1. Ice Streams & Invertebrates Matthew McClure Winter Ecology, Mountain Research Station; 2008

2. Questions Is there invertebrate activity in winter streams? If so, how active are the invertebrates? What importance do invertebrates serve during the winter?

3. 3 types of Invertebrates Macro invertebrates Mesofauna Micro invertebrates –Nematodes, Small Arthropods, Springtails, Rotifers, Snails, Fly larvae etc.

4. Ice Streams Flowing >0 C° Frozen < 0 C° Ice Anchors

5. Ice Stream Profile

6. Is there invertebrate activity in a winter stream? YES! How we know this –Fecal Matter (Shepard, Minshall; 1984) –Visual Observations

7. Winter Adaptations for Winter Stream Survival Freeze Cryptobiosis Activity Tolerate Migration Die

8. How active are the invertebrate fauna? Fecal Matter Observations

9. Fecal Matter (Shepard, Minshall; 1984) Winter activity is species dependent –Typically: Higher activity in winter for some species –Example: Caddis Flies

10. Ecological Impacts of Winter Invertebrate Activity

11. Activity Provides a large influx of nutrients in Spring –Decomposition, wood/leaf litter (Anderson et al., 1978) –Fecal Matter Deposition

12. Non-Active Importance Dead Invertebrates, Nutrient cyclers Frozen Invertebrates Ready for Spring

13. Conclusions Yes, Invertebrates are Active During the Winter Some Species Maintain High Levels of Activity During Winter Activity and Inactivity Play Important Roles in the Ecological Function of Streams During the Winter with Relations to Nutrient Loading for Spring and Summer Months

14. References Anderson N.H., J.R. Sedell, L.M. Roberts and F.J. Triska. 1978. The role of aquatic invertebrates in processing of wood debris in coniferous forest streams. American Midland Naturalist 100:64-82. Crowe J.H. 1971. Anhydrobiosis: An unsolved problem. The American Naturalist 105:563-573. Lillehammer A. and J.E. Brittain. 1978. The invertebrate fauna of the streams in Ovre Heimdalen. Holartic 1:271-276. Olsson, T.I. 1981. Overwintering of benthic macroinvertebrates in ice and frozen sediment in a north Swedish river. Holarctic Ecology 4:161-166. Oswood M.W., L.K. Miller, and J.G. Irons III, “Overwintering of Freshwater Benthic Macroinvertebrates,” in P. Marchand Life in the Cold (Hanover: University Press of New England, 1996), 148-149. Pace M.L. and J.D. Orcutt. 1981. The relative importance of protozoans, rotifers, and crustaceans in a freshwater zooplankton community. Limnology and Oceanography 26:822-830. Pennington W. 1941. The control of the numbers of freshwater phytoplankton by small invertebrate animals. The Journal of Ecology 29:209-211. Pace M.L. and J.D. Orcutt. 1981. The relative importance of protozoans, rotifers, and crustaceans in a freshwater zooplankton community. Limnology and Oceanography 26:822-830. Shepard R.B. and G.W. Minshall. 1984. Role of benthic insect feces in a Rocky Mountain stream: Fecal production and support of consumer growth. Holartic 7:119-127.