Current LectureEcosystemsPhysical laws govern energy flow and chemical cycling in ecosystemsConservation of EnergyConservation of MassEnergy, Mass, and Trophic LevelsEnergy and nutrients pass from primary producers (autotrophs) to primary consumers (herbivores) to secondary consumers (carnivores) to tertiary consumers (carnivores that feed on other carnivores)Energy and other limiting factors control primary production in ecosystemsThe extent of photosynthetic production sets the spending limit for an ecosystem’s energy budgetGross and Net Primary ProductionPrimary Production in Aquatic EcosystemsIn marine and freshwater ecosystems, both light and nutrients control primary productionDepth of light penetration affects primary production in the photic zone of an ocean or lakePrimary Production in Terrestrial EcosystemsIn terrestrial ecosystems, temperature and moisture affect primary production on a large scaleNutrient Limitations and Adaptations That Reduce ThemEnergy transfer between trophic levels is typically only 10% efficientProduction efficiency- fraction of energy stored in food that is used for growth, and not respirationProduction Effeciency=net secondary production*100%/assimilation of primary productionTrophic Efficiency and Ecological PyramidsApproximately 0.1% of chemical energy fixed by photosynthesis reaches a tertiary consumerBiological and geochemical processes cycle nutrients and water in ecosystemsBiogeochemical CyclesDecomposition and Nutrient Cycling RatesBio 1150 1st editionLecture 35 Current LectureEcosystems- consists of all the organisms living in a community and the abiotic factors they interact with- dynamics involve two main processes: energy flow and chemical cycling- Energy flows through ecosystems, whereas matter cycles within themPhysical laws govern energy flow and chemical cycling in ecosystemsConservation of Energy- First law of thermodynamics- energy cannot be created or destroyed, only transformed- Energy enters an ecosystem as solar radiation, is conserved, and is lost from organisms as heat- Second law of thermodynamics- every exchange of energy increases the entropy of the universe- In an ecosystem, energy conversions are not completely efficient, and some energy is always lostas heatConservation of Mass- Law of conservation of mass- matter cannot be created or destroyed- Chemical elements are continually recycled within ecosystems- Ecosystems are open systems, absorbing energy and mass and releasing heat and waste productsEnergy, Mass, and Trophic Levels- Energy and nutrients pass from primary producers (autotrophs) to primary consumers (herbivores) to secondary consumers (carnivores) to tertiary consumers (carnivores that feed on other carnivores)- Detritivores (decomposers)- consumers that derive their energy from detritus- Detritus- nonliving organic matter- Prokaryotes and fungi are important detritivores- Decomposition connects all trophic levelsEnergy and other limiting factors control primary production in ecosystems- Primary production- amount of light energy converted to chemical energy by autotrophs during a given time period- In a few ecosystems, chemoautotrophs are the primary producersThe extent of photosynthetic production sets the spending limit for an ecosystem’s energy budgetGross and Net Primary ProductionThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- Gross primary production (GPP)- total primary production - GPP is measured as the conversion of chemical energy from photosynthesis per unit time- Net primary production (NPP)- GPP minus energy used by primary producers for respiration- NPP is expressed as energy per unit area per unit time (J/m2yr), or- Biomass added per unit area per unit time (g/m2yr)- Net ecosystem production (NEP)-total biomass accumulation during a given period- NEP is gross primary production minus the total respiration of all organisms (producers and consumers) in an ecosystem- NEP is estimated by comparing the net flux of CO2 and O2 in an ecosystem, two molecules connected by photosynthesisPrimary Production in Aquatic EcosystemsIn marine and freshwater ecosystems, both light and nutrients control primary productionDepth of light penetration affects primary production in the photic zone of an ocean or lake- More than light, nutrients limit primary production in geographic regions of the ocean and in lakes- A limiting nutrient is the element that must be added for production to increase in an area; oftenN and P- In some areas, sewage runoff has caused eutrophication of lakes, which can lead to loss of most fish species- In lakes, phosphorus limits cyanobacterial growth more often than nitrogenPrimary Production in Terrestrial EcosystemsIn terrestrial ecosystems, temperature and moisture affect primary production on a large scaleNutrient Limitations and Adaptations That Reduce Them- In terrestrial ecosystems, nitrogen is the most common limiting nutrient, but Phosphorus can also be limiting, especially in older soils- Adaptations: mutualisms with bacterial symbionts and mycorrhizae, root hairs, cation exchange systemsEnergy transfer between trophic levels is typically only 10% efficient- Secondary production-amount of chemical energy in food converted to new biomass during a given period of timeProduction efficiency- fraction of energy stored in food that is used for growth, and not respirationProduction Effeciency=net secondary production*100%/assimilation of primary production- Birds and mammals have efficiencies in the range of 13% because of the high cost of endothermy- Fishes have production efficiencies of around 10%- Insects and microorganisms have efficiencies of 40% or moreTrophic Efficiency and Ecological Pyramids- Trophic efficiency- percentage of production transferred from one trophic level to the next- Usually about 10%, with a range of 5% to 20%- Trophic efficiency is multiplied over the length of a food chainApproximately 0.1% of chemical energy fixed by photosynthesis reaches a tertiary consumerCertain aquatic ecosystems have inverted biomass pyramidsInverted biomass pyramids-producers (phytoplankton) are consumed so quickly that they are outweighed by primary consumers- Turnover time - ratio of the standing crop biomass to production- Dynamics of energy flow in ecosystems have important implications for the human population- Eating meat is a relatively