Coral Reefs Oasis of the Sea Coral Reefs

Coral Reefs Why are coral reefs unique? Coral Reefs

Coral Types Hermatypic Ahermatypic Both groups belong to the phylum Cnidaria Coral Reefs

Coral Structure & Anatomy Coral Reefs

Coral Reproduction Coral Reefs

Coral Nutrition Zooxanthellae provide nourishment for the coral through photosynthesis Polyps eat and are voracious predators on zooplankton Coral Reefs

Other Reef Builders Corals do not build a reef alone Coralline algae produces a skeleton of calcium carbonate that grows in hard sheets on the surface of the reef Coral Reefs

Conditions Needed For Reef Growth Temperature All reefs are bounded by the 20 C isotherm Optimal reef development occurs at 23-25 C and up to 36-40 C Water temperature that is too warm will cause coral bleaching The zooxanthellae is expelled from the coral El Nino events cause massive bleaching in some areas (1997-98) Coral Reefs

Coral Reefs

Light Zooxanthellae dependent corals do not develop in water deeper than 50-70 meters This limitation occurs due to photosynthetic requirements Coral Reefs

Salinity and Sedimentation Corals are intolerant of salinities ranging outside of 32-35 ppt Human activities; dredging, mining, logging, and construction increase the amount of sediment and freshwater runoff Sedimentation clogs feeding mechanism and reduces the penetration of sunlight Coral Reefs

Wave Action Usually not a problem due to hard coral exoskeletons Benefits: renews oxygen, removes sediment, brings in new plankton Reefs cannot tolerate extended periods of exposure to air Coral Reefs

Fringing Reefs Coral Reefs

Barrier Reefs Coral Reefs

Atoll Reefs

Coral Reef Ecology Coral reefs are easily the richest and most diverse of all the oceans ecosystems How do these animals interact with each other, what role do they play in the ecosystem? Reefs are found in areas that are usually poor in nutrients, lack phytoplankton and other means of primary production The question is how do these habitats thrive in these nutrient poor waters? Coral Reefs

Nutrient Cycling Coral Reefs

Competition Space is a limiting resource Sessile animals compete for space in interesting ways Fast growers shade out their neighbors Some use mesentery filaments or sweeper tentacles to sting neighbors Coral Reefs

Predation and Grazing Predation Grazing Grazers are very important to the ecosystem since they help keep the algae in check Coral Reefs