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Horizontal transport and the distribution of nutrients in the coastal transition zone off Northern California: effects on primary production, phytoplankton biomass and species composition

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Title Horizontal transport and the distribution of nutrients in the coastal transition zone off Northern California: effects on primary production, phytoplankton biomass and species composition
Names Chavez, Francisco P. (creator)
Barber, Richard T. (creator)
Kosro, P. Michael, 1951- (creator)
Huyer, Adriana, 1945- (creator)
Ramp, Steven R. (creator)
Stanton, Timothy P. (creator)
Rojas de Mendiola, Blanca (creator)
Date Issued 1991-08-15 (iso8601)
Abstract Conductivity-temperature-depth surveys during 1988 encountered strong baroclinic jets that were evident in
acoustic Doppler current profiler and hydrographic data. During June and July 1988 a filament with high surface
nitrate, high chlorophyll, abundant populations of neritic centric diatoms, and higher rates of primary production
was evident perpendicular to the coast between Point Arena and Point Reyes. However, the high-nutrient and
phytoplankton regions were not in the baroclinic jets but were south and inshore of them. Surface water
transported offshore by the strong baroclinic jets was found to have relatively low nutrient content, suggesting
that the jets themselves do not carry significant levels of coastally upwelled, high-nutrient water to the ocean
interior. The low nutrient and salinity content of the jet suggests that the water originated several hundred
kilometers upstream. Although the jets themselves do not appear to transport significant levels of nutrients
directly from the coastal regime to the oceanic regime, dynamic processes associated with a meandering jet are
likely responsible for high surface nutrients found several hundred kilometers offshore. Processes such as
upwelling along the southern edge of the seaward jet result in significant enrichment of the coastal transition
zone and in large blooms of neritic diatoms. During 1988 the high-nutrient, high-phytoplankton filament was
present when the survey sequence began but then decayed after a month. The surface and subsurface nitrate
fields were coherent with the dynamic topography field throughout the survey sequence; however, the surface
and integrated chlorophyll fields were coherent only through the first two surveys. A decrease in phytoplankton
biomass began during the third survey coincident with physical changes which occurred in that time frame: (1)
an intensification of the undercurrent and (2) changes in the surface circulation from predominantly offshore to
predominantly alongshore. Understanding the processes responsible for the uncoupling between biology and
physics is paramount for realistic biological models of this region.
Genre Article
Identifier Chavez, F. P., Barber, R. T., Kosro, P. M., Huyer, A., Ramp, S. R., Stnaton, T. P., & Rojas de Mendiola, B. (1991). Horizontal transport and the distribution of nutrients in the coastal transition zone off Northern California: effects n primary production, phytoplankton biomass and species composition. Journal of Geophysical Research, 96(C8), 14833-14848.

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