Wildlife - Indicator Species

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Indicator Species Part 1

  • Can be used to indicate how healthy an environment is.
  • A species whose presence, absence or abundance reflects a specific environmental condition, habitat, or community.
  • Indicator species may:
    • Provide information on the overall health of an ecosystem.
    • Reflect a particular environment condition, such as pollution.
    • Be indicative of a particular habitat type.
  • Why do we use indicator species?
    • Can provide an early warning of environmental change.
    • They can be used to assess the health of an environment or ecosystem – they are often termed ‘bioindicators’.
    • Can be a useful management tool.
  • How might indicator species show changes in the environment.
    • Increase or decrease in abundance.
    • Presence or absence
    • Changes in behaviour
    • Change in physiology or chemically.
      • Could be a slight change in their colouration or the presence of sores.
      • Could take samples from animals that have shown a physiological change.
    • Indicator species may be used passively
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Indicator Species Part 2

  • Considerations
    • Care must be taken when using indicator species as there are some potential pitfalls.
      • Might not be enough to assess the overall area.
      • Need to be sure any correlation shown is real or is a coincidence.
      • Must be liked to the environmental condition and must be studied in a scientifically sound manner to justify its use.
  • May be difficult or time consuming to survey.
  • May be hard work to identify a suitable indicator species.
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Air Pollution

  • Lichens
    • Farmed from a symbiotic relationship between a fungus and an algae
    • They often grow on exposed rocks and trees, and need to be efficient at absorbing water
    • Air pollutants dissolved in rainwater, especially sulphur dioxide, can damage lichens and prevent their growth
    • Different lichens show different levels of tolerance to pollution
      • Shrubby and bushy lichens are usually the most sensitive to pollution and are often absent from polluted areas
      • Crusty lichens are usually more tolerant of pollution and can grow in more polluted areas
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Water Pollution Part 1

  • Many aquatic animals cannot survive in polluted water, so their presence or absence can indicate the level of pollution in water body.
  • Types of water pollution can include:
    • Nitrates (e.g., from fertilisers)
    • Acid rain
    • Heavy metals
    • Pesticides
    • Oil
    • Other chemicals
  • Source of water pollution
    • Urban streets
    • Rural homes
    • Suburban development
    • Cropland
    • Animal feedlot
    • Factories
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Water Pollution Part 2

  • Invertebrates
    • Different invertebrate species can tolerate different levels of water pollution.
    • The composition of species within a study area can indicate the level of water pollution.
    • Mayfly and stonefly larvae prefer clean water.
    • Freshwater shrimp can tolerate low levels of pollution.
    • The water louse can tolerate high levels of pollution.
    • Species such as the rat-tailed maggot and sludge worm can tolerate very high levels of pollution.
    • Mussels are suspension feeders and accumulate heavy metals and toxins in their tissues.
    • Mussels are often used as an indicator species for monitoring the health of coastal environments.
  • Algae
    • Run off from agricultural farms = eutrophication in rivers and lakes
    • The composition and total amount of algae species can indicate the amount of organic pollution.
    • Algae blocks out sunlight so plants cannot survive underneath it.
    • Takes up oxygen from the water.
    • More fish will start dying as oxygen is taken from the water.
  • Amphibians
    • Susceptible to changes in water quality given that they breathe through their skin.
    • Chemicals can cause physical abnormalities and malformations.
    • Amphibians live in water and on land, therefore they are particularly useful for assessing the overall health of an area.
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Climate Change

  • Montane species
    • Live in the mountains and can be good indicators of climate change.
    • Have a specific habitat.
    • American Pika
      • Lives in a very specific habitat.
      • Very low reproductive rate
      • Shows very limited dispersal ability.
      • Extremely sensitive to warm temperatures.
      • As temperatures rise the American Pika is forced to seek higher elevations to seek a higher and cooler and moister habitat
      • However, this species already occupies high elevations.
      • Climate change may already be factor in the extinction of local pika populations.
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Other Examples

  • Top predators – food chains
    • If the predators are decreasing it could be because the prey may be decreasing which would lead to you looking at their food source.
    • Predators are more easily spotted.
  • Plants – soil conditions
    • Most like neutral or alkaline pH
  • Bioaccumulation/biomagnification of toxins
    • DDT – pesticide, insects take in small amount of the pesticide which kills them, this accumulates inside their predators, now banned.
    • African Land Snails have been banned from America due to their destructiveness.
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