Ecosystems and Energy

Energy Flow in Ecosystems

Energy flows, but matter is recycled

Matter and Energy

• Energy enters, flows through, and exits an ecosystem

• Chemical nutrients cycle within ecosystems through biogeochemical cycles (carbon, nitrogen, phosphorus, water)

Matter and Energy

• Energy enters from the sun as radiation, moves as chemical energy transfers through food webs, and exits as heat radiated back into space

Matter and Energy

Energy Flow

• Energy flows through ecosystems from the sun through producers to consumers

• Organisms within food webs and food chains interact

• Food webs and food chains are dependent on primary productivity

Primary Producers (Phototrophs)

• Plants, photosynthetic protists (algae), chemosynthetic and photosynthetic bacteria (cyanobacteria)

• Convert solar energy into chemical energy (glucose) through photosynthesis

Primary Producers (Chemotrophs) • Chemosynthetic bacteria (prokaryotes) are the

primary producers of the deep-sea hydrothermal vent communities

• Convert inorganic chemicals (CO2, H2S, CH4) into organic molecules (sugars) through chemosynthesis

Primary Productivity

• Primary productivity: The amount of light energy converted to chemical energy (organic molecules) by autotrophs (photosynthetic and chemosynthetic) during a given time period in an ecosystem

• Starting point for ecosystem metabolism

• Influenced by changes in regional and global climates and in atmospheric composition

Primary Productivity

• Food webs and food chains are dependent on primary productivity – why?

• Represents the storage of chemical energy that will be available to consumers in an ecosystem

GPP and NPP

• Gross primary productivity (GPP): total primary production in an ecosystem (the amount of energy from light, or chemicals, converted to chemical energy of organic molecules per unit time

• Net primary productivity (NPP): equal to the GPP minus the energy used by the primary producers for autotrophic respiration

Net Primary Productivity (NPP)

Global Primary Production

Terrestrial Primary Production

Terrestrial Primary Production • Temperature and moisture are the main

factors controlling primary production in terrestrial ecosystems

Aquatic Primary Production

Aquatic Primary Productivity

• Ocean phytoplankton are responsible for approximately 50% of the global biosphere net primary production

• Global annual ocean primary production has decreased due to an increase in global sea surface temperature – why? (thermocline)

• Light and nutrients are limiting factors

Light and Nutrient Limitation

• Solar radiation drives photosynthesis (not the only variable controlling primary production)

• Limiting nutrients are elements that must be added for production to increase, such as nitrogen and phosphorus

Calculating Primary Production

• Use the textbook to explain how to calculate primary production in your notes.

• Write down the equation in your notes.

• More math….yes!!

Consumers (Heterotrophs)

• Herbivores, carnivores, omnivores, detritivores, decomposers

Role of Decomposers

Trophic Levels and Ecological Pyramids

Trophic Levels

• A trophic level is the position that an organism occupies in a food chain or food web (what it eats, what eats it)

Ecological Pyramids

• Graphical representations designed to show the biomass or bioproductivity at each trophic level in a given ecosystem

• Energy pyramid, biomass pyramid, and pyramid of numbers

Energy Pyramid

• A graphical representation of energy flow in a community of organisms

Trophic Efficiency

• Trophic efficiencies are generally only about 10% (90% of the energy available at one trophic level not passed on)

Trophic Efficiency

Pyramid of Net Production

Biomass Pyramid and Numbers Pyramid

• Biomass pyramids represent the total dry mass of all organisms in one trophic level

• Numbers pyramids show the number of individual organisms in one trophic level

• By the way, I really miss school and you all! I’m sorry that you have to learn Ecology on your own, but you are all super smart and I know you can do it! Hang in there. I hope you all have a nice Thanksgiving break.

Mrs. Simpson

Ok, now on with the note taking…..

Biogeochemical Cycles

Cycle inorganic and organic nutrients between organisms and the

environment

Cycling of Matter

• Organisms must exchange matter with the environment to grow, reproduce and maintain organization

• Molecules and atoms from the environment are necessary to build new molecules

Molecules Essential for Life

• Carbohydrates – composed of C, H, and O, monomer is a monosaccharide

• Lipids – composed of C, H, and O, monomers are fatty acids and glycerol

• Proteins – composed of C, H, O, N, and S in trace amounts, monomers are amino acids

• Nucleic Acids – composed of C, H, O, N and P, monomers are nucleotides

Carbon

• Carbon moves from the environment to organisms where it is used to build the essential organic molecules

• Carbon is used in storage compounds and cell formation in all organisms

Carbon in the Environment

• Carbon found in something non-living is called inorganic carbon

• Inorganic carbon is found in rocks (limestone), shells, the atmosphere and the oceans

• Living organisms must “fix” inorganic carbon into organic carbon to build the organic compounds necessary for life

Carbon Cycle – Draw a diagram of the carbon cycle in your notes.

Nitrogen and Phosphorus

• Nitrogen moves from the environment to organisms where it is used to build proteins and nucleic acids

• Phosphorus moves from the environment to organisms where it is used to build nucleic acids, certain lipids, and ATP (cell energy)

Nitrogen in the Environment • The main reservoir for inorganic nitrogen is the

atmosphere – 80% nitrogen gas (N2)

• During nitrogen fixation, bacteria (and other processes) fix inorganic nitrogen into forms that can be used by living organisms to synthesize organic compounds

Nitrogen Cycle – Draw a diagram of the nitrogen cycle in your

notes.

Phosphorus in the Environment

• Most inorganic phosphorus in found in sedimentary rock of marine origin

• Phosphorus is also found in soil and dissolved in the oceans

• Weathering of rocks adds phosphates (PO43-)

to the soil which plants can absorb

Phosphorus Cycle – Draw a diagram of the phosphorus cycle

in your notes

Water

• Living systems depend on the properties of water that result from its polarity and hydrogen bonding

• Living organisms are mostly made of water (think cytoplasm and extracellular fluids!)

• Universal solvent supports cell reactions

• Acts as a delivery system between cells

Water Cycle – Draw a diagram of the water cycle in your notes

Water Cycle