A significant study conducted by the Indian National Centre for Ocean Information Services (INCOIS) has identified nine key algal bloom hotspots along India’s east and west coasts.

Key Highlights of the Findings

• Key Algal Bloom Hotspot: Nine algal bloom hotspots have been identified along India’s east and west coasts:
  • West Coast: Goa, Mangaluru, Kozhikode, Kochi, and Vizhinjam Bay.
  • East Coast: Gopalpur, Kalpakkam, Palk Bay, and the Gulf of Mannar.

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• Geographic Patterns of the Algal Bloom:
  • The southern coast of India experiences a higher number of algal blooms compared to the northern coast  as southern India’s warmer sea temperatures and high humidity create an ideal environment for phytoplankton proliferation.
    • Industrial and agricultural runoff from coastal cities like Kochi, Kozhikode, and Mangaluru increases nutrient concentrations in coastal waters, encouraging algal bloom formation.
  • On the east coast, blooms occur primarily during the pre-southwest monsoon and at the onset of the northeast monsoon.
  • On the west coast, blooms are observed during and after the southwest monsoon.
• Phytoplankton Biomass Thresholds: Researchers have established region-specific phytoplankton biomass thresholds to identify and classify bloom phases.
• The classification includes four categories: ‘Likely to Bloom,’ ‘Bloom,’ ‘Intense Bloom,’ and ‘Extreme Bloom.’
• Causes of the Growing Algal Bloom Phenomenon Along India’s Coastline
  • Algal blooms result from a sudden surge in phytoplankton, including diatoms and cyanobacteria.
  • The frequency and intensity of these blooms are increasing due to environmental and anthropogenic factors.

About Algal Blooms

• Algal blooms refer to the exponential growth of phytoplankton in water bodies.
• These blooms occur when sunlight and nutrients are abundantly available, leading to rapid reproduction.
• The dense presence of phytoplankton alters the water’s color.
• Red Tide: A red tide is a harmful algal bloom caused by toxin-producing marine microorganisms, often dinoflagellates, discoloring water and harming marine life through oxygen depletion and toxin accumulation in the food chain.

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Causes of Algal Blooms

• Nutrient Flux: Increased nutrient availability due to monsoons and coastal upwelling (the rise of cooler, nutrient-rich water to the surface).
• Eutrophication: The excessive presence of nutrients supports the rapid growth of algae and cyanobacteria.
• Temperature: Algal blooms are more likely to occur in summer or fall but can happen at any time of the year.
• Turbidity: Turbidity, caused by suspended particles and organic matter in water, influences algal growth.
• • When turbidity is low, more light can penetrate the water column, facilitating photosynthesis and algal growth.

Ecological Impact of Algal Blooms

• Oxygen Depletion (Hypoxia): Algal blooms consume excessive oxygen during decomposition, creating dead zones where marine life cannot survive.
• Toxicity: Some harmful algal species produce neurotoxins and hepatotoxins, which poison fish, shellfish, and even humans through seafood consumption.
• Disruption of Food Chains: Blooms can outcompete beneficial phytoplankton, leading to imbalance in marine ecosystems and starvation of higher organisms.
• Economic Losses: Fisheries suffer due to fish kills, while tourism declines due to foul-smelling, discolored waters and beach closures.
• Coral Reef Damage: Certain algal blooms prevent penetration of sunlight leading to coral smothering and bleaching, weakening reef ecosystems that support diverse marine life.

Measures to Reduce Algal Blooms in Indian Coastal Waters

• Enhance Ocean Water Circulation: Use aeration techniques or artificial upwelling to prevent stagnant water conditions that favor algal blooms.
• Regulate Coastal Runoff: Implement rainwater harvesting and stormwater management to reduce nutrient-rich runoff from urban and agricultural areas.
• Control Industrial & Agricultural Discharge: Enforce stricter wastewater treatment policies to limit excess nitrogen and phosphorus entering coastal waters.
• Promote Sustainable Fishing & Aquaculture: Avoid overfeeding in aquaculture farms and ensure responsible waste disposal to minimize organic pollution.
• Restore Mangroves & Seagrass Beds: These ecosystems act as natural filters, absorbing excess nutrients and preventing bloom formation.
• Monitor & Predict Blooms: Use satellite-based remote sensing and bio-optical algorithms to track and mitigate bloom occurrences in real-time.
• Public Awareness & Policy Action: Educate coastal communities and industries on best practices to limit nutrient pollution and prevent HABs.

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National & Global Initiatives to Monitor Algal Blooms

• Global Initiative: UNESCO IOC HAB Programme
  • Helps member states research, predict, and mitigate harmful algal blooms (HABs).
  • Provides training in species identification, toxicity testing, and monitoring strategies.
• National Initiative: INCOIS Algal Bloom Information Service (AIS)
  • Developed to detect and monitor algal blooms in Indian seas, benefiting fishermen, researchers, and marine resource managers.
  • Uses satellite data to provide near real-time information on bloom hotspots, sea surface temperature anomalies, and chlorophyll concentration in key regions like the Arabian Sea, Kerala Coast, Gulf of Mannar, and Gopalpur waters.

About Phytoplankton

• Phytoplankton are microscopic floating plants found in aquatic ecosystems.
• The biomass of phytoplankton is analyzed by measuring chlorophyll-a content.

Chlorophyll and Its Types

• Chlorophyll is the major pigment used by plants for photosynthesis, a process where light energy is converted into chemical energy through organic compound synthesis.
• There are four types of chlorophyll:
  1. Chlorophyll-a: Found in all higher plants, algae, and cyanobacteria.
  2. Chlorophyll-b: Found in higher plants and green algae.
  3. Chlorophyll-c: Present in diatoms, dinoflagellates, and brown algae.
  4. Chlorophyll-d: Found exclusively in red algae.

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Significance of Phytoplankton

• Phytoplankton contribute to over half of the atmospheric oxygen.
• They play a crucial role in reducing global warming by absorbing human-induced carbon dioxide.
• They serve as the foundation of the oceanic food chain.
• Their abundance acts as a bioindicator for assessing ocean health and ecosystem stability.

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