Saturday, May 10, 2014

Aragonite worth billions is being mined in the Bahamas ...Sometimes on a clear day you can't see the bottom

Dredging Money From The Bank

 

By Coles Phinizy:
July 06, 1970
si.com
 

Across the inky-blue Gulf Stream from Florida, near the sheer edge of the Great Bahama Bank, a new island is emerging from the sea. Although it bears the appealing name Ocean Cay, this new island is not, and never will be, a palm-fringed paradise of the sort the Bahamian government promotes in travel ads. No brace of love doves would ever choose Ocean Cay for a honeymoon; no beauty in a brief bikini would waste her sweetness on such desert air.

Of all the 3,000 islands and islets and cays in the Bahamas, Ocean Cay is the least lovely. It is a flat, roughly rectangular island which, when completed, will be 200 acres and will resemble a barren swatch of the Sahara. Ocean Cay does not need allure. It is being dredged up from the seabed by the Dillingham Corporation of Hawaii for an explicit purpose that will surely repel more tourists than it will attract. In simplest terms, Ocean Cay is a big sandpile on which the Dillingham Corporation will pile more sand that it will subsequently sell on the U.S. mainland.

The sand that Dillingham is dredging is a specific form of calcium carbonate called aragonite, which is used primarily in the manufacture of cement and as a soil neutralizer. For the past 5,000 years or so, with the flood of the tide, waters from the deep have moved over the Bahamian shallows, usually warming them in the process so that some of the calcium carbonate in solution precipitated out. As a consequence, today along edges of the Great Bahama Bank there are broad drifts, long bars and curving barchans of pure aragonite.

Limestone, the prime source of calcium carbonate, must be quarried, crushed and recrushed, and in some instances refined before it can be utilized. By contrast, the aragonite of the Bahamian shallows is loose and shifty stuff, easily sucked up by a hydraulic dredge from a depth of one or two fathoms. The largest granules in the Bahamian drifts are little more than a millimeter in diameter. Because of its fineness and purity, the Bahamian aragonite can be used, agriculturally or industrially, without much fuss and bother.

It is a unique endowment. There are similar aragonite drifts scattered here and there in the warm shallows of the world, but nowhere as abundantly as in the Bahamas. In exchange for royalties, the Dillingham Corporation has exclusive rights in four Bahamian areas totaling 8,235 square miles. In these areas there are about four billion cubic yards—roughly 7.5 billion long tons—of aragonite. At rock-bottom price the whole deposit is worth more than $15 billion. An experienced dredging company like Dillingham should be able to suck up 10 million tons a year, which will net the Bahamian government an annual royalty of about $600,000.

On the basis of such big, round figures, the mining of aragonite seems to be a bonanza operation. In reality it is still a doubtful venture for both Dillingham and the Bahamas. For Dillingham the big question is whether the aragonite can be hauled to market cheaply enough to compete with other suppliers. For the Bahamas the question is more provocative: What effect will the dredging have on tourism, the major industry of the islands? Two years ago the Bahamian government made a study of the tourist trade and found that out of a gross business of $193 million, about $52 million in wages and profits ended up in Bahamian hands. The bright beaches and clean waters, the deep reefs and shallow coral gardens, the game fish of the fiats and the bigger game fish of the open sea—these are the basic assets of tourism that are apt to be diminished by a dredging operation.

Dredging is inherently a dirty business. Worthy servant though it is, a hydraulic dredge simply does not fit into the natural scheme. The spume created by the cutter of a dredge's maw and the cloudy water from its discharge pipe are usually more than God's little marine creatures can tolerate for long. The Bahamian government does not say much about the aragonite operation, and the Dillingham Corporation says almost nothing. In this day when all sorts of strident anti-pollutionists are at the palace gates, reticence on the part of anyone who is roiling the beautiful Bahamian waters is understandable—understandable but also deplorable and, in the long run, stupid. It is human nature to suspect big operators, particularly the big, quiet ones who—true or not—seem to be making money hand over fist. By their reticence the Dillingham people are inviting distrust and as a consequence will probably be charged with crimes they have not committed.

A mile or two west of the Dillingham Corporation's artificial island, Ocean Cay, charter boats run the edge of the Gulf Stream in quest of billfish and tuna. Often, on the ebb tide, cloudy water driven by prevailing easterly winds moves from the Great Bahama Bank over the deep. This cloudiness is sometimes caused by long swells born of distant storms and sometimes by stiff local winds that kick up a fuss in the shallows. When the Dillingham operation gets going full blast, it will certainly add to the natural siltiness. In the future the cloudy water that fishermen encounter may be the work of a Dillingham dredge or it may be an act of God—or a combination of the two. It will not matter which. Since fishermen are human, innately suspicious and easily disgruntled, they will be inclined to blame all the dirty water on Dillingham.

One of the Dillingham mining concessions completely surrounds the Joulters Cays, a bonefishing area of proven worth. In the future, when the water is cloudy and the bonefish do not respond to the lure as they did of yore, the unlucky anglers will not take God to task; they will curse Dillingham.

Northwest of Ocean Cay there is a deep and little-known reef that stretches intermittently for eight miles along a submerged terrace—a rich and spectacular range. There are narrow canyons and caves in this drowned scarp, and a profusion of fish large and small. From the way the living corals spread over the buttresses of ancient rock it is obvious that the existence of the deep reef depends on a prevalence of clean water from the Gulf Stream. In the future if the water is often cloudy and the life of the reef seems to be wasting away, the scuba divers probably will blame Dillingham.

What effect aragonite mining actually will have on any parcel of the Great Bahama Bank is still a wild guess since no one has a sufficient grasp of the problem. Aragonite is fairly heavy stuff, weighing almost three times as much as water. When stirred up, the largest granules sink quite rapidly, but in a hundred tons of the deposit there are a couple of tons of very fine stuff that can stay in suspension for a week. In that time a large cloud of such material may travel 30 miles, riding the tide and the whims of the wind, casting shadows over rich marine areas that seldom suffer under such a pall. In scientific papers already published on the Great Bahama Bank there is good information about the movement of water, but none detailed enough to indicate just how a constant stream of cloudy water is apt to wander from a given location.

Before any biologist could assess the effect of aragonite mining, he would have to know a bit about the operation, specifically how the dredges are to be used and the expected rate of production. The Dillingham Corporation has declined to give out such information, maintaining that it might be "a benefit to other suppliers of limestone on the mainland." Since the corporation has exclusive rights to the Bahamian drifts, and will be using mining techniques different from those employed in quarries, it is hard to see how such basic information could possibly benefit rival suppliers on land.

The Dillingham Corporation claims that the Bahamian government has already had "ecological studies" made in the area of Ocean Cay and is having "continuing studies every 90 days." Although this claim is a slight overstatement, it is true that, at the request of the Bahamian Ministry of Agriculture and Fisheries, last December Dr. Durbin Tabb of Miami's Institute of Marine Science did make a two-day survey of the area. Dr. Tabb was obliged to conduct his investigation on a budget of $1,500 and without a complete idea of the dredging technique or any knowledge of the expected rate or continuity of production. On the basis of his hit-and-run survey, Dr. Tabb concluded that there was no solid reason why the relatively sterile aragonite drifts should not be mined, provided the operation was kept under surveillance. He was particularly concerned with the effect the altered bottom contour might have on turtle-grass beds in the shallows and what effect the silt from dredging might have on tuna migration in the deep.

Confronted by concern among biospecialists and by rumbling in the press, last month the Bahamian Government Information Services put out their first news release on the aragonite operation. The release emphasized Dr. Tabb's solid opinion that the aragonite areas are undersea Saharas of little biological worth. It said nothing about what might happen when the dust of these submerged Saharas is kicked up by a dredge and drifts over richer areas downstream.

A large hydraulic dredge with a two-foot throat can easily pick up 10,000 cubic yards of loose aragonite in a day. In the process it also sucks up at least six times as much water—roughly 10 million gallons. When that much silty slurry drains directly back into the sea, it creates quite a cloud—virtually an endless stream since dredges usually operate day and night in the interests of economy. Under their contract with the Bahamas, the Dillingham Corporation has the right to pile up 12 artificial islands. Logically, in the coming years the corporation will situate these islands so that dredges with a practical range of several miles can discharge aragonite and slurry directly onto them. In such case the cloudiness will certainly be diminished. The extent of it will depend largely on how much silt the head of the dredge stirs up and how much remains in solution when the slurry drains, or is pumped, off the islands.

When a storm of gale force sweeps the Bahamas it produces cloudy water that may persist over vast areas for as long as a week. A hundred dredges toiling around the clock could not possibly create a condition comparable to what the Bahamas get when a hurricane gives them a good dusting. But there is a difference. The storms of nature are a very sporadic blight. They have occurred throughout many yesterdays and will come again tomorrow. The life of the sea, often hanging in fine balance, has accommodated to that inevitability. Human pollution is a brand-new burden. The unnatural filth suddenly contributed by man may be only a pennyweight of the total, but that is sometimes enough to tip the scale.

Drab though it is to the naked eye, a mat of turtle grass on the sea floor is quite a vital place. On the slimy blades of grass there are a host of minor organisms that feed on smaller organisms and are themselves eaten by larger ones. Seven years ago Dr. Donald Moore of Miami's Institute of Marine Science found, among other things, 28,000 univalve and bivalve mollusks in one square meter of turtle grass. Ten years ago, using seines and push nets, Victor Springer and Andrew McErlean of the Florida State Board of Conservation sampled a shoreline flat of the Florida Keys one day each month for a year. Although the sand and grass tract they searched was less than two football fields in area—and the water did not exceed five feet in depth—Springer and McErlean found 106 species of fish. Grunts, snappers, gobies, porgies, blennies, wrasse, groupers, barracuda; yellowtail and tripletail; batfish and lizard fish; goatfish and parrot fish; big-eyed jacks and little queen triggers; pipefish and filefish and spadefish; bonefish and surgeonfish; needlefish and thread herring—you name it, Springer and McErlean found it. A good number of fish they netted in the shallows were juveniles of species that subsequently take up residence on coral reefs in deeper water.

Many fish that dwell in, on, or around living coral return to the grasses behind the reef to forage. Some of these reef dwellers go to the grass to feed by daylight, others hole up by day and feed at night. As Dr. Gilbert Voss of the Institute of Marine Science puts it, "toward evening, between the reef and the turtle grass, there can be a real traffic jam." While serving at the University of Puerto Rico three years ago, Dr. Jack Randall examined the stomachs of 5,526 reef fish of 212 species. Curiously, although soft coral polyps are easily ingested, and should be nourishing, only 10 of the 212 species that Randall examined had eaten any coral—none of them more than a trace. A preponderance of the species Randall studied were directly or indirectly dependent on the turtle-grass beds for nourishment. Sea urchins, which eat turtle grass, would seem to be too painful a mouthful for almost any fish, yet Randall found a considerable percentage of urchins in the stomachs of 34 reef species.

In the clear waters of the Bahamas today nursery and feeding grounds of turtle grass commonly prosper 25 feet down and have been found at 40 feet. By contrast, for want of light in the turbid waters of Biscayne Bay around Miami; turtle grass is no longer found much deeper than 10 feet. To sum it up, when a dredge forces a turtle-grass bed out of business, the curtain also comes down on a hell of a big variety show.

It is a common fallacy of man to believe that a profusion of other forms of life is proof of their prosperity and permanence. Despite all its variety and oddity, despite its apparent extravagance and luxuriance, a coral reef is often a desperate place. As viewed through a diver's mask, magnified to heroic proportion, the finest reefs of the Bahamas seem to be durable, monumental works of long standing. In truth the very best of Bahamian reefery is no more than a thin veneer—a very recent culture of reef corals that has managed to take hold and spread mostly in the past 5,000 years under conditions that have probably never been ideal.
When silt particles settle upon them, the polyps of reef-building coral must work to get rid of the intruders. When the workload becomes excessive, the polyps are forced to close shop for a while—and sometimes forever.

Today, largely because of the work of the late Dr. Thomas Goreau of the University of the West Indies, scientists recognize that turbid water has still another adverse effect on reef corals. In clear, shallow water of 10 feet the coral Acropora palmata—one of the primary reef builders—is usually massive, thick-limbed, on all counts prosperous enough and strong enough to hold its own against the constant invasion of borers and the pummeling of the sea. A mere 10 feet deeper, the same species, if found at all, is much weaker in structure, and growth by actual measurement is considerably slower. When cloudy water persistently reduces the light, the coral is, in effect, thrust to a depth where it cannot build and where it may not survive.

When Astronauts return to earth, the moon dust is vacuumed from them and they are quarantined for two weeks. The moon dust is reputedly sterile, but we take no chances. The Dillingham Corporation and the Bahamian government are willing to gamble with the sterile dust of the aragonite drifts. When there are so many specialists today who can minimize the risk, why do they gamble? Primarily, it seems, because Dillingham prefers to hoard the truth and the Bahamian government is too skinflinty to pay for a proper investigation. In a day when we are all getting a trifle sadder and wiser about the environment, this view is as murky as the waters surrounding Ocean Cay.

si.com 
July 06, 1970