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Ch. 9. Aquatic ecosystems and Physiology: Energy Flow Productivity Dissolved Oxygen. Fig. 9.1. Hypothetical Trophic Structure Model. Boxes are filled with functional groups, measured as calories of energy, or moles of chemicals, biomass, or numbers.
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Ch. 9.Aquatic ecosystems and Physiology:Energy Flow Productivity Dissolved Oxygen Fig. 9.1. Hypothetical Trophic Structure Model. Boxes are filled with functional groups, measured as calories of energy, or moles of chemicals, biomass, or numbers.
Fig 1.14a. Energy flow model of Cedar Bog Lake, Minnesota (Lindeman 1942)
Fig 1.14b. Energy flow model of Silver Springs, Florida (Odum 1971)
PRIMARY PRODUCTIVITY: PHOTOSYNTHESIS NPP = GPP – Respiration Fig. 9.4.
Importance of dissolved oxygen in aquatic systems • Affect the distribution of aerobic heterotrophic life • Impacts the solubility of phosphorus and other nutrients • Influences redox potential (Ch. 16) and thus the solubility of redox-sensitive materials • May be used to estimate ecosystem productivity
CO2 + H2O CH2O + O2 Productivity may be measured in units of mgC volume-1 time-1 Because it takes two moles of O2 to fix 1 mole of C, productivity may also be measured in units of mgO2 volume-1 time-1 Ratio of moles of C to moles of oxygen = 12/32 = 0.375; i.o.w. 1 mg O2 produced = 0.375 mg C fixed Examples of productivity measurement techniques: Light - dark bottles Diel cycles in oxygen levels 14C uptake
PN=PG-R R Lingeman and Ruardij, 1981