ENERGY FLOW IN ECOSYSTEMS

ENERGY FLOW IN ECOSYSTEMS

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.

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

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.

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

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:

C

H

O

+ 6 O

 6 CO

+ 6 H

O + Energy

HOMEWORK



 Page 33

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.

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

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

SEA OTTER . . .

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

GALAPAGOS ISLAND FINCHES . . .

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

INTERSPECIFIC COMPETITION

 Different species competing

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

HOMEWORK

 

 Read p. 42-44  P. 44, # 2, 3, 4