Over the past month the students involved in the Bergton Stream Restoration Project have been collecting a large quantity of macroinvertebrate samples. What are macroinvertebrates you ask? These are the organisms that live in the stream that have no vertebrata. More specifically, we are focusing on mayflies, stoneflies, and caddisflies. The presence or absence of these organisms can help determine the health of a body of water. In this image, we see the first step of macroinvertebrate collection. The person collecting searches under rocks, undercut banks, or vegetation, with a net, and then dumps that sample into a bucket to be processed.
For sampling purposes, the stream is divided into three different categories: runs, pools, and riffles. The image here depicts what would be called a riffle, a fast moving area of water that is decreasing in elevation. A pool is a deeper area that has little movement, and a run is a shallower continuation of the stream. We would expect to find an abundance of macroinvertebrates in the riffles due to the higher oxygen levels created by the riffling of the water and the shelter provided by rocks.
After the students empty the contents of their nets into a bucket (as seen above), the contents are then dumped into a white tray where students go through and pick out all of visible organisms with forceps and place them in a vile of ethanol solution. The organisms are then taken back to the lab, sorted by species, and counted to gain an accurate assessment of the stream area in which they were collected. The process of collecting macroinvertebrates can be seen in the following video.
*As a disclaimer, this video contains many crayfish, and crayfish are actually not a part of the study though they are appealing to people.
The two students in this image are conducting water tests to determine the quality of the the water in the stream. These tests measure oxygen, nitrates, phosphates, turbidity, and bacteria. High oxygen content is important for a lot of more fragile organisms such as the brook trout. When nutrient levels are high and the water isn’t clear it is usually due to an eroding bank or lack of riparian vegetation upstream (vegetation on the bank that hinders erosion). This excess sediment is carried down stream and eventually to the Chesapeake Bay. All of the waters here in Virginia end up in the Chesapeake Bay, and thus it is extremely important to take care and keep the water quality high and promote the health of the Bay.
This is an eroded stream bank in a cow pasture in Bergton. This sight is common along streams in cow pastures. As talked about in the previous image, the sediments that were here are now in the water somewhere. This causes problems down stream and ends up causing problems in the Chesapeake Bay. The most powerful thing that we can do for the Bay is change the headwaters. Headwaters are the source of the water, and you can’t change the Bay without changing these waters.
One other aspect of the water that we will be sampling is the fish population. Fish shocking is a common technique for assessing the populations of fish in a stream. A device is used to briefly shock fish which causes them to flash for a moment allowing a netter to quickly snatch the fish. Then, all of the fish collected are counted, processed, and released. These organisms are also crucial to determining the health of the stream.
Here are two fish caught during the fish shocking. One of the fish is the common chub and the other is another species of chub. A sample was taken back to a lab to be later identified, but for the purposes of the day it was known as the “mystery chub”.
The first sampling period of this project has ended for the winter, and now the students will spend time going through the samples that were collected in the field and analyze them for future reference. The data that is collected now will serve the purpose of comparison for when the actual stream restoration has taken place. This will allow us to quantify the changes that have been made to the stream.