Secondary ProductionPowerPoint PresentationSlide 3Slide 4Slide 5Trophic LevelsMeasuring Net ProductionSlide 8Slide 9Slide 10Slide 11Estimates of Energy Flow in a Temperate Deciduous ForestSlide 13HerbivoryLow Ecological EfficiencySlide 16Slide 17Slide 18Slide 19Slide 20Limits to Secondary Primary ProductionSlide 22Secondary Production‘Maintenance’ (or respiration)‘Production’Energy Removed From Lower Trophic LevelEnergy Not UsedGross Energy IntakeDigested Energy Egested Energy Assimilated Energy Urinary Waste Resting Energy Activity Growth ReproductionC = (Mr + Ma + SDA) + (F + U) + (Gs + Gr)Metabolism Waste GrowthC = rate of energy consumptionMr = standard metabolic rate (resting energy)Ma = metabolic rate increase due to activity (above Mr)SDA = metabolic rate increase due to specific dynamic action (digestion)F + U = waste losses due to egestion (feces) and excretion (urine) ratesGs = somatic growth rate due to protein synthesis and lipid depositionGr = growth rate due to gonad (reproductive) synthesisEnergy BudgetMaintenance Net ProductionEnergy partitioning is not equal among species and can change depending on season.Larger animals require more energyMammals and birds (warm blooded) need more than reptiles (cold blooded)Herbivorous mammals: Log (FMR) = 0.774 + 0.727(log body mass)Trophic LevelsHeat Heat Heat HeatHeatHeatHeatFirst TrophicLevelSecond TrophicLevelThird TrophicLevelFourth TrophicLevelSolarenergyProducers(plants)Primaryconsumers(herbivores)Tertiaryconsumers(top carnivores)Secondaryconsumers(carnivores)Detritvores(decomposers and detritus feeders)Measuring Net Production•Production = +•Need to estimate change in biomass, natality (birth rate), and loss due to death (including harvesting) or emigrationnet change in biomasslosses by mortalityProduction Efficiency =Net Productivity of species nAssimilation of species nGroup Production EfficiencyRespirationMammals and birds 1 – 3% 97 – 99%Insects 10 – 41% 59 – 90%Why the difference?  Homeothermy (it takes a lot of energy to keep warm)Trophic Efficiency =Net Production at trophic level i + 1Net production at trophic level i05101520253035402 6 10 14 16 20 24Transfer Efficiency (%)No. of CasesEnergy not transferred is lost as respiration or to detritus.For aquatic systems, average ~ 10.How much primary production is required to support a particular fishery?Tuna are top predators operating at trophic level 4. In 1990 2,975,000 tons of tuna were taken. This is equivalent to 0.1 g carbon per m2 of open ocean per year!!!! How much production is needed to sustain this fishery assuming a 10% transfer efficiency?Tuna 0.1Pelagic Fishes 1.0Zooplankton 10 Phytoplankton 100Need 1.0 g pelagic fish, 10 grams zooplankton, and 100 grams of phytoplankton per m2/year of open ocean to support this fishery – and this is just harvested tuna!!!!!When all of the data for worldwide fisheries are aggregated, on average 8% of global aquatic primary production is being used to produce the global fisheries catch. But, production varies with ecosystem type:Ecosystem TypeArea (106km2)NPP (gCm-2yr-1)Fishery Catch (gCm-2yr-1)P. Production required (%)Open Ocean 332.0 103 0.012 1.8Upwellings 0.8 973 25.560 25.1Tropical Shelves 8.6 310 2.871 24.2Temperate Shelves 18.4 310 2.306 35.3Coastal/reef systems 2.0 890 10.510 8.3Rivers and Lakes 2.0 290 4.3 23.6Weighted Means 126 0.330 8.0Estimates of Energy Flow in a Temperate Deciduous ForestAquatic ecosystem herbivores consume a higher fraction of the primary production than in terrestrial ecosystems (red arrows = average)HerbivoryEcosystem NPP going to consumption (%)Tropical rain forest 7Temperate deciduous forest 5Grassland 10Open ocean 40Oceanic upwelling zones 35Reduction in standing crop of vascular plants from herbivoresTerrestrial ecosytems 26%Marine ecosystems 65%Freshwater ecosystems 31%Low Ecological Efficiency •Organisms at the base of the food web are much more abundant than those near the top•Eltonian pyramid – a diagram demonstrating the number, biomass, or energy distributions across size classesHeatHeatHeatHeatHeat10101001001,0001,00010,00010,000Usable energyUsable energyAvailable atAvailable atEach tropic levelEach tropic level(in kilocalories)(in kilocalories)ProducersProducers(phytoplankton)(phytoplankton)Primaryconsumers(zooplankton)Secondaryconsumers(perch)Tertiaryconsumers(human)DecomposersBiomassWhy does the ocean have such a low biomass of primary producers?•Phytoplankton such as diatoms reproduce by dividing and can divide every few hours.–Because of their fast population growth rate, they are able to support a large number of primary consumers.•Plants are the primary producers in an abandoned field.–Have a much longer lifespan than phytoplankton•Need a much larger biomass of plants to support the primary consumers.Number of OrganismsWhy does a temperate forest have so few individual primary producers compared to a grassland?•In a temperate forest, a single tree can support many primary consumers because of its large size.•It takes a lot of individual grasses to = the biomass of a large tree.Number of OrganismsLimits to Secondary Primary Production•Primary production is an obvious limiter–Also include the 2nd law of thermodynamicsAbove ground PP and herbivore biomass•Carrying Capacity – the number or weight of animals of a single or mixed population that can be supported permanently on a given area•Ecological Carrying Capacity – maximum density of animals that can be sustained without inducing negative effects on vegetation•Economic Carrying Capacity – density of animals that enables maximal sustained harvesting and is always lower than the ecological carrying