Ocean acidification puts deep-sea coral reefs at risk of collapse

Date:
September 17, 2020
Source:
University of Edinburgh
Summary:
Deep-sea coral reefs face challenges as changes to ocean chemistry
triggered by climate change may cause their foundations to become
brittle, a study suggests.



FULL STORY ========================================================================== Deep-sea coral reefs face challenges as changes to ocean chemistry
triggered by climate change may cause their foundations to become brittle,
a study suggests.


==========================================================================
The underlying structures of the reefs -- which are home to a multitude
of aquatic life -- could fracture as a result of increasing ocean acidity caused by rising levels of carbon dioxide.

Hundreds of metres below the surface of the ocean in Southern California, researchers measured the lowest -- therefore the most acidic -- pH level
ever recorded on living coral reefs. The corals were then raised in the
lab for one year under the same conditions.

Scientists observed that the skeletons of dead corals, which support and
hold up living corals, had become porous due to ocean acidification and
rapidly become too fragile to bear the weight of the reef above them.

Previous research has shown that ocean acidification can impact coral
growth, but the new study demonstrates that porosity in corals -- known
as coralporosis -- leads to weakening of their structure at critical
locations.

This causes early breakage and crumbling, experts say, that may cause
whole coral ecosystems to shrink dramatically in the future, leaving
them only able to support a small fraction of the marine life they are
home to today.



==========================================================================
The findings complement recent evidence of porosity in tropical corals,
but demonstrate that the threat posed by ocean acidification is far
greater for deep-sea coral reefs.

Research was led by University of Edinburgh scientists, under the
EU-funded ATLAS and iAtlantic projects, with researchers from Heriot-Watt University and the National Oceanic and Atmospheric Administration (NOAA).

The team identified how reefs could become fractured by analysing corals
from the longest-running laboratory studies to date, and by diving with submersibles off US Pacific shores to observe how coral habitat is lost
as the water becomes more acidic.

Dr Sebastian Hennige, of the University of Edinburgh's School of
GeoSciences, said: "This study highlights that a major threat to these wonderful deep-sea ecosystems is structural weakening caused by ocean acidification, driven by the increasing amounts of carbon dioxide we
produce. While deep-sea reefs exist out of sight they are certainly
not out of mind, and our work highlights how scientists from different disciplines and countries can join together to tackle global challenges."
The corals in Southern California -- one the most acidified reefs studied
to date -- are already experiencing the effects of climate change and
exist in conditions that most deep-sea reefs are expected to encounter
by the end of the century, scientists say.



==========================================================================
Dr. Peter Etnoyer, of NOAA's National Centers for Coastal Ocean Science,
said: "Deep-sea corals growing off Southern California are a window
into the future ocean. The region is a natural laboratory to study the
effects of ocean acidification." Submersibles were launched from NOAA
ships off Southern California, and were guided by Dr. Peter Etnoyer and graduate student Leslie Wickes.

The US team sampled live corals and returned them to the laboratory for experiments. The UK team applied engineering principles to demonstrate
the rapid weakening of the skeletons and discovered a striking similarity
to the weakening observed in human bones from osteoporosis.

The team says that the link between osteoporosis and coralporosis opens
up a range of methods and concepts that can be adapted in the challenge
of monitoring and predicting the fate of such fragile deep-sea ecosystems
and the life they support.

Dr. Uwe Wolfram, of Heriot-Watt University, said: "By being able to adapt strategies to coral reefs that are used routinely to monitor osteoporosis
and assess bone fracture risk, we may have powerful non-invasive tools
at our disposal to monitor these fragile ecosystems." Tools developed
as part of the project will aid understanding of when ocean ecosystems
will change and how it will affect marine life.

This will better equip society to deal with how these vulnerable
ecosystems can be protected in the future, and will support the UN Decade
of Ocean Science - - which starts in 2021 -- to deliver the science we
need, for the ocean we want, the team says.

Professor J Murray Roberts, of the University of Edinburgh's School
of GeoSciences, who leads the ATLAS and iAtlantic programmes, said:
"Cold-water corals are truly the cities of the deep-sea providing homes
to countless other animals. If we lose the corals the city crumbles. This project is a great example of how we can work across the Atlantic and
Pacific Oceans to understand the impacts of rapidly changing ocean
conditions." The research is published in the journal Frontiers in
Marine Science. It was supported by the Natural Environment Research
Council, Engineering and Physical Science Research Council, Marine
Alliance of Science and Technology for Scotland, Diamond Light Source,
NOAA, UK Research and Innovation Global Challenges Research Fund and
the European Union's Horizon 2020 Research and Innovation Programme's
ATLAS and iAtlantic projects.


========================================================================== Story Source: Materials provided by University_of_Edinburgh. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Sebastian J. Hennige, Uwe Wolfram, Leslie Wickes, Fiona Murray,
J. Murray
Roberts, Nicholas A. Kamenos, Sebastian Schofield,
Alexander Groetsch, Ewa M. Spiesz, Marie-Eve Aubin-Tam, Peter
J. Etnoyer. Crumbling Reefs and Cold-Water Coral Habitat Loss
in a Future Ocean: Evidence of "Coralporosis" as an Indicator
of Habitat Integrity. Frontiers in Marine Science, 2020; 7 DOI:
10.3389/fmars.2020.00668 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/09/200917105321.htm

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