Ecology: Energy Flow and Nutrient

Cycles

Essential Questions:How does Energy Flow through the Earth?How do Nutrients Cycle through the Earth?

How are these processes related to each other to sustain life on Earth?

What is Energy? Recap!• Remember the source of all energy comes from the

Sun.• Also, one requirement of all living things is to use

energy for cell processes!

• How do we Calculate and Show how that energy is distributed through nature? – First we need to know what energy flow is.– Then how energy flows through the Earth.

Autotrophs trap that energy and convert it into chemical energy (sugar) through photosynthesis.

Heterotrophs obtain that energy by consuming autotrophs or other heterotrophs and release it through cellular respiration.

What is Energy Flow?

• Energy and matter passes through ecosystems when organisms metabolize other organisms.

Key Vocabulary:• Producers: organisms which produce their own food, also called

autotrophs. (Plants, Algae, Phytoplankton, etc)• Consumers: organisms which obtain their food from other

organisms, also called heterotrophs. (Everything else!)– Primary consumers consume producers.– Secondary consumers consume other consumers

• Detritivores: feed on plant and animal remains and other dead matter.

• Decomposers: organisms which break down dead and decaying matter.

Energy Flows in One Direction

Sun or inorganic compounds

Autotrophs (producers)

Heterotrophs eat the autotrophs (consumers)

Heterotrophs eat other heterotrophs (carnivores)

In this example black dots represent energy units.

How much energy is stored/ transferred?So, How much of the sun’s energy ends up in the food we eat?

10% Rule:

10% of energy at one trophic level can be used by consumers at the next trophic level.

Trophic Level:Each step in a feeding relationship.

This means that 90% is lost…

Where does all of the energy go?!

Where does the “lost” energy go?

What do these images show?Energy is “lost” when paper burns. Where does the energy go? How do you know?

How much of the sun’s energy ends up in the food we eat?

Table of Contents

Which foods require the most energy to make? What does this mean for humans as top-level consumers?

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How much of the sun’s energy ends up in the food we eat?

Join this friendly farmer for lunch to talk about how the sun's energy reaches your plate!

How much of the sun’s energy ends up in the food we eat?

"Three hundred trout are needed to support one man for a year. The trout, in turn, must consume 90,000 frogs,

…that must consume 27 million grasshoppers …that live off of 1,000 tons of grass."

What is the energy advantage to being a primary consumer rather than a secondary consumer?

Which foods require the most energy to make? What does this mean for humans as top-level consumers?

How can we display this data in a logical manner?

Displaying Data: Ecological Pyramids• Represent relationships among trophic levels, each

reducing at higher and higher levels.– Energy: amount of incoming energy.– Biomass: mass of living tissue.– Numbers: number of organisms.

What is Nutrient Cycling?

• Biogeochemical cycles: passage of matter from one organism to another in the biosphere.

• Nutrients are finite (not like the Sun which supplies constant energy), so they must be (re)cycled through various parts of nature.– Relies heavily on Decomposers and movement

through the cycle (not getting “stuck” in one area)

• The Five (5) Major Biogeochemical Cycles:– Carbon, Water, Nitrogen, Sulfur, Phosphorous.

Cycles of Nature: The Carbon Cycle

• Carbon is the building blocks of life. – Definition of “Organic”

• CO2 = Carbon Dioxide

• Living things take in Oxygen and give off CO2 through Aerobic or Cell Respiration.

• Plants take in CO2 through

photosynthesis and produce Oxygen.

• Organisms/Living things contain the most carbon in the Carbon cycle.

• As organisms die and enter the soil, they eventually become fuel over millions of years (“fossil fuels.”)

• Natural Processes of Volcanoes give off CO2

Where do we find carbon?

How Humans affect the Carbon Cycle

• Greenhouse Gases– Excess CO2 in the atmosphere acts as a trap for heat and water vapor.

• Global Warming – Warming of the Earth causes ice caps to melt, causing the ocean to

change temperature and salinity, raising sea levels, changing climate & weather.

• Deforestation and Habitat Destruction– Without Trees to undergo photosynthesis to convert CO2 to Oxygen, Carbon levels will continue to rise. - Removal of trees also harms biodiversity (the amount of different organisms) and habitats for organisms.

Cycles of Nature: The Water Cycle

• Evaporation – Water taken into the atmosphere

• Transpiration – Plants losing water through leaves

• Precipitation – Water that falls from the atmosphere (rain, snow, hail, etc)

• Runoff – Water that enters the ocean

• Groundwater – Water that is absorbed into the ground

• Water vapor is also given off by volcanic eruptions.

• The Water Cycle helps cool the Earth preventing large changes in Global Temperatures.

How Humans affect the Water Cycle

• Human Use of Water:– Agriculture– Dams and Deforestation– Urbanization (Living in Cities)– Overuse of Aquifers

• Saltwater Intrusion (ocean)• Subsidence (lead to collapse)

• Clean Water supply– 1 billion people (16%) do not have any access to clean water.– Can cause outbreaks of disease

• Examples: cholera, hepatitis, mosquito breeding, etc.

• Acid Rain (in combination with Nx and Sx)– Hurts plants, animals and buildings

Cycles of Nature: The Nitrogen Cycle

• 78% of the air is Nitrogen• Plants use nitrogen in their

cellular processes• Nitrogen is present in our DNA

and RNA and in amino acids (proteins).• The food chain largely moves

Nitrogen around.• Bacteria and Lightning takes

Nitrogen gas and puts into a useable form (called Nitrogen Fixation)

• Bacteria have a mutualisitic relationship with plants and live on their roots.

How Humans affect the Nitrogen Cycle• Humans contribute extra Nitrogen in the cycle due

to fertilizers and animal waste (hog lagoons) that runoff into in the lakes and rivers.

• Extra Nitrogen in the groundwater can interfere with blood/oxygen levels and cause blue-baby syndrome.

• Excess Nitrogen can cause Eutrophication which causes aquatic life to die due to…– the low levels of oxygen (fish kills) – extra algae to grow (algal bloom.)

• High levels of ammonia is also toxic to animals.

Cycles of Nature: Sulfur Cycle• important part of amino acids/proteins and plays role in

forming shape of molecules• most sulfur is trapped in rocks and is broken down then

taken up by plants– organisms eat the plants and take up S– organisms release S into the atmosphere through

decomposition as Hydrogen Sulfide (H2S)

Human Impacts on the Sulfur Cycle: • Hydrogen sulfide combines with oxygen to form H2SO4,

sulfuric acid; falls to the earth as acid rain. • The burning of fossil fuels release SO2; combines with

atmospheric H2O and O2 to form acid rain.

Cycles of Nature: Phosphorus Cycle• Phosphorus is found in bones,

teeth, DNA, and ATP (energy-storing molecule)

• Naturally, phosphorus is found in rocks as calcium phosphate (Ca3(PO4)2)

• As the rocks break down, phosphate is released into the soil where it is taken up by plants.

•Human Impacts on the Phosphorus Cycle: • The phosphate is obtained through mining of certain deposits of calcium phosphate called apatite. Huge quantities of sulfuric acid are used in the conversion of the phosphate rock into a fertilizer products.• Run off is a major concern as animal waste fertilizer may collect in lakes.• Human sewage also causes problems as Phosphorus is only removed if there are tertiary treatments involved.

Recap!

• Remember, Energy Flows as Nutrients Cycle!