Coral reefs in the Eastern Pacific could survive into the 2060s

Date:
February 13, 2023
Source:
University of Miami Rosenstiel School of Marine, Atmospheric,
and Earth Science
Summary:
Scientists found that some reefs in the tropical Pacific Ocean
could maintain high coral cover into the second half of this
century by shuffling the symbiotic algae they host. The findings
offer a ray of hope in an often-dire picture of the future of
coral reefs worldwide.


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FULL STORY ========================================================================== Scientists at the University of Miami Rosenstiel School of Marine,
Atmospheric, and Earth Science found that some reefs in the tropical
Pacific Ocean could maintain high coral cover into the second half of
this century by shuffling the symbiotic algae they host. The findings
offer a ray of hope in an often-dire picture of the future of coral
reefs worldwide.


========================================================================== While global warming is causing the loss of coral reefs globally,
scientists believe that some corals are increasing their tolerance to
heat by changing the symbiotic algae communities they host, which through photosynthesis provide them with the energy they need to live.

"Our results suggest that some reefs in the eastern tropical Pacific,
which includes the Pacific coasts of Panama, Costa Rica, Mexico, and
Colombia, might be able to maintain high coral cover through the 2060s,"
said coral biologist Ana Palacio-Castro, lead author of the study, alumna
of the Rosenstiel School, and a postdoctoral associate at the school's Cooperative Institute for Marine and Atmospheric Studies. "However,
while this may be seen as good news for these reefs, their survival
may not continue past that date unless we reduce global greenhouse gas emissions and curtail global warming on a larger scale." Shallow coral
reefs in the eastern tropical Pacific Ocean are predominantly built by branching corals in the genus Pocillopora, which are extremely important
for the reefs in the region. The microscopic algae they host in their
tissue harvest light to help the coral produce energy to grow. The loss of these symbiotic algae causes the coral to turn white, or bleach, and the
coral struggles to meet their energy needs, which can often prove fatal.

To better understand how corals improved their tolerance to heat stress,
the researchers examined over 40 years' worth of coral reef-monitoring
data from Panama, one of the longest datasets of its kind in the
world. They analyzed temperature, coral cover, bleaching and mortality
data spanning three ocean heatwaves -- in 1982-1983, 1997-1998, and
2015-2016 -- along with data on algal symbiont community data during
the last two.

The analysis showed that the 1982-83 heatwave significantly reduced
coral cover on the reef, but the effects of the 1997-98 and 2015-16 El
Nin~o were milder, especially for corals in the genus Pocillopora --
sometimes known as cauliflower coral -- the predominant reef-building
coral in the eastern tropical Pacific. They also confirmed that during
strong ocean heatwaves, the heat-tolerant alga Durusdinium glynnii
becomes increasingly common in this particular lineage of corals,
allowing them to better withstand periods of elevated temperatures. When combined with climate projections of future heat stress, the reefs that
were predominantly composed of Pocillopora corals and that hosted this heat-tolerant alga were found to be better equipped to survive and
maintain high levels of coral cover well into the second half of the
current century, indicating that some reef systems may be more resilient
to warming than previously thought.

"This study shows that there are some unusual reefs that may be able
to survive for several decades as a result of their ability to shuffle symbionts," said Andrew Baker, professor of marine biology and ecology
at the Rosenstiel School, and senior author of the study. "While we
don't think that most reefs will be able to survive in this way, it does suggest that vestiges of our current reefs may persist for longer than we previously thought, although potentially with many fewer species. Coral
reefs are incredibly valuable natural assets, providing coastal protection
and fisheries benefits, and supporting many local communities. We can
still make a difference by protecting them." The study was supported by National Science Foundation (NSF) grants (OCE 1447306 and OCE-1358699)
and COLCIENCIAS Scholarship for doctoral studies abroad (#529).

* RELATED_TOPICS
o Plants_&_Animals
# Marine_Biology # Extinction # Sea_Life #
Ecology_Research
o Earth_&_Climate
# Coral_Reefs # Ecology # Global_Warming #
Environmental_Issues
* RELATED_TERMS
o Coral_bleaching o Coral_reef o Coral o Giant_clam o
Dinoflagellate o Artificial_reef o Southeast_Asia_coral_reefs
o Eutrophication

========================================================================== Story Source: Materials provided by University_of_Miami_Rosenstiel_School_of_Marine, Atmospheric,_and_Earth_Science. Original written by Diana Udel. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Ana M. Palacio-Castro, Tyler B. Smith, Viktor Brandtneris, Grace A.

Snyder, Ruben van Hooidonk, Juan L. Mate', Derek Manzello, Peter W.

Glynn, Peggy Fong, Andrew C. Baker. Increased dominance of
heat-tolerant symbionts creates resilient coral reefs in near-term
ocean warming.

Proceedings of the National Academy of Sciences, 2023; 120 (8)
DOI: 10.1073/pnas.2202388120 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2023/02/230213201037.htm

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