Master Dataset for Elwha Carcass Addition Experiment - Elwha River salmon carcass addition experiment

Dam removal and other fish-barrier removal projects in western North America are assumed to boost freshwater productivity via the transport of marine-derived nutrients from recolonizing Pacific salmon (Oncorhynchus spp). In anticipation of the removal of two hydroelectric dams on the Elwha River in Washington State, we tested this hypothesis with a salmon carcass addition experiment. Our study was designed to examine how background nutrient dynamics and benthic foodwebs vary seasonally, and how these features respond to salmon subsidies. We conducted our experiment in six side channels of the Elwha River, each with a spatially paired reference and treatment reach. Each reach was sampled on multiple occasions from October 2007 to August 2008, before and after carcass placement. We evaluated nutrient limitation status, measured water chemistry, periphyton, benthic invertebrates, and juvenile rainbow trout (O. mykiss) response, and traced salmon-derived nutrient uptake using stable isotopes. Outside of winter, algal accrual was limited by both nitrogen and phosphorous and remained so even in the presence of salmon carcasses. One month after salmon addition, dissolved inorganic nitrogen levels doubled in treatment reaches. Two months after addition, benthic algal accrual was significantly elevated. We detected no changes in invertebrate or fish metrics, with the exception of 15N enrichment. Natural seasonal variability was greater than salmon effects for the majority of our response metrics. Yet seasonality and synchronicity of nutrient supply and demand are often overlooked in nutrient enhancement studies. Timing and magnitude of salmon-derived nitrogen uptake suggest that uptake of dissolved nutrients were favored over direct consumption of carcasses. The highest proportion of salmon-derived nitrogen was incorporated by herbivores (18–30%) and peaked 1–2 months after carcass addition. Peak nitrogen enrichment in predators (11–16%) occurred 2–3 months after addition. All taxa returned to background d15N levels by 7 months. Since this study was conducted, both dams on the Elwha River were removed over 2011-2014 to open over 90% of the basin to anadromous fishes. We anticipate that as the full portfolio of salmon species expand through the basin, nutrient supply and demand will become more balanced and positive feedback loops of reciprocal nutrient transfer reinforced.

All datasets related to Elwha River carcass addition experiment. Includes physical habitat, chemical, and biological data.

Raw/field data, Laboratory data

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Subject to Public Access to Research Results (PARR): Yes

Presentation: Transfer of marine-derived salmon nutrients to freshwater food webs: predicted response of primary and secondary producers to dam removal on the Elwha River (Washington state), USA. Talk given at the 5th World Fisheries Congress, Yokohoma, Japan

Presentation: Effects of salmon carcasses on riverine food webs in experimental field study on the Elwha River. Talk given at 81st Annual Meeting of the Northwest Scientific Association, Seattle, WA

At this time, contact the Data Manager for information on obtaining access to this data set. In the near future, the NWFSC will strive to provide all non-sensitive data resources as a web service in order to meet the NOAA Data Access Policy Directive (https://nosc.noaa.gov/EDMC/PD.DA.php).

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Spreadsheet

Medium

All laboratory samples checked against blanks and duplicates. These data were collected and processed in accordance with established protocols and best practices under the direction of the project’s Principal Investigator. Contact the dataset Data Manager for full QA/QC methodology.

No Delay

The Northwest Fisheries Science Center facilitates backup and recovery of all data and IT components which are managed by IT Operations through the capture of static (point-in-time) backup data to physical media. Once data is captured to physical media (every 1-3 days), a duplicate is made and routinely (weekly) transported to an offsite archive facility where it is maintained throughout the data's applicable life-cycle.

Invertebrates identified and enumerated under microscopy, chlorophyll samples analyzed by fluormeter, isotope samples analyzed in mass spec