Primary Production in the Ocean

Transcription

1 Primary Production in the Ocean A global composite of sea surface chlorophyll concentration Oligotrophic gyre (LNLC) Seasonal Phytoplankton blooms Coastal Upwelling High-nutrient, low chlorophyll (HNLC) seawifs.gsfc.nasa.gov/seawifs/images/seawifs_gallery.html

2 Examples of the larger phytoplankton Coccolithophorid Dinoflagellate Diatom Diatom

3 Atmosphere Incident Light Biological Pump O 2 CO 2 Euphotic zone Phytoplankton (no change in ALK net decrease in pco 2 ) O 2 N, P, Si, trace metals CO 2 Zooplankton Bacteria Organic Matter Aphotic Zone Vertical mixing, advection Particle sinking, downward transport of DOM OM decomposition N, P, Si, trace metals CO 2 O 2

4 Law of the Minimum - Liebig's Law Justus von Liebig, generally credited as the "father of the fertilizer industry", formulated the law of the minimum: if one crop nutrient is missing or deficient, plant growth will be poor, even if the other elements are abundant. Liebig likens the potential of a crop to a barrel with staves of unequal length. The capacity of this barrel is limited by the length of the shortest stave (in this case, phosphorus) and can only be increased by lengthening that stave. When that stave is lengthened, another one becomes the limiting factor. For Phytoplankton 1)Light 2)Macronutrients (N, P) 3)Micronutrients (Fe, Zn)

5 Behavior of Light in the Sea 1)Exponential decrease in intensity with depth (z) I z = I 0 x e -kz 2) Preferential absorption in the red-end of the spectrum

6 High light adapted Low light adapted P = P max x I/(I+k I ) High light adapted Low light adapted

7 Sverdrup (1952) Net growth = dp - dr At the compensation depth (D c ) Net growth = 0, dp = dr For an individual phytoplankton cell The critcal depth(d cr ) is defined such that When the mixed layer depth (mld) < D cr, a phyto plankton bloom can occur

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10 Onset of nutrient limitation Onset of light limitation

11 Major Coastal Upwelling Zones A global composite of sea surface chlorophyll concentration Coastal Upwelling seawifs.gsfc.nasa.gov/seawifs/images/seawifs_gallery.html

12 Herbland & Le Bouteiller (1981) J. Plank. Res.

13 Direction reversed in southern hemisphere

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15 Martin et al. Fe studies in subarctic N. Pacific A global composite of sea surface chlorophyll concentration HNLC HNLC High-nutrient, low chlorophyll (HNLC) seawifs.gsfc.nasa.gov/seawifs/images/seawifs_gallery.html

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17 Martin et al. (1989) Deep-Sea Res.

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21 Large-Scale Fe Fertilization Experiments A global composite of sea surface chlorophyll concentration HNLC HNLC High-nutrient, low chlorophyll (HNLC) seawifs.gsfc.nasa.gov/seawifs/images/seawifs_gallery.html

22 Boyd, P. W., et al. (2000) A mesoscale phytoplankton bloom in the polar Southern Ocean stimulated by iron fertilization. Nature 407:

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25 Atmosphere Incident Light Biological Pump O 2 CO 2 Euphotic zone Phytoplankton (no change in ALK net decrease in pco 2 ) O 2 N, P, Si, trace metals CO 2 Zooplankton Bacteria Organic Matter Aphotic Zone Vertical mixing, advection Particle sinking, downward transport of DOM OM decomposition N, P, Si, trace metals CO 2 O 2

26 Alldredge and Silver (1988) Prog. Oceanogr.

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29 From W. Deuser

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