i Largest scales oceanic inventories Residence time kyr you conveniently ignore all that stoichiometric variability Gideon Henderson GEOTRACES mtg London Dec ID: 647655
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Slide1
Theme 1: Biological uptake and trace element bioavailabilitySlide2
i) Largest scales: oceanic inventories
Residence time (
kyr
)
‘…you conveniently ignore all that stoichiometric variability…’ (Gideon Henderson, GEOTRACES mtg., London, Dec 2015)
~
circ
Trace metals have differential availability (relative to biological demands) within the modern ocean
Figure adapted from Moore et al. (2013) Nature Geo.
‘Conservative’
‘Nutrient like’
‘Scavenged/hybrid’
Recognise it and embrace it… (e.g. Sarmiento et al. 2004 Nature; Weber and Deutsch 2012 Nature; DeVries and Deutsch 2014 Nature Geo.; Galbraith and Martiny 2015 PNAS)
1. How does stoichiometric plasticity connect to trace metal distribution and inventories?
Mark Moore
presentationSlide3
Fe‘
(inorganic)FeDFB (Fe-siderophore)
Uptake rate / [Fe Sub]
Surface area normalized uptake (K
in/S.A) is similar among all Euks for Fe’ and for FeDFB.
But Fe’ >> FeDFB (x
1000)Uptake of Fe‘ and siderophore bound Fe (FeDFB)
2. How
much do we know about the different TE acquisition systems of microorganisms? 3. What ‘modes’ of metal (M) uptake dominate in different natural systems?
Yeala Shaked presentationSlide4
N and Fe stress markers in
Prochlorococcus:Successfully track biome shifts (N lim, Fe lim)Highlight areas of possible co-limitation
Saito et al. data, Chappell presentation
4. How important are co-limitations?Slide5
high Fe requirement & potential functional complementary of these metals
5. Can we consider the influence of multiple metals on organisms?Ho presentationSlide6
Fe Stress Gene Expression from Community Incubations (Chappell, Fitzsimmons,
Ohnemus unpublished)Expression indicative of Fe stress is evident in most treatments. Samples for expression analysis taken at 72hrs 6. How can molecular and biochemical info improve
our knowledge?Chappell presentationSlide7
7. How do we improve our understanding of TE bioavailability?
8. What is the role of TE speciation (redox, organic, and physical) for their uptake and bioavailability (link with Theme 2)? 9. Can we connect entire food-web structure with TE uptake and inventories?10. Can we capture and understand temporal variations (early stage vs. decline of the bloom) and spatial variations?11. How available are regenerated TEs (link with Theme 3)?12. How can biological and biogeochemical processes be incorporated into models?13. How do we connect large GEOTRACES datasets to their influence on the biological pump? Theme 1: Biological uptake and trace element bioavailability1. How does stoichiometric plasticity connect to trace metal distribution and inventories?2. How much do we know about the different TE acquisition systems of microorganisms? 3. What ‘modes’ of metal (M) uptake dominate in different natural systems?4. How important are co-limitations?5
. What are the interactions within an organism for multiple metals?6
. How can biochemical and molecular information to improve our knowledge? Slide8
The bioavailability envelope:
comparing Fe substratesMore bioavailable Fe substrates
Fe’
FeDFB
Less
bioavailable
Fe substrates
l
og (k
in
/S.A)
Yeala
Shaked presentation