Environmental Drivers of Macroinvertebrate Stability and Persistence within the Interior Columbia River Basin, USA

Lotic macroinvertebrates inhabit temporally variable environments; however, studies of assemblage dynamics disproportionately focus on short-time scales. Understanding temporal dynamics of macroinvertebrate assemblages is critical to status and trend monitoring, which assumes the long-term stability and persistence of reference assemblages and our ability to discriminate anthropogenic from natural temporal variability. The National Aquatic Monitoring Center is collaborating with the US Forest Service’s PACFISH/INFISH Biological Opinion Effectiveness Monitoring Program (PIBO) to quantify factors influencing macroinvertebrate inter-annual variability. Specifically, we quantified 8 years of macroinvertebrate inter-annual variability for 19 reference and 29 managed sites within the Interior Columbia Basin, USA and related assemblage dynamics to environmental variability and watershed attributes. Macroinvertebrate stability and persistence were relatively high for reference sites; time lag regression slope coefficients did not significantly differ from zero. Furthermore, O/E scores were relatively consistent through time (CV = 15%). In contrast, macroinvertebrate stability and persistence decreased as O/E scores deviated from one (43 and 46%, respectively). The reduced stability and persistence of potentially impaired sites was most strongly related to inter-annual water temperature fluctuations and reach slope. Despite inter-annual changes in environmental variables, macroinvertebrate stability, persistence, and biological condition were relatively stable for reference sites, while impaired sites were less resistant to environmental fluctuations.

Society for Freshwater Science 2010 Presentation

Collaborators

  • Utah State University
  • U.S. Forest Service
  • U.S. Bureau of Land Management

Graph of percent increase of MSE versus temperature, O/E, elevation, LWD, precipitation, stream density erosiveness percent igneous watershed area, CAO, Grazing, percent metamorphic, fire, average d50, site type, percent sedimentary, number of frost days and bank stability average d16
Relative importance of biophysical predictors in explaining variation in average macroinvertebrate stability among 48 sites and 311 individual samples collected throughout the interior Columbia River Basin.

Three line graphs of BC Dissimilarity (P/A) on a range of 0.38 to 0.45 versus elevation ranging from 1000 to 2000, BC Dissimilarity (P/A) on a range of 0.38 to 0.46 versus average temperature on range of 10 to 18, and BC Dissimilarity (P/A) on a range of 0.42 to 0.48 versus average O/E on a range of 0.2 to 1.2 with 0.2 to 0.7 highlighted in red.
Average macroinvertebrate stability as a function of O/E scores, water temperature and road density. Relationships are depicted as partial dependency plots from random forest modeling.