Science of aquatic biomonitoring

Monitoring [or studying]  biological communities such as fish, invertebrates, and algae gives us a picture of the health of an ecosystem.  Different monitoring programs will focus on certain types of biological organisms to study.

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Monitoring biological communities

Biological monitoring complements testing water for chemicals (chemical monitoring) because aquatic life can be affected by:

  • the effects of chemicals interacting with each other
  • contaminant releases are not always detected
  • unknown contaminants
  • introduction of exotic species
  • habitat degradation in the water or surrounding land
  • climate change
  • changes in water levels, flows, and timing (ice formation and spring thaw)

Using organisms to show environmental change

CABIN collects benthic macroinvertebrates at a site location and uses their counts as an indicator of the health of that water body.  Benthic macroinvertebrates are aquatic, bottom-dwelling animals without backbones, that are generally visible to the naked eye. They include worms, crustaceans, molluscs and the larval stages of many insects.

Macroinvertebrate communities have many advantages as biological indicators:

  • They reflect conditions at specific locations and also show cumulative impacts
  • They are sensitive to a variety of disturbances
  • They are present in all fresh water ecosystems
  • They are a key part of aquatic food webs
  • Their assessment methods are well-developed

Reference Sites

Reference sites represent habitats that are closest to “natural” before any human impact. The data from these sites are used to create reference models. CABIN partners use these models to evaluate their test sites in an approach known as the Reference Condition Approach (RCA).

Using the RCA models, CABIN partners match their test sites to groups of reference sites on similar habitats and compare the observed macroinvertebrate communities. The extent of the differences between the test site communities and the reference site communities allows CABIN partners to estimate the severity of the impacts at those locations.

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Crayfish (Decapoda) are omnivores meaning they eat both plants and animals. Photo: Heather McDermott ©Environment Canada 2010

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