Human Impact on Biodiversity Flashcards
All 8 cards in this deck
What is biodiversity?
The variety of different species (and genetic variation) in an ecosystem or on Earth.
Why does high biodiversity make an ecosystem more stable?
Species depend on each other for food, shelter and maintaining the environment, so loss of one species has less effect when many alternatives exist.
Give two ways fish farming reduces biodiversity in surrounding waters.
Waste food and faeces cause eutrophication, and parasites/diseases (e.g. sea lice) spread to wild fish.
Name two controls used in fish farming to limit its impact on wild species.
Keeping fish in mesh cages/nets to exclude predators and stop escapes, and treating fish with pesticides or antibiotics to control parasites and disease.
What is a non-indigenous (invasive) species?
A species introduced to an area where it does not naturally occur, either deliberately or accidentally.
Name three ways a non-indigenous species can reduce the biodiversity of an ecosystem.
Out-competing native species for resources, preying on native species, and bringing new diseases/parasites that natives have no resistance to.
What are the steps of eutrophication?
e.g. fertiliser washed from a field into a river
- Fertiliser run-off adds nitrates to the water.
- Algae grow rapidly (algal bloom) and block sunlight, so plants below die.
- Decomposing microorganisms respire and use up the oxygen, so fish and other aquatic animals die.
True or false? In eutrophication, the algae themselves use up all the oxygen that kills the fish.
False. Oxygen is mainly used up by the microorganisms (decomposers) respiring as they decompose the dead plants and algae.