Coral and Mangrove Ecosystems Summary

Types of Coral

• Two general types: Hard corals and Soft corals.
  • Hard corals: more calcified; can form reefs.
  • Soft corals: lack zooxanthellae, do not form reefs.
  • Examples: Sea whips, Sea fans.

Structure of a Coral Polyp

• Key structures of a coral polyp:
  • Tentacles: Capture food & clear debris.
  • Nematocysts: Stinging cells for capturing food.
  • Mouth: Ingests food and expels waste.
  • Calyx: The "cup" where the polyp resides.
  • Theca: Walls surrounding the calyx.
  • Basal plate: Attaches to the rocky substrate.

Nutrition of Corals

• Corals use nematocysts to sting zooplankton and bring them to their mouth.
• Enzymes in the gastrovascular cavity aid digestion.
• Most nutrition derived from glucose produced by zooxanthellae (via photosynthesis).

Importance of Coral Reefs

• Coastal Protection: Absorb and slow waves, reduce erosion.
• Food Source: Critical for millions; supports fisheries.
• Medicine: Research into treatments for various diseases.
• Tourism: Generates significant revenue (~$35 billion).
• Biodiversity: High productivity leads to diverse ecosystems.

Threats to Coral Reefs

• Crown of Thorns Starfish (COT): Overpopulation can devastate reefs.
• Lack of natural predators due to overfishing exacerbates COT outbreaks.

Causes & Effects of Reef Erosion

• Acidic waters (lower pH) dissolve coral skeletons, preventing calcium absorption for structure.