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EcosystemsEcosystems
Ecosystem Ecosystem
An association of organisms and their An association of organisms and their
physical environment, interconnected physical environment, interconnected
by ongoing flow of energy and a by ongoing flow of energy and a
cycling of materialscycling of materials
Modes of NutritionModes of Nutrition
AutotrophsAutotrophs Capture sunlight or chemical energyCapture sunlight or chemical energy
ProducersProducers
HeterotrophsHeterotrophs Extract energy from other organisms or Extract energy from other organisms or
organic wastesorganic wastes
Consumers, decomposers, detritivoresConsumers, decomposers, detritivores
Simple Simple EcosysteEcosystem Modelm Model
energy input from sun
nutrientcycling
PHOTOAUTOTROPHS(plants, other producers)
HETEROTROPHS(consumers, decomposers)
energy output (mainly heat)
Consumers Consumers
Herbivores Herbivores
Carnivores Carnivores
ParasitesParasites
Omnivores Omnivores
DecomposersDecomposers
Detritivores Detritivores
SPRING
rodents, rabbits
fruits
insects
birds
SUMMER
rodents, rabbits
fruits
insects
birds
Seasonal variation in the diet of an omnivore (red fox)
Trophic LevelsTrophic Levels
All the organisms at a trophic level are All the organisms at a trophic level are
the same number of steps away from the the same number of steps away from the
energy input into the systemenergy input into the system
Producers are closest to the energy input Producers are closest to the energy input
and are the first trophic leveland are the first trophic level
Trophic Levels in Trophic Levels in PrairiePrairie
5th
4th
3rd
2nd
1st
Fourth-level consumers (heterotrophs):
Top carnivores, parasites, detritivores, decomposers
Third-level consumers (heterotrophs):Carnivores, parasites, detritivores, decomposers
Second-level consumers (heterotrophs):
Carnivores, parasites, detritivores, decomposers
First-level consumers (heterotrophs):
Herbivores, parasites, detritivores, decomposers
Primary producers (autotrophs):
Photoautotrophs, chemoautotrophs
Food ChainFood Chain
A straight line A straight line
sequence of who sequence of who
eats whom eats whom
Simple food chains Simple food chains
are rare in natureare rare in nature
MARSH HAWK
UPLAND SANDPIPER
GARTER SNAKE
CUTWORM
FoodFoodWebWeb
Energy Losses Energy Losses
Energy transfers are never 100 percent Energy transfers are never 100 percent
efficientefficient
Some energy is lost at each stepSome energy is lost at each step
Limits the number of trophic levels in an Limits the number of trophic levels in an
ecosystem ecosystem
Two Types of Food WebsTwo Types of Food Webs
Producers (photosynthesizers)
Producers (photosynthesizers)
herbivores
carnivores
decomposers
decomposers
detritivores
ENERGY OUTPUT ENERGY OUTPUT
Grazing Food Web Detrital Food Web
Biological MagnificationBiological Magnification
A nondegradable or slowly degradable A nondegradable or slowly degradable
substance becomes more and more substance becomes more and more
concentrated in the tissues of concentrated in the tissues of
organisms at higher trophic levels of a organisms at higher trophic levels of a
food webfood web
DDT in Food WebsDDT in Food Webs
Synthetic pesticide Synthetic pesticide banned in the United banned in the United States since the 1970sStates since the 1970s
Birds that were top Birds that were top carnivores accumulated carnivores accumulated DDT in their tissuesDDT in their tissues
BioaccumulationBioaccumulation
Primary ProductivityPrimary Productivity
GrossGross primary productivity is ecosystem’s primary productivity is ecosystem’s
total rate of photosynthesistotal rate of photosynthesis
NetNet primary productivity is rate at which primary productivity is rate at which
producers store energy in tissues in producers store energy in tissues in
excess of their aerobic respirationexcess of their aerobic respiration
Primary Productivity Primary Productivity VariesVaries
Seasonal variationSeasonal variation
Variation by habitatVariation by habitat
The harsher the environment, the The harsher the environment, the
slower plant growth, the lower the slower plant growth, the lower the
primary productivity primary productivity
Silver Springs StudySilver Springs Study
Aquatic ecosystem in FloridaAquatic ecosystem in Florida Site of a long-term study of a grazing food webSite of a long-term study of a grazing food web
5
decomposers, detritivores(bacteria, crayfish)
1.5
1.1
37
third-level carnivores(gar, large-mouth bass)
second-level consumers(fishes, invertebrates)
first-level consumers(herbivorous fishes,turtles, invertebrates)
809 primary producers (algae,eelgrass, rooted plants)
Biomass pyramid
Pyramid of Energy FlowPyramid of Energy Flow
Primary producers trapped about 1.2 Primary producers trapped about 1.2 percent of the solar energy that entered the percent of the solar energy that entered the ecosystemecosystem
6-16% passed on to next level6-16% passed on to next level
detritivores
21
383
3,368
20,810 kilocalories/square meter/year
top carnivores
carnivores
herbivores
producers
decomposers
All Heat in the EndAll Heat in the End
At each trophic level, the bulk of the At each trophic level, the bulk of the energy received from the previous level energy received from the previous level is used in metabolismis used in metabolism
This energy is released as heat energy This energy is released as heat energy and lost to the ecosystemand lost to the ecosystem
Eventually, all energy is released as heatEventually, all energy is released as heat
Biogeochemical CycleBiogeochemical Cycle
The flow of a nutrient from the The flow of a nutrient from the
environment to living organisms and environment to living organisms and
back to the environmentback to the environment
Main reservoir for the nutrient is in the Main reservoir for the nutrient is in the
environmentenvironment
Three CategoriesThree Categories
Hydrologic cycleHydrologic cycle
WaterWater
Atmospheric cycles Atmospheric cycles
Nitrogen and carbonNitrogen and carbon
Sedimentary cycles Sedimentary cycles
Phosphorus and sulfurPhosphorus and sulfur
Hydrologic CycleHydrologic Cycle
evaporation from ocean
425,000
precipitation into ocean 385,000
evaporation from land plants
(evapotranspiration) 71,000
precipitation onto land 111,000
wind driven water vapor40,000
surface and groundwater flow
40,000
Atmosphere
Oceans Land
Hubbard Brook Hubbard Brook ExperimentExperiment
A watershed was experimentally stripped A watershed was experimentally stripped
of vegetationof vegetation
All surface water draining from watershed All surface water draining from watershed
was measuredwas measured
Removal of vegetation caused a six-fold Removal of vegetation caused a six-fold
increase in the calcium content of the increase in the calcium content of the
runoff waterrunoff water
Hubbard Brook Hubbard Brook ExperimentExperiment
losses fromdisturbed watershed
time ofdeforestation
losses fromundisturbed watershed
Phosphorus CyclePhosphorus Cycle
Phosphorus is part of phospholipids and Phosphorus is part of phospholipids and
all nucleotidesall nucleotides
It is the most prevalent limiting factor in It is the most prevalent limiting factor in
ecosystems ecosystems
Main reservoir is Earth’s crust; no Main reservoir is Earth’s crust; no
gaseous phasegaseous phase
Phosphorus CyclePhosphorus Cycle
GUANO
FERTILIZER
ROCKS
LAND FOOD WEBS
DISSOLVED IN OCEAN
WATER
MARINE FOOD WEBS
MARINE SEDIMENTS
excretion
weathering
mining
agriculture
uptake by autotrophs
death, decomposition
sedimentation setting out leaching, runoff
weathering
uplifting over geolgic time
DISSOLVED IN SOILWATER,
LAKES, RIVERS
uptake by autotrophs
death, decomposition
Human EffectsHuman Effects
In tropical countries, clearing lands for In tropical countries, clearing lands for
agriculture may deplete phosphorus-agriculture may deplete phosphorus-
poor soilspoor soils
In developed countries, phosphorus In developed countries, phosphorus
runoff is causing eutrophication of runoff is causing eutrophication of
waterwayswaterways
Carbon CycleCarbon Cycle
Carbon moves through the atmosphere Carbon moves through the atmosphere
and food webs on its way to and from and food webs on its way to and from
the ocean, sediments, and rocksthe ocean, sediments, and rocks
Sediments and rocks are the main Sediments and rocks are the main
reservoirreservoir
Carbon CycleCarbon Cycle
photosynthesisTERRESTRIAL
ROCKS
volcanic action
weathering
diffusion
Bicarbonate, carbonate
Marine food webs
Marine Sediments
Atmosphere
TerrestrialRocks
Soil WaterPeat, Fossil
Fuels
Land Food Webs
Carbon in the OceansCarbon in the Oceans
Most carbon in the ocean is dissolved Most carbon in the ocean is dissolved carbonate and bicarbonatecarbonate and bicarbonate
Ocean currents carry dissolved carbon Ocean currents carry dissolved carbon
Carbon in AtmosphereCarbon in Atmosphere
Atmospheric carbon is mainly carbon Atmospheric carbon is mainly carbon dioxidedioxide
Carbon dioxide is added to atmosphereCarbon dioxide is added to atmosphere Aerobic respiration, volcanic action, Aerobic respiration, volcanic action,
burning fossil fuels burning fossil fuels
Removed by photosynthesisRemoved by photosynthesis
Greenhouse EffectGreenhouse Effect
Greenhouse gases impede the escape Greenhouse gases impede the escape
of heat from Earth’s surfaceof heat from Earth’s surface
Global WarmingGlobal Warming
Long-term increase in the temperature Long-term increase in the temperature
of Earth’s lower atmosphereof Earth’s lower atmosphere
Carbon Dioxide IncreaseCarbon Dioxide Increase
Carbon dioxide levels fluctuate Carbon dioxide levels fluctuate
seasonally seasonally
The average level is steadily increasingThe average level is steadily increasing
Burning of fossil fuels and deforestation Burning of fossil fuels and deforestation
are contributing to the increaseare contributing to the increase
Other Greenhouse GasesOther Greenhouse Gases
CFCs - synthetic gases used in plastics CFCs - synthetic gases used in plastics
and in refrigerationand in refrigeration
Methane - produced by termites and Methane - produced by termites and
bacteria and cow burpsbacteria and cow burps
Nitrous oxide - released by bacteria, Nitrous oxide - released by bacteria,
fertilizers, and animal wastesfertilizers, and animal wastes
Store Liquid COStore Liquid CO22 on on Ocean Bottom?Ocean Bottom?
““At shallow depths liquid carbon dioxide will At shallow depths liquid carbon dioxide will rise to the surface. But based on laboratory rise to the surface. But based on laboratory experiments with carbon dioxide hydrates, experiments with carbon dioxide hydrates, researchers imagined that liquid carbon researchers imagined that liquid carbon dioxide put deep in the ocean would form a dioxide put deep in the ocean would form a stable layer on the seafloor with a skin of stable layer on the seafloor with a skin of solid hydrate as a boundary, like a pond solid hydrate as a boundary, like a pond covered by ice in winter.” from the Monterey covered by ice in winter.” from the Monterey Bay Aquarium Research InstituteBay Aquarium Research Institute
http://www.cnn.com/NATURE/9905/10/oceans.enn/
Nitrogen CycleNitrogen Cycle
Nitrogen is used in amino acids and Nitrogen is used in amino acids and
nucleic acidsnucleic acids
Main reservoir is nitrogen gas in the Main reservoir is nitrogen gas in the
atmosphereatmosphere
Nitrogen CycleNitrogen Cycle
NO3-
IN SOIL
NITROGEN FIXATION
by industry for agriculture
FERTILIZERS
FOOD WEBS ON LAND
NH3-, NH4
+
IN SOIL
1. NITRIFICATION
loss by leaching
uptake by autotrophs
excretion, death,
decomposition
uptake by autotrophs
NITROGEN FIXATION
loss by leaching
AMMONIFICATION
2. NITRIFICATION
NITROGENOUS WASTES, REMAINS IN SOIL
GASEOUS NITROGEN (N2)
IN ATMOSPHERE
NO2-
IN SOIL
Nitrogen FixationNitrogen Fixation
Plants cannot use nitrogen gasPlants cannot use nitrogen gas
Nitrogen-fixing bacteria convert Nitrogen-fixing bacteria convert
nitrogen gas into ammonia (NHnitrogen gas into ammonia (NH33))
Ammonia and ammonium can be Ammonia and ammonium can be
taken up by plantstaken up by plants
DiazotrophsDiazotrophs
Soil bacteria that fix nitrogenSoil bacteria that fix nitrogen Most famous: Most famous: RhizobiaRhizobia Rhizobia lives in a symbiotic relationship Rhizobia lives in a symbiotic relationship
with legumeswith legumes
Nitrogen Fixation videoNitrogen Fixation video
http://www.youtube.com/watch?v=k3TrdF-PWNg
NHNH44 ++ to NO to NO33 - Nitrofication- Nitrofication
““NitrificationNitrification is the biological oxidation is the biological oxidation of ammonia with oxygen into nitriteof ammonia with oxygen into nitrite
Followed by the oxidation of these nitrites Followed by the oxidation of these nitrites into nitratesinto nitrates
Nitrification is an important step in the Nitrification is an important step in the nitrogen cycle in soil “nitrogen cycle in soil “
Important bacteria: Important bacteria: NitrosomonasNitrosomonas and and NitrobacterNitrobacter http://en.wikipedia.org/wiki/Nitrification
Sea Battle South AmericaSea Battle South America
Ammonification & Ammonification & NitrificationNitrification
Bacteria and fungi carry out Bacteria and fungi carry out
ammonification, conversion of ammonification, conversion of
nitrogenous wastes to ammonianitrogenous wastes to ammonia
Nitrifying bacteria convert ammonium to Nitrifying bacteria convert ammonium to
nitrites and nitratesnitrites and nitrates
Nitrogen LossNitrogen Loss
Nitrogen is often a limiting factor in ecosystemsNitrogen is often a limiting factor in ecosystems
Nitrogen is lost from soils via leaching and Nitrogen is lost from soils via leaching and
runoff runoff
Denitrifying bacteria convert nitrates and Denitrifying bacteria convert nitrates and
nitrites to nitrogen gas (often occurs in water nitrites to nitrogen gas (often occurs in water
logged soil)logged soil)
Human EffectsHuman Effects
Humans increase rate of nitrogen loss by Humans increase rate of nitrogen loss by clearing forests and grasslandsclearing forests and grasslands
Humans increase nitrogen in water and Humans increase nitrogen in water and air by using fertilizers and by burning air by using fertilizers and by burning fossil fuelsfossil fuels
Too much or too little nitrogen can Too much or too little nitrogen can compromise plant healthcompromise plant health
Sewage spill hits Peachtree Sewage spill hits Peachtree Creek, Chattahoochee Creek, Chattahoochee
Over a million gallonsOver a million gallons of raw sewage poured into of raw sewage poured into a creek Monday just upstream of the Chattahoochee a creek Monday just upstream of the Chattahoochee River and near the spot where Atlanta draws its River and near the spot where Atlanta draws its drinking water.drinking water.
Before a collapsed 36-inch sewer pipe was repaired, Before a collapsed 36-inch sewer pipe was repaired, sewage flowed into Peachtree Creek at the rate of sewage flowed into Peachtree Creek at the rate of 10,000 gallons a minute for two hours, said Janet 10,000 gallons a minute for two hours, said Janet Ward, a spokeswoman for Atlanta's Watershed Ward, a spokeswoman for Atlanta's Watershed Management Department. Management Department. The incident occurred The incident occurred near the Chattahoochee Water Treatment near the Chattahoochee Water Treatment Plant off Bolton Road, where the city gets Plant off Bolton Road, where the city gets drinking water.drinking water.
The Atlanta Journal-ConstitutionPublished on: 11/29/05
Dead WatersDead Waters Massive oxygen-starved zones are Massive oxygen-starved zones are
developing along the world's coastsdeveloping along the world's coasts
““Summer tourists cruising the waters Summer tourists cruising the waters off Louisiana or Texas in the Gulf of off Louisiana or Texas in the Gulf of Mexico take in gorgeous vistas as Mexico take in gorgeous vistas as they pull in red snappers and blue they pull in red snappers and blue marlins. Few realize that the lower half marlins. Few realize that the lower half of the water column below them may of the water column below them may lack fish, despite the piscine bounty lack fish, despite the piscine bounty near the surface.”near the surface.”
Nitrates and Phosphates Nitrates and Phosphates Contributions from Contributions from FertilizersFertilizers
““Typically, they appear where a river Typically, they appear where a river spews rich plumes of nutrients into water spews rich plumes of nutrients into water that's stratified because of either that's stratified because of either temperature or salinity differences temperature or salinity differences between the bottom and the top of the between the bottom and the top of the water column. If the water doesn't mix, water column. If the water doesn't mix, oxygen isn't replenished in the lower oxygen isn't replenished in the lower half.” half.”
Eutrophication Leads to Eutrophication Leads to Oxygen DepletionOxygen Depletion
Bacteria Use Up Most of Bacteria Use Up Most of the Othe O22
““the Mississippi River deposits water that is the Mississippi River deposits water that is heavily enriched with plant nutrients, principally heavily enriched with plant nutrients, principally nitrate. This pollutant fertilizes the abundant nitrate. This pollutant fertilizes the abundant growth of tiny, floating algae. As blooms of the growth of tiny, floating algae. As blooms of the algae go through their natural life cycles and algae go through their natural life cycles and die, they fall to the bottom and create a feast die, they fall to the bottom and create a feast for bacteria. Growing in unnatural abundance, for bacteria. Growing in unnatural abundance, the bacteria use up most of the oxygen from the bacteria use up most of the oxygen from the bottom water.” the bottom water.”
http://www.sciencenews.org/articles/20040605/bob9.asp
Black SeaBlack Sea