Transcript Coral Reefs Introduction • Calcium carbonate (CaCO3) anyone?? • Limestone is left over when animals grow and die. • This carbon containing molecule is.

Coral Reefs
Introduction
• Calcium carbonate (CaCO3) anyone??
• Limestone is left over when animals grow and
die.
• This carbon containing molecule is the basis for
coral formation.
• As we will see, coral production exhibits huge
impacts on ecosystem diversity and success.
Requirements for Reef Formation
•
High Light Levels
•
High Water Transparency
•
Water Temperatures > 20°C (68°F)
•
Low Nutrient Waters
•
Hard Substrate for Attachment
•
Good water circulation
Coral Types:
• Hard (Stony, scleractinian, “true”) corals build
the reef by extracting calcium carbonate from the
ocean water.
• They create a home in which primary producers
can live.
• They create a diverse 3-D space in which many
other organisms can find homes.
What is Coral?? Animal, Vegetable, Mineral?
Rem: Coral are actually a special group of cnidarians, the
same family as jellyfish!!
Hermatypic vs. Non-Hermatypic Corals
• Hermatypic Corals (a): Corals that form large
colonies called reefs.
a. brain coral (Diploria)
b. Mushroom coral (Fungia)
• Ahermatypic Corals (b): Corals that are solitary
or form small colonies (often lack zooxanthellae
and do not help build reefs).
Coral larva are called planula, since they don’t like soft
sea floors, they often metamorphose into a polyp which
establishes a founder colony in a new location.
Medusa’s are a mobile polyp.
Boulder coral Montastrea cavernosa
Coral remain closely connected.
Zooxanthellae, single-celled photosynthetic
algae work within the coral to help feed it
through photosynthesis.
As a result of this symbiotic
relationship, many corals
don’t need to seek food.
This added nutrition also
helps corals to build reefs
much faster!
microscopic view of zooxanthellae)
Mutualism Between Corals and Zooxanthellae
• Coral Polyp
• Provides a home for the zooxanthellae.
• Provides nitrates and phosphates.
• Gives off CO2.
Here is a good example of a live coral.
Obviously, the one on the left needs help!!
Coral take on many shapes!!
Reefs grow when calcium
containing sediments are
deposited in spaces between coral.
As encrusting coraline algae
“glues” the sediments together,
new “live rock” is formed.
Coral benefits from the death of other organisms.
Once this Halimeda(calcareous green algae) dies, 95%
of what remains will be sediment and real estate for new
coral colonies.
Coral exhibit limited range in growth patterns.
Without proper
light and temperature,
coral dies (bleaches).
It only takes 1-2 degrees
in some cases.
How does global warming
effect this trend?
From this…
To this….
Temperature increases and competition from red algae have killed
much of this coral reef.
Coral Reefs Have High Primary Productivity
• Coral Reef primary production ranges from 1500
to 3700 g of C/m2/yr.
• This makes Coral Reefs one of the most
productive communities on earth!
• Rapid nutrient cycling between zooxanthellae and
corals may be partially responsible for this.
Fringe Reefs: Diving anyone??
Growth on reefs are often limited by tidal action.
Disease is another major factor limiting growth. Here is
an example of elkhorn coral (Acropora palmata) infested
by “white band disease.”
Barrier Reefs
An excellent example of a Pacific barrier reef.
Barrier reef structure can be influenced by
spur and groove formations such as these.
The Great Barrier Reef
Atoll Reefs: Volcanic Left-overs!
Atoll Reef Fulanga
Atoll Formation: Step by step
Reef Ecology: Edge effect again…
Food Webs: Same concept, more complexity
Coral Fights??
Yes!
Just like other animals competing for space, coral attack
each other if they come into close contact.
Usually they just over grow one another, but some actually
poison the others out!
Again, we see that real estate is at a premium with these
soft corals. Soft corals are fast growers, making them
excellent competetors.
Harmony? Not really, most animals on reefs
compete daily for everything, from food to mating
opportunities.