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Sharks, Coral, Giant Cod, Manta Rays and
a new scientific theory
By Shawn Blore
A coral reef is like a city, Charles Darwin
once said. He meant that reefs were home
to an incredible diversity of species who
went about exchanging material - carbon,
energy; old seashells - with the same manic
intensity of urbanites trading goods and
cash. As a popular naturalist, Darwin used
simple explanations to demystify the natural
world. But even he would have been surprised
by how well his analogy worked in Calms,
Australia.
On my first day in the waters of the Great
Barrier Reef, I notice that the sea creatures
bear an eerie resemblance to those poking
around north Queensland's largest city. Scientists
have recently begun to discover the myriad
ways in which coastal cities like Calms have
affected the reef But what if the reef were
also changing Calms?
It's an insight that hits me in a minor "Eureka!"
moment as I glide through the clear water
of Harrier Reef, stopping to peer beneath
a veranda-sized overhang of plate coral.
The half-dozen coral groupers - big, meaty
fish from the Serranidae family - waiting
out the midday heat bear an uncanny resemblance
to the lads with bush hats and sleeveless
shirts ("rough as guts" in the
local vernacular) that I'd found knocking
back midday pints in a hotel bar in Cairns.
Both species have the wary stare of creatures
not quite far enough up the food chain. And
though neither species is exactly verbal,
both manage to convey that they'd prefer
it if I'd just move along.
Coincidence, perhaps, but just after I fin
away from the groupers I come across a school
of goldback anthias soaring in the upwelling
atop a coral ridge. They're all identical
and exquisitely beautiflul: small purple
fish with a gold stripe down the back and
little gold flecks around the cheeks and
eyes. When I kick over to make friends, the
anthias flit nervously out of reach and regroup
again further away. It was the same sequence
I'd seen two nights earlier in Cairns, when
a pair of sunburnt Brits had tested their
cockney charm on a tour group of Japanese
girls - all beautiful, their clothes, makeup
and demeanour seemingly identical. When the
Brits approached, the tour group split in
two, flowed round the amorous cockneys and
re-formed again a little further away.
Surely I was on to something. If confirmed,
my theory would be the kind of breakthrough
that could land me on the cover of Science.
Alas, that very evening my original hypothesis
met up, in the words of Darwin's friend and
colleague Thomas Huxley, with a "single
ugly fact." A 400-some-kilo fact, with
bulbous eyes, a protruding lower jaw and
nostril cavities you could hide your fist
in. Epinepheleus tuka, the potato cod, is
about as attractive as a schoolyard geek
on steroids.
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The dive master had repeatedly lectured us
not to blind the wildlife with our flashlights.
But when I saw a shadow beneath me brought
my beam up and fixed that giant cod right
between the eyes. Seconds later it slammed
headfirst into a coral wall.
My eco-guilt was made worse when
the cod
pulled back and it looked like
its tail was
coming out its mouth. But no,
the tail belonged
to a parrot fish. It had probably
been asleep
in the coral when the cod dived
in. Half-devoured,
it managed a last little tail
wiggle, then
the cod gulped, and the parrot
fish was gone,
swallowed up along with my theory.
of course,
no one in laidback, tropical
Calms would
roust you out of bed only to
swallow you
whole. My future in science was
fading fast.
Fortunately, there was an accredited
scientist
accompanying the 17 passengers
and seven
crew on board the Undersea Explorer.
Indeed,
the five-year-old company was
set up to bring
divers and researchers together.
Scientists
on the Undersea Explorer share
their knowledge
with the tourists in return for
free use
of the boat as a research platform.
On shark-research
trips, passengers get to help
out with shark
tagging. When the whale scientists
come aboard,
the Explorer heads north to seek
out minkes.
During the spring, the boat travels
to the
unexplored northern section of
the reef in
search of whale sharks and manta
rays. Springtime
trips are also a chance to witness
the world's
largest orgy as the hundreds
of millions
of coral animals that make up
the more than
2,000-kilometre-long Great Barrier
Reef all
pawn on a single moonless night
in mid-November |
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Dr. Pat Hutchings' passion is boring worms.
Literally. She studies he hundreds of species
of marine worms that bore or scrape out homes
in both the top layer of living coral and
in the lower layers of dead coral (the substrate)
that serve as the reef's foundation. A researcher
at the Australian Museum in Sydney, Dr. Hutchings
also as a soft spot for parrot fish, the
coral grazers that scrape and munch off bits
of living coral with their powerful beak-like
teeth. On a healthy reef, all this boring
and scraping and munching - bioerosion in
scientific parlance - is balanced by living
coral colonies hat lay down new layers of
reef substrate as they grow. Unfortunately,
healthy reefs are becoming less and less
common. |
About 10 percent of the world's reefs
have
been destroyed; another 30 percent
are threatened.
In industrialized countries the major
culprits
include housing developments and the
toxic
runoff from agriculture. South Florida's
reefs may have less than a decade to
live,
thanks to wall-to-wall beachfront condos
and intensive sugar production. Things
are
less dire Down Under, but reef health
.s
still a major concern.
Dr. Hutchings' contribution to preservation
efforts is an investigation into bio-erosion
rates off the north Queensland coast.
Three
years ago, she sailed out on the Explorer
and bolted small bricks of coral substrate
onto the reef at various sites, including
Osprey Reef in the middle of the Coral
Sea,
200 kilometres from the mainland. Over
time,
the munching and boring erode the blocks,
while live corals recolonize them and
lay
down new layers of reef material. Once
the
coral blocks are taken back to the
lab and
weighed, the net change in block mass
gives
a concrete measure of the rate of bio-erosion.
Its an important, long-term method
for measuring
reef health. But here at Osprey Reef,
I'm
in the mood for something more stimulating
than coral blocks and boring worms.
So while
Hutchings swims off with a collecting
bag
clutched in her hands, I set out to
do a
bit of exploring.
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