Coral Reefs  Why are coral reefs only found in clear shallow water?

The zooxanthellae they have in their tissues require light for photosynthesis

Corals      Polyp stage only; no medusa stage Sexual and asexual reproduction Planula larva

Dinoflagellates live in the endoderm of hermatypic corals. These contribute to their hosts nutrition and metabolism. Without these symbiotes the corals cannot grow fast enough to build reefs. This limits reefs to shallow water.

What is Coral Bleaching?

When corals expel their zooxanthellae  Long term exposure to high temperatures stimulates bleaching  El Nino conditions stimulate bleaching

1.

Fringing Reef 2.

Barrier Reef 3.

Atoll

Structure of a Fringing Reef 1. Reef flat 2. Reef crest 3. Reef slope 2.

1.

3.

What part of the reef has the densest cover and the highest species diversity?

The reef slope

Structure of a Fringing Reef 2.

1.

3.

What part of the reef has the most stressful conditions for organisms that inhabit it?

The reef flat

What fish is this? Damselfish     Graze on seaweeds inside territories Gardeners: weed out unpalatable algae Algal growth thicker within territories than outside High density of cyanobacteria and other nitrogen fixers inside territory

What fish is this? Parrotfish • Teeth form parrot-like beak to nibble on hard corals.

• They grind the corals exoskeleton to get to the algae within the coral and defecate sand.

•Can defecate 5 tons of sand per year.

What fish is this?

Anemone Fish with Host Anemone

Cleaners: Wrasses and Gobies • Some wrasses set up cleaning stations along the reef.

• When a larger fish aligns itself at one of these cleaning stations, a cleaner wrasse removes the parasites from the fish Cleaner Wrasse

Threats to Coral Reefs      Human expansion and development   Deforestation Erosion Siltation Sewage treatment facilities Eutrophication Over fishing Pollution Tourist Gift Trade Aquarium Trade – Cyanide; Explosives