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Explore the formation and growth of reefs, including the ecological controls and limiting factors. Learn about the role of nutrient supply, light, temperature, salinity, and framework builders in reef development. Understand the processes of reef construction, sediment production, and cementation. Discover the various reef sediments, including fragmented coral, foraminifera skeletons, halimeda sand, sponge spicules, and more.
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Ecological controls over reef development The Environment of the Reef • Nutrient supply: • Oligotrophic environment- nutrient poor • Shallow waters where most reefs develop • Low abundance of food • Hermatypic corals need symbiont • Eutrophic- nutrient rich • Dominated by phytoplankton production • Reduces light for coral symbiont • Not necessarily beneficial
Limiting factors for reef development: • Temperature • 18-32oC • Light • Symbiont • Corals thrive in shallow waters where light intensity is the strongest • Hermatypic corals <30m • Salinity • Ave 35 ppt • 28-38 ppt; corals have a difficult time developing at extreme salinity
Reef Growth = Reef Construction minus Reef Erosion
Reef Construction Process • Framework Building • Sediment Production • Cementation
Principle Framework Builders • Scleractinian Corals • Non-Scleractinian Corals • Coraline Algae
Non-Scleractinian Coral Framework Builders fire coral
Other Framework Builders giant clam
Reef Sediments • Fragmented Coral and Coraline Algae • Foraminifera Skeletons • Halimeda “Dust” • Sponge Spicules • Other Skeletal Debris • Inorganic Precipitation
Reef Sediments: Halimeda Sand Reef Sediments: Halimeda Sand
Reef Sediments: Other Skeletal Remains cone shell