干旱区生态环境知识资源中心

Both temporal and spatial trends analysis was conducted to determine if the condition of the benthic community of a residential California stream represented by metrics measuring richness, composition, tolerance/intolerance and trophic composition has changed from 2006 to 2015. A secondary objective was to determine if 10 habitat metrics and total habitat scores measured concurrently with the benthic assessments have also changed temporally or spatially over the same 10 year time period. The 2006 to 2015 time period for this study included both non- severe drought (2006-2008), and severe drought (2013-2015), years. The most significant results from this study were that the conditions of the benthic communities as well as the physical habitat conditions have declined in this water body from 2006 to 2015. Both non-chemical (habitat and water quality parameters) and potential chemical stressors (metals and pyrethroids) were evaluated to determine their possible role in the decline in benthic community conditions. The factors most likely contributing to the decline in benthic communities during the 10 year study period are declining physical habitat conditions measured by declining metrics such as velocity/depth/diversity, channel flow status and riparian areas and possibly low dissolved oxygen concentrations below effects thresholds. Both declining physical habitat and low dissolved oxygen concentrations are likely related to the severe drought conditions reported during 2013-2015.