Conservation Corner Small bugs paint us "The Big Picture"

The Nottawasaga Valley Conservation Authority (NVCA) conducts stream monitoring to answer the questions:

Which streams are healthy? Which streams are unhealthy?

How does water quality and habitat in the streams change over time?

Which human activities contribute to poor health of streams?

Do conservation projects result in stream improvements?

Biomonitoring studies involve sampling the communities of living organisms in order to determine ecosystem condition. Then the sample is evaluated; since some species are pollution tolerant and others are highly sensitive, the percent of each in the sample indicates the health of the stream.

In other words, we use plants and animals to tell us whether the environment is clean or polluted. The organisms used are called

biological indicators; the proverbial canary in the coalmine is a classic example. Fish, algae, insects, trees, lichens, and bird eggs have all been used as biological indicators for various forms of pollutants or changing climate conditions.

No single species is a complete indicator, but rather the composition and population of the community of organisms paints a good picture.

Biomonitoring is often cheaper and more descriptive than chemical, l a b o r a t o r y b a s e d monitoring. Since water in streams is always moving, water chemistry can fluctuate widely due to rain, chemical spills, season, and even light levels. However, organisms that live in the stream are constantly exposed and are useful to give current conditions and provide a record of past problems.

For example, infrequent chemical sampling may miss a toxic spill, but the biological community may still be depressed after water chemistry returns to normal. Biomonitoring is often used as a primary assessment tool, with more in-depth chemical testing is done when a problem is found.

A primary indicator used by the NVCA to test the health of our streams is benthic invertebrates, also known as bugs or bottom dwellers, (i.e. mayfly nymphs, clams and crayfish). Aquatic bugs make good indicators because they are:

abundant (they are everywhere in every type of stream)

sedentary (unlike fish who can swim away from pollutants)

easy and inexpensive to collect and identify

responsive to water quality and sediment conditions

not used as an economic or recreational resource (like fish)

In healthy streams we find species such as stoneflies and mayflies, which require cold, clean well oxygenated water to survive. In degraded or polluted watercourses we see different types of worms and fly larvae, which are more tolerant of cloudy, dirty waters.

The NVCA uses its bug data along with its less frequently collected water chemistry and fish community data to assess water quality and habitat conditions in rivers, lakes and wetlands.

This assessment helps the NVCA and its partners focus our protection, restoration and enhancement efforts for maximum benefits.

Biomonitoring is an effective tool that can be used economically, with very few resources. Next time you see a bug in the water, make sure you stop to listen to its story because it tells of the health of our streams.

"Conservation Corner" is a monthly column that looks at the theory, practices, technology and benefits of land & water stewardship.

The NVCA is your public agency dedicated to the preservation of a healthy environment. As your partner, the NVCA provides the expertise to help protect our water, our land and our future.our website at www.nvca.on.ca.