Index Catalog // ScholarsArchive@OSU

Role of Trichodesmium spp. in the productivity of the subtropical North Pacific Ocean

Creator:: Letelier, Ricardo M. and Karl, David M.
Abstract:: The concentrations of filamentous diazotroph Trichodesmium spp., present as free trichomes and in colonial assemblages, were measured at approximately monthly intervals at Stn ALOHA (22°45'N, 158°00'W) between October 1989 and December 1992. The average abundance of filaments in the upper 45 m of the water column was highly variable ranging...
Resource Type:: Article
Full Text:: subtropical North Pacific Ocean Ricardo M. L e t e l i e r l . * , David M. ~ a r l ~ ' co l lege of

Trichodesmium spp. physiology and nutrient fluxes in the North Pacific subtropical gyre

Creator:: Letelier, Ricardo M. and Karl, David M.
Abstract:: The potential role of the diazotrophic cyanobacterium Trichodesmium spp. In nitrogen and phosphorus dynamics of the euphotic zone of the North Pacific subtropical gyre was investigated as one component of the Hawaii Ocean Time-series (HOT) program. Experiments were conducted with natural samples collected at Stn ALOHA (22° 45’ N, 158°...
Resource Type:: Article

Phytoplankton fluorescence and survival below the euphotic zone in the California current system

Creator:: Murphy, Alice M.
Resource Type:: Masters Thesis
Full Text:: , Tim Cowles. Thanks also to my committee members, Ricardo Letelier, Dan Shafer, and Jeriy Heidel

Light driven seasonal patterns of chlorophyll and nitrate in the lower euphotic zone of the North Pacific Subtropical Gyre

Creator:: Letelier, Ricardo M., Karl, David M., Abbott, Mark R., and Bidigare, Robert R.
Abstract:: The euphotic zone below the deep chlorophyll maximum layer (DCML) at Station ALOHA (a long-term oligotrophic habitat assessment; 22º45′N, 158º00′W) transects the nearly permanently stratified upper thermocline. Hence, seasonal changes in solar radiation control the balance between photosynthesis and respiration in this lightlimited region. Combining profiles of radiance reflectance, algal...
Resource Type:: Article
Full Text:: Letelier, Ricardo M., David M. Karl, Mark R. Abbott, and Robert R

The role of dissolved organic matter release in the productivity of the oligotrophic North Pacific Ocean

Creator:: Karl, David M., Hebel, Dale V., Björkman, K., and Letelier, Ricardo M.
Abstract:: Based on a long-term set of observations and measurements at a station in the subtropical North Pacific Ocean, it now appears that contemporaneous rates of primary production in low-nutrient open ocean regions and perhaps in the ocean as a whole may be greater than had been considered in field studies...
Resource Type:: Article
Full Text:: KARL, DAVID M., DALE V. HEBEL, K. BJÖRKMAN, AND R. M. LETELIER

Chlorophyll natural fluorescence response to upwelling events in the Southern Ocean

Creator:: Letelier, Ricardo M., Abbott, Mark R., and Karl, David M.
Abstract:: Variability of solar-induced (natural) fluorescence and chlorophyll were measured on scales of hours to weeks in the upper layer of a cyclonic eddy located south of the Antarctic Polar Front using a free-floating drifter. The fluorescence signal was analyzed both in terms of chlorophyll concentration and as an indicator of...
Resource Type:: Article

Modeling carbohydrate ballasting by Trichodesmium spp.

Creator:: White, Angelicque E., Spitz, Yvette H., and Letelier, Ricardo M.
Abstract:: We report the development of a numerical model simulating vertical movement of the cyanobacterium Trichodesmium spp. Given a range of physiological parameters derived from the literature, resultant model solutions allow us to explore the ecological significance of vertical migration by Trichodesmium colonies in a stratified oligotrophic oceanic system such as...
Resource Type:: Article
Full Text:: carbohydrate ballasting by Trichodesmium spp. Angelicque E. White*, Yvette H. Spitz, Ricardo M. Letelier

Autonomous observations of in vivo fluorescence and particle backscattering in an oceanic oxygen minimum zone

Creator:: Whitmire, Amanda L., Letelier, Ricardo M., Villagran, Victor, and Ulloa, Osvaldo
Abstract:: The eastern South Pacific (ESP) oxygen minimum zone (OMZ) is a permanent hydrographic feature located directly off the coasts of northern Chile and Peru. The ESP OMZ reaches from coastal waters out to thousands of kilometers offshore, and can extend from the near surface to depths greater than 700 m....
Resource Type:: Article
Full Text:: particle backscattering in an oceanic oxygen minimum zone A. L. Whitmire,1,* R. M. Letelier,1 V

Analysis of a Method to Estimate Chlorophyll-a Concentration from Irradiance Measurements at Varying Depths

Creator:: Nahorniak, Jasmine S., Abbott, Mark R., Letelier, Ricardo M., and Pegau, W. Scott
Abstract:: A model to estimate chlorophyll-a concentration and yellow substance absorption at 440 nm from irradiance measurements made at varying depths is examined. The derivation of the model, requiring irradiance measurements at three wavebands, is presented and tested on data collected in oligotrophic (with low chlorophyll concentrations) waters and in coastal...
Resource Type:: Article
Full Text:: Concentration from Irradiance Measurements at Varying Depths JASMINE S. NAHORNIAK, MARK R. ABBOTT, RICARDO M

Summer surface waters in the Gulf of California: Prime habitat for biological N₂ fixation

Creator:: White, Angelicque E., Prahl, Fredrick G., Letelier, Ricardo M., and Popp, Brian N.
Abstract:: We report significant rates of dinitrogen (N₂) fixation in the central basins of the Gulf of California (GC) during July–August 2005. Mixing model estimates based upon δ¹⁵N values of particulate matter in the surface mixed layer indicate that N₂ fixation provides as much as 35% to 48% of the phytoplankton-based...
Resource Type:: Article
Full Text:: : Prime habitat for biological N2 fixation Angelicque E. White,1 Fredrick G. Prahl,1 Ricardo M. Letelier

ScholarsArchive@OSU

Role of Trichodesmium spp. in the productivity of the subtropical North Pacific Ocean

Trichodesmium spp. physiology and nutrient fluxes in the North Pacific subtropical gyre

Phytoplankton fluorescence and survival below the euphotic zone in the California current system

Light driven seasonal patterns of chlorophyll and nitrate in the lower euphotic zone of the North Pacific Subtropical Gyre

The role of dissolved organic matter release in the productivity of the oligotrophic North Pacific Ocean

Chlorophyll natural fluorescence response to upwelling events in the Southern Ocean

Modeling carbohydrate ballasting by Trichodesmium spp.

Autonomous observations of in vivo fluorescence and particle backscattering in an oceanic oxygen minimum zone

Analysis of a Method to Estimate Chlorophyll-a Concentration from Irradiance Measurements at Varying Depths

Summer surface waters in the Gulf of California: Prime habitat for biological N₂ fixation

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