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Reefs. Kinds of buildups Geographic distribution Reef requirements Community: diversity, environmental mediators, species of great affect The Sensitive Reef Reefs and Geologic Time. Reef requirements: 1. Coral reefs are rigid structures above the sea floor.
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Reefs Kinds of buildups Geographic distribution Reef requirements Community: diversity, environmental mediators, species of great affect The Sensitive Reef Reefs and Geologic Time
Reef requirements: 1. Coral reefs are rigid structures above the sea floor. Keep up with sea level or drown 2. Biologically mediated 3. Structure and environemtn
Reef requirements: 1. 3-D topography 2. Biological Origins and Mediation Created by organisms Organisms baffle, bind, accrete modify environment 3. Structure and Environment
Reef requirements: 1. 3-D topography 2. Biologically mediated 3. A complex ecological and physical structure that exerts control on the environmet
Types of Reefs: Fringe Edge of landmass Continents, islands High energy from waves Small lagoon, if any
Types of Reefs: Barrier “Mature” fringe reef without landmass Kept up with sea level rise appears far away from shore Large, ecologically rich lagoon between reef and land
Types of Reefs: Atoll Also formed from fringe reefs Ring structure from sunken island (subsidence or sea level rise) Reef with internal lagoon, no land mass
Types of Reefs: Patch Often in lagoon behind barrier, atoll Low energy environment Differentiated from surrounding biota by: 3-D topography Biological mediation Structure and environment
Types of Reefs: Manmade Accidental… (industry, pollutants, wrecks) …Or intentional
Tropical reef requirements High light intensity: very low turbidity zooxanthellae in symbiosis with corals Warm T: between 20-30C Constant salinity Nutrients: upwelling, other input BUT: nutrient poor waters in reef Very tightly recycled Constant currents
Communities 1 Very diverse, highest diversity community in the world Climax community High degree of niche specialization Resources very finely partitioned
Guilds that Mediate Environment Bafflers: corals, sponges
Guilds that Mediate Environment Bafflers: corals, sponges Binders: microbes, coralline algae, bryozoans
Guilds that Mediate Environment Bafflers: corals, sponges Binders: microbes, coralline algae, bryozoans Builders: corals
Guilds that Mediate Environment Bafflers: corals, sponges Binders: microbes, coralline algae, bryozoans Builders: corals Eroders: parrot fish, echinoids
Communities 2 Recruitment between reefs and within a reef Indo-Pacific reefs: highest diversity “Oldest” reef? Leftover from Tethys?
The Fragile Reef Reefs in very fragile balance Algae overgrowth and echinoids, other grazers Specialists: higher extinction possibility Interactions fairly tight Species of great effect, keystone species Physical factors: Sea-level rise T and global warming Nutrient input and algal blooms Saharan dust and fungus
Geologic History of Reefs Earliest buildups: Precambrian stromatolites Early Cambrian: Archaeocyathid reefs: 500MY Devonian: Tabulate, rugosa coral reefs Permian: Capitan sponge reef in TX Cretaceous: Various Cenozoic: coral reefs