Caribbean reefs, anthropogenic destruction, and your thoughts

[galleon]

(Just for you, Jerel )
To what extent do you think non-natural (ie, non-"cyclical") Caribbean/Tropical West Atlantic reef degradation occurs, and how much of it is anthropogenic? What stock do you take in which of the current "theories"?

[Spanky]

Originally posted by galleon:
how much of it is anthropogenic?

Some but not enough to matter.

What stock do you take in which of the current "theories"?

Saharan Dust, bet all your money on it.

Would this be considered insider trading?

Jerel

[galleon]

Saharan dust (and associated fungi and bacterial cyst pathogens )....
Jerel, you already know my money has been on that for a long time. I think the evidence has leaves a lot less to be desired than the tourist/pollution/etc. theories. It starts...Through use of iron markers, soil portions on Caribbean islands are found to be African derived. Satellite photos show massive dust clouds coming off of the desertifying and drought ridden African continent, ending their flight in the Tropical West Atlantic. Aspergillis, a fungus that can only complete its reproductive life cycle on land in fine soil, infects gorgonians throughout the Caribbean. How is it spreading if it can't complete its life cycle? Easy. More of it keeps coming over in its pathogen state from Africa and becoming water-borne in the Caribbean. Bacterial cysts in the sand also can become potential pathogens. The list of evidence keeps getting longer...

[ 06-30-2001: Message edited by: galleon ]

[Spanky]

You're really baiting me, aren't you? You know I could go on and on, don't you? How much band width does this thing have anyway? Considering that you're quoting me anyway??

[ 06-30-2001: Message edited by: landescaper ]

[Alice]

All right, I'll play Anthropogenic sources of destruction from tourists, land-based pollution (run-off, sewage, clearing of land..especially for those tourist traps <g> ) have contributed to the decline in reefs, although I'm sure deforestation has been more of a major contributor elsewhere. Any numbers on how much decline was caused by all these former anthropgenic sources vs. Sarahan Dust? What state of decline was the area in before the Dust and Aspergiillis hit? Has the Sarahan Dust affected the SPS population, which was already in decline, as well?

I'm getting a glimpse into how tough research in this area can be as well as how *divided* the researchers can be and it's a little scary. It would be a shame to see the reefs die while the cause was being argued in committee, as it were.

~Alice

[ 07-01-2001: Message edited by: Alice ]

[Spanky]

Alice,
Good Morning Sunshine!
I still haven't had my update on the new tank!! with pictures!!

Ok, while no one can deny the localized effects of development/population, it does not explain why all TWA reefs are effected and the time line. We have shown beyond any doubt that this is/was a naturally occurring event. Tied into the wet/dry cycles that have been occurring before population. Iron markers were the giveaway. I really can't elaborate any further right now.

Eugene Shinn worked out of a facility in Key Largo in the '60s and published several papers here. Some stated the obvious (you needed a $65,000 grant to tell me that?) and some were ground breaking in the sense that he was well respected and if he said it, it must be true. One of Eugene's best observations was his growth studies of Caribbean reefs. He showed how reefs are dependent on what we would consider massive damage in order to survive. How boulder types would be overgrown by branching types if it weren't for storms and how the branches that die provide substrate for new reef.
If I might also paraphrase Jim Tilmant in Biscayne National Park, incidental damage to branching corals by diver contact is undetectable compared to other natural stresses. Even at the most heavily used dive sites, one storm can produce far more damage that hordes of divers. Boulder corals are essentially impervious to incidental diver damage. Deliberate experiments where surfaces of brain corals were damaged showed extremely rapid healing.

Anywho, this is all I can say right now without tipping my hand. I'm sure my old friend Chris - who found me over here will have much to say about this as soon as he gets a pot of coffee in him. He can elaborate on this without fear of repercussion.

Jerel

[Alice]

Thanks, Jerel. And Welcome, Chris!

Ok, so my motor's running, lol. I know that storms take their toll on the reef but that fragmentation is not only a way to provide a substrate for the reef matrix, mini-ecosystems for countless critters, it also provides for asexual reproduction of many of the branching types of stoney corals. Are all the TWA reefs classified as give-up reefs? (Growth is not able to keep up with destruction) I'm assuming that all anthropogenic factors are contributing to this in some fashion but the Saharan Dust is the leading factor. How much is the Dust contributing to the turbidity of the water around the reefs? Are you seeing a major take-over of algae? Are any corals showing dominance due to the die-off of gorgonians and the reduction in schleractinians?

Is Aspergillis in anyway species specific or is it affecting the gorgonian population in general?

I'll shut up now <bg>

~Alice

[ 07-01-2001: Message edited by: Alice ]

[galleon]

Alice, good morning, and let me commend you on what a wonderful board you have here...

OK, this dust is basically, well, bad. Dr. Alina Szmant did intensive studying of nutrient (pollution) paths from their inshore source out into the reef channel in the Florida Keys...funny thing is, the concentrations of the pollutents by the time they had reach several of the reefs she was tracking, were as low or lower than the concentrations of pristine reefs elsewhere in the Caribbean. The data show a definite, sharp gradient in concentrations...over seagrass beds. Yep, she had found that young seagrass beds of Thallasia and Zostera had been expanding to fill sandy areas where turbidity still allowed them to photosynthetically saturate. The seagrass populations had been expanding to compensate for the input of nutrients. As a result, the amount of nutrients that were being pulled over the reef before the development were the same now as they had been prior to development. What is a possibility, is that before the seagrasses began to demographically compensate for the outgoing nutrients, enough pollutants reached the reef to cause a decline, and once the seagrass created that buffer, they were allowed to recover. Many, including myself, are skeptical of these views do to common sense. The grasses would continue to spread slowly sucking more and more nutrients up in a gradient, as the pollution didn't become massive overnight. This demonstrates yet another case of nature being smarter than man gives her credit for.

OK, now pollution is a not a major factor...but ever since the late sixties, these reefs have been declining.... algae is overtaking and fungal diseases are reigning. Well, lets try a different theory then, shall we? Tourists. Surely the tourists are what is providing the stress that is making the corals physically susceptible to these diseases, right? Not exactly. As Jerel noted, it has been genuinely shown diver contact hardly affects a corals resistance. Their is no major link between overgrowth, destruction and contact by humans or diver traffic in general. The corals most frequently "damaged" by divers are Colpophyllia, Diploria, Acropora and Montastrea, yet all manage to recover in a matter of days to weeks, with the only increase in potential pathogens is actually coral-associated bacterial populations that rise systematically to consume dead tissue and the copious amounts of extra mucus being produced. I've seen these corals recover myself, it is remarkable. Also, as Jerel already pointed out, years of high diver traffic does little compared to a single tropical storm or hurricane or winter spell (I'm hesitant to include that one, because its effects are highly variable, and at this point, poorly quantified). So ok, sure there have been recent hurricanes, and doubtless, they have most certainly caused damage. However, this damage is cyclical, and what is affected has been destroyed and repaired for millenia. We can watch it (even without the "nurseries" of those pesky reef-reliefers ...oops, was that out loud?) recover before our eyes, gorgonians first, then (of the major hermatypics) Acropora cervicornis and the other thinly branched species, then lettuce and encrusting morphologies like Agaricites, and the Madracis species. Next usually comes the beasts; Acropora palmata (actually a very fast grower, it just requires longer to "recover", because it must gain ample encrustation to anchor it against the massive "Bernoulli effect" its branches have.), then come the brains (Diploria, Colpophyllia), and then, finally the star corals (Montastreas)

That still doesn't explain the chronic die-off and over growth people think are irreversible and 100% anthropogenic. Lets tackle the algae first. Since the 60's, that African dust has been coming here and settling. Well, this desertification and drought in Africa matches the algae and disease timeline perfectly, and explains the huge scale. The dust is iron-fortified (an understatement). Guess what, iron is an algae fertilizer. Even zooxanthellae mitotic index goes through the roof when iron is present. Iron-rich laterite clay is often used to grow seagrass and algae. Julian Sprung could probably tell you all about it, he's been using the stuff for a long time as substrate in seagrass systems. Next, lets tackle disease. As already mentioned above, Aspergillis sydowii and similar fungal and bacterial diseases that have been isolated in corals that are dying off on an oceanic scale (Caribbean, Tropical West Atlantic, even on isolated islands, almost free of human interference), come from the iron rich soil and dust. None of them can even reproduce in the water. It was also a very "dusty" time period for the African winds when the Diadema died off. At the moment, Eugene Shinn and company are analyzing new and old coral cores for dust that coordinates with past declines in the reefs (they are noted, extensive studies have been conducted on "reefs before Columbus"). I think last year microbiologists were examing dust samples from the Virgin Islands. Their results may be in print. I mean, think about it. We have no other explanation for stuff like black band, white band, etc. disease other than speculating about the 2 billion tons (and the volume fluctuates greatly, but has increased in the past 25-30 years) of dust that now makes its way to the Caribbean annually.
Cheers,
Chris


(dust being blown off the African continent via onshore storms, February 26, 2000)

[ 07-02-2001: Message edited by: galleon ]

[Doug1]

Thanks to MACO I was actually able to follow that

[Alice]

Thanks Chris; I was editing my little welcome post into a longer one and when I posted it, I'd found you'd already answered most of my questions Are the urchins making any kind of comeback at all? It seems as if they could, it would help to keep the algae in check and at least give the reef the chance to recover in it's own fashion.

[FishDaddy]

Me too, Doug, even though I'm a laggard in my MACO studies!
The Sahara theory (with documented evidence) is consistent with reading that I've done over the past couple of years. Man's capacity to influence/pollute the earth has increased significantly with world-wide population booms but Mother Nature has dealt some very traumatic blows to the earth in the past. Fossil records show several events before man's appearance on the scene that virtually destroyed existing coral reefs only to be regenerated, though sometimes by different species.
I do believe the impact of the Sahara sands are compounded by the ocean warming; effect of man; and depletion of the ozone layer.
I dived Rum Key in the 70's and the coral was gorgeous; Bimini in the 70's and 80's and I saw some decline; Key Largo in 1991 and there were acres of dead Staghorn!!! I wasn't a reefer back then so I didn't understand much about it but the differences were striking.
In the late 80's and into the 90's, it seemed popular to attribute the decline in the Florida reefs to agricultural runoff; sewage; and other effects of the population growth in Florida.
No one ever mentioned it but the widespread use of SunScreen by tourists dipping into the ocean beaches of Florida could be a factor! Thousands of gallons of Coppertone and BullFrog lotions couldn't possibly help sea life! (I know, I know, its far out but everything should be considered! )
Excellent thread!
Dick

[FishDaddy]

Jerel,
I saw several of those brain corals in small patches in the weed beds in the shallows off Fort Jefferson while snorkeling in the Dry Tortugas last week! They were scattered, along with a few gorgonians and sea fans, but were a surprise to find them in 1-3' of water off the beach.
Dick

[Spanky]

Dick,
Yeah, you never call you never write!

You didn't touch anything with a green tag on it, did you?

Take a look, these are the guys that can take the shallow water. >
http://www.usol.com/~islandbuck/Rock...s/crop0035.jpg

[FishDaddy]

Jerel,
Nope, didn't see any gree tags.
The one in the picture above is what I saw in the shallows....the channels were exactly the same. I saw at least a dozen widely scattered about, growing right on the sand.
We were on a sailboat out of Punta Gorda; spent two nights at the Tortugas; didn't get to go to Loggerhead Key where the reefs are as the &%^$**&@ motor on the dinghy wouldn't start!
I promise to call next time I'm down ...my grown daughter lives in Sebastian so we're down there couple times a year.
Dick

[ 07-01-2001: Message edited by: FishDaddy ]

[galleon]

Long spines have come back in all areas.

So I hear.

Only time will tell.

Amen to that.

re: G. ventalina, Jerel is right, I was referring to the population overall, but based on distribution, there are pockets untouched. This could be for any number of reasons; low pressure storms that hit at the right place in the right time, a certain anomaly in the currents based on their geographic location, etc. We just can't know all at once. It really is overwhelming, the amount of data that needs to be collected. There is overall recovery, as it is either a low dust period right now, because, the fungus only infects and dies, it can't reproduce, it only spreads or retains populations inter-colonially through continual reintroduction via the dust, or an adaptation is becoming apparent. My vote goes to the latter, as I don't think the dust situation is improving.

Don't you just love Chris on coffee? Aren't you glad he found me over here?

I just can't take a hint, can I?

There is a very good chance that the surviving members have developed a immunity/resistance.

Good point. They either do this, or go extinct. 99% of all species that ever lived are now extinct, but this likely because you have to have survivors in the first place to develop this resistance, which isn't always the case.
Cheers,
Chris

[ 07-02-2001: Message edited by: galleon ]