Ecology: The Study of Ecosystems

Organization of Life AKA Biological Organization

Ecosystem The interaction between organisms and their environment The interaction of abiotic and biotic factors Can be small (pond, rotting log, local forest, our school) or large (Biomes like tundra, desert, savannah, etc. are super large ecosystems).

Biotic vs. Abiotic Factors Biotic factors: factors that are or came from a living thing. Examples: plants, bacteria, fungi, animals, fish, birds, insects, leaves, skin, animal waste Abiotic factors: factors created by non-living things. Examples: sunlight, temperature, weather factors, elevation, air, chemicals, minerals, rocks, roads

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Trophic Levels (Feeding Levels) Producers – Also known as Autotrophs – Make their own food, mostly by photosynthesis. – Most autotrophs are green plants, but some are microorganisms like bacteria. – They convert the suns energy into chemical energy. – They are the First Trophic Level.

Trophic Levels Consumers – Also called Heterotrophs – Cannot make their own food – Must consume another living thing to get energy – Can be animals, fungi or bacteria – Even a few plants are considered consumers….the venus fly trap plant “eats” insects

Types of Consumers Herbivore – animal that eats plants (ex. deer) Carnivore – animal that eats animals (ex. lion) Omnivore – animal that eats both plants and animals Detritivore – animal that eats dead organisms or their wastes (detritis). They are also called scavengers (ex. vulture) Decomposer/Saprotroph – break down dead organisms/animal wastes and return/recycle nutrients to the ecosystem Ex. Fungi, Bacteria, or Detritivores A type of consumer

Some other terms to know Nutrients: Substances that are required by an organism for its normal functioning, growth and repair. Nutrients include fats, carbohydrates, proteins, vitamins, minerals and water as well as the elements that they are composed of. Organic: matter that contains the element carbon. All living things contain this element and therefore living things are organic matter. Inorganic: matter that does not contain the element carbon. For example, water does not contain carbon atoms and is therefore an inorganic substance. (H 2 0)

Food Chains A linear sequence of who eats who in an ecosystem

1st 2nd 3rd 4th Top Carnivore

Predator Prey The tip of the arrow points towards the thing doing the eating

Food Webs Interconnected food chains showing who eats who

Video Watch Bill Nye’s “Food Webs” and answer the questions on the worksheet (just first 13 min) 2laAJl0&safe=active

Energy in Ecosystems Ultimately, the source of all energy in ecosystems is the sun Producers convert the sun’s energy to food energy Consumers eat plants or they eat animals that ate plants

Energy Flow in Ecosystems Energy flow is one way – from the sun to plants to animals The energy used by living organisms is either used up for their life activities or it is lost along the way as heat Energy does not cycle (lost energy or heat from ecosystems does not return to the sun)

The Cow eats grass. Some of the energy from grass goes into making new cow tissue, but lots of the energy (90%) is lost as heat, during respiration or as urine and feces Grass

Thermodynamics Definition – the study of how energy is transferred 1 st Law – energy is conserved; it is not created or destroyed 2 nd Law – every time there is an energy transfer, some energy is lost along the way

Ecological Pyramids Used to show the energy available at each trophic level There are 3 types: – Pyramid of Energy – Pyramid of Biomass – Pyramid of Numbers

Ecological Pyramids

Energy Pyramids Energy in Joules or Kilocalories shown at each level

Pyramid of Energy Only 10% of the energy from a trophic level is available to the next trophic level – called the 10% rule

Pyramid of Biomass Shows the dry weight of organisms at each level

Pyramid of Numbers Shows actual counts of numbers of organisms

A Pyramid of Numbers may not give a great picture of what is going on….

Why Food Chains aren’t longer The 90% loss of energy at each trophic level explains why there can’t be more than 5 trophic levels. By the time quaternary consumers get to eat, there just isn’t much energy left.

Eat Low on the Food Chain Find out! Equals BONUS Marks

Ecological Pyramids Worksheet Complete the worksheet for homework Due next class

Worksheet Answers 1)Decreases 2)10% 3)Heat, Respiration, Wastes 4)2nd 5)Energy emitted from the sun never returns back to the sun 6)Dry weight/mass of living things 7)Biomass = dry mass; Numbers = actual counts

8) Because there is a 90% loss of energy/biomass at each step, so by the time tertiary or quaternary consumers get to eat, there isnt much food left 9) There has to be more herbivores than carnivores because there has to be more energy at the trophic level that is being fed on than in the one doing the eating because of how much energy is lost between levels. 10) The trophic level above always has less energy compared to the one below it.

11) Producer Grass Primary Consumer Grasshopper Secondary Consumer Chicken Tertiary Consumer Hawk

BONUS QUESTION Ecologically friendly - More food to feed more people (10 x more). Human population is increasing so need enough food for all. Less land is needed to raising plants compared to raising animals. Healthier – less toxins(less biomagnification) and less bad fats from meat. 1 Human 10 Chickens 100 Corn 10 Humans 100 Corn