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Global Warming politics aside as easily as a catastrophe can be pushed aside.

Is anyone more informed able to explain how the KT Extinction event affected corals?

How were they able to survive the mass extinction event of the dinosaurs if they're so sensitive to temperature changes?




Googling "coral kt extinction" gave me this BBC article- https://www.bbc.com/news/science-environment-45133197

So it looks like either corals evolved after the KT extinction event or they survived in very small amounts (maybe a few species) before re-exploding in diversity after the extinction event. This can be seen in global warming today- some corals take to the hotter water better than other corals, and even some regions that have had hotter water historically have corals that aren't really affected, while the Great Barrier Reef and similar are undergoing a mass dying.

EDIT: Also, deep water corals do exist, so it's possible they survived from there. https://en.wikipedia.org/wiki/Deep-water_coral


Thank you for you response.

I should have LBYL instead of EAFP


I hate acronyms so much.

LBYL - Look Before You Leap

EAFP - Easier to Ask Forgiveness than Permission


Thank you very much


You must have really hated the early internet then!


I am no expert but I had been diving with with some marine biologists. They were pretty sure that corals are able to adapt - move to cooler waters with right light / temperature combination.

The problem is that coral reefs grow slowly so if existing reefs die it would be loss for us divers and for the entire ecosystem (fishes etc.) that's irreversible over say 100 years perspective.


Nevermind 65 million years ago, corals survived 400 ft of comparatively rapid sea level rise at the end of the last glacial period 11000 years ago. All the existing reefs drowned. They're hardier than we give them credit for.

They're in trouble again thanks to us, but now they also have us to help. We can plant reefs and engineer heat resistant breeds of coral.


Corals live underwater...


Corals don't live at those depths, not "regular" corals anyway. They need to be close enough to the surface for the sunlight to feed the symbiotic organisms on which they depend.


They need to be close to the surface to get enough sunlight to live.


Survivor bias. Many species went extinct, hence the name of the event.

We should treat mass-near-extinctions that are going on very seriously, if we want to have a diversity of life and not brown toxic goo everywhere.

Yes, humans are unlikely to go extinct, since we know vertical farming and airponics, but all the beauty of life around us can disappear.


They are not that sensitive to temperature change, the article is bad science, the reefs are being bleached and killed by titanium and zinc much of which comes from sun screen. That is why the only reefs that are surviving are in remote areas that do not see the population density to elevate the water to the ppm that its needed to bleach the coral, I live less than 3 miles from Mote marine and run into and talk to many of their researchers not one of them has ever told me that they have data that warming alone is bleaching the reefs but they know for a fact titanium and zinc are, they are one of the foremost research centers on reef science and reef restoration:

https://www.icriforum.org/sites/default/files/ICRI_Sunscreen...

https://time.com/4080985/sunscreen-coral-reefs/

IIRC Hawaii has already banned sunscreens that contain those products and we have banned it in the Florida Keys. It is what is causing bleaching, we know it for a fact. My daughter while not a marine biologist yet, is well on her way, she does a lot of work on reef restoration and focuses her studies on Coral as it is what she wants to do. The entire focus on reef restoration is in the areas of agricultural run off, micro-plastics and suspended micro metals elimination as well as reforesting. Ocean temperatures are not killing the reefs if it was it would be as simple as troughing deep water and using tidal flow to up flow cooler water over the reef. I actually had this conversation with one of the researches once, as I interact with them from time to time due to my daughters interests.

Coastal mainland Florida has lost all of it's reefs, they where alive when I was a kid but where dying. It was also the time when Florida saw a huge tourism and population boom. The reefs in the keys where fine at that time, but by the early 90's the lower keys from the 7 mile bridge to Key west started to see signs of bleaching, meanwhile there was no evidence of it in the upper Keys which sits right in between the dead reefs of mainland Florida and the dying reefs of Key West. The difference was Key West became a larger tourist destination in that time due to the formation of the tourist development council in the years preceding. For the most part Key Largo still does not have the same problem (it is happening though, due to agricultural run off) because it sees less tourism than Key West and the tourism it does see is more SCUBA based tourism who generally do not wear sunscreen.

Another culprit is agricultural run off, while I am not a fan of the article below because it states it's global warming out of the gate, then offers no fact to back up said statement and omits the fact that the study they cite noted in the study that there where no increases in average water temperature in the Keys during the study, or the fact that the Keys has seen a Keys wide drop in average water temps for the past decade. There where several spikes in temperature above the threshold and die off where only observed when massive runoffs where in place. When the temps exceeded the threshold and runoff nitrogen and phosphorus where observed to be in low PPM there where no recorded die-offs. That being said it does do a good job of explaining what said runoff is doing to the reefs. Basically when the water hits a certain N:P ration in the presence of of warmer water, it kills the reef. Without the N:P ration the reefs thrive in the warmer spikes so, water temp is second to the fact that the presence of agricultural run off creates the chemical environment that is toxic to the reef. The heat is only the catalyst when those chemicals are presence.

https://www.hwhfoundation.org/news/nutrient-runoff-starves-c...

https://www.npr.org/2019/07/16/742050975/floridas-corals-are...

In the Keys we have banned fertilizers for lawn maintenance and we have moved the population centers to sewage whereas just a decade ago every house outside of Key West and Marathon has septic systems. But we still have a huge issue with Big sugar dumping water into the everglades which runs out of the gulf and over our reefs.

I am very concerned about our reefs and it is important that people know exactly what is killing them. Fixing global warming is not going to save our reefs. It gives people a false sense of security and needs to be rebuked as bad science.


The first article you cite says:

"The chemical UV filter oxybenzone has been studied most intensively and the following effects have been described: Bleaching of coral fragments and coral cells from various species of hard coral. This effect is more pronounced at higher water temperatures."

Sounds like, as with many things, the story isn't simple. Multiple environmental changes simultaneously can have consequences where each, by itself, would have much less effect. In general, we need to tackle all the causes to some degree to have much hope of success.


It is fairly simple, they do not die in the same temps when the PPM of these chemicals are low, the temps are secondary and are allowing the chemicals to make certain bonds that are toxic to the reef. Absent the chemicals the reefs tolerate the temperatures just fine. They are only sensitive to temperature when the chemicals are present thus the chemicals are the primary source of death and thus their elimination is paramount to the survival of reefs. The chemical are what kill the coral not the temperature as if you heated the water to threshold, then cooled it, then poured it on coral it will kill it as the water has reached threshold, thus the bonds have been made. This study was actually done here in the keys, I will see if I can find the paper.

Both agricultural run off and sunscreen follow a similar pattern.


No marine scientist with any credibility is suggesting that sunscreen or plastics are a larger threat to coral reefs than climate change. The articles you yourself are citing from ICRI call out that studies on sunscreen are ex-situ and do not reflect what occurs in nature. Agricultural runoff makes the impacts of climate change worse but the main drivers of bleaching are temperature and ocean acidification.


I provided many references, and have talked to many of them. I live in the heart of US based coral research Mote being literally on my Island and Harbor Branch being where I grew up, as I said my daughter is well on her way in this field. While I many not be a certified expert, I have a bit of arm chair knowledge in this field. I mean I literally drink at the Sugarloaf Tiki Lodge with a few of them and help my daughter understand the chemistry in the papers she has to understand. A few links to your sources would be nice in a refute of what I have provided. Because I know quite a few credible marine scientist that say runoff and micro metal / plastic is what we need to focus on. I was literally at the meeting with them when we convinced Monroe county to ban traditional sunscreen and the science was solid that is why we banned them and it is why Hawaii banned them (to put it into perspective, I was hanging out with the Tim Berner Lee's and the brendan Eich's of coral research, trying to accomplish a goal). I am not trying to be a douchy name dropper here, but I think it is important in trying to highlight how substandard of a refute and insulting you refute is to a well thought out post that I took time to gather links and articulate is.

We don't just get to say global warming blah, blah like a vampire and everyone runs scared. Its really starting to aggravate me that AGW has permeated doomsday science so much that we just invoke it when we need magic. It has become a god and certainly has become a god of HN environmental posts. I provided links and a well thought out post and you get to refute me with nu-uh AGW! I mean AGW is to the environment what CBD is to what ails you. I mean I have been thinking about picking up some CBD to put on my head to stop my male patter baldness because it cures so much stuff. I say that as a dyed in the wool tree hugging hippy, that actually knows via research that AGW is a real thing. But have been alive long enough to know that people exploit literally everything for their gain and AGW is no different. This thread is a perfect example we know, no if ands or buts what is killing the reefs but some how we have to work AGW in there or it's not a fact. When in fact it is a fact and it needs to be accepted fact because there is solid science behind it, because when they go it will finally give all the doomsday environmentalist what they are looking for, because the rest of the ocean will go with it. Junk science needs to be refuted at all costs, it hurts science more than it helps it. Water temperature rise killing the reefs is junk science. It is a catalyst in the presence of the real poisons.

I mean no disrespect, and am certainly not trying to be a jerk, I value all opinions, but I am very passionate about this subject and do know the facts on it. Look at my history I rail on and on about how ocean pollution is a huge danger to us, that being said, you need to provide these scientist that claim AGW is the source of reef bleaching. Because I can certainly get Dr. Michael P. Crosby to come on here and do an AMA. Your response comes off as a refute by appealing to the populous crowd, devoid of any fact. Again I am not trying to disparage or disrespect, but there was no refute in it other than what amounts to nu-uh.

Some areas of corollary data that you need to refute if you want to support you position are:

Why are the Bikini atolls, which got nuked less than 100 years ago, flourishing, when they are shallow and have seen average temperature rise above other areas that are dyeing. Yet they have very little tourism and no agricultural development?

http://www.nbcnews.com/id/24132798/ns/world_news-world_envir...

Why are remote areas on the Caribbean such as Tortuga not seeing the same die off, even though they are in the same thermocline as the rest of the keys and have seen the same temperature gradients as the keys.

Why has Cuba not seen the level of reef bleaching that the more industrialized Florida has seen, even though it has higher average water temperatures?

https://www.sciencenewsforstudents.org/article/exploring-mys...

Why does Bimini and other parts of the Bahamas still retain living reefs in less than 15 foot of water even though shallow water reefs have on average higher water temps than Florida or the Keys whose reefs tend to exist in 20ft or below.

and also to note, there have been die-offs when threshold temperatures have not been reached, when additional chemicals a present that act as a different but complementary catalyst in the absence of tempature:

https://oceanservice.noaa.gov/news/weeklynews/mar10/cwcoral....

Until you can solidly refute via science, all of those you don't get to invoke global warming as a fact for reef die off and you certainly don't get to appeal to authority of "any marine scientist with any credibility". All of those are converse facts to what you claim but are not to the facts that I have presented.

Again I will say it simply and clearly we are pumping poisons into the ocean, temperatures can make them more poisonous but in the absence of the poison, temperature alone causes no die off. It certain circumstances, in the presence of other chemicals temperature is not even required for die-off. These are all verifiable facts.

It has never been observed that temperature (within normal earth water temperatures) alone kills coral. This is also a fact.


Some species of coral are resistant to temperature, others are not. Generally, the most visually spectacular coral are the most sensitive to temperature.




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