LEC 19 - CORAL REEFS II (ECOLOGICAL INTERACTIONS)

Question 1

what is the difference bw brooding and spawning?

Answer 1

brooding: catching a sperm and internal fertilizing

spawning: releasing the egg and sperm and hoping they find their way

Question 2

what conditions may alter spawning patterns? (4)

Answer 2

• season (spring/fall)
• time of night (state of the tide)
• weather (calmness of the water column)
• chemical release by other corals

Question 3

what mechanics do corals have to prevent hybridization?

Answer 3

controlling spawning pattern

Question 4

how do coral productivity rates compare to elsewhere? what causes this? (5)

Answer 4

coral prod rates are super high

caused by:
- algal symbionts
- providing a place for animals to live
- algae (but not the symbiont)
- animals chillin (but not living there, just hunting and shit)
- upwelling (not much but its there)

Question 5

what causes the diversity of fish seen around reefs? (4 ideas, one main cause)

Answer 5

• competition results in specialization
• lottery: fish aren’t specialized, corals just have hella niches to take up
• predation disturbance: fish mainly respond to disturbance, not predators/competition
• recruitment limitation hypoth: adult pops reflect larval recruitment for a given year

and the winner is… contestant number 3!

Question 6

who are the most important fish in keeping corals healthy?

Answer 6

the grazers - when algae that isn’t the symbiont gets too abundant, it creates competition w the zoox in coral

Question 7

is coral bleaching? why does it occur? (3)

Answer 7

coral bleaching is a response to environ conditions in which the coral ejects its algal symbionts

not all ejection spells death - in fact, it is proposed that algal symbionts may be ejected in favour of those that can handle the conditions (ex. UV light)

some conditions incl changing temps, bact infection, and UV light

Question 8

do corals prefer one breed of algal symbiont or a wide range?

Answer 8

a wide range, to respond to as many wavelengths of light as possible

Question 9

why are crown of thorns starfish so bad?

Answer 9

feed on corals + have very few predators so they can fuck up an entire ecosystem because hungies XD

Question 10

what are pocilloporins?

Answer 10

genetically homologous to luciferins, though they dont cause glowing. they do diffuse harmful light, however (fluorescent pigments do that)

Question 11

what can we do to help combat coral bleaching?

Answer 11

we can manually transplant algal symbionts to diff corals with some degree of success (baker 2001 experiment)

Question 12

what intensifies the effects of coral bleaching?

Answer 12

increased CO2 levels caused by global warming decreases the ability for coral to recover

Question 13

how does incr atmospheric CO2 affect corals? how do sea urchins illustrate this?

Answer 13

atmospheric CO2 gets into the water via the water cycle

if u recall, carbonic acid naturally resolves itself into H20 and CO2. however, when there is an excess of CO2, it drives the equation backwards.

when there’s a lot of carbonic acid, it breaks down into bicarbonate ions and furthering into carbonate ions (and also hydrogen ions, indicating acidity).

these carbonate ions like to bind w calcium, and normally we coral doing this for building their calcium carbonate skeleton. however, now this is just happening in the water, forcing corals to compete w nature itself.

sea urchins illustrate this in growing shorter limbs, which decr their survival chances (less access to food etc)

Question 14

what are some other conservation problems for reefs?

Answer 14

• dying out subjects them to the allee effect (not enough gametes further brings down the pop)
• disease (weakened corals make pathogens nut a little)
• eutrophication of oceans is not helping their growth