1. 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.

2. Fig 1.14a. Energy flow model of Cedar Bog Lake, Minnesota (Lindeman 1942)

3. Fig 1.14b. Energy flow model of Silver Springs, Florida (Odum 1971)

4. PRIMARY PRODUCTIVITY: PHOTOSYNTHESIS Fig. 9.4. NPP = GPP – Respiration

5. Horne and Goldman 1994

7. Kalff 2002

8. 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

9. Horne and Goldman 1994

11. Productivity may be measured in units of mgC volume -1 time -1 Because it takes two moles of O 2 to fix 1 mole of C, productivity may also be measured in units of mgO 2 volume -1 time -1 CO 2 + H 2 O CH 2 O + O 2 Ratio of moles of C to moles of oxygen = 12/32 = 0.375; i.o.w. 1 mg O 2 produced = 0.375 mg C fixed Examples of productivity measurement techniques: Light - dark bottles Diel cycles in oxygen levels 14 C uptake

12. Lingeman and Ruardij, 1981 P N =P G -R R

13. Kalff 2002