Chic, petite and classically contoured but the good looks of the
chambered nautilus belie a powerful past where it grew up to two metres
in diameter and ruled the oceans as one of the world's greatest marine
predators.
Four hundred million years later and the nautilus have been reduced to a
size of around 150 millimetres and living in a handful of deep dark
coral reefs around the Indo-Pacific region. Each night they rise from
the depths of the ocean to feed quietly, unseen by the apex predators of
today such as sharks and strong jawed fishes.
Unlocking the evolutionary dynamics of the nautilus is the work of
scientists on board Australia's Undersea Explorer - a combined adventure
dive and research vessel.
At Osprey Reef, a remote outer section of the Great Barrier Reef, marine
biologist Andy Dunstan uses deep water trapping, tagging and release
techniques to identify the sex, age, home range, population, feeding
behaviour, growth rates and juvenile habitat of Nautilus pompilius.
|
"The nautilus of Osprey Reef spend their whole life cycle there," says
Andy. "They are 'imprisoned' by the 1500 metre deep surrounding waters
and their lack of a larval dispersal phase. So far, our recapture data
indicates a population of approximately 7,500 in the immediate area."
"The beauty of the nautilus shell makes them popular with collectors but
our findings suggest their late sexual maturity and low numbers of
offspring make them vulnerable to overfishing."
Andy's continued research will be used to propose sustainable management
strategies for nautilus fishing. For more information on the nautilus
and how Undersea Explorer channels the support of adventure divers into
marine exploration and conservation, see
www.undersea.com.au
|
