Mangroves, Carbon Sequestration, Harbor Infrastructure and Coastal Degradation

Urbanization and Invasion of Mangroves Swamps

The rapid increase in population and corresponding urbanization in coastal megacities has been accompanied by frenzied land reclamation driven mostly by anthropogenic factors . Mangroves are prevalent all over except Antarctica. Seaward  land reclamation  entails the
formation of artificial land facade structures extending over the sea employing innovative engineering designing. Coastal megacities have flourished rapidly over the last four decades leading to massive and uneducated land reclamation. To placate conservations the trend is
planting of fresh mangroves instead of incentivizing conservation of existing mangrove forests. National economic priorities spur infrastructure development, coastal economic development zones and enlargement of port facilities.

Mangroves Global Spread

Asia has the biggest tract area of mangrove coverage comprising almost 42% of the world’s
mangroves and predominantly swamps are found in Indonesia and Malaysia . The State of
Florida in the US encompasses almost 190,000 ha and its prominent species include wading
birds, pelicans as well as the endangered crocodile.

Mangroves Benefits

For those not exposed to marine conservation suffice to say that mangrove swamps are
coastal wetlands typically prominent in tropical and subtropical regions exemplified by
halophytic trees and shrubs having the unique ability to thrive in brackish to saline tidal
waters. Mangrove swamps flourish as estuaries at the juncture of fresh and salt water
resplendent with an amazing and impenetrable maze of woody habitat. From a marine
conservationist perspective mangrove forests enable ecosystems to sustain endangered
species as nurseries for fish and marine species including shellfish, worms, protozoa,
barnacles ,oysters , juvenile fish , shrimps and other invertebrates. From mangrove refuges
marine species enter reefs critically replenishing the ocean’s fish stock a vital source of
livelihood for many developing maritime countries. Some megacities have untreated sewage
and effluence entering rivers from industrial complexes and emptying into the sea.
Diverse geospatial consequences of complex coastal geomorphology combined with natural
and anthropogenic elements emphasize the susceptibility of coastlines to external sea surges
.Swamps shelter harbors and coastlines from siltation , erosion ,sea swells and damages of
storm surges .The UN Environment Programme is about mangrove forests sequestering
carbon within their roots, trunks and in the soil estimated at 22 million tons of carbon
annually. Salt marshes or coastal vegetated ecosystems enable marine species survival , stabilize
shorelines and prevents erosion which naturally protects critical port infrastructure and
manages carbon sequestration. There is no cavil to the proposition that mangrove ecosystems offer significant benefits to coastal regions, including serving as nurseries for local fish, acting as natural water filtration systems and acting as a buffer against coastal storm surges damage. Despite massive investments many post tsunami mangrove restoration projects in countries like Sri Lanka depict success rates of 20 % only.

Coastal Reclamation Megaprojects

The glittering spectacle of the Palm Resorts of Dubai , construction of the new Hong Kong
airport, artificial islands in the South China Sea , development of “Baia de Luanda” in
Angola and the construction of a contiguous Mumbai from islands are manifestations of
marine reclamation. In contrast to the edifice of the Palm Resorts of Dubai the Flevoland
province in Netherlands was artificially made through draining lakes making it the youngest
province as it came into being in the year 1986 . The uniqueness of its design is that it is the
largest man made island in Netherlands and is protected by embankments or dykes . Despite
being below sea level the Flevoland province is reflective of flood risk management
engineering designing against storm surges from the North Sea which had wrecked havoc in
the past. Flevoland also serves as a fresh water logistic and touristic hub replete with the
world famed tulips . Megacities are conspicuously coastal and the extent of coastal land
expansion and potential environmental impact can be deduced from coastal megacities
developed from the years 1985 to 2019 . The Global Diversity report 5 has identified coastal
degradation , untreated sewage and pollution from plastic waste as severely impacting marine
ecosystems such as coral reefs .

International Rationale for Mangroves Conservation

The South Carolina (S.C.) State Ports Authority created 22 ares of salt marshlands on Dawn
Islands as a precursor to making it the greenest port in the Southeast. The S.C State Ports
Authority abandoned plans for a new cruise ship terminal the permitting of which had
attracted the ire and legal challenge from environmental and historic preservation groups. The
marshy swamps creation was required by federal permit for the Leatherman terminal the
construction of which had caused the destruction of wetlands . The project cost around $4
million involving the conversion of a dormant dredge disposal site , an aquatic habitat to
invasive species , into a wetland with more than 100,000 native marsh plants. The project is
hailed as a contemporary green flagship success story .The restored salt marsh in Charleston
Harbor is said to have improved water quality establishing an aquatic habitat for juvenile
shrimp , fish and invertebrates of the creek and un interrupted tidal flow from the harbor
.Sporadic marine conservation efforts are underway in Kenya’s Gasi Bay through planting of
seedlings . Nigeria has the largest reserve of water friendly trees in Africa but the country’s
mangroves are ranked amongst the worst degraded compelling the country to launch a
mangrove sustainability initiative to increase mangrove cover.

Carbon Sequestration Potential of Mangroves

Maximum canopy height is an indicator of light interception that reflects the carbon storage
potential or carbon sequestration naturally capable of reducing atmospheric concentration of
carbon dioxide. Additionally if marine species diversity influences carbon storage the
complementarity hypothesis is substantiated as being a mechanism for the storage of blue
carbon. Mangroves contribution towards protecting juvenile marine species, its role in tidal
flow and preventing siltation in harbors, protecting port infrastructure against ocean swells ,
carbon sequestration and preserving estuaries is in contemporary times being gradually
recognized as invaluable.

Mangroves Mitigate Coastal Climate Change

Mangroves play a crucial role in mitigating coastal climate change disasters being natural barriers absorbing the impact of storm surges, reducing coastal erosion and protecting inland areas from flooding. The complex root systems of mangroves stabilize shorelines, trap sediments, and prevent land loss. Mangroves also act as carbon sinks, sequestering significant amounts of carbon dioxide from the atmosphere, thus contributing to the reduction of global greenhouse gas levels. Mangroves support biodiversity through providing habitat for numerous marine and terrestrial species which enhances the resilience of coastal ecosystems to climate change impacts.

 

By Nadir Mumtaz 

Credit/ References  :

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