Seychelles PHYSICAL ENVIRONMENT
Fisherman holding hawksbill turtle, Aldabra Islands; shell is used
to make tortoiseshell objects.
Courtesy Brian Kensley
Giant land tortoises, Aldabra Islands
Courtesy Brian Kensley
The archipelago consists of 115 islands and thirty
prominent
rock formations scattered throughout a self-proclaimed
exclusive
economic zone
(EEZ--see Glossary)
of more than 1.35 million
square kilometers of ocean
(see Seychelles -
fig. 7). Some forty
islands are
granitic and lie in a ninety-kilometer radius from Mahé,
the main
island. The remaining islands are coralline, stretching
over a
1,200-kilometer radius from Île aux Vaches in the
northeast to
the Aldabra Atoll in the southwest. The islands are all
small--
the aggregate land area is only 444 square kilometers,
about twoand -a-half times the size of Washington, D.C.
Mahé is twenty-five kilometers long and no more than
eight
kilometers wide. It contains the capital and only city,
Victoria,
an excellent port. Victoria lies approximately 1,600
kilometers
east of Mombasa, Kenya; 2,800 kilometers southwest of
Bombay;
1,700 kilometers north of Mauritius; and 920 kilometers
northeast
of Madagascar. The only other important islands by virtue
of
their size and population are Praslin and La Digue,
situated
about thirty kilometers to the northeast of Mahé.
The granitic islands are the peaks of the submarine
Mascarene
Plateau, a continental formation theorized to be either a
part of
Africa separated when Asia began to drift away from the
original
single continent of Gondwanaland, or the remnants of a
microcontinent that existed up to the beginning of the
Tertiary
Period, approximately 50 million years ago. The granitic
islands
are characterized by boulder-covered hills and mountains
as high
as 940 meters rising abruptly from the sea. Elsewhere,
narrow
coastal plains extend to the base of the foothills.
Extensively
developed coral reefs are found mainly on the east coasts
because
of the southwest trade winds and equatorial current.
Ninety-nine
percent of the population is located on the granitic
islands, and
most are on Mahé.
The coralline islands differ sharply from the granitic
in
that they are very flat, often rising only a few feet
above sea
level. They have no fresh water, and very few have a
resident
population. Many, like Île aux Vaches, Île Denis, the
Amirante
Isles, Platte Island, and Coetivy Island are sand cays
upon which
extensive coconut plantations have been established. Some
of the
coralline islands consist of uplifted reefs and atolls
covered
with stunted vegetation. Several of these islands have
been
important breeding grounds for turtles and birds, as well
as the
sites of extensive guano deposits, which formerly
constituted an
important element of the Seychellois economy but now for
the most
part are depleted. Aldabra Islands, the largest coralline
atoll
with an area greater than Mahé, is a sanctuary for rare
animals
and birds.
The uniqueness of the Seychelles' ecology is reflected
in the
US$1.8 million project of the Global Environment Trust
Fund of
the
World Bank (see Glossary)
entitled Biodiversity
Conservation
and Marine Pollution Abatement, that began in 1993. The
World
Bank study for this project states that the islands
contain, out
of a total of 1,170 flowering plants, "at least
seventy-five
species of flowering plants, fifteen of birds, three of
mammals,
thirty of reptiles and amphibians, and several hundred
species of
snails, insects, spiders and other invertebrates" found
nowhere
else. In addition, the waters contain more than 900 kinds
of
fish, of which more than one-third are associated with
coral
reefs. Specific examples of unique birds are the black
paradise
flycatcher, the black parrot, the brush warbler, and a
flightless
rail.
As a result of extensive shipping to Seychelles that
brings
needed imports and the discharge of commercial tuna
fishing, the
waters are becoming polluted. Furthermore, goats brought
to
Aldabra Islands are destroying much of the vegetation on
which
giant turtles, including two species unique to
Seychelles--the
green and the hawksbill--feed or seek shade.
Seychelles began addressing the conservation problem in
the
late 1960s by creating the Nature Conservancy Commission,
later
renamed the Seychelles National Environment Commission. A
system
of national parks and animal preserves covering 42 percent
of the
land area and about 26,000 hectares of the surrounding
water
areas has been set aside. Legislation protects wildlife
and bans
various destructive practices. In Seychelles' 1990-94
National
Development Plan, an effort was made to include in the
appropriate economic sectors of the development plan
environment
and natural resources management aspects.
Also connected with ecology is a World Bank project
dealing
with the environment and transportation. Launched in 1993
with a
loan of US$4.5 million, it is designed to improve the
infrastructure of Seychelles with regard to roads and
airports or
airstrips so as to encourage tourism as a source of
income, while
simultaneously supporting environmental programs in
resource
management, conservation, and the elimination of
pollution.
The climate of Seychelles is tropical, having little
seasonal
variation. Temperatures on Mahé rarely rise above 29 C.
or drop
below 24 C. Humidity is high, but its enervating effect
is
usually ameliorated by prevailing winds. The southeast
monsoon
from late May to September brings cooler weather, and the
northwest monsoon from March to May, warmer weather. High
winds
are rare inasmuch as most islands lie outside the Indian
Ocean
cyclone belt; Mahé suffered the only such storm in its
recorded
history in 1862. Mean annual rainfall in Mahé averages
2,880
millimeters at sea level and as high as 3,550 millimeters
on the
mountain slopes. Precipitation is somewhat less on the
other
islands, averaging as low as 500 millimeters per year on
the
southernmost coral islands. Because catchment provides
most
sources of water in Seychelles, yearly variations in
rainfall or
even brief periods of drought can produce water shortages.
Small
dams have been built on Mahé since 1969 in an effort to
guarantee
a reliable water supply, but drought can still be a
problem on
Mahé and particularly on La Digue.
Data as of August 1994
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