Mangroves - Thought Chakra

Mangroves – UPSC Environment Notes

A Mangrove is a small tree or shrub that thrives along coastlines, establishing roots in saline soil, usually submerged. The term “mangrove” encompasses both the overall environment and the trees and shrubs within the mangrove forest. Mangrove forests serve as a natural barrier against storm surges, currents, waves, and tides. This article aims to provide insights into mangroves, offering valuable information for Environment preparation in the UPSC Civil Service Exam.

Mangroves

Mangroves

  • Mangroves: Littoral plant formation along tropical and subtropical coastlines
  • Characteristics:
    • Trees and bushes thriving beneath high spring tide water levels
    • Remarkable salt water tolerance
    • Salt-resistant and heat-resistant in tropical and subtropical intertidal zones worldwide
    • High rainfall (1,000 to 3,000 mm) and temperatures (26°C to 35°C)
  • Adaptations:
    • Morphological, anatomical, and physiological adaptations for wet soils, high salinity, storms, and tide surges
  • Geographic Distribution:
    • Found only around the equator in tropical and subtropical latitudes
  • Roots:
    • Prop roots into the water
    • Air roots vertically structured from the mud
    • Stilt roots (adventitious roots) from the main trunk
  • Classification:
    • Red mangroves on coastlines
    • Black mangroves with dark bark and more oxygen
    • White mangroves at the highest elevation
  • Ecological Importance:
    • Key habitats for coastal biodiversity
    • Nursery habitat for marine species (shrimp, crabs, fish)
    • Coastal erosion mitigation and storm damage reduction
    • Bio-shields protecting against floods
  • Human Dependence:
    • Biomass-based occupations for many, especially in rural areas
Prop Roots - Thought Chakra
Pneumatophores - Thought Chakra

Characteristics of Mangroves

  • Mangroves are integral to the Littoral Forest ecosystem.
  • Found primarily between latitudes 25° N and 25° S in tropics and subtropics globally.
  • Feature a complicated salt filtering system and a complex root system.
  • Mangrove forest trees typically reach heights of 8-20 meters.
  • Possess special roots known as breathing roots or pneumatophores for oxygen collection from the atmosphere.
  • Survive in hostile conditions: excessive salt, muddy water, low oxygen levels, high temperature, and high water tides.
  • Viviparity mode of reproduction: Tree seeds germinate within the tree before falling.
  • Highly productive ecosystems, usually evergreen woods thriving in tropical and subtropical climates.
  • Flourish in areas like sheltered low-lying beaches, estuaries, mudflats, tidal creeks, backwaters, marshes, and lagoons.
  • Important species in Indian mangrove forests include:
    • Avicennia officinalis
    • Rhizophora mucronata
    • Sonneratia alba
    • Avicennia alba
    • Bruguiera cylindrica
    • Heritiera littoralis
    • Phoenix paludosa
    • Morinda citrifolia

Mangroves in India

  • Country’s total geographical area encompasses diverse landscapes.
  • Odisha and Maharashtra have experienced significant increases in mangrove cover.
  • Deltas of the Ganges, Mahanadi, Krishna, Godavari, and Kaveri rivers host mangrove forests.
  • Top 5 states in India with the most mangrove forest cover:
    • West Bengal: 2,114 sq km
    • Gujarat: 1,175 sq km
    • Andaman and Nicobar Islands: 616 sq km
    • Andhra Pradesh: 405 sq km
    • Maharashtra: 324 sq km
    • Odisha: 259 sq km
  • Indian mangroves comprise 46 species in 22 genres.
Mangrove Cover Assessment - Thought Chakra
  • The Sundarbans mangroves represent the world’s largest single block of tidal holophytic mangroves.
  • Major species in this dense mangrove forest include Heritiera fames, Rhizophora spp., Bruguiera spp., Ceriops decandra, Sonneratia spp., and Avicennia spp. with Nypa fruticans along the creeks.
  • Home to the Royal Bengal Tiger and crocodiles, this mangrove forest faces threats from agricultural land conversion.
  • The Bhitarkanika mangroves in Orissa, the second largest in the Indian subcontinent, boast a high concentration of typical mangrove species and high genetic diversity.
  • In Andhra Pradesh’s Godavari-Krishna deltaic regions, mangrove swamps flourish in the intertidal mudflats on both sides of the creeks.
  • Pichavaram and Vedaranyam mangroves suffer from degradation due to aquaculture ponds and salt pans construction.
  • In Maharashtra, Goa, and Karnataka on India’s west coast, mostly scrubby and degraded mangroves occur along the intertidal region of estuaries and creeks.
  • The mangrove vegetation in Kerala’s coastal zone is sparse and thin.
  • In Gujarat’s northwest coast, Mangroves Avicennia marine, Avicennia officinalis, and Rhizophora mucronata are primarily found in the Gulf of Kachchh and the Kori creek.
  • Scrubby mangroves with stunted growth form narrow, discontinuous patches on soft clayey mud.
  • The condition of the mangroves, especially in the Kori creek region (Indus river paleodelta), is improving.
  • Mangroves vary in size from bushy stands of dwarf mangroves in the Gulf of Kuchchh to taller stands in the Sundarbans.
  • The Andaman and Nicobar Islands’ small tidal estuaries, neritic inlets, and lagoons support a dense and diverse undisturbed mangrove flora.
MangrovesFeatures
Sundarbans (West Bengal)– Largest mangrove forest region globally. <br> – Listed as a UNESCO World Heritage Site. <br> – Spans approximately 10,000 sq km across Bangladesh and India. <br> – Key Species: Royal Bengal tiger, Gangetic dolphins, and Estuarine crocodiles.
Bhitarkanika Mangroves (Odisha)– Second largest mangrove forest in India. <br> – Formed by the river deltas of River Brahmani and Baitarani. <br> – Recognized as Ramsar wetlands in India. <br> – Key Species: Saltwater crocodiles, Largest known nesting site for Olive Ridley sea turtles.
Godavari – Krishna Mangroves (Andhra Pradesh)– Extends from Odisha to Tamil Nadu. <br> – Located in the delta of Godavari and Krishna rivers. <br> – Ecoregion under protection for Calimere wildlife and Pulicat Lake Bird Sanctuary.
Pichavaram Mangroves (Tamil Nadu)– One of the largest mangrove forests globally. <br> – Habitat for many aquatic bird species.
Mangrove Profile in India - Thought Chakra

Mangroves in World

  • According to the Global Forest Resource Assessment 2020 (FRA 2020), 113 countries worldwide feature Mangrove forests, covering an estimated 14.79 million hectares.
  • Asia boasts the largest mangrove areas, followed by Africa, North and Central America, and South America.
  • Oceania has the smallest amount of mangroves.
  • Over 40% of the total mangrove area is concentrated in just four countries: Indonesia (19%), Brazil (9%), Nigeria (7%), and Mexico (6%).
  • Role of Mangroves

Role of Mangroves

  • Mangrove plants feature unique roots like prop roots and pneumatophores, contributing to water flow obstruction, enhancing sediment deposition, stabilizing coastal shores, and creating breeding grounds for fishes.
  • They play a crucial role in preventing coastal soil erosion.
  • Mangroves house a diverse range of vegetation, avifauna, and wildlife.
  • Environmentally essential, mangroves act as a reservoir in the tertiary waste assimilation process.
  • They are vital in supporting land accretion, mud bank stabilization, and energy dissipation from wind, tidal, and wave forces.
  • Mangroves enhance water quality by absorbing nutrients, preventing toxic algal blooms offshore.
  • Stabilizing coastlines, mangrove trees reduce erosion caused by storm surges, currents, waves, and tides, defending coastal areas from tsunamis, hurricanes, and flooding.
  • Serving as breeding habitats, mangroves protect a variety of fish and provide shelter for a diverse range of animals, including birds, invertebrates, mammals, and plants.
  • They promote natural nutrient recycling.
  • Mangroves offer locals resources like wood, firewood, medicinal plants, and edible plants.
  • Providing a vital source of income for coastal populations, mangroves are relied upon for honey, tannins, wax, and fishing.
  • Mangroves contribute to decreasing the inundation of coastal lowlands by reducing monsoonal tidal floods and act as significant carbon sinks.

Threat to Mangroves

  • Biotic pressure and natural disasters significantly impact Mangrove ecosystems.
  • The growing land acquisition for agriculture and industry along coasts, along with the discharge of untreated domestic sewage and industrial effluents, and pesticide residues from agricultural lands, pose threats to these forests.
  • Upstream operations such as river training and natural erosion and accretion affect mangrove health, as the adequate ecological flow in rivers is necessary to flush silt and pollutants from the mangroves.
  • Climate change, including rising sea levels, contributes to the diverse extinction of mangrove ecosystems.
  • Aquaculture, particularly the conversion of mangrove cultivation into shrimp farming, poses serious threats to the mangrove ecosystem.

Measures Taken to Protect Mangroves

  • 1892: The Sundarbans becomes the world’s first scientifically managed mangrove forest.
  • 1976: The Environment Ministry establishes The National Mangrove Committee.
  • 1979: Recommendations include mangrove mapping using remote sensing, land surveys, and other methods to identify degradation rates, analyze sites for reserve forests, and implement conservation programs and afforestation.
  • 2005: The Mumbai High Court classifies mangroves as forests.
  • 2013: In the Sundarbans, the Biotechnology Department initiates an experimental bio-restoration project, using native grasses to stabilize degraded mangrove stretches (salt-tolerant varieties).
  • 2016: The Maharashtra government designates over 15,000 hectares of mangroves as reserve forest, prohibiting construction within 50 meters of these areas.
  • 2018: The High Court rules that mangrove destruction violates citizens’ fundamental rights under Article 21 of the Constitution.
  • 2018: The BOBLME (Bay of Bengal Large Marine Ecosystem) project, led by the United Nations Food and Agriculture Organization and funded by GEF (Global Environment Facility), brings together India and seven other Bay of Bengal region countries to safeguard mangroves.

Conclusion

  • Mangrove systems are abundant in biodiversity and offer various ecological services. They play a major role in protecting coastal areas from natural disasters, thereby conserving the environment.
  • Highly productive ecosystems, mangroves can export energy and materials to neighboring communities. They support a diverse heterotrophic food chain, act as nurseries in some organisms’ life cycles, and provide protection against coastal erosion and storm surge attacks.
  • However, they are currently under severe anthropogenic pressures, similar to many other types of wetlands.

FAQs on Mangrove

Question: What is the definition of a “mangrove” forest?

Answer: A mangrove forest is a unique coastal ecosystem characterized by salt-tolerant trees and shrubs. These plants grow in saline or brackish water and have special adaptations to thrive in the intertidal zones of tropical and subtropical coastlines.

Question: Which country is home to the world’s largest mangrove forest?

Answer: The world’s largest mangrove forest is located in Bangladesh and India, known as the Sundarbans. This vast and biodiverse mangrove ecosystem spans across approximately 10,000 square kilometers and is recognized as a UNESCO World Heritage Site.

Question: Where can you find a mangrove forest in India?

Answer: Mangrove forests are prevalent along the coastal regions of India. Some notable locations include the Sundarbans in West Bengal, Bhitarkanika in Odisha, Godavari-Krishna mangroves in Andhra Pradesh, and Pichavaram in Tamil Nadu. Additionally, Maharashtra, Goa, and Kerala also have mangrove ecosystems along their coastal areas.

UPSC PYQ Prelims

Question: Which one of the following is the correct sequence of ecosystems in the order of decreasing productivity? [UPSC 2013]

  • (a) Oceans, lakes, grasslands, mangroves
  • (b) Mangroves, oceans, grasslands, lakes
  • (c) Mangroves, grasslands, lakes, oceans
  • (d) Oceans, mangroves, lakes, grasslands

Answer: (c)

Question: What is/are unique about ‘Kharai Camel’, a breed found in India? (UPSC 2016)

  1. It is capable of swimming up to three kilometers in seawater.
  2. It survives by grazing on mangroves.
  3. It lives in the wild and cannot be domesticated.

Select the correct answer using the code given below.

  • (a) 1 and 2 only
  • (b) 3 only
  • (c) 1 and 3 only
  • (d) 1, 2 and 3

Answer: (a)

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