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ecology (Limiting factors in population growth (Oxygen (in water)…
ecology
Limiting factors in population growth
Food and Water
Oxygen (in water)
Pollutants like sewage can lower oxygen levels
Toxic waste
Overcrowding
Unhygienic conditions, spread of disease and stress
Predators
Disease
Climate
Drought, floods and storms
Lack of shelter
pyramids
pyramid of biomass
Measures biomass instead of numbers
Biomass = the weight of living material
At each trophic level shows the mass of
the living things (g/m2)
pyramid of energy
Show the amount of energy that is transferred from one trophic level to the next (kJ/m2 )
pyramid of numbers
How many living things are involved in each trophic level
Do not take into account size
EG. An oak tree and grass are each considered as 1 organism
competition and predation
competition
competition between different species
animals that compete with humans are called pests
weeds compete with crops and farmers
Greenfly & whitefly do damage to our crops
cockroaches and rats compete for food
competition between the same species
human: wars
predation
humans as predators
Commercial fishing
Many fish species are overfished
what makes a good predator?
work together to catch prey
migrate to an area with more prey
Predating prey that is young, old or sick
Ability to switch to another prey species
hunt in a pack
prey
Some animals taste horrible! Or can sting
Warning colors
Staying in large groups
Camouflage
Swim, run or fly faster than the predator
biotic and a-biotic
what is biotic
biotic are factors caused by
other living organisms
present in the community
-Predation
animal that feeds by hunting and killing its prey
-Competition
Between individuals of the same species → for example, Nesting sites
Between animals and plants of different species → for example, food
-Disease
Microbes can cause disease
-Grazers
Animals that eat plants. AKA. Herbivores. AKA. Primary consumers.
-Decomposers
Microbes that release enzymes to break down dead and decaying material
Mainly bacteria & Fungi
Very important in the cycling of nutrients
Found in soil, rivers lakes and oceans
-Effect of humans
Industry
Farming
Forestry
Transport
Housing
what is a-biotic
a-biotic are factors caused by non-living things
Estimating population size (Animals)
Animal move, or come out only at night – We have to capture them
Mark, release and recapture method
Collect a sample of animals (M)
Mark the captured animals (small paint dot)
Release the marked animals
Give them a day or two to mix back into the population
Collect a second sample (S)
Count the amount of marked animals in the sample (R)
1 more item...
Estimating population size (Plants)
You do not count all individuals
You take a sample
Use a quadrat – count number of
plants present inside this
Multiply this number by the total amount of quadrats that fit into the habitat you are investigating