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

autotrophsautotrophs omnivoresomnivores carnivorescarnivores

Pyramimonas parkeae Dunaliella tertiolecta Gephyrocapsa oceanica Ceratium sp. Thoracosphaera heimii Ditylum brightwellii Diatom sp.

I) Light Z (meters) Irradiance Intensity Lambert Beers Law Ed 2 = Ed 1 e -  z*Kd Ed 2 Ed 1 z1z1 z2z2 zz 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 Calendar Day Oliver et al. JGR 2004

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.

CHL a >3 0 mg m -3 UML Low wind High wind

Irradiance Phytoplankton Physical mixing processes Nutrients

Biomass and Nutrients Sta E ( )

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

Cullen et al. 2003

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

IrradianceZooplankton Higher Trophic Levels Phytoplankton Physical mixing processes Nutrients

GRAZERS in the plankton sea soft-bodies, asexual, consumes all particle sizes, bloom & bust hard-bodies, sexual, consume specific particle size ranges, roving bands

phytoplankton zooplankton fish This assumes a trophic transfer efficiency of 10%

Upwelling zones (2 trophic levels) Phytoplankton  Anchovies (20 % transfer efficiency) Coastal Regions (4 trophic levels) Phytoplankton  herbivorous zooplank.  carnivorous zooplank.  fish (15% efficiency) Open ocean (5 trophic levels) Phytoplankton  herb. Zooplank.  carniv. Zooplank.  carniv. Fish  tuna (10% efficiency)

AreaPlant prod.EfficiencyTrophic levelsEst. fish Open 39* % 54*10 6 Ocean Coastal 8.6* % 429*10 6 Ocean upwelling 0.23* % 246*10 6 (metric tons per year) (metric tons carbon per year)

Irradiance Sinkage & Senescence Sinkage & Senescence Particle Dynamics Particle Flux (Carbon flux) Zooplankton Higher Trophic Levels Phytoplankton Physical mixing processes Nutrients

Sequestration of Atmospheric Carbon Chisholm, 2000

MARINE SNOW What is it? How is formed? (particle-particle, sticky, virus) Why is it important?

What is Marine Snow?

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

Marine snow particles from off New Jersey

Irradiance Elemental Flux CO2 N2 Fe Carbon N2Fe rivers Wind Continental shelf Continental slope S Mixing processes New Nutrients Phytoplankton Sinkage & Senescence Particle Dynamics Zooplankton Higher Trophic Levels Mixed Layer Depth Regenerated Nutrients Water column depth Mixed Layer Depth

A Natural Experiment: Are nutrients from the deep ocean driving the primary productivity? El Nino

Top: “normal” forcing condition Bottom: El Niño forcing condition Open University, 1998 Normal El Nino

Top: normal Bottom: El Niño condition Open University, 1998 Normal El Nino

JPL El Nino La Nina Note coastal effect

HNLC

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

GLOBAL

Cell size effects the trophic transfer of matter and energy in the food web Cullen et al. (Cullen et al., 2002)

(from N.Gruber) (Takahashi et al 1995) Net CO 2 flux Example: variability in carbon uptake

MARTIN GLACIAL & INTERGLACIAL