envr 1000 - unit 2, structure & function of ecosystems, pt 1

Starfish example purpose

Demonstrates importance of control groups in experiments

Scenario one setup

Coastline contaminated with toxin affecting small organisms

Toxin effect

Barnacles and mussels affected, starfish unaffected

Experimental action

Starfish removed from a specific cove

Missing control group

No untouched comparison site

Observed outcome

Other species die off

Incorrect conclusion

Species decline attributed to absence of starfish

True cause

Toxin caused die-off, not starfish removal

Scenario one error

Confusing correlation with causation

Scenario two setup

Coastline contaminated with toxin affecting small organisms

Experimental group

Starfish removed from one cove

Control group

Second cove left untouched

Observed result

Both coves experience species die-off

Interpretation

Same outcome regardless of starfish presence

Correct conclusion

Starfish absence did not cause species decline

Hypothesis outcome

Hypothesis not supported

Control group importance

Reveals unseen external factors

Causal interaction definition

Relationship where one cause contributes to an effect

Cause and effect

Direct influence between variables

Multiple causes

Natural phenomena often have many contributing factors

Scientific challenge

Narrowing down possible causes

Example causal question

Starfish populations and ecosystem health

Medical example

Drug use and change in pain

Variable control

Helps isolate true causal relationships

Lake Washington case study

Ecological imbalance caused by nutrient pollution

Effluent input

Sewage increased phosphorus levels

Scientific finding

High phosphorus linked to cyanobacterial growth

Cyanobacteria impact

Formation of dense surface scum

Bacterial response

Increased decomposition of cyanobacteria

Oxygen depletion

Dissolved oxygen levels dropped

Biological consequence

Fish and invertebrates died from low oxygen

Management action

Effluent diverted beginning in 1963

Sewage elimination

All sewage stopped by 1968

Recovery outcome

Water quality improved and cleared

Long-term result

No cyanobacteria overgrowth since

Ecology definition

Study of interactions among organisms and their environment

Biotic components

Living parts of ecosystems

Abiotic components

Non-living environmental factors

Scientific links

Ecology connected to geology, chemistry, and physics

Levels of organization

Pyramid of ecological complexity

Population definition

Same species in same place at same time

Community definition

Multiple interacting populations

Ecosystem definition

Community plus physical environment

Landscape definition

Multiple interacting ecosystems in a region

Landscape ecology

Study of ecosystem connections

Biosphere definition

All regions of Earth that support life

Earth spheres

Atmosphere, lithosphere, hydrosphere

Matter definition

Anything with mass that occupies space

Matter examples

Atoms, compounds, ions

Energy definition

Ability to do work

Energy effects

Changes position, composition, or temperature

Potential energy

Stored energy

Kinetic energy

Energy of motion

Thermodynamics study

Energy and its transformations

Energy flow

Conversion between potential and kinetic energy

Bow and arrow example

Potential energy converted to kinetic energy

Energy transformation definition

Change from one energy form to another

Bungee jumper example

Gravitational potential converted to kinetic energy

Chemical bond energy

Potential energy stored in molecular bonds

High-energy molecules

Sugars contain high bond energy

Low-energy products

Water and carbon dioxide

Energy release

Potential converted to kinetic energy

Carbon dioxide stability

Strong double bonds cause persistence

Music box example

Demonstrates multiple energy transformations

Key turning

Kinetic to elastic potential energy

Spring release

Elastic potential to kinetic energy

Sound production

Kinetic energy converted to sound

First law of thermodynamics

Energy cannot be created or destroyed

Energy conservation

Total energy remains constant

Energy conversion

Energy changes form

Photosynthesis definition

Plants convert light energy into chemical energy

Cellular respiration

the metabolic process in which cells break down glucose and other organic molecules in the presence of oxygen to produce adenosine triphosphate (ATP), the primary energy currency of the cell

Biological work

Energy used for growth and maintenance

Second law of thermodynamics

Usable energy decreases over time

Heat definition

Disorganized and less usable energy

Energy loss

Some energy always converted to heat

Entropy definition

Measure of disorder

Entropy trend

Entropy increases over time

Efficiency limit

No process is 100 percent efficient

Earth systems definition

Interacting components influencing each other

Cycle definition

Movement of matter through systems

Hydrologic cycle example

Water moving through Earth systems

Systems approach

Considers interconnections among issues

Environmental perspective

Not human-centered

Trade-offs

Solving one issue may affect others

Open system definition

Exchanges energy and matter

Lake example

Receives water and loses water

Energy inputs

Solar radiation and geothermal heat

Closed system definition

Exchanges energy but not matter

Matter cycling

Matter remains within system

Scientific models

Closed systems easier to study

Natural reality

All environmental systems are open

Causal interaction in systems

Mutual influence among components

Linked processes

Process one affects process two and vice versa

System change

Feedback can shift entire system

Feedback loop definition

Output feeds back as input

Negative feedback

Stabilizes a system

Negative loop effect

Opposing forces balance change

Positive feedback

Amplifies change

Positive loop effect

Drives system toward extremes