Lecture #8 - Coral Reef Communities Flashcards
where do coral reefs occur?
nutrient-poor waters (surprising)
what forms the basis of a coral reef community?
symbionts and algae
what kind of species are coral?
foundation species; they enhance the ability for other species to survive and thrive
Scleractinian corals
stony or hard corals, deposit CaCO3 that composes coral reef structure
hermatypic corals
form of scleractinian coral that produce reefs by depositing hard calcareous material for their skeletons; mostly colonial, most have zooxanthellae
ahermatypic corals
non-reef-building species; most do not have zooxanthellae and deposit less calcium carbonate
types of reefs
fringing, barrier, atoll
fringing
develop along tropical/subtropical shores, most affected by human activities due to proximity to land
barrier
separated from the landmass
atoll
circular reef enclosing a lagoon
how much biodiversity are coral reefs responsible for?
about 1/3 of described marine species of all types have been associated with coral reefs
major factors influencing reef distribution
Temperature
Light availability
Sediment accumulation
Salinity
Freshwater outflow
Wave action
Duration of air exposure
2 sources of nutrients for corals
stinging cells (nematocysts)
zooxanthellae perform photosynthesis
cnidocyte
an explosive cell containing one giant secretory organelle, the nematocyst
two tissue layers
gastrodermis and ectodermis
where are zooxanthellae found?
in gastrodermis
symbiotic relationship between zooxanthellae and corals
Zooxanthellae provide glucose, glycerol, and amino acids; in exchange, the coral polyp provides shelter and habitat from external environment, and nitrogen
