| Knowledge of the winter ecology of rivers is deficient for aquatic ecosystems globally and disturbance by ice is often not considered in natural disturbance regimes of rivers. I investigated how disturbance by river-ice affects organic-matter dynamics and feeding ecology of aquatic insects in Big Creek, a 6th - order tributary of the Middle Fork Salmon River in central Idaho, USA. Also, I used opportunistic sampling to investigate how elk (Cervus elaphus) carcasses from gray wolf (Canis lupus) kills, which often occur in rivers or on ice during winter, may serve as resource subsidies to river organisms. I compared samples of biofilm, transported organic matter, and gut-contents of aquatic insects before and after ice break-up events. In addition, I compared dissolved nutrients, biofilm, and diet analyses (gut-contents and stable isotopes) of aquatic insects collected from an elk carcass to samples collected at similar sites without a carcass. Scour associated with 2 ice break-up events reduced the quantity of biofilm by 39% but increased the quality by 41%. Several aquatic insect taxa consumed greater proportions of diatom frustules following ice break-up, although some taxa consistently consumed large proportions of high-quality food resources. Diet analyses indicated that aquatic insects collected from an elk carcass consumed biofilm rather than directly consuming carcass material. This study indicates ice regimes in rivers affect organic-matter dynamics and feeding ecology of aquatic insects. Additionally, this study provides insight to a unique subsidy to river ecosystems and indicates a potential pathway in which predation by wolves may be altering river processes. More research on the winter ecology of aquatic ecosystems is needed to predict potential effects of climate change. |