Biological Pollutants Flashcards
Why are invasive species important?
Considered to be 2nd greatest threat to global biodiversity after habitat loss
[Earth Summit, Rio Convention 1992]
Where are invasive species the greatest threat to biodiversity?
On islands
Most threatened ecosystem?
Marine
What is the process behind Streelman & Danley’s (2003) speciation & adaptive radiation?
Major habitat diversification -> trophic diversification -> sexual selection
Endemic fish to the three East African lakes?
Cichlid family
Major habitat diversification for Cichlids?
Rock dwelling mbunas, group in sandy environments, pelagic genera
What is the difference between the different Cichlid clades?
Morphology and feeding preferences
Trophic diversification for cichlids?
directional selection on oral jaw
Sexual selection for cichlids?
species-assortative mate choice when colour visible, otherwise largest
Invasive fish species in Lake Victoria?
Nile Perch
When was Nile Perch introduced to Lake Victoria?
1950s
How many cichlid species went extinct as a result of Nile Perch?
200
Why was the Nile Perch introduced to Lake Victoria?
To improve fishery success
What % of biomass in Lake Victoria is the Nile Perch
> 90%
When was the Nile Perch population boom?
1980s
Which bordering country enforces controls on exploitation?
Uganda
When was the rubber boom in the Amazon?
1879 - 1912
Positives of the rubber boom?
Generated wealth, transformed culture and society
Negatives of rubber boom?
Increase in European colonization, damaged indigenous society
Which city did the rubber boom largely increase?
Manaus
What caused the end of the rubber boom?
Import of rubber seeds from Brazil to Royal Botanical Gardens - started industrial rubber industry in Malaya [British Empire]
What determines a species to be invasive rather than non-native? (4)
Establishes/reproduces successfully, spreads efficiently, high likelihood to harm economy/other species/humans
Definition for invasive species?
Alien species which becomes established in an ecosystem, is an agent of change, and threatens native biological diversity
(International Union for Conservation of Nature and Natural Resources (IUCN), 2000)
When was New Zealand pygmyweed introduced in England?
1927
When did New Zealand pygmyweed spread in England?
1956
What is the unique characteristic about New Zealand pygmyweed?
Grows during night, blanketing other vegetation
Why does New Zealand pygmyweed grow during night?
Adapted to hot conditions in New Zealand
How many non-native species have been introduced to the US?
> 50,000
Direct impacts of invasive species? (5)
Disease, predation, hybridization, parasitism, interference competition
Indirect impacts of invasive species (3)
Habitat alteration, economic loss, scramble competition
What do the ecological impacts of non-native species depend on? (3)
The invading species, invasion extent, vulnerability of ecosystem
Which non-native species threatens the survival of Scottish seabirds?
European hedgehog
When was European hedgehog introduced to Outer Hebrides?
1974
Why was European hedgehog introduced to Outer Hebrides?
To increase biodiversity
How are European hedgehogs causing population decline for Scottish seabirds?
Eating their eggs
(The Independent, 2001: London)
What misconception was made about European hedgehogs before their introduction?
They are strict insectivores with no effect on fauna
(The Independent, 2001: London)
Which invasive species is predating on the chicks of seabirds on Gough island?
House mice
When were house mice introduced to Gough island?
19th Century
How were house mice introduced to Gough island?
Sealing ships which moored up
What differentiates house mice on Gough island from regular house mice?
Larger size
Why are house mice bigger on Gough island?
Bigger on islands & at higher latitudes - cold environments [Bergman’s rule]
When was Ruffe introduced into Loch Lomond?
1982
Population (caught on trash screens) change in Ruffe 1982 - 1985?
8% to 76%
Native fish of Loch Lomond?
Powan
Common predators found in Loch Lomond?
Pike and Grey heron
What did the introduction of ruffe cause in terms of predation pressure on adult powan?
Decline
What did introduction of ruffe cause in terms of population pressure on powan eggs?
Increase
Examples of predation as impacts of invasive species? (3)
European hedgehogs, house mice, ruffe
When were rhododendrons introduced to Victorian Ornamental Gardens?
1800s
What are the impacts of rhododendrons? (2)
Produce dense thickets where nothing else can survive
Thick leaf canopy allowing little light through
Which habitats can rhododendrons invade?
Woodlands, heath, grasslands & sand dunes
When was Himalayan balsam introduced to Britain?
1839
When did Himalayan balsam become established?
1855
Impacts of Himalayan balsam? (4)
Grows in dense clumps - preventing light reaching shorter plants
Stops grasses from growing - increases risk of riverbanks washing away
When die in autumn, leave bare patches of soil - more easily washed away by rain
Produces more nectar than native European species - lures pollinating species away
Methods to decrease Himalayan balsam populations?
Cutting, pulling up plants by hand, applying herbicides
Problem with managing Himalayan balsam?
Must not be disturbed whilst fruiting - explosive pods spread seeds
Positive for Himalayan balsam seeds?
Cannot say dormant in soil for long - can be reduced in short period
Examples of competitive impacts of non-native species? (2)
Rhododendrons and Himalayan balsam
How are feral pigs introduced to new habitats?
Escaped or released from domestic life
Impacts of feral pigs? (6)
Uproot plants with leaves or stems
Open tree-fern trunks (Griffin, 1977)
Consumption of fruits of invasive weed, distribute seeds through droppings
Predators of seabirds
Affect agricultural crops - sugar cane
Spread disease
Management of feral pigs?
Hunting with dogs, poisoning
