Food Chains, Food Webs, and the Transfer of Energy Unit 2: Ecosystems Food Chains, Food Webs, and the Transfer of Energy

The study of the interactions between organisms and their environment. ECOLOGY The study of the interactions between organisms and their environment.

The Nature of Ecology Ecosystem organization Organisms Populations Communities Ecosystems Biosphere

The Earth’s Life-Support Systems Troposphere Stratosphere Hydrosphere Lithosphere Biosphere

Sustaining Life of Earth One-way Flow of energy Cycling of matter

Ecosystem Services and Sustainability

ENVIRONMENT = all the factors that affect an organism. ABIOTIC FACTOR = non-living factors in an environment. BIOTIC FACTORS = living factors in an environment.

HABITAT = place where an organism or population of organisms live. NICHE = the role or job of a species in an ecosystem.

Biosphere Ecosystems Communities Populations Organisms

ECOSYSTEM includes all the biotic & abiotic factors in an environment.

Autotrophs A groups of organisms that can use the energy in sunlight to convert water and carbon dioxide into Glucose (food) Autotrophs are also called Producers because they produce all of the food that heterotrophs use Without autotrophs, there would be no life on this planet Ex. Plants and Algae

Autotrophs

Autotrophs Chemotrophs Autotrophs that get their energy from inorganic substances, such as salt Live deep down in the ocean where there is no sunlight Ex. Bacteria and Deep Sea Worms

Heterotrophs Organisms that do not make their own food Another term for Heterotroph is consumer because they consume other organisms in order to live Ex. Rabbits, Deer, Mushrooms

Heterotrophs

Heterotrophs Consumers 1. Scavengers/Detritivores – feed on the tissue of dead organisms (both plans and animals) Ex. – Vultures, Crows, and Shrimp

Heterotrophs Consumers 2. Herbivores – eat ONLY plants Ex. – Cows, Elephants, Giraffes

Heterotrophs Consumers 3. Carnivores – eat ONLY meat Ex. – Lions, Tigers, Sharks

Heterotrophs Consumers 4. Omnivores – eat BOTH plants and animals Ex. – Bears and Humans

Heterotrophs Consumers 5. Decomposers – absorb any dead material and break it down into simple nutrients or fertilizers Ex. – Bacteria and Mushrooms

Transfer of Energy When a zebra eats the grass, it does not obtain all of the energy the grass has (much of it is not eaten) When a lion eats a zebra, it does not get all of the energy from the zebra (much of it is lost as heat)

Transfer of Energy The two (2) previous examples of energy transfer show that no organism EVER receives all of the energy from the organism they just ate Only 10% of the energy from one trophic level is transferred to the next – this is called the 10% law

Trophic Levels Energy moves from one organisms to another when it is eaten Each step in this transfer of energy is know as a trophic level The main trophic levels are producers, consumers, and decomposers

Food Chains The energy flow from one trophic level to the other is know as a food chain A food chain is simple and direct It involves one organism at each trophic level Primary Consumers – eat autotrophs (producers) Secondary Consumers – eat the primary consumers Tertiary Consumers – eat the secondary consumers Decomposers – bacteria and fungi that break down dead organisms and recycle the material back into the environment

FOOD CHAIN = used to show how matter & energy move through an ecosystem.

Food Chain

Ocean Ecosystem Structure Trophic levels and dynamics

ENERGY

How about Mass Transfer?

Food Web Most organisms eat more the JUST one organism When more organism are involved it is know as a FOOD WEB Food webs are more complex and involve lots of organisms

FOOD WEB = shows all the possible food chains in an ecosystem

Food Web Notice that the direction the arrow points  the arrow points in the direction of the energy transfer, NOT “what ate what”

Food Web

Working at Little Rock Lake in Wisconsin, researchers tracked the connections in the food web-predators like the smallmouth bass at the top and tiny free-floating plants (phytoplankton) at the bottom. (BBC NEWS)

Ecological Pyramid An ecological pyramid shows the relationship between consumers and producers at different trophic levels in an ecosystem Shows the relative amounts of energy or matter contained at each trophic level The Pyramid shows which level has the most energy and the highest number of organisms

ECOLOGICAL PYRAMIDS Are graphical models of the quantitative differences that exist between the trophic levels of a single ecosystem. In accordance to the 2nd Law of Thermodynamics, there is a tendency for numbers and quantities to biomass and energy to decrease along food chains, therefore the pyramids become narrower toward the top.

Ecological Pyramid

Ecological Pyramid

Ecological Pyramid Which level has the most energy? Which level has the most organisms? Which level has the least organisms? Which level has the least energy?

A few large producers (the trees) support a much larger number of Grassland (summer) Temperate Forest Producers Primary consumers Secondary consumers Tertiary consumers A few large producers (the trees) support a much larger number of Small primary consumers (insects) that feed on the trees.

Biomass The total mass of the organic matter at each trophic level is called biomass Biomass is just another term for potential energy – energy that is to be eaten and used. The transfer of energy from one level to another is very inefficient (10% Law)

Biomass

PYRAMID OF BIOMASS represent the standing stock at each trophic level. Units: J m-2 or g m-2

Abandoned Field Ocean Tertiary consumers Secondary consumers Primary consumers Producers In open waters of aquatic ecosystems, the biomass primary consumers (zooplankton) can exceed that of producers. The zooplankton eat the Producers (phytoplankton) as fast as they reproduce, so their population is never very large.

PYRAMID OF PRODUCTIVITY represents the flow of energy through each trophic level. Units: J m-2 yr-1 or g m-2 yr-1

As you move up each trophic level, only 10% of the energy is transferred. The other 90% is used for everyday life functions, metabolism.

Pyramid structure affects the functioning of an ecosystem. Bioaccumulation

Symbiosis A close and permanent association between organisms of different species Commensalism – a relationship in which one organism benefits and the other is not affected Example: Barnacles on a whale Mutualism – a relationship in which both organisms benefit from each other Example: Birds eating pest off a rhino’s back Parasitism – A relationship in which one organism benefits and the other is harmed Example: Ticks on a dog

Ecological Succession A change in the community in which new populations of organisms gradually replace existing ones 1. Primary Succession – occurs in an area where there is no existing communities and for some reason (s) a new community of organisms move into the area

Ecological Succession A change in the community in which new populations of organisms gradually replace existing ones 2. Secondary Succession – occurs in an area where an existing community is partially damaged

Ecological Succession A change in the community in which new populations of organisms gradually replace existing ones 3. Climax Community – a community that is stable and has a great diversity of organisms