Lessons learned from stream critter science
Recently, Deer Meadow Primary, Central Elementary and Greencastle Middle School had the opportunity to assess the health of local streams. Deer Meadow and Central had the stream brought to the classroom via plastic boxes to assess the stream under consideration while Greencastle Middle School was able to actually access Big Walnut Creek to record measurements and follow-up with a health determination back in the classroom.
Students were assessing the benthic macro invertebrates, words when broken down mean bottom dwelling, large enough to see visually critters without spines or backbones. Stream critters like insects, arthropods, and fish live in a stream year around and depending on the type and species have varying degrees of tolerance to pollution.
Typically, a greater number of species (high level of diversity) indicates positive stream health whereas even a large number of a single species would be indicative of poor stream health. A biological assessment is typically more meaningful than a chemical test since the critters living in the stream year around would be impacted by a short term, singular pollution event. A chemical assessment would most likely miss a short term, singular pollution event since one would not likely be on location during the pollution event.
Furthermore, steam critters have been categorized into four different groups ranging from very intolerant of pollution to very tolerant of pollution. The presence of stream critters like mayfly, stonefly, caddis fly, and dobson fly larva are indicative of a-healthy stream. Right handed snails are indicative of a healthy stream.
A watershed is a land area that shares a common drainage point. Therefore smaller watersheds collectively make up larger watersheds. Everyone has a watershed address that can be likened somewhat to an internet address. For example at the Putnam County Fairgrounds, the watershed address is Big Walnut Creek, Eel River, West Fork White River, Wabash River, Ohio River, Mississippi River, Gulf of Mexico.
Given the knowledge about stream critters, these youth set out to answer the question of whether or not local streams are healthy.
Since annually planted cropland of mostly corn and soybean totals 13 million acres and occupies more than half of Indiana's 23 million acres, agriculture often has a finger pointed at its industry for being detrimental to water quality. Farmers live where they practice agriculture, so it would seem unlikely that they individually would want to be polluters and the chemicals they use do have considerable costs to their operation, making it unlikely that individual farmers would want to use chemicals in excess.
As students went about biological stream assessment activities, they were learning beneficial applications of accounting, identification, and classification. The middle school students also applied math and science knowledge like geometric principles, physical properties like water/air temperatures and chemical testing of dissolved oxygen, nitrate and phosphorus levels. Using all of these data collected in the assessment phase, students concluded the process by utilizing scientific decision making skills.
Both Deer Creek near South Putnam schools and Big Walnut Creek near the Putnam County Fairgrounds exhibited indicators of great stream health and healthy watersheds upstream. Numerous critter species that are intolerant of pollution were found at both locations. Applying the students' conclusion to the specific watersheds, it would appear that agriculture as the primary land use of the land area (watershed) upstream from the two locations is not having a negative impact on either stream.
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