Coral Reefs

Why are coral reefs only found in clear shallow water?

The zooxanthellae they have in their tissues require light forphotosynthesis

Corals Phylum _________

Class ___________ Polyp stage only; no medusa stage Sexual and asexual reproduction Planula larva

Cnidaria

Anthozoa

____________ in Soft Coral 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.

Zooxanthellae

What is Coral Bleaching?

Long term exposure to high temperatures stimulates bleaching

El Nino conditions stimulate bleaching

When corals expel their zooxanthellae

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2.

3.

Fringing Reef

Barrier Reef

Atoll

Structure of a Fringing Reef

1.

2.

3.

1. Reef flat 2. Reef crest 3. Reef slope

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

Structure of a Fringing Reef

1.

2.

3.

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

What fish is this? 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

Damselfish

What fish is this? • 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.

Parrotfish

Anemone Fish with Host Anemone

What fish is this?

Cleaners: Wrasses and Gobies

Cleaner Wrasse

• 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

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