Mayflies, Stoneflies, and Caddisflies

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Written by SOLVE Jesuit Volunteer Corps Northwest Member Nicole Poletto

Clackamas High School @ Rock Creek on 11.13.12

Clackamas High School was geared up in rain boots and ready to assess the water quality of Rock Creek.  But wait, we only need a D-net, a bucket, turkey baster, and an ice-cube tray?  What kind of assessment is this?  We must be catching macroinvertebrates!

Patrick and Daniel from Clackamas County Water Environmental Services taught us how to use macroinvertebrates for water quality testing purposes.  For example, mayflies are generally pollution tolerant while stoneflies are very sensitive to pollution and will only be found in healthier aquatic environments.  Depending on what we catch, we can tell how healthy the stream is!

Brave souls hopped in the gushing and seemingly freezing Rock Creek to find some aquatic friends.  After 3 kicks of the net, we were ready to identify our macros! The goal of the day was to find a type of mayfly, stonefly, and caddisfly.  The students scoured over their identification books and were able to not only to reach their goal, but also found scuds and aquatic worms!

The students thought that the mayflies and stoneflies were the hardest to tell apart.  One way to tell the difference is to look at the way that they are swimming.  Stoneflies usually wiggle sideways like a shark swimming and mayflies wiggle up and down like a whale when they swim.  (Caddisflies resemble caterpillars!)

From top to bottom: caddisfly, stonefly, and mayfly.                         Photo: KY State Natural Preserves Commission Flickr

Our findings from the survey: Rock Creek is a relatively healthy urban stream.  We found two types of stoneflies which are very sensitive to pollution.  It seems like all of our hard work is paying off!  Great enthusiasm Clackamas!

One thought on “Mayflies, Stoneflies, and Caddisflies

  1. Good job this is a great article. I agree with what you have said, but I would ask you to consider this: Mayfly (Ephemeroptera) taxa richness. The diversity of mayflies declines in response to most types of human influence. Many mayflies graze on algae and are particularly sensitive to chemical pollution (e.g., from mine tailings) that interferes with their food source. Mayflies may disappear when heavy metal concentrations are high while caddisflies and stoneflies are unaffected. In nutrient-poor streams, livestock feces and fertilizers from agriculture can increase the numbers and types of mayflies present. If many different taxa of mayflies are found while the variety of stoneflies and caddisflies is low, enrichment may be the cause.

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