Transcript Climate change… - Center for Microbial Oceanography

Weekly Theme: The Ocean as a Microbial Habitat
Daily Theme: MICROBIAL OCEANOGRAPHY: PROJECTIONS,
DYNAMICS, AND THE HUMAN DIMENSION
M J Perry Lecture: “How might projected changes to the ocean
influence plankton biology?
C-MORE, 4 June 2010
Driver –– Mechanism –– Effect
Examples
Drivers:
What are some predicted changes to
ocean that may influence plankton biology?
• Temperature
Drivers of plankton biology:
• Temperature
• Physical – temperature & gas solubility – less O2 and less CO2 uptake,
stratification and nutrient flux, winter mixed layer depth
• Arctic ice melt – reduction in albedo; FW enhanced stratification
• direct biological – rates, resource availability, size, biogeogr. provinces
• Circulation – slower, less ventilation; more O2 min. zones; more denitrifrication
• pH – shift equilibrium for CaCO3 (aragonite). Tropical & deepwater corals –
ecosystem habitat structure. Chemistry – borate & trace metal bioavailability.
• Eutrophication – excess nutrient and organics; nutrient ratios (no Si); species
shift (HABS?); dead zones; fish nursery grounds.
• Less O2 –open & coastal ocean: more gellies (low metabolism /fake giant)?
• Habitat alteration – structure (SAV, corals); dead zones; engineering structures
• Overfishing – change size structure.
• Energy extraction – oil; wind and tide
• Invasive species
• Chemicals – endochrine mimickers; plastics; other toxins
• Rainfall on land – weathering Si & P; desertification – Fe dust
Temperature
Rates
growth rates
development rates
reproductive rates
Thermal boundaries and biogeographic provinces
“Community assembly” – not just one species changes in
response to thermal boundary shift – changes in resource
availability to other trophic levels (prey size)
Phenology (timing) – Cushing’s Match/Mismatch Hypothesis
Increase in temperature
Direct effect :
rate of reactions are temperature dependent:
Arhenius equation: k is rate constant, A is pre-exponential or freq. of
collision factor, EA is activation energy, R is gas constant, T is temp.
What rates?
diffusion – that might be good for a cell, diffusion of nutrients
enzyme rates –
where T is ºK
Q10 is typically 2 – 3 for enzyme reactions
Temperature increases rate of enzymatic reaction, but there is an
upper limit – thermal deactivation.
Temperature increases growth
rate of a phytoplankton species,
but there is also an upper limit
for a given species – thermal
deactivation and death.
Classic paper: Eppley. 1972.
Fishery Bull. 70: 1063
Composite curve of
maximal growth rates
for number of
phytoplankton species.
something will grow
Curve sets an upper limit to
growth rate as a function of
temperature. Data from many
species in culture.
Two notes:
* Cultures grown in 24 hours of
light, so in situ rates will be
lower.
* Growth rate is k (doubling/d)
Classic paper: Eppley. 1972. Fishery Bull. 70: 1063
Egg hatch rate, development rate and growth rate of zooplankton
increase as a function of temperature – within tolerance range.
Egg hatch rate
Juvenile development rate
Weight-specific growth rate
Hirst & Bunker. 2003. L&) 48: 1988
Increase in temperature will increase growth rate of a species,
until critical temperature is exceeded. That lead to a
change in geographic boundaries in NE Atlantic:
warm water zooplankton moved north.
ASIDE: Biogeographic provinces. Promoted by Longhurst; they have been
defined based on species assemblages, ocean color, SST, MLD, and more.
Broad brush (few provinces) or fine brush (many little provinces).
Provinces defined on ocean color, with soft edges.
Oliver & Irwin analyzed change in
area of biogeographic provinces
over time.
Province boundaries are plastic:
expand and contract in response to
changing drivers (example for Eq.
Pacific).
Boundary edges most susceptible
first.
2008. Geophysical
Research Letters: 35
Change in sea surface temperature and 9-10ºC isotherm in North Atlantic.
Beaugrand et al. 2008. Ecology Letters 11: 1157.
Community reassembly
Warmer temperatures .
Increased biodiversity of copepods.
Smaller copepods.
Less valuable resource to cod.
Community reassembly: Change in one
functional species (prey) could lead to
indirect change in province of another
(predator/cod)
Beaugrand et al. 2010. PNAS 22: 10120 (sponsored by D. Karl)
Why might smaller sized zooplankton dominate in warmer waters?
Why might smaller sized zooplankton dominate in warmer waters?
More stratification  less nutrient flux
Less nutrients  smaller phytoplankton
Several consequences of warmer temperature:
decrease in nutrient flux – smaller phytoplankton cells
FOOD WEB consequence:
scaling of size for many
prey/predator interactions
leads to decrease in size
of zooplankton (10:1 rule)
Why might smaller sized zooplankton dominate in warmer waters?
More stratification  less nutrient flux
Less nutrients  smaller phytoplankton
Several consequences of warmer temperature:
decrease in nutrient flux – smaller phytoplankton cells
FOOD WEB consequence: :
scaling of size for many prey/predator interactions leads to
decrease in size of zooplankton
CARBON CYCLING consequence: less carbon flux
- small cells have very low sinking rates (Stokes Law);
- respiration scales both with body size and temperature;
- Microbial Loop consumption w/ little net production.
Phenology – changes in timing (match/mismatch of key functions).
Some organisms cue to light, others temperature, others food.
Timing of seasonal peaks
for two regimes.
Inter-annual variability of
seasonal peak.
Edwards & Richardson. 2004. Nature 30: 881
Changes in timing of seasonal peaks (in months) for 66 taxa spanning 3
trophic levels over 45-yr period from 1958 to 2002 relative to timing of
seasonal peak in 1958. For each taxon, linear regression in ‘b’(prev. slide) .
Negative difference indicates seasonal cycles are becoming earlier.
Negative
Positive
Edwards & Richardson. 2004. Nature 30: 881
Why is timing important: growth rate and reproduction are a
function of food. Example for copepod egg production.
µg Chl/ L
Hirst & Bunker. 2003. L&) 48: 1988
Another example of change in timing: US west coast.
Upwelling favorable winder from north drive transport of cold
nutrient rich water to surface.
SST (surface temperature)
Chlorophyll
Anomalous southward shift of jet stream – delayed transition
Nitrate and chlorophyll off Oregon 2005.
Filled = 2005; Open = climatological mean.
Note effect of 2 month delay in onset of upwelling.
Nitrate
Chlorophyll
Barth et al. (2007)
PNAS 104: 3719
2005 - worst year on record for Farallon Island auklets
(42 km west of San Francisco)
#young/breeding-pair
Reduced phytoplankton –> reduced zooplankton –> reduced fish
Mean productivity = 0.70 young/breeding pair
Borrowed from T. Straub talk
Sydeman (PRBO)
Percent difference in sound absorptivity in seawater between
0.01 and 100 kHz for a decrease in pH from 0.15 to 0.6 units.
Lower pH  less sound absorption at lower frequencies.
Acidification of media containing various Fe compounds decreases
the Fe uptake rate of diatoms and coccolithophores to an extent
predicted by the changes in Fe chemistry. A slower Fe uptake by a
model diatom with decreasing pH is also seen in experiments with
Atlantic surface water. The Fe requirement of model phytoplankton
remains unchanged with increasing CO2.
Shi et al. 2010. Science 237: 676
Eutrophication
Global distribution of >400 systems with eutrophication driven dead zones.
Diaz, et al. (2008). Science 321: 926
(note color scale: human foot print)
Over 40% US estuaries are degraded from eutrophication
Boyer et al. 2002. Biogeochemistry 57/58:137
26
Eutrophication increases as human footprint increases
human waste
more people,
more sewage, etc.
human population
as of Nov 3, 2009:
308 M people in US
6,800 M worldwide
27
Mississippi delta dead zone – region of ~ 20 x 104 km2 of
hypoxic bottom water. Hypoxia is “loose” definition ~
of 3.0–0.2 ml O2 L-1 (consensus 1.4 ml O2 L-1 ). Hypoxic
& dead zones are doubling/decade.
Rabalais et al., 2002
Eutrophication = excess nutrients => phytoplankton blooms
more light attenuation  decrease SAV (structure); bad for
visual feeders
hypoxic  bad for organisms with high metabolic rate
Jelly plankton volume
Jelly carbon plankton volume, scaled to
crustacean carbon/volume
Invasive species
Mnemiopsis leidyi
Introduced into the Black Sea in 1982, presumably in
ballast water; predator on zooplankton
Beroe ovata
Later introduced into the Black
Sea, in ballast water; predator
on Mnemiopsis. Here with
mouth open.
http://www.imagequest3d.co
Changing circulation patterns can introduce new species.
Arrows are
glaciations;
shaded area
indicates prescence
of Neodenticula
seminae in ice cores
Energy extraction
6 May 2010
4 June 2010
Projected 5 June 2010
Projected 6 June 2010
Projected 7 June 2010
Drivers of plankton biology:
• Temperature
• Physical – temperature & gas solubility – less O2 and less CO2 uptake,
stratification and nutrient flux, winter mixed layer depth
• Arctic ice melt – reduction in albedo; FW enhanced stratification
• direct biological – rates, resource availability, size, biogeogr. provinces
• Circulation – slower, less ventilation; more O2 min. zones; more denitrifrication
• pH – shift equilibrium for CaCO3 (aragonite). Tropical & deepwater corals –
ecosystem habitat structure. Chemistry – borate & trace metal bioavailability.
• Eutrophication – excess nutrient and organics; nutrient ratios (no Si); species
shift (HABS?); dead zones; fish nursery grounds.
• Less O2 –open & coastal ocean: more gellies (low metabolism /fake giant)?
• Habitat alteration – structure (SAV, corals); dead zones; engineering structures
• Overfishing – change size structure.
• Energy extraction – oil; wind and tide
• Invasive species
• Chemicals – endochrine mimickers; plastics; other toxins
• Rainfall on land – weathering Si & P; desertification – Fe dust