ENERGY FLOW IN ECOSYSTEMS

SCIENCE 1206

TOPICS LIST

ENERGY FROM THE SUN PERCENTAGES

ALBEDO EFFECT

PHOTOSYNTHESIS and CELLULAR RESPIRATION

THERMODYNAMICS

PYRAMIDS PYRAMID OF ENERGY

PYRAMID OF BIOMASS

PYRAMID OF NUMBERS

ROLES IN ECOSYSTEMS KEYSTONE SPECIES

ECOLOGICAL NICHE

INTRASPECIFIC VS. INTERSPECIFIC COMPETITION

EXOTIC SPECIES

Where Does our Energy Come From?

The SUN is the source of energy for the vast

majority of life on Earth.

Observe the following diagram:

ENERGY FROM

THE SUN

What happens to the majority of the Sun’s energy?

It heats the atmosphere, earth’s surface, and water.

PERCENTAGES:

_______ % is reflected by Clouds and Earth’s Surface

_______ % warms the atmosphere, land, and

hydrosphere

_______ % generates wind patterns

_______ % is used in the process of photosynthesis

ALBEDO EFFECT

A measure of the AMOUNT of sunlight REFLECTED from an object.

Expressed as a decimal value

Example: 27 % reflection by clouds is 0.27

What are examples of objects that REFLECT sunlight?

In general, LIGHT-COLOURED objects such as:

___________________________________________

These highly reflective objects have a HIGH ALBEDO.

What are examples of objects that ABSORB sunlight?

In general, DARK-COLOURED objects such as:

____________________________________________

These light-absorbing objects have a LOW ALBEDO.

Also, GREENHOUSE GASES have a low albedo.

ALBEDO EFFECT

PHOTOSYNTHESIS

What is it?

A biochemical process whereby PRODUCERS use the Sun’s energy, carbon dioxide, and water to produce sugar and oxygen.

GENERAL CHEMICAL EQUATION:

6 CO2 + 6 H2O + Sun’s Energy C6H12O6 + 6 O2

CO2 is carbon dioxide C6H12O6 is glucose (sugar)

H2O is water O2 is oxygen

Oxygen is necessary for CONSUMERS.

Sugars are necessary as a usable form of energy for nearly ALL LIFE on EARTH.

CELLULAR RESPIRATION

What is it?

A biochemical process whereby CONSUMERS release the

energy stored in the sugar they ingest.

By eating sugars and breathing in oxygen, consumers produce

carbon dioxide, water, and energy for life processes.

GENERAL CHEMICAL EQUATION:

C6H12O6 + 6 O2 6 CO2 + 6 H2O + Energy

Cellular respiration is the OPPOSITE reaction to Photosynthesis

What kinds of life processes?

HOMEWORK

Page 33

Numbers 4 a), c), d)

THERMODYNAMICS

What is THERMODYNAMICS?

The study of ENERGY TRANSFORMATIONS from one form to another (ex: chemical energy to heat energy)

2 Thermodynamic LAWS that apply to ecosystems are:

FIRST LAW OF THERMODYNAMICS

Energy CANNOT be CREATED NOR DESTROYED, only TRANSFERRED FROM ONE FORM TO ANOTHER.

SECOND LAW OF THERMODYNAMICS

During energy transfers, SOME ENERGY is “LOST” as HEAT ENERGY and is not passed on.

PYRAMIDS

PYRAMID OF ENERGY

Recall from an earlier lesson that we can represent ENERGY TRANSFER in an ecosystem with a pyramid of energy, and that only about 10 % of energy is passed from one trophic level to the next.

There are 2 other types of pyramids that are USEFUL GRAPHICAL INDICATORS of ecosystem patterns:

PYRAMID OF BIOMASS

PYRAMID OF NUMBERS

PYRAMID OF BIOMASS

BIOMASS

The mass of an organism WITHOUT water; its dry

weight. Measured in kg.

Water weight varies greatly in living tissue, so it is more

accurate to eliminate it.

A PYRAMID OF BIOMASS is a graphical

representation of the TOTAL BIOMASS of all the

members of each trophic level.

Often similar in shape to a Pyramid of Energy.

PYRAMID OF BIOMASS

PYRAMID OF NUMBERS

A graphical representation of the TOTAL NUMBERS

of all members of each trophic level in a food

chain.

Sometimes, these are shaped liked pyramids, but

there are exceptions!

PYRAMID OF NUMBERS

AN EXCEPTION:

For example, if the following was a rough sketch of our

pyramid of energy, would the pyramid of numbers look

the same?

PYRAMID OF NUMBERS

ANSWER:

No, of course not! There would be more caterpillars

than any other organism, so our “pyramid of

NUMBERS” would look like:

HOMEWORK

Page 39, # 3, 4, 5, 7, 14

Draw 3 pyramids (energy, biomass, and numbers)

for the following food chain:

HAWK (1, 10 J, 5 kg)

WOODPECKER (10, 100 J, 10 kg)

WORM (1000, 1000J, 50 kg)

FIR TREE (1, 10000J, 150 kg)

ROLES IN ECOSYSTEMS

It is time to discuss some of the interrelationships that

take place in ecosystems between species.

Some specific roles organisms can take on include:

KEYSTONE SPECIES

ECOLOGICAL NICHE

INTRASPECIFIC VS. INTERSPECIFIC COMPETITION

EXOTIC SPECIES

KEYSTONE SPECIES

A species that is considered so important to ECOSYSTEM STABILITY, that if that species declined, the ecosystem might collapse.

Why is it called “keystone”?

It is an analogy for a keystone that holds together an archway.

Example:

SEA OTTER is a keystone in the

CALIFORNIA KELP ecosystem

Without otters, kelp does not grow.

SEA OTTER . . .

http://www.youtube.com/watch?v=epUk3T2Kfno

http://www.grinningplanet.com/2004/06-22/keystone-species-article.htm

ECOLOGICAL NICHE

An organism’s NICHE is its “role” that it plays in a

particular ecosystem.

It includes everything an organism does to survive and

reproduce, including:

Feeding relationships

Habitat

Breeding grounds/behaviours

Activity times

Competitive relationships

Organisms tend to have UNIQUE niches, based on

where and how they are best adapted to survive.

ECOLOGICAL NICHE EXAMPLE

Galapagos Island Finches

Found on the Galapagos Islands, 600 miles west of Ecuador in South America

This island is estimated to be 4 million years old, and largely untouched by human impacts for the bulk of its existence.

Charles Darwin studied these finches in 1835 and his studies helped him navigate the theory of EVOLUTION in his book, THE ORIGIN OF SPECIES.

By most accounts, a windstorm blew one finch species to the island.

Left undisturbed for many centuries, and with very little competition and many available niches, this little finch evolved into many SUBSPECIES , all adapted to a DIFFERENT NICHE.

GALAPAGOS ISLAND FINCHES . . .

http://www.youtube.com/watch?v=l25MBq8T77w

SPECIES COMPETITION

Sometimes in nature there is COMPETITION for NICHES when two or more organisms have similar requirements for SPACE, FOOD, and/or WATER.

“Survival of the Fittest” usually prevails

2 MAIN TYPES:

INTRASPECIFIC COMPETITION

Between the SAME SPECIES

EX:

___________________________________________________

INTERSPECIFIC COMPETITION

Between DIFFERENT SPECIES

EX:

____________________________________________________

INTRASPECIFIC COMPETITION

Same species competing

INTERSPECIFIC COMPETITION

Different species competing

penguins versus pelicans

EXOTIC SPECIES

These are NON-NATIVE species that are not natural parts of ecosystems.

Compete INTERSPECIFICALLY with native species in the area.

Examples:

Moose in NL – 4 in 1904

Green Crab in Atlantic Canada

Zebra Mussels (p. 42-44)

http://www.youtube.com/watch?v=4-K1wrn8mDI

Invasive Species in the Great Lakes video

EXOTIC SPECIES – GREEN CRAB

HOMEWORK

Read p. 42-44

P. 44, # 2, 3, 4