Thanks for stopping in to learn about our Macroinvertebrate Survey!
We are JMU students studying environmental science, and as part of our capstone class, we performed a study to analyze the health of Big Run, a stream in Page County, to see how it is affected by agricultural practices.
We are excited to share what we learned about Big Run and the relationship between agriculture on stream health. As you explore the page, feel free to click on the photos, maps and graphics to view a larger version.
First, we’ll give you a little bit of background about the EMJ farm. The farm was previously in pretty bad shape. One conservationist who looked at the area called it a ‘nuclear wasteland.’ As you can see in the first picture below, the herd of 200 cows had over-grazed the area, leaving the soil completely exposed. The cows also had access to the stream, so both sediment and manure were being directly deposited into the water.
In June of 2012, Scott Plein and the White House Farm Foundation purchased the site, and they are in the process of implementing three best management practices (BMPs) to improve the land and the water quality. These practices include planting native trees and grasses along the stream bank to create a riparian buffer to filter water before it enters the stream, using a rotational grazing system for the cows so they don’t overgraze the area, and planting permanent vegetation on the hill to prevent erosion. As you can see in the second photo above, it’s already on its way to recovery.
With these newly implemented conservation practices, we wanted to assess Big Run’s overall stream health over time, taking into account the stressors (manure, sediment, etc.) from the EMJ farm. We expected that the water running through the farm would be of poor quality because of the prior land misuse, but our prediction was that over time, the water quality would improve with the help of the newly implemented BMPs. Our preliminary study was done at a perfect time to use our data as a baseline to show how the stream progresses as the BMPs continue to stabilize the stream bank.
To do this, we did a comparative benthic macroinvertebrate survey of the stream. A benthic macroinvertebrate survey is a way to determine the health of a stream based on the pollution tolerance of the organisms living in the area. Benthic macroinvertebrates are perfect for this type of survey because they don’t move around much, and they have different sensitivities to types of pollution such as sediment, nutrients or warmth.
For our survey, we compared three stream sites, as demonstrated on our map.Comparative Bioassessments of Big Run Maps Our control site is located at the base of Massanutten Mountain. Since the stream flows through the George Washington National Forest, we thought this would be the ideal stream health measurement for comparing our results. Our middle site is right after the stream flows through a subdivision, in order to show a progression as the water flows through the lowlands. Our farm site is located on the EMJ farm, in order to assess the effect of runoff from the area.
The method we chose to conduct our sample is the Virginia Save Our Streams method. This is a very simple, commonly used technique that is easy to replicate for future tests by other groups. Here is an overview of how we did it:
Start by selecting a stream riffle in a shallow, swift moving area, with lots of cobbles. Place a kick seine net downstream of the location and perpendicular to the flow of water. Make sure the weighted end of the net is sunken in the streambed so that organisms do not escape underneath the net. Tilt the net backward slightly, and then use a timing device to sample the area for 20 seconds. Timing the Bioassessment For the first 15 seconds of the sample, scrub and overturn the rocks, disturbing organisms from their habitat site. For the last 5 seconds, kick the rocks and sediment, dislodging burrowing organisms. Then, remove the net from the water, being careful not to lose any organisms, and place the net on a white cloth or tarp on the stream bank. Count the organisms and separate them by species. Then tally the organisms using
The tally sheet provided by VASOS. Repeat this process until 200 organisms have been collected. You may increase the sampling time as necessary, but do not exceed 90 seconds. Once you have tallied all of the organisms, calculate the metric using the sheet provided by VASOS.
For a more detailed description of the process, as well as the data sheets required to perform the survey, click here to download the VASOS guide.
This method uses a multi-metric index from 0 to 12. Any values between 0 and 7 get a rating of ‘unacceptable ecological condition,’ a value of 8 is considered a ‘gray zone,’ and values between 9 and 12 get a rating of ‘acceptable ecological condition.’
After performing the survey and calculating our metric, we got the following results:
- Control Site: 11 – acceptable ecological condition (survey conducted on 10/25/13)
- Middle Site: 11 – acceptable ecological condition (survey conducted on 10/25/13)
- Farm Site: 6 – unacceptable ecological condition (survey conducted on 10/19/13)
We then compared these results to streams in the Shenandoah Valley, and displayed the comparison in a histogram.
In analyzing our results, we concluded that the headwaters of Big Run are of an acceptable ecological condition. However, as Big Run flows through farmland, the water quality degrades. This degradation is likely due to agricultural inputs such as manure and sediment. While the metric we used was not perfect, we believe that this method can be used in the future to continue to track the stream health over time.
How You Can Get Involved:
We also see great potential for future research on this topic. We predict that water quality on the farm site will improve as the BMPs continue to stabilize the bank. However, there needs to be continued biomonitoring of Big Run in order to demonstrate this positive change over time. If anyone is interested in getting involved to continue this testing, please contact Dr. Christine May at email@example.com.
We hope that the data we have collected, in concert with future data, will be a powerful tool for conservation planners to encourage the use of conservation practices on farms. We also see this as an opportunity to demonstrate the timeline of how long it takes for stream health to recover after the environment has been severely degraded. Both of these future uses will provide an important source of public information about the relationship between agriculture and water quality.
If you have any questions or comments about our project, please feel free to fill out a contact form and your inquiry will be directed to us!
Thanks for your interest!