Tuesday, May 27, 2008
599

Habitat template analysis of macroinvertebrate and algal communities in arctic headwater streams

Stephanie M. Parker and Alexander D. Huryn. Department of Biological Sciences, The University of Alabama, Box 870206, Tuscaloosa, AL 35487

We tested the hypothesis that substratum instability, freezing, and nutrient supply comprise the axis of a three-dimensional habitat template that is a major determinant of community structure in arctic Alaskan streams. Substratum instability, freezing, nutrient supply, and community attributes were assessed in 20 headwater streams representing five pre-determined stream types: mountain spring, tundra spring, mountain, tundra, and glacier. Substratum instability was measured directly using particles marked in situ. Thirteen streams froze, with substratum movement ranging from 0-97%, while seven did not. The latter streams showed substratum movement ranging from 0-75%. Macroinvertebrate biomass (5.7x104–7.8x104 mg m-2) and algal biovolume (3000–7050 mm3 m-2) were highest in spring and tundra spring streams, while glacier streams had the lowest macroinvertebrate biomass (3.7x102 mg m-2) and algal biovolume (679 mm3 m-2). Multidimensional scaling (MDS) analyses of macroinvertebrate biomass and algal biovolume were used to assess the three-dimensional habitat template. MDS analysis supported the hypotheses that stream types were distinct and communities were structured by three major variables: substratum instability, freezing, and nutrient supply. Additionally, macroinvertebrate communities were influenced by flood magnitude, while algal communities were not affected by freezing, but appeared to be closely correlated with solute concentrations.


Web Page: community, disturbance, arctic

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