Biology Newsletter - The University of Sydney

RESEARCH SPOTLIGHT:
WILLIAM FIGUEIRA
The events in Finding Nemo might seem
farfetched, but tropical fish do indeed travel
the East Australian Current to be found as far
as Sydney. Dr William (Will) Figueira studies
the movement of these tropical fish and
their potential to survive the winter in the
temperate zone.
“They typically die over the winter,” said
Will, explaining fate of the tropical fish
that make it to Sydney. “We look at the
mechanisms that kill them off as a way
of understanding when they’ll be able
to survive.”
A fish species’ distribution depends
on a number of environmental
and biological factors, including
temperature. “I look at benthic fish,
which stay in a particular area for
most of their lives. These are the ones
whose geographic distribution may
creep over time as a result of changing
climate and warming oceans.”
To study the tropical fish that venture
into temperature waters, Will has the
enviable task of swimming the waters
up and down the East Coast. “We do
lots of observational stuff - snorkelling,
diving and counting.” Along with David
Booth’s team at UTS, Will conducts
regular surveys around Sydney,
Merimbula and at other locations.
Data from these sites has been
collected since 2002. This long-term
monitoring enables them to look at the
consistency of tropical fish settlement
patterns from year to year.
But not all tropic fish species are found
south each summer. So which tropical
fish, and in what numbers, have been
appearing in temperate waters? “We’ve
had a paper recently with David Feary
at UTS looking at the characteristics of
the tropical fish we see here, relative to
the ones we don’t see. We asked the
question, what are the traits of animals
that disperse?”
Fishy physiology plays a role. It is not
fixed, as Will explained, “they have the
ability to adapt, either plastically within
a generation or evolutionarily through
multiple generations. That adaption
will change the speed of the range
expansion.”
Field-work - flying out to the reef
“To understand the fish’s tolerance
limits and acclimation ability, we take
them into the lab and look at how they
grow, how they swim, etc, when they
are held at different temperatures.”
Will’s group also uses computer
modelling to understand the range
expansion of tropical fish. “I’ve done a
fair amount of biophysical connectivity
modelling to understand how habitats
are connected by organisms.” He uses
oceanographic flow data and output
from models to simulate the movement
of the fish larvae. “The quality of the
modelling all comes down to how well
you understand how the larvae behave,
how they can swim, how they can
sense things, etc. My new PhD student
Steve Hawes is working on these
connectivity models.”
However range expansion is not a
concept that is restricted to tropical
fish. “Temperate fish and invertebrates
are also heading south and being found
in greater numbers in Tasmania.” Will’s
work may therefore be applicable
across latitudes, with the potential to
use the presence of these ‘vagrant’
fish as an index for climate change.
“We have funding to collect data all
along the coast at intensive temporal
and spatial resolutions. Once the data
has been analysed we will know how
often you need to sample in order to
say ‘the vagrant fish are becoming
more abundant’ and to link it to climate
change”.
So finding Nemo in Sydney Harbour
will become a common occurrence.
And Will’s research will be able to
tell us when to expect the clownfish
population to survive year-round.
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