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Coral Reefs Built entirely by biological activity CaCO 3 solubility low above 20 o isotherm Radioactively labeled Ca absorption low on cloudy days Global.

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Presentation on theme: "Coral Reefs Built entirely by biological activity CaCO 3 solubility low above 20 o isotherm Radioactively labeled Ca absorption low on cloudy days Global."— Presentation transcript:

1 Coral Reefs Built entirely by biological activity CaCO 3 solubility low above 20 o isotherm Radioactively labeled Ca absorption low on cloudy days Global distribution limited by temperature 70 m is max depth (1-2% surface illumination) 32-35 ppt salinity range Limited by sediment & exposure to air (subtidal) Enhanced by wave action to a point

2 Terminology/Taxonomy Hermatypic: Reef building Prop/support Order: Scleractinia HardRay or beam Domain: Eucarya Kingdom: Animalia Phylum: Cnidaria (Coelenterata) Class: Anthozoa Flower animal No medusa stage (only polyp) All marine Solitary or colonial Polar and tropical Some supported by skeleton Largest class of Cnidarians

3 Two-Way Digestive System Cnidarian body plan

4

5 Dinoflagellates Classification is changing: Used to be in Kindom: Protista Now some taxonomists put them in a Kingdom or Phylum : Alveolata (Bauman 2007). Both fresh water & marine Many are bioluminescent Cause Red Tide Some produce neurotoxins Pfiesteria has gotten a lot of press in NC

6 Zooxanthellae apparently loose (or they adhere to the cell wall) their flagella when they live in corals.

7 Zooxanthallae is a genus among the Dinoflagellata It will loose its flagella and live in the tissue of corals Xenia sp. host with its Zooxanthallea sp. endosymbiont Zoanthus sociatus has zooanthallae as intracellular endosymbiont and uses photosynthate and feeds on other zooplankton too. Uses autotrophy & heterotrophy (mixotrophic) (Trench 1974) Giant clam (Tridacna sp.) both digests and uses photosynthate from zooxanthallae Zooxanthallae exist as endosymbionts in bivalves, other coelenterates & gastropods

8 Coral reefs found in waters with notoriously low productivity. Open Tropical Seas produce 18-50 gC/m 2 /yr (Nybakken 1988) Vs. Coral reefs :1500-5000 gC/m 2 /yr (Kohn & Helfrich (1957), Odum & Odum (1955), Johannes et al. (1972) How can this be? Coral reefs, like tropical rain forests hold on to nutrients. Both exist in nutrient POOR Regions. Zooxanthellae live IN coral polyp tissue, thus their photosynthate (carbon compounds) remains in the tissue and does not diffuse in the surrounding sea water. Since polyps are predatory, they capture plankton that float in from the ocean and HOLD the nutrients and support the zooxanthellea nutritionally. Mutualistic Relationship (+/+)

9 How do the coral & and the Zooxanthallae do this? Mutualism: Host & tenant ? both must benefit Predation : Predator & prey ? sometimes “host” digests “tenant’ Parasitism: Host and parasite? Zooxanthallae use lipids captured by coral for their uses Corals may eject Zooxanthallae Changes with species of coral, environmental conditions, and possibly with species of Zooxanthallea

10 Food: Plankton Carnivory by the coral polyp Lipids in prey Light Photosynthesis by Zooxanthallae sp. Carbohydrates to generate ATP Acetyl -CoALipids Lipids constitute 1/3 dry weight of corals (excluding skeleton) Levinton 1982 Saturated fatty acids most common in shallow reefs Unsatured fatty acids increase with depth

11 Long tentacles, catch many plankters, few Zooxanthallea Short tentacles, catch few plankters, many Zooxanthallae Large surface area, many zooxanthallae Low SA, Few Zooxanthallae

12 Atoll formation Sea level Fringing Reef Time Barrier Reef: Larger geologic feature. Pierced by numerous channels “large” lagoon between reef and continent. Ex: Australia, Bahamas

13 Rate of submergence= S Rate of coral growth=CG If S>CG; guyot is formed

14 WIND Sedimentation Low wave action: sediment settles Diminished Coral Growth: Lagoon formation High wave action Little sedimentation High plankton abundance (from ocean) High light: Rapid coral & coralline algae growth Balanced by wave destruction lagoon

15 Darwin 1842 Levinton 1982 Wind & Waves Windward Leeward Surge channels Spur & Buttress Zone No surge channels Branching corals

16 Nybakken 1988

17 Atlantic vs. Pacific Reefs Few atolls Many atolls Corals 36 Genera80 Genera 62 Species700 Species Acropora sp. Dominant reef builder 3 species 200 species Same trends for molluscs, crustaceans, fish

18 Balance of Accretion & Subsidence Acropora cervicornis Staghorn coral Can grow 10 cm/yr Montastrea annularis 0.25-0.7 cm/yr Wave damage Rapid sea level rise Boring animals Sponges Bivalve molluscs Polychaetes Gnawing fish Echinoderms (Acanthaster sp.) 160-206 tons CaCO 3 /yr/ha Defecation of CaCO 3 : “Sand”

19 Complex Species Interactions Direct effects Indirect effects

20 Algae + - Corallivorous Fish - Acropora sp (fast growing)Montastrea sp. (slow growing) Damselfish (Pomacentridae) - - - Remove damselfish, coral gets grazed down Return damselfish Acropora sp. grows back faster than Montastrea sp. Chaetodon capistratus Foureye butterfly fish

21 http://www.mbari.org/staff/conn/botany/reds /ian/default.htm Crustose coralline red algae (Rhodophyta) http://coralreef.noaa.gov/aboutcorals/coral10 1/symbioticalgae/ Zooxanthellae sp. Some Web Sites

22 References

23 Bauman, R.W. 2007. Microbiology with diseases by taxonomy. 2 nd Ed. Pearson/Benjamin Cummings Darwin, C. 1842. The structure and distribution of coral reefs. Being the first part of the geology of the voyage of the Beagle. London: Smith, Elder. Johannes, R. El, et al. 1972. The metabolism of some coral reef communities: A team study of nutrient and energy flux at Eniwetok atoll. Bioscience.. 22:541-543. Kohn, A., and P. Helfrich. 1957. Primary productivity of a Hawaiian coral reef. Limnol. Oceanogr. 2(3):241-251 Nybakken, J.W. 1988. Marine Biology: An Ecological Approach, 2 nd Ed. Harper Collins NY, NY Odum, H.T., and E.P. Odum. 1955. Trophic structure and productivity of a windward coral reef community on Eniwetok Atoll. Ecol. Monogr. 25:291-320 Ogden, J.c., and P.s. Lobel. 1978. The role of herbivorous fishes and urchins in coral reef communities. Envir. Biol. Fishes 3:49-63. Trench RK (1974) Nutritional potentials in Zoanthus sociathus (Coelenterata, Anthozoa). Helg wiss Merresu 26:174–216


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