Lec 14: Case Study - Biotic/abiotic interactions in marine reefs

Question 1

what are coral reefs?

Answer 1

big underwater structures of the skeletons of corals, largest living structure on the planet, rainforest of the sea

Question 2

what are corals?

Answer 2

• animals

- colonial marine invertebrates

Question 3

name the 2 types of corals

Answer 3

hard corals

• produce calcium carbonate
• have rock-like skeleton

soft corals

• produce less calcium carbonate
• don’t produce reefs but live on them

Question 4

which type of corals produce reefs?

Answer 4

hard corals

Question 5

why are reefs important?

Answer 5

• biodiversity
• provide habitats
• protect coastlines from waves and storms
• support marine food chains (source of nutrients)

Question 6

what are the individual coral animals called?

Answer 6

polyps

Question 7

where do coral reefs grow

Answer 7

in shallow tropical and subtropical waters, in waters at 23-29 C and 32-40% salinity

Question 8

where do branching, plate-like corals grow?

Answer 8

in quieter waters

Question 9

why type of coral is photosynthetic?

Answer 9

hard corals are photosynthetic through a symbiotic dinoflagellates living within them

Question 10

what are the two ways corals can feed?

Answer 10

1) dinoflagellates through photosynthesis

2) catching small marine life

Question 11

what is exchanged in the polyps-dinoflagellate symbotic exchange?

Answer 11

algae give: energy and color

polyps give: CO2 and home

Question 12

what is the maximum depth of coral growth? why is it so shallow?

Answer 12

25m because they need sunlight

Question 13

are dinoflagellates hetero or auto trophic?

Answer 13

can be either one (50/50)

Question 14

how long have corals existed?

Answer 14

500 million years

Question 15

what have been the causes of coral extinction?

Answer 15

• warming due to rising CO2 and CH4

- ocean acidification

Question 16

what is the name of the extinction event that took place as Pangea formed? What happened to corals and why?

Answer 16

• ordovician-silurian extinction event
• ocean circulation affected
• sea levels and temp drop
• corals dissapear

Question 17

describe the presence of corals throughout the devonian

Answer 17

devonian reefs were present almost everywhere and were ecosystems, but were wiped out by the late-devonian mass extinction 360 Ma.

Question 18

what are ancient coral reefs now?

Answer 18

tight oil and gas reservoirs

Question 19

what are threats to coral reefs?

Answer 19

• natural phenomena
• local human-imposed threats
• climate change

Question 20

How does coral bleaching occur?

Answer 20

when corals overheat, they respond by expelling their algae. their energy needs are then not met, and they begin to starve.

Question 21

What led to the 2015-16 Bleaching event?

Answer 21

• ocean warming due to climate change

- combined with El Nino

Question 22

How does plastic in the ocean affect corals?

Answer 22

• increases chance of disease in corals

- block sunlight

Question 23

what is formed when co2 dissolves in seawater?

Answer 23

carbonic acid

Question 24

what do corals build their skeletons with?

Answer 24

calcium carbonate

Question 25

what does increased carbonic acid content in seawater do to corals?

Answer 25

• carrying capacity of water for calcium carbonate is lower

- corals cannot build skeleton