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of us are bunched together in a small blue boat, enjoying a cool
breeze under the relentless Venezuelan sun. A maze of islands surrounds
us, little green gumdrops whose reddish-brown shores slope steeply
into forested interiors. Powered by a moody Yamaha motor, we chug
our way toward Chiguire Island, a smidge of dry land named after
the giant aquatic rodents that hang out there. As we draw closer,
a ball of orange fur becomes visible at the top of one of the island's
largest trees, a vigilant howler monkey not willing to share his
space with other primates. This invasion of humans must be nothing
short of terrifying to an animal that has lived most of its life
peacefully on this little island retreat.
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| A view from Iguana
Island to mainland Venezula in the distance. |
| photo:Brad
Balukjian |
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Our destination is just one of hundreds, maybe thousands, of islands
in Lake Guri, a vast 4,300-kilometers-square hydroelectric compound
in the largely uninhabited state of Bolivar, Venezuela. The most
humbling statistic is that the lake is 1.6 times the size of Rhode
Island, my home state. For two months this past summer, I joined
a dozen or so scientists from around the world in calling this muddy
oasis home. While we each had different research projects and organisms
to study, we shared the goal of deciphering exactly what was going
on in this system, a natural laboratory unlike any other in the
world.
Lake Guri was formed artificially with the construction of the
Raul Leoni Dam in 1968 and grew in size in 1986 when the second
stage of dam construction was completed. Its purpose is to provide
water-powered electricity to large regions of Venezuela. When the
lake was enlarged in 1986, the flooding of the land formed an archipelago
of green-studded islands that shed their former lives as hilltops.
The remains of the trees are still visible in the "ghost forest,"
the chilling name given to the rings of dead trees that poke above
water, their bases buried underwater some fifteen or twenty meters
down like the lost city of Atlantis. A drought this summer left
the water extremely low and revealed whole thickets of this ghost
forest, creating magnificent graveyards of once-dominant trees now
treading water. Their trunks are clumped so close together that
navigating a boat between them requires ace piloting skills and,
more often than not, the ability to duck and brace for collision.
Where most islands in the world were formed or separated from
the mainland hundreds or thousands of years ago, these islands are
a mere fifteen years old, making them ideal study sites. The plants
and animals that survived the flooding are now confined to the borders
of the islands, no longer able to roam the once-continuous land.
This restriction on their movement has produced some unusual and
ominous ecological phenomena that have been monitored by our research
program for several years.
We ram our boat into the mud bank of Chiguire Island and claw
our way up to its vegetated crown. The outer thickets resist our
intrusion, but a few scratches later we penetrate to the interior.
At just over half an acre, Chiguire is covered in trees both young
and old. Save for some hardy leaves, the island is like a skeleton
picked dry, a tangle of pale gray branches wrapped up by twisting
vines.
John Terborgh, James B. Duke Professor of Environmental Science
and leader of our group, says in his syncopated staccato voice,
"Look at this God-forsaken place. And monkeys live here. It's
amazing that anything can live here." The adroit veteran ecologist
has thin, silvery hair pushed back straight from his long, tanned
face, and a trim gray mustache. In his decades of working in the
jungles of Peru and Venezuela, he seems to have found the fountain
of youth. Agile and upbeat, Terborgh is often seen around camp wearing
a tongue-in-cheek T-shirt that reads, "Thank God for Evolution,"
a gift from his graduate students at Princeton many moons ago.
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| Treehugger: The
author and his subject |
| photo:Brad
Balukjian |
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Caught up in our exploration of the island, we forget about our
howler-monkey host up above, who reminds us of his presence by attempting
to air-drop yesterday's meal on our heads. Ken Feeley, a sandy-haired
Duke graduate student and Terborgh apprentice, narrowly sidesteps
the assault. Completely frustrated and baffled by our presence,
the black-faced monkey resorts to that age-old means of escape--run,
or frantically swing, as the case may be. In a few short, orange-blurred
seconds, he darts through the trees, across a connecting land-bridge,
and disappears into the safety of a neighboring island.
After ogling the jailbreak, the rest of us slowly turn our attention
back to the trees, while Feeley stews over the implications of this
event for his dissertation research. His project, an impressive
web of hypotheses connecting everything from monkey dung to bird
densities, relies in part on the idea that the monkeys do not move
around between islands. This is normally a safe assumption, since
they live in the trees and almost never come to the ground--except,
that is, when a gang of bothersome biologists comes a-knocking.
The forest on Iguana Island is an imperfect tangle of life, a
finger-painted canvas streaked with browns and greens, a ruddy masterpiece.
A crispy carpet of leaves crunches under my feet with every step.
The scene is awash in trees, some scattered large trunks, but mostly
skinny trees and malleable lianas, spreading haphazardly in twists
and turns, arched doorways, a gnarled mass, trip wires, monkey ladders,
loops like swings, a dangling Y, an S, a C, intersections, overlaps,
no beginnings, no endings. In the thicker parts, foliage blots out
the sky above, so dense that you could tuck a pink school-bus beneath
and never find it from the air. Among the leaves on the ground stands
the occasional ant-hole, a small volcano of red dirt that spews
fat-headed ants, hungry for the surrounding green in this world
apart.
We leer, peer, and downright gawk at numerous trees, trying to
identify them for Feeley's project. Here in the deep wild of Venezuela,
there are no glossy field guides to consult, forcing scientists
to rely on more unconventional, yet equally effective techniques.
Approaching one particularly troublesome tree, Terborgh unveils
a thick knife and shaves off a piece of bark. Leaning forward, he
presses his face against the fresh white wound. Taking a deep breath
of the tree's sweet smell, he concludes that it is Guatteria schomburgkiana,
apparently not only part of the Annonaceae family, but also of the
scratch-and-sniff family as well.
Hiking the short distance to the other end of the island, Terborgh
again comments on the landscape around us: "Have you ever seen
a place this trashed before? And humans didn't even do it. Usually
it's bulldozers that do stuff like this, but this is ants and monkeys
and other things." We don't usually think of an ant as the
king of the jungle, but here on the small Lake Guri islands, this
six-legged beast rules. In fact, it is mostly leaf-cutter ants that
are responsible for the barren state of islands like Chiguire.
Here in Guri, the health of the island depends largely on its
size. On larger islands and the mainland, a wide variety of predatory
and large-sized animals thrive. Some are familiar, like the jaguar,
puma, predatory birds, and wild cats, and others strange and unfamiliar,
like the agouti, the tayra, the tapir, and the coati-mundi. But
the smaller islands are unable to sustain these large-bodied animals.
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| Although
the scope of the research in Lake Guri is obviously quite large,
my field work consisted, quite literally, of hugging trees. |
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Without vertebrate predators and seed-dispersing animals, the small
islands have experienced population explosions of certain herbivores,
creating a glut of lizards, rats, iguanas, and leaf-cutter ants.
In addition, howler monkeys stranded on the small islands when the
lake was created have lived on them predator-free for many years.
This over-abundance of herbivores is having devastating effects
on the island vegetation, stripping the trees bare. Such an avalanche
of ecological dysfunction is called a "trophic cascade,"
or alternatively, Terborgh's more dramatic term, "ecological
meltdown."
While the scope of the research in Lake Guri is obviously quite
large, my field work consisted, quite literally, of hugging trees.
Armed with a tape measure, some maps and a tool-belt, I worked on
several islands measuring the diameter of adult trees that had been
initially measured five years ago. The purpose of this work was
to quantify scientifically the vegetation damage that was clearly
visible all around us.
My mentor for this task was a garrulous Peruvian, Percy Nuñez,
who works as a kind of freelance botanist, dabbling in eco-tourism
here, writing field guides there. Known for his "hands of silk,"
he has a broad, padded face with wings of black hair that protrude
from his baseball cap. Though he is nearly forty, his smile flashes
a mouth full of braces. He speaks with a kind of wise serenity,
and whenever I asked him a question, he rubbed his thick hand over
his face, as if waking up the cells in his brain to think a little
harder. Nuñez is one of the world's most knowledgeable tropical
botanists, and has seen 10,000 different tree species in his career.
He even has discovered and helped describe ten new species, including
his favorite plant of all, Styrax nunezii (named for him).
Although the awkwardness of my last name may preclude the honor
of ever having a species named after me--Balukjianii does not exactly
roll off the tongue--I look forward to a career of discovery among
the world of islands. I have been an "islephile" ever
since the mullet-haired days of elementary school, when I pored
over maps dotted with islands and declared that in my lifetime,
I would visit every island in the world.
Islands have always captured people's imaginations, not only for
their physical beauty but also for their symbolism as a secluded
entity. Sir Thomas More saw water on all sides around him when he
sketched out his vision of Utopia. And while poet John Donne declared
that "no man is an island," we are time and again lured
into the isolation afforded by islands' simple pleasures.
No matter where I drift, I hope never to stray far from the world
of islands, those self-contained little worlds isolated from the
smear of civilization. Island biogeography is my own self-designed
curriculum, put together under the auspices of Duke's Program II,
which provides students the opportunity to design an interdisciplinary
curriculum without being limited to one of the conventional majors.
That opportunity is what brought me to this team, and to Lake Guri.
Today's islands are often associated with white beaches and resort
hotels; life on Lake Guri was not so glamorous. Our research team
was divided between two camps, one on the large island Danto Machado
and the other on Iguana Island, so tiny that John Elway could probably
heave a football over half its length. The only permanent structure
in either camp was a small shelter made of logs spaced far apart
and held together by wire. A plastic tarp draped over the top of
the shelter kept us dry during the torrential rains.
Words like "clean" take on a whole new meaning when
you live in a tent for two months on an island where there is no
running water, no electricity, no buildings, and, of course, no
toilets. Food was simple, cooked over either a campfire or a gas
stove, and inevitably consisted of some combination involving sauce
and beans, rice or pasta. Every day after working in the field,
we bathed in the murky lake water, jumping off trees in the ghost
forest and withstanding the nibbles of little fish that enjoyed
snacking on our bare bodies.
Scientists shuttled in and out of the camp over the course of
the summer. They studied all sorts of things, from rats to land
tortoises to the most pungent of all study organisms, dung beetles.
Days were filled with collecting data on different islands, and
nights were spent playing cards, writing, and chatting, while rowdy
bugs flew into camp and pesky moths fluttered and flopped around
as if someone had spiked their nectar. The whole while, life teemed
around us--the horrid grunts of far-off howler monkeys in the distance
and the screeching and squawking of parrots tearing through the
air like squirrels in a china closet. The soft, continuous hum of
hidden insects was occasionally interrupted by the whirling sound
of a cicada, like an overcharged sprinkler.
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| One island's
healthy forested interior |
| photo:Brad
Balukjian |
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Many of the processes and phenomena occurring on islands reflect
those that occur on the mainland. But the isolation of islands has
produced some pretty wacky results. Only certain intrepid species
are able to colonize isolated islands (e.g., Hawaii), and once there
they may remain separated from their native population for several
generations. The isolation allows organisms to evolve into the outlandish
and the bizarre, producing such fanciful creatures as Komodo dragons
and the giant tortoises of the Galapagos. These are the island eye-catchers
that any channel-surfer recognizes from brief flashes on the Discovery
Channel. Although not as stunning, the leaf-cutter ants and howler
monkeys of Lake Guri proved to be just as interesting.
The leaf-cutter ants are particularly effective in defoliating
the small islands. While doing my field work one day, I saw a parade
of leaf fragments dancing in a nice orderly line down the forest
floor. An ant was underneath each leaf, clasping it tight with its
mandibles. Ants stash great gobs of foliage in underground burrows
and feed off of a fungus that grows on them.
Although things seem peachy for the ants and their vegetarian
accomplices, the island trees will not be able to withstand this
assault much longer. In the near future, we predict that a large
number of tree species will go extinct on the islands (some already
have), and that the only survivors will be snarling vines and inedible
plants loaded with chemical and physical defenses. Without any more
food, the ants, monkeys, and other herbivores are destined to crash,
leaving the island a virtually empty wasteland.
At first glance, it might seem that while this obituary-to-be
is a shame, it is at least confined to some obscure islands in the
middle of nowhere in Venezuela. The bad news is that this same phenomenon
is occurring all over the world. As our planet's natural habitats
become increasingly fragmented because of human expansion and development,
mainland landscapes are being chopped up into mosaics of "islands."
Studying the Lake Guri islands is like looking into a crystal ball
to see what looms for the rest of the world.
Balukjian is a senior from Greenville, Rhode Island.
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