Travel Reference
In-Depth Information
spread their heavy nets in the river's shallows. They waited patiently, then
hauled in the nets to yield a sparse handful of wriggling small sardine-like
fi sh. The Irrawaddy once teemed with fi sh, but dam-building and overfi shing
have emptied the river.
The industrialization of Myanmar has been suppressed by its current gov-
ernment, a cruel and ignorant collection of generals and their greedy relatives.
Ironically, this may be the temporary salvation of the teeming reefs of the Mer-
gui Archipelago. By the time the agricultural runof reaches the Mergui islands,
hundreds of miles from the Irrawady's multiple mouths, it is capable of nour-
ishing a wide variety of plankton. More intensive agriculture and industry will
inevitably result in a witches' brew of nitrogen-rich runof mixed with indus-
trial waste that will certainly disturb this balance in the future.
A voyage through the Mergui islands today reveals a wonderfully rich
but fragile ecosystem. Invisible to the casual visitor, it is immediately appar-
ent to anyone who ventures beneath the ocean's surface. Because of the great
clouds of plankton nourished by the river, there is plenty of room for many
species of animals and plants to carve out specialist ways of feeding and
establishing territories.
But a rich fl ow of plankton is not enough to explain such diversity. Eco-
systems in the Arctic and Antarctic are rich in plankton but support far fewer
species than the Mergui Archipelago. To support diversity throughout the
food chain the plankton themselves must be diverse, providing a wide vari-
ety of potential food sources and their associated nested ecological niches. In
Mergui this diversity is supported by ample solar energy and inorganic nutri-
ents. In the next chapter we will see how, even at the level of the single-celled
plankton on which the rest of the food chain depends, ecological and evolu-
tionary forces have combined to produce and maintain a diversity of species.
Ecological niches
A principle of ecology that was fi rst proposed early in the twentieth cen-
tury states that two species cannot occupy the same ecological niche at the
same time. This
niche-exclusion principle
has been supported by simple labora-
