Hạ Long Bay has a very complicated
structure with its meandering
coastline and many river mouths.
Rich and diversified sources of food
for many species of plants and
animals are also found here. In
particular, the bay, partitioned by
thousands of large and small
islands, creates areas of water with
an average and stable sea level.
Meanwhile, the climate in Hạ Long
Bay is also very stable, with an
average temperature of between 19
and 25ºC, and an average heat
radiation rate of 17 kcal/ sq. cm/
month. It sees an average rainfall
of 2,000 to 2,200 mm/ year. These
favourable conditions have seen the
development of many varied
ecosystems.
Results of scientific research show
that Hạ Long Bay features ecosystems
of a tropical ocean region, such as:
salt water-flooded forests, coral
reefs and tropical rain forests.
In the sea surrounding Hạ Long,
coral grows in many places, but is
densely concentrated on the eastern
and southern sides, far from the
mainland. According to research
conducted by scientists from the
Oceanographic Institute, Hạ Long Bay
is home to 163 species of coral,
from 44 lines of descent and 12
families. Coral reefs are
distributed everywhere, generally at
a depth of 4 to 6m. The coverage
rate of coral reef is 30% on
average, but there are areas where
it attains 70 to 80%, such as at
Cống Ðỏ and Bọ Hung. The coral
forests of Hạ Long Bay are a
wonderful sight, with many
extraordinary shapes and diversified
colours. When the tide flows, the
coral moves with the water, pumping
as rhythmically as a heartbeat. At
the same time, the reefs are
residence to a great number of
species: fish (107 varieties), water
plants, algae and transitory animals
and plants.
The salt water-flooded forests also
offer especially interesting scenery
along the coastline of Hạ Long Bay.
These forests are chiefly
concentrated in the zones of Tuần
Châu, Cửa Lục and Ba Chẽ. Many
species of salt water-flooded
plants, the most diversified
collection in North Vietnam, are
found here. Also living in these
flooded forests are a great many
species of animals: migrating birds
(37 species), sea-bottom animals (81
species) and fish (90 species
belonging to 55 families). In
particular, bottom-feeders account
for 61% of the total species in the
whole tidal region, with many
species being of great economic
value: arcae, meretrixes and all
kinds of crustaceans.
The tropical rain forest ecosystem
also features a rich quantity of
species: đinh, hương, sến, táu
trees. This is the residence of
various rare and precious creatures:
deer, weasels, squirrels and in
particular, white-tabby and
red-haired monkeys.
At the same time, there is a system
of small caves along the sea, which
are the living and development
places for many animals and plants:
seaweed, water plants, algae, fish
and shrimp. Deeper into the water,
there are also many species of
shrimp, fish (almost 1,000 species),
abalone and other sea-specialities;
harvested every year to the tune of
several thousand tons.
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