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How
the type of atoll affects the fish
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The fish communities inhabiting
the atolls are highly complex. They are subject to
interactions between
large-scale factors such as bio-geographical
factors, the type and size of atoll and the
proximity between the islands, and local factors
such as the biotope, the depth of the waters, the
exposure of the atoll to the wind, the effects of
fishing and the degree of aperture of the atoll
lagoons to the open sea. |
The regional factors contribute
importantly to determining the overall size of an atoll
community, since the diversity of the fish species
depends on the size of the atoll, just as it determines
in turn the density,
the biomass and the productivity of the fish community.
The smaller the atoll, the more fragile the fish
communities inhabiting it will be. Fishing activities
usually take their toll of the most fragile species (the
fish-eaters, macro-carnivores and macro-herbivores) and
those which require the most vital space. It is
therefore recommended to keep the fishing activities
around the smaller atolls to a minim.
The output of the atoll fish communities probably
consists largely of plankton-eaters and
micro-herbivores. The consistency of this output
over time probably depends on the size of atoll and its
degree of aperture to the surrounding ocean. The larger
these two parameters are, the more stable the output at
a given atoll will be.
Generally speaking, the fish communities inhabiting the
French Polynesian atolls show a wide range of diversity,
but less so than their West Pacific counterparts,
because of the bio-geographical differences involved.
The Polynesian atolls are also probably more sensitive
to disturbances than the
West Pacific atolls, precisely because of this
relative lack of diversity.
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