Hard Corals (Stony Corals)

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.

• 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:

• 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.

• 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:

• 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.

• 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:

• 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%).

• 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%).