Development of Functional Trait Measures for Assessing Stream Ecosystem State

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My long term objectives develop and apply novel environmental assessment approaches to establish mechanistic explanations of environmental impacts on rivers. Next, my program will examine functional changes to river ecosystems that occur as a result of shifts in ecological trait composition. Current taxonomically-based methods for diagnosing the cause of degraded river ecosystem conditions are problematic as they are poorly linked to functional measures. In contrast, ecological traits-based information has the potential to provide mechanistic linkages of biotic responses to specific environmental disturbances (e.g., sedimentation, nutrient enrichment). Traits-based approaches have the potential to produce consistent metrics for application across broad spatial scales and associate cause and effect when multiple environmental stressors have cumulative consequences on biological communities.******The proposal uses traits-based bioassessment approaches to create the building blocks for developing knowledge of the interactive effects that exposure to excess nutrients and sediments have on benthic traits-based assemblages in rivers. Specific research objectives are to: (1) use mesocosm experiments to establish the interactive effects of environmentally realistic nutrient-sediment exposures to identify their single and combined effects on the occurrence of benthic community traits, and (2) evaluate the combined effects of nutrients and excess sediments across landscape gradients affected by disturbances that modify riverine nutrient-sediment regimes. This research program will: (1) establish the effects of nutrient enrichment and sedimentation on riverine insects by assessing additive, multiplicative and comparative effects model frameworks; (2) examine the role nutrients may have in masking the sediment effects through manipulative experiments; and (3) test predictions from these experiments along nutrient-sediment stressor gradients affected by intense agriculture and permafrost degradation. Assessment of predictions across distinct watershed disturbances (and different ecozones) will test the general applicability of the method. Key predictions are: (1) river insects will respond to non-lethal stress through decreased body size; (2) negative sediment effects will be moderated by mild nutrient enrichment; and (3) sedimentation will worsen the negative effects of excessive nutrient enrichment. This work will help move regulatory, water quality regimes from simplistic, single stressor effects models to more realistic evaluations of cumulative ecological effects from multiple stressor exposure. HQP engagement includes 2 PhD, 4 MSc, and 5 undergraduate students who will receive extensive training in the communication, leadership and technical skills required for successful careers in the academic, government and private sectors.********