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Title: Larval settlement can explain the adult distribution of Mytilus californianus Conrad but not of M. galloprovincialis Lamarck or M. trossulus Gould in Moss Landing, central California,
Description: We investigated the spatial distribution of adult and newly settled mussels (Mytilus galloprovincialis Lamarck, Mytilus trossulus Gould and Mytilus californianus Conrad) on the shore at Moss Landing, California to test the hypothesis that adult distributions are a result of settlement patterns. Adult M. californianus were most abundant on a wave-exposed rocky jetty and adults of Blue mussels (M. trossulus and M. galloprovincialis) were more abundant inside the protected Moss Landing harbor. Using taxon-specific polymerase chain reactions, we monitored recruitment during continuous 1-2 week intervals on fibrous scrubbing pads for 12 months in 2002-2003. All mussel species settled in greatest numbers on the exposed jetty, and Blue mussels settled in greater numbers there than did M. californianus. Because Blue mussels settled abundantly where their adults were rare, post-settlement mortality appeared to be the strongest influence on adult distribution. In contrast, M. californianus settled mostly in their adult habitat., Cited By (since 1996):13, CODEN: JEMBA, ,
Author: Johnson, Geller
Date: 2006-01-01T00:00:00Z

Title: The flux of iron from continental shelf sediments: A missing source for global budgets
Description: The flux of dissolved iron from sediments to the water column was measured with flux chambers along the California coast over a five-year period. High fluxes were observed from sediments on the continental shelf. The measured fluxes were an average of 75 times larger than flux values derived from pore-water iron gradients. The iron flux was significantly correlated with the oxidation of organic matter, which allows an extrapolation to the global shelf. The input from shelf sediments is at least as significant as the global input of dissolved iron from aerosols, which has been presumed to be the dominant external iron source. Evidence of this input is seen 100’s of kilometers offshore where it can enable the high productivity of broad coastal regions seen in satellite images.
Author: Elrod, Berelson, Coale, Johnson

Title: Organic matter diagenesis in the sediments of the San Pedro Shelf along a transect affected by sewage effluent,
Description: A study was conducted to examine the rate of organic matter degradation within the sediments adjacent to the Whites Point Los Angeles County sewage outfall system on the San Pedro Shelf. Benthic chamber deployments were made at three stations in a transect away from the outfall pipe during three cruise periods (October 1990, February and October 1991). The fluxes of phosphate, silicate and radon-222 showed the most significant difference (factor of 3) between stations proximal and distal to the sewage effluent outfall pipe; the fluxes of nitrate, ammonia, alkalinity and TCO2 showed some gradient (a factor of 1.5-2) and the uptake of oxygen showed no variability between sites. Carbon oxidation in these sediments is driven primarily by net oxygen consumption and secondarily by net sulfate reduction. Net sulfate reduction accounts for about 30% of the carbon oxidation near the outfall pipe and 10-15% at the distal sites. Measurements of radon-222 fluxes and radon emanation rates from sediments indicate that the intensity of bio-irrigation is greater by a factor of 2 at sites away from the outfall pipe, but also shows that bio-irrigation does take place at the site adjacent to the pipe. The total amount of particulate organic carbon (POC) oxidized in the sediments around the outfall is ∼2 × 107 g C/d. An estimate of carbon burial in this region is 4 × 107 g C/d. The outfall system could supply ∼3 × 107 g C/d of which 12-20% is estimated to have been deposited in the region. Hence, effluent-derived POC, although it may be a part of the total organic carbon pool undergoing diagenesis and burial on the sea floor, is not likely the only source of carbon to this system. Primary productivity in the surface ocean could supply 9-13 × 107 g C/d to the sea floor. A balanced carbon budget requires that half the primary production is exported to the sea floor, although this budget does not account for other sources of POC to the region. © 2002 Elsevier Science Ltd. All rights reserved., Cited By (since 1996):13, CODEN: CSHRD, ,
Author: Berelson, Johnson, Coale, Li
Date: 2002-01-01T00:00:00Z

Title: Iron distributions in the equatorial Pacific: Implications for new production,
Description: Several recent studies have shown that phytoplankton growth rate and production at 0°, 140°W is physiologically limited by iron. Therefore, changes in iron supply to the euphotic zone will result in variations in phytoplankton growth. We show that the flux of iron to this region is dominated by upwelling of the iron-rich Equatorial Undercurrent waters. Variations in the depth and strength of upwelling and changes in iron concentrations at the base of the euphotic zone will account for variations in primary and new production in this region. We determined dissolved and particulate iron profiles for the upper water column of the eastern equatorial Pacific including a vertical section from 9°N to 3°S along 140°W. One of the more prominent features of the section was a peak in dissolved and particulate iron associated with the Equatorial Undercurrent. The possible lithogenic origin of this iron is substantiated by the vertical section of particulate aluminum and manganese, which is consistent with a shallow hydrothermal source in the western equatorial Pacific. A simple one-dimensional model was used to calculate iron fluxes into the euphotic zone at the equator. Upwelling rates and dissolved iron concentrations were coupled to estimate the upwelling iron flux at 120 m (0.1% light level). Diffusive and atmospheric inputs of iron were also considered but were less significant than the upwelling flux. Iron-based potential new production was estimated to be 10-82 mmol C m-2 d-1 with C: Fe ratios of 100,000500,000: 1. In a similar manner, nitrate-based potential new production was 99-106 mmol C m-2 d-1. This demonstrates that iron supply limits new production to only 9-83% of the nitrate-based potential., Cited By (since 1996):103, CODEN: LIOCA, , , Downloaded from: aslo.org/lo/toc/vol_42/issue_3/0419.pdf (9 June 2014).
Author: Gordon, Coale, Johnson
Date: 1997-01-01T00:00:00Z

Title: Oxidation kinetics of manganese (II) in sea water at nanomolar concentrations,
Description: Manganese oxidation rates were determined at low (∼20 nM) concentrations in seawater by measuring dissolved manganese (Mn(II)) using flow injection analysis with chemiluminescence detection. Mn(II) was measured in samples that had been filtered (0.2 μm) and kept in the dark under controlled temperature and pH conditions for time periods up to 6 months. Eight 9 L carboys with mean pH values ranging from 8 to 8.7 were held at 25°C, another carboy (pH = 9.32) was kept at 5°C. Oxidation followed the Morgan (1967) homogeneous rate equation (d[Mn(II)]/dt = k1 [O2][OH-]2 [Mn(II)]). The mean rate constant k1 = 1.7 ± 0.7 × 1012 M-3 d-1 (95% CI), determined using hydroxide ion activities determined with pH measurements on the NBS scale, was in agreement with work by Morgan (1967; k1 = 4 × 1012 M-3 d-1) and Davies and Morgan (1989; k1 = 1.1 × 1012 M-3 d-1) in dilute solutions. The rate constant at 5°C was 1.3 ± 0.3 × 1012 M-3 d-1. If free hydroxide concentrations (based on the free proton pH scale) are used, then the rate constant at 25°C was k*1 = 0.34 ± 0.14 × 1012 M-3 d-1. Autocatalytic increases in Mn(II) oxidation rates, as predicted by a heterogeneous reaction mechanism (Morgan, 1967) (d[Mn(II)]/dt = k′2[Mn(II)][MnO2]) were not observed, indicating that the homogeneous reaction dominates Mn(II) oxidation at low nM concentrations in seawater. Bacteria were enumerated by 4′,6-diamidino-2-phenylindole (DAPI) staining during the experiments. No significant correlation between bacterial concentrations and Mn(II) oxidation rates was found. Copyright © 1997 Elsevier Science Ltd., Cited By (since 1996):26, ,
Author: Von Langen, Johnson, Coale, Elrod
Date: 1997-01-01T00:00:00Z

Title: On the formation of the manganese maximum in the oxygen minimum,
Description: A simple model that accounts for the formation of the Mn maximum in the oxygen minimum is presented here. In this model, Mn is proposed to cycle in a constant proportion to carbon, as do nitrogen and phosphorous. Superimposed on the Mn-carbon cycle is the removal of Mn(II) via scavenging onto sinking particles and transport by vertical diffusion. Scavenging is assumed to follow the rate law observed in the laboratory for Mn(II) oxidation. Manganese (II) concentrations were calculated with the model at stations in the Pacific and Atlantic Oceans and compared with measurements of dissolved Mn. All parameters in the model were based on laboratory measurements or field observations. The model reproduced Mn(II) maxima of the correct concentration and at the correct depth. This agreement was observed at a range of oxygen concentrations. The calculations demonstrate that the Mn maximum can form because of a reduction in the pseudo-first order scavenging rate constant (k′) within the oxygen minimum. The value of k′ will decrease in regions of the water column with low oxygen and pH (k′ = k0 [O2] {OH-}2). These regions will accumulate higher dissolved Mn(II) concentrations before the rate of Mn(II) removal, k′ [Mn(II)], equals the input from remineralization of POC and a steady state is reached. An additional source of Mn, such as flux from continental margin sediments or dissolution of Mn oxides, is not necessary to account for formation of the Mn maximum., Cited By (since 1996):51, ,
Author: Johnson, Coale, Berelson, Gordon
Date: 1996-01-01T00:00:00Z

Title: Iron, nutrient and phytoplankton biomass relationships in upwelled waters of the California coastal system,
Description: We report measurements of dissolvable and particulate iron, particulate Al, nutrients and phytoplankton biomass in surface waters during the termination of one upwelling event and the initiation of a second event in August 2000. These events occurred in the area of the Año Nuevo upwelling center off the coast of central California. The first event was observed after ∼8 days of continuous upwelling favorable winds, while the second event was observed through the onset of upwelling favorable winds to wind reversals ∼3 days later. Coincident with the upwelling signatures of low temperature and high salinity were significantly elevated concentrations of nitrate and silicate with average concentrations greater than 15 and 20 μM, respectively, during both upwelling events. Dissolvable Fe concentrations (TD-Fe) were significantly higher in the second event, 6.5 versus 1.2 nM Fe found in the first event. Nitrate was reduced by ∼5 μM day-1 within this second upwelled plume as compared to a drawdown of ∼2 μM day-1 within the first plume. Silicate was reduced in a ratio of 1.2 mol Si:mol NO3 in the high Fe waters of the second plume as compared to a ratio of 2.2 in the lower Fe waters of the first plume. The observed differences in nutrient utilization are consistent with some degree of iron limitation. The area of increased dissolvable Fe in the second upwelling event was coincident with elevated particulate Fe concentrations, indicating the particulate pool as a possible source of the observed increase in TD-Fe. The elevated particulate Fe in surface waters was a result of resuspended sediments in the bottom boundary layer (BBL) of the shallow shelf being transported to the surface during upwelling. Particulate (and dissolvable) iron concentrations were significantly reduced as upwelling continued. This was most probably due to a decoupling of the BBL from upwelled source waters as the upwelling front moved offshore and/or reduced turbulence in the BBL as upwelling continued. The observed reduction in both particulate and dissolvable Fe, as upwelling continued to deliver macronutrients to surface waters, may result in varying levels of Fe limitation., Cited By (since 1996):35, CODEN: CSHRD, ,
Author: Fitzwater, Johnson, Elrod, Ryan, Coletti, Tanner, Gordon, Chavez
Date: 2003-01-01T00:00:00Z

Title: Determination of zinc in seawater using flow injection analysis with fluorometric detection,
Description: A sensitive technique for the shipboard determination of zinc in seawater has been developed. The technique couples flow injection analysis with fluorometric detection (FIA-FL). A cation exchange column was used to separate zinc from interfering alkali and alkaline earth ions and to concentrate Zn from seawater. The organic indicator ligand, p-tosyl-8-aminoquinoline, was used to form a complex with zinc, the fluorescence of which was determined with a flow-through fluorometer. The detection limit (defined as three times the standard deviation of the blank, n = 4) was 0.1 nM for a 4.4-mL sample. The precision based on the replicate analysis of samples containing 4.3 nM Zn was ±6% (n = 5). A single sample can be analyzed in 6 min. The technique was determined to be accurate on the basis of analysis of the standard seawater solutions CASS-2 and N ASS-2 and by comparison with previous reliable investigations. A typical profile of 12 samples along with standards and blanks can be completed in triplicate in 5.5 h., Cited By (since 1996):31, CODEN: ANCHA, ,
Author: Nowicki, Johnson, Coale, Elrod, Lieberman
Date: 1994-01-01T00:00:00Z

Title: Diversity and natural history of a Lithothamnion muelleri-Sargassum horridum community in the Gulf of California
Description: We quantitatively assessed the relative contribution of the rhodolith form of Lithothamnion muelleri, a likely foundation species, to macroorganism diversity in a community also inhabited by the large fucalean Sargassum horridum at a site near Cabo Los Machos at the mouth of Bahía Concepción, Baja California Sur, Mexico. The composition and abundance of seaweeds, epibenthic invertebrates, and fish were estimated in March and October 2003, and invertebrates within rhodoliths (cryptofauna) in March 2003. Rhodoliths and Sargassum horridum had the highest cover of all organisms within the 0.5-km 2, 2-8-m-deep cobble-sand site. A total of 29 species of seaweeds, 40 taxa of benthic invertebrates, and 33 species of fish were sampled in transects and quadrats. Macroalgal and fish diversity were similar between sampling times as a result of loss and replacement of taxa, but benthic invertebrate diversity declined without replacement from March to October. Rhodolith cover was similar at both sampling times. The cover and density of S. horridum were highly seasonal, and the non-rhodolith flora changed from abundant S. horridum (35% cover) in March to abundant red algal turf in October (22% cover). The sea urchin Arbacia incisa, tunicates, and polychaetes were the most abundant epibenthic invertebrates in March, but declined by October, the former to zero. Grunts (Haemulon maculicauda) and porgies (Calamus brachysomus) were the most abundant fish at both sampling times, but there were large temporal changes in some other species, especially schooling fishes. Rhodolith density in March was 24 ind m -2, with numerous individuals >8 cm diameter. Fifteen rhodoliths from a range of size classes contained 114 cryptofaunal taxa with an average of 40 taxa /individual in the largest rhodoliths. These results show the importance of rhodolith habitat to diversity, the large temporal changes in some assemblages, and the exceptionally high diversity of this subtropical community.
Author: Foster, McConnico, Lundsten, Wadsworth, Kimball, Brooks, Medina-López, Riosmena-Rodríguez, Hernández-Carmona, Vásquez-Elizondo, Johnson, Steller
Date: 2007-01-01T00:00:00Z

Title: What controls dissolved iron concentrations in the world ocean?,
Description: Dissolved (<0.4 μm) iron has been measured in 354 samples at 30 stations in the North and South Pacific, Southern Ocean and North Atlantic by the Trace Metals Laboratory at Moss Landing Marine Laboratories. These stations are all more than 50 km from a continental margin. The global distribution of dissolved iron, which is derived from these profiles, is remarkable for several reasons. The dissolved iron profiles have a uniform shape with a nutrient-like profile at each station. Concentrations at the surface are all <0.2 nmol kg-1 and average 0.07 nmol kg-1. Below 500 m, the average concentration is 0.76 nmol kg-1. The largest value in the data set is 1.38 nmol kg-1. There is no inter-ocean fractionation, which is unique for an element with a nutrient-like profile. Published estimates of the iron residence time are on the order of 100 to 200 yr, indicative of rapid removal. Other elements with such short residence times are characterized by vertical profiles that decrease with depth and deep concentrations that decrease with age as water passes from the Atlantic to the Pacific. This is not the case for iron. The largest horizontal changes in dissolved iron are observed in gradients from the continental margin. There is only a factor of three difference between the minimum (0.4 nmol kg-1) and maximum (1.3 nmol kg-1) value in the data set at a depth near 750 m, where variability is at a maximum. The minimum concentrations are found at stations in the remote central Pacific and the maximum values occur at stations adjacent to the continental margin. The major source of iron in the deep sea is generally aeolian deposition. Integrated (surface to 500 m) concentrations of iron at each station are only weakly correlated with the aeolian iron deposition flux, however. This contrasts with other elements such as lead that also have strong atmospheric sources. These observations lead us to conclude that the nutrient-like profile is maintained by a mechanism that reduces the scavenging rate of dissolved iron at concentrations less than 0.6 nmol kg-1. This mechanism may be complexation by strong iron binding ligands, which have been found in both the Atlantic and Pacific at concentrations near 0.6 nM. This apparent solubility would act to diminish inter-ocean fractionation. It would allow a nutrient-like profile to develop before scavenging began to remove iron. In order to test the concept, we developed a numerical model to make quantitative predictions of dissolved iron concentrations from place to place. The dissolved iron source in the ocean interior is remineralization from sinking particulate organic matter. Scavenging removes dissolved iron only at concentrations greater than the apparent solubility. The only geographically variable parameter in the model is the export flux of carbon from the surface layer, which carries iron with it. The model generated dissolved iron profiles, based on measured or estimated values of the carbon export flux, are in remarkable agreement with the observed profiles at all stations from the North Atlantic through the Southern Ocean to the North Pacific., Cited By (since 1996):386, CODEN: MRCHB, Oceanography, , ,
Author: Johnson, Michael Gordon, Coale
Date: 1997-01-01T00:00:00Z

Title: Variable responses of temperate calcified and fleshy macroalgae to elevated pCO2 and warming
Description: Anthropogenic carbon dioxide (CO2) emissions simultaneously increase ocean temperatures and reduce ocean surface pH, a process termed ocean acidification (OA). OA is expected to negatively affect the growth and physiology of many calcified organisms, but the response of non-calcified (fleshy) organisms is less well understood. Rising temperatures and pCO2 can enhance photosynthetic rates (within tolerance limits). Therefore, warming may interact with OA to alter biological responses of macroalgae in complicated ways. Beyond thresholds of physiological tolerance, however, rising temperatures could further exacerbate negative responses to OA. Many studies have investigated the effects of OA or warming independently of each other, but few studies have quantified the interactive effects of OA and warming on marine organisms. We conducted four short-term independent factorial CO2 enrichment and warming experiments on six common species of calcified and fleshy macroalgae from southern California to investigate the independent and interactive effects of CO2 and warming on growth, carbonic anhydrase (CA) enzyme activity, pigment concentrations, and photosynthetic efficiency. There was no effect of elevated pCO2 on CA activity, pigment concentration, and photosynthetic efficiency in the macroalgal species studies.However,we found that calcareous algae suffered reduced growth rates under high pCO2 conditions alone, although the magnitude of the effect varied by species. Fleshy algae had mixed responses of growth rates to high pCO2, indicating that the effects of pCO2 enrichment are inconsistent across species. The combined effects of elevated pCO2 and warming had a significantly negative impact on growth for both fleshy and calcareous algae; calcareous algae experienced five times more weight loss than specimens in ambient control conditions and fleshy growth was reduced by 76%. Our results demonstrate the need to study the interactive effects of multiple stressors associated with global change on marine communities., http://icesjms.oxfordjournals.org/content/early/2015/09/25/icesjms.fsv168.abstract, Advanced view
Author: Kram, Price, Donham, Johnson, Kelly, Hamilton, Smith
Date: 2015-09-25T00:00:00Z

Title: Biogenic matter diagenesis on the sea floor,
Description: Benthic chamber measurements of the reactants and products involved with biogenic matter diagenesis (oxygen, ammonium, nitrate, silicate, phosphate, TCO2, alkalinity) were used to define fluxes of these solutes into and out of the sediments off southern and central California. Onshore to offshore transects indicate many similarities in benthic fluxes between these regions. The pattern of benthic organic carbon oxidation as a function of water depth, combined with published sediment trap records, suggest that the supply of organic carbon from vertical rain can just meet the sedimentary carbon oxidation + burial demand for the central California region between the depths 100-3500 m. However, there is not enough organic carbon raining through the upper water column to support its oxidation and burial in the basins off southern California. Lateral transport and focusing of refractory carbon within these basins is proposed to account for the carbon buried. The organic carbon burial efficiency is greater off southern California (40-60%) compared to central California (2-20%), even though carbon rain rates are comparable. Oxygen uptake rates are not sensitive to bottom water oxygen concentrations nor to the bulk wt. % organic carbon in surficial sediments. Nitrate uptake rates are well defined by the depth of oxygen penetration into the sediments and the overlying water column nitrate concentration. Nitrate uptake accounts for about 50% of the total denitrification taking place in shelf sediments and denitrification (0.1-1.0 mmolN/m2d) occurs throughout the entire study region. The ratio of carbon oxidized to opal dissolved on the sea floor is constant (0.8 ± 0.2) through a wide range of depths, supporting the hypothesis that opal dissolution kinetics may be dominated by a highly reactive phase. Sea floor carbonate dissolution is negligible within the oxygen minimum zone and reaches maximal rates just above and below this zone (0.2-2.0 mmol/m2d)., Cited By (since 1996):72, Oceanography, ,
Author: Berelson, McManus, Coale, Johnson, Kilgore, Burdige, Pilskaln
Date: 1996-01-01T00:00:00Z

Title: An example crossover experiment for testing new vicarious calibration techniques for satellite ocean color radiometry,
Description: Vicarious calibration of ocean color satellites involves the use of accurate surface measurements of waterleaving radiance to update and improve the system calibration of ocean color satellite sensors. An experiment was performed to compare a free-fall technique with the established Marine Optical Buoy (MOBY) measurement. It was found in the laboratory that the radiance and irradiance instruments compared well within their estimated uncertainties for various spectral sources. The spectrally averaged differences between the National Institute of Standards and Technology (NIST) values for the sources and the instruments were<2.5% for the radiance sensors and<1.5% for the irradiance sensors. In the field, the sensors measuring the above-surface downwelling irradiance performed nearly as well as they had in the laboratory, with an average difference of<2%.While the water-leaving radiance L w calculated from each instrument agreed in almost all cases within the combined instrument uncertainties (approximately 7%), there was a relative bias between the two instrument classes/techniques that varied spectrally. The spectrally averaged (400-600 nm) difference between the two instrument classes/techniques was 3.1%. However, the spectral variation resulted in the freefall instruments being 0.2% lower at 450 nm and 5.9% higher at 550 nm. Based on the analysis of one matchup, the bias in L w was similar to that observed for L u(1 m) with both systems, indicating the difference did not come from propagating L u(1 m) to L w. © 2010 American Meteorological Society., Cited By (since 1996):6, Oceanography, CODEN: JAOTE, ,
Author: Voss, Mclean, Lewis, Johnson, Flora, Feinholz, Yarbrough, Trees, Twardowski, Clark
Date: 2010-01-01T00:00:00Z

Title: Biogeochemistry of hydrothermal vent mussel communities,
Description: Cited By (since 1996):64, Invertebrates, CODEN: DRORE, Continuous measurements of sulfide, silicate and temperature were made in situ from the submersible Alvin in the Rose Garden and New Vent hydrothermal fields of the Galapagos Spreading Center. Continuous measurements of temperature also were made for an 18 day period in the Rose Garden field. The results demonstrate several adaptations that appear to have contributed to the success of the vent mussel Bathymodiolus thermophilus in the Rose Garden. Dense clusters of B. thermophilus can disperse the hydrothermal fluids laterally for distances of several meters. This results in a large increase in the area of the redox transition zone, where both dissolved oxygen and hydrogen sulfide are available. As a result, the animal communities can grow to occupy areas that would not otherwise provide adequate reduced substrates. Measurements of the temperature demonstrate a distinct tidal periodicity. This periodicity will result in a large range of environmental conditions within the vent community. The mussel can tolerate these wide ranges in condition because of its ability to accept long periods of anoxia and to filter feed., ,
Author: Johnson, Childress, Beehler, Sakamoto
Date: 1994-01-01T00:00:00Z

Title: Organochlorines and other environmental contaminants in muscle tissues of sportfish collected from San Francisco Bay,
Description: Edible fish species were collected from 13 locations throughout San Francisco Bay, during the spring of 1994, for determination of contaminant levels in muscle tissue. Species collected included white croaker, surfperch, leopard and brown smoothhound sharks, striped bass, white sturgeon and halibut. 66 composite tissue samples were analysed for the presence of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), pesticides, trace elements and dioxin/furans. The US EPA approach to assessing chemical contaminant data for fish tissue consumption was used for identifying the primary chemicals of concern. Six chemicals or chemical groups were found to exceed screening values (SVs) established using the US EPA approach. PCBs (as total Aroclors) exceeded the screening level of 3 ng g -1 in all 66 muscle tissue samples, with the greatest concentrations (638 ng g -1) found near San Francisco's industrial areas. Mercury was elevated (> 0.14 μg g -1) in 40 of 66 samples with the greatest concentrations (1.26 μg g -1) occurring in shark muscle tissues. Concentrations of the organochlorine pesticides dieldrin, total chlordane and total dichlorodiphenyltrichloroethane (DDT) exceeded screening levels in a number of samples. Dioxin/furans (as toxic equivalent concentrations (TEQ's)) were elevated (> 0.15 pg g -1) in 15 of the 19 samples analysed. Fish with high lipid content (croaker and surfperch) in their muscle tissue generally exhibited higher organic contaminant levels while fish with low lipid levels (halibut and shark) exhibited lower organic contaminant levels. Tissue samples taken from North Bay stations most often exhibited high levels of chemical contamination. The California Office of Health Hazard Assessment is currently evaluating the results of this study and has issued an interim Health Advisory concerning the human consumption of fish tissue from San Francisco Bay., Cited By (since 1996):61, CODEN: MPNBA, ,
Author: Fairey, Taberski, Lamerdin, Johnson, Clark, Downing, Newman, Petreas
Date: 1997-01-01T00:00:00Z

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: Aspects of the life histories of grass rockfish, Sebastes rastrelliger, and brown rockfish, S. auriculatus, from southern California,
Description: We collected data on age-length and length-weight relationships, age and length at first maturity, and spawning seasons of grass rockfish, Sebastes rastrelliger, and brown rockfish, S. auriculatus, off southern California. In addition, we also collected data on fecundity of grass rockfish. For both species, males and females grew at the same rates and von Bertalanffy age-length parameters for grass rockfish were l(∞)=51.3 cm, k=0.11, t0=-2.41 and for brown rockfish l(∞)=51.4 cm, k=0.16, t0=-0.55. Male and female grass rockfish matured at about the same length and age, between 22 and 28 cm and between 2 and 5 yr. There was also little difference between the sexes for brown rockfish; they matured between 19 and 32 cm and between 3 and 6 yr. Grass rockfish spawned from January to March, peaking during January; brown rockfish spawned from January to June (and perhaps August), also peaking in January. Fecundity of grass rockfish ranged from about 80,000-760,000 eggs., Cited By (since 1996):10, Fish and Fisheries, CODEN: FSYBA, ,
Author: Love, Johnson
Date: 1999-01-01T00:00:00Z

Title: Geochemistry of barium in marine sediments,
Description: Variations in the accumulation rate of barium in marine sediments are thought to be indicative of variations in marine biological productivity through time. However, the use of Ba as a proxy for paleoproductivity is partly dependent upon its being preserved in the sediment record in a predictable or consistent fashion. Arguments in favor of high Ba preservation are partly based on the assumption that sediment porewaters are generally at saturation with respect to pure barite. The idea is that because nondetrital sedimentary Ba predominantly exists as barite, porewater saturation would promote burial. We present sediment porewater, sediment solid phase, and benthic incubation chamber data suggesting that solid-phase Ba preservation may be compromised in some geochemical settings. We propose that under suboxic diagenetic conditions, characterized by low bottom water oxygen and high organic carbon respiration rates, Ba preservation may be reduced. Independent of the mechanism, if this assertion is true, then it becomes important to know when the Ba record is unreliable. We present evidence demonstrating that the sedimentary accumulation of authigenic U may serve as a proxy for when the Ba record is unreliable. We then provide an example from the Southern Ocean during the last glacial period where high authigenic U concentrations coincide with high Pa:Th ratios and high accumulation rates of biogenic opal, but we find low accumulation rates of sedimentary Ba. Thus, for the study sites presented here during the last glacial, we conclude that Ba is an unreliable productivity proxy., Cited By (since 1996):163, ,
Author: McManus, Berelson, Klinkhammer, Johnson, Coale, Anderson, Kumar, Burdige, Hammond, Brumsack, McCorkle, Rushdi
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: Cadmium flux in Los Angeles/Long Beach harbours and at sites along the California continental margin,
Description: Fluxes of dissolved cadmium were measured in situ using benthic flux chambers at stations in Los Angeles/Long Beach harbour and at sites on the California continental margin. Cadmium fluxes ranged from -0.212 to 0.118 μmol m-2 d-1 indicating that Cd flux may either be into or out of sediments. Correlations between Cd flux and carbon oxidation rate and between carbon oxidation rate and sulfate reduction indicate that anaerobic microbial degradation was the major process controlling both the sign and the magnitude of cadmium fluxes at stations in Los Angeles and Long Beach harbours. A simple box model based on sediment fluxes and water column concentrations indicates cadmium has a residence time of 47 days within the Los Angeles/Long Beach harbour system, similar to the hydraulic residence time. Sedimentary flux is, therefore, sufficient to account for water column cadmium concentration in inner harbour areas, suggesting that the sediments are the dominant source and sink of cadmium in these areas of the harbour. Comparison of the cadmium: phosphate ratio for the Los Angeles/Long Beach harbour water column with those reported for the northeast Pacific suggests that distributions of Cd in the study area were elevated over expected values but appear to be dominated by natural physical and biogeochemical processes. © 2001 Academic Press., Cited By (since 1996):9, Oceanography, CODEN: ECSSD, ,
Author: Colbert, Coale, Berelson, Johnson
Date: 2001-01-01T00:00:00Z

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: Direct ultraviolet spectrophotometric determination of total sulfide and iodide in natural waters,
Description: A technique is described that allows the determination of total dissolved sulfide in natural waters using direct ultraviolet detection of the HS- ion. The concentration of bisulfide is determined by measuring absorption from 214 to 300 nm and then deconvolution of the HS- spectra from the complex spectrum of natural fluids. A nonlinear least-squares fitting approach is used for the deconvolution. At a pH near 8, where >95% of total sulfide is present as HS-, the results are indistinguishable from total sulfide measured using the methylene blue method in a wide range of sample types and matrixes including freshwater from groundwater wells, marine hydrothermal vent fluids, and marine sediment porewaters. The method allows simultaneous determination of other UV-absorbing ions, including nitrate, bromide, and iodide, in samples with low total sulfide concentrations. Bisulfide concentrations can be determined in samples with low background absorption, such as well water and hydrothermal fluids, with a detection limit of <1 μM. The detection limit for bisulfide in sediment porewaters that have a high organic loading, which produces background absorbances of ∼0.5 A at 260 nm in a 1-cm cuvette, is 5 μM. The only chemical manipulation required is buffering acidic samples to pH > 7 and filtration of particulate-rich samples., Cited By (since 1996):36, Oceanography, CODEN: ANCHA, ,
Author: Guenther, Johnson, Coale
Date: 2001-01-01T00:00:00Z

Title: Stray light correction algorithm for multichannel hyperspectral spectrographs,
Description: An algorithm is presented that corrects a multichannel fiber-coupled spectrograph for stray or scattered light within the system. The efficacy of the algorithm is evaluated based on a series of validation measurements of sources with different spectral distributions. This is the first application of a scattered-light correction algorithm to a multichannel hyperspectral spectrograph. The algorithm, based on characterization measurements using a tunable laser system, can be extended to correct for finite point-spread response in imaging systems. © 2012 Optical Society of America., Cited By (since 1996):1, Oceanography, CODEN: APOPA, ,
Author: Feinholz, Flora, Brown, Zong, Lykke, Yarbrough, Johnson, Clark
Date: 2012-01-01T00:00:00Z

Title: Manganese flux from continental margin sediments in a transect through the oxygen minimum,
Description: The flux of manganese from continental margin sediments to the ocean was measured with a free-vehicle, benthic flux chamber in a transect across the continental shelf and upper slope of the California margin. The highest fluxes were observed on the shallow continental shelf. Manganese flux decreased linearly with bottom water oxygen concentration, and the lowest fluxes occurred in the oxygen minimum zone (at a depth of 600 to 1000 meters). Although the flux of manganese from continental shelf sediments can account for the elevated concentrations observed in shallow, coastal waters, the flux from sediments that intersect the oxygen minimum cannot produce the subsurface concentration maximum of dissolved manganese that is observed in the Pacific Ocean., Cited By (since 1996):47, Oceanography, CODEN: SCIEA, ,
Author: Johnson, Berelson, Coale, Coley, Elrod, Fairey, Iams, Kilgore, Nowicki
Date: 1992-01-01T00:00:00Z

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

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