Mangroves and their role as agents against coastal erosion

Francois Doumenge, in his article ‘Mankind belongs to the sea’, mentions that about 65% of cities with an average 2.5 million population each are located on the seashores. He suggests that the world’s coastal areas will be home to about 70% of the total human population in near future. 

This means that seas are central to human existence, but at the same time they could pose dangers to that massive population that lives on shores if some safeguards are not taken to protect the land that the seas might consume. It is estimated that if sea ingress is not checked then Karachi, Badin and Thatta face a grave threat of sinking by 2060. One of the elements that help keep the coasts safe from sea water inflow is the mangroves. Covering an area nearly 50,000 square kilometres and spanning nearly 120 countries, the mangroves are essentially plants on the coast like a ‘soldier on the wall’ guarding the land against salt water influx from sea. With their unique ability to stand strong against the wave energy and exceptionally high salt contents, they are also called halophytes – i.e., plants that grow and remain alive in a high salt region. Mangroves’ roots system slows down the incoming water at the time of high tides. Sediments of the sea water are deposited at the mangroves’ roots and are washed away once the tides ebb. Due to their role in marine ecosystem and the natural protection they provide against erosion, mangroves must be made a part of biodiversity and conservation programmes that are taking place in Pakistan.

Spread over a length roughly 150 km, Indus Delta mangroves form an important part of marine ecosystem that concerns Pakistan. Mangroves in Indus Delta are said to be ‘saltier’ than any other form of the same plant found elsewhere in the world. These Deltaic mangroves receive salt from both directions: salt brought with it from the Thar Desert by Indus River and the other salt given by the waves of Arabian Sea. The Deltaic mangroves are diminishing at a higher rate – especially in the last 3 decades. The reason is simple: lower outflow of Indus River because of its excessive use for irrigation and the increasing level of marine pollution. A study suggests that Indus River’s freshwater flow is down by 90% compared to its usual levels couple of decades ago. With slow freshwater flows, the sea water intrudes upstream by about 80 km; formidably affecting both mangroves and cultivable land. Overall, the impact is higher sea levels and coastal erosion. This is practically visible in areas of Keti Bandar, where nearly 20 km landward area appears to have been affected by coastal erosion.

Mangroves found in Indus Delta are mainly ‘grey mangroves’, known in Taxonomy as avicennia marina and cover an area of about 820 square kilometres. These plants are home to large quantities of shrimps, mud lobsters and crabs. Among the land animals, a unique type of cat called prionailurus viverrinus is found in the mangroves, which has already been declared as an ‘endangered species’. Flamingos and pelicans are the type of birds that are usually found in the Indus Delta region, whereas, according to Mark Spalding’s book ‘World Atlas of Mangroves’, nearly 60,000 birds from the temperate regions of the Northern hemisphere spend winters in the Indus Delta.

Sensing the dangers of depletion of mangroves and its consequential impact on coastal erosion, Pakistan started a campaign in 1985 in cooperation with International Union of Conservation of Nature (IUCN) to plant mangroves saplings. The effort, however, was not truly result-oriented and only an area of 50 square kilometres was planted. Nonetheless, in a similar campaign on 22 June 2013, nearly 750,000 mangrove saplings were planted making it a world record. The need is now felt to increase the momentum of this effort. Following suit the Prime Minister’s initiative of ‘Green Pakistan’, Chief of the Naval Staff has launched a ‘Pakistan Navy - Mangroves Plantation Campaign (PN-MPC)’. In this campaign, which was launched on 21 March 2016, Pakistan Navy plans to plant 1 million mangrove saplings before the end of monsoon season all along Pakistan’s coast. MPC is a comprehensive campaign and will be orchestrated jointly by Sindh & Balochistan Forest Departments and IUCN.

Pakistan Navy has always played its part in protection of marine ecosystem and conservation of the environment. It is alive to the dynamicity of global climate change and its impact on our lives. MPC is one of those initiatives that the Navy has self-imposed upon itself and is all prepared to participate in the national cause very meaningfully.