How coral reefs can survive climate change

Date:
June 26, 2023
Source:
University of Konstanz
Summary:
Similar to the expeditions of a hundred or two hundred years ago,
the Tara Pacific expedition lasted over two years. The goal: to
research the conditions for life and survival of corals. The ship
crossed the entire Pacific Ocean, assembling the largest genetic
inventory conducted in any marine system to date. The team's 70
scientists from eight countries took around 58,000 samples from
the hundred coral reefs studied.


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FULL STORY ========================================================================== Similar to the expeditions of a hundred or two hundred years ago, the
Tara Pacific expedition lasted over two years. The goal: to research
the conditions for life and survival of corals. The ship crossed
the entire Pacific Ocean, assembling the largest genetic inventory
conducted in any marine system to date. The team's 70 scientists from
eight countries took around 58,000 samples from the hundred coral reefs studied. The first results of the analysis have now been published in
Nature Communications. This largest-ever dataset collection on coral reef ecosystems is freely available and, for years to come, will be the basis
for elucidating the living conditions for corals and finding a way for
them to survive climate change.

Important first results of the expedition: Global microbial biodiversity
is much higher than previously thought. The impacts of the environment
on evolutionary adaptation are species-specific. And, important genes
in corals are duplicated.

Global biodiversity ten times higher than assumed Coral reefs are the
most biologically diverse marine ecosystem on Earth.

Although they cover only 0.16 percent of the world's oceans, they are
home to about 35 percent of known marine species. Using a genetic
marker-based dataset, the researchers found out that all of the
globally estimated bacterial biodiversity is already contained in the microorganisms of coral reefs. "We have been completely underestimating
the global microbial biodiversity," says Christian Voolstra, professor of genetics of adaptation in aquatic systems at the University of Konstanz
and scientific coordinator of the Tara Pacific expedition. He says the
current estimate of biodiversity (approximately five million bacteria)
is underestimated by about a factor of 10.

Impacts of the environment on evolutionary adaptation are species-specific
The 32 archipelagos studied serve as natural laboratories and provide
a wide range of envi-ronmental conditions, allowing to disentangle
the relationships between environmental and genetic parameters across
large spatial scales. This led to another important finding: the effects
the environment has on evolutionary adaptation trajectories of corals
are species-specific. To determine this, the researchers examined the telomeres, the ends of chromosomes that are the carriers of genetic information, for the first time.

In humans, the length of telomeres decreases during life, that is with
an increasing number of cell divisions, suggesting that biological age is closely linked to the length of telomeres. Researchers on the Tara Pacific expedition have now found that the telomeres in very stress-resistant
corals are always the same length. "They apparently have a mechanism to preserve the lengths of their telomeres," Voolstra concludes. In a more stress-sensitive coral species, that also has a shorter lifespan of about
a hundred years, telomere length is aligned to environmental stress,
such as temperature fluctuations. "A direct imprint of environmental
stress levels on organismal resilience may even hold implications for
human health," says Voolstra.

Important genes are duplicated Research data from the Tara Pacific
expedition brought to light that the long life of some coral species
may have yet another reason: the duplication of certain genes. Many
important genes are present multiple times in the genome.

The researchers were able to determine this through sequencing of coral
genomes employing a new high-resolution technique. This technique called long-read sequencing makes it possible to not only determine the set of
genes present, but also to look at their order in the genome. According to Voolstra, the pervasive presence of gene duplication could be a possible explanation for why corals can live for thousands of years despite being exposed, for instance, to extreme UV radiation in shallow waters.

The Tara Pacific expedition, named after the research vessel, will provide material for large-scale analyses of coral reef ecosystem diversity for
years to come. What also makes the programme unique is that samples
were collected from multiple locations and over several years. The
researchers examined the corals at each site in an identical manner,
which makes the results fully comparable.

The entire data collection is freely accessible All datasets are
openly accessible and fully described with accompanying physical and
chemical measurements to provide them as a scientific resource to
all researchers. "This is unique," Voolstra says. "It is the largest
dataset collection on coral reefs ever collected and it is completely
open access." The aspiration is that this data collection will serve as
a foundation and inventory to guide future study of coral reefs worldwide
for many years.

* RELATED_TOPICS
o Plants_&_Animals
# Ecology_Research # Nature # Marine_Biology # Extinction
o Earth_&_Climate
# Ecology # Coral_Reefs # Environmental_Awareness #
Biodiversity
* RELATED_TERMS
o Gray_Whale o List_of_Category_5_Pacific_hurricanes o Ocean
o Giant_clam o Antarctica o Southeast_Asia_coral_reefs o
Greenland_ice_sheet o Artificial_reef

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


========================================================================== Journal Reference:
1. Serge Planes, Denis Allemand. Insights and achievements from
the Tara
Pacific expedition. Nature Communications, 2023; 14 (1) DOI:
10.1038/ s41467-023-38896-6 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2023/06/230626163854.htm

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