Project Fish Bugs Strikes Again
April 18th, 2013
The temperature of Wilson Creek’s rushing waters topped out at 52F degrees at 9AM this somewhat cloudy and breezy day. Rock Bottom Cabins was today’s venue, where we have hosted other Fish Bugs programs over the last two years. Rosemary Young’s advanced biology class students (Grayson County High School) were the chosen ones, all 17 of them.
Aaron Floyd (program director) and I arrived at 8 to set up our work station, and just before the big yellow bus arrived, he caught a brown trout for dissection purposes.
While that enterprise was underway, I noted a lone Louisiana waterthrush grazing on the moss covered rocks across the creek, one hop at a time, feasting on the very macro-invertebrates we were there to investigate. Eventually another showed up, and for the rest of the day, these two waterthrushes chased each other through the rhododendron thickets singing their male territorial songs above the constant chorus of the stream’s drumming bass notes. We pointed out the association of these birds within the ecological balance of their habitat, and the importance of the food chain.
We provided wading boots and seine nets for collecting live macro-invertebrates for our on-site
investigation. Once the net was properly positioned in the ripples, we counted out 40 seconds of collecting, with two net handlers and at least one substrate disturber upstream, turning over and rubbing the rocks. We then brought the nets to the field tables containing ice cube trays, and the sorting began.
It is commonly understood that some critters are good indicators of the health of the stream. A preponderance of snails or mosquito larvae is not necessarily a good sign. This day’s harvest was abundant with May and stone flies…good indicators. And we had plenty to count.
Among the special bugs discovered today were two net-winged midges and an armored mayfly larva. The mayflies had the numbers, well over 100, with stoneflies coming in second. We also counted many common fly larvae such as crane and black flies. In our first sampling, taken in rapid riffle waters, we found but one caddisfly, most of which species are known for their ability to construct protective coverings from local materials. Depending on what’s at hand, some make their cases with small pebbles or sand, some with leaves and sticks. Free-living caddisflies also exist without cases. When Aaron dissected the trout’s stomach, it revealed an exclusive diet of pebble-encased caddisflies, so our second sampling was moved upstream and in somewhat calmer waters near where he caught the trout, and of course, we collected quite a few of the encased caddis.
Other finds included crayfish, a minnow, one snail, one salamander, a water-strider, a couple of dragonfly larva and a hatching mayfly.
It is not our point to describe these animals to the species level, but even managing to categorize to family gives us enough of a challenge at times. We utilize field microscopes to gain that obvious advantage and bring the discovery process closer to the moment.
After the morning‘s schedule of data gathering and assimilation, we regrouped after lunch to document through illustration some of our finds. Every student was given the opportunity to pick a subject and instructed to take their time with pad and pencil. Again, it is BRDC’s strong advocacy to include this documentation component within the field experience, thus expanding the connection potential of a day in the outdoors.
Ms. Young’s class provided us with a great group of kids, and we thank them all. Fish Bugs is funded entirely by the Harris and Frances Block Foundation, without whom, we would not be able to offer this fun, learning by doing, experience.