Lecture 13

Question 1

Speed of ocean temperature rises

Answer 1

Rising by 0.1 degree Celsius per decade (1960-2009)

Question 2

Predictions of changes due to ocean temperature increase by 2100

Answer 2

Mora et al. 2013
Ocean surface temperature increased by 2-3 degrees Celsius
pH decline by 0.2 units
Oxygen concentration decrease by 2-4 units
Ocean productivity could decrease by 2% to 20%
Will affect all marine habitats
Effects greatest in surface waters and shallow habitats

Question 3

When is the real change in marine habitats expected to come?

Answer 3

2030
Marine habitats will enter new climate regime before terrestrial climate
Poorer countries will enter first

Question 4

Potential impacts in marine life: organismal level

Answer 4

change in body size, reproduction, primary productivity, habitats

Question 5

Potential impacts in marine life: population level

Answer 5

Changes in population growth, abundance, species distribution

Question 6

Potential impacts in marine life: community/ecosystem level

Answer 6

Changes in community structure, trophic interaction, biodiversity

Question 7

Potential impacts in marine life: fisheries/economics

Answer 7

Changes in fisheries catch, economics of fishing, fishery management

Question 8

Potential impacts in marine life: global issues

Answer 8

Human population growth, migration, development, food supply and energy prices

Question 9

Biogeographic shifts due to climate warming

Answer 9

Most species studied show poleward latitudinal shifts
However, some species show lower poleward distribution shifts than expected - they may be constrained by ‘essential’ habitat

Question 10

Heatwave in south east Indian ocean

Answer 10

2011
Wernberg et al. 2013
Caused massive shifts in abundance of local species

Question 11

Evidence of results of marine heatwaves increasing in frequency

Answer 11

Smale et al. (2019)
More and more coral bleaching
Decrease in seagrass density
Giant kelp biomass changes

Question 12

What causes “tropicalisation” of fisheries?

Answer 12

Poleward shifts and local abundance changes
Mean temperature of catch is increasing
(MTC = average inferred temperature preference of exploited species weighted by their annual catch)

Question 13

Temperature and body size

Answer 13

Increased temperatures lead to greater metabolic costs
As environmental temperature increases from lower critical temperature, there is a linear increase in growth until pejus temperature is reached, after which growth rate declines rapidly and ceases at the upper critical temperatures
Smaller body sizes are therefore expected at high temperatures

Question 14

What is phenology?

Answer 14

The study of the timing of life history events

Question 15

Climate change and phenology

Answer 15

• Climate determines the timing of seasonal marine events
• Warmer temperatures may shift life history events to occur earlier
• E.g. NE Atlantic zooplankton blooms produced earlier in warmer waters

Question 16

What is the match-mismatch hypothesis?

Answer 16

• Mismatch between prey and critical stages in their life history is known as the match-mismatch hypothesis
• Developed by David Crushing
• E.g Rhinoceros auklets in Japan - chicks grow faster and fledge successfully when fed on more anchovy, that in turn arrives earlier in warmer years