India’s Coastlines Face Algal Bloom Threat

January 24, 2025

India’s coastline is facing an alarming rise in algal blooms. These blooms, marked by rapid increases in phytoplankton, are becoming more common due to both natural and anthropogenic factors. A recent study led by T.M. Balakrishnan Nair from the Indian National Centre for Ocean Information Services (INCOIS) has pinpointed nine hotspots for these blooms along the Indian coasts. This research marks the need for better monitoring and management of marine resources.

What Are Algal Blooms?

Algal blooms refer to a sudden increase in algae populations in aquatic environments.
They can occur in both marine and freshwater ecosystems, often identified by noticeable discolouration of the water.
Nutrient enrichment, particularly from nitrogen and phosphorus, typically triggers these blooms.
Algae can be unicellular or multicellular, with various types causing different water colourations.

Causes of Algal Blooms

The primary cause of algal blooms is an influx of nutrients into water bodies. This can result from agricultural runoff, sewage discharge, or other human activities. Natural factors, such as ocean currents bringing nutrients to the surface, also contribute. When sunlight and nutrient levels are optimal, algae proliferate rapidly, leading to blooms.

Types of Algal Blooms

Algal blooms can be classified into two categories – beneficial and harmful. Beneficial blooms can enhance fisheries by providing food for marine life. Conversely, harmful algal blooms (HABs) produce toxins that can disrupt ecosystems. Notable examples include red tides caused by dinoflagellates, which can have severe ecological and health impacts.

Effects of Harmful Algal Blooms

HABs pose threats to marine life and human health. They can cause mass die-offs of fish and other aquatic organisms by depleting oxygen levels and clogging gills. Toxins from HABs can accumulate in shellfish, leading to serious health issues for humans who consume contaminated seafood. Symptoms range from gastrointestinal distress to paralysis.

Key Algal Bloom Hotspots in India

The study identifies nine critical hotspots for algal blooms along India’s coasts – Goa, Mangaluru, Kozhikode, Kochi, and Vizhinjam Bay on the west coast, and Gopalpur, Kalpakkam, Palk Bay, and the Gulf of Mannar on the east coast. About these areas is crucial for monitoring and managing algal bloom occurrences.

Phytoplankton and Bloom Classification

Phytoplankton forms the base of the marine food web. The study introduced specific biomass thresholds for phytoplankton to classify bloom phases into categories such as ‘Likely to Bloom’, ‘Bloom’, ‘Intense Bloom’, and ‘Extreme Bloom’. This classification aids in understanding the severity and potential impact of blooms.

Monitoring Techniques and Future Directions

The research emphasises the need for advanced monitoring methods, including region-specific bio-optical algorithms and enhanced satellite remote sensing. These technologies can improve early detection of algal blooms, allowing for timely interventions to mitigate their effects.

Seasonal Patterns of Algal Blooms

Algal blooms in India show distinct seasonal patterns. The southern coast experiences more frequent blooms, particularly during the pre-southwest and onset of the northeast monsoon. In contrast, the west coast sees blooms mainly during the southwest and post-southwest monsoon periods.

Implications for Marine Ecosystems and Livelihoods

The rise in algal blooms has implications for marine ecosystems and the livelihoods dependent on them. Effective management strategies are essential to ensure the sustainability of fisheries and tourism, particularly in the face of climate change and increasing human activities. About these trends is vital for preserving biodiversity and supporting local economies.

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