Dataset: Vertical Plankton Tow - VPT
Deployment: EL021101

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)