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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