Reefs Formation and Growth I

The Environment of the ReefNutrient supply:1. Oligotrophic environment- nutrient poor

• Shallow waters where most reefs develop

• Low abundance of food• Hermatypic corals need symbiont

2. Eutrophic- nutrient rich• Dominated by phytoplankton production• Reduces light for coral symbiont• Not necessarily beneficial

Oligotrophic vs Eutrophic

                                       

Limiting factors for reef development:1. Temperature

• 18-32oC2. Light

• Symbiont• Corals thrive in shallow waters where

light intensity is the strongest• Hermatypic corals <30m

3. Salinity• Ave 35 ppt• 28-38 ppt; corals have a difficult time

developing at extreme salinity

• Framework Building

• Sediment Production

• Cementation

• Scleractinian Corals

• Non-Scleractinian Corals

• Coraline Algae

Scleractinian Coral Framework Builders

Non-Scleractinian Coral Framework Builders

fire coral

Coralline Algae Framework Builders

Other Framework

Builders

giant clam

• Fragmented Coral and Coraline Algae

• Foraminifera Skeletons• Halimeda “Dust”• Sponge Spicules• Other Skeletal Debris• Inorganic Precipitation

Reef Sediments: Foraminifera

Reef Sediments: Halimeda SandReef Sediments:

Halimeda Sand

Reef Sediments: Sponge Spicules

Reef Sediments: Other Skeletal Remains

cone shell