ECOLOGICAL PYRAMID, ENERGY AND BIOLOGICAL MAGNIFICATION NOTES

ENERGY 1. Kinetic Energy – moving energy The ability to do work & transfer heat Some Different Forms of Energy: 1. Kinetic Energy – moving energy 2. Heat – kinetic energy of molecules & atoms 3. Electricity – movement of charged particles 4. Chemical Energy – energy stored in bonds of molecules 5. Gravitational Potential Energy – energy stored by an object that can fall

All energy used in biological systems originally comes from the sun The amount of energy gained by producers is defined as 100% of the energy available to biological systems and is stored as chemical energy

Law of Conservation of Energy Energy cannot be created or destroyed!! When a consumer eats a producer, the chemical bonds in the producer’s molecules are broken and new molecules are made in the consumer which releases energy (this is the energy used by the consumer)

So mass is also conserved – Law of Conservation of Mass In no part of the food chain process is any matter destroyed (no atoms disappear) So mass is also conserved – Law of Conservation of Mass Mass can be neither created or destroyed

BIOMASS Total mass (amount of living tissue) of all the organisms within a given trophic level

Only a small fraction of the biomass from one trophic level moves to the next 2 Reasons for this: Many organisms are not consumed by organisms at the next trophic level – energy is not available for transfer Some of the biomass at each level consists of materials consumers won’t eat – bones, teeth, beaks, claws, shells, wood

ECOLOGICAL PYRAMID Shows the relationships between producers and consumers at the trophic levels in an ecosystem Grass, flowers Rabbits, mice Snakes Owls

WHY A PYRAMID SHAPE? In most food chains fewer organisms occupy each higher trophic level (lots of producers, many primary consumers, fewer secondary consumers and very few tertiary consumers)

Energy in a Trophic Pyramid The energy the producers gained from the sun has 2 directions it can go: 1. up to the next trophic level 2. released as heat 10% of the energy is consumed by the next trophic level and the rest (90%) is released into the environment as heat Notice this adds up to 100% because of the Law of Conservation of Energy

Energy in a Trophic Pyramid, cont. The same is true for primary consumers – the energy that primary consumers gained from the producers has 2 directions it can go: 1. up to the next trophic level 2. released as heat 10% goes to the next trophic level and 90% is released as heat, which again adds up to 100%, keeping in line with the Law of Conservation of Energy

10 PERCENT LAW Energy available at each trophic level is about 1/10 the energy available from the level below producers 1st consumers 2nd consumers 3rd consumers .1% 20 1% 200 2,000 10% 100% 20,000

Heat As said earlier, much of the energy from one level to the other on a pyramid is released as heat Heat can move from one place to another in only 3 ways: 1. Conduction 2. Convection 3. Radiation

Heat, cont. Conduction – when two objects come into physical contact and heat is transferred (ex. Touching the stove) Convection – when heat moves through a fluid (liquid or gas) because hot fluids rise and cold fluids sink (ex. Holding your hand above the stove and getting hot) Radiation – when heat is transferred by electromagnetic energy (like light and infrared); the radiation causes the molecules to start moving (ex. You get hot while outside because the sun’s radiation heats you up)

BIOLOGICAL MAGNIFICATION The buildup of a pollutant in organisms at higher tropic levels in a food chain The concentration of a pollutant (like DDT) multiplies as it passes up the food chain from producers to consumers, so the amount of DDT in top-level consumers can be magnified nearly 10 million times