Mangroves: The first line of defence against cyclones, tidal ingress

Mangroves are salt tolerant plant communities found in tropical and sub-tropical intertidal regions of the world.

They are a group of vascular plants having special morphological, physiological and other non-visible adaptations to live in a saline intertidal environment dominated by low dissolved oxygen and sometimes anoxic fine sediments.

With one foot on land and another in the water, these botanically amphibians occupy a zone of desiccating heat, choking mud and salt levels that would kill an ordinary plant within hours.

Mangrove cover in world

As per Global Forest Resources Assessment-2020, at least 113 countries across the globe have mangrove forests, covering an estimated 14.79 million hectares.

The largest mangrove area is found in Asia (5.55 million hectares), followed by Africa (3.24 million hectares).

More than 40 per cent of the total area of mangroves was reported to be in just four countries: Indonesia (19 per cent), Brazil (9 pc), Nigeria (7 per cent) and Mexico (6 pc).

Mangrove cover in India

As per the India State of Forest Report (ISFR)-2021, India has 4,992 square kms of mangrove cover, which is 0.15 per cent of the country’s total geographical area.

India has 1,475 sq kms of very dense mangrove, 1.481 sq kms of moderately dense mangrove and 2,036 sq kms of open mangroves.

Mangroves are mainly found in West Bengal, Tamil Nadu, Odisha, Andhra Pradesh, Gujarat and Andaman & Nicobar Islands.

Nearly 57 per cent of the mangroves are found along the east coast of India.

Mangroves in Odisha

The mangroves of Odisha are distributed in three major zones: mangroves of Mahanadi delta, mangroves of Brahmani and Baitarani delta (Bhitarkanika), and mangroves of Balasore-Bhadrak coast.

Bhitarkanika mangroves are most important due to its largest stretch and unique biodiversity. It is also considered as the third largest mangrove zone in the country after Sundarbans and Andaman & Nicobar island.

This belt located in Kendrapara district comprises of coastal areas between Dhamra mouth and Barunei and has been notified as Bhitarkanika Sanctuary, spread over 672 sq kms area. Part of this area (145 sq kms) has also been notified as National Park. This stretch of mangrove is relatively well preserved.

Mangrove vegetation in Mahanadi delta region between Barunei mouth to Mahanadi mouth is fragmented and degraded due to large scale encroachment.

Sparse mangrove vegetation is also found in Jagatsinghpur, Puri and Ganjam districts. The outer channel of Chilika lagoon has also small patches of mangroves.

The major mangrove species in Odisha are: Avicennia alba, Avicennia officinalis, Rhizophora mucronata, Excoecaria agallocha, Acanthus ilicifolius, Sonneratia apetala and Heritiera fomes.

Significance of Mangrove Ecosystem  

Mangroves play a very significant role in protecting the hinterlands against cyclones and ingress of sea water during tidal surge. Mangroves stabilize coastal land mass against sea erosion. They are the first line of defence for coastal communities.

Mangroves are repositories of immense biological diversity and are also the nursery and breeding ground of several marine life forms including species of prawns, crabs and fishes. Mangroves sustain the ecological security of the coastal areas as well as livelihood security of the thousands of fisherman and other who leave in these areas.

[This story is a part of ‘Punascha Pruthibi – One Earth. Unite for It’, an awareness campaign by Sambad Digital.]