Primary Production Production: Formation of Organic Matter • Autotrophic Organisms (Plants, algae and some bacteria) – Photosynthesis – Chemosynthesis CO2 + 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, Proteins P Energy Transport, DNA, RNA Fe Photosynthetic electron chain …. Nutrients • Macronutrients: N, P, Si, S, Mg, K… • Micronutrients: Cu, Fe, Se… Redfield Ratios: P SW 1 Phytopl. 1 N 15 16 C 1000 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 Phytoplankton Phytoplankton: 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 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 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 HabitatsPhotic 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 www.iku.sintef.no