Topic 2.3: Energy Productivity

Productivity Thursday 11/15 Do Now: Please take out your lab from yesterday. Be ready to share your Rf values for each pigment.

Energy Processes Photosynthesis (Green Plants) sunlight +water + carbon dioxide  oxygen + sugars Respiration (All living things) oxygen + sugars  ATP +water + carbon dioxide ATP is molecular energy storage

Producers Make their own food - photoautotrophs, chemoautotrophs Convert inorganic materials into organic compounds Transform energy into a form usable by living organisms

Photosynthesis Inputs – sunlight, carbon dioxide, water Outputs – sugars, oxygen Transformations – radiant energy into chemical energy, inorganic carbon into organic carbon

Respiration Inputs - sugars, oxygen Outputs - ATP, carbon dioxide, water Transformations – chemical energy in carbon compounds into chemical energy as ATP, organic carbon compounds into inorganic carbon compounds

Definitions gross productivity – total biomass produced net productivity – total biomass produced minus amount used by organism primary productivity – productivity at 1st trophic level secondary productivity – productivity at higher trophic level gross primary productivity – rate at which producers use photosynthesis to make more biomass net primary productivity – rate at which energy for use by consumers is stored in new biomass

Distribution of World Productivity

Gross Productivity Varies across the surface of the earth Generally greatest productivity In shallow waters near continents Along coral reefs – abundant light, heat, nutrients Where upwelling currents bring nitrogen & phosphorous to the surface Generally lowest In deserts & arid regions with lack of water but high temperatures Open ocean lacking nutrients and sun only near the surface

Net Productivity Some of GPP used to stay alive, grow and reproduce NPP is what’s left Most NPP Estuaries, swamps, tropical rainforests Least NPP Open ocean, tundra, desert Open ocean has low NPP but its large area gives it more NPP total than anywhere else

Productivity Calculations Total Primary Production = Gross Primary Production (GPP)  Amount of light energy converted into chemical energy by photosynthesis per unit time Joules / Meter2 / year Net Primary Production  GPP – R, or GPP – some energy used for cell respiration in the primary producers Represents the energy storage available for the whole community of consumers Standing crop = Total living material at a trophic level

More Productivity Calculations Producers: NPP = GPP – R Consumers: GSP = Food eaten – fecal losses NSP = change in mass over time NSP = GSP – R