Last week I accompanied Dr David Pierce’s Physical Geology class to a portion of the Chagrin River near the intersection of Booth and Sperry Roads.
The class was on a three-day mission to survey the chemical and biological components of the water. The results of their tests will be sent to the Ohio Department of Natural Resources, the Ohio EPA, and Lake County Soil and Water.
Throughout, I was impressed by how seriously the students addressed their tasks. Groups of 3 or 4 ran chemical analyses of the water. If a group found an unusual reading for an element, the group retested with another sample. If the reading verified the first reading, the students checked with other groups to see if they’d found a similar irregularity.
When the chemical analysis was complete, each group waded into the Chagrin and shoved a flat 3’ x 3’ net under the surface rocks of the river.
They carefully scraped the sand and grit from the bottom of the rocks into their nets and carried the nets and residue to shore.
The students measured and made a geological survey of the types and amounts of different size rocks and sand in the area from which they’d taken samples
Each group carefully picked through the sand and grit to retrieve the tiny wrigglies squirming around and placed them in a flat pan of river water. Then they sorted the creatures by species into an ice cube tray where the specimens were tallied.
Top row, from left to right: Dobsonfly larvae, aquatic worm, cranefly larvae, caddisfly larvae water penny, crayfish
Bottom row, from left to right: Dobsonfly larvae, mayfly nymph, stonefly nymph, young catfish, last square undetermined
Dr Pierce entered the count in a table where the critters’ totals were weighted by x1, x2, or x3, x3 being the factor assigned to organisms associated with clean water.
Both the chemical and biological testings yielded the same result: The section of the Chagrin River they’d tested was in A-Number-One health.
Though not included in the weighted tally, the presence of the two crayfish in the tray (captured by grabbing rather than netting) is especially heartening.
They’ve been scarce for the last several years from disturbances caused by the upstream construction of roads and homes. The crayfish and other macroinvertebrates’ habitat was further degraded a few years ago when a downstream individual drove a bulldozer into the river to remove rocks and gravel.
According to Dr Pierce, crayfish are sensitive to sediment pollution, the inflow of which buries hiding spots and habitat for crayfish. Crayfish gills become clogged. Reproduction suffers. Fewer hunting/hiding spots are available in which to hide from Great Blue Herons and raccoons. In addition, the eggs and larvae of other aquatic macroinvertebrates suffocate and die off, limiting the food supply for the crayfish.
The presence of the crayfish is an indicator that the sediment pollution is slowly coming under control. However, Dr Pierce has repeatedly been denied all access to document any recovery at the site of the bulldozer violation.
The outing confirmed a long-held suspicion of mine that geologists get more than their fair share of fun.
I want a piece of that!
So I’m taking Dr Pierce’s Physical Geology class next quarter.