Mangroves’ most important ecosystem
service, scientists say, may be mitigating
climate change by removing greenhouse
gases from the atmosphere. Like other
plants, mangroves capture carbon diox-
ide and store it in their leaves, roots, and
trunks (biomass) and in the soil. But unlike
most other forests, mangroves do not
have a maximum storage capacity. They
continuously amass carbon in soil, where
it can remain for millennia.
Mangroves are extremely productive
ecosystems that can increase their bio-
mass relatively quickly, trapping more car-
bon than other forest types. The upper
meters of mangrove soils are primarily
anaerobic—missing the organisms that
decompose organic material and release
carbon into the environment.
How much “blue carbon”—carbon cap-
tured by the world’s coastal and ocean eco-
systems—is stored in mangrove forests?
Researchers mapped mangroves and
identified which ones contain the most
blue carbon: mangals in Sumatra, Borneo,
and New Guinea, and along the coasts of
Colombia and northern Ecuador.
The findings were published in 2013
in the journal Conservation Letters. The
results can help guide decisions about pri-
ority areas for mangrove conservation and
rehabilitation, scientists say.
When mangrove forests are converted
to agriculture or to aquaculture ponds,
the majority of the carbon in their bio-
mass and underlying soils is released into
the atmosphere, joining other sources of
greenhouse gases. Clearing even small
tracts of mangroves generates high vol-
umes of carbon dioxide.
“These forests have been absorbing
carbon for the last 4,000 or 5,000 years,
but now through deforestation they have
become significant sources of green-
house gas emissions,” Kauffman says.
“Because they store so much carbon,
they’re important sites for mitigating or
slowing climate change.”
HOW MUCH IS A MANGROVE
FOREST WORTH?
An important question, say Kauffman and
coauthors, is whether the value of the
shrimp or beef produced from a former
mangrove forest exceeds the value of the
ecosystem services lost as a result of man-
grove conversion. Those ecosystem ser-
vices include maintaining high biodiversity,
fisheries production, protection against
storms and erosion, and carbon storage.
“Addressing this trade-off is the respon-
sibility of governments and is the personal
choice of the consumer, who should have
access to information on the true costs
and impacts of food production,” the
researchers write.
“A better understanding of land-use
carbon footprints would provide context
to make informed decisions about how
our everyday lives affect land use and
climate change.”
And whether that surf-and-turf dinner is
worth the price—in mangrove currency.
Cheryl Lyn Dybas (cheryl.lyn.dybas@gmail.com), a Fellow of the International League of
Conservation Writers, is a contributing writer for Oceanography and a marine ecologist by training.
She also writes about science and the environment for National Geographic, BioScience, Ocean
Geographic, Canadian Geographic, National Wildlife, Yankee, and many other publications.
Background photo: Women in the Sundarbans
mangrove forest, Bangladesh. From top to
bottom on left: (1) Brazilian fisher with a man-
grove forest in the background. (2) Abandoned
fish pond showing mangrove devastation.
(3) Dried-up shrimp pond in Brazil. Courtesy of
J. Boone Kauffman, Oregon State University
Oceanography | Vol.30, No.3
Oceanography | Vol.30, No.3