Field, Forest, & Stream: Stream Ecology - Eva Varga

With our STEM Club, we recently undertook a three part ecology study I call, Field, Forest, & Stream.  We met at a local preserve with a fabulous outdoor classroom space and spent the day inundating ourselves in outdoor science. Today, I share with you the activities we enjoyed as a part of our stream ecology lesson. 

Stream Ecology

Streams and their surrounding riparian areas provide essential habitat for a variety of fish and wildlife species. To maintain a healthy population of fish and wildlife, a habitat must provide food, water, cover from predators, breeding, nesting, and rearing areas, and protection from heat and cold.

Healthy riparian areas provide most or all of these elements for fish and wildlife species. “Riparian” means riverbank, and “riparian area” refers to the border of moist soils next to a body of water, and the plants that grown there. A small stream with steep banks could have a riparian area that is only a couple of feet wide, but a large lake in a broad valley could have one several hundred feet wide.

Stream Survey / Habitat Assessment

Many factors go into making up a riparian area that is healthy and meets the needs of a variety of species. The data we gathered as a part of our habitat assessment evaluates many of the key indicators of the condition of these important areas. Typically, an authentic riparian area habitat assessment evaluates eleven different parameters, we focused on just a few to simply gain field study experience.

Bottom Substrate

Substrate is the material that makes up the bottom of the stream. It can be a good indicator of land use activities and gradient upstream. It determines what types of macro invertebrates can live there and the suitability of the site for fish and spawning. A diversity of types and sizes of materials is considered to be better habitat than just fine materials such as silt and sand. The bottom substrate affects the characteristics of flow, the quality of the water, and the suitability of habitat for instream life.

Channel Shape

Channel shape can be an indicator of other forces at work in the steam and of conditions at other times of the year. Is the shape a natural product of stream forces, influenced by the actions of humans, or a combination of both?

Velocity of Current

Fast-flowing water is generally more turbulent than slow-moving water.  Turbulence is one factor that influences concentrations of dissolved oxygen.  Both fast and turbulent flow require different living strategies for organisms found in these reaches. To calculate the current velocity, we measured a 50ft distance along the shore. We then used a stopwatch to calculate the time it took an orange to float this distance. V=50ft/x sec.

Interested in undertaking this study yourself? Field, Forest, & Stream is part of the Life Logic: Ecology Explorations unit that I have developed for middle school students. What better way to learn about ecology than to get out there, collect data, and experience the physical factors that influence the animal and plant communities first hand.