Mangroves
are the rainforests by the sea, found at the boundary where land
meets ocean. They serve a wide range of ecological functions,
providing economically valuable products and services. Mangroves,
once estimated to cover an area of over 36 million hectares,
dominated large stretches of tropical coastline. However, due to
ongoing development pressures, mangroves are degraded and their area
substantially diminished relative to their historic range, less than
15 million hectares remain.
Mangrove
forests are vital for healthy coastal ecosystems. The shallow
inter-tidal reaches that characterize mangrove wetlands offer refuge
and nursery grounds for juvenile fish, crabs, shrimps, and molluscs,
and are prime nesting and migratory sites for hundreds of bird
species. Additionally, manatees, crab-eating monkeys, monitor
lizards, Bengal tigers, sea turtles and mudskipper fish utilize the
mangrove wetlands.
Mangroves
play a vital role in protecting sea grasses and coral reefs from
sediments and pollution, filtering out heavy metals and halting
shoreline erosion. Mangroves buffer against hurricane winds, storm
surges and tsunamis, saving thousands of lives, while protecting
infrastructure. Mangroves are also invaluable in combating climate change!
Mangroves,
tidal marshes and seagrass beds remove massive amounts of carbon from the atmosphere and fix it in mangrove soils, where it can remain for
millennia. Unlike terrestrial forests, marine wetlands are constantly
building carbon pools, storing large amounts of so-called "blue
carbon" in highly organic sediments, storing
up to 5-times more carbon per unit area than tropical rainforests.
Their carbon sequestration potential is significant in helping to
reduce atmospheric carbon dioxide. Including
the carbon stored in soils, mangrove forests store the most carbon
per hectare of any other forest type.
Deforestation
and land-use change currently account for 8-20% of global
anthropogenic carbon dioxide (CO2) emissions, second only to fossil
fuel combustion. Destruction of mangroves accounts for around 10% of
emissions from deforestation globally, despite accounting for just
0.7% of tropical forest area. Moreover, if left undisturbed, the
carbon storage by mangroves currently continues to expand through
biological sequestration of CO2 and carbon burial. If current trends
in conversion continue, however, much of the carbon stored in
mangroves along with its future accumulation could be lost.
Mangroves
are among the most threatened and rapidly disappearing natural
environments worldwide, with a much higher rate of loss than other
tropical rainforests. One of the greatest threats to mangroves today
is the rapacious shrimp aquaculture industry, which has caused
massive mangrove losses in Asia and Latin America.
With the current 0.7% rate of loss, most of the world’s mangroves
may disappear by the end of this century.
Conversion
for agriculture or aquaculture, results in massive emissions of
greenhouse gases into the atmosphere, as mangroves change from a sink
for carbon to a massive source. This greatly exacerbates the problems
of global warming.
Restoring
mangrove forests would deliver significant benefits in reducing net
greenhouse gas emissions, improving food security and livelihoods of
coastal communities, increasing resilience in the face of sea level
rise and extreme weather events, and improving habitat for many
vulnerable species along extremely biodiverse tropical coastlines.
Alfredo Quarto is the Executive Director and co-founder of the Mangrove Action Project. You can follow Alfredo on Twitter @mangroveap. For more information visit MAP’s website www.mangroveactionproject.org.
