An integrative approach to reveal community responses to multiple stressors

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Global decline in biodiversity is estimated to involve a several-fold greater loss of species than before the onset of human pressures, being most pronounced in freshwater ecosystems. Here, ecologists are often surprised by the cumulative impacts of these novel and extreme anthropogenic environmental changes, or "stressors," especially when their combined effect does not equal the sum of their known individual effects. While much research has focused on the properties of the stressors and their interactions to explain such non-additive effects, relative little consideration has been given to how the affected species themselves and their interactions may mediate community responses and ecosystem processes (e.g., primary production). Consequently, there does not exist a well-developed conceptual framework in community ecology upon which empirical investigations can be built to examine the net effects of multiple stressors. Here, I focus on empirically upgrading the often cited Species Co-tolerance Concept (SCC) to advance it as a tool for revealing the nature of community responses to multiple stressors from a mainly freshwater perspective. The primary tenet of the SCC is that the correlation of species tolerances of various stressors determines their combined impact on community-level properties (e.g., species richness, total production); however, it has remained in need of hypothesis-testing and further refinement. Our recent discoveries point to the SCC requiring an improved species-based null model, and also better integration of species interactions and their traits to make it more predictive and mechanistically insightful. Over the next five years, my short term objectives involve determining how integration of these factors into the SCC affect its potential for groundbreaking predictions and understanding of community responses to simultaneous or sequential exposures to stressors. Extensive training of HQP is at the core to the success of my research program. I personally mentor and assist HQP in their design and start of field and lab studies, subsequent quantitative analyses, and communication of their findings. I take a comprehensive approach to training HQP in standard to novel and advanced algal and invertebrate taxonomic techniques, developing skill sets that are increasingly in demand yet short in supply in the environmental sector. I also foster active transfer of skills in my lab to develop mentorship in senior lab members, while also strongly encouraging a highly collaborative and diverse lab environment. I am particularly excited that our findings will lead to textbook-changing advances in community ecology by placing it more in a global change context while also addressing the need for better environmental risk assessment of the cumulative ecological impacts of multiple stressors.