chapter 14 part 1 coral reefs classification biology diversity feeding/nutrition
TRANSCRIPT
Chapter 14Part 1
Coral Reefs
ClassificationBiology
DiversityFeeding/Nutrition
Coral Classification
• Domain: Eukaryota• Kingdom: Animalia• Phylum: Cnidaria (Hatschek, 1888)
• Class: Anthozoa (Ehrenberg, 1831)
Scleractinian Corals
• Calcium carbonate skeleton (CaCO3)• Polyps• Symbiodinium sp. (zooxanthellae)• Hermatypic –
– Contain Symbiodinium– Reef-building
• Ahermatypic– Most do not contain Symbiodinium– Not reef-building
Coral Classification
Coral Biology
Figure 14-2. Cutaway view of one of the polyps in a coral colony and of the calcium carbonate skeleton underneath.
coenosarc
Coral Biology• Radial symmetry• One opening (mouth)• Gastrodermis – tissue
lining stomach• Septum – increase
stomach lining area and contain reproductive cells
• Basal plate - calciferous ring with 6 supporting radial ridges. The ridges grow vertically and project into the base of the polyp.
This drawing depicts the basic anatomy of a hard coral polyp. Artwork Credit: NOAA/Gini Kennedy
Calcium Carbonate Skeletons• CO2 + H20 H2CO3
– (carbonic acid – weak acid)• H2CO3 H+ + HCO3
- – (carbonate ion)
• H+ ion helps to neutralize by combining with OH- to form H20
• Carbonate ion will also:• HCO3
- H+ + CO32- (bicarbonate ion)
• Ca2+ + CO32- CaCO3
• TAKES ENERGY – Where does it come from?
Coral Polyps
Most corals are made up of hundreds to hundreds of thousands of individual coral polyps like these. The tissue is only millimeters thick.
Day
Night
Porites astreoides
Symbiodinium photo by S. R. Santos
Symbiodinium (zooxanthellae) are found in the gastrodermal layer of tissue in the coral at densities greater than 1 million per square inch
Symbiodinium Classification
• Domain: EukaryotaKingdom: ChromalveolataSuperphylum: AlveolataPhylum: DinoflagellataClass: DinophyceaeOrder: SuessialesFamily: BlastodiniaceaeGenus: Symbiodinium
(Freudenthal, 1970)
http://www.eol.org/pages/91312
Symbiodinium• Endosymbionts of cnidarians and giant clams• Provide corals up to 100% of energy for survival
and reef-building– Corals provide wastes that Symbiodinium uses for
photosynthesis.– Symbiodinium provides corals products of
photosynthesis for food• Acquired by corals
– Ingestion by planula– Transmission from mother to daughter colony
through asexual reproduction– Ingestion by coral especially after “bleaching”
Symbiodinium Diversity
Symbiodinium ecological diversity
LaJeunesse, 2001
Typical Coral Growth Forms
Caribbean Corals
Porites astereoides – A4aMontastrea faveolata – B1
Siderastrea siderea – C3 or B5a
Gorgonia ventalina –B1
Acropora palmata – A3
Porites furcata – A4, B1, C4
Indo-Pacific Corals
Acropora hyacinthus
Acropora formosa
Acropora sp. mix
Herpolitha limax
Acropora humilis
Platygyra sp.
Porites sp.
Acropora formosa and Porites sp.
Acropora sp. in the Pacific
Reef Building Corals: Pacific
Coral Nutrition and Feeding
Mesenterial filaments secrete digestive enzymes, corals can also use mucus nets, or absorb DOM from the water
Coral Nutrition and Feeding
Coral Nutrition and Feeding
Love-Hate Relationship with Sunlight
• Necessary for photosynthesis by Symbiodinium• Must protect itself against excess sunlight to avoid “bleaching,” or more accurately, “paling” of Symbiodinium cells • Coral skeleton scatters light to increase absorption when fewer pigments available (Enriquez et al. 2005)
Use of sunlight
GBR1997-1998One of worst
bleaching events in history
Love-Hate Relationship with SunlightProtections against too much sunlight
• Photoprotection• Pigments, pathways of photosynthesis, others
• Coral pigments• Movement of Symbiodinium cells • Diversity of Symbiodinum cells on a single colony
Kemp et al 2008
• Global climate change and coral bleaching– Warmer oceans + high light = stressed Symbiodinium and coralsAND possible death of corals from loss of
Symbiodinium
Coral Bleaching
lh3.ggpht.comwww.ncar.ucar.edu
Coral bleaching video
Coral bleaching
42% of coral cover of GBR lost