Understanding Ecosystems

Grade 9 Science

Sustainable ecosystems

Big Ideas:• Ecosystems are dynamic and have the ability

to respond to change, within limits, while maintaining their ecological balance.

• People have the responsibility to regulate their impact on the sustainability of ecosystems in order to preserve them for future generations.

Looking Ahead

Unit Task Preview:Ontario’s Species of Concern

• You will select TWO contrasting species that are of concern in Ontario. You will choose one NATIVE species that is at risk and one species that is non-native and INVASIVE.

• For each species you will investigate

• The factors that have led to their current status.

• How these factors are influencing species and the health of the ecosystem they live in.

• Implications related to human interests.• Actions that could change the species status.

Key Question: How are organisms influenced by their living and non-living environment?

Unit BSustainable Ecosystems

Chapter 2Understanding

Ecosystems

Chapter 3 Natural

Ecosystems and stewardship

Chapter 4Ecosystems by

Design

Key Concepts

Life on Earth exists in the atmosphere, lithosphere and

hydrosphere

Photosynthesis and cellular respiration are

complimentary processes in an

ecosystem

Energy passes through ecosystems, whereas matter cycles within

ecosystems

Human activities influence

biogeochemical cycles such as the water and

carbon cycles

Ecosystems are composed of biotic and

abiotic components

Terrestrial biomes and aquatic ecosystems are largely determined by

their abiotic characteristics.

It’s All Greek to me....

• Lithos - means stone• Atmos – means vapour• Hydro - means water• Bio – means life• Sphere - means ball

Life on Planet Earth

• Terms to Know:• Atmosphere – layer of gases surrounding the

Earth.• Lithosphere – Earth’s solid outer layer• Hydrosphere – all of Earth’s water in solid,

liquid or gas form• Biosphere – the zone around Earth where life

can exist.

What is it? A layer of gases surrounding the Earth

What is it made of? Nitrogen, carbon dioxide, oxygen, water vapour, other gases.

What does it hold in? Thermal energy (heat)

What does it block out? U-V light.

The Atmosphere

Lithosphere, Biosphere, Atmosphere, Hydrosphere

• Plants (biosphere) require minerals (lithosphere), water (hydrosphere) and carbon dioxide (atmosphere) to grow.

• Think of another example related to the movie red crabs crazy yellow ants.

The Gaia Hypothesis

• In 1960 James Lovelock advanced the Gaia hypothesis. He proposed that Earth through the interactions among the biosphere, lithosphere, atmosphere and hydrosphere behaving like a living organism. He proposed that the Earth is capable of responding to changes in its environment and maintaining relatively consistent internal conditions over a long period of time – just like a living cell.

Scale Model of Planet Earth.

11.8mm

Wrong = 11.8mm

108.66

1.57

0.13

EcosystemComposed of populations of plant and animal species, abiotic and biotic environments

Word Associations

Abiotic & Biotic Factors

• Abiotic – means non living such as –Air–Temperature–Rock–Water–Minerals

• Biotic all living organisms their remains and their waste.• Plants• Animals• Bacteria

Symbiosis: the interaction between members of two different species that live in close association.Fungi receive shade and nutrition from the trees, mushrooms help the trees absorb water.

Predation: when one organism consumes another organism for food. The organism that is consumed is called prey. The one that eats the prey is called a predator. The relationship between predator and prey can influence the population of both the predator and the prey and affect the whole ecosystem in which they live .

Competition occurs when two or more organisms compete for the same resource such as food, space, light.

Energy Flow in Ecosystems

• All energy on Earth comes from the Sun• Plants use solar energy to turn carbon dioxide

and water into sugar. They need the green chlorophyll in their leaves to help them do this. This process is called PHOTOSYNTHESIS.

• It means making food (synthesis) from light (photo).

Photosynthesis vs. Respiration

• Photosynthesis: Green plants• Uses light energy from the sun, Carbon

Dioxide and water• Makes sugar and oxygen.

• Respiration: All living things• Uses food (sugar) and Oxygen• Makes Carbon dioxide and water, releases

energy

CO2 = Carbon dioxide, H2O = water, O2 = oxygen

2009 Carbon dioxide concentration in the troposphere.

"Present day" (1990s) sea surface dissolved inorganic carbon concentration (from the GLODAP climatology

Producers

• Because plants can use the energy from the Sun to make food they are called Producers.

• Producers form the first link in all the food chains.

254.3 25..43 2.543

Consumers

• Animals eat plants or eat animals that eat plants. They are called Consumers.

• Herbivores are consumers that eat plants• Carnivores: are consumers that eat herbivores.• Omnivores: Eat both plant and animal materials• Scavengers: are consumers that eat dead remains• Parasites: are consumers that feed on living

organisms.

Each step in the food chain is known as a TROPHIC level.Plants are called Autotrophs – they make their own food.Animals are called Heterotrophs – they consume food made by plants.

Algae 100%

Australian Blackfish10%

Trout 1%

Fisher-man0.1%

Sun energy

Primary Producers

plants

Primary Consumersherbivores

Secondary Consumerscarnivores

Tertiary Consumers

Top carnivores

First trophic level

Second trophic level

Third trophic level

Fourth trophic level

Decomposers

Sun

Berries, flowers, grasses & seeds

Butterfly, Marmot , Deer, Grouse, Chipmunk

Bear, Red tailed Hawk

Decomposers

Food Web Great Lakes

Eutrophication• Eutrophication (also known as nutrient enrichment)

is a result of large amounts of nutrients being released into a nutrient deficient water body which leads to excessive amounts of aquatic plant growth.

• Eutrophication can be accelerated by the release of nutrients from human activities such as from fertilizers used in agriculture and at our homes. This rapid transition is not beneficial for the fish and other organisms which live in lakes who have to cope with depleted oxygen levels because of the decomposition of plants,

Eutrophication in the Sea of Azov. (Source: NASA).

What can Eutrophication Do?

Deformed frogs have been linked to an increase in phosphates and Nitrates

Ramshorn Snail

Bioaccumulation• Bioaccumulation refers

to how pollutants enter a food chain

• increase in concentration of a pollutant from the environment to the first organism in a food chain

Biomagnification

• biomagnification refers to the tendency of pollutants to concentrate as they move from one trophic level to the next.

• increase in concentration of a pollutant from one link in a food chain to another

Why is this important?

• Means that even small concentrations of chemicals in the environment can find their way into organisms in high enough dosages to cause problems. In order for biomagnification to occur, the pollutant must be:

• long-lived • mobile • soluble in fats • biologically active

• If a pollutant is short-lived, it will be broken down before it can become dangerous.

• If it is not mobile, it will stay in one place and is unlikely to be taken up by organisms.

• If the pollutant is soluble in water it will be excreted by the organism.

• Pollutants that dissolve in fats, however, may be retained for a long time.

What did DDT do?

•Caused the top predatory birds such as Eagles, Hawks, Falcons, Gulls to lay eggs with thin shells.•Led to loss of successful breeding.•Numbers of these species declined.

What does PCB’s do?

• Polychlorinated biphenyls (PCBs) are a group of manmade chemicals. They are oily liquids or solids, clear to yellow in color, with no smell or taste.

How do PCBs get into the environment?

• PCBs have been released into the environment through spills, leaks from electrical and other equipment, and improper disposal and storage. It is estimated that more than half of the PCBs produced have been released into the environment.

• Once in the environment, PCBs can be transported long distances and they bind strongly to soil and sediment so they tend to be persistent in the environment. They have been found in air, water, soil, and sediments throughout the world. Because PCBs have not been made since 1977, the levels in the environment and in the food chain have been declining.

• Most people are exposed to PCBs by eating contaminated fish, meat, and dairy products. Catfish, buffalo fish, and carp usually have the highest PCB levels.

• Plants take up only small amounts of PCBs from the soil, so amounts in grazing animals and dairy products are generally lower than in fish.

• Dust contaminated with very small levels of PCBs may be found on the outer surfaces of fruits and vegetables

• Birth defects have been linked to mothers who have been exposed to PCBs.

• Developing fetuses and young children are the most vulnerable to PCBs, therefore, children and women who may become pregnant, are pregnant, or nursing should limit their exposure to PCBs.

• A pregnant woman can pass these chemicals to her unborn child.

• Mothers who eat highly contaminated fish before giving birth may have children who have slower mental development.

• PCBs also can be passed to a baby through breast milk. However, the significant benefits of breastfeeding far outweigh the risks. Young children also may experience developmental health effects.

Mercury• Mercury compounds can be toxic at low levels in the

environment. The characteristics of mercury that make it a health and environmental problem are its toxicity and persistence in the environment, and its ability to accumulate and bioconcentrate as methyl mercury in fish and fish-eating predators such as large fish or loons.

• Mercury also moves over long distances on air currents and can be deposited on land and in rivers, lakes and oceans far from the source of release, therefore spreading the potential exposure to many more people.

Minamata