Bell Ringer, 8/14 • TURN IN ANY WORK THAT YOU ARE MISSING • Pick up your Exit Slips on the back lab table • Answer the following question on your bell ringer: • Explain the difference between a hypothesis and a guess.
Bell Ringer, 8/15 • Retrieve your EXIT SLIPS from the back lab table • Answer the following questions: • In one food chain, a cat eats a mouse, which ate some cheese. In another food chain, a lion eats a meercat that ate some desert grass. • Are the cat and the lion on the same trophic level? Defend your answer. • What type of CONSUMER OR PRODUCER is each organism in the above food chains?
Detritivores vs. Decomposers • The two groups are very, very similar • DETRITIVORES help break organic wastes into smaller pieces, but they DO NOT actually get rid of it • DECOMPOSERS break organic wastes back into its basic nutrients and return it to the environment • DETRITIVORES can ingest clumps of matter while DECOMPOSERS cannot
Ecosystems: an overview (Chapter 47.1-2)
What is an ecosystem? • An array of organisms and a physical environment, all interacting through a one-way flow of energy and cycling of nutrients • Ecosystems run on energy • Primary producers: Capture energy from a non-living source (typically sunlight) • Consumers: Get energy from feeding on tissues, wastes, or remains of producers and other consumers
Primary Producers • Main primary producers: Plants and photoplankton • Autotroph: Produces its own food from inorganic substances • Capture energy from the sun (photosynthesis) or create energy from chemicals (chemoautotrophs)
Primary Producers Common misconception: All plants are autotrophs NOT ALL PLANTS ARE AUTOTROPHS
Consumers • Heterotroph: Consumers other organisms to get energy • Can be classified based on their diets • Herbivores: Eat plants • Carnivores: Eat the flesh of animals • Parasites: Live inside or on a living host and feed on its tissues • Omnivores: Eat both plant and animal materials • Detritivores: Eat small particles of organic matter (detritus) • Decomposers: Eat organic wastes and remains
Flow in an Ecosystem • Energy flow in an ecosystem only goes ONE WAY • Light capturelivingcomponentsphysical environment • Breaking down food in the ecosystem gives off heat • Heat cannot be recycled, making this a one-way process
Flow in an Ecosystem • Many nutrients cycle in an ecosystem • Producers take up nutrients (N, H, O, C) from inorganic sources (air, water) • Nutrients move into consumers as they eat the producers • After organisms die, decomposition returns nutrients to environment • Producers pick them up again http://www.youtube.com/watch?v=bW7PlTaawfQ
Trophic Levels • Trophic level: One level in the hierarchy of feeding relationship present in all ecosystems • When an organism eats another, this energy transfers up to the next trophic level • All organisms in a trophic level are the same number of transfers away from the energy input into that system Same trophic level
Can one organism be on one trophic level in one food chain and a different trophic level in another?
Are they on the same trophic level? • A bird eating a worm and a Venus fly trap catching a fly • A cow eating grass and a cat eating a mouse • A human eating a steak and a lion eating an antelope • A mouse eating a piece of cheese and another mouse eating some kudzu • A bacteria and fungi breaking down the same weasel
Exit Slip 8/14 • Draw and label FOUR trophic levels. Include each type of PRODUCER or type of consumer.
Food Chains • Sequence of steps by which some energy captured by primary producers is transferred to organisms as successively higher trophic levels • Simple way to think about who eats who in an ecosystem • More than one per ecosystem; often complex
Name those trophic levels! • AcornSquirrelHawk • GrassBunnyFoxBear • FlowerSheepWolfLionFungi • Star flowersFairiesUnicornsUnicorn ticks THE POINT: The levels are always named the same way, even in a ridiculous example!
Food Webs • Diagram that illustrates trophic interactions among species in a particular ecosystem • Includes multiple connecting food chains
Food Webs • Detrital food chain: Energy stored in producers flows to detritivores • Majority of land ecosystems • Small amounts of plant matter get eaten, but far more becomes detritus (ex. Leaves falling from trees in fall) • Grazing food chain: Energy stored in producer tissues flows to herbivores • Predominate aquatic food chains • Zooplankton (primary consumer) consumes most of the primary producer so very little ends up as detritus
Food Webs • Ecologists use food webs to predict how species will relate to one another • On average, each species in a food web is only two links away from another • “Everything is linked to everything else.” –Neo Martinez • Thus, the extinction of any species in a food web may have an impact on MANY other species
Energy Transfer • Energy captured by producers passes through NO MORE than five trophic levels, even in complex ecosystems • Energy is limited • Rule of 10: Only 10% of energy is passed up to the next trophic level • Ex. Bears vs. bunnies
Energy Transfer • Food chains are shorter where conditions vary widely over time • Food chains are longer where conditions are stable (ex. Ocean depths)
You try it! • Draw a food chain. Include: • Primary producer • Primary consumer • Secondary consumer • Tertiary consumer • Quaternary consumer • You food chain should be CREATIVE and NEATLY LABELED • Have fun!
Exit Slip 8/13 • Create a food chain for an aquatic environment. Include AT LEAST four trophic levels. Label each trophic level and tell whether the organism is a PRODUCER or a CONSUMER
Energy flow through ecosystems Chapter 47.3
Bell Ringer, 8/20 • Get your EXIT SLIP and ECOSYSTEM DRAWING from the second lab table • On your bell ringer sheet, fill in the chart on the white board.
Energy Capture and Storage • Primary Production: Rate at which producers capture and store energy • Gross Primary Production: Amount of energy captured by ALL producers in an ecosystem • Net Primary Production: Portion of energy that producers invest in growth and reproduction (rather than maintenance)
Energy Capture and Storage If three plants each capture and store 30 joules of energy and invest 20 joules in growth and reproduction… • What is their gross primary production? • What is their net primary production?
Energy Capture and Storage If 10 plants capture 100 joules of energy each and invest 50 joules of energy in maintenance each… • What is their gross primary production? • What is their net primary production?
Energy Capture and Storage • Factors that affect primary production: • Temperature • Availability of water • Availability of nutrients • Net primary production on land is higher, but there are more oceans so they contribute nearly half of earth’s global net primary productivity
Ecological Pyramids • Show the trophic structure of an ecosystem • Biomass pyramid: Shows the dry weight of all the organisms at each trophic level in an ecosystem • Usually primary producers are on bottom (more grass than bears) • Exception: Aquatic ecosystems where primary producers reproduce quickly (single-celled protists)
Ecological Pyramids • Energy pyramid: Shows how the amount of USABLE energy in an ecosystem diminishes as it is transferred through an ecosystem • Primary producers on base (capture sunlight) • Energy diminishes as you move up the pyramid • Pyramids are always “right side up”
Ecological Efficiency • Factors that influence the efficiency of transfer: • Consumers don’t use all their energy to build biomass • Some energy is lost as heat • Not all biomass can be consumed by consumers • Herbivores: Can’t break down ligand and cellulose • Hair, feathers, bones, external skeletons, and fur are usually indigestible
Ecological Efficiency • Aquatic ecosystems usually have higher efficiency than land ecosystems • Algae lack ligin • Higher proportion of ectotherms • Ectotherms: “Cold blooded” animals that get their body heat from external sources • Don’t lose as much heat as endotherms (“warm blooded” animals that maintain their body temperature internally)
Biological Magnification • Process by which a chemical that degrades slowly or not at all becomes increasingly concentrated in tissues of organisms as it moves up a food chain • Example: DDT in eagles
Now you try it! • For the ecosystem that you drew on Friday… • Make an ecosystem chart • Make a biomass pyramid • Make an energy pyramid
Exit Slip, 8/19 • Explain why aquatic ecosystems tend to have higher efficiency than land ecosystems. • What is the difference between an energy pyramid and a biomass pyramid? Draw an example of each.
Biogeochemical cycles Chapter 47.5-.10
Bell Ringer, 8/22 • Get out your lab handouts. • Find your NEW SEAT. Your name will be written in ORANGE MARKER. • Tear off (and throw away!) the old taped name tags. You are free from their tyranny!!! • On your bell ringer paper, answer the following questions. • Explain the concept of biological magnification. • What factors influence the efficiency of energy transfer between trophic levels?