The Marine Food Webs 1)What regulates a planktonic food web? I)Light II)Nutrients III)Importance of the Type of Nutrient IV)Size and Export V)Food Web.
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Presentation on theme: "The Marine Food Webs 1)What regulates a planktonic food web? I)Light II)Nutrients III)Importance of the Type of Nutrient IV)Size and Export V)Food Web."— Presentation transcript:
The Marine Food Webs 1)What regulates a planktonic food web? I)Light II)Nutrients III)Importance of the Type of Nutrient IV)Size and Export V)Food Web Structure 2)Examples of what controls a food web I)El Nino II)Iron Ex Oscar Schofield (email@example.com)
I) Light Z (meters) Irradiance Intensity Lambert Beers Law Ed 2 = Ed 1 e - z*Kd Ed 2 Ed 1 z1z1 z2z2 zz 1)Because of Lambert Beers Law the ocean is dim 2)Plant life is dependent on light 3) The 1% light level for the majority of the is 100 m or less?
μ mol photons (m -2 s -1 ) Depth (m) Calendar Day μ mol photons m -2 s -1 500 1000 1500 2000 0 Calendar Day Oliver et al. JGR 2004
0 2 4 6 8 10 0.11101001000 Irradiance ( mol photons m -2 s -1 ) Productivity (mg C mg Chl a -2 h -1 ) P max I k = P max / Respiration
Irradiance Intensity Temperature time PP Ed Irradiance Intensity Temperature Z (meters)
Z (meters) net primary production net photosynthesis phytoplankton respiration community respiration euphotic zone Critical depth NPP = Rc Note these are integrated over the water column.
Nutrient concentration (can be nitrogen, phosphorus) Nutrient Uptake Vmax Ks NO 3 Austin Powers Fat Bastard Model System, eats fast when a lot available, but sloppy & alot ends on his shirt not in his belly Miss Manner Model System, eats slow and efficiently, everything ends up in her belly
Nutrient Uptake Varies with Phytoplankton Species
Different Strategies of Nutrient Utilization Diatoms High Vm High Ks Coccolithophores Low Vm Low Ks High or fluctuating nutrients High mixing, upwelling Low average irradiance, light fluctuations High turbulence Chronically oligotrophic Stratified conditions High average irradiance Low turbulence
Size Nutrients are lowNutrients are high n = 6695 Remember small cells, higher surface to volume ratio
Various phytoplankton concentrations of earth's oceans. Purple and blue areas - unproductive regions (open ocean areas) Red and orange areas - productive regions (coastal areas, small basin)
180 o W 135 o W 90 o W 45 o W 0 45 o E 90 o E 135 o E 180 o E 90 o N 60 o N 30 o N 0 o 30 o S 60 o S 90 o S More recently satellite algorithms have been developed for some phytoplankton taxa detection Iglesias-Rodriguez et al. 2000
Surface chlorophyll from CZCS Vertical distribution of Chl from 21,000 profiles Mixed layer depth from NOAA-NODC archive Surface nutrients Brunt-Vaisala 57 provinces on the basis of: Longhurst 1995
Hey look! Here comes a Diatom! Diatom Snow Formation While photosynthesizing DOM is exuded These molecules encounter one another in the aqueous environment Through cation binding the molecules come together forming larger particles The particles are extremely “sticky” and easily adhere to each other as well as other particles in the water
So lets do an experiment: What limits productivity in a high nitrogen/phosphorus ocean? Is it iron limited? Go to a HNLC Ocean (Antarctic), going means sending a graduate student, dump iron in the ocean and watch the phytoplankton respond.
Iron PatchHealth Red = Healthy Blue = Not happy