Ice Streams & Invertebrates

Matthew McClure

Winter Ecology, Mountain Research Station; 2008

Questions

• Is there invertebrate activity in winter streams?

• If so, how active are the invertebrates?

• What importance do invertebrates serve during the winter?

3 types of Invertebrates

• Macro invertebrates

• Mesofauna

• Micro invertebrates

– Nematodes, Small Arthropods, Springtails, Rotifers, Snails, Fly larvae

etc.

Ice Streams

• Flowing >0 C°

• Frozen < 0 C°

• Ice Anchors

Ice Stream Profile

Is there invertebrate activity in a winter stream?

• YES!

• How we know this– Fecal Matter (Shepard, Minshall; 1984)– Visual Observations

Winter Adaptations for Winter Stream Survival

• Freeze • Cryptobiosis• Activity• Tolerate• Migration• Die

How active are the invertebrate fauna?

• Fecal Matter Observations

Fecal Matter(Shepard, Minshall; 1984)

• Winter activity is species dependent

– Typically: Higher activity in winter for

some species

– Example: Caddis Flies

Ecological Impacts of Winter Invertebrate Activity

Activity

• Provides a large influx of nutrients in Spring

– Decomposition, wood/leaf litter

(Anderson et al., 1978)

– Fecal Matter Deposition

Non-Active Importance

• Dead Invertebrates,

Nutrient cyclers

• Frozen Invertebrates

Ready for Spring

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

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.