Underwater Creatures, Cool Measures of Quality

Water in the Elk River will never look the same to me. Under that glassy clear surface are cool critters. Without a backbone, large enough to see with the naked eye, these larval stage insects live in this watery world for weeks, years or for their entire life.

Last month I mucked about in an urban creek taking Streamkeepers training. Amongst the discarded bicycles wedged in river sediment and rusting shovelheads were wriggling, crawling creatures on the rocks, floating in the water and trapped in the river gravels.

We saw ancient species like stoneflies, around since before the dinosaurs. Leaving caddisfly undisturbed on the rocks we witnessed worm like bodies emerge from spectacular stone casings glued together from the labium, a gland in their lower lip. Weightless in water, they drag around their protective homes coming out to perform elaborate dances, wiggling back and forth, then up and down. A huge dragonfly nymph, called ‘scratchers’ by local kids, when placed in a magnified bug box illustrated the inspiration for alien characters in movies with their powerful jaws that shoot out to snatch prey.

After collecting our .5-meter square sample by gently rubbing the rocks to dislodge the critters into our D net, we took our buckets up to the bank to sort and count the diversity. In record time, under three minutes, a mayfly nymph crawled out of the water, split open its exoskeleton and squeezed out of its shell. Pumping up lacey wings, it rested looking like giant sails over its back. Investigating closer with a magnifying glass, the head was all eyes but no mouthparts. Alive for only a day or two, they only have one focus – locate a mate, lay eggs, and die. No time for frivolity like eating!

Wading for two days in an urban stream learning about techniques to protect and look after our watershed, I developed a new appreciation for fishers. Walking in waders across slippery rocks is tricky business. Standing around in cold water in the rain is not for sissies either. Clearly there is great skill and talent required to match man-made flies with the hatch coming off the stream. Master fly fishers require excellent entomology skills to identify the hatch and then match it to the appropriate fly in a tackle box. This probably explains why local fishing Masters like John Poirier catch fish after only a few casts.

In the Elk River the three bell-weather benthic or bottom dwelling invertebrates are plentiful. As indicators of water quality, the presence of the key three EPT or Ephemeroptera/ mayflies, Plecoptera/stoneflies and Trichoptera/ caddisflies – tell us something about the health of our river. All are sensitive to water degradation by pollution and thrive in a cold-water fishery containing high levels of dissolved oxygen. Celebrate their abundance in our river – a great sign!

Looking for these animals is fun and easy to do with all ages. What you need is a white bucket, kitchen sieve or net, rubber gloves and a safe place to wade into a river or stream. Facing upstream put your net on the bottom and pick up rocks. Look first for delicate caddisfly casings. Don’t disturb them! Rub the smooth areas on several rocks and the current will wash the creatures into your net. Dump the contents into your bucket and take it up to the shore. Using plastic spoons sort them into white ice cube trays sorting creatures that are similar and different. Look at them with magnifying glasses from the dollar store.

Investigate the head looking at the eyes and antennae. Where are the gills for breathing - under the leg joints, on the abdomen or paddle like appendages from the tail? Look at the legs and feet – how many hooks help anchor it to rock? Is the body flat or rounded? How many tails does it have and are they oar-shaped, feathery or long and straight?

Photo by Sanne van der Ros