On Saturday, July 19th, freshwater ecologist and emeritus professor Dr. Mark Oswood came to share his expertise in the Highland Wonders series. This event aimed to increase our community’s understanding of stream ecology, and how riparian zones and streams interact to support and affect populations of aquatic insects. Connections were made between populations of aquatic insects and what their presence indicates about water quality.
Kick sampling with a D-net provided a wide array of macroinvertebrates to study, including a large stonefly larva. Participants gathered around several tables to work on identifying the aquatic insects using laminated charts and magnifying lenses.
The group gathers to observe the stonefly larva, streamside.
Lee works to identify a macroinvertebrate larva using a laminated chart and magnifying lens.
Holly observes life on a rock pulled from the stream.
Crayfish found in Myers Creek
Thank you, Mark, for your generous contribution of time and energy in preparing for and offering this excellent learning opportunity for our community!
(Above: Mayfly in the family Heptageniidae; note gills on abdomen of larva; also note that this is one of the relatively few mayfly taxa with 2 tails instead of the usual 3 for mayflies)
Large stonefly larva found in Myers Creek
Underside of stonefly
This green pupa is a free-living caddisfly (Trichoptera), which means that it doesn’t make a case unless it is pupating. This is a Trichoptera family that is entirely predatory and eats other insects, and is almost always long and green (in this part of the world). Other Trichoptera (caddisflies) usually use silk to make cases or spin capture nets for filter-feeding.
Another free-living caddisfly (Trichoptera)
Caddisfly (order = Trichoptera), in the family Brachycentridae
Listen to Mark Oswood describe how these macroinvertebrates build such perfect four-sided cases (556 KB)
Mark Oswood lives in the Wenatchee area, retired from the department of Biology and Wildlife and the Institute of Arctic Biology at the University of Alaska Fairbanks, with a research specialty in freshwater ecology. Mark focused mainly on running waters (streams and rivers), with an emphasis on aquatic entomology (the scientific study of insects) and trophic structure of stream ecosystems. He has taught limnology (freshwater science), ecology of streams and rivers, aquatic entomology, as well as introductory biology. Most of his research was on ecology of stream insects, especially biogeography, and decomposition of organic matter. Mark has applied experience studying the effects of heavy metals from mining on streams, and has a side specialty in statistical analysis.
Throughout his career, Mark has taught a wide variety of “introduction to stream ecology” events in classrooms, Elder Hostels, and for government agencies, fly-fishing groups, and conservation organizations. “Seeing the diversity of invertebrates that live in streams can be analogous to a first experience looking at tide pool organisms,” he says. “Plus, aquatic insects are a stream’s way of turning green algae and brown leaves into fish food.”