chapter 4: ecology

species

a group of species that can interbreed and produce offspring

population

a group of organisms of the same species, habitat and living area, and time

community

different population groups living and interacting in the same area

habitat

where a species resides in, location of a living organism

ecosystem

a community of organisms and their biotic and abiotic environment

autotroph

organism that produces its own organic compounds from inorganic sources (often referred to as producers)

heterotroph

an organism that consumes organic compounds from other organisms for energy/organic matter (eg. humans, often referred to as consumers)

mixotroph

an organism performing both autotrophic and heterotrophic functions

consumer

heterotroph that eats living organisms via. digestion

detritivore

heterotrophs that consume debris/waste via. internal digestion (e.g. earthworms, woodlice)

saprotroph

heterotrophs that consume dead organic matter via. external digestion (e.g. bacteria and fungi)

mesocosm

enclosed environments with controlled conditions, often used to study sustainability

transect

a sampling method that measures locations along a straight line or to identify where to start quadrat of habitats or elevations

quadrat

sampling method that is used for measuring species in several random squares or circular locations within a specific area

photoautograph

organisms that perform photosynthesis to gain energy

chemoautograph

organisms that obtain energy fro chemical processes (e.g. certin bacteria)

photosynthesis formula

6CO2 + 6H2O \------\> C6H12O6 + 6O2

trophic levels

the position an organism occupies in a feeding sequence

trophic level 1

producers

trophic level 2

primary consumer (herbivores)

trophic level 3

secondary consumer (carnivore, omnivore)

trophic level 4

tertiary consumer (carnivore)

energy transformations

- input: 100% eaten
- stored: 25% tissues
- lost: 25% respiration
- lost: heat 40%
- lost: 10% excretion

different forms of chemical energy

- light energy
- kinetic energy
- electrical energy

biomass

the total mass of organism groups consisting of carbon compounds

exothermic

releasing thermal energy

carbon exchange forms

- atmospheric gases: CO2 and CH4
- oceanic carbonates: bicarbonates dissolved in water and calcium carbonate in corals and shells
- organic materials: carbs, lipids, proteins
- non-living remains: detritus and fossil fuels

carbon compounds

1. CO2 is in the environment
2. CO2 in the environment get removed by plants via photosynthesis
3. animals feed on those plants
4. CO2 gets put in the environment via cell respiration
- CO2 levels in autotrophs are always low via photosynthesis
- the concentration gradient allows for passive diffusion for CO2

compensation point

the net CO2 assimilation is zero (input \= output)

aquatic conversions

1. CO2 in the environment
2. CO2 dissolves in the ocean
3. combines with other compounds to make calcium carbonate (limestone and shells)

formation of calcium carbonate

1. CO2 in the atmosphere dissolves in the ocean and becomes aqueous
2. CO2 combines with H2O to become carbonic acid
3. carbonic acid then turns into bicarbonate and also releases hydrogen ions
4. bicarbonate turns into carbonate, releasing the other hydrogen ion
5. calcium and carbonate form calcium carbonate

methane

1. animal ruminants
2. animal ruminants turn into methanogens
3. methanogens release methane

methanogens

archaean microorganisms that produce methane as a metabolic by-product of anaerobic conditions

anaerobic conditions (conditions without oxygen)

- wetlands (swamps and marshes)
- marine sediments (lake bed mud)
- digestive tract of ruminant animals (cows, sheep, goats)

methanogen examples

- acetic acid releases carbon dioxide and methane
- carbon dioxide and oxygen release methane and water

stages of methane production in a ruminant

1. hydrolysis - polymers to monomers
2. acidogenesis - monomers to alcohols
3. acetogenesis - alcohols to acetate (methane produced as a by-product)
4. methanogenesis - acetate to methane (CO2 released as a by-product

oxidation of atmospheric methane

1. oxygen is added to methane
2. it makes carbon dioxide and water (vapour)
this is why methane is not as prominent as carbon dioxide

fossil fuels

1. plants and animals decompose
2. the bacteria in the soil is fossilized
3. fossils are extracted
4. fossils are burned as fuels

partial decomposition

when organisms don't decompose completely, can occur when waterlogged regions lack oxygenated air spaces in the soil possessing anaerobic conditions
- anaerobic respiration in these regions produces organic acids resulting in acidic conditions
- saprotrophic organisms cannot function effectively in acidic conditions, preventing decomposition

peat

soil that is formed from partial decomposition

coal formation

1. when peat deposits are compressed under sediments, heat and pressure force out impurities and moisture
2. the remaining material has a high carbon concentration and undergoes a chemical transformation to form coal

oil/natural gas formation

1. sediments are deposited on top of the organic matter, creates anoxic conditions which prevents decomposition
2. the organic material becomes heat and hydrocarbons form as a result of the burial and compaction
3. hydrocarbons form oil and gas, which are forced out of the source rock and accumulate porous rocks

combustion

1. fuels are put in cars
2. cars release those fuels when used
3. carbon dioxide goes back into the atmosphere

combustion reaction

combustion reaction occurs when a hydrocarbon is heated with oxygen: hydrocarbon and oxygen react to form carbon dioxide, water, and heat

combustion sources

- fossil fuels: rich in hydrocarbons when compacted underground for millions of years, heat and pressure over time triggers a chemical transformation resulting in the compaction of the organic matter, non-renewable energy
- biomass: living organisms produce hydrocarbons as a part of their biomass, the hydrocarbons are extracted and purified to produce an alternative fuel source, renewable energy

carbon fluxes

an estimated rate of exchange of carbon between various carbon sinks/reservoirs, depends on the conversions involved

gaseous dissolution

the exchange of carbon gases between the ocean and atmosphere

lithification

the compaction of carbon-containing sediments into rocks within the Earth's crust

gigatonnes

1 billion metric tonnes

greenhouse gases

gases that trap heat in the Earth's atmosphere (e.g. carbon dioxide, water vapour, nitrous oxide, methane)

factors that affect greenhouse gas impact

1. ability to absorb long-wave radiation - gases that have a greater capacity to absorb the long wave radiation will have a greater impact
2. concentration in the atmosphere - the greater gas concentration, the bigger the impact, also determined by the rate and persistence of gas within the atmosphere

greenhouse effect

a natural process which allows the earth's atmosphere to act as a greenhouse gas and traps the heat
- incoming radiation from the sun is a shorter wave radiation (UV)
- the earth absorbs the shorter wave radiation and re-emits a longer wavelength (infra-red)
- greenhouse gases absorb and re-radiate the longer wave radiation therefore retaining heat in the atmosphere

deforestation

an anthromorphic activity increasing greenhouse gases - cutting down trees allows all of the CO2 in the autotrophs to exit and stay in the environment

agriculture/increased cattle farming

clearing land for cattle grazing, the cattle produces methane

combustion

fossil fuels are combusted to release energy, CO2 is released as a by-product

greenhouse effect impact

- more frequent weather conditions (eat waves, powerful rainstorms)
- some areas will become more drought affected, more areas prone to extreme rainfall
- changes to circulating ocean currents - can cause longer El Nino (warming) and El Nina (cooling) events

ice cores

ice cores from Vostok station in Antarctica shows evidence of environmental conditions, by analyzing the bubbles trapped in ice, CO2 levels and air temperatures can be deduced