1. How Will Climate Change Affect Trophic Processes and Productivity in Freshwater-Riparian Ecosystems? Mark S. Wipfli USGS Cooperative Fish and Wildlife Research Unit School of Fisheries and Ocean Sciences & Dept of Biology and Wildlife Institute of Arctic Biology University of Alaska Fairbanks

2. I. Aquatic Food Webs II. Climate Change Effects on Food Webs Freshwater habitat loss from drying Water temperature increases Terrestrial vegetation cover changes Nutrient loading – from land and sea Today’s talk

3. FISH BIRDS nutrients algae and aquatic plants herbivorous invertebrates carnivorous invertebrates Aquatic food web (streams, wetlands)

4. Baxter et al. 2005 Aquatic food web & riparian linkages

5. Terrestrial prey ingestion by fishes Cutthroat trout May JuneJuly AugSeptOct 0.0 1.0 0.2 0.4 0.6 0.8 Proportion of terrestrial prey ingested Juvenile coho salmon Dolly Varden char Wipfli 1997

6. Climate Change Effects Freshwater habitat loss from drying Water temperature increases Terrestrial vegetation cover changes Nutrient loading – from land and the sea

7. Climate Change Effects Freshwater habitat loss from drying Riordan et al. 2006 ↑ drying = ↓ aq habitat, ↓ aq productionResult:

8. Climate Change Effects Water temperature increases Shrinking water body size, warmer soil and air temps, and longer growing seasons will all likely lead to higher water temperatures ↑ temps = ↑ aq production (to a point), ∆ community composition Result:

9. Climate Change Effects on Vegetation Expansion of shrubs (alder, willow, dwarf birch) and spruce along aquatic habitats. Sturm et al. 2001 Kugururok R Climate Change Effects Terrestrial vegetation cover changes (valley bottom)

10. USDA Coop Ext Invertebrates on riparian plants 0 0.5 1 1.5 2 2.5 3 Alder Spruce Hemlock Salmonberry Stink currant Blueberry Invertebrate mass (mg) / leaf mass (g) Allen et al. 2003 Coniferous Deciduous Result: ↑ rip veg = ∆ food supply ↑ litter ↑ invert production (?) ∆ invert community comp

11. Tape et al. 2006 1949 2000 Kugururok River Climate Change Effects Terrestrial vegetation cover changes (headwaters) Active stream channels and gravel bars in 1949 are now colonized by shrubs – alder, willow, dwarf birch.

12. Spruce riparian Invertebrate biomass exported (mg dry mass·m -3 water) 0 2 4 6 Conifer Alder p < 0.05 Piccolo and Wipfli 2002 Aq. invertebrate drift density Maybeso Drainage Alder riparian Result: ↑ deciduous veg = ↑ food for aq consumers

13. Sturm et al. 2005 Climate Change Effects Nutrient loading – from land Result (?): ↑ nutrients (N + P) = ↑ aq production ∆ invert composition Hobbie et al. 1999 Benstead et al. 2005 Stream nutrient addition studies led to higher aq production in Kuparuk studies.

14. Bilby et al. 1996, 1998 Heintz 2004 Wipfli et al. 1998, 2003, 2004 Anadromous fish runs enrich streams with nutrients Shown to increase aquatic productivity in Alaska & the PNW ↑ nutrients (N + P) = ↑ aq production (all trophic levels) ↑ fish growth rates, production, lipid levels

15. Climate Change Effects Warming ocean currents Salmon distributions shift northward (Welch et al. 1998)

16. Climate Change Effects Nutrient loading – from the sea Result (?): ↑ nutrients (N + P) = ↑ aq production ∆ invert community composition

17. Summary – hypothesized climate change effects Increased temperatures = ↑ invertebrate production ∆ invertebrate community composition ∆ seasonal occurrence Terrestrial veg expansion = ↑ invertebrate abundance ∆ invertebrate community composition ∆ seasonal occurrence Nutrient loading = ↑ invertebrate production ∆ invertebrate community composition ∆ seasonal occurrence

18. Summary – hypothesized climate change effects Increased temperatures = ↑ invertebrate production ∆ invertebrate community composition ∆ seasonal occurrence Terrestrial veg expansion = ↑ invertebrate abundance ∆ invertebrate community composition ∆ seasonal occurrence Nutrient loading = ↑ invertebrate production ∆ invertebrate community composition ∆ seasonal occurrence

19. Summary – hypothesized climate change effects Increased temperatures = ↑ invertebrate production ∆ invertebrate community composition ∆ seasonal occurrence Terrestrial veg expansion = ↑ invertebrate abundance ∆ invertebrate community composition ∆ seasonal occurrence Nutrient loading = ↑ invertebrate production ∆ invertebrate community composition ∆ seasonal occurrence

20. Summary – hypothesized climate change effects Physical processes dictate biological outcomes in riverine systems Erosion & sediment deposition Riparian plant community development Leaf litter inputs Terrestrial invertebrate inputs Terrestrial ecosystem Freshwater ecosystem Elevated basal food resources for fish & other consumers

21. Questions?!?