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Ecosystems and Sustainability > Theme D > Flashcards

Theme D Flashcards

1
Q

What is SST?

A

Sea surface temperature (top metre or so)

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2
Q

What are the figures regarding how warm the oceans are?

A

For most of the oceans, the warmest decade ever recorded was the most recent, steady warming trend of a tenth of a degree per decade

The 20 years up to 2017 included 18 of the hottest global annual SSTs ever recorded

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3
Q

What makes the water warm up faster than air?

A

It take up heat 4000 times more effectively than air as it is very dense

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4
Q

What percentage of the heat generated by anthropogenic warming has been absorbed by the oceans?

A

90%

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5
Q

How high was 2017’s OHC value?

A
  • Equivalent to almost 700x chinas total annual electricity generation
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6
Q

How do El Nino events lead to smaller Ocean Heat Content (OHC)

A
  • El Nino causes warming of surface ocean temps
  • Warmer surface waters lead to increased heat transfer from deeper ocean layers to the surface atmosphere (Ocean-atmosphere coupling)
  • Warmer surface waters release heat that was previously stored in the deeper ocean layers
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7
Q

What are the three options to respond to warming as a marine organism?

A

Move, Adapt or Suffer consequences

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8
Q

What is the evidence for organisms that ‘move’ as a response to warming?

A
  • Moving is the first thing fish do
  • Studies have counted and tracked every fish and then carried out species level analysis
  • Northern affinity fish abundance decreases with warming as they are adapted for cold
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9
Q

Which fish specifically have decreased in abundance?

A
  • Haddock and cod because they like cold
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10
Q

Why don’t all fish move?

A
  • Temp isn’t the only thing that dictates where a fish lives, many are tied to specific habitats
  • Oceanographic structure can be important, norther doesn’t always mean cooler

-Shifting deeper isn’t alway possible

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11
Q

What is meant by the leading edge and trailing edge of species range?

A

Leading edge = advancing boundary of a species’ distribution
Trailing edge = rear or retreating boundary of a species’ distribution

At trailing edge we may expect species to die as it gets too warm
Other populations can expand in to waters that used to be too cold but are now suitable

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12
Q

How do phytoplankton respond to environmental changes?

A
  • rapidly, the timing of phytoplankton blooms has advanced much faster than that of plants on land
  • animals that feed on phytoplankton e.g. larval fish have advanced their key advanced even faster than the phytoplankton
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13
Q

What is the only problem with phytoplankton being able to adapt quickly?

A
  • there’s different responses based on trophic levels can lead to temporal mismatches which can lead to affected food webs
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14
Q

What is the problem associated with coral bleaching?

A
  • Bleaching itself isnt lethal but they need time to recover between bleaching events
  • This gap is shortening giving less time to recover and less chance of mortality
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15
Q

Give the characteristics of cold water corals

A
  • Create important habitats
  • Reefs in scotland -Desmophyllum
  • Provide rich feeding grounds and important breeding areas
  • Models project decrease of 28% to 100% in suitable habitat
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16
Q

Give characteristics of Kelps

A
  • Foundation species
  • V.productive and diverse
  • Diff. kelp species around the world respond differently e.g. extinction, range expansion, abundance decrease etc.
  • Low latitudes more likely to cause extinction as water just gets too warm
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17
Q

How is pH measured and why is it worth acknowledging?

A

pH is a measure of H+ concentrations and its a logarithmic scale
So a small change is actually huge
- when you plot pH in terms of H+ ions rather than pH units the increase is much more steep

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18
Q

What is the chemistry of ocean acidification?

A
  • Some of the C02 entering the sea remains as gas but it can also be taken up by marine photoautotrophs through photosynthesis
  • remaining C02 combines with water and forms carbonic acid
  • When carbonic acid is dissolved in water it dissociates into Hydrogen ions and Bicarbonate ions
  • Most hydrogen ions will combine with carbonate ions creating bicarbonate ions which reduces the pool of carbonate ions in sea water
19
Q

What happens when you decrease carbonate ions?

A
  • Many marine organisms build hard parts out of calcium carbonate
  • Various forms of calcium carbonate are used e.g. aragonite, calcite etc.
  • Organisms need to extract calcium and bicarbonate ions from seawater to form calcium carbonate (this releases C02 and water in the process)
20
Q

What is the positive feedback loop with the production of calcium carbonate?

A
  • Producing calcium carbonate emits more c02 in to the water, which creates carbonic acid and further reduces the pool of carbonate ions
21
Q

How hard is it for organisms to produce these hard structures?

A
  • Seawater chemistry influences how difficult organisms will find it to produce their calcium carbonate hard parts
  • Can be quantified with the saturation states of different forms of calcium carbonate
22
Q

What are the results you would conclude from looking at the saturation state equation?

A
  • > 1 is considered supersaturation so shell building is easy and structures will stay intact
    < 1 is considered undersaturation which favours dissolved ions and its difficult to build anything with solid calcium carbonate, easily broken down by seawater

Coral reefs need a saturation state significantly above 1 need at least 3.25

23
Q

In what ways are we approaching a ‘hot house period’ regarding oceanic pH

A

Current surface pH is lower than it has been for at least 2 MY so we don’t know what the modern effect on marine life is going to be

24
Q

What is CCD?

A

Calcium compensation debt , if you go well below it calcium structures start to dissolve

  • There is usually a balance between C02 in sea (acidification) and mineral input from weathering (alkalinity)
25
Q

What percentage of marine species went extinct in the end-permian mass extinction?

A

95% of marine animal species

26
Q

What is dooming evidence that calcifying species struggle to adapt in response to ocean acidification?

A

Most organisms so far have demonstrated reduced calcification at increased pC02 and consequent decreased carbonate ions and calcium carbonation state and pH

27
Q

Give some examples of calcifying organisms

A
  • Calcifying holoplankton
  • Coccolithophores (single celled phytoplankton important in fixing carbon)
  • Pteropods (‘sea butterflies’ that have a calcium carbonate shell made of aragonite)
  • Calcifying benthos (things in the sea bed, invertebrates such as molluscs, sponges, crustaceans etc.)
    E.g. mussels, oysters which have been affected as their calcification rates have been shown to decline by 25% in mussels and 10% in oysters
28
Q

How are developmental processes, behaviour and reproduction effected by calcification?

A
  • Studies in sharks, most threatened in marine groups due to slow adaption
  • Blood and tissues can be acidified due to blood having same osmic polarity of seawater
  • Acidification can also affect olfactory ability in sharks and rays to detect predators, food and mates (tested in smooth dogfish where they didnt move towards prey with more acidic water)
29
Q

What are the limitations of studying the effects of ocean acidification on developmental processes, behaviour and reproduction?

A
  • Studying one single species so no interactions
  • Short exposure to low pH means theres no adaption- just a shock
  • No consideration of multiple generation effects
  • Limited number of treatments and often high pC02 treatments are quite extreme
  • Hard to adjust pH in a way that accurately effects ocean chemistry
  • Adjusting just pH may not reflect interactions with other stresses (some have with ocean warming for e.g.)
30
Q

What are some examples of natural experiments that can be used to look at ocean acidification effects?

A
  • vents that pump into the ocean to make it more acidic, you can see the abundance of different species at different distances from these vents
    E.g. organisms with aragonite skeletons absent at stations with mean aragonite saturation of 2.5 or less
31
Q

What is a potential mechanism for reversing ocean acidification?

A
  • Pumping sodium hydroxide into the corals
  • Used on the coral reefs:
  • ⅙ of the experimental alkalinity was taken up by the reef community and the aragonite saturation state increased by about 0.4
  • Corals responded with net gain of 7%
32
Q

What processes are essential for a functioning ecosystem?

A

Photosynthetic activity
Nutrient fluxes
Sediment mixing
Purification e.g. clams filter water

33
Q

What processes are sediment infauna responsible for?

A

Sediment infauana = invertebrates living in sea bed

  1. Nutrient flux
  2. Bioturbtion
  3. Movement
34
Q

What is another term for the sediment infauna?

A

Benthic communtiites

35
Q

What is bioturbation and its importance?

A

the physical effects of animals on their substratum e.g. particle reworking and ventilation
- no oxygen in soils without and primary productivity would reduce

36
Q

What is effecting sediment mixing and nutrient cycling and why is it important?

A
  • Feeding,defecation and burrowing ventilates the sediment by flushing gallery with water so things can survive
  • threatened by human activities such as offshore wind, fishing - anything that affects the seabed
37
Q

How is bioturbation measured?

A
  • Luminophores are natural sediments treated with a dye so they fluorescence in UV light
  • spread across the sea bed and vertical placement is measured
  • Can compare bioturbation between different ecosystems and organisms
38
Q

What is a key organism in the UK which plays a big role in bioturbation?

A

The Common brittle star

39
Q

How is PET/CT imaging used to look at processes such as bioturbation?

A
  • Provides 3D structural information and temporal dimension to look at flow dynamics
  • Looked at the lugworm which pumps water into the burrow and ejects water through the sediment in the process of bioirrigation as it feeds and moves
  • Data turned in to visual analysis + quantified
40
Q

How are individual measurements scaled to ecosystem scales?

A
  1. Define an ecosystem level metric relevant to ecosystem functioning
  2. Effects on Ecology
    - species richness and diversity?
    - species body size? mobile? etc.
  3. Experimentally peturb the system
    - using computer systems to predict the effects of biogenic mixing depth of losing species for example for bioturbation
    - can look at extinction scenarios
41
Q

Why is the order of species extinction important?

A
  • The loss of certain species can disrupt these relationships and have cascading effects on the entire ecosystem (keystone species)
  • The order of species extinction can determine which functional roles are lost first, potentially amplifying the impacts on ecosystem dynamics
42
Q

How does biodiversity increase ecosystem function?

A
  • Increasing diversity increases the chance that important functions will be delivered
  • It can increase complementarity through functional redundancy
  • Increases the chance that important rare species are present
43
Q

How do ecosystem functions underpin the ecosystem services we depend on?

A
  • Nutrient cycling encourages growth
  • Climate regulation
  • Fisheries
  • Wildlife
  • We need to understand which we value the most as there are trade-offs between and we cannot maximise all of them
44
Q

What are blue carbon ecosystems?

A
  • coastal and marine habitats that have the ability to sequester and store large amounts of carbon dioxide e.g. mangroves and salt marshes
  • account for more than 50% of global carbon burial
  • Is meant to be a natural climate solution but if it doesnt work its seen as a ‘low regret strategy’ as preserving it is so important for so many other processes e.g. mangroves in coastal protection from flooding

Ecosystems and Sustainability (7 decks)

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