Macroinvertebrate Communities and Habitat Characteristics in the Northern and Southern Colorado Plateau Networks, Pilot Protocol Implementation

Brasher, Anne; Albano, Christine; Close, Rebecca; Cannon, Quinn; Miller, Matthew

This report describes a pilot implementation study of aquatic macroinvertebrates that was conducted at nine sites in eight streams in seven national parks across the Colorado Plateau. Aquatic macroinvertebrates have been identified by the National Park Service Inventory and Monitoring (I&M) program as a vital sign that can indicate the status of aquatic ecosystems in national parks of the Colorado Plateau. Monitoring macroinvertebrate assemblages can complement physical and chemical water-quality assessment methods, and provide a more complete evaluation of watershed condition. Because macroinvertebrates integrate, temporally and spatially, the effects of land and water use in a watershed, they are excellent indicators of both long-term changes and short-term events. Monitoring physical habitat in conjunction with macroinvertebrates provides an important link between macroinvertebrate community composition and anthropogenic activities that can affect watershed quality.A pilot implementation study was conducted at nine sites in eight streams in seven national parks across the Colorado Plateau. Streams for this pilot study were selected to represent a range of habitat characteristics(stream types) and maximize variance across sites. Two types of macroinvertebrate samples were collected in each reach: one from a measured (quantitative) area within a targeted habitat (riffles), and the other a qualitative sample collected from multiple habitat types. Quantitative samples provide estimates of species densities and allow statistical comparisons among sites and over time, while qualitative samples provide a representative species list and information on biodiversity at a site. Physical habitat characteristics, including water depth, velocity, substrate size, and riparian canopy closure, were measured at three spatial scales: reach, transect, and points along each transect. Physical habitat characteristics were also measured at each quantitative macroinvertebrate sample location.Overall, we collected 241 different taxa in 23 orders and 74 families. Considerable differences were observed in macroinvertebrate community structure among sites. The association between variation in macroinvertebrate community structure and habitat characteristics among the eight streams was examined using the multivariate statistical technique of non-metric multidimensional scaling (NMDS). Sampling sites ranged from small, shallow, intermittent streams to a deeper, wider stream with fastflowing water. Percent canopy closure, an indication of shading, also varied widely among streams from sites with little canopy closure to sites almost completely shaded. Most of the sites were dominated by extremely small substrate (sand). Statistical analyses indicated that variables driven by stream size and discharge were largely responsible for controlling the community composition of macroinvertebrates at the sampling sites. The ability to detect differences in macroinvertebrate fauna among streams suggests that this monitoring protocol will also be able to detect differences (changes) in macroinvertebrate communities over time—especially changes associated with alterations to habitat characteristics.

Macroinvertebrate Communities and Habitat Characteristics in the Northern and Southern Colorado Plateau Networks, Pilot Protocol Implementation

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