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Ausable Bayfield Conservation Authority

Benthic invertebrates

For information on Benthic Invertebrates visit the Watershed Report Cards page.


Benthic means occurring at the bed or base of watercourses (e.g., streams, rivers, and other bodies of water such as lakes, oceans and seas).

Benthic Invertebrates

Benthic invertebrates are small aquatic organisms that live in stream sediments and are a good indicator of water quality and stream health. Benthic invertebrate assemblages are reflective of not only water chemistry, but also substrate (i.e., stream bottom) conditions (Lammert and Allan 1999; Richards et al. 1993; de March 1976).

Substrate conditions vary across watersheds and therefore efforts were made to be as consistent as possible when sampling benthic sites. Sampling sites for the watershed report card process were of the highest quality substrate that supports the best possible invertebrate communities.

Benthic invertebrate scores indicate that animals that are tolerant to organic pollution dominated the communities. Common species that were found in the ABCA area include worms, riffle beetles and some insects that are tolerant to nutrient enriched conditions.

Sites in the Middle Ausable and Mud Creek watersheds appeared to be more degraded than most other sites in this area. Benthic invertebrates are small animals, without backbones, that live in stream sediments.

Benthic macroinvertebrates

Benthic macroinvertebrates are commonly used as indicators of aquatic environmental quality. ‘Benthic’ refers to the bottom of lakes and rivers whereas ‘macro’ refers to the subset of larger or visible invertebrates: generally ¼ to ½ mm in length. Invertebrates are animals without backbones such as insects, crustaceans, molluscs, and worms. Benthic region The benthic region is the bottom of a body of water, supporting the benthos.


Benthos is the plant and animal life whose habitat is the bottom of a body of water.