Aquatic invertebrate monitoring at Homestead National Monument of America: 2005-2007 trend report

Bowles, D

To address concerns about water quality in Cub Creek, Homestead National Monument of America (HOME), Nebraska, the National Park Service (NPS) began monitoring the aquatic invertebrates of Cub Creek within HOME in 1989, although a concerted monitoring effort did not began until 1996. This report summarizes aquatic invertebrate monitoring data collected from 2005-2007 and further evaluates the data with respect to trend since monitoring began in 1989. Invertebrates were collected using Hester-Dendy multiplate samplers placed at two sampling sites on Cub Creek. Additionally, hourly readings of water quality (temperature, dissolved oxygen, specific conductance, pH, turbidity) were recorded at least 24 hours prior to sampling at both the upstream and downstream monitoring sites using data loggers. Water quality measurements were generally consistent and typical for streams of this size in the region although there was modest variation among years. Summary data for invertebrate community metrics from 2005-2007, including genus richness, Ephemeroptera, Plecoptera, Trichoptera (EPT) richness, Shannon Index, Shannon Evenness Index, and Hilsenhoff Biotic Index (HBI) generally did not exceed control chart limits based on historical data collected from 1996-2004. Cub Creek is a prairie stream ecosystem and the extant condition of its invertebrate community may not be too far from an undisturbed condition. The results of invertebrate monitoring clearly show that stream integrity has not diminished beyond that when monitoring first began in 1989, although annual data exhibited substantial variation. Given the known anthropogenic disturbances in Cub Creek upstream of the park it is likely that the aquatic invertebrate communities in Cub Creek within HOME are mildly impaired, however. There are few available options to park management for mitigating this situation, largely because the impacts to water quality originate upstream of the park boundaries. However, maintaining in-stream habitat and riparian zone integrity will aid in maintaining the integrity of Cub Creek in the park. Aquatic invertebrate monitoring in Cub Creek provides a sound tool to recognize both deterioration and chronic decline of water quality, and it will be useful to ensure water quality in the stream does not degrade further.

Aquatic invertebrate monitoring at Homestead National Monument of America: 2005-2007 trend report

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