Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 8423
Title: Influence of a coastal riverine plume on the cross-shelf variability in hydrography, zooplankton and juvenile salmon diets
Author: Richard D. Brodeur, C. A. Morgan
Publication Year: 2015
Journal: Estuaries and Coasts
Volume: 39
Pages: 1183-1198
Keywords: oceanography, zooplankton, habitat, riverine plume, feeding habits, juvenile salmon,

Riverine plumes in nearshore coastal waters are areas of enhanced production and accumulation of prey and may increase availability of food during a critical period of juvenile salmon survival and hence serve as a nursery area for these juveniles.  Physical and biological sampling was conducted along a cross–shelf transect through the Columbia River plume during May 1999.  Based on cluster analyses of physical variables, stations considered to be within the core of the plume, at 27.8–46.3 km from shore, were distinct from inshore (7.4–18.5 km) and offshore (55.6–92.7 km) stations.  Five variables (temperature at 10 m, salinity at 3 and 10 m, silicate, and chlorophyll) accounted for 92% of this difference.  Both surface neuston and subsurface plankton tows revealed differences in plankton composition at the plume core stations compared to non–plume stations.  However, stomach contents of juvenile Chinook salmon were not significantly different inside and outside the plume core.  Comparison of similarity indices showed that the stomach composition was more similar to the catch composition in the neuston than the meter net.  Fishes, decapod larvae, and hyperiid amphipods occurred in greater proportions and copepods and euphausiids in lesser proportions in the stomachs than in the plankton.  There appeared to be a distinctive plume signal, evident in both the physical environment and zooplankton resources sampled inside and outside the plume core, but the plume signature was not as evident in the salmon diets, possibly due to their higher mobility and shorter residence time within the plume. 

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Notes: This paper had received extensive review back in 2010 and I have a signed Manuscript Record and NOAA Form 25-700 for a different journal. Was not accepted at the time so this is a revised and updated version but basically the same paper.
Theme: Ecosystem approach to improve management of marine resources
Foci: Characterize ecological interactions (e.g. predation, competition, parasitism, disease, etc.) within and among species.
Characterize the interaction between marine, freshwater and terrestrial ecosystem components.