2.1 Ecosystem Structure

Ecosystems Have Living and Nonliving Components

• Abiotic – Non-living• Water• Air• Nutrients• Rocks• Heat• Solar energy

• Biotic- Living • Any living or once living

Major Biotic and Abiotic Components of an Ecosystem

Fig. 3-6, p. 59

Ecologists Study Interactions in Nature• Ecology: Study of how organisms interact with each other and

their environment• Species- A particular type of organism• Populations- A group of individuals of the same species living

in the same place• Communities-Populations of different species living in the

same place, and potentially interacting with each other• Ecosystems-A community of different species interacting with

one another and with their nonliving environment of matter and energy

• Habitat-An environment where a species lives• Niche- How an organism makes a living (role/job)

Smallest unit of a chemical element that exhibits its chemical properties

Atom

Molecule Chemical combination of two or more atoms of the same or different elements

CellThe fundamental structural and functional unit of life

Organism An individual living being

Population A group of individuals of the same species living in a particular place

Community Populations of different species living in a particular place, and potentially interacting with each other

Stepped Art

Ecosystem A community of different species interacting with one another and with their nonliving environment of matter and energy

Biosphere Parts of the earth's air, water, and soil where life is found

OxygenHydrogen

Water

Fig. 3-5, p. 58

Food Chain vs. Food Web

• Food Chain – shows flow of energy from one organism to another

Food Chain vs. Food Web• Food web- shows flow of energy interconnected to many organisms (all possible

food chains)

Lake Michigan Food Web

Trophic Levels

• Trophic Level = feeding level (position of an organism on a food chain)

Producers and Consumers• Producers- (autotrophs “self-feeders”)--Plants• Perform Photosynthesis:• Use sun energy to make their own food• Waste product is oxygen

• Consumers- (heterotrophs “other feeders”) – Organisms that obtain nutrients from living things• Primary consumers = Herbivore (eats plants)• Secondary consumers – omnivores (eats both plants

and animals) primary consumers and producers• Tertiary consumers- Carnivores(eat meat) other

consumers

Producers

Fig. 3-7a, p. 59

Consumers

Fig. 3-8a, p. 60

Producers and Consumers Are the Living Components of Ecosystems (2)

• Decomposers• Consumers that release nutrients• Ex. Bacteria, Fungi

• Detritivores (scavenger) • Feed on dead bodies of other organisms• Ex. Earthworms, Vultures

Decomposer

Fig. 3-9a, p. 61

Detritivores and Decomposers

Fig. 3-10, p. 61

2.1.4 Ecological Pyramids

• Pyramids show differences that exist between trophic levels

• Always a decrease of energy and biomass when moving up a pyramid

• Only ~10% of the energy from the one level is passed to the next level

• ~90% of energy is used released as heat (respiration)• Three types of pyramids (biomass, numbers, energy)

Pyramid of Biomass• Biomass (g m -2)• Dry weight of all organic matter of a given trophic level in a

food chain or food web

Pyramid of Energy

• Pyramid of energy flow (J m-2 yr-1)• Less chemical energy for higher trophic levels

Pyramid of Numbers• Pyramid of numbers• Shows the total number of organisms at each trophic level• Snapshot in time

Pyramid structure

• Bioaccumulation- concentration of toxins increases in an individual organism’s tissues

• Biomagnification- concentration of toxins increases as the trophic level increases

Biomagnification of DDT

What is DDT?

• Dichlorodiphenyltrichloroethane…that’s why we call it DDT!!

• Insecticide used to fight malaria • Started in 1948 to kill mosquitoes and fight spread of

malaria• Stored in the fats of organisms, and biomagnifies

through the food chain• Predatory bird populations suffered• Banned in the US in 1972

2.1.7 Population InteractionsCompetition (- / -)

• Competition – Two or more organisms in the same community seek the same resource at the same time.

• Two types• Interspecific – between two different species • Intraspecific- within an individual species

• Resources must be in limited supply (food, water, light, shelter, space, mates)

• Mountain goat competition for mates

Inter or intra???

Predation ( + / -)

• Predation- One species killing another and consuming it in the process

• Lions prey on wildebeests in Africa

Herbivory (+/-)

• Herbivory- consumption (grazing) of producers by primary consumers

• Caterpillar eating leaf

Parasitism (+/-)

• Parasitism – Organism that lives on or in another host organism

• Parasite benefits and host is harmed• Tapeworm in human intestine

Mutualism (+/+)

• Mutualism- both organisms benefit from interactions• Best example is Lichen• Lichen is algae and a fungus• Fungus provides structure and algae provides food

source

Commensalism (+ / 0)

• Commensalism – One organism benefits and the other organism is not affected

• Clownfish and the sea anemone

Ammensalism (- / 0 )

• One species is harmed and another species is not affected.• Ex. Algae blooms can lead to the death of many species of fish, however the algae do not

benefit from the deaths of these individuals.

Neutralism (0 / 0)

• Two organisms do not affect each other• Essentially they have no relationship• Dandelions and salmon in a ecosystem (have little or

no effect on each other

Big Ideas

1. Some organisms produce the nutrients they need, others survive by consuming other organisms, and some recycle nutrients back to producer organisms.

2. Human activities are altering the flow of energy through food chains and webs and the cycling of nutrients within ecosystems and the biosphere.