|An Ecosystem Is The Entire Environment Of A Living Thing
A community of animals, plants and microbes, along with the aspects of the
environment which sustain them, such as air, water, soil and minerals.
They are linked together in nutrient cycles and energy production. An ecosystem is
the interconnections of all of these parts that help sustain the living aspects of this
environment. The Everglades is a good example of an ecosystem.
In the Everglades, so much depends on the forbearance of alligators. The largest
reptile in all of North America, Alligator mississippiensis is most easily observed in
winter, the season of shrinking sloughs. The resting time. You can see them on the
borders of canals and freshwater pools, where they appear to have plopped down,
exhausted, as though their short legs could not possibly have hauled that ample bulk
another step. On land at least, an alligator seems like an extravagance of nature, a
profligate accumulation of mass. The broad mouth hinges open like the hood of a car.
Often the only movement is in the eyes.
Saving the Alligators
During late winter and early spring, when the Everglades are at their driest, and
fish, the chief food of alligators, are most difficult to find, these inscrutable
reptiles use the brawn of snout, legs, and tail to bulldoze down through the peaty
Everglades soil. Water, never far from the surface, pools in these gator holes, and
the fish and invertebrates that collect in them soon draw wading birds such as
egrets, herons, ibis, and storks. In June, a month or two after mating in these
oases, female alligators plow mud and rotting plants into mounds along the sawgrass
ridges, then lie across the top and drop eggs by the dozen into a hollow they've worn
in the center.
The rain falls and the water rises. The females wait. Even in the best of years, the
Everglades are a capricious place, where months of summer rain bring abundant water
to the sawgrass and months of winter drought take it away, confining most food to
the deepest bowls in the underlying limestone. In the dry season, most Everglades
animals are wanderers in search of this receding nourishment, for in this place water
determines what lives and what dies.
In building their nests, alligators respond to an instinct honed over millennia, a
precise gauge of how many inches above the June level of water their eggs must lie
to remain safe. The landscape dictates their urges. In drought years, when low
water means fewer fish, the alligators may not nest at all, while in flood years the
nests may be inundated and the eggs drowned. But natural cycles are tuned to the
long run. When the muffled cries in the mounded peat stimulate the females into
digging the hatchlings free, chances are that the Everglades they are born to is an
Everglades rich again in food.
Or so it was when alligators were the reigning animals in the Everglades. In the last
century they have been steadily displaced by human ones, whose vision has greater
scale, it seems, but less understanding. Since the early 1900s, more than half of
what was once Everglades has been drained and developed. Here, where the tropical
and the temperate meet, gator holes have given way to vacation homes, while sugar
cane and winter vegetables have replaced the pond apple and sawgrass that once grew
in this "reclaimed" soil.
But human engineers have not yet stopped the summer rains. Before the arrival of
developers, the rain filled Lake Okeechobee to the north until its waters spilled over
its banks and flowed southward at a snail's pace in a shallow sheet 50 miles wide.
Now the human engineers shunt this water away from south Florida and direct it
instead to a variety of compass points, driving it along 1,400 miles of canals and
levees with some of the largest pumps in the world, eighteen of them to be exact,
pumps capable of sucking water off the land at a rate of more than 20 billion gallons
To protect the human investment, the water is channeled by the shortest and
quickest route to the sea, or it is spilled into marshes away from the man-made
world. Overseeing the master plan is the U.S. Army Corps of Engineers. Assisting it
is the South Florida Water Management District, which draws up the daily schedules
and graphs. Its motto, "PROTECTING THE EVERGLADES SINCE 1949," adorns the
doormats in its West Palm Beach offices.
The motto derives from a requirement that the system of flood control also allow for
the protection of fish and wildlife as well as for the delivery of water to Everglades
National Park. Protecting this ecosystem is a very important, ongoing project which is
always in need of additional funds.
Often, however, fulfilling this requirement undercuts what Florida taxpayers have
always considered the more important ones: controlling floods, supplying water for
drinking and irrigation, and even facilitating navigation. To this day, the engineers and
hydrologists haven't worked out the kinks. In times of little rain, water has been
withheld north of the Park, while in times of flood it has been sucked from the
settled landscape and discharged in sudden destructive surges to the southern
In 1963, for example, the Corps of Engineers completed L-29, a levee and canal
along a section of the northern border of Everglades National Park. As it happens,
the early 1960s were a time of fierce drought in south Florida, and the levee choked
off the last of what little water was arriving from the north. Alligators, already on
the decline from overhunting, particularly suffered. Back in 1958, one researcher
had counted 300 alligators in a one-mile section of the Park's Shark River Slough;
when he returned to the same section in 1966, he could find only three.
Two years later, another scientist calculated that one million alligators had once lived
in the area now occupied by the Park; now, he concluded, there were only 10 to 20
percent of that. Panicked resource managers scurried through the sawgrass, trying to
find water for this vanishing wildlife. Using dynamite, they blasted gator holes in the
Park officials begged for water. As a result, Congress in 1971 ordered that a
minimum amount be delivered monthly to the Park. Canals leading south were widened
to facilitate the process. The problem now became too much water. The scheduled
deliveries worked during some months, but at times of heavy rain the Park got huge
additional slugs of water that had been removed from areas where it threatened
farms and cities.
Alligators, which had begun to increase in numbers after being declared endangered in
1973, now had trouble producing young. Their nests, so carefully positioned according
to timeless reptilian calculation, were inundated and lost. They are in danger still,
although to what precise extent remains unclear.
A small, sturdy an with a full gray beard, biologists at the South Florida Research
enter at Everglades National Park worry about the survival of the wood stork.
Saving the Wood Stork
Biologists haver focused on the wood stork as an indicator species for the health of
the Everglades ecosystem. He once told a reporter that he has snapped more than a
thousand tags onto the wings of wood storks. He has concluded that the birds are
abandoning Everglades National Park in ever greater numbers for more suitable, if
less protected, habitat to the north, a trend that has been accelerating since the
One of the endangered species is the wood stork. In fact, biologists have found that
the number of storks nesting in the Park has dropped by 80 percent since the 1960s.
Unless its habitat returns, the stork will soon no longer nest there at all.
Although the wood stork, a large bird as ungainly when perched as it is graceful when
soaring, is an endangered species, biologists are certain that the true significance of
its decline in Everglades National Park will be followed by other species of wading
birds. Estimates are that the population of all these birds has declined by 90 to 95
percent over the last half-century.
"Ecosystem collapse" can be difficult to observe in a landscape as rich as the
Everglades, but this has always been an extremely complicated system to understand
There is tremendous seasonal variations with dry seasons and wet seasons existing
within a larger cycle of drought and flood. Over the flat landscape several habitat
types developed: open ponds; sloughs with aquatic plants such as water lilies floating
on the surface; wet prairies with emergent vegetation such as rushes poking through;
uniform expanses of sawgrass; scattered stands of bald cypress; bay heads and
willow heads; hardwood hammocks; forests of slash pine; and along the estuaries of
the coast, some of the finest mangrove forest in the world.
Faced with such a landscape, animals must learn to adapt quickly. Alligators become
engineers, for example. One reason birds do so well in the Everglades is their
mobility. When one pool dries up, they can fly to another. Like alligators, many
species adjust their nesting habits to water levels. Wood storks are masters at this.
Historically, they nested during November and December in Everglades National Park,
at the early part of the dry season. At that time of year, many higher elevation
marshes near the deeper sloughs still had water and fish, and the storks could feed
there when not tending their eggs. Gradually, as the season progressed, the
peripheral marshes dried up, and in response, the storks moved their feeding to the
deeper sloughs. The timing worked so that the stork chicks appeared near the end of
the dry season, in March and April, when fish, concentrated in the remaining pools,
were at their easiest to catch.
Aside from the rain that falls within its boundaries, nowadays the only water in
Everglades National Park is the water that the government sends there. With
wildlife protection such a low priority, the predictably unpredictable has become, over
the last 45 years, simply unpredictable. The Park is so dry in November and
December that the peripheral marshes have no fish in them, and the storks have
adapted by postponing their nesting.
They now must wait to form colonies until February and March, when the deeper
sloughs become shallow enough for fishing. Unfortunately, this means the chicks
emerge in May, June, and July. In most years, enough rain has arrived by then to
disperse the concentrated fish, and as a result, adult birds can no longer efficiently
collect enough food for their young. These are the months when the landscape signals
wood storks to abandon their colonies. Left behind, the unfledged chicks starve.
The Future of This Ecosystem
There is no other habitat in the world quite like the nascent Everglades, and there
has never been a project with the breadth of this Everglades restoration. It
represents a turning point, a public recognition that we can go too far in letting a
vast wilderness decline and that we now have an opportunity to prove that scientists
and environmentalists and even bureaucrats can for the first time return an entire
ecosystem to health, even if it must be kept alive on a kind of mechanical
life-support. The future of wetlands in much of the world may depend on getting this
Crossingham, J. Endangered Pandas (Earth's Endangered Animals). 2005.
Askins, R. A. Saving Biological Diversity: Balancing Protection of Endangered Species
and Ecosystems. 2010.