Coral Reefs

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Coral Reefs

• Why are coral reefs only found in clear shallow
  water?

The zooxanthellae they have in their tissues
require light for photosynthesis
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Corals
Cnidaria

• Phylum _________
• Class ___________
• Polyp stage only no medusa stage
• Sexual and asexual reproduction
• Planula larva

Anthozoa
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____________ in Soft Coral
Zooxanthellae

• 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.

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What is Coral Bleaching?
When corals expel their zooxanthellae

• Long term exposure to high temperatures
  stimulates bleaching
• El Nino conditions stimulate bleaching

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1.
Fringing Reef
2.
Barrier Reef
Atoll
3.
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(No Transcript)
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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
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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
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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

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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.

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Anemone Fish with Host Anemone
What fish is this?
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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
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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