What's a Healthy Stream?
Beep, Beep, Beep. Four biologists wielding dip nets and wearing funny looking backpacks stare intently into the waters of a small creek. Suddenly, silver flashes as small fishes are drawn toward the scientists by high voltage electricity. Four nets dart into the water in unison and come back to the surface with several species of fishes flipping inside. Great! The equipment is working and fish community sampling has started. It’s a typical scene from a day’s work with the Resource Assessment and Monitoring Program (RAM) field team.
The RAM Program
The goal of the RAM Program is to assess and monitor long-term trends in the health of Missouri’s warm-water streams. There are five factors that affect stream health, and each of these must be balanced for a stream to be healthy:
- Water quality,
- Stream flow,
- Physical habitat (channel shape, rock/soil makeup and vegetation in and around a stream),
- Stream system connectivity (how the watershed interacts with the surface and groundwater), and
- Biotic interactions (the way different species interact).
The RAM Program samples water quality and habitat and compares the information to healthy sites to determine benchmarks for restoration efforts. However, the program’s focus is on the living organisms in streams because their well-being is the ultimate goal of our stream conservation efforts. If we see improvement in animal and plant life, then we know our efforts are effective.
Fish and macroinvertebrates (animals that do not have a backbone, but are large enough to be seen with the naked eye, including worms, mollusks, crayfishes, mites and many kinds of insects) are affected differently by water quality and poor habitat, so it is important to sample a variety of organisms. Traumatic events such as toxic waste or sewage spills, or rain runoff contaminated with herbicides or pesticides, usually kill most fish and macroinvertebrates in an area. Long-term water flow changes and major habitat loss can also destroy these populations.
In a minor, or temporary disturbance, such as low-level chemical pollution, excessive sedimentation or nutrients, or increased flooding, fishes can swim away from the area and return when conditions improve. However, most macroinvertebrates cannot get away. When a community of macroinvertebrates is wiped out, recolonization may not occur until much later.
Healthy aquatic communities have an appropriate balance of species that use stream habitat efficiently. In these communities, there is a wide variety of species, and each tends to have specialized feeding, spawning, shelter