|The Ecological Detectives|
Florida is our southeastern frontier, the elongated big toe of North America testing the waters of imagination and excess. It's where children revel in Walt Disney's calculating empire of cartoon fantasy, where men and women begin their trips through weightlessness to the moon and stars, where the old go to fish and golf and prepare themselves for the sweet hereafter.
Robert Halley (left) and Steven Miller in the mangrove-dotted waters of Florida Bay.
The southern tip of Florida is nature's analogue to this man-made world of overheated whimsy. The region contains the Everglades, a landscape of shifting light and penetrating smells, an extravagant canvas for the diversity of life, unruly and largely inaccessible without considerable effort. In biogeographic terms, south Florida's dark mangrove creeks and ancient cypress swamps, its eye-bending sawgrass prairies and soupy estuaries sit precisely where the temperate meets the tropical, creating the nation's only subtropical wilderness. A canoe moving through the brackish primordial soup of a south Florida mangrove creek at the right time of year cuts through so many newborn fish that their roiling mimics the sight and sound of rain falling on water.
South Florida has historically been the hiding place of defiant Indian tribes, runaway slaves, moonshiners, drug smugglers, and murderers - not to mention alligators, crocodiles, poisonous snakes, and more than a dozen species of mosquitoes. For most of its history, the region has been an emblem of the untamed run amok, a wasteland made all the sweeter for having been drained, cut, straightened, poisoned, and burned into the cities of Miami and West Palm Beach.
For 300 years, this industry of elevating the primitive into the civilized has coexisted with - and mostly overwhelmed - the persistent notion that the natural world of south Florida is not primitive but is, in fact, one of the most magnificent works of either God (at first) or evolution (more recently). To the few who, until recently, ventured into it, the Everglades was, as Marjory Stoneman Douglas described it in her 1947 classic, The Everglades: River of Grass, "one of the unique regions of the earth, remote, never wholly known."
It was in response to this other view of south Florida that in 1947 the federal government established Everglades National Park and, in later years, set aside other preserves in the Big Cypress to the north and at Key Biscayne and the Tortugas to the south. Yet, as it was shielding small portions of south Florida from the developers and speculators, the government, through the U.S. Army Corps of Engineers, was also becoming the region's chief despoiler, digging canals to drain the land and straightening and "channelizing" the Kissimmee River at the head of the south Florida ecosystem. The Corps' masterpiece, however, came on line in the early 1960s, when it finished the historic Central and Southern Florida Flood Control Project: 1,400 miles of canals and levees, 150 gates and spillways, and sixteen of the largest pumping stations the world had ever seen. The constantly shifting sheet flow of fresh water through the Everglades - which was once 100 miles long and forty miles wide - was now transformed into a uniform "schedule of water deliveries" designed to produce the predictability required for large-scale agriculture and for suburbs that don't periodically revert to swamps.
The ecological damage this schedule would produce was immediately apparent. In 1962, when a prolonged drought followed the completion of the Corps' project, the combination so reduced the amount of water flowing into Everglades National Park that managers desperately dynamited holes in the limestone to create pools for alligators, which were rapidly disappearing. In 1994, John Ogden, then a biologist with the park, estimated that the number of wading birds nesting there had declined by 95 percent since the 1930s. By the time of Ogden's study, agriculture and urban sprawl had reduced the area covered by the Everglades by half. "We once had an ecosystem that we called the Everglades," Ogden is fond of saying. "Now we have a big wetland out there, and we still call it the Everglades. But it's not."
The Everglades is only the most famous example of what has been happening to all of south Florida, from Lake Okeechobee down through the Florida Keys and the coral reef just offshore. Alarmed at the decline, national environmental groups have joined local ones to form organizations such as the Everglades Coalition, which has been steadfastly working to restore the area's biological heritage. By the early 1990s, south Florida had become the focus of the largest environmental restoration project ever attempted, a project that will eventually cost billions of dollars. Even the channelized Kissimmee River will be released, allowed to return to its ancient route. Ironically, helping to lead the way for all this is the U.S. Army Corps of Engineers.
Robert Halley '71 Sc.M. and Steven Miller '75 were among the scientists drawn to this dream of restoration in the late 1980s and early 1990s. Born in different parts of the United States and specialists in different scientific disciplines, they are united by two things: their time at Brown and their love for south Florida's natural world.
Of the two, Halley has more experience in the Sunshine State. A twenty-three-year veteran of the U.S. Geological Survey (USGS), he spent the first six years as a scientist based in Miami and the next six years in Denver before being sent to the Woods Hole Oceanographic Institute on Cape Cod. In the 1980s, as the USGS responded to public concern about the condition of the environment, it sent Halley to Woods Hole to help develop a coastal program to complement its research on ocean geology.
Halley faced a similar task when, in 1989, he moved from Woods Hole to St. Petersburg, Florida, and, with five colleagues, opened the USGS's national coastal center. One immediate assignment was to analyze Florida's complex coastline and the limestone that, among other things, contains most of the region's fresh water. Today the office employs a staff of fifty. Halley, who also holds an adjunct faculty appointment in the departments of geology and marine sciences at the nearby University of South Florida, has meanwhile become a USGS representative on the interagency committee monitoring the research conducted for the south Florida restoration.
Until this century, water during the wet season spilled over the south rim of Lake Okeechobee and into a plain of sawgrasss 100 miles long, forty miles wide, and only a few inches deep. Even today, the water in the Everglades appears still; in fact it is slowly moving south to Florida Bay.
Although Halley still must handle the occasional managerial project, in 1992 he gladly transferred the administration of the south Florida office to others so he could return to his first love: science. "I did my undergraduate work at Oberlin," he says, "and was a premed student until the spring of 1968. Then, in 1969, we landed the first astronaut on the moon, and geology suddenly became a big thing. I was hooked." What fascinated him, he says, is the sense of time geology opens up, of the distant past hidden in today's rocks. "I think it was [anthropologist] Loren Eiseley who said that geology's real contribution to mankind is this concept of geological time," Halley explains. "No other field except astronomy has such a sense of time. You can pick up a rock and in it is information on the way things were a million years ago. We don't normally think about time like that."
Halley's love of geology blossomed at Brown and continued through his Ph.D. work at the State University of New York at Stony Brook. As a master's candidate at Brown, he specialized in the study of limestone under his adviser, Leo LaPorte, who later left Brown for the University of California at Santa Cruz. But Halley's greatest intellectual influence was Professor Emeritus of Geological Sciences John Imbrie, who, he says, "is one of those amazingly original people who influences a whole generation of scientists." Imbrie pioneered techniques of taking sediments from the ocean bottom and, by analyzing microscopic fossils, reconstructing ancient environments and climates. Those techniques are central to Halley's Florida work.
Halley's focus is Florida Bay, the 850-square-mile estuary that lies between the tip of peninsular Florida and the Florida Keys. Protected by the Keys, the bay has a bottom that is a complex mosaic of mud banks and shallow depressions. Some mud banks are so close to the surface that red mangroves grow on them. These further shield the depressions in the bay, which are, in effect, petri dishes full of rich, subtropical broth of various salinities. It would be difficult to overexaggerate the biological productivity of Florida Bay. It is a major nursery for fish in the Gulf of Mexico and a feeding ground for millions of birds ranging in size from least terns to greater flamingos.
Unfortunately, Florida Bay is also the last stop in the south Florida ecosystem. Before south Florida was drained for development, water moved in a slow-moving seasonal ballet from Lake Okeechobee down through 100 miles of Everglades and into the bay. As the fresh water moved south, it acted as a huge solar collector, producing abundant energy to fuel a food chain of breathtaking biological diversity. It also seeped down through the peaty Everglades soil and into the limestone, recharging the Biscayne Aquifer, which is the water supply for most of south Florida. When at last the remaining water reached Florida Bay, it combined with the ocean water surging upward from the Caribbean to provide just the right saltiness for turtle grass to grow along much of its bottom and fuel the rich, food chain based there.
Since the completion of the Corps of Engineers' massive flood control project in the early 1960s, much less fresh water has been making it to Florida Bay. This was largely unnoticed until the late 1980s, when salt levels in the bay rose so high that vast areas of turtle grass began to die. In hydrological jargon, the bay went "hypersaline," with disastrous results.
Aquarius, the world's only underwater laboratory, rests on the Florida reef tract a few miles offshore from Key Largo, Florida, in sixty feet of water. It allows up to six scientists to study the reef for ten days without surfacing.
Publicity about the decline of Florida Bay led to wider concern about what had happened to the Everglades and all of south Florida. Many were quick to blame the ecological crash on almost thirty years of altered hydrology. But scientists were not so sure. If there is one characteristic that distinguishes south Florida's ecosystem, it is change. On various temporal and spatial scales, conditions are constantly shifting, from day to day, season to season, year to year, decade to decade, and probably beyond. One reason, in fact, that birds are so successful in south Florida is that its landscape appears to them as a buffet table continually being refreshed. If a bird's feeding area changes or becomes fished out, there is always someplace within easy flying distance that is just reaching its peak.
Could it be, scientists are still asking, that the changes in Florida Bay, though catastrophic to the biological conditions we have become accustomed to, are part of a larger natural cycle that we don't yet understand? Robert Halley's research is intended to answer such questions. "When ecologists started asking `What's wrong with Florida Bay?' one of the first questions was: what did it used to be like? If you are trying to restore an ecosystem, you have to know what you are restor-ing it to. We are taking the same techniques that John Imbrie pioneered to study what an area looked like hundreds of thousands of years ago and using them to figure out what it looked like 150 years ago."
Halley and his colleagues take mud-core samples from Florida Bay and then measure "proxies" in the mud. In this case, proxies are various isotopes that once circulated in the water and got locked into the shells of mollusks and of a single-celled protozoan called foraminifera, or, simply, forams. As the forams died, they piled up in the sediment, storing in their shells clues about the ecology of the bay at the time of their death. "The isotopes of oxygen," Halley says, "are proxies for temperature and salinity. The carbon isotopes are a proxy for biological productivity and can also tell us a lot about where the water at the time might have come from." Already, the work of Halley and his colleagues has revealed that a similar increase in salinity occurred in the 1930s. Was that a natural change? It so happens that the 1930s were when the first big successful drainage projects were under way in the Everglades; was the increase in salinity triggered by that? The most plausible theory so far is that the uncontrolled drainage of the first half of this century has so weakened Florida Bay that it can no longer absorb natural events such as prolonged drought. But the mystery remains unsolved.
Steven Miller faces a similar conundrum at his base in Key Largo, where he directs the Florida Keys research program for the University of North Carolina at Wilmington's National Undersea Research Center. Funded by the National Oceanic and Atmospheric Administration (NOAA), the undersea research program has six centers around the country; the one in Wilmington covers the entire Southeast, including the Keys.
Just as Robert Halley is trying to sort out the reasons for the ecosystem decline in Florida Bay, Miller, a marine biologist, is helping lead an effort to examine why coral diversity on the 220-mile-long Florida reef tract has been slipping downward over the past two decades. Like many reefs in the Caribbean and other parts of the world, the Florida reef, which is actually a series of ridges and channels running from Miami to the Dry Tortugas, has been suffering from "bleaching," which describes what happens when corals under stress expel the algae they need to provide nourishment. "It does appear," Miller says, "that abundance and distribution of coral disease have increased over the last few years. But is the increase a result of increased stress, and if so, what are the causes of that stress?" Some scientists have argued that the culprit could be global warming or an increase in nutrients transported by the oceans from increasingly developed coastlines. But such connections are far from proven, and in the case of the Florida reef tract, the area has been so poorly studied that even fundamental data are only now being gathered. The Florida Keys research program, for example, was begun only in 1991.
Miller's route to south Florida was more circuitous than Halley's. After attending high school in Minneapolis, he entered Brown intending to become a medical doctor. "The New Curriculum attracted me to Brown," he recalls. "And one of my science teachers strongly encouraged me to go. But I came from a public high school where you didn't work very hard and did real well, and when I got to Brown I learned that the same level of effort will get you nowhere." In other words, he adds, "I would describe my undergraduate career as uneventful."
South Florida's vegetable farms and sugar fields are on peat soil that was once part of the Everglades, which agricultural and urban development has cut in half. The ecological restoration underway there hopes to create an ecosystem that can live with its man-made surroundings.
He did, however, discover a strong liking for biology. After graduating with a biology concentration, Miller went to St. Croix in the U.S. Virgin Islands to visit a friend. He intended to spend three weeks and stayed four years, captivated by the underwater world of the Caribbean. Supporting himself with work as a bartender and waiter, Miller began taking classes at the now-defunct West Indies Laboratory, which was run by Fairleigh Dickinson University. When a job opened for a technician working with one of the world's leading coral-reef experts, Miller applied. One credential helped to distinguish him from the other applicants, he reports: "I have found that the undergraduate degree from Brown has been helpful. It offers instant credibility."
At Key Largo, Miller balances his time between conducting research and ministering to the needs of other scientists studying the reef. The centerpiece of the Florida Keys research program is Aquarius, the world's only underwater laboratory. Originally based off St. Croix, Aquarius, an eighty-ton structure that houses bunk beds, laboratory work stations, and even hot showers, was moved to a spot on the Florida reef in 1993, shortly after the area became the Florida Keys National Marine Sanctuary. Scientists apply to the research program to spend ten days living in Aquarius conducting underwater studies. "It was stunning how little had been done here on this reef," Miller says. "Until Aquarius, coral-reef biologists were going to different parts of the world to conduct research."
Despite the demands of the Aquarius program, which Miller administers, he has been able to make a few scientific observations that could help show how linked even this coral reef is to the peninsular south Florida ecosystem. In 1995, he led a multidisciplinary expedition of scientists that systematically gathered data from the entire reef, the first Keys-wide assessment of the Florida reef tract. "During this cruise," Miller says, "we saw evidence of recent die-off of several species of brain corals in the middle Keys. That would be consistent with Florida Bay water making it out to the reef tract."
Miller is not ready, however, to conclude that the reef is being damaged by man-made changes to the region's environment. "The corals that died," he explains, "died because they became covered with sediments from Florida Bay." Those sediments were most likely freed from the bottom of the bay when it suffered its massive turtle-grass die-off in the late 1980s and early 1990s. But what caused the turtle grass to die? Here is where Miller's and Halley's work meet: If Halley's work can help show that the turtle-grass decline was probably a cyclical, natural phenomenon, then the coral die-off Miller observed is most likely a natural event. But if the turtle-grass die-off is primarily due to the altered hydrology of south Florida, then we humans are not only killing off the Everglades; we're working on the reef tract as well.
Miller and Halley both emphasize that definitive answers are a long way off. Science, it seems, often moves according to geological time. Unfortunately, south Florida's natural world cannot wait aeons for restoration; its decline is happening far too quickly. Guided by scientists such as Halley, the replumbing of south Florida is proceeding cautiously, but proceed it must. Most researchers are convinced that enough is known to begin altering the way water moves down through the ecosystem so that the timing and spatial pattern of its flow replicate the presettlement condition as much as possible. The guiding principle is something called adaptive management, which specifies periodic monitoring to see whether a given restoration step is working. One thing is certain: no one knows what the south Florida of 2040 will look like, but almost everyone hopes it won't resemble the south Florida of 1990.
"What are our expectations about all this?" asks Steven Miller. "People want nature in south Florida and the Keys to be the way it used to be. But what does that mean? The way it used to be when? There are so many examples of our going in to try to restore nature. There are so many examples when we've been burned." This time, both men are determined to do what they can to get it right.