Scientists take samples of seagrass beds at NSF’s Florida Coastal Everglades LTER site. Credit: NSF Florida Coastal Everglades LTER Site |
Seagrasses
are a vital part of the solution to climate change and, per unit area,
seagrass meadows can store up to twice as much carbon as the world’s
temperate and tropical forests.
So report researchers publishing a paper this week in the journal Nature Geoscience.
The
paper, “Seagrass Ecosystems as a Globally Significant Carbon Stock,” is
the first global analysis of carbon stored in seagrasses.
The
results demonstrate that coastal seagrass beds store up to 83,000
metric tons of carbon per square kilometer, mostly in the soils beneath
them.
As
a comparison, a typical terrestrial forest stores about 30,000 metric
tons per square kilometer, most of which is in the form of wood.
The
research also estimates that, although seagrass meadows occupy less
than 0.2% of the world’s oceans, they are responsible for more than 10%
of all carbon buried annually in the sea.
“Seagrasses
only take up a small percentage of global coastal area, but this
assessment shows that they’re a dynamic ecosystem for carbon
transformation,” said James Fourqurean, the lead author of the paper and
a scientist at Florida International University and the National
Science Foundation’s (NSF) Florida Coastal Everglades Long-Term
Ecological Research (LTER) site.
The
Florida Coastal Everglades LTER site is one of 26 such NSF LTER sites
around the world in ecosystems from forests to tundra, coral reefs to
barrier islands.
“Seagrasses
have the unique ability to continue to store carbon in their roots and
soil in coastal seas,” said Fourqurean. “We found places where seagrass
beds have been storing carbon for thousands of years.”
The
research was led by Fourqurean in partnership with scientists at the
Spanish High Council for Scientific Investigation, the Oceans Institute
at the University of Western Australia, Bangor University in the United
Kingdom, the University of Southern Denmark, the Hellenic Center for
Marine Research in Greece, Aarhus University in Denmark and the
University of Virginia.
Seagrass meadows, the researchers found, store 90% of their carbon in the soil—and continue to build on it for centuries.
In
the Mediterranean, the geographic region with the greatest
concentration of carbon found in the study, seagrass meadows store
carbon in deposits many meters deep.
Seagrasses
are among the world’s most threatened ecosystems. Some 29% of all
historic seagrass meadows have been destroyed, mainly due to dredging
and degradation of water quality. At least 1.5% of Earth’s seagrass
meadows are lost every year.
The
study estimates that emissions from destruction of seagrass meadows can
potentially emit up to 25% as much carbon as those from terrestrial
deforestation.
“One
remarkable thing about seagrass meadows is that, if restored, they can
effectively and rapidly sequester carbon and reestablish lost carbon
sinks,” said paper co-author Karen McGlathery, a scientist at the
University of Virginia and NSF’s Virginia Coast Reserve LTER site.
The Virginia Coast Reserve and Florida Coastal Everglades LTER sites are known for their extensive seagrass beds.
Seagrasses
have long been recognized for their many ecosystem benefits: they
filter sediment from the oceans; protect coastlines against floods and
storms; and serve as habitats for fish and other marine life.
The
new results, say the scientists, emphasize that conserving and
restoring seagrass meadows may reduce greenhouse gas emissions and
increase carbon stores–while delivering important “ecosystem services”
to coastal communities.
The
research is part of the Blue Carbon Initiative, a collaborative effort
of Conservation International, the International Union for Conservation
of Nature, and the Intergovernmental Oceanographic Commission of UNESCO.
Source: National Science Foundation
