Barkley, H.C., Cohen, A.L.,
Mollica, N.R., Brainard, R.E.,
Rivera, H.E., DeCarlo, T.M.,
Lohmann, G.P., Drenkard, E.J.,
Alpert, A.E., Young, C.W.,
Vargas-Ángel, B., Lino, K.C.,
Oliver, T.A., Pietro, K.R.
and Luu, V.H.
2018
Repeat bleaching
of a central Pacific
coral reef
over the past
six decades
( 1960-2016 ).
Communications Biology 1:
177, DOI: 10.1038/s42003-018-0183-7.
NOTE:
Climate models
predict that coral
"bleaching" events,
from warm water,
will become
more frequent,
and more severe
in the future,
as a result of
CO2-induced
global warming.
There is concern
about the ability
of corals to survive
even a modest
temperature rise.
SUMMARY:
Many corals
possess
a high degree
of resilience
to temperature
-related stresses,
experiencing
quick recoveries
when the stresses
end.
This coral reef community
had repeatedly experienced
dramatic fluctuations in
ocean temperature.
Rising atmospheric CO2,
and rising ocean temperatures
from El Niño Pacific Ocean
heat releases in the past century,
had no measurable impact
on the coral.
Barkley et al. say their
historical bleaching
reconstruction
"reveals a coral reef community
that has bleached frequently,
and at times catastrophically,
yet appears to have maintained
a healthy state over time."
This fact is
incredibly important
and speaks
to the resilience
of this community
given that
it was ranked
among the healthiest
of all
ocean ecosystems,
notwithstanding
it has experienced
repeated episodes
of moderate to severe
bleaching every
five years."
DETAILS:
The 15 researchers
used skeletal signatures
preserved in long-lived
Porites corals, found on
the reef surrounding
Jarvis Island in the
central Pacific Ocean,
to reconstruct a near
six-decade-long history
of coral bleaching
caused by extreme
El Niño Pacific Ocean
natural heat releasing
events.
Jarvis Island is within the U.S.
Pacific Remote Islands Marine
National Monument
( 0.37°S, 159.99°W )
and represents an uninhabited
coral reef ecosystem that
according to Barkley et al.
"was ranked one of the healthiest
ecosystems in the global ocean
in 2012."
Barkley et al. report that
"two [Porites] cores extend back
to the turn of the 20th century,
and the earliest stress bands
appear in these cores in 1912,
indicating that bleaching occurred
on Jarvis over 100 years ago"
Recurring bleaching events
were also identified prior to
the six decades of their study
( 1960-2016)
-- Jarvis Island has had
a long history of both
moderate
(less than 30%)
and severe
(greater than 30%)
bleaching events,
including the
ten events
in the chart.
CHART BELOW:
Coral reef bleaching
events on Jarvis Island
(mean ± one standard error)
over the period 1960-2016.
