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Macroinvertebrates

Looking at what was in their leaf pack is very interesting to students of all ages...

A caddisfly larvae

Benthic macroinvertebrates -  "water bugs" - play a key role in stream health and as indicators of water quality because they differ in their abilities to tolerate pollution. They live on the bottom (benthos-),  have no backbones (invertebrates), and are large enough to see with the naked eye (macro-).  Some are intolerant of any pollution and some are quite tolerant. They are important links in the food chain, being an intermediate link between higher and lower feeding levels by providing a source of food for fish, birds, amphibians, reptiles and other macroinvertebrates.   

There are many types of macroinvertebrates that live along the stream bottom. Since each type has a different degree of tolerance for pollution, their presence or absence can be an indication of the health of the stream. Usually the pollution is from excess nutrients or sediments that cause low oxygen levels. Generally mayflies, stoneflies and caddisflies have the lowest tolerance to pollution while midges, leeches, worms and blackflies have the highest. In the middle, "somewhat tolerant", range are crustaceans, beetles and craneflies.

Most aquatic insects spend the greater part of their lives as larvae. It is this stage that is most commonly found in the stream bottom. They inhabit all types of stream habitats such as riffles, runs, and pools. To find the most diverse population, riffles are the best place to look, as they are the most oxygen-rich.
 

Collecting Macros

• Using Leaf Packs to collect macros

• Using Kick Nets to collect macros

• Macroinvertebrate Activities
  

Leafing through a Leaf Pack

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For questions about this website please contact Sherry Schaaf, WVC Water Quality Coordinator at sschaaf@esd114.wednet.edu

Middle School students use a kick net to collect macros

Just picking up rocks in the stream, turning them over, and looking will yield macros.  Return the rock to its original position!