The Ecological Engineers: The Lungs of the Sea

by Abdullah S

Seagrass are plants that grow in shallow waters of the ocean. They are similar to the flowering plants on the land. Monocotyledons are a group of plants like grasses, lilies, and palms. Seagrasses belong to Monocotyledons. It is often confused with seaweeds or algae but is different. They have a long oval or strap-like leaves with small flowers and roots. They are evolved from terrestrial plants. They need sunlight to prepare their food through photosynthesis. It is one of the reasons why they can mostly be found in ocean regions lagoons and bays where sunlight can directly pass through. Seagrasses are so-called for their long leaves identical to flowering grasses on land. They are 72 different species of seagrasses in four major classes. They can form dense underwater grasslands that can be seen from space. Seagrass beds provide food and shelter to a diverse range of marine creatures from small organisms to large fishes. Even though it lacks attention from people, it is one of the most effective and productive ecosystems in the world which provides numerous essential services to human beings. Due to the high rate of human interventions, the seagrass beds are tremendously decreasing. All around the globe efforts are going on to restore this highly important and amazing ecosystem.

Source: https://commons.wikimedia.org/wiki/File:Seagrass_Halodule_uninervis_(5777808662).jpg

Seagrass in India
Seagrasses can be found across the coastal regions of India. They are found densely in large areas of Palk Strait and the Gulf of Mannar in Tamil Nadu. Seagrasses can inhabit any type of surface from muddy to rocky. However, the lush green sea grasslands are found covering a dense area mostly in the muddy and sandy surfaces.

Reproduction
Seagrasses reproduce both sexually and asexually. The sexual method is called submarine pollination which is similar to the pollination that happens in terrestrial plants. The sexual method is done by branching off their rhizomes. This character helps them to recover after being eaten by natural grazers like dugongs, manatees, turtles and even destructed by storms.

Source: https://www.bbc.com/news/science-environment-56378397

Benefits of Seagrass
The seagrasses are known for many ecosystem services. Hence they are known as ‘Ecosystem Engineers’.

  • They have a great part in maintaining the water clarity. They trap the dissolved particles in the thick dense grass beds and increase the water clarity. They also filter the nutrients that are released from industries to the ocean.
  • They protect the sea bottom from intense wave actions from ocean currents and stabilize the sea bottom.
  • One square meter of seagrass can produce 10 liters of oxygen every day through photosynthesis. Hence seagrasses are known as ‘The Lungs of the Sea’.
  • Seagrasses act as a nutrient pump in the nutrient-poor region by absorbing nutrients from the soil and releasing it to the water through their leaves.
  • It is the foundation of the coastal food web. The large grazers like dugong, manatees, green turtles feed on the seagrass directly hence maintaining its crop short. Mesograzers like snails and crustaceans feed on the epiphytes and keep the seagrass clean. Dead seagrass feeds as food for decomposers who feed on decaying materials.
  • Air purification: the world seagrass cover absorbs up to 83 million metric tons of carbon every year.

Habitat
A single acre of seagrass cover can support 40,000+ fish and 50 million small invertebrates. The green bed is home to small invertebrates, fishes, mammals, and endless marine animals. The list goes on…

Source: https://www.bbc.com/news/science-environment-56378397

Threats
• Industrial waste
• Propellers of vessels cutting seagrass to small sediments
• Chemical fertilizers and pesticides

Reference
Reynolds reviewed by Emmett Duffy and Nancy Knowlton, P. L. (2018, December 18). Seagrass and Seagrass Beds. Smithsonian Ocean. Retrieved November 16, 2021, from https://ocean.si.edu/ocean-life/plants-algae/seagrass-and-seagrass-beds

Sundararaju , V. (2020, October 19). Why we must conserve the world’s seagrasses. Down To Earth. Retrieved November 16, 2021, from https://www.downtoearth.org.in/blog/wildlife-biodiversity/why-we-must-conserve-the-world-s-seagrasses-73852

Published by LakesOfIndia

Lakes of India is an E.F.I initiative aimed at sensitizing the larger public on freshwater habitats across the country. A blog platform where one can read about lakes across India. You can become a guest blogger to write about a lake in your hometown and initiate an action to protect that lake.

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