Nov. 21 / Coral Reefs

What fish is an example of biotic control and ecological service?

Parrotfish

Why is tropical sand white?

Parrotfish feed on algae but take rocks and corals with them, excreting the white calcium sand

What is the coral’s photosynthetic partner?

Zooxanthellae

A coral is made up of many small ___.

polyps

Corals and their partner algae are ___.

mutualists

Who makes the majority of the energy for the coral?

Zooxanthellae

True or false: the coral does not hunt

False

True or false: as coral feed and grow, they lay down skeleton under their tissue

True

Abiotic components of a coral reef

• Temperature

• Sand

• Rock

• Water

• Sunlight

• Salinity

Abiotic environmental conditions must accommodate the coral and ___.

the zooxanthellae

Do cold-water corals have symbiotic algae?

No

Most tropical corals are found in __ degrees north and south from the equator.

30

Is the Atlantic much more diverse than the Pacific?

No, the Pacific is much more diverse.

Upwelling

When winds drive water away from the shore and deeper water replaces it, bringing in new nutrients and phytoplankton, which zooplankton eat, then the fish eat the following, then the killer whales eat the following. Very uncommon

Do corals or seaweeds like high nutrient levels?

Seaweeds. Corals do NOT!

Are corals intolerant or tolerant to wide ranges of salinity?

Intolerant

Corals are osmoconformers, meaning what?

They can only regulate their internal salinity to a certain extent. If outside gets more salty, their internal tissues will match

Where do salts in the ocean come from?

The rocks on land erode and gets to the ocean through soil runoff and then travelling through rivers

What controls salinity in the oceans?

The input of freshwater from rivers can decrease it. But less precipitation and more evaporation can increase it.

True or false: light availability related to photosynthesis of zooxanthallae affects coral calcification rates

True

True or false: most coral reefs are found in coastal areas where there’s more runoff from land and the water is not crystal clear (usually 50m)

True

Why don’t corals like nutrient-rich water?

Because seaweed love it and the corals will be outcompeted

Coral bleaching

When corals lose their zooxanthallae but the living coral tissue remains, which is clear and the skeleton is now visible. The coral is not dead right away

Mass coral bleaching was first observed in the 1980s in the Caribbean, happening every few years. Today, what change has happened that makes coral reefs have less time to recover?

The mass bleaching events are happening much more often, so the reefs can’t recover as well

Are cold-water coral deep or shallow?

Extremely deep

Where are cold-water corals found?

All oceans in all latitudes

How do the cold-water corals eat?

They have no algae, so they rely fully on hunting

When did we discover cold-water corals?

Fishermen have known for hundreds of years, but scientists have just discovered them in the past 20 years

Do cold-water corals like nutrient-rich waters? Why or why not?

Yes! Because they don’t have their algae so they need more nutrients

Which of the following is an outcome if a coral reef were to experience mortality from coral bleaching?

Decrease in protection of coastal areas