Search results

Title: A Late Pleistocene time-series of bottom-current speed in the Vema Channel,
Description: A coarsening of the mean particle size of the carbonate-free silt fraction from sea-floor samples below 4000 m in the Vema Channel has been used to separate high-velocity Antarctic Bottom Water (AABW) from the overlying, slower North Atlantic Deep Water (NADW). A time-series of fluctuations in bottom-current speed within the modern AABW/NADW transition zone was examined by determining the particle-size distribution of sediments from eight gravity cores with a high-resolution stratigraphy for the past 250 kyrs. The bottom-current paleospeed was inferred from a correlation of particle size in seafloor samples with mean current speed from nearby current-meters. The mean bottom-current speed at depths comparable to modern AABW was highest (7-10 cm/s) during interglacial to glacial transitions corresponding to the oxygen isotopic stage 6/7 and 4/5 boundaries and at present. The mean bottom-current speed at depths comparable to modern NADW was nearly uniform for most of the past 250 kyrs except during glacial oxygen isotopic stage 2 when the speed dropped to 2 cm/s, or one-half of the present speed. The application of the "calibrated" particle-size method to examine bottom-current paleospeed allows testing of paleoceanographic models which rely on assumptions or inferences of changes in bottom-water production rate during the late Pleistocene paleoclimatic fluctuations. © 1986., Cited By (since 1996):17, CODEN: PPPYA, , , Oceanography
Author: Ledbetter
Date: 1986-01-01T00:00:00Z

Title: Continental-shelf sediment as a primary source of iron for coastal phytoplankton,
Description: The availability of iron, an essential nutrient, controls rates of phytoplankton primary productivity in the open-ocean, upwelling ecosystems of the equatorial Pacific. Upwelling injects large amounts of macronutrients into the euphotic zone of eastern boundary currents, such as the California Current System (CCS), where iron can become the limiting factor on productivity. Iron addition to samples from some areas of the CCS has been shown to increase rates of biomass production, but the processes that control iron availability in these systems remain poorly understood. Here we report measurements of dissolvable iron (that is, dissolved plus leachable iron at pH 3) in transects across the CCS in March of 1997 and 1998. We found high concentrations of iron in 1997 during strong upwelling conditions. During the 1998 El Nino, the concentration of dissolvable iron in surface waters was low, even though that year was marked by high river flow and low offshore salinity. These results indicate that the primary source of iron in the CCS is resuspension of particles in the benthic boundary layer, followed by upwelling of this iron-rich water, rather than direct riverine input. This source of iron must be an essential but variable component of the high productivity found in upwelling ecosystems., Cited By (since 1996):172 Oceanography, CODEN: NATUA, ,
Author: Johnson, Chavez, Friederich
Date: 1999-01-01T00:00:00Z

Title: Estimating rates of acceleration based on the 157-year record of sea level from San Francisco, California, U.S.A.
Description: Breaker, L.C. and Ruzmaikin, A., 2013. Estimating rates of acceleration based on the 157-year record of sea level from San Francisco, California, U.S.A. The question of the acceleration of global sea level rise has gained increasing attention because the present rate of sea level rise is relatively small in comparison to the rates that are predicted to occur in the near future. Recent measurements have come under scrutiny on how to correctly analyze and interpret regional estimates of acceleration. In this context, we employ the Ensemble Empirical Mode Decomposition (EEMD), a data-adaptive method developed for the analysis of nonstationary and nonlinear data to estimate acceleration over the 157-year record of sea level from San Francisco, California. We define sea level acceleration (SLA) as the mean of the second differences of the residual from an EEMD. Using the residual provides a means by which to reduce or eliminate the contaminating influence of decadal and longer-period oscillations in sea level that are folded into estimates obtained using the conventional approach. For the entire record, a value of +0.011 ± 0.003 mm/y2 was obtained for the acceleration and its uncertainty, compared with +0.013 mm/y2, using the conventional approach. The effect of record length is examined by estimating the accelerations for truncated versions of the record, one starting in 1900 and a second in 1925. The accelerations differed in each case from the conventional values, as expected, because the methods are based on different definitions of SLA. © Coastal Education & Research Foundation 2013., Cited By (since 1996):1, Oceanography, CODEN: JCRSE
Author: Breaker, Ruzmaikin
Date: 2013-01-01T00:00:00Z

Title: Sediment flushing observations, earthquake slumping, and benthic community changes in Monterey Canyon head,
Description: A large area of axis sediment (>500 m2) may be annually removed from the head of Monterey Submarine Canyon with the first onshore storm of the fall/winter storm season. In this scenario, flushing events are followed by accumulation of sediment and organic debris-especially macro algae-in the shallow axis. Net accumulation of this fill material increases during the calmer spring and summer until the next fall-flushing. The benthic community at a canyon axis station was characterized by highly fluctuating populations of opportunistic polychaete worm; and gammarid amphipods, primarily Capitella spp., Armandia brevis, and Orchomene pacifica. The canyon axis community was very different from communities living at two other stations where sudden flushing does not occur-an adjacent sloping-wall station and a sandflat station. Sloping-wall and sandflat stations harbored more and longer-lived species, larger individuals, and a less variable population structure during a year of sampling. The Loma Pricta earthquake in the fall of 1989 triggered small sediment slumps on the canyon walls, but it did not trigger axis-flushing. The usual seasonal flushing of the axis occurred 2 weeks after the earthquake with the arrival of the first storm. Benthic communities were reduced in abundance inside earthquake-induced slumps; however, the slumped areas were rapidly colonized by Prionospio pygmaea, a polychaete opportunist common to the sandflat. Surprisingly, the physical and biological impacts of the earthquake ware much less severe than the seasonal axis flushing associated with storms. Observations of sediment-flushing combined with measurements of benthic community changes in Monterey Canyon head represent a step towards an ecological model of mass wasting with implications for the continental shelf and slope and possibly the deep sea., Cited By (since 1996):33, Oceanography, CODEN: CSHRD, ,
Author: Okey
Date: 1997-01-01T00:00:00Z

Title: Cadmium in plankton: Elevated concentrations of Baja California,
Description: 135 Plankton samples were collected in the northwest Pacific Ocean and analyzed for their cadmium content. Concentrations were generally low (2 to 5 micrograms of cadmium per gram, dry wt) in all samples, except for the plankton collected off Baja California, where high values (10 to 20 parts per million) were consistently found on 2 cruises., Cited By (since 1996):24, Oceanography, CODEN: SCIEA, ,
Author: Martin, Broenkow
Date: 1975-01-01T00:00:00Z

Title: Effects of the 1997-1999 El Niño and La Niña events on zooplankton abundance and euphausiid community composition within the Monterey Bay coastal upwelling system,
Description: Zooplankton abundance and euphausiid community composition were sampled seasonally (spring, summer, fall) within Monterey Bay, California, between 1997 and 1999. Measurements of sea surface temperature (SST), mixed layer depth, and upwelling indices provided concurrent data on physical oceanographic parameters. Both total zooplankton and krill abundance dramatically declined in the summer of 1997 coincident with a rapid increase in SST and mixed layer depth. Changes in euphausiid community composition occurred in concert with the decline in overall abundance. The relative abundance of the southern neritic Nyctiphanes simplex increased from August to November in 1997, the abundance of cold temperate Euphausia pacifica decreased significantly, and that of the northern neritic Thysanoessa spinifera declined dramatically. The sudden appearance of an adult cohort of N. simplex in July 1997 suggests that rapid poleward flow characteristic of coastally trapped Kelvin waves occurred between June and July of 1997. The persistent presence of warm temperate and subtropical taxa in samples collected between August 1997 and October 1998 indicates that this poleward flow continued in 1998. Zooplankton abundance, euphausiid community composition, and physical oceanographic parameters gradually returned to a more typical upwelling-dominated state in the spring and summer of 1998. E. pacifica and T. spinifera abundances gradually increased during the summer and fall of 1998, while N. simplex abundance abruptly declined in the spring of 1998. However, this recovery was confined to a narrow coastal band as a result of the onshore movement of the oceanic waters of the California Current. This was reflected by higher than normal numbers of the oceanic Nematoscelis difficilis within samples collected during the spring and summer of 1998. By the spring and summer of 1999, both zooplankton and euphausiid abundance had increased to the highest levels recorded during the 3-year study. Both E. pacifica and T. spinifera abundance increased relative to 1998 while N. simplex was completely absent in all samples. These changes reflected the cooler, highly productive environmental conditions associated with the 1998/1999 La Niña. © 2002 Elsevier Science Ltd. All rights reserved., Cited By (since 1996):43, Oceanography, CODEN: POCNA, ,
Author: Marinovic, Croll, Gong, Benson, Chavez
Date: 2002-01-01T00:00:00Z

Title: Structural control of fluid flow: Offshore fluid seepage in the Santa Barbara Basin, California,
Description: Evidence of active and dormant fluid seepage in the Santa Barbara Basin is observed as active venting of gas and oil, bacterial mats, precipitates of authigenic carbonate, and mud and tar volcanoes. Fluid seepage occurs preferentially in the proximity to faults and faulted anticlines, and to slump scarps. Seepage next to faults and anticlines indicates that hydrocarbon migration and pore fluid expulsion is controlled structurally, with faults acting as preferred conduits for fluid flow across units of low matrix permeability. (C) 2000 Elsevier Science B.V. All rights reserved., Cited By (since 1996):38, Oceanography, CODEN: JGCEA, ,
Author: Eichhubl, Greene, Naehr, Maher
Date: 2000-01-01T00:00:00Z

Title: Stable isotopic ratios of lead in surface waters of the central Pacific,
Description: The geographic variation in the isotopic composition of lead in surface waters of the central Pacific provides new evidence of the global anthropogenic perturbation of the element's cycle. Ratios of 206Pb/207Pb decrease from 1.196 in the northern hemisphere (19°N, 158°W) to 1.176 in the southern hemisphere (15°S, 150°). This decrease parallels the geographic variation in surface concentrations of soluble lead which decrease from 13 ng kg-1 at the northern station to 4 ng kg-1 at the southern station. Both the 206Pb/207Pb and the 206Pb/208Pb ratios of those waters fit between the isotopic ratios of Australian (Broken Hill) and North American (Mississippi Valley) leads which are the predominant sources of leads in anthropogenic emissions to the Pacific Ocean basin., Cited By (since 1996):9, Oceanography, CODEN: MRCHB, ,
Author: Flegal, Schaule, Patterson
Date: 1984-01-01T00:00:00Z

Title: What's happening in Monterey Bay on seasonal to interdecadal time scales,
Description: Daily observations of sea-surface temperature (SST) have been acquired at the southern end of Monterey Bay in Pacific Grove, California since 1919. It is one of the longest oceanographic records off the west coast of North America. The record is examined to determine the major sources of variability in Monterey Bay and beyond, on time scales from seasonal to interdecadal. On seasonal time scales, the spring transition to coastal upwelling, often a major event along the coast of central California, is not well-expressed inside the bay but is detectable, occurring, on average, between mid-March and mid-April. The onset of the Davidson Current in Monterey Bay is well-defined, occurring, on average, in mid-October, ±2-3 weeks. Intraseasonal changes also occur during the spring and summer that may correspond to intrusions of warmer offshore waters into Monterey Bay. Intraseasonal oscillations with periods in the range of 40-50 days occur in Monterey Bay, but compared to their signature along the open coast, their event-like behavior is modified. The annual cycle of surface temperature in Monterey Bay is asymmetric with seasonal warming occurring during the spring and summer, and cooling during the fall. This asymmetry is primarily due to the net surface heat exchange which is positive for most of the year, and, to a lesser extent, the influence cold upwelled waters that are advected into the bay during the spring and summer, observations supported by a simple model that combines both the net surface heat exchange and thermal advection. On interannual time scales, the influence of El Niño warming events is strong. A comparison with the Northern Oscillation Index (NOI) using Singular Spectrum Analysis (SSA), shows that the El Niño signal is often as strong in SST at Pacific Grove as it is in the NOI. On interdecadal time scales, the influence of the Pacific Decadal Oscillation (PDO) is also relatively strong in Monterey Bay, again based on SSA. The integrated anomaly was calculated from the record and reveals regime shifts in Monterey Bay that occurred in 1929, an event that was apparently regional in scale, reflecting a transition from unusually cold to warmer conditions, and the regime change in the PDO that occurred in 1976. Each regime change can be approximated by a step-wise increase in temperature. Finally, linear trends were estimated for the entire record (∼+0.01°C/year), and for the 72-year period from 1930 to 2001 (+0.0042°C/year), i.e., following the regional regime change in 1929. The estimated trend for the last 72 years is not statistically significant; however, it is in close agreement with the long-term trend for the Intergovernmental Panel on Climate Change (IPCC) record of global surface temperature that spans almost 140 years (∼+0.005°C/year). Although the long-term increase in SST at Pacific Grove appears to be consistent with global warming, the integrated anomaly suggests that temperature increases in Monterey Bay have occurred rather abruptly and thus it becomes more difficult to invoke the global warming scenario. Finally, based on the monthly averaged data, the annual cycle, El Niño warming episodes, the PDO, the long-term trend, and the semiannual cycle account for approximately 44%, 18%, 6%, 4%, and 3% of the total variance, respectively, in SST at Pacific Grove. © 2005 Elsevier Ltd. All rights reserved., Cited By (since 1996):11, Oceanography, CODEN: CSHRD, ,
Author: Breaker
Date: 2005-01-01T00:00:00Z

Title: Selenium in San Francisco Bay zooplankton: Potential effects of hydrodynamics and food web interactions,
Description: The potential toxicity of elevated selenium (Se) concentrations in aquatic ecosystems has stimulated efforts to measure Se concentrations in benthos, nekton, and waterfowl in San Francisco Bay (SF Bay). In September 1998, we initiated a 14 mo field study to determine the concentration of Se in SF Bay zooplankton, which play a major role in the Bay food web, but which have not previously been studied with respect to Se. Monthly vertical plankton tows were collected at several stations throughout SF Bay, and zooplankton were separated into two operationally defined size classes for Se analyses: 73-2,000 μm, and ≥2,000 μm. Selenium values ranged 1.02-6.07 μg Se g-1 dry weight. No spatial differences in zooplankton Se concentrations were found. However, there were inter- and intra-annual differences. Zooplankton Se concentrations were enriched in the North Bay in Fall 1999 when compared to other seasons and locations within and outside SF Bay. The abundance and biovolume of the zooplankton community varied spatially between stations, but not seasonally within each station. Smaller herbivorous-omnivorous zooplankton had higher Se concentrations than larger omnivorous-carnivorous zooplankton. Selenium concentrations in zooplankton were negatively correlated with the proportion of total copepod biovolume comprising the large carnivorous copepod Tortanus dextrilobatus, but positively correlated with the proportion of copepod biovolume comprising smaller copepods of the family Oithonidae, suggesting an important role of trophic level and size in regulating zooplankton Se concentrations., Cited By (since 1996):12, Oceanography, CODEN: ESTUD, ,
Author: Purkerson, Doblin, Bollens, Luoma, Cutter
Date: 2003-01-01T00:00:00Z

Title: The effect of elevated levels of phaeophytin in natural water on variable fluorescence measured from phytoplankton,
Description: Variable fluorescence methods are becoming popular in studies related to aquatic photosynthesis. In natural ocean water, phytoplankton co-exist with their zooplankton and flagellate predators, viral parasites and the waste products of digested phytoplankton cells that contain phaeophytin (a chromophore produced by digestion of chlorophyll a). Fast repetition rate fluorometry, a technique mainly applied in phytoplankton studies, was used to evaluate and quantify the effect of phaeophytin abundance in sea water on variable fluorescence parameters: the photochemical quantum yield, Φ F (also known as F v/F m), and the functional cross-section of photosystem 2 (PS2), σ PS2. If the value of Φ F determined is lower than what it actually is, phytoplankton may be labeled as less healthy (or productive) than their true condition. Results were compared with data collected using another widely used variable fluorescence technique: pulse amplitude modulation (PAM). Our study concludes that for significantly elevated levels of phaeophytin in the water, the measured values of Φ F should be corrected to avoid misinterpretation. This conclusion is independent of the measuring instrument. In waters with phaeophytin levels that constitute less than ∼30% of the total measured pigment, no correction is required (<5% change in Φ F is expected). However, as phaeophytin levels rise the effect on Φ F increases and becomes more significant (e.g. Φ F appears 25% lower when the phaeophytin to total pigment ratio is ∼70%). High concentrations of phaeophytin are not often reported in the open ocean. However, in highly productive coastal waters, high levels of phaeophytin can be encountered. The functional cross-section (σ PS2) measurements are not affected by the presence of phaeophytin in the water., Cited By (since 1996):18, CODEN: JPLRD, , , Oceanography
Author: Fuchs, Zimmerman, Jaffe
Date: 2002-01-01T00:00:00Z

Title: Echo character of off-platform carbonates,
Description: A comprehensive study of the nature and distribution of echo types recorded on short-ping (2-5 msec), high-frequency (3.5 kHz) echograms combined with analyses of 100 bottom samples from the off-platform carbonate environment of Northwest Providence Channel (NWPC), Bahamas, has defined qualitative relationships between echo types, sedimentary processes and sediment types. Seven distinct echo types have been observed and their areal distributions mapped. These seven types fall into three larger groups: (I) Distinct; (II) Indistinct; and (III) Hyperbolic. A strong correlation of echo character with sediment type exists for the one distinct (IB) and two indistinct (IIA and IIB) echo types observed. Muddy, pelagic sediments occur in regions characterized by distinct, sharp, continuous, parallel, sub-bottom reflectors (Type IB). Pelagic sediments interbedded with coarse-sediment gravity-flow deposits or slope breccia are characterized by indistinct, discontinuous, intermittent sub-bottom reflectors (Type IIA). Coarse current-winnowed sands or thick biolithoclastic turbidites found near the surface correlate with regions characterized by an indistinct, prolonged echo with no sub-bottom reflectors (Type IIB). Hyperbolic echoes were observed from both erosional and constructional features. The most common echo type (IIIA) in NWPC consists of large, irregular, overlapping hyperbolae with varying vertex elevations above the sea floor which originate from areas of large-scale submarine erosional topography. This echo type is much more common on the slope south of Little Bahama Bank than north of Great Bahama Bank, indicating different sedimentary processes operative along these two deep carbonate bank margins. In contrast, echoes consisting of discrete single hyperbolae with approximately equal vertex elevations above the sea floor (Type IIIG) correlate with in-situ constructional deep-water bioherms (lithoherms). This study demonstrates the usefulness of 3.5-kHz profiles in mapping near-surface off-platform carbonate sediments. The relationships between echo types and sedimentary processes and/or sediment types described here in a region with good bottom-sample control may serve as a model to facilitate rapid mapping of off-platform carbonates in areas where there is less control. © 1979., Cited By (since 1996):6, Oceanography, CODEN: MAGEA, ,
Author: Mullins, Boardman, Neumann
Date: 1979-01-01T00:00:00Z

Title: Dissolved organic carbon in the Atlantic, Southern and Pacific oceans,
Description: The amount of dissolved organic carbon (DOC) in sea water is controversial 1,2. Using a high-temperature catalytic oxidation (HTCO) technique, Sugimura and Suzuki 3 reported that surface waters contained 2-4 times as much DOC as that measured previously using wet chemistry and ultraviolet oxidation techniques 4,5. They also observed a relationship between DOC content and apparent oxygen utilization suggesting that the consumption of DOC is responsible for oxygen depletion in the deep sea. How to reconcile the apparent differences between these techniques has not been clear. Here we provide independent confirmation of the findings of Sugimura and Suzuki. We collected surface and deep waters from the equatorial Pacific Ocean, the Drake passage and the Atlantic Ocean south of Iceland, and analysed their DOC content using the HTCO methodology 3. We found DOC concentrations 2-3 times higher than those measured previously. These results imply that the carbon content of the oceans has previously been underestimated by 10 12 (1,000 billion) tonnes, and that the new estimated total of 1,800 billion tonnes represents one of the largest carbon reservoirs on Earth 6. We found no evidence of a cause-and-effect relationship between DOC and apparent oxygen utilization., Cited By (since 1996):35, Oceanography, CODEN: NATUA, ,
Author: Martin, Fitzwater
Date: 1992-01-01T00:00:00Z

Title: Boundary-interior exchange: Reviewing the idea that internal-wave mixing enhances lateral dispersal near continental margins,
Description: Near-boundary mixing affects the dispersal of seawater constituents and may have important consequences for ecological and geological processes since continental boundaries are a fundamental source of lithogenic sediments, nutrients, iron and carbon. This paper examines the idea that gravitational collapse after near-boundary vertical mixing events leads to enhanced dispersal in the horizontal (along-isopycnal) direction. Dye studies from the continental shelf and laboratory investigations of intrusions generated by internal-wave breaking suggest that this is a viable mechanism for offshore dispersal of boundary-layer fluid. However, there have been few attempts to examine this process in the ocean or to quantify it in a form amenable to parameterization. Here this process is considered primarily for continental slopes and conditions of relatively uniform stratification, rather than for shelves where the boundary can intersect a front or seasonal thermocline. This paper reviews a selection of studies examining this concept in the laboratory and ocean, and reviews studies linking internal-wave reflection and mixing to the offshore dispersal of suspended sediment from continental margins. © 2006 Elsevier Ltd. All rights reserved., Cited By (since 1996):27, Oceanography, CODEN: DSROE, ,
Author: McPhee-Shaw
Date: 2006-01-01T00:00:00Z

Title: Thallium concentrations in seawater,
Description: Measurements of the concentration of thallium in seawater collected from numerous ocean locations ranged from 12 to 16 ng kg-1. Variations between the Atlantic and Pacific Oceans, between the northern and southern hemispheres of the Pacific Ocean, and between surface and deep waters of both the Pacific and Atlantic oceans were comparable with the precision of the analyses. This relatively constant distribution indicates that the element's cycle in seawater may be similar to those of the alkali metals which are its principal biogeochemical analogues. © 1985., Cited By (since 1996):34, Oceanography, CODEN: MRCHB, ,
Author: Flegal, Patterson
Date: 1985-01-01T00:00:00Z

Title: Diurnal-period internal waves near Point Conception, California,
Description: Diurnal-period internal waves were observed near Point Conception California, using an array of moorings extending 120 km along the inner shelf. The waves have an along-shelf coherence scale of at least 50 km, and appear to propagate nearly straight onshore. Wave amplitudes vary over time, depending on thermal stratification and the amplitude of the diurnal sea breeze oscillation. Barotropic tides and vorticity over the mid-shelf are not correlated with internal wave amplitude. Large amplitude internal waves, with supercritical Froude numbers, are observed in mid-summer. Although such waves may drive vertical mixing and cross-shelf transport of passive particles, there is no significant correlation between wave amplitude and invertebrate settlement in the Santa Barbara Channel. © 2009 Elsevier Ltd. All rights reserved., Cited By (since 1996):7, Oceanography, CODEN: ECSSD, ,
Author: Cudaback, McPhee-Shaw
Date: 2009-01-01T00:00:00Z

Title: A numerical study on the role of wind forcing, bottom topography, and nonhydrostacy in coastal upwelling
Description: The responses of coastal upwelling to different magnitudes of wind stress over a narrow and a wide shelf are studied using a 3-D primitive equation numerical model. The results show that the position of the upwelling front depends on both the strength and the duration of the wind forcing. The comparison between different shelf widths shows that wide shelf will limit the cold water intrusion, so that the corresponding decrease in sea surface temperature is less compared to narrow shelves. Besides, the difference between hydrostatic and nonhydrostatic model results shows that nonhydrostatic effects will enhance the growth of surface meandering, and can be more pronounced near steep fronts. Although difference does exist, our results show that the nonhydrostatic effects are very small at least in this idealized study case. © 2011 Elsevier Ltd., Cited By (since 1996):1, CODEN: ECSSD, Oceanography
Author: Jiang, Yan, Tseng, Breaker
Date: 2011-01-01T00:00:00Z

Title: Temperature dependence of nitrate reductase activity in marine phytoplankton: Biochemical analysis and ecological implications,
Description: The temperature dependence of NADH:NR activity was examined in several marine phytoplankton species and vascular plants. These species inhabit divergent thermal environments, including the chromophytes Skeletonema costatum (12-15°C), Skeletonema tropicum (18-25°C), Thalassiosira antarctica (-2 to 4°C), and Phaeocystis antarctica (-2 to 4°C), the green alga Dunaliella tertiolecta (14-28°C), and the vascular plants Cucurbita maxima (20-35°C) and Zea mays (20-25°C). Despite the difference in growth habitats, similar temperature response curves were observed among the chromophytic phytoplankton, with temperatures optimal for NR activity being between 10-20°C. In contrast, the chlorophyll b-containing alga and vascular plants exhibited optimal temperatures for NR activity above 30°C. Such dramatic differences in NR thermal characteristics from the two taxonomic groups reflect a divergence in NR structure that may be associated with the evolutionary diversification of chromophytes and chlorophytes. Further, it suggests a potential contribution of the thermal performance of NR to the geographic distributions, seasonal abundance patterns, and species composition of phytoplankton communities. NR partial activities, which assess the individual functions of Mo-pterin and FAD domains, were evaluated on NR purified from S. costatum to determine the possible causes for high temperature (>20°C) inactivation of NR from chromophytes. It was found that the FAD domain and electron transport among redox centers were sensitive to elevated temperatures. S. costatum cells grown at 5, 15, and 25°C exhibited an identical optimal temperature (15°C) for NADH:NR activity, whereas the maximal NR activity and NR protein levels differed and were positively correlated with growth temperature and growth rate. These findings demonstrate that thermal acclimation of NO 3 - reduction capacity is largely at the level of NR protein expression. The consequences of these features on NO 3 - utilization are discussed., Cited By (since 1996):26, Seaweeds, Oceanography, CODEN: JPYLA, ,
Author: Gao, Smith, Alberte
Date: 2000-01-01T00:00:00Z

Title: ENSO and variability of the Antarctic peninsula pelagic marine ecosystem,
Description: The West Antarctic Peninsula region is an important source of Antarctic krill (Euphausia superba) in the Southern Ocean. From 19802004 abundance and concentration of phytoplankton and zooplankton, krill reproductive and recruitment success and seasonal sea ice extent here were significantly correlated with the atmospheric Southern Oscillation Index and exhibited three- to five-year frequencies characteristic of El NioSouthern Oscillation (ENSO) variability. This linkage was associated with movements of the Southern Antarctic Circumpolar Current Front and Boundary, a changing influence of Antarctic Circumpolar Current and Weddell Sea waters, and eastward versus westward flow and mixing processes that are consistent with forcing by the Antarctic Dipole high-latitude climate mode. Identification of hydrographic processes underlying ecosystem variability presented here were derived primarily from multi-disciplinary data collected during 19902004, a period with relatively stable year-to-year sea ice conditions. These results differ from the overwhelming importance of seasonal sea ice development previously established using 19801996 data, a period marked by a major decrease in sea ice from the Antarctic Peninsula region in the late 1980s. These newer results reveal the more subtle consequences of ENSO variability on biological responses. They highlight the necessity of internally consistent long-term multidisciplinary datasets for understanding ecosystem variability and ultimately for establishing well-founded ecosystem management. Furthermore, natural environmental variability associated with interannual- and decadal-scale changes in ENSO forcing must be considered when assessing impacts of climate warming in the Antarctic PeninsulaWeddell Sea region. © Antarctic Science Ltd 2009., Cited By (since 1996):20, Antarctica, Invertebrates, Oceanography, CODEN: ANTSE, ,
Author: Loeb, Hofmann, Klinck, Holm-Hansen, White
Date: 2009-01-01T00:00:00Z

Title: A model for estimating cross-shore surface transport with application to the New Jersey Shelf,
Description: A one-dimensional, steady state numerical model is developed for estimating cross-shore surface transport in shallow waters, where the water depth is comparable to boundary layer thickness. The model is used to solve a momentum equation which describes the cross-shore balance. To validate the model, acoustic Doppler current profiler (ADCP) current data collected during an experiment off the New Jersey shelf in the summer of 1996 are used to estimate the cross-shore surface transport during that period and then compared with model predictions based on the local wind. The success of the model in estimating the cross-shore surface transport leads to an improved version of the conventional upwelling index (i.e., the Bakun Index), particularly for coastal areas with wide and shallow shelves, such as the east coast of the United States. Finally, the model, because of its simplicity, is well suited for operational applications where computational resources may be limited. Copyright 2010 by the American Geophysical Union., Cited By (since 1996):2, Art. No.: C04017, , , Oceanography
Author: Jiang, Breaker, Yan
Date: 2010-01-01T00:00:00Z

Title: Seawater recharge into oceanic crust: IODP Exp 327 Site U1363 Grizzly Bare outcrop,
Description: Systematic differences in sediment thermal and pore water chemical profiles from Integrated Ocean Drilling Program Site U1363 document mixing and reaction within the basaltic crust adjacent to Grizzly Bare outcrop, a site of hydrothermal recharge into 3.6 My-old basaltic crust. A transect of seven holes was drilled ∼50 m to ∼750 m away from the base of the outcrop. Temperatures at the sediment-basement interface increase from ∼6°C to >30°C with increasing distance from the outcrop, and heat flow is suppressed within several hundred meters from the outcrop. Calculated fluid compositions at the sediment-basement interface are generally explained by mixing between bottom seawater and altered crustal basement fluids, with a composition similar but not identical to fluids from seeps at Baby Bare outcrop, located ∼45 km to the northeast. Reactions within upper basement and overlying sediment affect a variety of ions (Mn, Fe, Mo, Si, PO4 3-, V, and U) and δ13DIC, indicating a diagenetic influence and diffusive exchange with overlying sediment pore waters. The apparent 14C age of basal pore fluids is much older than bottom seawater. Collectively, these results are consistent with seawater recharge at Grizzly Bare outcrop; however, there are strong gradients in fluid composition within 50 m of the outcrop, providing evidence for complex flow paths and vigorous mixing of young, recently recharged seawater with much older, more reacted basement fluid. The proximity of these altered fluids to the edge of the outcrop raises the possibility for fluid seepage from the outcrop in addition to seawater recharge. ©2013. American Geophysical Union. All Rights Reserved., Oceanography, , , Downloaded from: http://onlinelibrary.wiley.com/doi/10.1002/ggge.20131/pdf (16 June 2014).
Author: Wheat, Hulme, Fisher, Orcutt, Becker
Date: 2013-01-01T00:00:00Z

Title: Spatial and temporal patterns of zooplankton biomass in Monterey Bay, California, during the 1991-1993 El Niño, and an assessment of the sampling design,
Description: To estimate spatial and temporal zooplankton biomass, and the appropriateness of the sampling design, eighteen surveys were conducted in Monterey Bay, California, between November 1991 and August 1993. Vertical tows were taken to estimate zooplankton biomass in six regions of the bay on each survey day. In year 1. when 100-m vertical tows were made, zooplankton biomass peaked in January, March, and August; in year 2. when 50-m vertical tows were made, biomass peaked in April, August, and October. Mean zooplankton biomass differed significantly among seasons for both years, but trends differed between years. In year 1, mean biomass measured in the Davidson and oceanic seasons was significantly greater than in the upwelling season. In year 2, mean biomass measured in the upwelling and oceanic seasons was significantly greater than in the Davidson period. The seasonal trends in zooplankton biomass during this study were representative of similar trends for the phytoplankton cycle in Monterey Bay, which had a spring and an autumn bloom and decreased biomass in winter. Low zooplankton levels recorded in Monterey Bay during February and April 1992 and January and March 1993 were probably related to an El Niño-Southern Oscillation warm-water event (ENSO) in 1991-93. The sampling regime adequately revealed large-scale spatial (tens of km) and temporal (seasonal) differences in zooplankton biomass, but probably does not adequately describe smaller spatial and shorter temporal processes., Cited By (since 1996):8, Oceanography, , , Downloaded from: http://calcofi.org/publications/ccreports.html (16 June 2014).
Author: Baduini
Date: 1997-01-01T00:00:00Z

Title: The case for iron,
Description: Excess major nutrients occur in offshore areas ranging from the tropical equatorial Pacific to the polar Antarctic. In spite of the great ecological differences in these environments, they share a common trait: iron deficiency. All of these areas are far from Fe-rich terrestrial sources and atmospheric dust loads in these regions are amongst the lowest in the world. Experiments were performed in three nutrient-rich areas: The Gulf of Alaska, the Ross Sea, and the equatorial Pacific. In general, populations without added Fe doubled at rates 11-40% of the expected maxima at various temperatures. The addition of nanomole quantities of Fe increased these doubling rates by factors of 2-3. In spite of the lack of Fe, tightly coupled phytoplankton/zooplankton communities seem to inhabit these major nutrient-rich areas. -from Authors, Cited By (since 1996):341, Oceanography, , , Downloaded from: aslo.org/lo/toc/vol_36/issue_8/1793.pdf (16 June 2014).
Author: Martin, Gordon, Fitzwater
Date: 1991-01-01T00:00:00Z

Title: System of quasi-zonal jets off California revealed from satellite altimetry,
Description: A discrete wavelet transform was applied to satellite altimetry data for the period 1992-2007 off California to decompose the SSH signal into inter-annual, annual, semiannual and shorter period components. For the lowest frequency (inter-annual) component, a system of alternating quasi-zonal jets was detected. The jet system was delineated by a north-south series of quasi-zonal bands of co-rotating eddies; that is, the eddies were embedded in a shearing zonal flow. The direction of eddy rotation alternated between adjacent bands. The temporal behavior of the jet system showed the existence of quasi-stationary states and transitions between them. Observed non-linear effects of the evolution of the jets included southward drift at about 0.2 cm sec -1, deviations of the jets from the zonal direction, and re-forming of the jet system through decay and merging of eddy chains. Copyright 2009 by the American Geophysical Union., Cited By (since 1996):6, Oceanography, Art. No.: L03609, CODEN: GPRLA, , , Downloaded from:http://onlinelibrary.wiley.com/doi/10.1029/2008GL036327/pdf (16 June 2014).
Author: Ivanov, Collins, Margolina
Date: 2009-01-01T00:00:00Z

Title: Taxon-specific analysis of microzooplankton grazing rates and phytoplankton growth rates,
Description: Cited By (since 1996):34, Oceanography, CODEN: LIOCA, We performed laboratory experiments to test the accuracy of using HPLC to estimate taxon-specific grazing and growth rates obtained by the dilution technique. In seven of nine experiments, this technique underesti- mated microzooplankton grazing rates. The average estimated grazing rates were 52% of the true grazing rates for chlorophyll a and 33% for taxon-specific pigments. With the food sources Phaeodactylum tricornutum, Isochrysis galbana, Gymnodinium sp., and Emiliania huxleyi, the clearance rates for Oxyrrhis marina were between 2 x 10-3 and 7 x 10-3 ml grazer- 1 d- 1, at initial food concentrations of ~ 5 x 103 cells ml- 1. At higher food concentrations (1 x 105 cells ml-1) clearance rates decreased to 1 X 10-4 ml graz- er- 1 d- 1. In field experiments performed in September 1991 and March 1992 in Monterey Bay, California, 21-55% of the phytoplankton standing stock was consumed daily by microzooplankton grazing. The underestimation of grazing rates in the laboratory experiments implies that rates obtained in field incubations may be in error., , , Downloaded from: aslo.org/lo/toc/vol_40/issue_4/0827.pdf (16 June 2014).
Author: Waterhouse, Welschmeyer
Date: 1995-01-01T00:00:00Z

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