Tis the Season for Bug Sampling

As a child growing up in rural central Ohio, parts of my summers were always spent catching crayfish, minnows, and bugs out of local streams. The thrill that came with getting pinched by a monster crayfish when you were not expecting it was comparable to catching my first big fish. Twelve years later and I can still be found catching critters out of a stream, only it is no longer just because of the thrill.

Every spring and summer biologists, environmental scientists, watershed coordinators, and even volunteers take charge on local creeks, streams, and rivers in search for clues to help determine the quality of our water. Typically, these “water guardians” examine three aspects of these water bodies; habitat assessment, water chemistry, and biotic sampling. A habitat assessment is an in depth observation of how natural habitat’s are sustained throughout a set distance of a stream. This takes into account everything thing from riparian (stream banks) vegetation to the amount of substrate sediment present. Water chemistry analysis is also explored in these studies and can give information such as water turbidity, temperature, pH, dissolved oxygen content, and conductivity.

Habitat and water chemical assessments only give information as to if the body of water is capable of sustaining life. Biological (biotic) sampling, also known as benthic macro-invertebrate collecting, is then the defining key in identifying what actually can live in your creek, stream, or river. At FLMR, we train volunteers and even do our own sampling with three pieces of equipment. The first piece is called a Hester Dendy. How does it work? Well, the Hester Dendy is tied off and the heavy portion is submerged in your water body for a 6 week or so period. When collected and examined this then gives a quantitative measure of biota within your stream.

The next piece of equipment for collecting aquatic bugs is a simple dip net. A dip net, much like fishing nets, is used to collect bugs in those hard to reach places. Aquatic insects that are a little more tolerant of colder waters tend to live in overhanging tree roots that have been eroded away by water. These are the perfect areas to use a dip net.

The final, and most important in my book, piece of collecting equipment is known as a kick seine. Kick seines are another quantitative piece of sampling equipment because they allow for sampling of multiple insects at once. Collecting with a kick seine is quite simple but does require at least two people. One person holds the seine so that the water current will run through it and the other person agitates the substrate by continually kicking about 10 to 20 feet in front of the seine. Bugs that are hiding underneath of rocks will be swept into the current and carried to the seine.

Collecting bugs is not just for fun, they can tell us something about our water. These bugs are much like humans in that they can tell you about the environment they live in. For instance, bugs like mayflies, stoneflies, and Dobson flies can only live in very little amounts of polluted water. These organisms will not be found in deep pools in a river, but more so in areas that are highly oxygenated like riffles and runs. Other organisms like leeches, aquatic worms, and snails are very tolerant to pollution. These are the types of organisms that would be found in brackish dirty waters.

So, the next time you play in a stream, take the time to flip over a few rocks and see what kinds of bugs are living there. If not many bugs are there then it may be time to bring in the professionals from FLMR.