Salmon contributions to dissolved organic matter and nutrient loads in a coastal stream in Southeastern Alaska

HR: 0800h
AN: H31B-1307 [Abstracts]
TI: Salmon contributions to dissolved organic matter and nutrient loads in a coastal stream in Southeastern Alaska
AU: * Hood, E
EM: eran.hood@uas.alaska.edu
AF: Environmental Science Program University of Alaska Southeast, 11120 Glacier Highway, Juneau, AK 99801 United States
AU: Fellman, J B
EM: fsjbf6@uaf.edu
AF: USDA Forest Service Pacific Northwest Research Station, 2770 Sherwood Lane, Juneau, AK 99801 United States
AU: Edwards, R T
EM: rtedwards@fs.fed.us
AF: USDA Forest Service Pacific Northwest Research Station, 2770 Sherwood Lane, Juneau, AK 99801 United States
AB: In southeastern Alaska, spawning salmon can have a substantial effect on the water quality of coastal watersheds because salmon move large quantities of marine nutrients into terrestrial freshwater streams. We are measuring the effects of salmon on loads of inorganic nutrients (nitrogen and phosphorus) and dissolved organic matter (DOM) in Peterson Creek near Juneau, Alaska. Peterson Creek receives sizable runs of pink (Oncorhynchus gorbushca) and chum (Oncorhynchus keta) salmon during the late summer (mid-August through mid-September). To test the effects of salmon on water quality, samples were collected above and below a barrier waterfall on Peterson Creek. During salmon spawning, concentrations of ammonium (NH₄⁺) were up to two orders of magnitude higher at the downstream salmon-influenced site, while soluble reactive phosphorus (SRP) increased by more than an order of magnitude at the downstream site. For the entire salmon spawning period, concentrations of NH₄⁺, SRP, and dissolved organic carbon (DOC) were significantly higher at the downstream site compared to the upstream site, however nitrate (NO₃^-) concentrations were not significantly different between sites. Characterization of DOC samples using fluorescence spectroscopy showed that the DOC leached from salmon had a large protein component compared to DOC at the upstream site which was dominated by humic material. These results suggest that salmon provide a pulse of inorganic N and P as well as labile DOC to surface waters during the spawning period. Concurrent measurements of discharge will allow us to assess the importance of salmon-derived nutrients in the seasonal nutrient budget of Peterson Creek.
DE: 1806 Chemistry of fresh water
DE: 1813 Eco-hydrology
DE: 1871 Surface water quality
SC: Hydrology [H]
MN: Fall Meeting 2005