Shankar IAS Summary: Marine Organisms- 2 | Famous Books for UPSC Exam (Summary & Tests) PDF Download

Introduction

Marine organisms encompass a diverse array of life forms adapted to the unique challenges of life in the world's oceans and seas. From microscopic plankton drifting near the ocean's surface to majestic whales traversing its depths, marine life spans a vast spectrum of sizes, shapes, and ecological roles. These organisms play crucial roles in maintaining the health of marine ecosystems, contributing to processes like nutrient cycling, oxygen production, and the regulation of global climate.

Sea Grass

Sea grasses are marine flowering plants (angiosperms) with a grass-like appearance, producing flowers, strap-like or oval leaves, and a root system.

• They thrive in shallow coastal waters with sandy or muddy bottoms, requiring relatively calm areas.
• Unique as the only group of higher plants adapted to life in saltwater. 
• Major sea grass meadows in India are found along the south-east coast of Tamil Nadu and in the lagoons of a few Lakshadweep Islands, with some grass beds around Andaman and Nicobar islands.
• The abundant growth of seagrasses in Tamil Nadu and Lakshadweep is attributed to high salinity, water clarity, and sandy substrate.

Functions of Sea Grass

1. Sea grass beds physically help:
   • Reduce wave and current energy.
   • Filter suspended sediments from the water.
   • Stabilize bottom sediments to control erosion.
2. Provide habitat for marine invertebrates and fishes.
3. Enhance fish and migratory bird populations in lagoon areas by offering food and shelter.
4. Act as nutrient sinks on reef flats and near estuaries, buffering or filtering nutrient and chemical inputs to the marine environment.

Do you know?

The five species of turtles nesting on the Indian coast are Leatherback sea turtle, Green turtle, Olive Ridley, Hawksbill, and Loggerhead turtle.

• IUCN prioritizes the conservation of sea grass.
• Out of 58 world species, fourteen seagrass species are recorded from the Indian coast.
• Commonly distributed from inter-tidal to sub-tidal regions down to 8m depth.
• Dugong, a mammal dependent on sea grass for food, is on the verge of extinction.

Threats to Sea Grass Beds

• Environmental Threats

   Eutrophication, siltation, and coastal engineering harm seagrass beds. Eutrophication leads to algal blooms, siltation reduces sunlight penetration, and coastal constructions disrupt natural habitats.

• Human-Induced Pressure
  Trawling and overexploitation for commerce directly threaten seagrass beds. Trawling damages habitats, while overexploitation depletes seagrass-dependent species, jeopardizing the health and sustainability of these ecosystems.

Management

• Major seagrass beds should be mapped, and areas identified for preservation.
• Dredging should be carried out away from grass beds to prevent siltation and turbidity, which can harm the beds.

Seaweeds

Seaweeds, macroscopic algae known as thalloid plants, lack true tissues like roots, stems, and leaves.

• Larger, visible marine plants, seaweeds, are attached to rocks, corals, and other submerged surfaces in intertidal and shallow subtidal zones of the sea.
• They thrive in shallow coastal waters wherever sizable substrata is available.
• Seaweeds are broadly classified into different classes based on the color of their pigmentation: blue-green, green, brown, and red.

Functions of Seaweeds

• Food for marine organisms.
• Habitat for fish breeding grounds.
• Source of sediment.

Uses of Seaweeds

• Important as food for humans, feed for animals, and fertilizer for plants.
• Used as a drug for goiter treatment, intestinal and stomach disorders.
• Commercially valuable products like agar-agar, alginates, and iodine are extracted from seaweeds.
• Biodegradation of seaweeds can produce economically important gases like methane.
• Some seaweed extracts exhibit antibacterial activity.
• Used as potential indicators of pollution in coastal ecosystems, particularly heavy metal pollution, due to their ability to bind and accumulate metals strongly.

Harmful Effects of Seaweeds

• Rotting seaweed is a potent source of hydrogen sulfide, a highly toxic gas, implicated in some incidents of apparent hydrogen-sulfide poisoning, causing vomiting and diarrhea.

 Threats to Seaweeds

• Environmental Threats

   Eutrophication, siltation, and coastal engineering harm seagrass beds. Eutrophication leads to algal blooms, siltation reduces sunlight penetration, and coastal constructions disrupt natural habitats.

• Human-Induced Pressure
  Trawling and overexploitation for commerce directly threaten seaweeds . Trawling damages habitats, while overexploitation depletes seagrass-dependent species, jeopardizing the health and sustainability of these ecosystems.