ReefsReefsKinds of buildupsKinds of buildups
Geographic distributionGeographic distribution
Reef requirementsReef requirements
Community: diversity, Community: diversity, environmental mediators, environmental mediators, species of great affectspecies of great affect
The Sensitive ReefThe Sensitive Reef
Reefs and Geologic TimeReefs and Geologic Time
Reef requirements:Reef requirements:1. 1. Coral reefs are rigid structures Coral reefs are rigid structures
above the sea floor. above the sea floor. Keep up with sea level or drownKeep up with sea level or drown
2. Biologically mediated3. Structure and environemtn
Reef requirements:Reef requirements:1. 3-D topography2. Biological Origins and Mediation2. Biological Origins and Mediation
Created by organismsCreated by organismsOrganisms baffle, bind, accrete Organisms baffle, bind, accrete modify modify environmentenvironment
3. Structure and Environment
Reef requirements:Reef requirements:1. 3-D topography2. Biologically mediated3. A complex ecological and physical structure that 3. A complex ecological and physical structure that
exerts control on the environmetexerts control on the environmet
Types of Reefs: FringeTypes of Reefs: Fringe
Edge of landmassEdge of landmassContinents, islandsContinents, islands
High energy from wavesHigh energy from waves
Small lagoon, if anySmall lagoon, if any
Types of Reefs: BarrierTypes of Reefs: Barrier
““Mature” fringe reef without landmassMature” fringe reef without landmass
Kept up with sea level rise Kept up with sea level rise appears far away from shore appears far away from shore
Large, ecologically rich lagoon between reef and landLarge, ecologically rich lagoon between reef and land
Also formed from fringe reefsAlso formed from fringe reefsRing structure from sunken island Ring structure from sunken island
(subsidence or sea level rise)(subsidence or sea level rise)Reef with internal lagoon, no land massReef with internal lagoon, no land mass
Types of Reefs: AtollTypes of Reefs: Atoll
Types of Reefs: PatchTypes of Reefs: Patch
Often in lagoon behind barrier, atollOften in lagoon behind barrier, atollLow energy environmentLow energy environment
Differentiated from surrounding biota by:Differentiated from surrounding biota by:3-D topography3-D topographyBiological mediationBiological mediationStructure and environmentStructure and environment
Types of Reefs: Types of Reefs: ManmadeManmade
Accidental…Accidental…(industry, pollutants, wrecks)(industry, pollutants, wrecks)
……Or intentionalOr intentional
Tropical Reefs around the Tropical Reefs around the WorldWorld
Biodiversity in Tropical Biodiversity in Tropical ReefsReefs
High light intensity: very low turbidityHigh light intensity: very low turbidityzooxanthellae in symbiosis with coralszooxanthellae in symbiosis with corals
Warm T: between 20-30CWarm T: between 20-30C
Constant salinityConstant salinity
Nutrients: upwelling, other inputNutrients: upwelling, other inputBUT: nutrient poor waters in reefBUT: nutrient poor waters in reefVery tightly recycledVery tightly recycled
Constant currentsConstant currents
Tropical reef Tropical reef requirementsrequirements
Communities 1Communities 1
Very diverse, highest diversity community in the worldVery diverse, highest diversity community in the worldClimax communityClimax community
High degree of niche specializationHigh degree of niche specializationResources very finely partitionedResources very finely partitioned
Bafflers: corals, spongesBafflers: corals, sponges
Guilds that Mediate Guilds that Mediate EnvironmentEnvironment
Bafflers: corals, spongesBinders: microbes, coralline algae, bryozoansBinders: microbes, coralline algae, bryozoans
Guilds that Mediate Guilds that Mediate EnvironmentEnvironment
Bafflers: corals, spongesBinders: microbes, coralline algae, bryozoansBuilders: coralsBuilders: corals
Guilds that Mediate Guilds that Mediate EnvironmentEnvironment
Bafflers: corals, spongesBinders: microbes, coralline algae, bryozoansBuilders: coralsEroders: parrot fish, echinoidsEroders: parrot fish, echinoids
Guilds that Mediate Guilds that Mediate EnvironmentEnvironment
Communities 2Communities 2Recruitment between reefs and within a reefRecruitment between reefs and within a reef
Indo-Pacific reefs: highest diversityIndo-Pacific reefs: highest diversity““Oldest” reef?Oldest” reef?Leftover from Tethys?Leftover from Tethys?
The Fragile ReefThe Fragile ReefReefs in very fragile balanceReefs in very fragile balance
Algae overgrowth and echinoids, other grazersAlgae overgrowth and echinoids, other grazersSpecialists: higher extinction possibilitySpecialists: higher extinction possibilityInteractions fairly tightInteractions fairly tightSpecies of great effect, keystone speciesSpecies of great effect, keystone species
Physical factors:Physical factors:Sea-level riseSea-level riseT and global warmingT and global warmingNutrient input and algal bloomsNutrient input and algal bloomsSaharan dust and fungusSaharan dust and fungus
Earliest buildups: Earliest buildups: Precambrian stromatolitesPrecambrian stromatolites
Early Cambrian: Early Cambrian: Archaeocyathid reefs: Archaeocyathid reefs: 500MY500MY
Devonian: Tabulate, Devonian: Tabulate, rugosa coral reefsrugosa coral reefs
Permian: Capitan sponge Permian: Capitan sponge reef in TXreef in TX
Cretaceous: VariousCretaceous: Various
Cenozoic: coral reefsCenozoic: coral reefs
Geologic History of Geologic History of ReefsReefs