Coral Reef Formations

Coral Organisms

•Corals are made up of individual polyps

•Polyps form colonies

•Hermatypic corals build reefs

•Polyps secrete a calcium carbonate

skeleton

Zooxanthellae

Coral Organisms

•Cnidarians

•Nematocysts

Photosynthesis

Fixed carbon

Branching versus Boulder Corals

Reef formation

• Fringing Reef

• Barrier Reef

• Patch Reef

• Apron Reef

• Bank Reef

• Ribbon Reef

• Atoll Reef

• Table Reef

Largest biological

constructions on earth!

Reef formation

Fringing Reef

-a reef that is directly attached to a shore or

borders it with an intervening shallow channel or

lagoon.

Barrier Reef

- a reef separated from a mainland or island

shore by a deep lagoon

Patch Reef

- an isolated, often circular reef, usually within a lagoon or embayment.

Apron Reef

- a short reef resembling a fringing reef, but more sloped; extending out and downward from a point or peninsular shore.

Bank Reef

- a linear or semi-circular shaped-outline, larger than a patch reef.

Ribbon Reef

- a long, narrow, somewhat winding reef, usually associated with an atoll lagoon.

Atoll Reef

- a more or less circular or continuous barrier reef extending all the way around a lagoon without a central island.

Table Reef

-an isolated reef, approaching an atoll type, but without a lagoon.

Island Reef Formation

Reef Zonation

Reef morphology

Spur and Groove formation

Coral Ecosystems

•Oligotrophic systems

•Low nutrients lead to symbioses

•Important nurseries

•Protection from predation

Highest biodiversity of any

ocean ecosystem!!!

http://www.youtube.com/watch?v=5d3qie3jbHk

Threats to Corals

•Bleaching

•Stressed corals expel zooxanthellae

•Corals already live at their thermal maximum

Predictions for temperature

increases are between 2 and

11.5o F!!!

Threats to Corals

•Sea Level Rise

•Light attenuates with depthPredictions for sea level rise

are between 7 and 23

inches!!!

Threats to Corals

•Overgrowth by macroalgae

•Increased nutrients

•Overfishing of herbivorous fish

•Dieoff of sea urchins

http://www.youtube.com/watch?v=cbN161yBBGA

Phase shifts Coral dominated

reef

Algal

overgrowth

Algal

dominance

-persistent change in two

or more variables

describing a state of

something

Branching versus Boulder Corals

Threats to Corals

•Hurricanes

•Branching Corals

•Shallow-water corals

Sea Level Rise

•Why would corals be good indicators of past sea level

rise and fall?