These guidelines were developed to assist citizen scientists in monitoring aquatic habitat following road removal. Roads can have major impacts on water quality and habitat value due to landslides and general erosion of the road bed over time. For fish, increased fine sediment in streams has been linked to decreased fry emergence, decreased juvenile densities, loss of winter carrying capacity, and increased predation. Road removal has been shown to reduce erosion and sedimentation but its impact on aquatic systems has not been well studied. Over time, data collected by citizen scientists can be used to gain a better understanding of the effects of road removal on stream health, including potential benefits to fish habitat.
Water Temperature
In general, aquatic species cannot tolerate wide temperature fluctuations in their habitat. Trout and salmon, for example, require cold water and can be adversely affected when water temperatures increase due to loss of vegetative cover. Fortunately for citizen scientists, temperature measurements can be made with a normal thermometer. Many road segments you may wish to monitor will intersect stream grade channels. Stream grade channels (SGCs) are live water crossings (where water is actively flowing across a road) that have been restored as closely as possible to natural conditions by returning the stream to its original grade and restoring the side slopes as nearly as possible to original contours. Monitoring these channels can be accomplished with many methods, but temperature readings are by far the simplest. Measurements should be made at the top and bottom of the SGC and recorded on the data sheet.
Sedimentation
Erosion of unpaved roads often sends fine sediment into a stream, where it can reduce fish populations. One simple way to measure sediment levels is with a “pebble count.” It can tell us about the relative “texture” of a stream and provide insight into changes in sediment load carried by the stream. Pebble counts can indicate if sedimentation is occurring, or conversely, if the streambed is returning to a more natural state, as we might expect after road removal.
The first step in conducting a pebble count is to identify three channel cross sections, near the top, middle, and bottom of the SGC, running roughly perpendicular to the stream bank. The selected cross sections should be relatively permanent to allow follow up measurements. Pounding rebar into the sides of the SGC serves this purpose, and also allows a measuring tape to be tied in a straight line across the channel.
Once the cross sections are determined, a monitor then makes his or her way across the channel at that line, beginning at bank full height and measuring the size of particles encountered at regular intervals across the stream channel to the opposite bank. Depending on the size of the SGC you are working in, you can make more or less picks per cross section, but a good number for a relatively small channel is 50. Larger streams may require 100 picks. You can also adjust the interval at which you pick, as long as it remains regular as you cross the channel. Many people simply use the width or length of their thumb, hand, foot, or some other readily available tool.
When making a pick, the monitor should look away from the streambed so as to randomize the sample. After a rock or other substrate has been touched, it becomes a pick, and is then measured along its intermediate axis (in other words, not on its longest or shortest side. This pick should be recorded by a second monitor who is observing from the stream bank. Alternately, the particles touched can be brought back to the stream bank for measurement (unless, of course, they are too small or too large to be readily carried – these particles should be measured in the stream). Particle sizes fall within different ranges, each describing a basic type of sediment, from very fine silt to boulders. Be careful when sampling in a stream or river; rocks can be slippery and currents can be flowing more swiftly than you might expect.
Macroinvertebrate Sampling
Macroinvertebrates are animals without backbones, such as insects, worms, and mollusks, which live at the bottom of streams and are visible to the naked eye. Sampling invertebrates tends to serve as a good indicator of stream health and water quality, since there is such a great variety in undisturbed streams. If only a few types of invertebrates are found in the stream you sample, or if they are species that adapt well to streams that are unnaturally warm, cloudy, unstable, or de-oxygenated, then you can assume there is a problem.
In general, for road removal, sampling for macroinvertebrates is another way of determining if streams provide good habitat for fish and other, larger animals that can be more difficult to sample. These small animals are just as sensitive to changes in their environment as trout or salmon, even though we tend to be more interested in fish. It is easier and less intrusive to the environment to sample macroinvertebrates, and can also show a more direct correlation to watershed health than fish sampling might, since anadromous fish can be affected by a variety of factors, including ocean conditions and fishing pressures. Macroinvertebrates spend their entire lives in the streams in your watershed and are primarily impacted by activities within that watershed.
Macroinvertebrate sampling is usually done with a tool known as a Surber sampler, a large net attached to a folding brass frame that catches invertebrates as they are washed downstream. These samplers can be a little pricey, but are well worth the investment if you are planning on measuring macroinvertebrates. You should collect three replicates, putting down the Surber sampler three times for each replicate (you’ll put the sampler down for a total of nine times. You should sample in riffles (fast, turbulent water moving over gravel or cobble substrate) within the main flow and near the middle of the stream, from 4 to 16 inches deep. (Note: This type of sampling is usually done in a fairly large stream, but can be adjusted to accommodate smaller streams with the help of an ecologist.)
The best substrate to sample is one that has 2 to 4 inch rocks with smaller pebbles underneath. Avoid substrates with rocks larger than 12 inches in diameter. Look for an area with the best canopy cover and riparian vegetation that you can find. Ideally, the riffle you sample should be large enough to accommodate all nine placements of the Surber sampler (the three placements of the sampler for a given replicate should be close together, but the different replicates should be at least 6 feet apart). If no single riffle is large enough, sample from adjacent riffles with similar depth, flow and substrate type. If your sampling site seems less than ideal, make a note of it on your data sheet.
Begin sampling downstream and move upstream, avoiding disturbance of terrestrial vegetation overhead or upstream of your sampling site to avoid getting terrestrial insects in the sample. Place the Surber sampler on the selected spot with the net’s opening facing upstream and the collection cup stretched out behind. The current should move directly into the net. Lift larger rocks resting beneath or within the frame and, holding them in the water in front of the net, brush off any crawling or loosely attached organisms so that they drift into the net. After “cleaning” the rocks, place them in a dishpan. Once these rocks have been removed, the frame of the sampler should be squarely on the stream bottom. Note the water depth in inches. Once larger rocks have been removed, disturb the substrate vigorously with a weeding fork for 60 seconds, to a depth of about four inches. Organisms and detritus should wash into the net. This constitutes one “dig” of one replicate. Now, lift the sampler out of the water, keeping the open end pointing upstream. Tilt it up out of the water to help wash organisms into the collection cup. Without emptying the cup, repeat the sampling procedure twice more at nearby spots. These three “digs,” combined in the collection cup, constitute one replicate.
You must then collect the macroinvertebrates that you have sampled and put them into labeled sample jars. This involves rinsing and sieving the samples several times. Also have one or more team members look over the rocks removed from the stream bed with a hand lens, and put any other organisms into the sample jar. Make sure everything is labeled accurately and have the samples analyzed for species diversity. Data sheets for this and other road removal monitoring will be available soon on our website at www.wildlandscpr.org.
— Katherine Court is an Environmental Studies graduate student who is developing a citizen science road removal monitoring program on the Clearwater National Forest.