Coral Reef - Ecological Interactions

Question 1

how do corals reproduce?

Answer 1

brooding and spawning

Question 2

what is brooding?

Answer 2

internal fertilization - retains egg, planula larva is released

Question 3

what is spawning?

Answer 3

release packets of eggs and sperm, fertilization is external - both separate sexes and hermaphroditic species exist
- shoots up into enviro and floats into a column

Question 4

what is used to determine when to spawn?

Answer 4

season - spring or early fall
moonlight - evening and slack tide -> full moon triggers spawning, tides affect the moon, slack tide: brief period between tidal flows
smell - chemicals - pheromones
weather - low wave action

Question 5

why do corals start spawning at different times?

Answer 5

lessen the competition

Question 6

when does sperm lose its viability?

Answer 6

within 30 min of spawning - prevents hybrids

Question 7

what types of corals can form a hybrid?

Answer 7

montastraea annularis and montastraea franksi

Question 8

what is darwin’s paradox?

Answer 8

highly productive but low in nutrients

Question 9

where do corals get nutrients from?

Answer 9

• algal symbionts
• recycling nutrients
• animals feed and excrere
• land plants and birds on atoll
• algae of reef flat
• upwelling of deep water

Question 10

where is diversity the greatest?

Answer 10

indo pacific more than atlantic

Question 11

why are there more habitats?

Answer 11

• competition: leads to specialized adaptations, branch out niches so there is less competition
• lottery: fish are not specialized, local success depends on what is available, what they acquire in order to succeed
• predation-disturbance: disturbance keeps fish pop low, competition not an issue, adds balance, no speecies can overtake the reef
• recruitment limitation hypothesis: larval supply low - adult pop reflects differences in larval supply

Question 12

what is key to keeping algal growth in check?

Answer 12

grazing

Question 13

what animal grazes more selectively than sea urchins?

Answer 13

fish

Question 14

what fish species can let too much algae grow?

Answer 14

damsel fishes

Question 15

what are the challenges for coral reefs?

Answer 15

• crown of thorns starfish “plagues” - digest large areas of reef - overtake the reef, predate and digest reefs
• episodic
• few predators

Question 16

what causes bleaching?

Answer 16

• increased temp
• bacterial infection
• UV
• bleaching reduces immunity and food meaning there is a higher chance of disease
• expel zooxanthellae when they die from stress

Question 17

what happened in 2002?

Answer 17

seawater temp reached highest
54% bleached and of the 54 -> 25% bleached

Question 18

what is protective in zooxanthellae and coral tissue?

Answer 18

fluorescent pigments

Question 19

what are multi-cultures?

Answer 19

species are acclimated to diff light levels
- diff corals have diff tolerances to bleaching
- variability in bleaching is due to diff species of algae in tissue
- spit out algae that are dying so tolerances change

Question 20

what dissipates excess energy at benign wavelengths?

Answer 20

FPs
- diffuse harmful light at less harmful wavelengths
- mostly blue

Question 21

what is pocilloporins?

Answer 21

• pigment in coral tissue
• homologous to GFP - luciferins
• do not luminesce
• diffuse harmful light

Question 22

what does bleaching do to algae?

Answer 22

allow exchange of algae with diff FPs
- by bleaching and removing one type of zooxanthellae can coral take up another that works better at a diff temp
-> transplantation of coral colonies from shallow to deep and deep to shallow showed a change in algal community

Question 23

where does carbonate ions steal calcium from?

Answer 23

shells

Question 24

what are the conservation problems for reefs?

Answer 24

• low gamete density -> too few corals result in too few gametes - Allee effect, leads to success of brooders, low density means low reproduction
• disease -> pathogens weaken coral’s resistance to increased water temp
• shifting ecological balance -> predation, Diadema and Acanthaster
• eutrophication (increased nutrients) - upsets the balance, algae covers the coral meaning no photosynthesis and death