Poster Details
AN ICONIC MACROINVERTEBRATE IN PERIL: IMPACTS OF INCREASING WATER TEMPERATURES ON PTERONARCYS CALIFORNICA IN SOUTHWESTERN MONTANA
Salmonflies (Pteronarcys californica) are both ecologically and economically important, attracting anglers and providing a significant food pulse for aquatic and terrestrial species. Anecdotal evidence and historical datasets suggest that salmonfly populations may be declining and shifting life history patterns. We measured salmonfly abundance, biomass, and emergence along the Gallatin and Madison Rivers in southwest Montana to determine the status of salmonfly populations and initiate long-term monitoring. Initial findings suggest that in the last fifty years salmonflies are emerging earlier due to reduced snowpack and warmer Spring water temperatures. Larval counts remain consistent in the Upper Madison, but the once robust population has reached critically low to absent levels in the relatively warmer Lower Madison River. In the last twenty years, the Gallatin River population has remained within natural annual variation, but evidence indicates that the population center is moving upstream where water temperatures are cooler. Future laboratory experiments will mechanistically test the influence of water temperature and fine sediment additions on the survival and life history of this iconic species.
Heidi Anderson (Primary Presenter/Author), Montana State University, heidieliseanderson@gmail.com;
Lindsey Albertson ( Co-Presenter/Co-Author), Montana State University, lalbertson@stroudcenter.org;