Impacts of Humans on Ecosystems

Question 1

What is an alien species?

Answer 1

is one which arrives in a non-native habit, usually as the intentional or accidental result of human activity

Question 2

What happens to alien species?

Answer 2

1. die - not able to adapt to environment bc niche is too different
2. become invasive = ecological + economical damage

Question 3

What are some examples of alien species?

Answer 3

1. Zebra mussels (from Russia) accidentally released by ballast water from ships. Now dominate water ways & blocks drains + releases toxins harmful to some species
2. Japanese knotweed is nutritious plant but as been classified as invasive as causes damage to other species (imported)
3. cane toads - introduced to control agricultural crop pests. reproduces heavily & its toxic skin is a threat to other animals & predaotrs

Question 4

What is the competitive exclusion principle?

Answer 4

2 species cannot occupy the same niche in a community, as there will be competition for the same resources

when 1 species has even the slightest advantage over another then the 1 with the advantage will dominate

Question 5

What are some examples of advantages for the competitive exclusion principle?

Answer 5

high reproductive rate

larger size / more aggressive

faster / more efficient forager

ABSENCE OF PREDATOR (often relates to invasive species)

Question 6

What is an example of the competitive exclusion principle in regards to invasive species?

Answer 6

harlequin ladybird - introduced by UK as biological control agent to manage pops. of aphids & other agricultural pests

fundamental niche:

1. broad diet
2. live in broad range of habitats

strong competitor:

1. large size
2. high reproductive rate

consequence:
native ladybird species are being outcompeted & endangered

Question 7

What is biological control of invasive species?

Answer 7

the use / introduction of 1 organism to control another invasive species

Question 8

What is an example of a biological control of invasive species?

Answer 8

rabbit haemmorrhagic disease virus (RHDV) i traduced in Australia to control rabbits

Question 9

What is biomagnification?

Answer 9

a process in which chemical substances become more concentrated at each trophic level

Question 10

What is bioaccumulation?

Answer 10

as each individual consumes contaminated food or filters contaminated water, it is building up chemical substances within one trophic level

Question 11

What is DDT?

Answer 11

dichlorodiphenyltrichloroethane

a synthetic pesticide sprayed on crops & can be used against malaria mosquitoes

now used for disease-control programmes

Question 12

What are the pros of DDT?

Answer 12

affordable & efficient at killing mosquitoes

malaria decreased

alternative strategies not as successful

health costs of trading malaria reduced

Question 13

What are the cons of DDT?

Answer 13

exposure = serious health effects (reduce fertility, genital birth defects, cancer, damage to developing brains)

persists in environment for long periods *15 years or more)

Question 14

What is a microplastic?

Answer 14

plastic debris < 1mm

accounts for ~65% of all ocean debris

Question 15

What is a macroplastic?

Answer 15

large visible plastic debris >1mm

Question 16

What are the consequences of plastic debris in oceans?

Answer 16

suffocation

blockage of digestive track

biomagnification

poisons - some plastics contain toxic chemicals