Section 3 – Ecological Communities
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Transcript of Section 3 – Ecological Communities
Section 3 – Ecological Communities
Producers and ConsumersEnergy: the ability to do work
Energy cannot be created or destroyed, only changed from one form to anotherSolar Energy – Thermal Energy – Absorbed by a
Beach or a Dark T-ShirtAll energy in the world remains constant (like the
amount of matter in the world)Primary Producer: an organism that can
capture energy from the sun or from chemicals and store it; also called autotroph
Energy from the SunPhotosynthesis: the process by which primary
producers use sunlight to convert carbon dioxide and water into sugars, releasing oxygen
Primary ProducersGreen PlantsAlgaeCyanobacteria
6CO2+6H2O+light energy ->C6H12O6(sugar)+6O2
Energy From ChemicalsChemosynthesis: the process by which
bacteria use energy stored in bonds of hydrogen sulfide to convert carbon dioxide and water into sugars
Deep Sea Vents – communities of organismsNo SunlightPrimary Producers use energy stored in Hydrogen
Sulfide H2S, to make Carbon Dioxide and Water
6CO2+6H2O+3H2S -> C6H12O6(sugar)+3H2SO4
ConsumersConsumer: an organism that relies on other
organisms for energy and nutrients; also called heterotroph
Cellular Respiration: the process by which organisms use oxygen to release the chemical energy of sugars, producing carbon dioxide and water
C6H12O6(sugar)+6O2 -> 6CO2+6H2O+energyOpposite of Photosynthesis
Herbivores, Carnivores, and Omnivores
Primary Consumers: organisms that consume producers, most are herbivoresHerbivore: an organism that eats plants
Secondary Consumers consume Primary Consumers, and so on. Most are carnivoresCarnivore: an animal that kills and eats other
animalsOmnivore: an animal that eats both plants
and animals
Detritivores and DecomposersDetritivore: an organism (e.g., a millipede or
soil insect) that scavenges the waste products or dead bodies of other community membersScavengers: large detritivores, like vultures
Decomposer: an organism (e.g., a fungus or bacterium) that breaks down nonliving matter into simple parts that can be taken up and reused by primary producers
Energy and BiomassTrophic Level: a rank in a feeding hierarchyPrimary Producers
Primary ConsumersSecondary Consumers
Tertiary ConsumersNo process of energy conversion is 100%
efficientGasoline burned in an engine, 14% is used
to move the car down the road, the rest is converted to thermal energy and released (“lost”) as heat.
Energy Transfer in Communities
10% Rule: each trophic level contains just 10% of the energy of the trophic level below it
Primary Producers = 100 calories10 calories available to level 21 calorie to level 30.1 calories to level 4
Eating lower trophic level food (fruits and veggies) rather than consumers (meat) decreases a person’s ecological footprint.
Numbers and BiomassBiomass: the total amount of living tissue in a
trophic levelGenerally, there are fewer organisms at higher
trophic levels.A mouse eats many plants in its lifetime.A snake eats many mice.A hawk eats many snakes.
Food Webs and Keystone Species
Food Chain: a linear series of feeding relationships
Energy transferred from species on lower trophic levels to species on higher trophic levels
Food WebsFood Web: a visual map of feeding
relationships and energy flowEcological systems far more complex than linear
chains
Keystone SpeciesKeystone Species: a species that has a strong or
wide-ranging impact on a communityThe wedge at the top of the arched stone structure,
if you take it out the whole thing collapses.Sea otters eat Urchins – Urchins eat Kelp
In the 1990’s, sea otter population declined Urchin population increased Kelp “forest” declined dramatically
Trophic Cascade: predators at high trophic levels (sea otters) indirectly help organisms at low trophic levels (kelp) by limiting populations at intermediate levels (urchins)