Why are changes in population numbers of wild animals and plants monitored?
manage species used for food and raw materials
control pest species
monitor polution levels using indicator species
protect and conserve endangered species
What is the maximum sustainable yield (MSY) of a population?
The number of individuals that can be removed from a population without affecting its future productivity
Give an example of a food species that humans manage
Fish - overfishing causes stocks to crash eg cod in Great British waters. Fishing quotas "aim" to manage this situation
Red deer - Adult red deer no longer have predators since wolves were made extinct in the UK. Their population is not naturally held in check and deer are culled to keep them at an optimum level
What are pest species?
Species that are harmful to humans, animals and crops
Give an example of a pest species
Biological methods can also be used to control pests. Give an example of a biological method of controlling a pest
Ladybirds control aphids
What does monitoring the indicator species that are present in an ecosystem give a good indication of?
The "health" of the ecosystem
Give an example of an indicator species
- simple plants which vary in their sensitivity to sulphur dioxide. They indicate the level of atmospheric pollution by this harmful gas
Fresh water invertebrates
- can be used to indicate the level of pollution / oxygen concentration in water.
Mayfly nymph and stonefly nymph - clean water / high oxygen concentration
Rat-tailed maggots and sludgeworms - badly polluted water / low oxygen concentration
Give an example of an endangered species
Why is it important to protect endangered species?
In order to:
maintain genetic diversity
keep a balance and stability in the ecosystem
Higher Biology - Unit Three - Monitoring Populations