Transcript Ecosystems - East Tech Titans
Ecosystems
An ecosystem is all of the organisms in an area, along with their nonliving environment Example: aquarium Living + Non-living (Biotic + Abiotic)
Trophic Levels
Organisms in a community are related to each other through feeding relationships Each step up in the transfer of energy is known as a trophic level All energy ultimately comes from the SUN
Trophic Levels
Decomposers/ Detritivores Eat detritus (organic waste/remains of dead organisms) Can fit in to a food chain or web at any location
Trophic Levels
Producers Convert solar (or chemical) energy into organic compounds Primary consumers Eat producers Secondary consumers Eat primary consumers Tertiary consumers Eat secondary consumers
Pyramid of Numbers/Biomass/Ener gy
Numbers, energy, & biomass decreases as one moves up the food chain.
Biomass- dry mass of organic matter
Trophic Levels
Ten-Percent Law Usable energy is lost through each transfer of energy Why? (Remember the law of conservation of energy says energy cannot be created or destroyed; it only changes form.) Only about 10% of the energy at one trophic level is transferred to the next trophic level. 90% is lost as heat with each transfer.
Food Chain
A straight-line sequence of who eats whom Simple food chains are rare in nature marsh hawk upland sandpiper garter snake cutworm plants
Tall-Grass Prairie Food Web
marsh hawk sandpiper crow snake frog weasel badger coyote spider earthworms, insects sparrow vole grasses, composites pocket gopher ground squirrel
Primary Productivity
Primary Productivity: The amount of light energy converted to sugars by autotrophs in an ecosystem Gross vs. Net Primary Productivity GPP: the amount of light energy that is converted to chemical energy by photosynthesis per unit time NPP: GPP minus the energy used by the primary producers for cellular respiration GPP-R=NPP
Limiting Nutrients
What limits primary production?
Aquatic Ecosystems Light (depth penetration) Nitrogen Phosphorus Terrestrial Ecosystems Temperature Moisture Minerals (N & P are the main limiting factors for plants.)
Biogeochemical Cycle
The flow of a nutrient from the environment to living organisms and back to the environment Main reservoir for the nutrient is in the environment
Hydrologic Cycle
Atmosphere
evaporation from ocean 425,000 precipitation into ocean 385,000 wind-driven water vapor 40,000 evaporation from land plants (evapotranspiration) 71,000 precipitation onto land 111,000 surface and groundwater flow 40,000
Ocean Land
Figure 48.14
Page 876
diffusion between atmosphere and ocean combustion of fossil fuels bicarbonate and carbonate in ocean water photosynthesis aerobic respiration marine food webs incorporation into sediments death, sedimentation uplifting marine sediments sedimentation
Carbon Cycle - Marine
Figure 48.16
Page 878
atmosphere volcanic action terrestrial rocks combustion of fossil fuels photosynthesis aerobic respiration combustion of wood weathering land food webs sedimentation soil water leaching, runoff death, burial, compaction over geologic time peat, fossil fuels
Carbon Cycle - Land
Figure 48.16
Page 878
Carbon in Atmosphere
Atmospheric carbon is mainly carbon dioxide Carbon dioxide is added to atmosphere Aerobic respiration, volcanic action, burning fossil fuels Removed by photosynthesis
Greenhouse Effect
Greenhouse gases impede the escape of heat from Earth’s surface Figure 48.18, Page 880
Global Warming
Long-term increase in the temperature of Earth’s lower atmosphere
Figure 48.19, Page 881
Nitrogen Cycle
Nitrogen is used in amino acids and nucleic acids Main reservoir is nitrogen gas in the atmosphere
Nitrogen Cycle
gaseous nitrogen (N 2 ) in atmosphere nitrogen fixation by industry food webs on land fertilizers uptake by autotrophs excretion, death, decomposition uptake by autotrophs nitrogen fixation nitrogenous wastes, remains NO 3 in soil dentrification ammonification 2. Nitrification NH 3 ,NH 4 + in soil leaching 1. Nitrification NO 2 in soil leaching
Figure 48.21
Page 882
Nitrogen Fixation
Plants cannot use nitrogen gas Nitrogen-fixing bacteria convert nitrogen gas into ammonia (NH 3 ) Ammonia and ammonium can be taken up by plants
Ammonification & Nitrification
Bacteria and fungi carry out ammonification conversion of nitrogenous wastes to ammonia Nitrifying bacteria convert ammonium to nitrites and nitrates
Nitrogen Loss
Nitrogen is often a limiting factor in ecosystems Nitrogen is lost from soils via leaching and runoff Denitrifying bacteria convert nitrates and nitrites to nitrogen gas
Phosphorus Cycle
Phosphorus is part of phospholipids and all nucleotides It is the most prevalent limiting factor in ecosystems Main reservoir is Earth’s crust; no gaseous phase
Phosphorus Cycle
mining FERTILIZER excretion uptake by autotrophs GUANO weathering MARINE FOOD WEBS DISSOLVED IN OCEAN WATER death, decomposition sedimentation settling out MARINE SEDIMENTS weathering agriculture uptake by autotrophs DISSOLVED IN SOILWATER, LAKES, RIVERS death, decomposition LAND FOOD WEBS leaching, runoff uplifting over geologic time TERRESTRIAL ROCKS
Figure 48.23, Page 884
Human Impact on Ecosystems
Increased Eutrophication of Lakes Increase in nutrient levels (phosphates, nitrates, etc.) Can lead to algal blooms Hypoxia What is it?
Why?
Can lead to the eventual loss of fish and other aquatic organisms Accelerated by sewage/factory wastes, leaching of fertilizers into freshwater
Human Impact on Ecosystems
Combustion of Fossil Fuels Leads to acid precipitation Changes the pH of aquatic ecosystems and affects the soil chemistry of terrestrial ecosystems
Human Impact on Ecosystems
Biological Magnification Toxins become more concentrated as they move up the food chain Toxins that are lipophilic cannot be excreted in urine (water!), so they are stored in fatty tissue (adipose tissue) unless the organism has enzymes to break it down Important examples?
The biomass at any given trophic level is produced from a much larger biomass ingested from the level below
Human Impact on Ecosystems
Increasing Carbon Dioxide Concentration in the Atmosphere Burning fossil fuels (wood, coal, oil) releases CO 2 Carbon dioxide and water in the atmosphere retain solar heat, causing the greenhouse effect
Human Impact on Ecosystems
Use of chlorofluorocarbons has destroyed ozone (O 3 ) by converting it to oxygen gas.
Ozone protects against UV radiation Increasing skin cancers, cataracts What are your odds of getting skin cancer in your lifetime?
Rain Shadow
Air rises on the windward side, loses moisture before passing over the mountain Leeward side is in the rainshadow; deserts
Figure 49.7
Page 893
Biomes
Regions of land characterized by habitat conditions and community structure Distinctive biomes prevail at certain latitudes and elevations
Tropical Forests
May be dry, deciduous, or rainforests T. Rainforest Abundant rainfall 4 layers to forest (upper & lower canopy, shrub understory, & herbaceous layer) Poor soil due to leaching Highest species diversity
Grasslands
Savannas Tropical & subtropical with scattered trees 3 seasons: cool & dry; hot & dry; warm wet.
Frequent fires Grazing mammals (African grasslands)
Chaparral
Along coastlines in mid latitudes Mild, rainy winters & hot, dry summers Evergreen shrubs Periodic fires Browsers, rodents reptiles
Temperate Grassland (Prairie)
Similar to savannah without trees Cold winters Maintained by fire Seasonal drought Rich soils Grazing animals; herbivores
Temperate Deciduous Forest
Our biome 3 layered forest Dominant species are deciduous trees Midlatitudes
Deserts
Less than 10 centimeters annual rainfall, high level of evaporation Tend to occur at 30 degrees north and south and in rain shadows One-third of land surface is arid or semiarid
Arctic Tundra
Occurs at high latitudes Permafrost lies beneath surface Nutrient cycling is very slow Coldest biome Low species diversity Do not post on Internet Arctic tundra in Russia in summer Figure 49.19
Page 903
Taiga (coniferous forest)
Found in northern latitudes Harsh winters; short summers Thin, acidic soil Coniferous trees No permafrost
Alpine Tundra
Occurs at high elevations No underlying permafrost Plants are low cushions or mats as in Arctic tundra
Do not post on Internet Figure 49.19
Page 903
Lakes
Bodies of standing freshwater Eutrophic: shallow, nutrient-rich, has high primary productivity, Oligotrophic: deep, nutrient poor, has low primary productivity
LITTORAL
Lake Zonation
LIMNETIC PROFUNDAL LITTORAL Figure 49.21
Page 904
Thermal Layering
In temperate-zone lakes, water can form distinct layers during summer THERMOCLINE
Figure 49.22
Page 904
Seasonal Overturn
In spring and fall, temperatures in the lake become more uniform Oxygen-rich surface waters mix with deeper oxygen-poor layers Nutrients that accumulated at bottom are brought to the surface
Ocean Provinces
neritic zone oceanic zone intertidal zone Figure 49.24
Page 906 continental shelf BENTHIC PROVINCE bathyal shelf PELAGIC PROVINCE 0 200 1,000 2,000 abyssal zone hadal zone 4,000 deep-sea trenches 11,0000 depth (meters)
Phytoplankton
Floating or weakly swimming photoautotrophs; form the base for most oceanic food webs Ultraplankton are photosynthetic bacteria
Hydrothermal Vents
Openings in ocean floor that spew mineral-rich, superheated water Primary producers are chemoautotrophic bacteria; use sulfides as energy source
Do not post on Internet Tube worms at hydrothermal vent Figure 49.26
Page 907
Estuary
Partially enclosed area where saltwater and freshwater mix Dominated by salt-tolerant plants Examples are Chesapeake Bay, San Francisco Bay, salt marshes of New England
Estuarine Food Webs
Primary producers are phytoplankton and salt tolerant plants Much primary production enters detrital food webs Detritus feeds bacteria, nematodes, snails, crabs, fish
Intertidal Zones
Littoral zone is submerged only during highest tides of the year Midlittoral zone is regularly submerged and exposed Lower littoral is exposed only during lowest tides of the year
Rocky Intertidal
Grazing food webs prevail Vertical zonation is readily apparent Diversity is greatest in lower littoral zone
Figure 49.29
Page 909 Do not post on Internet
Upwelling
Upward movement of water along a coast; replaces surface waters that move away from shore
Figure 49.31
Page 910