Families Learn about the Relationship Between
Benthic Invertebrates and River Ecology
with Hilltown Families & Biocitizen
Halloween’s upon us and the leaves are almost down—and for river lovers that means it’s time to do Rapid Biotic Assessments (RBA), which involves capturing and cataloging the bugs—benthic invertebrates —that live on the riverbed. Certain bugs like stonefly-nymphs need lots of oxygen to survive, and when you find a bunch of them, it’s a sign that the river water is fresh and clean and that aquatic habitat is unimpaired. Given that in the last two years we’ve endured the yin and yang of weather extremes—hurricane last year, drought this year—we’ve been especially concerned that our river bugs are reeling from the stress.
A few days ago, on a lucky afternoon when the clouds parted and the sun warmed our shoulders, Hilltown Families conducted its yearly RBA in West Chesterfield. We forged into the bracing current of the East Branch of the Westfield River and at 3 sites where the water churned white we reached down into the numbing cold and scrubbed bugs off rocks and the riverbed; dislodged, they floated into our EPA approved net. On shore, we emptied the nets into basins and “oohed” and “ahhed” at the first signs of buggy abundance. I could see after our 1st sampling that the river was healthy; the drought had not decimated the bugs.
It’s always hard to imagine that these bugs have inhabited our local streams and rivers for plus or minus 20,000 years (when the glaciers that polished the tops of Mts Holyoke and Tom were melting). It’s hard to imagine because, strangely, we are not taught to think about time—we remember dates, for sure, like July 4, 1776; but even that date seems remote, as if it was ancient history. History itself begins about 5,000 years ago, with the cuneiform records kept by original inhabitants of what is now Iraq; and what seems so long ago in human terms, is really not so long ago in benthic invertebrate terms. Every time I see a sprightly stonefly-nymph rushing hither thither through the leaves and pebbles in the collection basin, I am filled with a reverence and respect, and yes awe. We have been here for less than 400 years and, compared with these tough and resilient natives, are just newcomers. They know what they are doing, and they do it with such grace and determination—weathering 20 millenia of floods and droughts, no prob!
Now that we’ve conducted 3 annual RBAs just downstream of the Route 143 bridge in West Chesterfield, MA, we are beginning to see fluctuating patterns in population size. This year we found lots of case-building caddis-fly nymphs, and less stoneflies. We surmised that the rather extreme difference in population sizes is evidence that the caddis-fly, with their hermit-crab-like body-casing, was better adapted to the summer’s drought conditions than the stoneflies, whose body-tissues are less-protected and more exposed. The water was quite warm, too, because of the drought, and warm water is considered “thermal pollution” because it contains less oxygen than cold water, and because native fish such as brook trout begin to die when the temperature gets above 70 degrees; it was way above that during the drought. Our guess—and we do freely guess because we are not experts; we are amateurs in the best sense of the word—is that the caddisfly-nymphs were better able to migrate to and stay in cold, highly-oxygenated habitat than the rest of the river bugs. We’ve never seen so many!
Our most impressive catch was a pair of giant stoneflies; and giant is the correct adjective because they dwarf all other river bugs, in the way an elephant dwarfs a horse. We made a promise to learn more about the stoneflies’ life-cycle, and part of that education will involve us notifying each other when we see the stonefly hatch next spring. Trout fishermen are keenly aware of the hatches, so seeing them out on the rivers will tell us the hatch is happening. This is what an adult winged stonefly look like; I bet you’ve seen them! What is so amazing is that not only do they live two separate lives in two separate elements, but also that they are the prime food of the trout, and if there’s lots of them, there will be lots of trout, and if there are lots of trout, they will attract lots of fish-eating birds and mammals; and it just so happens that this year bald eagles and otters inhabited the East Branch! Without lots of benthic invertebrates, these beautiful “higher order” beings would never have showed up.
Biocitizen will conduct a few more RBAs in the Northampton area next week or two, and you are welcome to join us. Next year, we are rolling out a much more ambitious RBA program, in the hopes of getting more citizen scientists, and plain old nature lovers, to adopt their local stream or river. The more we know about these river bugs, the more we will know about the health—and beauty and unique character—of our Nonotuck and Hilltowns’ biomes. And the more we know those things, the more we will know about ourselves—for where you are, is who you are.
ABOUT THE AUTHOR
Kurt Heidinger, Ph.D. is the Executive Director of Biocitizen, non-profit school of field environmental philosophy, based in the Western MA Hilltown of Westhampton, MA where he lives with his family. Biocitizen gives participants an opportunity to “think outside” and cultivate a joyous and empowering biocultural awareness of where we live and who we are. Check out Kurt’s monthly column, The Ripple, here on Hilltown Families on the 4th Monday of every month to hear his stories about rivers in our region. Make the world of rivers bigger than the world of pavement inside of you!
[Photo credit: (ccl) Evan Leeson]