Impact of student-induced disturbance on stream macroinvertebrates differs among habitat types.

Environmental impacts from ecotourism and outdoor recreation activities on terrestrial and aquatic ecosystems are well-reported in the literature, but less is known regarding the impacts of outdoor environmental education activities. Student activity during stream classes may cause substrate disruption and localized impacts on stream macroinvertebrates. We hypothesized that student activity would negatively impact macroinvertebrate community structure in three habitat types (riffle, run, pool) within a site regularly used for stream classes while no impact from student activity would occur in the same three habitat types within an unused site. We addressed the hypothesis by sampling macroinvertebrates monthly for one year in the riffles, runs, and pools at the class site and the unused site within a fourth order stream in central Ohio. The results indicated reduced macroinvertebrate abundance and richness in the riffle at the class site during periods with student activity and no differences between site types during periods without student activity. No impacts of stream classes on macroinvertebrate communities were observed in runs or pools. The results suggest that environmental education organizations should avoid repetitive use of the same site for their stream classes to avoid reductions of macroinvertebrate abundance and taxa richness that can impact the students' educational experience.

Behavioral correction to prevent overhydration and increase survival by larvae of the net-spinning caddisflies in relation to water flow.

We report behavioral regulation of body water content in caddisfly larvae, Hydropsyche morosa and Cheumatopsyche pettiti, by selecting microhabitats with different water flow rates. The purpose of our study was to examine features necessary for survival in the same apparent habitat, because the two species co-exist in riffle areas of freshwater streams. Both species are highly sensitive to water loss as a result of high water loss rates and depend on immersion in fresh water (hypo-osmotic) to maintain water stores. In contrast to C. pettiti, H. morosa is larger, retains water more effectively, and features reduced water loss rates with suppressed activation energies. When H. morosa was confined to areas of low or no water flow, overhydration led to rapid mortality, whereas the same conditions favored water balance maintenance and survival in C. pettiti. In attraction bioassays, H. morosa moved and remained within areas of high water flow and C. pettiti preferred areas with low water flow. Because water flow rates are unlikely to directly impact water gain, the mechanism responsible for increased survival and water balance maintenance is likely related to the impact of water flow on oxygen availability, differences in feeding ecology, or other underlying factors.