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 ammals, fish, birds, amphibians, and reptiles
the higher ani mals known collectively as vertebrates are suffering high
rates of decline, reports a new study from the Worldwatch Institute. About
one in four vertebrate species surveyed so far is in serious trouble - either
declining sharply in numbers, limited to dangerously small populations,
or facing pressure from land clearance, road building, excessive hunting
and fishing, and other human activities.
 "We are in the midst of a mass
extinction, an event not seen since the disappearance of the dinosaurs 65
million years ago," says John Tuxill, a Research Fellow at the Worldwatch
Institute and author of Losing Strands in the Web of Life: Vertebrate
Declines and the Conservation of Biological Diversity. "But unlike
the dinosaurs, we are not just contemporaries of a mass extinction we are
the reason for it."
In 1996, the World Conservation Union
(IUCN), in collaboration with over 600 scientists, published a groundbreaking
survey of the status of animal life on Earth. According to their estimates,
25 percent of mammal and amphibian species, 11 percent of birds, 20 percent
of reptiles, and 34 percent of fish species surveyed so far are threatened
with extinction. In addition, another 5 to 14 percent of species in these
groups are "nearing threatened status."
"The declining health of vertebrates
is but one indicator of a decline in many facets of the natural world,"
said Tuxill. "Plants, insects, snails, and many other organisms are
also threatened. Together, all of these life forms make up what scientists
call biodiversity the rich diversity of life that underpins everything from
food production to a host of essential medicines. Unlike other environmental
losses, this one cannot be reversed. With biodiversity, nature doesn't give
second chances."
"Even as we begin to appreciate
the vast array of goods and services that diverse natural systems provide,
most of what we are losing is still a mystery," Tuxill concluded. "We
have barely begun to decipher the ecological relationships that keep natural
systems running smoothly. If the IUCN's findings are updated regularly,
and become as widely discussed as inflation or unemployment rates, we will
have a powerful gauge for measuring the damage we are doing to natural systems."
Scientists estimate that extinction
rates are now 100 to 1,000 times greater than normal and rising sharply.
Since most species are unknown and unmonitored, the relatively well-studied
vertebrates offer one of the best windows on why and how species are declining.
The leading cause of vertebrate declines
is human destruction of old growth forests, wetlands, chaparral, and other
rich habitats. Worldwide, over two-thirds of the earth's habitable land
surface has been significantly disturbed by human activities. Nearly half
of the world's 233 primate species are threatened, largely because of their
dependence on large expanses of tropical forest, a habitat under siege around
the globe. In hot spots of forest loss, such as Madagascar, the Atlantic
rainforest of eastern Brazil, and Southeast Asia, roughly 70 percent of
primate species face extinction.
Habitat alteration is less visible
but equally severe underwater. 40,000 large dams and hundreds of thousands
of smaller barriers plug up the world's rivers, altering water temperatures,
seasonal flow patterns and other conditions that support fish. In the heavily
altered Colorado River basin, 29 of 50 native fish species are either extinct
or endangered. And 30 percent of the world's coral reefs which support the
oceans' greatest concentrations of biological diversity are in critical
condition from pollution, sedimentation, and destructive fishing and mining.
Tuxill also reports on over-hunting
and over-fishing, the main dangers facing about one-fifth of all threatened
species surveyed-propelled largely by commercial markets for wildlife meat,
hides, and other products. Of particular concern are the unregulated "bushmeat"
trade in Central and West Africa, and East Asian demand for medicinal products
derived from animals. Some 36 sea horse species are threatened by the trade
of an estimated 20 million sea horses each year for use in traditional Chinese
medicines, in the aquarium trade and as tourist curios. Large mammals, reptiles,
and fish are especially vulnerable to over-hunting a worrisome trend since
these creatures have equally outsized ecological roles. In Central Africa,
certain trees that rely on elephants to disperse their seeds failed to regenerate
normally after elephant populations crashed from over-hunting.
An additional problem is the help,
intentional and unintentional, that humanity gives to invasive species highly
adaptable animals and plants which "hitchhike" with humankind
to locations and ecosystems outside their native ranges. Invasive species
are particularly devastating on islands and in isolated lakes and rivers,
where native species are often unprepared to face exotic competitors.
The study examines a number of possible
routes for reversing these mounting species declines. Tuxill points to promising
strategies for conserving biodiversity in countries as diverse as Zambia,
Nepal, and the United States, and calls for expanded steps at every level
to manage the environment in more ecologically sound and socially equitable
ways.
Governments have attempted to stem
habitat loss by establishing national parks and wildlife refuges. Despite
some notable successes, such networks of protected areas cannot by themselves
save most species. At the national level, countries need to strengthen existing
institutions like endangered species programs, and make the management of
protected areas more collaborative, especially in cases where local residents
have traditions of wisely managing natural resources. It is also essential
to strengthen international laws and agreements for protecting biodiversity,
like the Convention on Biological Diversity (which the United States has
yet to ratify).
No system of laws or parks can ultimately
protect the world's animals unless the underlying forces driving their destruction
are contained. Stabilizing the world's population, reducing overconsumption
by the world's middle and upper classes, and meeting the basic needs of
billions of poor people are essential for maintaining and restoring the
world's biological health.
"Either we redouble our efforts
to protect species and reverse the problems degrading natural communities,
or we will be left with depleted, far simpler ecological systems that no
longer provide the material, aesthetic, and spiritual benefits we have long
taken for granted," said Tuxill. "We still have the choice of
saving most species-but our children may not."  |
worldwatch.org; website www.worldwatch.org