Fish
populations
on
reefs
separated
by
hundreds
of
kilometres
show
synchronised
population
changes,
they
can
boom
or
bust
simultaneously
due to
effects
of
climate
fluctuations.
Research
along
the
length
of the
Great
Barrier
Reef
over
13
years
by
ecologists
at the
Australian
Institute
of
Marine
Science
(AIMS)
has
shown
the
synchronizing
effects
of
climate
on
coral
reef
fish
populations
for
the
first
time.
This
study,
recently
published
in the
journal
Ecology,
demonstrates
consistent
synchronized
changes
in the
size
of
damselfish
populations
on
reefs
separated
by
tens
of
kilometres
and up
to 800
km for
some
species.
| AIMS fish ecologist, Alistair Cheal says these patterns were all strongly associated with a global climatic phenomenon, the El Niño- Southern Oscillation (ENSO), which refers to changes in the ocean and atmosphere that result in a body of unusually warm water building up in the Eastern Pacific Ocean.
Photo: AIMS |
|
The
El
Niño
also
affects
water
temperature,
currents,
wind
and
rainfall
patterns
on the
east
coast
of
Australia.
One
year
after
El
Niño
events,
damselfish
populations
increased
on
many
GBR
reefs.
"El
Niño
events
cause
changes
in
water
temperatures,
wind
speeds
and
patterns
of
water
circulation,
all of
which
can
affect
the
breeding
success
of
reef
fishes
and
survival
of
their
larvae.
"Conditions
during
ENSO
events
in
1995
and
1998
were
good
for
small
reef
fishes…
many
other
reef
organisms
have
similar
life
cycles
and
may
well
have
been
affected
similarly,"
he
adds.
Why
is
this
important
knowledge?
"First
it
shows
that
reef
fish
populations
are
affected
by
climate.
Also
any
changes
in the
nature
of
ENSO
regimes
due to
global
climate
change
will
affect
coral
reef
fishes"
Mr
Cheal
explains
"According
to
some
climate
models,
ENSO
like
conditions
will
become
more
common"
"The
finding
that
distant
populations
change
in
synchrony
means
that
while
conditions
are
favourable,
fish
do
well
across
large
parts
of the
GBR,
but
when
conditions
are
unfavourable
for
recruitment
in one
region,
populations
in
other
areas
will
be
similarly
effected.
"In
such
circumstances,
localized
extinctions
will
be
more
likely,
particularly
for
small
populations
of
short
lived
species,"
Mr
Cheal
explains.
The
synchronizing
effects
of
climate
on
population
dynamics
are
well
documented
for a
range
of
land
animals
but
such
patterns
had
not
previously
been
documented
in
coral
reef
systems
because
of a
lack
of
long
term
and
broad
scale
data.
