Energy Flow in the Biosphere Energy Flow Energy Balance Trophic Levels Ecological Pyramids Biosphere

Energy Flow Energy flows through the biosphere in a one-way path and is ultimately lost as heat one-way path – It is not cyclic 1 st Law of Thermodynamics – Energy is neither created nor destroyed but can be converted from one form to another 2 nd Law of Thermodynamics – When energy is converted to another form, some is released as heat Since energy can be lost as heat, we need a constant supply of energy  The Sun

Energy Flow In the biosphere, producers capture energy in a given environment Only a fraction of the Sun’s energy is available for these producersfraction

Energy Flow Producers Capture energy and convert it into energy-rich molecules They do this by two major processes

Energy Flow 1.PhotosynthesisPhotosynthesis – The process by which plants, algae, and some bacteria (Autotrophs) use the Sun’s energy to convert CO 2 gas into high energy carbohydrates – 6 CO 2 (g) + 6 H 2 O (l) + LE  C 6 H 12 O 6 (s) + 6 O 2 (g) 2.ChemosynthesisChemosynthesis – The process by which certain fungi and bacteria (Chemoautotrophs) use energy from inorganic chemicals (H 2 S) and convert it into high energy carbohydrates in the absence of light

Energy Flow Consumers Heterotrophs that consume other heterotrophs or autotrophs Utilize the process of cellular respiration to obtain energy C 6 H 12 O 6 (s) + 6 O 2 (g)  6 CO 2 (g) + 6 H 2 O (l) + energy Heat energy is released during this process

Energy Flow E Flow in a Photosynthetic Environment 1.Solar energy/radiation enters the biosphere 2.Plants use photosynthesis to convert the solar energy/radiation into the bonds of various organic chemicals 3.Animals consume plants and other animals 4.Decomposers then consume the dead remains and excrement Energy in the form of heat is released at each step

Energy Flow E Flow in a Chemosynthetic Environment 1.Bacteria use the thermal energy from sea vents to convert energy in H 2 S into organic compounds 2.Bacteria are consumed by various heterotrophs 3.Heterotrophs are consumed by predators 4.Decomposers consume the dead remains and excrement Energy in the form of heat is released at each step

Energy Balance The Earth’s environment is always in a state of dynamic equilibrium: A state of constant change in which the components can adjust to the changes in a way that does not disturb the whole system Photosynthesis and Cellular Respiration are complementary processes The products of photosynthesis (Glucose and Oxygen) are the reactants of cellular respiration Vice-Versa for the products of CR and reactants of PS The same principle applies for chemosynthesis

Energy Balance Therefore, the energy within an ecosystem is balanced between photosynthesis and cellular respiration What are some things we are doing that are affecting this equilibrium? What evidence suggests negative effects on the ecosystem?

Energy Balance Indicator Species A species sensitive to small changes in an ecosystem Provide early warning of that the balance in an ecosystem is being negatively affected Frogs Strongly influenced by external factors because they live part of there life-cycle in water and part on land Very sensitive to changes

Biosphere “Life-Dome” The zone around the Earth that harbours life Contains three major zones: Lithosphere (Land) Hydrosphere (Water) Atmosphere (Air)

Biosphere The biosphere contains: Biotic Components The biological or living components Humans, Plants, Dogs, Insects, etc Abiotic Components The non-living components Are both chemical and physical Minerals, Rocks or Temperature, Weather Both are essential to studying life on Earth

Trophic Levels Ecosystems contain much biodiversity and as a result food chains develop Food chains are a sequence of linking organisms that feed on each other Trophic Level “Nourishing Level” A category defined on how an organism obtains its energy Producers - Organisms that make their own food (Autotrophs) Consumers - Organisms that must eat producers or other consumers to survive (Heterotrophs) Decomposers - Organisms that feed on waste and dead remains and in the process release nutrients to the soil and water

Trophic Levels There are numerous types of consumers: Herbivores Animals that feeds only on plants Carnivores An animal that feeds only on other animals Omnivores An animal that eats both plants and other animals Scavengers Do not kill but feed off the carcasses of other animals

Trophic Levels 1 st Trophic Level Producers/Autotrophs Plants, Algae, Bacteria 2 nd Trophic Level Primary Consumers Relies directly on autotrophs for its source of energy Mice, Deer, Elk, Cattle 3 rd Trophic Level Secondary Consumers Relies directly on primary consumers for its source of energy Coyote, Wolf, Bear

Trophic Levels Food Chains A step-by –step sequence of who eats whom in an ecosystemstep-by –step Energy is lost a each step in the form of heat, waste, and dead material ~10% of the energy is transferred to the next level The higher the position in the food chain, the lower the amount of energy consumed

Trophic Levels Grazer Food Chain Initiates with herbivores consuming plants Detritus Food Chain Initiates with scavengers consuming wastes and remains from dead organisms

Trophic Levels Food Web A series of interlocking food chains that represents the transfer of energy in a ecosystem An organism relies on multiple sources of food that is not properly represented by a typical food chain The most stable ecosystems have complex and well developed food websfood webs Depletion of one organism has serious effects on the food web

Trophic Levels Factors Affecting Food Webs Loss of Habitat Air and Water Quality Climate Change UV Radiation Hunting and Fishing Monocultures Pollutants

Trophic Levels Bioaccumulation The accumulation of a substance in an organism Usually in the form of toxins, pesticides, and pollutants Biomagnification The amplification of a substance within a food chain as a result of animals consuming other animals in which that substance has bioaccumulated Toxins, pesticides, and pollutants

Ecological Pyramids Representations of energy flow in food chains and food webs 1.Pyramids of NumbersPyramids of Numbers 2.Pyramids of BiomassPyramids of Biomass 3.Pyramids of EnergyPyramids of Energy

Ecological Pyramids Pyramids of Numbers A graphical representation of the number of organisms at each trophic level in an ecosystem Form can vary according to ecosystemvaryecosystem

Ecological Pyramids Pyramids of Biomass Biomass The total dry mass of all the living material in an ecosystem A graphic representation of the biomass at each trophic level in an ecosystem Can vary according to ecosystemvary ecosystem

Ecological Pyramids Pyramids of Energy At each trophic level, energy is released in the form of heat, waste, and dead material Therefore, less energy is transferred to the next trophic level when one is consumed In general, 10% of the energy from one trophic level does not pass to the next (ie. Lost as heat, waste, or dead material) Energy is measured in kilojoules (kJ)