Carl Reefs 2

Question 1

What are the critical necessities of coral reefs?

Answer 1

• access to light
• areas of moderate currents
• maintain the positions over long time
• clear water

Question 2

Around which two things do we expect to see corals?

Answer 2

• shallow waters (between 25-60m), often near land

- initially, access to substrate that is fixed in position.

Question 3

in what two broad types can corals be divided?

Answer 3

• atolls

- coastal reefs

Question 4

define atoll

Answer 4

coral reefs found most often in open ocean with no associated geological land masses

Question 5

define coastal reefs, and what are their sub-divisions

Answer 5

• associated with continental or volcanic land masses.

- fringing, barrier reefs

Question 6

how deep can atolls go?

Answer 6

thousands of meters or more

Question 7

where are the majority of atolls found?

Answer 7

indo-pacific

Question 8

what was the name of the battle and atoll that was pivotal in the second wold war?

Answer 8

The battle of Midway. june 1942

Question 9

what are some physical characteristics shared by atolls?

Answer 9

• ring shaped
• sandy lagoons within the reef
• reefs are often open on the windward end, resembling a horseshoe
• often very flat and low elevation

Question 10

what is the name of Darwin’s ship, what year did he discover atolls

Answer 10

HMS Beagle, 1830s

Question 11

explain the timeline it takes for a coral atoll to form

Answer 11

• fringing reef takes 10,000 years
• over 100,000 years reef will expand
• as the interior island subsides beneath the water, it can take up to 30,000,000 years for the atoll to form.

Question 12

what discoveries proved darwin’s theory of the origin of atolls?

Answer 12

• scientists drilled >1400 ft into an atoll before they found volcanic rock
• remnants of dead surface reefs on seamounts show where volcanoes sank too quickly for reefs to maintain contact with light

Question 13

describe fringing reefs and their associated ecology

Answer 13

• found in a band close to the fringe of the shoreline
• consist of an inner reef flat and a reef slope
• inner flat is mostly sandy, muddy, and has coral rubble
• the shoreline can be home to mangroves

Question 14

how are fringing reefs affected from terrestrial elements?

Answer 14

• freshwater runoffs
• terrestrial erosion
• more extreme temperature variations
• prolonged exposure during low-tides

Question 15

how are fringing reefs and barrier reefs different?

Answer 15

• barrier are much further offshore
• their lagoons are much larger and deeper
• extensive reefs on the inner shore of barrier as well as outer

Question 16

what accounts for the great diversity and zonation of corals foud in coral reefs?

Answer 16

• difference in environmental conditions:
• salinity
• turbidity
• depth
• gradient

Question 17

what are patch reefs?

Answer 17

small, isolated reefs that grow up from the open bottom of the island platform or continental shelf.

• usually occur between fringing reefs and barrier reefs
• rarely reach the surface water

Question 18

what contribute to the growth of coral reefs?

Answer 18

• ground subsidence

- ocean level changes

Question 19

what is the highest point of the reef called?

-what are some of its features?

Answer 19

• reef crest or breaker zone
• dominated by corals and is often the richest coral area of them all
• can be largely covered by coralline algae depending on reef height and depth and strength of wave action