coral reefs1 oasis of the sea. coral reefs2 why are coral reefs unique?
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Coral Reefs 6
Coral Nutrition Zooxanthellae provide
nourishment for the coral through photosynthesis Polyps eat and are
voracious predators on zooplankton
Coral Reefs 7
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 8
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)
Conditions Needed For Reef Growth
Coral Reefs 10
Light Zooxanthellae dependent corals do not develop in
water deeper than 50-70 meters This limitation occurs due to photosynthetic
requirements
Coral Reefs 11
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 12
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 16
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 18
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