HR: 1330h
AN: NB33K-06    [Abstracts]
TI: Recovery of Three Arctic Stream Reaches From Experimental Nutrient Enrichment.
AU: * Green, A C
EM: agreen@mbl.edu
AF: The Ecosystems Center, Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA 02543 United States
AU: Benstead, J P
EM: jbenstead@mbl.edu
AF: The Ecosystems Center, Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA 02543 United States
AU: Deegan, L A
EM: ldeegan@mbl.edu
AF: The Ecosystems Center, Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA 02543 United States
AU: Peterson, B J
EM: peterson@mbl.edu
AF: The Ecosystems Center, Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA 02543 United States
AU: Bowden, W B
EM: breck.bowden@uvm.edu
AF: Rubenstein School of Environment & Natural Resources, University of Vermont, 304 Aiken Center, Burlington, VT 05405 United States
AU: Huryn, A D
EM: huryn@bama.ua.edu
AF: Aquatic Biology Program, University of Alabama, A122 Bevill Building, 7th Ave., Tuscaloosa, AL 35487 United States
AU: Slavik, K
EM: slavik@umich.edu
AF: University of Michigan Biological Station, 2014 Natural Science Bldg. 830 North University Ave., Ann Arbor, MI 48109 United States
AU: Hershey, A E
EM: aehershe@uncg.edu
AF: Department of Biology, University of North Carolina, 345 Bruce M. Eberhart Bldg., Greensboro, NC 27402 United States
AB: We examined multi-year patterns in community recovery from experimental low-concentration nutrient (N+P and P only) enrichment in three reaches of two Arctic tundra streams (Kuparuk River and Oksrukuyik Creek) on the North Slope of Alaska (USA). Rates of recovery varied among community components and depended on duration of enrichment (2 to 13 consecutive growing seasons). Biomass and C:P ratio of epilithic algae returned to reference levels rapidly (within 2 years), regardless of enrichment duration. Bryophyte cover, which increased greatly after long-term enrichment (>8 years), recovered to reference levels only after 7 years, when a storm scoured most remnant moss in the recovering reach. Persistence of bryophytes slowed recovery rates of insect taxa that had either been positively (e.g., Ephemerella, most chironomid taxa) or negatively (e.g., Orthocladius rivulorum) affected by this shift in dominant primary producer and its consequence for benthic habitat. Growth of Arctic grayling (adults and young-of-year), the top predator, returned to reference rates within two years. Recovery of these Arctic stream ecosystems from nutrient enrichment was consequently controlled largely by interactions between duration of enrichment and physical disturbance, mediated through physical habitat shifts caused by bryophytes.
DE: 1615 Biogeochemical processes (4805)
DE: 9810 New fields (not classifiable under other headings)
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly