Climate change effects on biological indicators and implications to biomonitoring

Water quality agencies use biomonitoring and biological criteria to assess the status and health of ecosystems as required by the Clean Water Act.  Therefore understanding biological responses to climate change, and interactions between climate change and other stressors, is important to support continued ability to interpret bioassessment results. We selected four regionally distributed state biomonitoring data sets to evaluate existing evidence for biological responses to climate change, focusing on benthic macroinvertebrates.  We found regional differences in observable biological responses, and in the responding trait and taxonomic groups.  Ecological traits of temperature and hydrologic preferences were often important in explaining biological responses, as were traits related to ability to resist or recover from disturbances.  Suggestions are made for how sensitive indicators and trait groups can be integrated into biomonitoring approaches.  Various adaptations of current monitoring approaches are considered that may augment ability to account for climate changes and support the interpretation of biomonitoring results, such as revised reference location criteria and protection; dedicated sampling of regional sentinel sites; and additional ancillary data, including long-term temperature monitoring, and documentation of land use and other habitat characteristics.  Implications for analytical approaches to define and separate climate change effects are also discussed.