IB Biology, C3, human impact on ecosystems

Define endemic species and give an example

A species only found in limited, restricted, definesd areas / habitats and having no trace of them in other parts fo the world (meerkats to Madagascar p)

Define alien species

A species outside of its natural range and dispersal potential, spread intentionally or not by human activity

Name 3 done by invasive species

Predation, habitat destruction, competition

Outline the Caine toad

- They we're originally introduced to Australia to eat sugar cane destroying bugs

- They are highly poisonous

- They we're ineffective

- They harm natural / native species

- They breed quickly

How was the Caine toad combatted?

- killing with carbon monoxide after capture

- train gun predators to avoid them

How does plastic harm wildlife?

- clogging environments

- damaging habitats

- animals eat plastics

- tangling in waste

- toxic chemicals from plastic are poisonous

Give an example of effected animals by plastics

- the Laysan Albatross has a high proportion of number of birds dying due to plastic in intestinal tracts

Name 5 ways to reduce plastic waste

- avoid single use plastics

- recycle

- use second hand materials

- practice local shopping

- purchase non-packaged items

What do pesticides in food chains cause?

Bio accumulation

Define bio accumulation

Build up of toxins in the food chain

Give an example of bio accumulation

Minamota mercury poisoning

Outline the process of bio accumulation

- pollution / toxins by humans are absorbed by plants

- primary consumers eat plants taking in small toxin concentrations

- toxins can't be excreted so remain in animal tissue and are passed through trophic levels

- concentration of toxins is greatest at the top of the food chain

Define biomagnification

When the concentration of a toxin is highest at the top of a food chain

Give an example of an introduced pollutant

DDT (pesticide)

Outline DDT

- effective in killing malaria carrying mosquitoes (1950s)

- "silent spring" by Carson illustrated how DDT poisoned the whole food chain (1960s)

- banned for agriculture in the US due to side affects in humans and killing other species (1962)

What is the impact of environmental disturbance on biodiversity?

Decrease biodiversity:

- decreased population size

- decreased habitat number

- higher competition between species

Increase biodiversity (temporary):

- heavy rains in desert systems

How do alien species impact an endemic species in ecosystems?

- decreased population of prey

- decreased population of endemic species

- decreased biodiversity

- increased population of alien species

- disturbed balance between prey and predator