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ENERGY FLOW THROUGH AN ECOSYSTEM. Nutrition and the Flow of Energy through Food Webs and Food Chains. Energy. Energy in an ecosystem ultimately comes from the sun Energy flows through Ecosystems from producers to consumers Producers (make food)
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ENERGY FLOW THROUGH AN ECOSYSTEM Nutrition and the Flow of Energy through Food Webs and Food Chains
Energy • Energyin an ecosystem ultimatelycomes from the sun • Energy flows through Ecosystemsfrom producers to consumers • Producers(make food) • Consumers (cannot make food; must eat producers or other consumers)
ENERGY IN AN ECOSYSTEM • Classification of organisms according to how they obtain their energy: • Autotrophs= Producers – organisms that use the sun’s energy or chemical energy to make their own food; carry out photosynthesis • Heterotrophs = Consumers – organisms that depend on producers either directly or indirectly for their food.
Sunlight Autotroph • Sunlight is the main source of energy for most life on earth. • Most producers contain chlorophyll & can use energy directly from the sun = Photosynthesis
AUTOTROPHS • All green plants and some unicellular organisms which contain chlorophyll such as algae. • Producers use most of the energy they make for themselves through the process of cellular respiration (the chemical reaction that releases energy in glucose).
AUTOTROPHS (cont’d) • Two Types: • Photoautotrophs– use light energy to produce energy; carry out photosynthesis, adding oxygen to air and removing carbon dioxide (i.e. plants on land, algae in the sea) • Chemoautotrophs – use chemical energy captured from the bonds of inorganic molecules such as Hydrogen sulfide (chemosynthesis); often occurs in deep sea vents
Tube Worms living in Black Smoker (thermal vent)
The energy that is not used by autotrophs (producers) can be passed on to heterotrophs (consumers) which are organisms that cannot make their own energy.
HETEROTROPHS • Herbivores – only eat plants – rabbits, cows, mice, squirrels • Carnivores – eat other animals – cougars, wolves, birds of prey • Omnivores – eat both plants and animals – humans, bears, chimpanzees • Detritivores (Scavengers)– feed on dead animals – vultures, buzzards • Decomposers – break down the complex compounds of dead and decaying plants and animals – bacteria, fungi, some protozoans
Feeding Relationships Energy flow through an ecosystem in one direction from producers to various levels of consumers
FOOD CHAINS & FOOD WEBS • Food Chain – a model that uses arrows to show directional flow of matter and energy through an ecosystem; usually 3-5 links due to loss of energy at each link; each organism represents a feeding step or TROPHIC LEVEL. • Food Web – occurs when many food chains combine and overlap; more natural models since most organisms depend on more than one species for food; shows feeding relationships in an ecosystem.
Food Chain 1st order Consumer 2nd Order Consumer 3rd Order Consumer 4th Order Consumer Producer(trapped sunlight & stored food)
TROPHIC LEVELS Each Level In A Food Chain or Food Web is a Trophic Level. Each level depends on the one below it for energy. • Producers -Always The First Trophic Level -How Energy Enters The System • Herbivores/Omnivores -Second Trophic Level • Carnivores/Omnivores -Make Up The Remaining Trophic Levels
1sttrophic level – autotrophs / producers 2ndtrophic level – first order consumers / herbivores / 1o consumers 3rdtrophic level - second order consumers / carnivores / 2o consumers 4thtrophic level – third order consumers / carnivores / tertiary consumers Examples: SUNGRASSMOUSEHAWK SUNALGAEFISHGREAT BLUE HERONALLIGATOR TROPHIC LEVELS
ENERGY OR ECOLOGICALPYRAMIDS • A graphic representation that shows that the relative amount of energy or matter decreases at each trophic level. • Some energy is lost at each level as heat. • The base represents producers at the bottom – the amount of biomass (organic material) needed to support the pyramid.
Different Types of Pyramids 1.Energy Pyramid 2. Biomass Pyramid 3. Pyramid of Numbers
ENERGY LOSS IN THE PYRAMID • As energy is passed from one level to the next, 90% of it is “wasted” as heat. • Only 10% of the energy from the previous level is available at the next level. • As the available energy decreases, the population size decreases as well.
