TAG: GS 3: ECOLOGY AND ENVIRONMENT
THE CONTEXT: The National Oceanic and Atmospheric Administration (NOAA) recently announced the onset of the fourth global coral bleaching event, marking a significant threat to coral reefs worldwide.
EXPLANATION:
- This event, fueled by record ocean temperatures, underscores the urgency of addressing climate change and its impact on marine ecosystems.
- Coral bleaching occurs when corals expel symbiotic algae in response to environmental stressors such as elevated temperatures, light exposure, or nutrient imbalances.
- This expulsion causes corals to turn white, signaling distress. While corals can survive bleaching events, prolonged stress increases their vulnerability to mortality.
Frequency and Severity
- The current bleaching event is the fourth global occurrence on record and the second within the past decade, highlighting the escalating threat posed by climate change.
- NOAA’s Coral Reef Watch (CRW) monitors heat stress levels, predicting and tracking bleaching events using satellite data.
- Since early 2023, extensive bleaching has been observed across the Atlantic, Pacific, and Indian Ocean basins, affecting coral reefs in various regions.
Global Impact
- The widespread bleaching documented across diverse geographic locations, including Florida, the Caribbean, Australia’s Great Barrier Reef, and the Red Sea, underscores the global scale of the crisis.
- Coral reefs serve as critical ecosystems, supporting biodiversity, coastal protection, and fisheries.
- The degradation of coral reefs due to bleaching poses direct threats to livelihoods, food security, and economies dependent on marine resources.
Long-term Implications
- Climate models predict an increase in the frequency and severity of bleaching events as ocean temperatures continue to rise.
- This trend aligns with the broader pattern of climate change-induced disruptions to marine ecosystems.
- Addressing the underlying drivers of climate change and implementing mitigation strategies are crucial for safeguarding coral reefs and the communities reliant on them.
Scientific Monitoring and Conservation Efforts
- NOAA’s efforts in monitoring and predicting coral bleaching events play a vital role in informing conservation strategies and management practices.
- By utilizing advanced satellite technology and collaborating with international partners, NOAA aims to enhance our understanding of coral reef dynamics and mitigate the impacts of bleaching events.
Coral Reef:
- Coral reefs are vital ecosystems built by coral polyps, which have a symbiotic relationship with zooxanthellae algae.
- When water temperatures rise, corals expel these algae, leading to bleaching—a phenomenon where corals lose their vibrant colors and eventually die.
- Ocean acidification exacerbates bleaching by reducing calcium mineral availability for coral exoskeletons.
Types of coral reefs in India:
- Fringing reefs
- Fringing reefs evolve and develop near the continent and remain close to the coastline. These reefs are separated from the coastline by small, shallow lagoons. They are the most commonly found reefs in the world.
- Barrier reefs
- Barrier reefs are found offshore on the continental shelf. They usually run parallel to the coastline at some distance. A deep and wide lagoon is located between the coastline and the barrier reef.
- Atolls
- Atolls are formed on mid-oceanic ridges. They are shaped circularly or elliptically and are surrounded by seas on all four sides and have shallow waters in the center called a lagoon.
- All the three major reef types occur in India. The mainland coast of India has two widely separated areas containing reefs: the Gulf of Kachchh in the northwest, which has some of the most northerly reefs in the world, and Palk Bay and Gulf of Mannar in the southeast.
- In addition to these, there are patches of reef growth on the West Coast, for example, coral reefs at Malvan.
- The Andaman and Nicobar Islands have fringing reefs around many islands, and a long barrier reef (329 km) on the west coast.
- Little is known about these reefs, which may be the most diverse and pristine reefs in India. The Lakshadweep also has extensive reefs but these are also poorly explored.