Source: DTE
Subject: Environment
Context: A new Global Coral Reef Monitoring Network (GCRMN) assessment shows Caribbean hard coral cover has declined by 48% between 1980 and 2024 due to extreme heat and bleaching events.
About Hard Corals (Stony Corals):
- What they are?
- Hard corals (stony corals) are marine animals that secrete calcium carbonate skeletons, forming the rigid structures that make up coral reefs, which support one-third of marine biodiversity.
- Types of Corals:
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- Hard Corals (Reef-Building): Species like elkhorn and staghorn corals; they grow in colonies, produce limestone skeletons, and construct reef frameworks.
- Soft Corals (Non-Reef-Building): Include Sea fingers, sea whips; flexible, plant-like, without stony skeletons, and do not form reefs.
- Key Features of Hard Corals:
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- Build calcium carbonate skeletons that become reef rock over centuries.
- Live in colonies of tiny polyps, each hosting zooxanthellae algae that provide food through photosynthesis.
- Form the foundation of coral reef ecosystems, enabling fish nurseries, coastal protection, and high biodiversity.
- Thrive in warm, clear, shallow waters with stable conditions.
- Threats to Hard Corals:
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- Mass Bleaching Events: Driven by extreme heat waves (1998, 2005, 2023–24), causing coral starvation and mortality.
- Stony Coral Tissue Loss Disease (SCTLD): A fast-spreading disease affecting >30 species, now across 30 Caribbean countries; considered the most devastating coral disease recorded.
- Herbivore Declines: Collapse of sea urchins (Diadema antillarum) and declining parrotfish populations → uncontrolled macroalgae growth (up 85%).
