L13 Ocean Warming Flashcards
What are some general global trends in ocean warming?`
1960-2009 global increase in average sea temperature by 0.5 degrees per decade. less change than in terrestrial environments.
Predicted from now - 2100, SST increases 2-3 degrees. pH declines by 2.0, O2 conc decrease by 2-4% (as temp is key determining factor in O2 holding capacity) and ocean procuctivity decrease by 2-20%.`
How do cumulative effects of ocean warming impact life?
Effects of warming on life are lower in deep water habitats such as vents and seamounts, and greater in shallow environments such as reefs, shelves and mangroves.
Effects are experienced by all species groups.
How can effects of climate change be considered?
Regarding the time when local climate is consistently beyond the range of historic climate.
eg in 1x1degree cells in the atlantic, all years are expected to exceed current/usual temps by 2030. expect to see substantial biological impacts.
what predictions do global quantifications show?
annual means will have departures by 2050
Monthly means by 2100
Departures likely to be earlier in marine environments than terrestrial esp coral reefs, mangroves and seagrass beds.
Poorer countries experience departures and effects first
What is a different way of considering climate change?
Climate velocity
Pace of change in a region, spatially.
Shown on a graph with latitudes on y, and velocity in km/decade on x.
The distance a climate has travelled. eg 50 years ago, where was the climate we experience in Bristol now?
Can measure latitudional shifts - eg a 0 degree climate has shifted 150km/decade towards poles . Most climates have shifted 20km/decade towards poles.
Also can show seasonal shifts - eg in N hemisphere, spring temp shifted on average 5 days forward and in south autumn temp shifted 5 days backward. overall lengthening of summer and shortening of winter.
What causes climate to shift east and west?
Prevailing winds, currents and presence of land masses
What impacts can climate change have on marine life at different levels?
Organism - Change in body size, reproduction, primary productivity
Population - change in pop growth, abundance, species distribution
Community - change in trophic interactions and biodiversity
Fisheries - change in catch, eoconomics of fishing and fishery management
Globally - affects human pop growth, migration, development, global food supply, energy price.
What is a common response of organisms to climate change?
Most species show shifts in latitudinal distribution in response to climate change.
NE atlantic zooplankton - continuous recorded plankton data available from 1950s onwards, can map distributions of groups of copepod zooplankton. 4 groups of specied were observed to show northward shift - warm temperate pseudo-oceanic species, temperate pseudo-oceanic species, cold mixed water species and subarctic species. 1958-2005 strongest evidence
Which types of species would migrate latitudionally?
Species with no tight association with sea bed habitats for food, mating or recruitment. Phyto and zoo plankton is responding v rapidly.
How might species respond which are tied to the sea bed?
Local abundance shift, instead of latitudional shift.
What is an abundance response?
average correlation between temp and abundance in 1x1 degree cells.
72% species have a significant level of local abundance shift.
Strength of response associated with overall thermal prefernces - warm loving species increased locally, cold loving species declined.
How does local abundance shift affect marine communities?
Dramatic changes, loss of macro algae and increase in recruitment of tropical marine fish species.
Change of local climate facilitates recruitment that would normally fail in that region.
How have local abundance changes and latitudinal shifts affected composition of multispecies fishstock?
Changes to body size - warmer water holds less O2, future oceans less oxygenated, warmer water energetically more expensive to live in so fish require more O2. so metabolism is more costly, growth rates decline so max size smaller.
Analysis of 13 north sea stocks of 8 species support theory that warmer waters give smaller body size.
Dramatic implications - estimated by 2050, max body weight will have declined substantially by as much as 10%.
Describe a typical temp/growth rate relationship``
Tcl (critical lower temp) - Tp (pejus temp) near linear increase of growth rate.
just after Tp to Tcu (critical upper) decline in growth rate, as costs of growth are outweighed by energetic costs.
What is phenology
Study of life history events
