral bleaching. I am not sure if the source that is cited for that particular section is credible and I need more information. I've been having some trouble finding a good source to use that links solar irradiance to coral bleaching and I feel that I should have a credible source to use so that I can be sure that solar irradiance is a cause of coral bleaching. Can I include solar irradiance as a a trigger? Sidneyt512 (talk) 02:10, 5 April 2017 (UTC)
Hi Sidneyt512! Hm. You're right, I can't find anything that would be current, i.e. written in the last couple of years, either. I'd strike that out, too. (Generally, I lean towards Australian publications. They have the biggest reef system in the world and it is among the best documented - a lot of countries with large coral reefs have none of the things that the Great Barrier Reef Marine Park Authority set up for the GBR. And even in Australia, there is fear that negative press will have a detrimental effect on tourism. So places like the Maldives which heavily rely on tourism for national income have little interest in researching and publicising their reefs going to hell…) Again: Glad you're doing this! Satu Katja (talk) 07:52, 5 April 2017 (UTC)
Hi Sidneyt512! I read your draft in your sandbox. Great! I think the language is great: Easily understandable and to the point. Scientifically, there is a few points I am not sure about, not being a marine biologist: Is there scientific consent on why the coral polyp expels the algae at high water temperatures? If not, I'd suggest simply sticking to the fact that it does expel the algae. I remember reading that the nutrients provided by the algae account for up to 90% of the coral polyps' nutritional needs, and hence chucking out the algae leaves the coral malnourished and prone to dying off. (Also, malnourished coral does not spawn Coral#Reproduction diminishing chances of re-population etc etc.) Satu Katja (talk) 08:19, 11 April 2017 (UTC)
Hello. I got your message. Thanks for your suggestions. The draft that you read was intended to be a rough draft and I am still currently working on it at the moment. I have been looking for more recent sources to ensure that this article remains relevant. I'll see what I can do to improve on it and include appropriate scientific information. Again, thanks for the suggestions and I will be editing my draft soon!Sidneyt512 (talk) 14:53, 11 April 2017 (UTC)
  • Hi! I'm just making a note that Sidneyt512 started working on a sandbox entry at User:Sidneyt512/sandbox that has some content that would be good to use with this article. I'll try to get on this later tonight to see what can be done, but if anyone wants to do this before I do, please feel free! Shalor (Wiki Ed) (talk) 03:34, 11 May 2017 (UTC)
Sounds good! Due to the massive bleaching events of the last years, scientists concur on the reasons of coral bleaching - unlike a few years ago. His draft reflects that change. So, let's… Satu Katja (talk) 06:39, 11 May 2017 (UTC)

New data on bleaching[edit]

Anyone want to amend the data? https://www.theguardian.com/environment/2017/may/29/coral-bleaching-on-great-barrier-reef-worse-than-expected-surveys-show --Satu Katja (talk) 09:24, 29 May 2017 (UTC)

Changed article to C class[edit]

Hi, I changed the article to C class. (Not sure, if I am allowed to do that, please let me know if I don't.) The intro is now okay, but the article does not clarify that the massive coral bleaching taking place right now is not due to sunscreen of any other localized factor, but due to rising sea temperatures.

Regarding the triggers: IMHO the triggers segment lacks "El Nino". Out of the factors mentioned, some are major factors, while others … well, not. The localized factor will affect coral, but remember: eg the Great Barrier Reef spans about 2000 km from north to south. Most of the area is very remote. There is no runoff, herbicides etc etc in the northernmost parts, neither is there cyanide fishing. Same for the Maldives…

Triggers and reasons…

  • increased (most commonly due to global warming), or reduced water temperatures - YES. Reduced water temperatures: NO!
  • overfishing - IMHO probably isn't helping, but NO.
  • increased solar irradiance (photosynthetically active radiation and ultraviolet light)- not sure - yes ?
  • increased sedimentation (due to silt runoff)- only localized.
  • bacterial infections - To my knowledge: No. But bleached coral is "sick" and will succumb to bacterial infections more easily.
  • changes in salinity - To my knowledge that can only be a localized factor. I haven't heard of the salinity of the Pacific and Indian oceans changing.
  • herbicides - To my knowledge that will only be a localized factor. Probably herbicides are not helping any living organism, they are engineered to kill stuff. But there is not a lot of herbicides in the Maldives. Instead, there is lots of warm water.
  • low tide and exposure - To my knowledge that can only be a localized factor. Haven't heard of the sealevels of the Pacific sinking.
  • cyanide fishing - To my knowledge that can only be a localized factor. Cyanide fishing is done some in 3rd world countries. Australia is not known to be one.
  • elevated sea levels due to global warming (Watson)[clarification needed] - No. Probably not. Maybe in some localized way. Some corals grow pretty fast at a rate of 1,5 cm a year. The sea levels would have to rise a lot very fast in order for that to be a major contributing factor.
  • mineral dust from African dust storms caused by drought[21] - localized?!
  • four common sunscreen ingredients that are nonbiodegradable and can wash off of skin- localized?!

Coral needs clean water, just like humans. It doesn't like cyanide, bacterial infections, etc but while those factors all will kill coral, they are only additional factors, not the main culprit. Coral is rather sensitive. (And yes reduced water temperatures would kill it, too. But we're not seeing reduced sea water temps. Coral as rule of thumb needs water temperatures no lower than 20 degrees Celsius and tolerates a maximum of 30 degrees Celsius only for a short time.)

Most people don't know about the symbiosis of the coral polyp and the algae, so they can't understand the whole underlying mechanism of coral bleaching when reading the article as it is now.

Here's a nice document with a good intro to coral bleaching: http://www.coralwatch.org/c/document_library/get_file?uuid=9e94823d-66b4-44d8-87b0-7b3de64cca7e&groupId=10136

Also: Sidneyt512 started working on a sandbox entry at User:Sidneyt512/sandbox that has some content that would be good to use with this article. --Satu Katja (talk) 09:41, 29 May 2017 (UTC)

More references: http://www.smh.com.au/federal-politics/political-news/we-cant-be-passive-bystanders-advisers-call-for-dramatic-rethink-on-great-barrier-reef-20170519-gw8yb7.html http://www.smh.com.au/environment/climate-change/huge-blow-backtoback-bleaching-covers-twothirds-of-the-great-barrier-reef-20170406-gvewah.html Satu Katja (talk) 10:27, 29 May 2017 (UTC)

Deleted section - detailed description of sunscreen as trigger for coral bleaching[edit]

Apparently, that part included original research. Plus: Sunscreen is mentioned in triggers section already.
While sunscreen is likely to cause localized effects, compared to elevated sea water temperatures which have led to coral bleaching on millions of square kilometers of tropical reefs worldwide, the effects of sunblock on selected beaches and reefs frequented by tourists compares to the effects of cyanide fishing: yes, it will cause localized damage, but not wipe out whole reefs systems in the way that elevated water temperatures have done e.g. in Tropical Northern Australia, a large area with no tourism and no sunblock. --Satu Katja (talk) 11:02, 16 July 2017 (UTC)