THE ECOLOGICAL QUESTION

How does phosphorus fertilization affect long-term community structure in an arctic stream?

ECOLOGICAL CONTENT

nutrient enrichment, limiting factor, bottom-up effects, cascade effects, herbivory, food webs, community structure, river community structure

WHAT STUDENTS DO

Students make Microsoft Excel bar graphs to assess effects of phosphorus addition on epilithic algae, epibenthic moss, mayflies, and arctic grayling fish in the Kuparuk River, in the foothills of the North Slope of Alaska. Data were taken over 15 years at the ARC LTER site at the Toolik field station. With these data, students: 1) hypothesize the influence of nutrient limitation in the community, 2) predict community response to nutrient fertilization, 3) test predictions by analyzing the long term data set, and 4) assess validity of hypotheses. In the process students appreciate the value of long-term ecological data sets.

SKILLS

Using a computer spreadsheet to make simple graphs, working in groups, oral presentation of analysis, writing a research paper, hypothesizing, analyzing, interpreting, and drawing conclusions.

ASSESSABLE OUTCOMES

Graphs from spreadsheet data, written or oral analyses, interpretations, conclusions, and hypotheses.

SOURCE

Slavik, K., Peterson, B. J., Deegan, L. A., Bowden, W. B., Hershey, A. E., Hobbie, J. E. 2004. Long-term responses of the Kuparuk River ecosystem to phosphorus fertilization. Ecology: Vol. 85, No. 4, pp. 939–954.

AUTHORS

Linda Deegan

The Ecosystems Center, Marine Biological Laboratory, Woods Hole, MA 02543, Phone: 508-289-7487, Fax: 508-457-1548, ldeegan@mbl.edu

ACKNOWLEDGMENTS

Dr. Bruce Peterson conceived the idea of adding P to the stream to investigate the long-term consequences of small changes in the availability of a limiting nutrient. The National Science Foundation funded the original research and the development of this activity through the Long-Term Ecological Research Program. Karie Slavik developed the original data set and Jonathan Benstead provided the two photographs. Charlene D'Avanzo suggested this would be an appropriate data set for TIEE and was instrumental in bringing this exercise to fruition.

CITATION

Deegan, Linda. March 2005, posting date.
Long-term Response of an Arctic River Community to Phosphorus Fertilization, Teaching Issues and Experiments in Ecology, Vol. 3: Issues: Data Set #2 [online].
http://tiee.ecoed.net/vol/v3/issues/data_sets/arc/abstract.html