Symbiosis between Zooxanthellae & Corals
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Transcript Symbiosis between Zooxanthellae & Corals
Symbiosis between
Zooxanthellae & Corals
By
Mark Mergler
What are Zooxanthellae?
Unicellular yellow-brown dinoflagellate
algae which live in the gastrodermis of
corals
Provide corals with food in the form of
photosynthetic products
Live in coral’s tissues at a density of
1million cells/cm²
Due to need for light, they only live in
ocean waters <100 m
Recently found that there are 10 different
species that live in corals
http://www.seaslugforum.n
et/factsheet.cfm?base=zoo
x1
http://plaza.ufl.edu/amb168
5/Coral_Reef.html
What are Corals?
Start their lives as free-swimming young
Once they find a hard bottom, they attach themselves
and quickly change into a polyp
Coral polyp splits in 2 and makes an identical copy of
itself
Form a colony and secrete a hard calcium carbonate
skeleton
Each polyp makes a small skeletal cup called a calyx
which aids in feeding
As coral colony grows, it secretes new skeletal material
on top of the old
Over thousands of years of accumulation, a coral reef
is formed
http://www.seasky.org/reeflife/sea2b.html
Symbiotic Relationship
between the Two
Zooxanthellae
Provide Corals with food in the form of
organic matter
Corals
Provide zooxanthellae a safe place to live
Excrement is taken in by dinoflagellates
and are recycled
Fringing Reefs
Simplest & most common type
Develop near shore throughout tropics
Occurring close to land makes them
vulnerable to sedimentation, freshwater
runoff, and human disturbance Consist of
An inner reef flat
An outer reef slope
http://plaza.ufl.edu/amb1685/Coral_Reef.html
Barrier Reefs
Much further from shore than
fringing reef
Consist of
A back-reef slope
A reef flat
A fore-reef slope
Most coral growth occurs on the
fore-reef slope
http://plaza.ufl.edu/amb1685/Coral_Reef.html
Atoll
Ring of reef that form from sinking
volcanoes
Usually have a central lagoon
Can rise up from depths of thousands
of meters or more
Occur mostly in the Indo-west Pacific
region
http://plaza.ufl.edu/amb1685/Coral_Ree
f.html
Coral Bleaching
Occurs when corals undergo stressful
situations
White calcium carbonate skeleton is exposed
when corals expel their zooxanthellae
Never a total elimination, (60-90%) remain
Is possible for corals to come back as long as a
substantial amount of time has not passed
Normal environmental conditions must return
If conditions do not return, host corals will
perish
http://www.marinebiology.org/coralbleaching.htm
http://www.marinebiology.org/coralbleaching.htm
Climatic Change / Human
Impact
Climatic change
Increase in temperature
Violent weather
Increased UV exposure
Human impact
Oil pollution
Coral mining
Overfishing
Sedimentation
Nutrient enrichment
References
Brown, B. E. 1997. Disturbances to reefs in recent times. Pages 354-379 in Life and Death
of Coral Reefs, edited by C. Birkeland. Chapman & Hall, New York, NY.
Graham, Linda E., and Lee W. Wilcox. Algae. Upper Saddle River, NJ: Prentice Hall, 2000.
Hughes, Terry P. “Climate Change, Human Impacts, and the Resilience of Coral Reefs”
Science. 301.5635 (2003) 564-576.
Muller-Parker, G., and C. F. D’Elia. 1997. Interactions between corals and their symbiotic
algae. Pages 96-113 in Life and Death of Coral Reefs, edited by C. Birkeland. Chapman &
Hall, New York, NY.
West, Jordan M., and Rodney V. Salm. “Resistance and Resilience to Coral Bleaching:
Implications for Coral Reef Conservation and Management.” Conservation Biology. 17.4
(2003) 956-967.