Oregon

You need Java to see this applet.

List of euphausiids from Oregon

New Ph.D. Thesis proposal (in progress)

I am interested in studying how the population dynamic, distribution patterns (maintenance strategies), and swarming behavior of euphausiids change with physical mesoscale variations of physical properties in the Oregon upwelling system. Euphausiids are important food items of the coho salmon (Oncorhynchus kitchus) and chinook salmon (Oncorhynchus tshawytscha therefore we are interested to study the possible relation of secondary productivity of the euphausiids with the juvenile salmon in the Oregon coast. Both salmon species have been decreasing in abundance during the last two decades (see landing time series of salmon in Washington, Oregon and California region). Coho salmon abundance reached a peak in 1976 and has declined even since. Chinook salmon abundance has also generally declined since the mid 1970's althought there was a brief increase in chinook salmon abundance in late 1980's.

Euphausia pacifica Hansen is one of the main target species in our study along the Oregon upwelling system. This species lives in the subarctic and transition zones of the North Pacific and is the only northern Euphausia species.

Thysanoessa spinifera Holmes is another of the main target species in our study along the Oregon upwelling system. This species lives in the subarctic and transition zones of the North Pacific it is neritic and some times form dense day-time surface swarms attracting larger predators

Patchiness of zooplankton is a feature of central importance in marine ecosystems. In the Oregon upwelling system, aggregations of krill (mainly Euphausia pacifica and Thysanoessa spinifera) are of particular interest because they are the preferred prey of some commercial fish populations in this region (e.g. hake and coho salmon). The distribution and dynamics of such aggregations are critical to determining the transformation of organic matter (e.g. carbon flux) and the fate of populations in the sea. This aggregation is especially important in the mesoscale and sub-mesoscale domains, where patchiness is most strongly expressed. If the means are lacking to predict patch dynamics, then so are the means to adequately predict carbon flux and population dynamics at these scales. Traditional models of zooplankton patch dynamics generally treat animals as Lagrangian particles whose aggregations are determined solely by processes of advection and diffusion. This approach ignores behavior induced by biotic and abiotic signals and manifested as purposeful motion - motion that clearly is not governed by advection or diffusion. Using hydroacoustic observations along with comprehensive net sampling, I expect to study swarming behavior, and inshore-offshore distribution of these organisms in the upwelling area. Additionally, I plan to investigate how spatial and temporal variability in physical-biological features affects the development (growth), fecundity and survival of Euphausia pacifica and Thysanoessa spinifera. These parameters are important to estimate secondary productivity. I contend that spawning variability and regional differences in food availability and temperature are significant forces controlling larval mortality, demography, and subsequent juvenile and adult recruitment.

I am part of a research team that is involved with the research projects recently approved by GLOBEC U.S.:

Dr. William Peterson (principal investigator). 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 Cape Blanco, OR.

Dr. William Peterson (principal investigator). Long-term changes in hydrography and zooplankton in the northern California Current waters of the Oregon coast

Currently I'm working some samples collected every month from the Newport Hydrographic line during 1971-1972. The main goal is to know the dynamic population, production and zonation (inshore-offshore) of the main euphausiids. The most abundant species were Euphausia pacifica, Thysanoessa spinifera, T. longipes, and Nematoscelis difficilis.

Link to others sites related with the proyect

Satellite data for the Oregon and Washington area COAS-OSU

Mesoscale-II cruise on board the
R/V New Horizon and R/V Wecoma

U.S. GLOBEC

North East Pacific U.S. GLOBEC

NEW link Directory of researchers from the
North East Pacific U.S. GLOBEC