Algal Blooms Impacting India’s Coastal Biodiversity

India’s coastline, known for its rich biodiversity, faces a rising threat from algal blooms. These events occur due to a rapid increase in phytoplankton biomass, influenced by both environmental and human factors. A recent study led by T.M. Balakrishnan Nair from the Indian National Centre for Ocean Information Services (INCOIS) has identified nine algal bloom hotspots along India’s eastern and western coasts.

Key Algal Bloom Hotspots

The identified hotspots are critical areas for monitoring. On the west coast, hotspots include Goa, Mangaluru, Kozhikode, Kochi, and Vizhinjam Bay. The east coast hotspots are Gopalpur, Kalpakkam, Palk Bay, and the Gulf of Mannar. These locations are vital for understanding the dynamics of algal blooms in Indian waters.

Phytoplankton Biomass Thresholds

For the first time, researchers have established specific phytoplankton biomass thresholds for these hotspots. They categorised bloom phases into four distinct classifications – ‘Likely to Bloom’, ‘Bloom’, ‘Intense Bloom’, and ‘Extreme Bloom’. This classification provides a framework for better monitoring and understanding of algal bloom dynamics.

Drivers of Algal Blooms

The study marks several factors contributing to algal blooms. Nutrient flux during monsoon seasons and coastal upwelling are contributors. Coastal upwelling brings cooler, nutrient-rich water to the ocean surface, encouraging phytoplankton growth. Dominant algal species include diatoms, dinoflagellates, and cyanobacteria.

Ecological Implications

Phytoplankton serves as the foundation of the marine food chain. However, unchecked growth can lead to harmful algal blooms (HABs). These HABs can disrupt ecosystems, deplete oxygen levels, and produce toxins that harm aquatic life and human activities, such as fishing and tourism. While some algal blooms can benefit fisheries, HABs pose risks.

Regional Bloom Patterns

The research indicates that the southern Indian coast experiences more frequent blooms compared to the north. On the east coast, blooms primarily occur before the southwest monsoon and during the onset of the northeast monsoon. Conversely, on the west coast, blooms are more common during the southwest and post-southwest monsoon periods.

Need for Advanced Monitoring

The study emphasises the necessity for advanced monitoring techniques. Region-specific bio-optical algorithms and improved satellite remote sensing are crucial for effective bloom detection. About long-term trends and impacts of algal blooms is essential for the preservation of marine ecosystems and the livelihoods they support.

Research Collaboration

The study, titled ‘Determining chlorophyll-a thresholds for characterising algal bloom conditions – An ocean colour remote sensing approach’, was conducted in collaboration with the National Institute of Oceanography (NIO) and Berhampur University. It features contributions from various researchers, including Susmita Raulo and V.V.S.S. Sarma.

Questions for UPSC:

1. Discuss the ecological implications of harmful algal blooms on marine ecosystems.
2. Critically examine the impact of climate change on coastal ecosystems and marine biodiversity.
3. Explain the significance of phytoplankton in marine food chains and its role in algal bloom formation.
4. With suitable examples, discuss the methods used for monitoring algal blooms in coastal waters.

Answer Hints:

1. Discuss the ecological implications of harmful algal blooms on marine ecosystems.

1. Harmful algal blooms (HABs) can deplete oxygen levels, leading to hypoxic conditions that threaten marine life.
2. They produce toxins that can harm fish, shellfish, and other aquatic organisms, disrupting food webs.
3. HABs can negatively affect human activities such as fishing and tourism, impacting local economies.
4. They can alter habitats, reducing biodiversity and affecting species composition in marine ecosystems.
5. Some algal blooms can lead to fish kills, causing ecological and economic repercussions.

2. Critically examine the impact of climate change on coastal ecosystems and marine biodiversity.

1. Climate change leads to rising sea temperatures, which can exacerbate algal blooms and disrupt marine ecosystems.
2. Increased ocean acidification affects calcifying organisms, impacting biodiversity and food chains.
3. Changes in precipitation patterns can alter nutrient runoff, influencing algal bloom dynamics.
4. Sea-level rise threatens coastal habitats, leading to loss of biodiversity in sensitive areas like mangroves and coral reefs.
5. Climate change can shift species distributions, affecting predator-prey relationships and ecosystem stability.

3. Explain the significance of phytoplankton in marine food chains and its role in algal bloom formation.

1. Phytoplankton are primary producers, forming the base of the marine food web and supporting diverse marine life.
2. They play important role in carbon fixation, contributing to global carbon cycles and climate regulation.
3. Nutrient enrichment from runoff can lead to rapid phytoplankton growth, resulting in algal blooms.
4. Different species of phytoplankton, like diatoms and dinoflagellates, can dominate blooms, impacting ecosystem dynamics.
5. About phytoplankton dynamics is essential for predicting and managing algal bloom occurrences.

4. With suitable examples, discuss the methods used for monitoring algal blooms in coastal waters.

1. Satellite remote sensing is used to detect chlorophyll-a concentrations, indicating phytoplankton biomass and bloom presence.
2. In-situ measurements, such as water sampling and analysis, provide detailed information on bloom composition and toxicity.
3. Bio-optical algorithms help interpret satellite data by correlating it with water quality parameters.
4. Modeling approaches can predict bloom occurrences based on environmental conditions and nutrient fluxes.
5. Collaboration with research institutions enhances data collection and analysis, improving monitoring effectiveness.