Ocean Acidification Flashcards
(107 cards)
1
Q
what is ocean acidification?
A
the ongoing decrease in teh pH value of the earth’s ocean. it is the changing of the amount of carbonate minerals that are available to marine organisms
2
Q
what is the normal pH of the ocean?
A
8.1
3
Q
what causes ocean acidification?
A
anthropogenic interference. industrial revolution, has direct and indirect effects.
humans directly and indirectly influences the oceans chemistsry
4
Q
what are the direct effects of anthropogenic causes of ocean acidification?
A
Fluxes of materials in the ocean
5
Q
what are the indirect effects of anthropogenic causes of ocean acidification?
A
climate change and altered ocean acidification
6
Q
what are the 4 anthropogenic sources of atmospheric CO2?
A
burning of fossil fuels
deforestation
changes in land use
energy and cement production
7
Q
what are the 3 sinks of anthropogenic CO2?
A
atmosphere
ocean
land
8
Q
what percentage of CO2 emissions does the ocean uptake?
A
20-35% , 1/3rd
9
Q
what is the historical changes in atmospheric CO2 measurement?
A
the past 800,000 years, it has been around 172-290 parts per million by volume.
10
Q
what is the recent atmospheric CO2 measurement?
A
since the industrial revolution, it is now 280-410 ppmv
11
Q
what does ppmv stand for?
A
this is what atmospheric CO2 is calculated in, it means parts per million by volume
12
Q
what is the issue with CO2 in the ocean?
A
it has a knock on effect to marine ecosystems and animals
13
Q
how does the CO2 enter ocean water?
A
the CO2 diffuses passively into ocean surface water.
14
Q
how does the CO2 in the ocean cause the pH to be lowered?
A
there, it combines with the sea water and forms acrbonic acid, which is a weak acid. it dissociates to create biocarbonate and H ions. the H ions cause the sea water pH to fall due to it being acidic.
the H ions react with other H ions, which produces bicarbonate. this is a natural buffering capacity.
the dissociation of carbonic acid causes a lot of the H ions, which lowers the pH. due to the buffering capacity, the carbon ion concentration is LOWERED substantially.
15
Q
what is natural bufering capacity?
A
this is the natural buffering that oceans do to reduce the impact of an increase in H ions. this natural buffering capacity causes the ocean to be stable at 8.1 pH
16
Q
what happens to H ions if there is more CO2 in the ocean?
A
the more CO2 in the ocean, the more H ions combine with the carbonate, and lowers the pH
17
Q
what is the chemical equation for ocean acidification?
A
CO2 > CO2 + H20 > H2CO3 > HCO3- + H+ > More H+ , Buffering > HCO3-
CaCO3 > CA2+ + CO3^2-
(this goes into H+ addition)
18
Q
why is the decrease of carbonate and increase of H+ an issue for marine life?
A
many marine organisms use this for shells and skeletal structures
19
Q
what is carbonate saturation?
A
atmospheric CO2 can only be absorbed if enough CaCO3 dissolves in the water column or sediments
20
Q
what is the chemical equation for carbonate saturation?
A
CaCO3 < > CO3^2- + Ca^2+
21
Q
what is the chemical equation for CaCO3 formation and dissolution rates?
A
weird symbol O = [Ca^2+] [CO3^2-]/K’sp
22
Q
what level of carbonate saturate causes calcification?
A
must equal more than 1, this is supersaturation and is a biotic process which forms shells and skeletons
23
Q
what level of carbonate saturate causes undersaturation?
A
must be less than 1, which is undersaturation. this is dependent on abiotic environment. and dissolution of shell and skeleton
24
Q
what is aragonite?
A
a form of CaCO3, which is soluble.
25
where is aragonite found?
in many tropical corals, cold-water corals, pteropods and mollusks
26
what is calcite?
a form of CaCO3, soluble
27
where is calcite found?
coccolithophores, foraminifera, echinoderms and crustaceans
28
which is more soluble, aragonite or calcite?
aragonite
29
which form of CaCO3 does coral growth benefit from being high in?
aragonite, benefits from high aragonite saturation states above 3
30
what are abiotic controls of carbonate saturation state?
CO2 solubility depends on:
temperatrue
salinity
pressure
31
is CO2 less or more soluble in warmer temperatures?
LESS soluble
32
where does a higher CaCo3 saturation state occur?
shallow, warm tropical waters
33
where does a lower CaCo3 saturation state cause?
cold, high latitude regions and at depth
34
where is the effect of enhanced CO2 in the oceans?
colder, deeper regions
35
what level of CaCO3 does warm waters have?
higher carbon concentration, and are more saturated with carbon minerals
36
in polar regions, what do organisms do to ensure survival?
organisms will have to use more energy to maintain their shell and prevent the dissolution of their shells
37
what does the ocean imbalance mean?
that the ocean is reducing in pH, causing it to be acidic
38
what does the solubility of CO2 and CaCO3 depend on?
temperature, salinity and pressure
39
where is CO2 more soluble?
in cold waters and higher pressures. more is taken up, and the effect of enhanced CO2 is going to be stronger.
40
what is the relationship between CO2 concentration in the atmosphere and the surface ocean?
linked increase, steadily increasing over tha past 30 years.
41
what is the relationship between seawater pH and carbonate concentration
concomitant decline
42
when was the important Royal Society Report published which introduced carbonate chemistry research?
2005
43
what did the famous Royal Society Report focus on?
carbonate chemistry and the little knowledge about ecological impacts
44
what happened after the famous Royal Society Report got published in 2005?
the research for carbonate and impacts increased significantly, with now over 7,360 publications
45
why was the Royal Society Report interesting?
it focused largely on carbonate chemistry of the sea, and how carbon is changing due to warming and CO2. not much was known in 2005 about this, in terms of the potential ecological impacts of OA on organisms and ecosystems.
46
what is the biological response on ocean acidification?
a LARGE negative effect.
47
which biological responses are actually benefitted or have no response to enhance CO2 in the water content?
photosynthesis and nitrogen fixation
48
what are the current trends based on multi-species experiments on CO2 increase?
increase in 1 degree Producer biomass
Decrease in taxonomic diversity
some species able to survive or even thrive in high CO2 conditions.
49
which processes INCREASE during CO2 increase?
```
Bioerosion
macroalgal overgrowth
primary productivity
grazing by herbivores
dissolution
harmful algal blooms
secondary productivity
```
50
which 4 processes DECREASE during CO2 increase?
overall calcification
calcifer recruitment
structural complexity
taxonomic diversity
51
which processes INCREASE AND DECREASE during CO2 increase?
macroalgal competition in seagrass meadows
52
which processes CHANGE during CO2 increase?
community structure in pelagic food webs
| community structure in coral reefs
53
which species can thrive in high CO2 conditions
species which do not reply on photosynthesis
54
what does the life-stage dependent response to OA depend on?
the life stage of the organism
55
what are the significant differences in life-stage dependent responses to OA?
significant differences in their survival and metabolic rate
56
what is metabolic depression?
reduces the chance of survival
| an adaptive biological process for energy preservation, is responsible for torpor, hibernation and estivation
57
under OA conditions, what happens to molluscs?
decreased metabolic rate, and a decrease in shell growth.
| this is more prominent over a longer period
58
how does low pH affect molluscs?
oxygen consumption and their growth is significantly reduced
59
why are molluscs affected by OA?
due to the dissolution of the CaCO3 shells occurring
60
what is metabolic up-regulation?
to maintain/increase calcification and compensate for dissolution due to increased seawater acidity
61
how do animals regulate to live in increased sea water acidity?
they are able to metabolically regulate their physiologic mechanisms to increase calcification, and are able to compensate dissolution
62
what is the cost of animals being able to regulate themselves in increased acidic conditions?
there was extensive muscle loss.
63
how did the experiment which was viewing how organisms were affected by OA, work out that muscles were reduced?
Took the arms and cut the arms off and looked at longitudinal sections of the arms to look at the calcium carbonate skeleton and the muscle structures.
You can see with increasing pH, the muscle is significantly reduced.
This came at the cost of muscle wastage.
64
what happens to organisms over long term in OA conditions?
significant implications for the species' survival.
The animals after 18 months of exposure at low pH (7.7), that they are a lot more delicate. Outside structures looked fine, but internally they were damaged significantly.
65
can ocean acidification effect sound production?
it was found that sound recordings in CO2 effected areas, there as a decline in intensity and frequency of sound levels.
The number of snaps and the pressure level of the sound was significantly Decreased under extreme CO2 conditions.
therefore, yes
66
how does OA effect feeding behaviour (foraging behaviour)
OA influences the calcification rates of many organisms.
If shell structures are weakened, more likely to be preyed upon.
Reducing in calcification in the oyster (prey). Big reduction for the predator. Also showed a decrease in predator rate.
There was a strong negative effect on crab foraging behaviour- predation attempts. Reduction in all of these behavioural responses.
Under increased OA, hypotehsis is the prey will be predated on more due to weakened shell.
This was untrue, as predator was also storngly affected.
It can be both or just the prey. It has the potential for complex changes in interactions in the food web interactions.
67
how does OA effect species behaviour in clown fish?
The discriminatory ability of the clown fish larvae was lost, and the larvae because attracted to predators that they would normally avoid. Couldn't distinguish between predator and non-predator cues.
Significant long term effects on the survival of the species.
68
how does OA affect species behaviour in Hermit crabs?
Crabs couldn't find shells. OA affects the crab's ability to find a really good and suitable shell replacement.
Hermit crabs take a lot longer to find an optimal shell. And their feeding and detecting of food sources take a lot longer than under ambient seawater conditions.
69
how does OA affect species behaviour in fish in terms of home sites
Changes in the behaviour of predator avoidance and not being able to find the right settlement sites. This can have an impact of the linkages between marine food webs.
70
what are tractable experiments?
an experiment which is easily controlled and regulated
71
why are tractable experiments used for ecological relevance studies?
organisms experience dynamic environmental conditions
high variability in response to short term experiments
more long-term experiments are needed
OA is NOT an isolated phenomenon, but is happening at the same time as multiple other stressors
focus is still on limited set of taxa
72
what other stressors are occurring in the ocean at the same time as OA?
changes in temperature, deoxygenation, eutrophication, habitat destruction and various others
73
why are manipulative experiments not necessarily the best in the case of OA measuring?
natural observations are needed
74
what may be impacted by altered behaviour in marine consumers?
may weaken predator-prey links in marine food webs, causing cascading effects on community structure and function.
75
what was Tatoosh Island a case study for?
to show how naturally various environmental conditions are. they took measurements of pH, temperature and other variables over a long period of time to show fluctuations.
76
what did the Tatoosh case study show?
that between 2000-2008, there were very strong fluctuations daily, and the pH varies quite substantially between different types of the year.
in the warmer months, pH is higher. colder months, the pH reduces.
77
what needs to be taken into account when considering the effects of OA?
it depends in the environment. there are very strong differences between ecosystems.
Organisms are already experiencing pH changes that arent predicted to happen until 2100 on a daily basis.
On OA< we need to take in account the importance of enviornmental history and physiological history that is already shown, as this may or may not show the fluctuation of pH.
In an estuary, there is STRONG fluctuation.
In the open ocean, it is MUCH MORE STABLE
This is due to the change in the balance of respiratory and consumption of corals and algae. This is what causes these localised changes in pH
78
what are the organism impacts on local pH?
modification of the biochemistry of their immediate environment, through their behaviours.
79
how does the organisms cause pH change burrow sections through fresh o2 levels?
the stability changes. the burrow sections where the worm brings in O2 rich water, expels the suboxic water out of its burrow. The surrounding sediment is WAY below predictions at a pH around 7. the organisms can really modify the chemistry of the enviornment through thier behaviour. In this case, they bring O2 rich water down into teh borrows, and expels the deoxygenated water out.
80
how do coral reefs modify pH naturally
They modify the water column through carbon production and calcification.
There are strong changes in pH, generally a high increase in pH during high light levels.
81
what happens daily in a Kelp Forest in terms of Natural variability?
daily changes of pH from photosynthesis and respiration. The changes this environment experiences are much larger than the changes from OA. In some regions, night time pH can reduce to pH7,4.
These fluctuations are SHORT TERM. There is a relief when it goes back to a higher pH conditions.
82
what happens in a cinema which is natural variation of atmospheric gases?
Over a 2 hour period in the cinema, CO2 levels have been shown to increase significantly over this 2 hour period.
This is more than worse case scenario for 2100 in CO2 concentrations.
83
how does human behaviour show what organisms do when their surroundings are uncomfortable for survival?
What do you feel? Start getting tired, room gets musty, just generally not a pleasant experience.
What do you do when you feel uncomfortable? You change your behaviour. You go outside, open the window- you go back to levels that are good for your wellbeing.
84
can calcification and metaobolic up-regulation be maintained over the long-term?
it was saw that over the short term, it is able to maintain due to metabolic regulation, but this came at the cost of muscle degradation.
In 18 month experiment, they looked at 3 levels of CO2, to reduce the pH to 7.9 and 7.7.
Also changed the seasonal cycle. Changed the tempearture, so the organisms would follow a more seasonal approach.
85
how does metabolic rate change with season and times?
In the summer, CO2 uptake was higher than it was in the winter
BUT, what was interesting what after 18 months, whilst the organism was still able to maintain their metabolic rate at 380ppm (ambient conditions), they showed signs of metabolic depression.
This is contrary to the short term effects, as they were NOT able to maintain their metablic rates over 18 months.
86
how are the skeleton structures affected by pH changes?
In the lowest pH, there is MUCH MORE PITTING than in the normal pH.
The organisms were not able to maintain their calcification rates.
87
what are the 4 effects of adult exposure influence in offspring response?
lower survival under high CO2 irrespective of adult conditioning
rate of development is reduced
growth reduced
selective breeding has positive carry-over effects on larvae
88
how was the larvae influences when exposued to high pH?
Interested in finding out whether there is a difference in teh offspring to how they respond
The larvae showed strong differences in survival between the ambient and elevated CO2. but not quite as much as those that were selectively bred.
BUT, when the larvae was spawned from adults that were CONDITIONED to CO2 high, you can see that the growth rate are generally higher irrespective of either wild or selectively bred.
89
waht does the study in larave and their breeding pattern show about organisms?
This study suggests the sensitivity of organisms might have the capacity to acclimatise over the next century to high CO2, and this might have something to do with their metabolic rate, and being able to increase it to support the survival processes.
90
how do natural CO2 vents influence the community structure of organisms?
Went and looked at the CO2 vent, pH gradient of 8.4 to 6.5 directly where the CO2 vent is.
What this showed was inside the vented area, the seagrass beds had much fewer calcified epiphytes compared to the sea grasses OUTSIDE the CO2 vents.
Also showed coral cover outside and inside vent. Calcifiying organisms such as the urchins (in the middle), all decreased in abundance moving from ambient to vented site.
The rate of loss REALLY DIFFERED
91
why is there a difference in dissolution between different mollusc species?
Could have something to do with the mineral structures of the skeleton? Aragonite vs calcite
Differences in shell densities
Genetics?
Evolved a protective layer.
92
why are some species able to resist OA
They have protective organic layers that protect the shells and layers.
Ability to maintain this protection at increased levels of CO2.
The inability to meet the increased metabolic demand on eh system to be able to cope in high CO2 systems, which meant they cannot rely on their protective layers.
The projected levels of OA are likely to increase the erosion of those organisms that do NOT have these biogenic carbonate protective structures
93
how does sea grasses thrive in OA?
they increase in abundance and densities
94
how does anemone thrive with OA and why?
Anemone increased significantly in the sites. This is because it has symbiotic algae within their tenticles and foot. Actually, the growth photosynthesis and respiration increased with CO2 concentrations, which increased growth of these. And this was in part responsible for these to increase thier metabolism and able to resist changes in pH
95
with a graph showing 8 days exposure, the pH decreases and decreases in growth, nad increases in CO2.
another graph shows 6 month exposure. the Growth increases.
what does this show?
Short exposure causes a decrease in growth and stress on the animals.
After long term exposure, the organisms adapt (acclimate) and are able to survive in the higher acidic pH conditions.
96
why does 8 days exposure effect organisms different to long term exposure?
8 day exposure could be just a shock response, and are shutting down and reducing their calcification.
In the 6 months, the animals are potentially getting used to the conditions, changing the functions.
97
what other factors are causing an increase of ocean temperature other than CO2 increase?
OA, warming, species reduction, invasions, hypoxia etc. These are all issues as well as higher CO2.
98
what are the 7 stressors that are affecting ecosystems in the ocean?
hypoxia, increasing fishing intensity, warming, habitat loss, species invasion, OA, pollution
99
A graph shows 70 day period and the relative growth percentage of starfish. the lower temperatures increase in relative growth LESS than a higher temperature.
Another graph shows that with 4 different temperatures and ppm, the feeding rate increases with a higher temperature and a higher ppm.
another graph shows moderately same levels of calcified mass in all different temp and ppm
what does this show?
7 week experiment looking at the starfish. Found that the growth and feeding rates under future warming, were much higher than under normal conditions. This is expected. Increase in metabolic rate.
They also found that as soon as you introduce an enhanced CO2 level into the mix, the starfish increased in growth EVEN FURTHER
Shows that they will not be impacted by OA.
Feeding rates also increase substantially under higher temp and CO2.
This suggests taht these animals, as long as supplied by food, can maintain their growth rates.
Calcification slightly decreases. This suggests that the animals are putting their energy into different areas.
They choose which one is more important- calcification or feeding and growth.
100
what are the combined effects of CO2, warming and invasive species?
calcium content reduced at high temperatures and CO2
no effect on some of the species
some survival reduced at high temperature and CO2
S balanoide species population strongly affected by combined effects of OA and rising temperatures
101
how does seasonal variation modify impacts of CO2 and warming?
Under ambient conditions, relative seasonal cycle for bioturbation. Much deeper in teh summer than they do in winter. This pattern breaks down under the warming scenario. These species respond to seasonal variation. But there are very few experiments that take seasonal variation into account.
In winter, specifically in OA, temp is colder, and CO2 is absorbed into the water much easier, the effects of OA are much worse for the organisms.
102
what are the combined impact on OA and hypoxia?
greater oxygen sensitivity of early life estuarine fish to low oxygen compared to low pH conditions.
it also reduces fitness of this species which may impact higher tropic organisms
103
what are the impacts of climate change and physical disturbance in terms of trawling?
Finding out how trawling of the soft sediment, on combination with the cliamte increasing, affects the behaviour of the organisms.
2 sites- one from high intensive trawling, and one with low history of trawling.
Went out and used a neocore. Brought up an enact square of sediment.
Incubated them under ambient and future conditions for 6 months.
Then measured biodivation activity, put sand on sediment surface and let the animals do their thing and mix the sediment with the cores.
Can measure the max an min depth to show how active the animals are.
Measured nutrient concentration, as that is an indication on how much they simulate activity.
Sieved all the animals out and identified the animals to know what organisms were in each sediment core.
104
how does macrofaunal diversity change, in terms of trawling intensity and climate?
Found that there was a reduction in overall species richness, from low to high intensity trawling, but only under the FUTURE cliamte conditions.
If you compare the boxes, you can see that there is also a change in overall community conditions. This was due to the cliamte rather than the trawling intensity.
105
what are the effects on macronutrients in trawling?
reduction in nutrient concentration under future climate and high intensity trawling.
future climate conditions have greater impact on macrofaunal communities and biochemical cycling than trawling frequency
106
why is the future climate worse than trawling activity/?
it is constant
| there are controls on certain areas. CC is everywhere and not specific
107
what are the 3 responses to OA?
synergistic, neutral or antagonistic.
these are dependent on the spaces or the physiological processes involved.
