Theme D

Question 1

What is SST?

Answer 1

Sea surface temperature (top metre or so)

Question 2

What are the figures regarding how warm the oceans are?

Answer 2

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

Question 3

What makes the water warm up faster than air?

Answer 3

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

Question 4

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

Answer 4

90%

Question 5

How high was 2017’s OHC value?

Answer 5

• Equivalent to almost 700x chinas total annual electricity generation

Question 6

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

Answer 6

• 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

Question 7

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

Answer 7

Move, Adapt or Suffer consequences

Question 8

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

Answer 8

• 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

Question 9

Which fish specifically have decreased in abundance?

Answer 9

• Haddock and cod because they like cold

Question 10

Why don’t all fish move?

Answer 10

• 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

Question 11

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

Answer 11

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

Question 12

How do phytoplankton respond to environmental changes?

Answer 12

• 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

Question 13

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

Answer 13

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

Question 14

What is the problem associated with coral bleaching?

Answer 14

• 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

Question 15

Give the characteristics of cold water corals

Answer 15

• 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

Question 16

Give characteristics of Kelps

Answer 16

• 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

Question 17

How is pH measured and why is it worth acknowledging?

Answer 17

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

Question 18

What is the chemistry of ocean acidification?

Answer 18

• 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

Question 19

What happens when you decrease carbonate ions?

Answer 19

• 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)

Question 20

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

Answer 20

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

Question 21

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

Answer 21

• 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

Question 22

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

Answer 22

• > 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

Question 23

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

Answer 23

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

Question 24

What is CCD?

Answer 24

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)

Question 25

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

Answer 25

95% of marine animal species

Question 26

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

Answer 26

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

Question 27

Give some examples of calcifying organisms

Answer 27

- 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

Question 28

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

Answer 28

- 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)

Question 29

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

Answer 29

- 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.)

Question 30

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

Answer 30

- 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

Question 31

What is a potential mechanism for reversing ocean acidification?

Answer 31

- 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%

Question 32

What processes are essential for a functioning ecosystem?

Answer 32

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

Question 33

What processes are sediment infauna responsible for?

Answer 33

Sediment infauana = invertebrates living in sea bed 1. Nutrient flux 2. Bioturbtion 3. Movement

Question 34

What is another term for the sediment infauna?

Answer 34

Benthic communtiites

Question 35

What is bioturbation and its importance?

Answer 35

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

Question 36

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

Answer 36

- 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

Question 37

How is bioturbation measured?

Answer 37

- 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

Question 38

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

Answer 38

The Common brittle star

Question 39

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

Answer 39

- 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

Question 40

How are individual measurements scaled to ecosystem scales?

Answer 40

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

Question 41

Why is the order of species extinction important?

Answer 41

- 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

Question 42

How does biodiversity increase ecosystem function?

Answer 42

- 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

Question 43

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

Answer 43

- 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

Question 44

What are blue carbon ecosystems?

Answer 44

- 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