1Ecology You Already KnowOr Everything I needed to know I learned in 7.014What is Ecology?• Study of interaction between organisms and the environment (Biogeochemistry)• Study of what regulates distribution and abundance of organisms (Population and Community Ecology)View of bioshpere much like the view from inside the cellFunction of EcosystemsStructure of Ecosystems2BIOSPHEREATOMORGANISMPOPULATIONCOMMUNITYECOSYSTEMHierarchical Hierarchical Organization and Organization and EcologyEcologyCELLMOLECULE©©GBRMPA©©GBRMPAPoint of View• Is a human beingA. an organism?B. an ecosystem?C. both A and B?3Antibiotic resistance• Using antibiotics A. causes antibiotic-resistant strains of bacteria to appearB. causes antibiotic-resistant individuals within the population to gain selective advantageC. both A and BAntibiotic acts as a selective agent in the ecosystem of a patient’s organismChanging Ecosystems• New Zealand mud snail (NZMS) has invaded the Western US – outcompeting native snail species in a number of bodies of water. – In some places, NZMS is responsible for up to 60% of the secondary production of the ecosystem. • In New Zealand itself, there is no problem with NZMS. •WHY?4Changing Ecosystems II• Nile Perch was introduced into lake Victoria in mid-1980s – outcompeting and preying on native fish species – popular export • Major factories and fisheries• Local fishermen out of business• Locals too poor to buy this fish• Tilapia is local favorite. Making a comeback.•WHY? Community Structure and Biogeochemistry• Changing community structure changes– Organism balance– Nutrient balance– Community structure• Back to structure-function relationship5Hubbard Brook Experimental Forest, New HampshireChoose two similar watersheds.Document nutrient levels in soil organic matter, plants, and streams.Figure 51.10a upperFigure 51.10a lowerClearcutControlDevegetate one watershed and leave the other intact.Monitor the amount of dissolved substances in streams.6DevegetatedNet dissolved substance (kg/ha)1965–66 1966–67 1967–68 1968–69 1969–70Control10008006004002000YearFigure 51.10bNutrient runoff resultsNO3-K+ , Ca+The Global Water CycleIce 33,000,000Soil Waters 122,000Groundwater 15,300,000Atmosphere 13,000Oceans 1,350,000,000111,00071,000River flow40,00040,000385,000 425,000Net transport to landReference: Schlesinger, 1997Pools (km3)Fluxes (km3/yr)=MRT=pool size/fluxIn ocean: 1,350,000,000/425,000=3,000years7Glucose“CH2O”CO2Reduced CompoundsOxidized CompoundsOxic Oxic ConditionsConditionsAnoxicAnoxicConditionsConditionsH2SSO4NH4+H2SSO4–NO3–H2OO2PhotosynthesisAerobic respirationChemosynthesisAnaerobic respirationBacterial photosynthesisSolar Energy BudgetSolar Energy BudgetTotal From Sun 100%(1.3 x 1021kcal per year)Reflected 30%Absorbed (heat) 47%Used in Evaporation 23%Used in Winds & Currents 0.2%Used in Photosynthesis 0.002%Used to Drive the CyclesSolar RadiationUV radiationAbsorbed by ozoneAbsorbed by earthVisible lightReflected by atmosphereRadiated by atmosphere as heatGreenhouse effectEnergy In = Energy OutSource of energy to most ecosystems on Earth is Solar RadiationHeat radiated by earth843210Formation of Earth4.5 billion years agoChemical evolutionPhotochemical synthesisEukaryotesEubacteriaArchaebacteriaProkaryotesOxygenic phototrophs(cyanobacteria)Development ofozone shieldModern eukaryotesMetazoansDinosaursCarbon burialToday: Release offossil carbon00.1%01%10%20%21%% O2inatmosphereBillions of years before presentMarineoriginBanded ironformationsTerrestrial originRed bedsOrigin of life –3.8 billion years agoAnoxygenicphototrophs(photosyntheticbacteria)Adapted from Brock and Madigan, Biology of MicroorganismsCO2+ H2O “CH2O” + O2↑Burning fossil fuelThe Global Carbon CycleBurial 0.1Ocean 40,00092 90Atmospheric Pool 750 Measured annual increase +3.5Soils 1500Net destruction of vegetation1.510250GPPR50Rivers 1Land plants 560Pools (1015g C)Fluxes (1015g C/yr)See Freeman, Figure 51.1R+2 in vegetation+2 in ocean6+3.5 increase in atm+7.5 anthropogenic sourcesAtmospheric increase is small. Why are we worried?9COCO2 2 Concentration in Atmosphere (parts per million)Concentration in Atmosphere (parts per million)YearYearP>RP>RR >PR >PEmergent PropertyEmergent PropertyIndustrial N fixation 100140biologicalfixation200denitrificationSOILATMOSPHEREOCEANS15biologicalfixation110denitrification1200internal cycling8000internal cycling10burial36river flowgroundwaterThe Global Nitrogen CycleGigatons yr-1<3fixation bylightening1 1 GtGt““gigatongigaton””= 10= 1099tonton= 10= 101515gg= 1 billion = 1 billion10Global Nitrogen- TransformationsReducedReducedOxidizedOxidizedAnoxicAnoxicOxicOxicOrganic - N NH4+NO2-NO3-N2 (gas)N2O (gas)NO (gas)AmmonificationNitrogen FixationDenitrification (anaerobic respiration)Nitrification(chemosynthesis)AssimilatoryNitrate ReductionReleases EnergyRequires EnergyRequires EnergyIndustrial N fixation 100140biologicalfixation200denitrificationSOILATMOSPHEREOCEANS15biologicalfixation140denitification1200internal cycling8000internal cycling?burial?river flow<3fixation bylighteninggroundwaterNitrogen “Cycle” Without Microbes11The Global Nitrogen CycleN-fixation in lightening <3Land plants 3,5001200Soil organic – N 12,000Industrial N-fixation80InternalcyclingGroundwaterRiverflow368000InternalcyclingOceans 570,000Permanent Burial 10Atmosphere 4x109Biological Fixation 140Denitrification<200Denitrification110Fluxes (1012g N/yr)Pools (1012g N)Reference: Schlesinger, 1997Fertilized crops20Cultivated legumes40Denitrification > N-fixation!N2O– sleeping giant of global warmingCoastal UpwellingGlobal Ocean CirculationWest Wind DriftContinents Deflect Ocean CurrentEquatorial Upwelling12Coastal UpwellingGlobal Ocean CirculationWest Wind DriftContinents Deflect Ocean CurrentEquatorial UpwellingPrevailingEl NinoOceanic Conveyer BeltZones of UpwellingZones of UpwellingZones of UpwellingZones of UpwellingDeep Ocean Currents CurrentShallow CurrentsShallow CurrentsWater sinks inN. Atlantic13Burning fossil fuelThe Global Carbon CycleBurial 0.1Ocean 40,00092 90Atmospheric Pool 750 Measured annual increase +3.5Soils 1500Net destruction of vegetation1.510250GPPR50Rivers 1Land plants 560Pools (1015g C)Fluxes (1015g C/yr)See Freeman, Figure 51.1R+2 in vegetation+2 in ocean6+3.5 increase in atm+7.5 anthropogenic sourcesAtmospheric increase is small. Why are we worried?14courtesy of NASALow
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