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Global Change Biology > Oceans > Flashcards

Oceans Flashcards

1
Q

Where are coral reefs concentrated

A

The central indo-Pacific

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2
Q

What is the biology of corals

A

Colonial animal

Polyps are Symbiotic with algae (zooxqnthellae)

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3
Q

What give corals there colour

A

Algae and without it they would be clear. Also gives energy

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4
Q

What percentage of all marine species do coral reefs host

A

25% recent estimates suggest 33%

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5
Q

Why are coral reefs most diverse ecosystem on earth for vertebrates (hyperdiverse)

A

Complex reef structure with refuge holes and caves and complexity for lots of other animals to life within.
For fish, coral grows with different size holes to live in and provides niche for water flows and light intensity.

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6
Q

What percentage of all ocean area is corals

A

0.1%

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7
Q

How much do coral reefs contribute exostatems worth

A

$9.9 trillion eac year

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8
Q

What are the theee main values of coral reefs

A

Fisheries particularly subsidence and local ones.
Shoreline protection as the coral habitat dissipates energy.
Tourism.
Also property prices bc of health benefits of being near environment

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9
Q

What 3 interactions are there in coral reefs

A

Predation
Competition
Mutualism

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10
Q

What percentage coral cover is healthy coral

A

40%. Benthos should be made of algae and soft coral

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11
Q

What 6 threats to coral reefs cause them to decline globally

A 
Nutrient enrichment 
Over fishing
Aquarium trade
Crowns of thorns starfish outbreak
Dredging for coal ports
Increasing cyuclone intensity
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12
Q

How does nutrient enrichment cause decline in corals

A

Excess nitrogen favours algae growth not coral so algae competing with coral for space become more successful when loads of nutrients are added

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13
Q

How does aquarium trade cause decline of coral

A

Some species are harvested in high numbers

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14
Q

How are COTs outbreak causing decline of coral

A

They feed on live coral and periodically you can get huge outbreaks in their numbers. Probably bc of nutrient enrichment their larvae can survive

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15
Q

What percentage of coral cover can COT larvae strip

A

9%

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16
Q

What is are global climate right now

A

405ppm

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17
Q

What is coral bleaching

A

A stress response where corals lose their symbiotic algae

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18
Q

How do corals gain energy

A

Photosynthesis of their symbiotic algae

Catching plankton in the water column with their tentacles 🦑

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19
Q

What percentage of corals energy comes from algae

A

90%

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20
Q

How do corals and their symbiotic algae engage in mutualism

A

The algae photosynthesis in coral and give it energy.
Coral provides somewhere for algae to live.
Adaption tO nutrient poor conditions.

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21
Q

Why did the symbiotic relationship between coral and algae think to evolve

A

Bc corals living in nutrient poor oligotrophic enguments ao croaks are building incredibly productive ecosystems besides being nutrient poor . The algae brings energy and nutrients through photosynthesis.

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22
Q

What happens during bleaching

A

Symbionts reduced by 60-90% in days
Loss of tissue biomass
Coral skeleton visible through transparent tissue
Density of single celled algae living in tissue reduces bc coral can’t feed.

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23
Q

Why are the calcium carbonate skeletons of coral visbible in bleaching

A

Bc the colour is gone due to algae dispersal

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24
Q

What do corals secrete

A

Photoprotective fluorescent proteins that can reflect and dissipate UV light

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25
Q

What is the bleaching process

A

Damage to the photosynthetic apparatus.
Generates large amounts of reactive oxygen species.
Overwhelm oxygen-handling pathways.

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26
Q

What damage to the photosynthetic apparatus occurs in bleaching

A

The D1 protein in PSII
The Calvin cycle
The thylakoids membrane

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27
Q

What are examples of reactive oxygen species

A

Singlet oxygen 1O2

Superoxide O2-

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28
Q

What are the oxygen handling pathways

A

Major cell damage

Host cells eject zooxanthellae

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29
Q

Why may symbiotic algae be ejected by the coral

A

Bc they are starting to poison it themselves

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30
Q

What 3 ways does the algae leave the coral

A

It dies
It gets ejected
It leaves

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31
Q

After the algae is ejected how long does the coral have

A

2-3 weeks

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32
Q

What does DHW stand for

A

Degree heating weeks

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33
Q

What is the name of the coral reef watch

A

NOAA coral reef watch

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34
Q

What does the DHW accumulate

A

The instantaneous bleaching thermal stress (measured by coral bleaching hot spots) during the most recent 12 week period.

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35
Q

What is DHW directly related to

A

The timing and intensity of coral bleaching

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36
Q

What DHW gets reached to signify significant coral bleaching

A

4*C weeks

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37
Q

What happens when DHW reaches 8*C weeks

A

Widespread bleaching is likely and sinricant mortality can be expected

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38
Q

How to work out DHW

A

Weeks measured times temperature above normal sea temperature

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39
Q

What are mass bleaching events strongly linked to

A

Sustained elevated ocean temperatures

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40
Q

When can corals recover from bleaching

A

If the stress is not too prolonged

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41
Q

How can coral recover from bleaching

A

If stress is removed and they go back to normal range somedirals surface as symbiotic algae increases in population size again, either being reabsorbed or growing in the coral. New larvae settle and establishes new colonies.

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42
Q

How long does it take for a reef to start recovering

A

Decades

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43
Q

What was the worst recorded bleaching event

A

The global coral bleaching event (GCBe) 2014-2017

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44
Q

What caused the GCBE

A

El Niño event heating up the eastern Pacific and causing surface temp to rise. Natural but so much stress of coral reefs killing them.

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45
Q

Where did the GCBE occur

A

Globally in Maldives, Japan, Hawaii, kook islands, great barrier reef

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46
Q

During the GCBE how much of Japan’s coral died

A

75%

47
Q

During the GCBE how much coral died in the seychelles

A

70%

48
Q

How much of the reefs in the Great Barrier Reef were effected

A

93%

49
Q

What did an aerial bleaching survey show of the GCBE

A

A large spatial variation in bleaching impact - northern sector(no settlements) was worth bleached at 99%, central has 90% and southern sector at 75%

50
Q

Why was the southern sector less effected in the GCBE

A

Because the bottom end was tail end of the cyclone that past figi so a lot of cool water past

51
Q

What happens to dead coral

A

The Skeleton structure gets left behind and gets covered in slime and algae

52
Q

What did they find when the GBR was resurveyed after 6months

A

In the north 2/3 of coral has died
In central 6% died
In south 1%
Mass mortality of coral colonies but regional differences as it ranges from 1% to 67%

53
Q

What happened in 2017

A

The Great Barrier Reef got hit with another event and central got very damaged.

54
Q

What are bleaching events increasing in

A

Frequency and severity

55
Q

By 2016 what is the frequency of bleaching events

A

Every 6 years so by a lot of time to bounce back

56
Q

What happens to the habitat if coral dies

A

The structure ends up collapsing and ends with rubble on ground and destroyed habitats

57
Q

What is collapse of coral reef habitat known as

A

Flattening

58
Q

What does the flattening of Caribbean coral reefs show

A

That structural complexity has declined through time and reefs have become more flat providing less structure for animals

59
Q

What percentage of coral did the sychellea lose in 1980

A

98%

60
Q

What happened to the fish species in sites that lost lots of its coral

A

50% decline of species diversity

61
Q

Example of specialisation (outcompekting other fish)

A

Corallivores

62
Q

What are 3 different types of butterfly fish

A

Facultative ns
Obligate generalist
Obligate specialise

63
Q

What do facultative ns feed on

A

Small worms so not affected much by coral

64
Q

What do obligate generalists feed on

A

Coral but lots of different type so decline but not completely gone

65
Q

What do obligate specialist feed on

A

Only 2, 3 types of coral so huge decline

66
Q

What is the example of monitoring in the Seychelles

A

Surveyed 21 reefs.
12 bounced back.
2014 - coral cover has recovered but where reefs hadn’t the macroalgae took over so it is 80% of surface is covered by sea weed.
New corals can’t settle and establish and sea weed kills them with chemicals.
Mechanism to maintain dominant space.
Regime shift.

67
Q

What happenes when some corals respond differently to bleaching

A

End up with winner and losers scenario which filters out some species of coral whereas some survive and maintain its space. A turn over in types of coral and their ability to survive with their structure being different.

68
Q

When does ocean acidification happen

A

When excess co2 is absorbed from the atmosphere

69
Q

What is the ph of sea water

A

Slightly alkaline 8.16

70
Q

What is the chemical reaction of ocean acidification

A

Atmospheric co2 tO dissolved co2 and sea water. Goes to carbonic acid which goes to bicarbonate ions and hydrogen ions. Bicarbonate ions goes to carbonate ions and hydrogen ions

71
Q

What are bicarbonate ions needed to form

A

Shells and skeletons

72
Q

What happens as carbon dioxide in the ocean increases

A

Ocean pH decreases (acid) and calcium carbonate supply decreases

73
Q

What do hydrogen ions in the ocean do

A

Increase the acidity

74
Q

What do many marine species create through calcification

A

Hard structures

75
Q

Examples of calcification

A 
Hard corals
Foraminifera
Fish otoliths
Limpets and barnacles
Macroalgae 
Coccolithophores
76
Q

Why does OA mean there is less essential material available for organisms to make structures

A

Dissolved calcium ions in water forms with carbonate ions to calcium carbonate but less carbonate ions means less calcium carbonate and structures built

77
Q

What is the calcifying plankton experiment

A

Raining plankton in 3 different concentrations of co2.
140ppm, 345 ppm, 915ppm.
Responding strongly to change in co2 and can’t build structures correctly.

78
Q

What do individual polyps build

A

Cups called corallites

79
Q

Why are coral reefs a highly threatened ecosystem

A

Because the entire structure of the reef is based on calcification

80
Q

What is the growth decline of massive porites

A

14%

81
Q

What are massive porites

A

Huge boulder that grow incredibly slowly. 5,6,700 years old

82
Q

What is the experiment for coral skeletons not forming properly under acidic conditions

A

60 day experiment.
Corallites were shorter.
Corallite infilling was reduced when also exposed to unusually high or low temperatures.

83
Q

What increases net calcification

A

Alkaline enriched water

84
Q

What can offer clues about OA

A

Natural co2 seeps

85
Q

What do volcanic weeps do

A

Naturally release co2 into the water column

86
Q

What is pH at volcanic seeps

A

Similar to expected change by the end of century, from 8.1 to 7.8

87
Q

What is the different when comparing communities around seeps with nearby non-seep communities

A

Seeps had lower coral diversity, recruitment and abundance; altered species interactions but there was little difference in coral cover

88
Q

Where are examples of natural co2 seeps

A

In papa New Guinea

89
Q

What can coral invest to alter the pH internally so they can continue to calcify effectively

A

Some energy

90
Q

How can OA alter fish behaviour

A

They use the smell to find coral reefs and avoid predators usually but after acidification they chose to swim up the floom with predators.

They also use hearing to avoid predators when juvenile. Typically they avoid the sound of a day time diurnal reef. As you acidify the water using 3 levels of gradual acidification means their avoidance breaks down and 60-70% of the time they are attracted to the sound.

91
Q

What as Munday looked at

A

Generation - finds you get a trans generation response to detect their parents again. Coral reef fish homing ability

92
Q

What happened to the fish in Mundays experiment

A

Under acidic conditions they begin to switch and go up towards predators - 100% after 10 days. Under lower levels they avoid predators at 700ppm their ability to chose between the two breaks down but at 850ppm they chose to swim towards it.

93
Q

Why is the fact that clown fish swim towards parents during acidification a bad thing

A

They want to settle ina. Reef without parents to find a mate

94
Q

What have OA experiments been critiqued

A

Will have an effect but magnitude of effect is disputed
Inability to replicate in some cases
Publication bias
Variability in natural environment - extreme scenarios often used

95
Q

What are variations in natural environment due to

A

Tides and flushing and currents

96
Q

What are coral reefs expected to do in response to climate change

A

Change distribution, composition and state

97
Q

What did Couce predict

A

Projected change in suitability for coral reefs from 1990 to 2070 based on temperature and OA. They are bound in temp at -18*C, ability to fix calcium carbonate in sea water is higher in tropics, examples in not too distance past of shifts outside these distributions.

98
Q

In japan at what rate are corals able to grow

A

14km per year

99
Q

Example of unexpected shift of coral reef distribution

A

Western Australia. Usually grow further south.

East and west coast. 2011 huge heat wave killed 200km of kelp on coast and a lot of fish. Coral dominates

100
Q

Why do corals shift their distributions towards the poles

A

To track optimum temperature

101
Q

Why are is the increase in Japan ranging from 1 - 2.5 degrees in water

A

Bc warm currents are strengthening and pumping warm water up there making it warm rapidly leading to rapid extension of where reefs are

102
Q

What is happening to the old reef tract in Florida

A

It is shallow enough and now has right conditions for corals to dominate

103
Q

What could impact the potential for range shifts

A

Dispersal on ocean currents

Light in higher altitudes

104
Q

What does the direction and speed of boutant coral larvae depend on

A

Surface ocean currents, could curtail shifts or allow corals to shift long distances

105
Q

What did Glynn invent

A

The Deep Reef Refugia Hypothesis

106
Q

What is the deep reef refugia hypothesis

A

30-40m Deeper reefs are buffered form negative environmental impacts.
These reefs can be a source of larvae to replaneish shallower reefs after disturbance.

107
Q

What has happened since mapping included deeper reefs

A

Known area of reef in the GBR has doubled from 20,000 to 40,000

108
Q

Example of coral reef in Sydney

A

Acropora

109
Q

Example of coral reef communities changing in composition

A

Acropora are decreasing and porites are increasing

110
Q

What has been documented over 15 years in japan

A

Simple structures are doing better but there’s been a collapse in other ones. Increased relative dominance of simple structures which has impact on diversity and fisheries

111
Q

How can doing something about local pressures help coral reefs

A

They interact with local climate change and the reef could bounce back

112
Q

What are the 5 predictors in the Seychelles about whether a reef would recover

A

In depth found below 7m more likely to recover due to light penetration and algal growth.
Rigidity found the structure of coral was important for keeping a lot of fish and other things that drive processes for recovery.
New corals.
Nutrient regime as more nutrients is likely to shift to macroalgae so prevents coral come back.
Juvenile coral density.
Biomass of herbivore.

113
Q

How can you a manage nutrients

A

Through catchments and fishery management

114
Q

How are corals projected to shift their distributions

A

Polewards and deeper

Global Change Biology (6 decks)

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