Geography

Mangroves are coastal ecosystems and represent a type of intertidal forest characterized by salt-tolerant trees, shrubs, and other vegetation that grow in the transition zone between land and sea. Across the world, there are over 50 recognized species of mangroves. Some well-known mangrove species include the red mangrove (Rhizophora), black mangrove (Avicennia), and white mangrove (Laguncularia).

Critical Characteristics of Mangroves

• Salt Tolerance: Mangroves thrive in saline or brackish water environments by filtering salt from seawater, either excreting it through specialized salt glands or retaining it in salt-absorbing cells. For example, red mangroves thrive in areas with soil salinities ranging from 60 to 65 ppt, whereas black and white mangroves are typically located in soils with salinities exceeding 90 ppt.
• Intertidal Habitat: Mangroves grow in the intertidal zone, where they are regularly inundated by tidal waters and exposed during low tide. For instance, the red mangrove (Rhizophora mangle) grows in the intertidal zone along coastlines in the Caribbean.
• Root Systems: Mangrove trees, like Rhizophora mucromataoften have extensive root systems, including stilt roots and prop roots, which help stabilise the trees in soft, muddy soils and allow for oxygen uptake during tidal inundation.
• Biodiversity: These ecosystems support a rich diversity of plant and animal species, serving as important nurseries for marine life. For instance, wild prawns caught off Australia’s Northern Territories and Queensland rely on mangroves for growth and constitute one of the country’s most valuable fisheries, earning almost $72 million a year.
• Coastal Protection: Mangroves act as natural barriers against erosion, storm surges, and tsunamis by dissipating wave energy and thus, stabilize shorelines. For instance, during the 2004 Indian Ocean tsunami, Kapuhenwala, shielded by 200 hectares of healthy mangroves, had only two tsunami-related fatalities. In contrast, Wanduruppa, with degraded mangroves, saw 5,000 to 6,000 deaths in the district.
• Water Quality: Mangroves improve water quality by trapping sediments and filtering pollutants from runoff before they reach the sea. For instance, mangrove forests can enhance water quality by raising dissolved oxygen levels by 32.39% and lowering phosphate, ammonia, and nitrate levels by 88.23%, 73.77%, and 64.28%, respectively.
• Carbon Sequestration: Mangroves sequester carbon from the atmosphere and store it in their biomass and accumulated sediments, thereby contributing to the mitigation of climate change. As an illustration, each mangrove tree planted by Eden Reforestation Projects has the capacity to sequester over 308 kilograms of CO2 from the atmosphere over the course of its lifetime.

Factors Contributing to the Degradation of Mangroves in the Present Times

• Deforestation: The conversion of mangrove areas for agriculture, urban development, and aquaculture has led to widespread deforestation, resulting in the loss of mangrove habitats. To illustrate, about one-fifth of mangroves worldwide have disappeared since 1980, primarily due to clearance for agriculture, often resulting in contamination from waste, antibiotics, and fertilizers.
• Pollution: The discharge of industrial, agricultural, and domestic pollutants, including oil spills, chemicals, and plastic waste, poses a significant threat to mangroves and the dependent wildlife. For instance, India has lost around 40% in its mangrove cover, primarily attributed to urbanization, pollution, and unsustainable activities.
• Climate Change: Mangrove ecosystems are increasingly vulnerable due to rising sea levels, elevated temperatures, and more frequent extreme weather events associated with climate change. For example, climate change-induced sea level rise is projected to result in the total destruction of coastal mangroves in Mexico and an 85 percent loss in the Philippines.
• Tourism: Unregulated tourism and recreational activities in mangrove areas are contributing to habitat destruction, pollution, and disturbances to wildlife. For example, in 1994, tourism-driven development on Union Island in the Caribbean led to the destruction of an ancient mangrove forest. •
• Unsustainable Fishing Practices: Overfishing and the use of destructive fishing methods within mangrove areas deplete fish stocks and harm the overall health of mangrove ecosystems, as observed in the mangroves of Southeast Asia.

Way Forward

• Promote Conservation Initiatives: Implement comprehensive conservation measures, such as designating protected areas and enforcing anti-deforestation regulations. India’s MISHTI scheme serves as a notable example.
• Sustainable Practices: Encourage sustainable practices in agriculture, aquaculture, and fishing to reduce the pressure on mangrove ecosystems. The Sufficiency Economy Philosophy of Thailand serves as a model.
• Climate Resilience: Invest in climate-resilient mangrove restoration and adaptation efforts, including mangrove planting projects in vulnerable areas.
• Tourism Regulations: Establish and enforce regulations for sustainable tourism and recreational activities in mangrove areas to minimize environmental impact, akin to Coastal Regulation Zones (CRZ) in India.
• Pollution Control: Implement stricter pollution control measures and waste management practices to reduce contamination in mangrove environments. Sri Lanka’s successful efforts in this regard serve as a valuable inspiration for preserving its mangroves.
• Community Involvement: Engage local communities in mangrove conservation efforts, fostering awareness and local stewardship of these critical ecosystems. The Community-Based Ecological Mangrove Rehabilitation (CBEMR) project in Indonesia serves as an inspiring example.

Despite being vital components of coastal ecosystems, mangroves are confronted with numerous threats in the present day. Ensuring the preservation of these invaluable coastal environments for future generations necessitates the implementation of unified conservation initiatives, the adoption of sustainable practices, and the elevation of awareness regarding their significance.