Unit 1: Ecosystem Sustainability

Wolf Island

1.1 Capturing Energy from the Sun

Definitions Ecosystem - all the living (biotic) and

non-living (abiotic) parts in an environment that interact.

Trophic levels - feeding levels.

Food Chains

Food Chains

Grass grasshopper frog wolf

Plants Herbivore Carnivore Top

Carnivore

Producer Primary Secondary Tertiary Consumer Consumer Consumer

1st 2nd 3rd 4th

Trophic Trophic Trophic Trophic Level Level Level Level

Show the patterns of energy movement through an ecosystem.

All energy for life is powered by the Sun.

Producers convert solar energy into chemical energy for

the food chain.

(don’t eat other organisms – some exceptions)

All energy needed by consumers must be made by producers by photosynthesis.

CO2 + H20 CHO + O2 (Cycle of Life)

Solar Energy

Used for life processes.

AssignmentAssignment Read p4 – 7Read p4 – 7 Stretch Stretch

Your Mind Your Mind P 5P 5

pg 7 #1 – 6pg 7 #1 – 6

Why does energy decrease as you up the trophic levels? (gr 7?)

1.2 Feeding Levels

Scavengers – animals that eat large dead animals. (gr 7)

Detrivores – small creatures that eat small dead animals, plants and dung. (Eg. crabs, earthworms, maggots, some ants.)

Decomposers

a type of detrivore that eats the last small amount of the dead material. (includes bacteria and fungi.) (gr 7)

Food Chains based on the Dead

Eg) grass cows (dung) beetles garter

snake owl

food chains with abiotic elements outnumber those without.

Pyramid of Numbers

usually the number of organisms decrease up trophic levels. Amount of energy decreases as you go up

each level 1st level has the most energy

draw pyramid on pg 14.

Reversed Pyramid of Numbers

Most animals/carnivores are larger than the prey they eat - exceptions

a single LARGE producer (tree) may provide food for many insects

draw pyramid on pg 15.

Pyramid of Biomass

Def’n. Biomass (the amount of mass of living material) Biomass more accurately tells the amount of

producer material supporting higher trophic levels than numbers do.

Why doesn’t the ocean system collapse? Phytoplankton reproduce faster than zooplankton can

eat them Zooplankton reproduce faster than fish can eat them

Draw diagram on p 16

Inverted Pyramid of Biomass

Occurs only when the producers reproduce REALLY fast. Eg) a few phytoplankton can be enough

food to support the much heavier zooplankton.

Draw diagram on p 16

Pyramid of Energy Flow

Most Energy Least Energy producers 1°consumers 2°consumers

3°consumers Usually about 10% of the energy goes to the next

level. (the rest used for life processes) Chains are rarely more than 4 links long.

Draw diagram on p 17

World Food SupplyEating Grain rather than Meat

World agriculture is trying to shorten food chains. Why?

See BLM 1-14

Pyramid of Energy Flow

Assignment Copy diagrams on p 14-17 BLM 1-1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-9, 1-11,

1-12, & 1-14 Read pg 8 – 17 & do pg 17 #1 - 5

1.3 Populations

Populations – groups of individuals of the same species. Killer Whales p 18

Carrying Capacity – the largest population of a species that an environment can support.

Observe How Populations influence each other in a food web.

Carrying Capacity

Carrying Capacity is affected by:

1. higher trophic level: number of predators

2. lower trophic level: amount of food available

- Fox and rabbit cycle

Carrying Capacity is affected by:

3. availability of materials and energy: water, essential materials

4. competition: when populations grow individuals must compete with each other for food, mates, water, shade, etc.

Carrying Capacity (cont’d)

Competition

intraspecific competition – occurs within the same species.

interspecific competition – occurs between 2 different species with the same needs. Eg) wolves, pumas, coyotes compete for deer.

The number of individuals that can live in an area at one time.

some animals need more room than others.

crowding causes:

1. aggression

2. neglect of young

3. spread of disease or parasites

Population Density

Since items 1 – 3 depend on how crowded the animals are they are density-dependent factors. These increase in significance as the

population increases

density-independent factors don’t depend on population but affect population anyway. Eg) floods, droughts, or fires.

Density-dependent

Assignment

Read p 18-24 Do CYU pg 24 #1-6 BLM 1-17

Bioaccumulation

The tendency of pollutants to become more concentrated as you move up the food chain (trophic levels).

The pollution often damages or kills the organism because it is often poisonous.

Steps:

1. Plants work hard to take in nutrients and water (containing pollution) and use or store them. Pollution is stored accidentally and becomes concentrated.

2. Since most energy is lost between trophic levels, herbivores must eat a LOT of plants. The pollution is usually stored in the fats of the herbivores.

Steps (cont’d)

3. If the herbivore is caught and eaten, its fat is digested and the pollutant moves to the fat of the new consumer. The consumer must eat many herbivores in order to survive.

Example: Grass sprayed with chemical Mouse eats eats grass Hawk eats mouse

The DDT Story – Read pg 30-31 and do pg 32# 1-11

Read pg 25-34 and do pg 34 1-6

The DDT Story

1. DDT is sprayed on plants, they absorb it and it becomes part of their structure.

2. The organisms with the most DDT are dolphins with 5200 ppb.

The DDT Story

3. The dolphins are in the 3rd/4th trophic level.

4. The higher an organism is in the food chain, the more concentrated the DDT will be in its body.

5. The DDT is 430,000 times greater in the fish than in the seawater (43/0.0001) and 52 M times (5200/0.0001) greater in the dolphins.

The DDT Story

6. Animals at the top of the food chain are at a much greater risk because they are consuming prey that have high concentrations of the poisons in their tissues from eating contaminated organisms.

The DDT Story

7. DDT can affect organisms far away from the source because of:

a) Migration (migratory birds)

b) Large range (hawks)

The DDT Story

8. All organisms have a certain amount of permanent body fat. Because DDT doesn’t break down it eventually affects the organisms DNA. Affected cells may become cancerous. Desirable characteristics would be:

a) Water soluble

b) Shorter shelf life

c) Affected only the target pest

The DDT Story

8. DDT could have killed an insects competitors so its population could grow unchecked.

The DDT Story

11. Answers are:

a) Seabirds over the Bay of Fundy have higher levels of DDT. Reasons include:

Atlantic ocean is further from agricultural areas Seabirds food higher concentrations in B of F

b) Pesticide levels seem to have decreased between the late 60’s and early 80’s. DDT was banned in 1969.

c) Different level of body fat. Feed on larger prey

The DDT Story

In order for a pollutant to bioaccumulate it must be:

1. Long-lived.

2. Concentrated by the producers.

3. Fat-soluble.

Make notes on the harmful effects of the

following toxins: DDT Lead Dioxin PCB’s Mercury

DDT

Used to control mosquitoes and lice in the 50’s.

Not absorbed readily by human skin. Controversy over effect on humans Stays in human fat, especially breast

milk. Thinned eagle (birds of prey) egg shells Should it still be used today?

Lead

Roman aquaducts Historically found in gasoline, house

paint, pesticides, solder, fish wts., & ammunition

Anemia, N.S. damage, kidney damage, etc.

Most serious in pregnant women (miscarriage/stillbirth) and young children (more easily absorbed)

Dioxin

One of the most toxic chemicals Industrial by-product involving Cl

compounds. (paper bleaching, agent orange, etc.); Love Canal, ON

Incinerating chlorinated wastes Carcinogen (causes cancer) Reproductive & developmental problems,

Immune system damage, regulatory hormone interference

Source - fish

PCB’s

Non-flammable, chemical stability, high boiling point, & electrical insulating properties – very useful

Light ballasts Carcinogens, immune system, rep’ve

system, NS, etc.

Mercury

Ingested, inhaled or absorbed through skin

CNS and kidney damage Memory loss, hallucinations, tremors Pregnant women and children at greater

risk Fish is major source

Let Them Eat Cake

Free writing exercise. How did you feel when you saw how

much other groups got? How did you divide the cake within your

group? Did you do anything to get more cake, or

give any away?