59: Coral Bleaching

Question 1

What are corals?

Answer 1

belong to Phylum Cnidaria (like hydras and jellyfish)
- sessile (don’t move) and live in colonies
- about 900 different species

Question 2

What is a coral polyp?

Answer 2

a little bag/sac

Question 3

What do coral larvae do?

Answer 3

not sessile, it moves/swims and then affixes at some point

Question 4

What is the process of corals?

Answer 4

1. corals take calcium dissolved in sea water and use it to build a skeleton of calcium carbonate
2. as coral die, the new generation build a skeleton on top of the dead coral skeleton
3. polyps and their skeletons build a permanent structure that is called a coral reef

Question 5

What is a coral reef?

Answer 5

places of enormous biodiversity that is home to many different species
- rain forest of the seas

Question 6

What is the relationship between corals and zooxanthella?

Answer 6

corals live in a symbiotic, mutualistic relation with a type of algae called zooxanthella
- algae perform photosynthesis and provide the corals with food and help them build their skeletons
- corals give algae a place to live inside their body

Question 7

What are two types of coral reefs?

Answer 7

1: warm-water coral reefs
2: cold-water coral reefs

Question 8

What are warm water coral reefs?

Answer 8

on shallow, sunlit, warm and alkaline (basic) waters
- ex: coral reef from the Great Barrier Reef, Australia

Question 9

What are cold water coral reefs?

Answer 9

found in deeper waters and receive less light
- ex: community from the Mississippi Canyon at 450m depth

Question 10

What is coral bleaching?

Answer 10

when corals are under heat stress, they expel the symbiotic algae

Question 11

What did symbiotic algae do?

Answer 11

give the corals their color, when they are expelled, the corals look bleached
- corals receive less food without the algae

Question 12

What is a bleached coral?

Answer 12

a weakened coral

Question 13

Is coral bleaching a new phenomenon?

Answer 13

no, this has occurred in the past however, events are occurring more often and with more intensity

Question 14

What human activities that act at the LOCAL level threaten coral reefs?

Answer 14

• pollution
• coral harvesting
• overfishing

Question 15

What are cold-water reefs also being affected by?

Answer 15

• fossil fuel exploitation
• sea mining
• pipelines
• cables
• trawling

Question 16

What human activities that act at the GLOBAL level threaten coral reefs?

Answer 16

climate change and ocean acidification

Question 17

What is climate change causing?

Answer 17

• warmer waters (primary cause of bleaching)
• rising sea levels (changes the amount of sunlight)
• more intense storms (more wave action)

Question 18

How does ocean acidification affect coral reefs?

Answer 18

higher CO2 in atmosphere results in lower pH levels in seawater, which in turn reduces calcification rates

Question 19

What can the corals do?

Answer 19

1. adaptation
2. acclimatization
3. range-shift

Question 20

What is adaptation?

Answer 20

natural selection may act and in the long run, more tolerant species and more tolerant individuals within a population may replace the less tolerant

Question 21

What is acclimatization?

Answer 21

corals may shift to more heat resistant zooxanthella

Question 22

What is range-shift?

Answer 22

migration to higher latitudes or deeper waters

Question 23

What can humans do?

Answer 23

stop adding CO2 to the atmosphere and reduce local stress

Question 24

What does reducing local stress involve?

Answer 24

1. ban fishing and trawling and mineral extraction to protect cold-water corals
2. reduce pollution, overexploitation, and damage to coastal areas
3. prevent the establishment of invasive species

Question 25

What is the ecological importance of corals?

Answer 25

habitats for many species

Question 26

What is the economic importance of corals?

Answer 26

1. tourism is important
2. fisheries
3. a lot of people live in coastal areas and depend on corals