More Bad News for Caribbean Coral Reefs

[Brogan007]

Originally Posted by jrod321

Dumping chemicals on the reef to cause all the fish to come out really does happen, and my understanding is bleach really is used. It kills everything and is worse than dynamite fishing for the eco-system. It still happens and I'd be willing to bet that bleached reefs in the Caribbean that have been blamed on global warming were in fact caused by this method of fishing.

Sorry, but this is one of those "Urban myths" that gain traction coz nobody explains the real deal. Water temps rise, causing the minute animals (symbiotic zooxantheallae) that live on the coral polyps to die/leave....causing the coral to bleach.
I used to be a Caribbean dive instructor, 10 yrs, & we saw it happen every time the water warmed up significantly. NOTHING to do with bleach.
Now, yes, morons in some areas do use bleach, explosives, spearguns et all....but that another story. The "bleaching events" that one reads of are driven by stress...mainly water temps. Other stress events can have the same result.

[Andrew Troup]

Originally Posted by cfarrar

Just to be clear, I'm not saying that sea temperature doesn't correlate with coral bleaching. In fact, higher sea temperatures probably allow for higher CO2 levels. Maybe someone with more knowledge or a well-written study can clarify this.

Colin

Yes, you're onto something, but you're lumping two separate threats together as if they were the same phenomenon.

Temperature is a problem both directly (causing immediate bleaching as noted by another poster) and indirectly (allowing increased solubility of CO2, decreasing pH, which makes it more difficult for calcium carbonate to be laid down, whether in corals or in seashells.)

This indirect linkage through "acidification", which you allude to, is a serious threat, but separate from damage resulting from bleaching.

Both are sea-surface temperature linked though; one immediately, the other over the longer term.

[Andrew Troup]

Here's a message I recently got from a friend who I thought was a climate change skeptic, who's made a number of sailing trips to Vanuatu over the years

"...we cleared Ambrym and flew in on jib alone to another quiet and peaceful anchorage. Once again we were the only yacht in residence and the place looks pretty quiet. Chief Saitol died in June last year and things may be slipping back a little. The coral also appears to be slipping back as 3 years ago we found what I think was the best patch of coral in Vanuatu but we either missed it yesterday or it has all gone! If it has gone then it is a loss of tragic proportions and you wonder just what is going to happen to the whole ecosystem in the Pacific. I hope I'm wrong!"

I hope so to, but I don't see much solid basis for that hope. It seems to me we need to find a way to get people to distinguish between "I want this to be true" and "I know this to be true".

Even that's not enough though, because then we need to face up to the fact that the things we know to be true make it completely untenable to try to hang on to existing practices and doctrines.

[Andrew Troup]

Just came across this, from an article by John van Tigglen, giving a snippet of the history of the realisation that coral bleaching can arise solely from sea temperature rise:

During his 1928-29 scientific expedition to the Low Isles, off Port Douglas in Australia, (Britain's Sir Maurice) Yonge noticed some of the corals turning white on the reef flat. The days had been hot and calm.
He subsequently found that if he placed a hunk of living coral in water heated to 35°C, it would expel its coloured algae. This observation seemed of little consequence, however, and Yonge did not consider it worth including in his book about the expedition.
Coral bleaching, as a recognised phenomenon, remained pretty much dormant for the next 50 years. It did not occur on the reef, or at least did not capture the attention of scientists again, until 1979.
Bleaching of various reefs was then recorded in five summers over 15 years, which coincided with a sharpening rise in the earth’s temperature. A few scientists sat up, but not many. Certainly reef managers didn’t. It might seem quaint now, but at the time the Great Barrier Reef Marine Park Authority thought it had bigger things to worry about, such as assessing and preventing coral damage from boat anchors and "cyclone divers" (clumsy, inexperienced divers), as well as from starfish, overfishing and fertiliser run-off from cane farms.

It wasn’t until early 1998, when almost the entire reef fronting James Cook University’s marine biology research station on Orpheus Island abruptly turned white, that coral scientists had, as Terry Done puts it, their "Oh f…" moment.
Reefs to the north and south, especially those fringing the coast and islands, had likewise suffered.

Initially, people attributed the bleaching to freshwater run-off in the wake of cyclonic floods. But as the weather got hotter and hotter, the bleaching spread.
Aerial surveys of 650 reefs eventually showed that 270 had bleached, and half of those strongly. By the end of the year, which turned out to be the hottest on record, a sixth of the globe’s coral cover had been affected.

"The scale of damage was overwhelming," recalls Done. "Fortunately, when we went back six months later, we found that most of our reefs were recovering." Done, for one, wasn’t surprised, having seen reefs bounce back time and again from cyclones, from starfish infestations and from being smothered in sediment.
Done was among the first of his colleagues to emphasise the resilience of coral reefs. As he sees it, any healthy reef exists in an ongoing cycle of growth, disturbance and recovery.

Done was monitoring the recovery of reefs bleached in 1998 when, in 2002, hot seas struck again. If anything, this was worse: more than half of all reefs were bleached. But it was the timing, rather than the severity, that shocked Done.
In 2006, reefs bleached again. At this rate, recovery didn’t stand a chance.
If there were a natural cycle, something was giving it an extra whirl.

"I’ve tended to be known as the bloke who says the situation isn’t that bad," says Done. "But I’m finding that harder and harder to do at the moment."

[Andrew Troup]

In a way, (and returning to a point cfarrar made earlier) :

I suppose acidification of the oceans is arguably a bigger threat to coral than bleaching: warming oceans, if nothing else changed (particularly if the warming happens slowly) don't necessarily mean less coral, but could result in coral dying in some areas and thriving in others - others which used to be marginal, because the water was previously too cold.

However dissolved CO2 from the atmosphere is inescapable, if you're a coral reef. You can't just move away from the threat.

Even if the rate of emission does not continue to increase, dissolved CO2 is likely to decrease the pH by nearly 0.5 - the latter figure would imply a doubling of the acidity - by 2100.

It's a double whammy: increased CO2 in the atmosphere causes the ocean to warm further; warmer oceans have a greater tendency to dissolve whatever CO2 there is in the atmosphere. (Conditions which lead to runaway growth, ie exponential rate of increase)

Here, the historical realisation of a potential problem was due to a different source of acidification: Volcanoes.

Researchers found that coral was brittle and crumbled, when it grew in the vicinity of lava which was acidifying the water.

From the same article I quoted above:

"So far, the ocean’s pH, which is traditionally alkaline,
has soured by only 0.1, which of itself is
not enough to dissolve limestone. But the growth
of reefs is relentlessly trimmed by weathering and
grazing fish, and even modest acidification will
slow down growth to tip the balance towards natural
erosion. Wooldridge, a modeller, and Veron,
who has discovered a quarter of Australia’s 400
reef-building coral species, believe if atmospheric
carbon dioxide concentrations continue to rise as
forecast, the world’s corals will be rendered incapable
of net growth in about 50 years. Fifty years

after that, all hard coral species will be extinct."

[GordMay]

Coral reef bleaching is caused by various anthropogenic and natural variations in the reef environment; including sea temperature, solar irradiance, sedimentation, xenobiotics, subaerial exposure, inorganic nutrients, freshwater dilution, and epizootics.

[Andrew Troup]

Thanks for that comprehensive list, Gord.

A fair amount of scientific opinion seems to support the notion that, in the Caribbean, the proximate cause of much of the bleaching to date has been direct contact with seaweed (leaching lipid-soluble compounds harmful to corals).

The cause of the rise in seaweed is less clearcut. Some point at overfishing (or other attrition) of herbivore species, but nutrient availability is also clearly a factor, as it is for algae generally.

It also seems to be fairly widely agreed that so far (in modern times), acidification has been a minor contributor in comparison with temperature. That makes sense: the thermal inertia of the oceans is considerable, in comparison with that of the atmosphere, and CO2 dissolution is a bulk phenomenon rather than a highly localised one. That seems likely to change, because acidification is so inexorable and inescapable, as I mentioned earlier.

Here's another interesting snippet from the same article, linking past acidification of the oceans with coral survival:

( I haven't had time to do a comprehensive search on this topic.
I was skeptical, after finding this:
"One-third of all (coral) families and over 70% of all (coral) genera became completely extinct at or near the end-Cretaceous boundary."
Which suggests the claim below might be overstated.

On the other hand,

Ken Caldeira, in a lecture on March 5, 2007, at the Smithsonian National Museum of Natural History in Washington, D.C., told almost exactly the same story I quote here) :

Sixty-five million
years ago, at the end of the Cretaceous Era, a
comet smacked into Mexico’s Yucatán peninsula
to unleash the apocalyptic dust cloud that spelled
the extinction of dinosaurs. Less famously, the
date also marks the disappearance of coral reefs
from the fossil record for some two million years,
because the released minerals produced so much
acid rain that the limestone laid down by corals
and shellfish dissolved. (Hence the end of the

Cretaceous – the era of chalk.)

[Mr B]

Its interesting that a lot of these coral bleaching incidents and dates also happened in the middle of Australia's severe drought periods,

Approximately we have a severe drought every 9 years or so, Then floods, for a few years and then back to drought for a few years,

Droughts means very Hot and bushfires, 40 + Celcius, across Australia,

Floods, means just that, Floods very extreme,

Our last 13 year drought finished in 2010,

2002 2006 was in the middle of this severe drought,

Victoria built a desalination plant to overcome this severe drought situation, as the dams were running empty,
It has not been used as the drought has been broken and the dams are full again,

Approximately 2020, give or take a few years, The drought will be on us again, and the cycle will start again,

The worlds weather is not calculated by a computer, or runs to set dates, It is totally unpredictable, it does what it does, when it wants too,

Average out the worlds weather over the last 1000 years, you might get an accurate picture of it,
Over the last 20 years or so, Dont be rediculous, 13 years of it was drought,

[Andrew Troup]

I'm not going to respond to post #53 because I can't make any sense of it.

For instance, the third-to-last sentence comprehensibly (sorry, that's a typo, as well as being a flat lie; I meant comprehensively) contradicts the second-to last sentence.

[Miniyot]

Originally Posted by Mr B

The worlds weather is not calculated by a computer, or runs to set dates, It is totally unpredictable, it does what it does, when it wants too,.....

....Average out the worlds weather over the last 1000 years, you might get an accurate picture of it,
,

Originally Posted by Andrew Troup

I'm not going to respond to post #53 because I can't make any sense of it.

For instance, the third-to-last sentence comprehensibly (sorry, that's a typo, as well as being a flat lie; I meant comprehensively) contradicts the second-to last sentence.

Dude...first you say you will not respond to someone, then you quote him and (it seems to me) you call him a liar.
I am sure I saved the previous sentences you referred to, Please correct me if I am mistaken.

[gts1544]

Posters, This may be a little off the theme of this thread, but please bear with me. I feel very strongly that extreme positions of any stripe are apt to go down to defeat and probably should. I am a firm believer in the 80 / 20 Rule which basically states that you can achieve 80% of any goal with the expenditure of 20% of the time, effort and money that would be required to get to 100%. The obvious inference is that attempting to close that 20% gap will require the remaining 80% of time, effort and money and is most surely not worth it by any objective analysis. If you stop to consider what could be accomplished worldwide by achieving 80% of our goals at very reasonable cost and using the savings wasted in trying to accomplish the last 20% to initiate many more 80% projects that most could support. Let's all make an effort to come off of some of our extreme positions and make the world a much better place! EPA, are you listening??

[Andrew Troup]

Originally Posted by Miniyot

Dude...first you say you will not respond to someone, then you quote him and (it seems to me) you call him a liar.
I am sure I saved the previous sentences you referred to, Please correct me if I am mistaken.

You did misunderstand me. I'm sorry my meaning was unclear.

Firstly, I took Mr B's "sentences" as being separated by a blank line, because he apparently doesn't see any merit in full stops (you may know them as 'periods').

So the two sentences I was referring to were

<<Approximately 2020, give or take a few years, The drought will be on us again, and the cycle will start again,

The worlds weather is not calculated by a computer, or runs to set dates, It is totally unpredictable, it does what it does, when it wants too, >>



I was saying I didn't know how to respond to his post because his message swings, in the space of one sentence, through 180 degrees.

The first sentence quoted is the summary of his claim that the weather runs in cycles, so that he can authoritatively predict drought (and presumably coral bleaching) in his part of the world in about seven years.

The second sentence quoted claims that the weather is totally unpredictable and runs to no timetable.

It was not a case of me responding to his post, when I pointed this out.

It was me explaining why I can't respond -- for instance, agree or disagree -- because I don't understand any of the ideas in it.

Even taking the two main ideas separately, I don't understand how either one relates to the topic of the thread.


The part you interpreted as me calling him a liar was in fact me commenting on my own (actual) typo:

I intended to describe his two key ideas as "comprehensively" contradicting each other, but my fingers came up with "comprehensibly" ...

In view of what I'm pointing out here, I reckon this was an outright lie on my part.

But the typo struck me as mildly ironic and a joke against myself, so I left it in.

[Mr B]

If you lived in Australia you would understand it,

Our weird and wacky weather patterns are Boom or Bust,

We go from one extreme to the other, Droughts or Floods,

Explain the bottom piccys, The photographer said they went for about 40 minutes,

On a clear day with blue sky and no wind, It was in the out back of Australia,

[Andrew Troup]

<<Mr B has just replied to a thread you have subscribed to titled - More Bad News for Caribbean Coral Reefs

Here is the message that has just been posted:
***************
If you lived in Australia and understood our weird and wacky weather cycles you would understand it,
We go from one extreme to the other, Floods to droughts, Boom or Bust,

The inference was, You cant predict or even get some idea on the worlds weather by looking at the last 25 years, Which a lot of people try to do,

Explain the picture below, No wind and a clear blue sky. The bloke that took the Piccy said it went for about 40 minutes,

It was taken by a Photographer in the outback of Australia,>>

***************



I agree with the underlined statement

[Therapy]

Originally Posted by Mr B

If you lived in Australia you would understand it,

Our weird and wacky weather patterns are Boom or Bust,

We go from one extreme to the other, Droughts or Floods,

Explain the bottom piccys, The photographer said they went for about 40 minutes,

On a clear day with blue sky and no wind, It was in the out back of Australia,

I have never, ever seen nor heard of anything like that.

Untill verified I call Photo Shop.