How the Ecumenical Iron Hypothesis Emerged from Ocean Station P Data. Charlie Miller Prof. Emeritus of Oceanography Oregon State University

Transcription

1 How the Ecumenical Iron Hypothesis Emerged from Ocean Station P Data Charlie Miller Prof. Emeritus of Oceanography Oregon State University

2 In High-Nitrate-Low-Chlorophyll oceanic ecosystems, phytoplankton cell size is restricted by iron limitation. The small cells are accessible to grazing by protists. The high growth potential of protists ensures they will always overtake and suppress increases in phytoplankton stock. Strom, Miller & Frost (2000)

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5 Seasonal production cycling appears in the biomass of mesozooplankton

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8 Fifth Copepodite

9 OSU technicians, aboard Harold P. Batchelder Martha Clemons Richard Conway Net Sampling to 2000 m CCCG Quadra

10 Limited-mixing and copepod-grazing hypothesis proposed for test as the SUPER Project

11 SUPER 1 and 2: The IRON hypothesis enters here. > Solubility of Ferric hydroxide (Fe(OH) 3 ) in seawater is ~0.5 nanomolar, less than 10-9 moles/liter. > John Martin was asked to join us. He replied, No, too busy with Vertex. > John Reuter (Portland State U.) and Don Anderson (now WHOI) proposed an iron enrichment experiment. > NSF said project too big. Cutting back, we went with testing grazing (we are grazer/grazing experts). Oops.

12 RV Wecoma Two SUPER cruises, May & August 1984

13 SUPER Group: Kenneth L. Denman IOS Charles B. Miller OSU Ann E. Gargett Patricia Wheeler David L Mackas Beatrice Booth UW Nicholas Welschmeyer Bruce W. Frost Harvard Michaek R. Landry Joyce Lewin Carl J. Lorenzen Mary Jane Perry Michael Dagg

14 1. Mixing had the long established limitations

15 Bouyancy frequency, calculations by Ken Denman and Ann Gargett

16 2. From Beatrice Booth: Phytoplankton in the oceanic Gulf of Alaska are almost all very small

17 3. Copepods distribute in the two upper mixing layers: Mackas and Sefton sampling from the CCCG Parizeau Note the new species

18 Fifth Copepodite

19 4. Welschmeyer & Lorenzen chlorophyll-budget technique

20 5. Most grazing is by microzooplankton, by protists d % 31.1% 7.3%

21 6. Neocalanus plumchrus were not eating phytoplankton, but they were growing. The progression in May of copepodite stage composition demonstrated that. Miller and Nielsen

22 Back to sea: Super 3 and 4, 1987 Super 5 and 6, 1988

23 Bruce Frost modelng in Seattle RV T. Washington Charlie Miller Pat Wheeler Mike Landry Nick Welschmeyer Tom Powell Mike Dagg Suzanne Strom and many more Parizeau Dave Mackas

24 1. Strom & Welschmeyer 1991

25 2.

26 3. Wheeler and Kokinnakis

27 4. Copepods = 1 N. plumchrus C5 per liter Landry and Lerner-Fournier

28 5. In 1987 John Martin (and Fitzwater,1988) reappeared in our lives:

29 Tests: SERIES Ironex-type mid-ocean iron addition 2002 (not shown) Roberta Hamme et al. (2010) Right: Mt. Kasatochi (a) ash deposition & (c) resulting phytoplankton bloom

30 6. irradiance Nitrate So, back to weather- ship data to generate models. mixed layer depth temperature Bruce Frost (1987, 91, 93) P vs. I

31 m chlorophyll protist biomass primary production Mixed layer detritus

32 Lots of models beside Frost s, for example: Fasham, MJR (1995) Variations in the seasonal cycle of biological production in subarctic oceans: a model sensitivity analysis. Deep-Sea Res. 42: Denman, KL and Peña, MA (1999) A coupled 1-D biological/physical model of the northeast subarctic Pacific Ocean with iron limitation. Deep-Sea Res. II, 46: [and several others by Ken and Angelica]

33 7. Strom, Miller & Frost (2000) surface What sets lower limits to phytoplankton stocks in high-nitrate, low-chlorophyll regions of the open ocean? MEPS 193:

34 7. Strom, Miller & Frost (2000) 1. Protists in the model ( Z ) graze the phytoplankton to nearly zero, unless feeding thresholds are applied. Frost s formulation assumed positive thresholds. 2. Data then available for protists (11 studies) showed NO food-availability thresholds for feeding by protists.

35 7. Tintinnopsis fed Isochrysis Verity (1985) Prey Concntration, µg carbon/liter

36 7. Answers: 1. Newer data do (maybe) show grazing thresholds for microherbivores (Paffenhofer, Sherr & Sherr (2007): Lessard & Murrell (1998): Sargasso field dilution experiment

37 7. Answers: 2. Switching by microheterotrophs (Z) to eating each other at low phytoplankton stocks (P): Lotka-Volterra prey-predator cycle: dp/dt = ap PZ, (a=0.69 d -1 ) P increase = growth grazing dz/dt = 0.02PZ - 0.5Z Grazer = grazing predation increase

38 7. Answers: 2. Switching by microheterotrophs (Z) to eating each other at low phytoplankton stocks (P): Lotka-Volterra prey-predator cycle: dp/dt = ap PZ, (a=0.69 d -1 ) P increase = growth grazing dz/dt = 0.02PZ - 0.5Z 0.03Z 2 Grazer = grazing predation cannibalism growth

39 CCCG Vancouver Hang on Martha