Primary Production

Production: Formation of Organic Matter

• Autotrophic Organisms(Plants, algae and some bacteria)

– Photosynthesis– ChemosynthesisCO2 + Electron Donor + energy CH2O + other

• Heterotrophic Organisms (most bacteria and animals)

RESPIRATION (Autotrophs & Heterotrophs)

CH2O + O2 CO2 + H2O + Energy (ATP)

Primary Production

Photosynthesis

6CO2 + 6H2O +light C6H12O6 + O2

Need: Co2, H2O, Light and…..

N DNA, RNA, ProteinsP Energy Transport, DNA, RNAFe Photosynthetic electron chain

….

Nutrients

• Macronutrients: N, P, Si, S, Mg, K…• Micronutrients: Cu, Fe, Se…

Redfield Ratios:

P N CSW 1 15 1000Phytopl. 1 16 106

SW and FW Phytoplankton macronutrient limitation

Oceanic Productivity Limiting Factors

• Light• Nutrients

Bristlecone Pine: 4.723 years old!

Kelp Forest

Macroalgae: 3% Ocean Photosynthesis

www.underwaterplanet.com

PhytoplanktonPhytoplankton: 97% Ocean Photosynthesis

Phytoplankton Dominance

• Phytoplankton– Optimize surface area/volume

(4/3Пr2) / (4/3Пr3)

• Smaller size larger surf. area/volume• 5μm = 1/5• 10μm = 1/10

– Small Particles sink slower• Larger surf. area/volume Slower sinking

Phytoplankton spines: increase in surface for higher floatability

Energy – Mass models

Measuring Productivity

• Plant Biomass – How much phytoplankton is there

(mg Chl/m3) or (μg Chl/liter)

• Productivity– A rate of how much carbon is

produced per time• g Carbon / m3 / day

– GROSS Productivity = Carbon fixed through Photosynthesis per time

– NET Productivity = Gross Prod - Respiration

Measuring Productivity

Standing Crop: Plant Biomass

Grass clippings after 1 week: Productivity

What do Chl maps really measure?

Biomass!

Measurement of Productivity: C14 incorporation experiments

Phytoplankton consumption: grazing

So Chl concentration is reasonable estimation of primary productivity in

surface waters

Ecosystem Productivity(Annual net productivity)

Ocean primary productivity

Productivity and depth

Open water(low

productivity)

Coastal and Estuarine waters (high productivity)

Productivity measurements with DEPTH

Photic Zone and Compensation Depth

Upper Pelagic Habitats-

Photic Zone

Vertical distribution of Primary production

• Surface photoinhibition (UV light?)• Photosynthetic Maximum• Compensation depth• Critical Depth

– Refers to the whole population

– Photosynthesistotal = Respirationtotal

Productivity and depth

Critical Depth• CRITICAL DEPTH: Depth at which total

primary productivity = Total respiration

• MIXING DEPTH – Depth above which all water is throughly mixed (WIND)

THE PUNCHLINE:• MIXING DEPTH > CRITICAL DEPTH:

Then Phytopl. are partially swept down and a bloom cannot not occur

• MIXING DEPTH < CRITICAL DEPTH: then a Phytopl. Bloom can occur

CRITICAL DEPTH

Nitrogen Cycle

Phosphorous Cycle

Figure 13.8

Vertical distribution of Nutrients

Atlantic & Pacific nutrient distribution

Atlantic & Pacific oxygen distribution

Nutrients & distance to shore

Phytoplankton and distance to coast

Nutrient upwelling

July Chlorophyll

January Chlorophyll

Latitudinal effects on Primary productivity

Seasonal stratification

Seasonal effects on Primary Productivity

Consumers or Grazers

Temperate Ocean Spring Bloom

Absorption Spectrum

Adapted Algae

PI Curves

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