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FALL 2016
LIFE AQUATIC
MARINE BIOGEOGRAPHY
unexso @unexsobahamas
fish or invertebrate might evolve
into two or more species over time.
As sea levels rise and land barriers
are once again covered with water,
expanding marine habitats allow
the now genetically dissimilar
populations to mix again. Thus,
climatic events in combination with
tectonic movements have caused
previously isolated species to
evolve, congregate in and disperse
from the Coral Triangle.
HABITATS AND NICHES
Geography, climate, plate tectonics,
recurring ice ages and oceanic
current circulation play large roles
in species’ aggregation in and
dispersal from given regions, but
another vital factor in determining
a place’s biomass and biodiversity
is the number of habitats and
niches available. The more habitats
and niches, the more species an
area will have. For example, the
cold, coastal waters of Cape Cod,
Mass., offer few habitat differences,
while the seascape among the
islands of Indonesia offers many.
Flooded by daily tides, extensive
mangrove forests support juvenile
fishes. Seagrass meadows also act
as nurseries for a large number of
reef dwellers. Nearby lagoons offer
protected patch reefs as habitats
for large reef fishes. The three-
dimensional, honeycomb structure of
barrier reefs adds even more niches.
VARIETY, NOVELTY
AND ADVENTURE
Marine biogeography — the
wild array and distribution of
underwater life — is a vital
ingredient in making recreational
diving the adventure that it is. Each
time divers venture beneath the
surface, no matter where in the
world, they have the opportunity
to observe a creature, a behavior or
a relationship that they never seen
— and perhaps one that no one
has ever seen. It is now estimated
that there are roughly 8.7 million
species on Earth. Somewhere
between 35,000 and 60,000 reef
dwellers have been described
to science, including many, but
certainly not all, shallow-water
fish and invertebrates. At present,
about 76 percent of the world’s
coral species and 37 percent of
all reef fishes, an estimated 3,000
species in all, flourish within the
Coral Triangle. Beyond simply
keeping divers fascinated, this
biodiversity is a vital cog in the
interconnected ecosystems of
planet Earth. Every species and
individual plays a role, and humans
cannot separate themselves from
this interconnectedness.
“Our understanding of the origin
of diversity and distributional
patterns in the Indo-West Pacific is
still rudimentary,” Paulay said. So far
it has been impossible to unravel the
mysteries and explain all the reasons
underlying coral reef life. Besides
a handful of well-studied fish and
invertebrates, most coral reef
dwellers are not well understood
because of the difficulties in
studying them. It is clear no single
explanation for the distribution of
plants and animals will suffice — a
variety of complicated processes are
at work, and they create a plethora
of unique diving situations around
the world.
One of the most captivating
aspects of this planet is that life,
which is constantly and continually
evolving, is unevenly distributed.
The observable variability of species
that inhabit each diving destination
is what drives recreational diving
around the world. It’s a big part of
what keeps divers enduring long
travels across the globe — the will
to be in the midst of flourishing
and ever-evolving life, discovering
just a bit more about the unknown,
no matter how far we must go.
AD