BVI Coral - Where'd it Go ?

[bstreep]

We've been going to the islands for 30 years. I've always remembered seeing places with vast stretches of dead corals - it's part of the process. Living corals actually grow rather quickly. In captivity, they can grow 1-2" per MONTH. As they build reefs, there comes a time when their building cuts off currents that bring cool water and nutrients to them - and they die off. That reef eventually becomes land.

They are also very resilient. They reproduce both sexually, and asexually (pieces break off). Like many marine species, they produce thousands and thousands of "babies", almost all of which don't survive. Only those that find their way into a favorable environment, live and grow.

Also remember: coral bleaching is NOT coral death. Corals bleach when they expel their zooanthellae. It's a stress mechanism. Sometimes they die, most of the time they recover. It's been going on for a LONG time.

[Scottie2]

Originally Posted by bstreep

Living corals actually grow rather quickly. In captivity, they can grow 1-2" per MONTH. As they build reefs, there comes a time when their building cuts off currents that bring cool water and nutrients to them - and they die off.

Thanks bstreep. Can you quote a reference? Any growth rates I've seen were in millimeters per year

I wouldn't say that the areas I witnessed could have died from being "too built up" It has to be something else

[bstreep]

Originally Posted by Scottie2

Thanks bstreep. Can you quote a reference? Any growth rates I've seen were in millimeters per year

Sure. As I said, "in captivity". So, that would be my living room:

reefin streep style - MAAST Forums

Also, the reef aquarium industry has become more and more oriented towards mariculture (in lagoons in the islands) and aquaculture. Collection and importation of corals is so protected now (that's good) that many parts of the hobby have become completely sustainable. It also provides employment for islanders in the business.

I do recall that Hurricane Omar went thru the BVI last October (2008).

[Bash]

scientific literature is just beginning to explore the phenomena of mass coral bleaching episodes. a recent, concise article from researchers at the University of the Virgin Islands can be found at www.uvi.edu/sites/uvi/Documents/Research%20and%20Public%20Service/CMES/uvi_cmes_bleaching_disease_feb09.pdf

[RetiredSailor]

Originally Posted by bstreep

I do recall that Hurricane Omar went thru the BVI last October (2008).

Actually, it was a near miss, going just southeast of the BVIs, closer to a line between St Croix and St Martin. There were gusts in the BVIs but nothing that would impact coral.

Good point about bleaching not necessarily leading to coral death. In many cases it has, though. I suppose it has to do with how long the conditions last that cause the bleaching.

[GordMay]

Recommendations for Coral Reef Conservation
to the Obama Administration and the 111th Congress

(Signed by forty-four coral reef conservation groups and stakeholders, and one hundred and seventeen marine scientists and professionals)

A coalition of conservation organizations and marine scientists recently (July 2/09) called on the White House and U.S. Congress to protect corals.
Coral reefs are in decline around the world. A report issued last month states that the overall live coral cover for reefs in the Florida Keys has diminished by 50 to 80 percent in the past ten years. Many factors have influenced the decline of coral reefs, including climate change, overfishing, nutrient pollution, vessel impacts, invasive species, and disease. Scientists say that 20 percent of the world's coral reefs have already been destroyed, and another 24 percent may be lost within our lifetime if human impacts on corals are not reduced.

Goto ➥ Recommendations for Coral Reef Conservation to the Obama Administration and the 111th Congress | Coral Reef Alliance

Or ➥ http://www.coral.org/files/pdf/White_Paper.pdf

More News about Coral & Reefs:
➥ http://www.coral.org/news/headlines

[nautical62]

Next time you are there check out Tetor Bay, in the northern part of Savannah Bay. Much better than the Indians. The reef at the south tip off Sandy Spit is pretty good too. If you like Caves, check out the point just north of Lee Bay on Great Camanoe. It's much better than "The Caves"

One thing I've learned about both the guidebook and charter briefings is they steer you to the places that are easy, sheltered and have day moorings. These are not necessarily the places that have the most spectacular snorkeling.

[Alexei]

Last summer I saw a documentary series about a number of natural changes that have been occurring......I forget the title, but they got Edward Norton to be the host/narrator.

One of the episodes centered on the Caribbean coral issue, and followed around this marine biologist lady who was studying it.

One thing about this series that instantly stood out from the beginning is that every scientist or expert (and clearly the production staff on the documentary) they had on seemed desperate to show that their little pet problem was caused by GLOBAL WARMING! Understandable, because there's big money in GW, and the next grant is always something on a researcher's mind.

This lady didn't find GW to be the cause, though. What she found is that the amount of dust blowing over from Africa was higher in the last few years, and that dust was affecting the Caribbean waters and coral through some process I don't remember. Apparently there's a big lake over in Africa that has dried up over the last several decades, and because of that there's more dust to kick up. I don't remember a lot the specifics, but it was an interesting piece.


No doubt, idiot tourists who don't know how to dive/snorkel near coral without killing it have not helped the matter either.

[fastfilm]

Just returned (july 4) from a month in the Virgins and want to point out the dangers of extrapolation from limited examples. This is our eighth charter in as many years, two weeks to a month at a time. Our range is generally from Vieques to Virgin Gorda with lots of time on the south shore of St. John in recent years. We snorkel one and a half to three hours a day most days. This year we spent more time in the BVI's, two five day trips, one in early June with our kids and their college friend and one end of June with our regular sailing friends, two other couples. On the first trip, we were pleasantly surprised by the health of the coral compared to our last time spent in the BVI's two years ago. Lots of healthy, colorful growing coral and a surprising number and variety of fish. We saw this at the usual popular spots as wel as the more out of the way spots. Indeed, the Caves on Norman Island, which we visited largely because our daughter wanted to show them to her college friend and party on the Willie T after, were teeming with life and ranked as my favorite spot on the first trip. The BVI's were also emptier than I have ever seen them. There were fewer boats, fewer charter boats, and empty anchorages and mooring fields.
The second trip, about a week later, there were fewer fish in the same spots. There were many more boats, almost as many as usual, though still on the low side. The Saharan dust turned the sky smoggy brown and seemed to contribute to some respiratory distress for all six of us on board.
That said, this is still just some random data. The impression of the nine people on our visits was that coral and water were healthier than last ime we were there, both in the BVI's two years earlier and around St. John from the year before. There are fields of dead and broken coral, particulary staghorn, what one book I read labeled coral graveyards. The locals I have talked to attribute much of this to storms which break the coral. They are worried less about this than about stresses which could limit or prevent coral regrowth.
Sorry to ramble but this is an area I love and the waters are precious. The mechanisms at work are complex. For example, what led to the drying up of that lake in Africa?
A simpler question. Does anyone know the story of that good sized workboat that is on the rocks around Round Rock in the BVI's? We stayed too long snorkeling at Fallen Jerusalem to get close enough to check it out.

[GordMay]

Lake Faguibine water levels depend upon the Niger River flood basin catchments, where rainfall has fluctuated wildly during the 20TH century.
In the late 80's early 90's, an extended draught led to a complete drying of Lake Faguibine.
Despite relatively normal rainfall in more recent years, Lake Faguibine remains nearly dry.

* A 2003 Columbia University study linked changes in sea surface temperature to drought in the Sahel during the 1970s and 1980s.

See ➥ Drying of Lake Faguibine, Mali : Image of the Day

And ➥ http://www.unep.org/pdf/Lake-Faguibine.pdf

[osirissail]

All the above reasons are valid contributors to the loss of coral reefs. In area of high concentrations of divers and snorkelers one primary cause of the loss of coral are the thousands of snorkelers and divers who naturally "warm their wetsuits" from the inside after entering the water - natural reaction of the human body when entering water. But in areas without large concentrations of humans other factors operate including one very significant one that is not talked about except in the highly technical journals - - Sahara dust storms. During years of significant Sahara droughts and dust storms the Atlantic Ocean and the whole Caribbean is blanketed by red dust blown by the winds clear across the ocean. Nah, too far - you think? Nope, the island of Bermuda and Antigua are totally the result of Sahara dust blown across the ocean, the original volcanic island or earth crustal island has been worn down below sea level and what is left is the Sahara dust that collected on the windward side. Lack of, or minimal hurricanes during a season is primarily the result of Sahara dust in the upper atmosphere blocking the sun from heating the ocean waters. Local inhabitants have long known that "hazy days" are good weather news and clear days bad.
This Sahara dust also works it way down onto the reefs and blankets them. Of course, major sewage outflows from many of the islands - many of which do not have sewerage plants/ pipes, etc.; over-fishing by locals (if it moves they have eaten it - (they are now taking very juvenile fish as the bigger ones are all gone); and hundreds of other minor, but significant factors when added together are all adding up to disappearing reef systems and fish.
Locals have no concept that when you "break the food chain" at the bottom, all the fish up the food chain soon disappear. Dolphins disappear; big sharks disappear; Tuna, Wahoo, and other game fish disappear. The local fish markets are now almost all selling sand sharks and barracuda.

[Gilbo]

The original post says the most significant area of damage is the baths. I live in the bvi and the most obvious reason the damage is being done there is the cruise ship industry. over the last couple of years the numbers of cruise ships visiting the bvi's has grown exponentially and guess where the most popular place to put these masses of people... the baths. It may be a stereotype but cruise ship passengers in general are not educated in things like coral preservation... i see them standing on the reefs kicking coral with fins etc. The island of Fallen Jerusalem just SW of the baths has lovely coral because not many people visit there. There are other factors at play most of which have been mentioned, but I can tell you for certain that the reefs on the "tourist map" baths, caves etc. are definitely less healthy than the more remote reefs.

On the subject of bleaching, the bvi had a particularly warm summer a couple of years ago, raising the sea temp a couple of degrees higher than normal. Much of the coral was bleached but as bstreep said that just means they are stressed and have expelled the zooanthellae (bacteria which help them digest food and give the colour) but most of the bleached reef has returned to normal since then.

[osirissail]

There are many a hundred different things that will cause coral death, etc. - the majority being human activity. But another natural one just popped up on the environmental/scuba news (it was in the DAN magazine). Algae blooms come out of the Orinoco River of South America (eastern Venezuela area) and last year a major one came out and rode the Orinoco Flow (current) through the lower windward islands and joined the Caribbean flow and it ended up in the Virgin Islands where the water went from normal "gin clear" to cloudy green and murky. The dive operators were bitching about it and where it came from and finally it was traced all the way back to South America - talk about interconnected ecosystems!

[sailvi767]

I dive in the BVI 6 to 8 times a year. I have not noticed a major change in the last 10 years. In fact the snorkling at Monkey Point the last few times has been the best I have ever seen in terms of fish life. I think a lot depends on luck of the draw and weather conditions.