Search results | Digital Commons of Moss Landing Marine Laboratories

Title: A rosette system for the collection of trace metal clean seawater,
Description: We designed a large-volume rosette sampler for collecting seawater with minimal trace metal contamination. The system uses eight modified 30-liter Go-Flo bottles secured to a Nylon II-coated stainless steel frame. The instrument is deployed with a dedicated winch with polyurethane-coated, three-conductor Kevlar hydroline. A prototype was used as part of the U.S. JGOFS Equatorial Pacific sampling program during spring and fall 1992. A redesigned model was used during the 1993 IronEx experiments and is currently being deployed in the Arabian Sea. The results of trace metal analyses collected on these cruises indicate that samples recovered are comparable to current single Go-Flo casts., Cited By (since 1996):28, CODEN: LIOCA, , , Oceanography, Downloaded from: www.aslo.org/lo/toc/vol_41/issue_6/1367.pdf (23 June 2014).
Author: Hunter, Gordon, Fitzwater, Coale
Date: 1996-01-01T00:00:00Z

Title: Biological response to iron fertilization in the eastern equatorial Pacific (IronEx II). I. Microplankton community abundances and biomass,
Description: During the IronEx II experiment in the eastern equatorial Pacific (May to June 1995), the response of the microplankton community to mesoscale iron fertilization was followed using a combination of marker-pigment, microscopical and flow cytometric techniques. Phytoplankton standing stock bloomed dramatically over a period of 6 d following 3 iron additions of 2 and 1 nM, respectively. Carbon biomass in the patch increased by a factor of 4, chlorophyll a by about a factor of 16 and diatoms by > 70-fold relative to contemporaneous levels in the ambient community. The bloom then plateaued sharply and remained at a more or less constant level for 4 d, despite the addition of more iron (1 nM) and physiological indices (low C:chl a ratio and elevated photochemical quantum efficiency) suggesting that the cells were healthy and growing rapidly. Relatively large pennate diatoms (Nitzschia spp., median length 20 to 24 μm) dominated the patch bloom, with smaller pennate species and centric diatoms declining in relative importance. Heterotrophic bacteria increased at a slow rate (0.08 d -1) for > 10 d during the experiment, as did heterotrophic nanoflagellates. There were also indications of enhanced cell size, cellular pigment content and possibly growth rates of small phytoplankton. Nonetheless, little difference was observed between the ambient community and the peak patch bloom with respect to the size composition of auto- and heterotrophic populations < 10 μm in cell size. The relative constancy of the smaller size fractions, the sharp curtailment of net growth of the bloom after 6 d, and > 3-fold increase in large heterotrophic dinoflagellates and ciliates suggest that protistan grazers may have played an active role in controlling the phytoplankton response to increased iron availability., , , ,
Author: Landry, Ondrusek, Tanner, Brown, Constantinou, Bidigare, Coale, Fitzwater
Date: 2000-01-01T00:00:00Z

Title: Iron deficiency and phytoplankton growth in the equatorial Pacific,
Description: Several experiments were conducted in the equatorial Pacific at 140°W during the Joint Global Ocean Flux Study, equatorial Pacific, 1992 Time-series I (TS-I, 23 March-9 April). Time-series II (TS-II, 2-20 October) and FeLINE II cruises (10 March-14 April), to investigate the effects of added Fe on phytoplankton communities. Seven series of deckboard iron-enrichment experiments were performed, with levels of added Fe ranging from 0.13 to 1000 nM. Time-course measurements included nutrients, chlorophyll a and HPLC pigments. Results of these experiments showed that subnanomolar (sub-nM) additions of Fe increased net community specific growth rates, with resultant chlorophyll a increases and nutrient decreases. Community growth rates followed Michaelis Menten type kinetics resulting in maximum rates of 0.99 doublings per day and a half-saturation constant of 0.12 nM iron. The dominant group responding to iron enrichment was diatoms., Cited By (since 1996):62, CODEN: DSROE, ,
Author: Fitzwater, Coale, Gordon, Johnson, Ondrusek
Date: 1996-01-01T00:00:00Z

Title: IronEx-I, an in situ iron-enrichment experiment,
Description: An in situ iron-enrichment experiment near the Galapagos Islands was performed in October 1993. Here we report the theoretical and practical considerations of creating such a patch of iron-enriched surface water, as well as the strategies employed for the detection of the patch and the biological and chemical signals which developed, in an area dominated by advective processes. Physical and chemical models were used to predict the speciation, solubility, and the final concentration of iron in surface waters injected with acidic iron sulfate. A trial injection off the California coast in which 800 L of a 0.5 M FeSO4 were introduced into the ship's wake over a 1.5 km2 area, was used to test these predictions. Iron concentrations were determined continually onboard during the initial experiment as the ship steamed in transects through the enriched patch. The results indicate excellent spatial agreement with model predictions and final concentrations that were consistent with the chemical model. However, the use of a Cartesian coordinate system during rejection resulted in an extremely compressed, heterogeneous patch. Results from this preliminary experiment were then applied towards the development and implementation of the first open ocean iron enrichment experiment (IronEx I) near the Galapagos Islands in October 1993. The development and results of these methodologies are presented. In the IronEx I equatorial experiment, a Lagrangian coordinate system was established using a drogued buoy (equipped with GPS and packet radio) and the iron-enriched area (64 km2 containing 443 kg of Fe) was tagged with the inert chemical tracer sulfurhexafluoride (SF6). This strategy resulted in a fairly rectangular, homogeneous enriched patch initially detectable by both Fe and SF6 determination. Shipboard analysis and airborne observations confirmed good spatial agreement between the Lagrangian drifter and the biological and chemical signatures in the patch. Biological and chemical sampling of the enriched area showed an increase in chlorophyll, primary production, biomass and photosynthetic energy conversion efficiency relative to waters outside the patch, supporting the hypothesis that iron limits phytoplankton growth and biomass in a 'bottom up' manner in this area. The ability to create a coherent patch and track it over time led to this first open-ocean test of the iron hypothesis., Cited By (since 1996):42, CODEN: DSROE, ,
Author: Coale, Johnson, Fitzwater, Blain, Stanton, Coley
Date: 1998-01-01T00:00:00Z

Title: Southern Ocean Iron Enrichment Experiment,
Description: The availability of iron is known to exert a controlling influence on biological productivity in surface waters over large areas of the ocean and may have been an important factor in the variation of the concentration of atmospheric carbon dioxide over glacial cycles. The effect of iron in the Southern Ocean is particularly important because of its large area and abundant nitrate, yet iron-enhanced growth of phytoplankton may be differentially expressed between waters with high silicic acid in the south and low silicic acid in the north, where diatom growth may be limited by both silicic acid and iron. Two mesoscale experiments, designed to investigate the effects of iron enrichment in regions with high and low concentrations of silicic acid, were performed in the Southern Ocean. These experiments demonstrate iron's pivotal role in controlling carbon uptake and regulating atmospheric partial pressure of carbon dioxide., Cited By (since 1996):316, Oceanography, CODEN: SCIEA, ,
Author: Coale, Johnson, Chavez, Buesseler, Barber, Brzezinski, Cochlan, Millero, Falkowski, Bauer, Wanninkhof, Kudela, Altabet, Hales, Takahashi, Landry, Bidigare, Wang, Chase, Strutton, Friederich, Gorbunov, Lance, Hilting, Hiscock, Demarest, Hiscock, Sullivan, Tanner, Gordon, Hunter, Elrod, Fitzwater, Jones, Tozzi, Koblizek, Roberts, Herndon, Brewster, Ladizinsky, Smith, Cooper, Timothy, Brown, Selph, Sheridan, Twining, Johnson
Date: 2004-01-01T00:00:00Z

Title: Developing standards for dissolved iron in seawater
Description: Cited By (since 1996):114
Author: Johnson, Boyle, Bruland, Coale, Measures, Moffett, Aguilar-Islas, Barbeau, Bergquist, Bowie, Buck, Cai, Chase, Cullen, Doi, Elrod, Fitzwater, Gordon, King, Laan, Laglera-Baquer, Landing, Lohan, Mendez, Milne, Obata, Ossiander, Plant, Sarthou, Sedwick, Smith, Sohst, Tanner, Van den Berg, Wu
Date: 2007-01-01T00:00:00Z

Title: A massive phytoplankton bloom induced by an ecosystem-scale iron fertilization experiment in the equatorial Pacific Ocean
Description: The seeding of an expanse of surface waters in the equatorial Pacific Ocean with low concentrations of dissolved iron triggered a massive phytoplankton bloom which consumed large quantities of carbon dioxide and nitrate that these microscopic plants cannot fully utilize under natural conditions. These and other observations provide unequivocal support for the hypothesis that phytoplankton growth in this oceanic region is limited by iron bioavailability., Cited By (since 1996):930, Oceanography
Author: Coale, Johnson, Fitzwater, Gordon, Tanner, Chavez, Ferioli, Sakamoto, Rogers, Millero, Steinberg, Nightingale, Cooper, Cochlan, Landry, Constantinou, Rollwagen, Trasvina, Kudela
Date: 1996-01-01T00:00:00Z

Title: Testing the iron hypothesis in ecosystems of the equatorial Pacific Ocean,
Description: The idea that iron might limit phytoplankton growth in large regions of the ocean has been tested by enriching an area of 64 km 2 in the open equatorial Pacific Ocean with iron. This resulted in a doubling of plant biomass, a threefold increase in chlorophyll and a fourfold increase in plant production. Similar increases were found in a chlorophyll-rich plume down-stream of the Galapagos Islands, which was naturaly enriched in iron. These findings indicate that iron limitation can control rates of phytoplankton productivity and biomass in the ocean., Cited By (since 1996):749, Oceanography, CODEN: NATUA, ,
Author: Martin, Coale, Johnson, Fitzwater, Gordon, Tanner, Hunter, Elrod, Nowicki, Coley, Barber, Lindley, Watson, Van Scoy, Law, Liddicoat, Ling, Stanton, Stockel, Collins, Anderson, Bidigare, Ondrusek, Latasa, Millero, Lee, Yao, Zhang, Friederich, Sakamoto, Chavez, Buck, Kolber, Greene, Falkowski, Chisholm, Hoge, Swift, Yungel, Turner, Nightingale, Hatton, Liss, Tindale
Date: 1994-01-01T00:00:00Z

Title: Effect of iron limitation on the cadmium to phosphorus ratio of natural phytoplankton assemblages from the Southern Ocean,
Description: There is considerable interest in the biogeochemical cycling of cadmium (Cd) and phosphate (PO 4) in surface waters, driven in part by the ongoing development of a paleonutrient proxy that utilizes Cd preserved in fossil planktonic foraminifera to determine past PO 4 utilization efficiencies in ocean surface waters. The present article reports the results of a field study into the effects of Fe limitation on the Cd:P composition of natural assemblages of marine phytoplankton in the Antarctic Zone of the Pacific sector of the Southern Ocean. Iron enrichment to shipboard incubation bottles led to increases in community growth rate and final biomass. After 10.7 d of incubation, the climax community was dominated by large diatoms of the genus Fragillariopsis, Pseudonitzschia, and Nitzschia. Direct measurements of phytoplankton metal : P ratios from controlled shipboard experiments indicate that Cd:P, Co:P, and Zn:P ratios decreased from control values with increasing initial dissolved Fe concentrations in the incubation bottles, by factors of ∼2-10 at highest Fe additions. We suggest that the effect of Fe limitation on resident diatoms is to decrease growth rate, leading to elevated cellular Cd content. The dissolved Cd:P ratio in iron-limited surface waters of the Southern Ocean may, therefore, respond to the supply of Fe to the resident phytoplankton community, which has implications for the developing paleonutrient proxy. We suggest that the biological uptake of Cd and P is independent of the dissolved Cd:PO 4 ratio. As a consequence, the results argue against the use of empirical Rayleigh fractionation models or models with fixed phytoplankton uptake ratios to account for regional variability in surface water dissolved Cd:PO 4., Cited By (since 1996):33, Oceanography, CODEN: LIOCA, ,
Author: Cullen, Chase, Coale, Fitzwater, Sherrell
Date: 2003-01-01T00:00:00Z

Title: Control of community growth and export production by upwelled iron in the equatorial Pacific Ocean
Description: The iron hypothesis states that phytoplankton growth and biomass are limited by low concentrations of available iron in large regions of the world's oceans where other plant nutrients are abundant. Such limitation has been demonstrated by experiments in which iron has been added to both enclosed and in situ (un-enclosed) phytoplankton populations. A corollary of the iron hypothesis is that most 'new' iron is supplied by atmospheric deposition, and it has been suggested that changes in the deposition rates of iron-bearing dust have led to changes in biological productivity and, consequently, global climate. Here we report surface-water measurements in the equatorial Pacific Ocean which show that the main iron source to equatorial waters at 140°W is from upwelling waters. Shipboard in vitro experiments indicate that sub-nanomolar increases in iron concentrations can cause substantial increases in carbon export to deeper waters in this region. These findings demonstrate that equatorial biological production is controlled not solely by atmospheric iron deposition, but also by processes which influence the rate of upwelling and the iron concentration in upwelled water., Cited By (since 1996):221 Seaweeds, CODEN: NATUA
Author: Coale, Fitzwater, Gordon, Johnson, Barber
Date: 1996-01-01T00:00:00Z