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Comparison of Phytoplankton Dynamics in the North Atlantic and the North Pacific

Comparison of Phytoplankton Dynamics in the North Atlantic and the North Pacific. North Pacific. North Atlantic. Temporal standard deviation of chlorophyll (mg m -3 ). Temporal standard deviation of chlorophyll (mg m -3 ). Temporal standard deviation of carbon biomass (mg m -3 ).

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Comparison of Phytoplankton Dynamics in the North Atlantic and the North Pacific

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  1. Comparison of Phytoplankton Dynamics in the North Atlantic and the North Pacific

  2. North Pacific North Atlantic Temporal standard deviation of chlorophyll (mg m-3) Temporal standard deviation of chlorophyll (mg m-3) Temporal standard deviation of carbon biomass (mg m-3) Temporal standard deviation of carbon biomass (mg m-3)

  3. North Atlantic Box 19ºW - 21ºW, 49.5ºN - 50.5ºN North Pacific Box 144ºW - 146ºW, 49.5ºN - 50.5ºN Chlorophyll Phytoplankton Carbon from Particulate Backscatter (Behrenfeld et al., 2005)

  4. North Atlantic Box 19ºW - 21ºW, 49.5ºN - 50.5ºN North Pacific Box 144ºW - 146ºW, 49.5ºN - 50.5ºN Chl:C Ratio

  5. Observed Chl:C ratios at OSP

  6. Full Time Series Pacific: 160ºW-140ºW Atlantic: 20ºW-40ºW Chlorophyll Phytoplankton Carbon from Particulate Backscatter (Behrenfeld et al., 2005)

  7. Full Time Series Pacific: 160ºW-140ºW Atlantic: 20ºW-40ºW • Why are summer Chl:C ratios lower in the Pacific than the Atlantic? • More light in the Pacific? • Stronger nutrient stress in the Pacific? Chl:C Ratio

  8. Chlorophyll:Carbon Ratio Observed Chl:C Growth Irradiance Ig Pacific Pacific Atlantic Atlantic Calc. Chl:C = f(Ig) Atlantic Geider Model: • max = b / (1 + b • a • I / (2 • Pcmax)) + a • b = 0.038 mg Chl / mg C, a = 0.002 mg Chl / mg C • a = 3.0E-5 gChl-1 gC W-1 m2 s-1, Pcmax = 3.0E-5 s-1 • I = growth irradiance (W m-2) Pacific

  9. Atlantic calculated observed Pacific calculated observed Chlorophyll:Carbon Ratio

  10. Atlantic Pacific Chlorophyll:Carbon Ratio Atlantic No growth limitation calculated observed Strong growth limitation Pacific Nutrient (and Temperature) Limitation Index: • f(N,T) = obs / max • obs = observed Chl:C • max = calc. max. Chl:C from Geider, assuming no nutrient limitation calculated observed

  11. Atlantic Pacific Chlorophyll:Carbon Ratio Atlantic No growth limitation calculated observed Strong growth limitation Pacific Pacific calculated Atlantic observed Fan et al., subm.

  12. Soluble Fe Flux (Fan et al., submitted)

  13. Opal Flux (Wong & Matear, 1999) Ocean Station P, Sediment Trap Data

  14. Particulate Backscatter (Stramski et al., 2004) “More recently, it was suggested that in typical non-bloom open ocean waters, phytoplankton or all the microorganisms account for a relatively small fraction of particulate backscattering, and that most of the backscattering may be due to non-living particles, mainly from the submicron size range (Morel & Ahn, 1991; Stramski & Kiefer, 1991). The potential role of small-sized organic detritus as a major source of backscattering was emphasized but the significance of minerals was not excluded (see also Stramski, Bricaud, & Morel, 2001). (…) The optical impact of coccolithophorid phytoplankton (coccolithophores) can be, however, very important (Balch, Kilpatrick, Holligan, Harbour, & Fernandez, 1996). These phytoplankton species produce calcite scales called coccoliths that are characterized by a high refractive index. It was estimated that even outside the coccolithophore bloom, 5–30% of the total backscattering could be associated with coccoliths (calcite plates detached from cells) and plated cells.”

  15. Coccoliths (Balch et al., 2005)

  16. Mesozooplankton (Goldblatt et al., 1999)

  17. Bacterial Biomass (Sherry et al., 1999)

  18. Full Time Series Averaged: 160ºW-140ºW Averaged: 20ºW-40ºW Maximum Chl:C Ratio Nutrient Limitation Factor

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