Environmental Engineering Reference
In-Depth Information
x
the world's known plant species. However, they con-
tain only about 3% of the world's rare and threatened
plant species.
Botanical gardens also help educate an estimated
150 million visitors each year about the need for plant
conservation. But these sanctuaries have too little stor-
age capacity and too little funding to preserve most of
the world's rare and threatened plants.
We can take pressure off some endangered or
threatened species by raising individuals on farms for
commercial sale. For example, farms in Florida raise
alligators for their meat and hides. Butterfly farms
flourish in Papua New Guinea, where many butterfly
species are threatened by development activities.
H OW W OULD Y OU V OTE ? Should the Endangered Species
Act be modified to protect the nation's overall biodiversity?
Cast your vote online at http://www.biology.brookscole
.com/miller11.
9-5 PROTECTING WILD SPECIES:
THE SANCTUARY APPROACH
Science and Stewardshp: Wildlife Refuges and
Other Protected Areas
The United States has set aside 542 federal
refuges for wildlife, but many refuges are suffering
from environmental degradation.
In 1903, President Theodore Roosevelt established the
first U.S. federal wildlife refuge at Pelican Island,
Florida. Since then, the National Wildlife Refuge
System has grown to include 542 refuges. More than
35 million Americans visit these refuges each year to
hunt, fish, hike, or watch birds and other wildlife.
More than three-fourths of the refuges serve as vi-
tal wetland sanctuaries for protecting migratory wa-
terfowl. One-fifth of U.S. endangered and threatened
species have habitats in the refuge system, and some
refuges have been set aside for specific endangered
species. These areas have helped Florida's key deer,
the brown pelican, and the trumpeter swan to recover.
Conservation biologists call for setting aside more
refuges for endangered plants. They also urge Con-
gress and state legislatures to allow abandoned mili-
tary lands that contain significant wildlife habitat to
become national or state wildlife refuges. Bad news: Ac-
cording to a General Accounting Office study, activi-
ties considered harmful to wildlife occur in nearly 60%
of the nation's wildlife refuges.
Science and Stewardshp: Zoos
and Aquariums
Zoos and aquariums can help protect endangered
animal species, but efforts lack funding and storage
space.
Zoos, aquariums, game parks, and animal research cen-
ters are being used to preserve some individuals of crit-
ically endangered animal species, with the long-term
goal of reintroducing the species into protected wild
habitats.
Two techniques for preserving endangered terres-
trial species are egg pulling and captive breeding. Egg
pulling involves collecting wild eggs laid by critically
endangered bird species and then hatching them in
zoos or research centers. In captive breeding, some or all
of the wild individuals of a critically endangered
species are captured for breeding in captivity, with the
aim of reintroducing the offspring into the wild, such
as with the peregrine falcon and the California condor
(Figure 9-3).
Lack of space and money limits efforts to maintain
populations of endangered species in zoos and re-
search centers. The captive population of each species
must number 100-500 individuals to avoid extinction
through accident, disease, or loss of genetic diversity
through inbreeding. Recent genetic research indicates
that 10,000 or more individuals are needed for an en-
dangered species to maintain its capacity for biological
evolution.
Zoos and research centers contain only about 3%
of the world's rare and threatened plant species. The
major conservation role of these facilities will be to help
educate the public about the ecological importance of
the species they display and the need to protect their
habitat.
Public aquariums that exhibit unusual and attrac-
tive fish and some marine animals such as seals and
dolphins also help educate the public about the need
to protect such species. In the United States, more than
35 million people visit aquariums each year. Public
Science and Stewardshp: Gene Banks,
Botanical Gardens, and Farms
Establishing gene banks and botanical gardens,
and using farms to raise threatened species can
help protect species from extinction, but these
options lack funding and storage space.
Gene or seed banks preserve genetic information and en-
dangered plant species by storing their seeds in refrig-
erated, low-humidity environments. More than 100
seed banks around the world collectively hold about 3
million samples.
Scientists urge the establishment of many more
such banks, especially in developing countries. Unfor-
tunately, some species cannot be preserved in gene
banks. The banks are also expensive to operate and
can be destroyed by accidents.
The world's 1,600 botanical gardens and arboreta
contain living plants, representing almost one-third of
Search WWH ::




Custom Search