Revealing the ramifications of ocean acidification for coralline algae
Researchers find that most coralline algae are negatively affected by
ocean acidification, but some species may be more resilient than others

Date:
November 4, 2021
Source:
University of Tsukuba
Summary:
Researchers have revealed that most coralline algae experience
negative effects from ocean acidification. Analysis of previous
studies showed that changes in ocean chemistry can lead to declines
in calcification rates, abundance, growth, and recruitment of
coralline algae, but some species showed greater resilience than
others. Ocean acidification was revealed as an important driver
of change and the physiology of different species determined their
response to changing conditions.



FULL STORY ========================================================================== Scientists have long suspected that coralline algae are particularly
sensitive to changes in ocean chemistry. Now, researchers have found
that most species of coralline algae studied are negatively affected by
ocean acidification.


==========================================================================
In a new study published in Global Change Biology, an international
team, including researchers from the University of Tsukuba, revealed
that lower seawater pH is associated with decreases in the abundance, calcification rates, and recruitment of coralline algae. As levels of
carbon dioxide increase in the atmosphere, larger amounts are absorbed
by the oceans. The resulting changes in ocean chemistry spell trouble
for calcifying species like corals and coralline algae.

Coralline algae are critical species in shallow marine ecosystems
globally. By creating calcium carbonate skeletons, these algae act as
"cement" for reef systems and provide new substrate for corals and other organisms to settle on.

With ocean acidification, less carbonate is available to build these
skeletons.

The effects of ocean acidification on different species of coralline
algae have been studied for a number of years but the overall outlook
for these species is unclear. The team reviewed all available studies
on coralline algae and ocean acidification and used a variety of methods
to tease out overall patterns.

The clearest trends were the effects of ocean acidification on
calcification; as pH declined, calcification rates decreased. Other
effects included reduced abundance and recruitment. But not all species
respond in the same way.

"Some species seem to be more robust," says Professor Ben P. Harvey,
coauthor of the study. "We found that coralline algae in the family Mesophyllumaceae appear to be more resilient. The physiological responses
of different algae to ocean acidification will affect how resilient,
or susceptible, they are." Key questions remain about those processes
and differences between species.

Ocean acidification is not happening in isolation, and the team also
looked at other drivers of change in these ecosystems, like temperature.

"We know that stressors like temperature and overfishing can have a
strong influence on marine ecosystems," says coauthor Professor Shigeki
Wada. "But it's only fairly recently that ocean acidification has been identified as a large-scale driver of change." When the authors looked
at the relative importance of different influences on calcification rates
and growth, ocean acidification was a dominant factor driving change.

Since the Industrial Revolution, ocean pH has already dropped
by 0.1 units and it seems likely that ocean acidification is
already affecting coralline algae ecology. An important next step is investigating the physiological mechanisms of calcification in different species. Understanding whether some species may acclimatize to changing conditions could provide insights into the future of these shallow
marine ecosystems.

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


========================================================================== Journal Reference:
1. Christopher E. Cornwall, Ben P. Harvey, Steeve Comeau, Daniel L.

Cornwall, Jason M. Hall‐Spencer, Viviana Pen~a, Shigeki Wada,
Lucia Porzio. Understanding coralline algal responses to ocean
acidification: Meta‐analysis and synthesis. Global Change
Biology, 2021; DOI: 10.1111/gcb.15899 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/11/211104115315.htm

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