What is a Macroinvertebrate?

Macroinvertebrates serve as bioindicators in freshwater ecosystems. The majority of stream macroinvertebrates are benthic, meaning they inhabit surfaces like the channel bottom, bedrock, cobble, sediments, or stable structures such as fallen trees and submerged vegetation. Their residence along the channel bottom, visibility to the naked eye, and the absence of a backbone are distinguishing factors that qualify them as macroinvertebrates. Macroinvertebrates inhabit nearly every freshwater ecosystem worldwide, even in seemingly harsh conditions.




Why are they important?

Macroinvertebrates form the foundation of the aquatic food chain, providing essential sustenance for a range of animals, including amphibians, birds, reptiles, and fish. In freshwater ecosystems, macroinvertebrates contribute to nutrient cycling by breaking down organic matter, including living and decaying plant material. As they feed on this organic material, they release nutrients back into the water, contributing to the cycling of elements like carbon, nitrogen, and phosphorus. This process is a fundamental part of healthy aquatic systems.


Quantifying overall aquatic ecosystem health can be a challenge, given the multifaceted nature of factors influencing it. Certain macroinvertebrates have high sensitivity to variations in water quality. Due to this sensitivity, some macroinvertebrate species are regarded as excellent bioindicators - meaning that their well-being closely reflects ecological conditions!


Determining whether an ecosystem is healthy or assessing the impact of human actions on it requires effective measurement tools.

Scientists have developed indexes of biological integrity tailored for watershed assessments. These indexes provide a quantitative score for the overall health of a watershed, based on its macroinvertebrate community. 

For watershed assessments, macroinvertebrate sampling serves as a crucial tool, offering insights into the ecological conditions and overall well-being of the watershed ecosystem.


Hauer, F. R., & Resh, V. H. (2007). Macroinvertebrates. Methods in Stream Ecology, 435–454.

 Luell, S., Vaisvil, A., Admin, & Blogger, G. (2020, April 21). The importance of macroinvertebrates in freshwater streams. Fish Habitat Section of the American Fisheries Society.

Michaluk, S. (2022, October 21). macroinvertebrate. Encyclopedia Britannica.