Oceans Flashcards
Where are coral reefs concentrated
The central indo-Pacific
What is the biology of corals
Colonial animal
Polyps are Symbiotic with algae (zooxqnthellae)
What give corals there colour
Algae and without it they would be clear. Also gives energy
What percentage of all marine species do coral reefs host
25% recent estimates suggest 33%
Why are coral reefs most diverse ecosystem on earth for vertebrates (hyperdiverse)
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.
What percentage of all ocean area is corals
0.1%
How much do coral reefs contribute exostatems worth
$9.9 trillion eac year
What are the theee main values of coral reefs
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
What 3 interactions are there in coral reefs
Predation
Competition
Mutualism
What percentage coral cover is healthy coral
40%. Benthos should be made of algae and soft coral
What 6 threats to coral reefs cause them to decline globally
Nutrient enrichment Over fishing Aquarium trade Crowns of thorns starfish outbreak Dredging for coal ports Increasing cyuclone intensity
How does nutrient enrichment cause decline in corals
Excess nitrogen favours algae growth not coral so algae competing with coral for space become more successful when loads of nutrients are added
How does aquarium trade cause decline of coral
Some species are harvested in high numbers
How are COTs outbreak causing decline of coral
They feed on live coral and periodically you can get huge outbreaks in their numbers. Probably bc of nutrient enrichment their larvae can survive
What percentage of coral cover can COT larvae strip
9%
What is are global climate right now
405ppm
What is coral bleaching
A stress response where corals lose their symbiotic algae
How do corals gain energy
Photosynthesis of their symbiotic algae
Catching plankton in the water column with their tentacles 🦑
What percentage of corals energy comes from algae
90%
How do corals and their symbiotic algae engage in mutualism
The algae photosynthesis in coral and give it energy.
Coral provides somewhere for algae to live.
Adaption tO nutrient poor conditions.
Why did the symbiotic relationship between coral and algae think to evolve
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.
What happens during bleaching
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.
Why are the calcium carbonate skeletons of coral visbible in bleaching
Bc the colour is gone due to algae dispersal
What do corals secrete
Photoprotective fluorescent proteins that can reflect and dissipate UV light
What is the bleaching process
Damage to the photosynthetic apparatus.
Generates large amounts of reactive oxygen species.
Overwhelm oxygen-handling pathways.
What damage to the photosynthetic apparatus occurs in bleaching
The D1 protein in PSII
The Calvin cycle
The thylakoids membrane
What are examples of reactive oxygen species
Singlet oxygen 1O2
Superoxide O2-
What are the oxygen handling pathways
Major cell damage
Host cells eject zooxanthellae
Why may symbiotic algae be ejected by the coral
Bc they are starting to poison it themselves
What 3 ways does the algae leave the coral
It dies
It gets ejected
It leaves
After the algae is ejected how long does the coral have
2-3 weeks
What does DHW stand for
Degree heating weeks
What is the name of the coral reef watch
NOAA coral reef watch
What does the DHW accumulate
The instantaneous bleaching thermal stress (measured by coral bleaching hot spots) during the most recent 12 week period.
What is DHW directly related to
The timing and intensity of coral bleaching
What DHW gets reached to signify significant coral bleaching
4*C weeks
What happens when DHW reaches 8*C weeks
Widespread bleaching is likely and sinricant mortality can be expected
How to work out DHW
Weeks measured times temperature above normal sea temperature
What are mass bleaching events strongly linked to
Sustained elevated ocean temperatures
When can corals recover from bleaching
If the stress is not too prolonged
How can coral recover from bleaching
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.
How long does it take for a reef to start recovering
Decades
What was the worst recorded bleaching event
The global coral bleaching event (GCBe) 2014-2017
What caused the GCBE
El Niño event heating up the eastern Pacific and causing surface temp to rise. Natural but so much stress of coral reefs killing them.
Where did the GCBE occur
Globally in Maldives, Japan, Hawaii, kook islands, great barrier reef
During the GCBE how much of Japan’s coral died
75%
During the GCBE how much coral died in the seychelles
70%
How much of the reefs in the Great Barrier Reef were effected
93%
What did an aerial bleaching survey show of the GCBE
A large spatial variation in bleaching impact - northern sector(no settlements) was worth bleached at 99%, central has 90% and southern sector at 75%
Why was the southern sector less effected in the GCBE
Because the bottom end was tail end of the cyclone that past figi so a lot of cool water past
What happens to dead coral
The Skeleton structure gets left behind and gets covered in slime and algae
What did they find when the GBR was resurveyed after 6months
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%
What happened in 2017
The Great Barrier Reef got hit with another event and central got very damaged.
What are bleaching events increasing in
Frequency and severity
By 2016 what is the frequency of bleaching events
Every 6 years so by a lot of time to bounce back
What happens to the habitat if coral dies
The structure ends up collapsing and ends with rubble on ground and destroyed habitats
What is collapse of coral reef habitat known as
Flattening
What does the flattening of Caribbean coral reefs show
That structural complexity has declined through time and reefs have become more flat providing less structure for animals
What percentage of coral did the sychellea lose in 1980
98%
What happened to the fish species in sites that lost lots of its coral
50% decline of species diversity
Example of specialisation (outcompekting other fish)
Corallivores
What are 3 different types of butterfly fish
Facultative ns
Obligate generalist
Obligate specialise
What do facultative ns feed on
Small worms so not affected much by coral
What do obligate generalists feed on
Coral but lots of different type so decline but not completely gone
What do obligate specialist feed on
Only 2, 3 types of coral so huge decline
What is the example of monitoring in the Seychelles
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.
What happenes when some corals respond differently to bleaching
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.
When does ocean acidification happen
When excess co2 is absorbed from the atmosphere
What is the ph of sea water
Slightly alkaline 8.16
What is the chemical reaction of ocean acidification
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
What are bicarbonate ions needed to form
Shells and skeletons
What happens as carbon dioxide in the ocean increases
Ocean pH decreases (acid) and calcium carbonate supply decreases
What do hydrogen ions in the ocean do
Increase the acidity
What do many marine species create through calcification
Hard structures
Examples of calcification
Hard corals Foraminifera Fish otoliths Limpets and barnacles Macroalgae Coccolithophores
Why does OA mean there is less essential material available for organisms to make structures
Dissolved calcium ions in water forms with carbonate ions to calcium carbonate but less carbonate ions means less calcium carbonate and structures built
What is the calcifying plankton experiment
Raining plankton in 3 different concentrations of co2.
140ppm, 345 ppm, 915ppm.
Responding strongly to change in co2 and can’t build structures correctly.
What do individual polyps build
Cups called corallites
Why are coral reefs a highly threatened ecosystem
Because the entire structure of the reef is based on calcification
What is the growth decline of massive porites
14%
What are massive porites
Huge boulder that grow incredibly slowly. 5,6,700 years old
What is the experiment for coral skeletons not forming properly under acidic conditions
60 day experiment.
Corallites were shorter.
Corallite infilling was reduced when also exposed to unusually high or low temperatures.
What increases net calcification
Alkaline enriched water
What can offer clues about OA
Natural co2 seeps
What do volcanic weeps do
Naturally release co2 into the water column
What is pH at volcanic seeps
Similar to expected change by the end of century, from 8.1 to 7.8
What is the different when comparing communities around seeps with nearby non-seep communities
Seeps had lower coral diversity, recruitment and abundance; altered species interactions but there was little difference in coral cover
Where are examples of natural co2 seeps
In papa New Guinea
What can coral invest to alter the pH internally so they can continue to calcify effectively
Some energy
How can OA alter fish behaviour
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.
What as Munday looked at
Generation - finds you get a trans generation response to detect their parents again. Coral reef fish homing ability
What happened to the fish in Mundays experiment
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.
Why is the fact that clown fish swim towards parents during acidification a bad thing
They want to settle ina. Reef without parents to find a mate
What have OA experiments been critiqued
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
What are variations in natural environment due to
Tides and flushing and currents
What are coral reefs expected to do in response to climate change
Change distribution, composition and state
What did Couce predict
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.
In japan at what rate are corals able to grow
14km per year
Example of unexpected shift of coral reef distribution
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
Why do corals shift their distributions towards the poles
To track optimum temperature
Why are is the increase in Japan ranging from 1 - 2.5 degrees in water
Bc warm currents are strengthening and pumping warm water up there making it warm rapidly leading to rapid extension of where reefs are
What is happening to the old reef tract in Florida
It is shallow enough and now has right conditions for corals to dominate
What could impact the potential for range shifts
Dispersal on ocean currents
Light in higher altitudes
What does the direction and speed of boutant coral larvae depend on
Surface ocean currents, could curtail shifts or allow corals to shift long distances
What did Glynn invent
The Deep Reef Refugia Hypothesis
What is the deep reef refugia hypothesis
30-40m Deeper reefs are buffered form negative environmental impacts.
These reefs can be a source of larvae to replaneish shallower reefs after disturbance.
What has happened since mapping included deeper reefs
Known area of reef in the GBR has doubled from 20,000 to 40,000
Example of coral reef in Sydney
Acropora
Example of coral reef communities changing in composition
Acropora are decreasing and porites are increasing
What has been documented over 15 years in japan
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
How can doing something about local pressures help coral reefs
They interact with local climate change and the reef could bounce back
What are the 5 predictors in the Seychelles about whether a reef would recover
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.
How can you a manage nutrients
Through catchments and fishery management
How are corals projected to shift their distributions
Polewards and deeper
