Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Data Files
• Related Publications
• Parameters
• Instruments
• Deployments
• Project Information
• Program Information
• Funding

This project was designed to make a comparison of the effects of coastal upwelling on the population dynamics and vital rates of the euphausiids Euphausia pacifica and Thysanoessa spinifera in the Northern California Current, north and south of Cape Blanco, Oregon.

These data are part of a project which describes the population dynamics of these two GLOBEC target organisms. The nets sampled along several transect lines off the central Oregon coast  for the purpose of describing temporal variations in euphausiid abundance, recruitment, vital rates and production. A high-frequency sampling program will be supplemented with bimonthly cruises sampling along four transect lines: two off Oregon (Newport and Coos Bay) and two off northern California (Crescent City and Eureka) during GLOBEC Long-Term Observations Program (L-TOP) cruises. Data from these survey cruises will provide information on spatial variations in euphausiid biomass, numerical abundance, vital rates and production in the waters throughout the GLOBEC study region (Newport OR south to Eureka CA). The project proposed here has four objectives:

(1) determine the seasonal cycles of abundance of the two euphausiid species in relation to interannual variations in circulation, hydrography and upwelling;
(2) determine the seasonal, interannual and spatial variations in egg production rates, cohort development, and recruitment as a function of upwelling and phy toplankton blooms;
(3) examine the seasonal, interannual and spatial variations in mortality rates and production as a means to develop a better understanding of euphausiid population dynamics; and
(4) determine overwintering strategies and the role of seasonal reversals in circulation and the spring transition in redistributing euphausiids in shelf and slope waters.

All of the above data will be passed to one of the GLOBEC modelers (H. Batchelder, Univ. of California at Berkeley) who is developing an individual-based model for both euphausiid species; the proposed work is presented in the context of examining the relationship between the ecology of euphausiids and salmonid growth and survival.

The VPT data are organized on the GLOBEC server by cruise within year. The master page (Level 0) lists all of the cruises in chronological order. Clicking on a cruise will show all of the casts collected/processes from that cruise (Level 1). Clicking on a cast will bring up the Level 2 file that shows a single line with additional header information for a sample. Clicking on the sample_id (always "1" for this type of data) will display the Level 3 data, which are the actual taxonomic categories and abundances for that particular sample. Additional info about the variables are described below.

(See Hooff and Peterson, 2006)

"Zooplankton were collected using a 0.5 meter diameter, 202 micron mesh net towed verticaly from within 5 meters of the bottom (to a maximum depth of 100 m) to the surface at a rate of 30 meters per minute. A TSK flowmeter was used to monitor the amount of water filtered. The samples were preserved in a 5% buffered formalin/seawater solution." (W.T. Peterson, et al., 2002 p. 392)

"In the laboratory, the zooplankton samples were diluted and subsampled with a 1.1 ml Stempel pipette. Two to four such subsamples, about 2% of the total sample, were counted at 25-50x magnification. Copepods and Euphausiids were identified to species and developmental stage; other zooplankton were assigned to broad taxonomic groups (e.g. polychaetes, medusae, larvaceans, chaetognaths.) All euphausiids, pteropods, salps, and chaetognaths were measured. In each sample, the population density of each taxonomic group (number of individuals per cubic meter) was calculated. Copepod densities were converted to biomass estimates using dry weight/developmental-stage values found in the literature; biomasses of euphausiids, pteropods, salps, and chaetognaths were calculated from densities using length-weight regressions found in the literature." (W.T.Peterson, et al., 2002, p.392)

Program in a Nutshell

Goal: To understand the effects of climate variability and climate change on the distribution, abundance and production of marine animals (including commercially important living marine resources) in the eastern North Pacific. To embody this understanding in diagnostic and prognostic ecosystem models, capable of capturing the ecosystem response to major climatic fluctuations.

Approach: To study the effects of past and present climate variability on the population ecology and population dynamics of marine biota and living marine resources, and to use this information as a proxy for how the ecosystems of the eastern North Pacific may respond to future global climate change. The strong temporal variability in the physical and biological signals of the NEP will be used to examine the biophysical mechanisms through which zooplankton and salmon populations respond to physical forcing and biological interactions in the coastal regions of the two gyres. Annual and interannual variability will be studied directly through long-term observations and detailed process studies; variability at longer time scales will be examined through retrospective analysis of directly measured and proxy data. Coupled biophysical models of the ecosystems of these regions will be developed and tested using the process studies and data collected from the long-term observation programs, then further tested and improved by hindcasting selected retrospective data series.

U.S. GLOBEC (GLOBal ocean ECosystems dynamics) is a research program organized by oceanographers and fisheries scientists to address the question of how global climate change may affect the abundance and production of animals in the sea.

The U.S. GLOBEC Program currently had major research efforts underway in the Georges Bank / Northwest Atlantic Region, and the Northeast Pacific (with components in the California Current and in the Coastal Gulf of Alaska). U.S. GLOBEC was a major contributor to International GLOBEC efforts in the Southern Ocean and Western Antarctic Peninsula (WAP).