Articles

Published journal articles by MLML faculty, staff and students. Full text is included when copyright allows.


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Vertex: Phytoplankton/iron studies in the Gulf of Alaska
Vertex: Phytoplankton/iron studies in the Gulf of Alaska
VERTEX studies were performed in the Gulf of Alaska in order to test the hypothesis that iron deficiency was responsible for the phytoplankton's failure to remove major plant nutrients from these waters. In view of the observed Fe distributions and the results of phytoplankton Fe enrichment experiments, it was concluded that Gulf of Alaska atmospheric Fe input rates are sufficient to support moderately high rates of primary productivity; however, not enough Fe is available to support the high growth rates that would lead to normal major nutrient depletion. Enhanced Fe input does occur along the Alaska continental margin, where normal NO 3 surface depletion is observed. Coccolithophorids appear to be best able to cope with low Fe conditions; however, they cannot compete with diatoms when Fe is readily available. Iron may be more important than available N in determining global rates of phytoplankton new production. Offshore Pacific Ocean water, replete with major nutrients, appears to be infertile without supplemental iron from the atmosphere or continental margin. © 1989., Cited By (since 1996):399
Vertical concentration profiles of lead in the Central Pacific at 15°N and 20°S
Vertical concentration profiles of lead in the Central Pacific at 15°N and 20°S
Concentrations of lead were measured in a surface transect and at two vertical profile stations (15°N and 20°S) in the Central Pacific. These measurements complement similar measurements made earlier in the North Pacific at 33°N and in the Northwest Atlantic at 34°N [1,2], as well as recent measurements of eolian lead input fluxes near each of these locations [3]. The new transect of surface water concentrations of lead corroborates previous measurements, which decrease from 13 ng/kg at 30°N to 4 ng/kg at 17°S in the Central Pacific [4]. This transect gradient is shown to overlie a similar geographic gradient of subsurface maximum concentrations of lead in the three Pacific vertical profile stations, decreasing from 14 ng/kg at 33°N to 11 ng/kg at 14°N to 2.5 ng/kg at 20°S. Lead concentrations at each of those locations exhibit maxima at 400 m, decreasing concentrations to 2500 m and approximately concentrations of 0.8-1.1 ng/kg below that depth. The subsurface maximum at the northwest Atlantic profile station (36 ng/kg at 34°N) is also congruent with surface water lead concentrations which decrease from 806 ng/kg to 32 ng/kg in an offshore transect from Rhode Island to 34°N, 66°W [5], and the shape of the Atlantic profile is congruent with those in the Pacific. There is a positive correlation between the magnitudes of eolian lead input fluxes and the magnitudes of the upper water maxima in lead concentration profiles at corresponding locations as follows: South Pacific easterlies 3 ng/cm2 yr vs. 2.5 ng/kg; North Pacific easterlies 6 ng/cm2 yr vs. 11 ng/kg; North Pacific westerlies 50 ng/cm2 yr vs. 14 ng/kg; and North Atlantic westerlies 170 ng/cm2 yr vs. 36 ng/kg. This relationship enables one to view the anthropogenic perturbations of the marine lead cycle on a global scale, since the industrial origin of eolian and seawater lead has been established by correlations between geographic patterns of industrial lead emissions to the atmosphere and isotopic ratios of industrial leads [3] and by geographic patterns of Pb/silicate-dust ratios and lead isotopic ratios in ocean surface waters [3-5]. These new data coupled with earlier biogeochemical data indicate that surface water concentrations of lead in the North Pacific and North Atlantic are now conservatively estimated to be 8 to 20-fold greater and those in the South Pacific are 2-fold greater than natural concentrations because of industrial emissions of lead to the atmosphere. © 1983., Cited By (since 1996):49
Vertical distribution, transport, and exchange of carbon in the northeast Pacific Ocean: Evidence for multiple zones of biological activity
Vertical distribution, transport, and exchange of carbon in the northeast Pacific Ocean: Evidence for multiple zones of biological activity
A sediment trap experiment was conducted to investigate the production, decomposition, and transport of organic matter from 0 to 2000 m at a station 100 km northeast of Point Sur, California. Parameters measured included (1) rates of autotrophic production of carbon, (2) vertical depth distributions of total carbon, nitrogen, and living biomass, and (3) downward flux of organic carbon, nitrogen, ATP, RNA, and fecal pellets. Metabolic activity and microbial growth rates (RNA and DNA synthesis) were also estimated in situ, for both the 'suspended' (i.e., samples captured in standard water bottles) and 'sinking' (i.e., samples captured in sediment traps) particles. Daily depth-integrated rates of primary production averaged 564 mg C m-2, of which 10 to 15% was removed from the euphotic zone by sinking, assuming steady-state conditions. The profiles of suspended carbon, nitrogen, C:N ratios, and ATP conformed to previously published concentration-depth profiles from the region. The vertical flux profiles of organic matter, however, revealed two important features that were not evident in the suspended particulate matter profiles. First, there was an obvious mid-water depth increase (i.e., an increase in organic carbon and nitrogen flux with increasing depth) between 700 and 900 m, suggesting horizontal advection or in situ production. Similar flux profiles were also observed for ATP, RNA, and total fecal pellets. Second, the C:N ratios for the sediment trap materials collected at mid-ocean depths (600 to 1200 m) were low compared to values measured for 'suspended' particulate organic materials collected from comparable depths, supporting the in situ production hypothesis. An observed maximum in the rate of RNA and DNA synthesis for microorganisms associated with particles collected at 700 m confirmed that the flux anomalies were the result of in situ microbiological processes rather than horizontal advection. We hypothesize that the in situ activity measured at 700 m is the result of a chemolithotrophic-based carbon production system supported by the presence of reduced inorganic compounds (e.g., NH4+, HS-) found in association with the sinking particles. "New carbon production" (a value equivalent to the increased downward flux of carbon) between 700 and 900m was 15 mg C m-2 d-1, or 2 to 1% of the daily integrated primary production. These regions of intense biological metabolic activity, growth, and organic matter diagenesis may have a profound influence on the oceanic carbon cycle and on the observed steady-state distributions of various non-conservative properties of seawater. © 1984., Cited By (since 1996):51
Vertical distributions and relations of euphausiid populations off Elephant Island, March 1984
Vertical distributions and relations of euphausiid populations off Elephant Island, March 1984
Distributional relationships are described for post-larval and larval Euphausia superba and Thysanoessa sp. (probably macrura) and post-larval Euphausia frigida collected in 0-70/80 m and 0-175/200 m depth ranges with a MOCNESS sampler north of Elephant Island (61°S, 55°W) during 17-23 March 1984. Larval E. superba (predominantly calyptopes stage 2 and 3) were rare shallower than 80 m at night. Day catches of post-larval E. suberba were small and night catches were primarily near the top of the thermocline above 50 m depth. Thysanoessa sp. occurred throughout the 0-200 m depth range and was abundant in the upper 80 m both night and day. E. frigida migrated to the upper 80 m at night from deeper day depths. Larval stages of E. superba and bost-larval stages of all three species demonstrated independent and variable vertical distribution patterns both night and day. Changes in E. superba abundance and distributional patterns could to a certain extent be associated with observed environmental changes. An increase in larval and decrease in post-larval E. superba abundances between 0-80 m was associated with an intrusion of cold water at depth. At night, vertically restricted concentrations of post-larval E. superba were associated with shallow mixed layer depths, and a significant vertical separation of developmental stages and size categories was observed only during periods of stratification in the upper 80 m. Fluctuations in the distribution and abundance of Thysanoessa sp. and distribution of E. frigida did not appear to be influenced by physical parameters within the upper 80 m. Within the 0-80 m depth range, the distributions of these two species differed from each other and from E. superba and showed large tow to tow variability that could not be related to physical parameters in the upper water column. © 1987 Springer-Verlag., Cited By (since 1996):8, CODEN: POBID
Vital stain in bait as a tag
Vital stain in bait as a tag
This study evaluated the use of various vital stains and tetracycline placed in bait to mark fish in situ. The procion dye, reactive red 8, was the only stain detectable after 11 weeks; tetracycline was not detected in the otoliths.
Walkers Cay Fault, Bahamas: Evidence for Cenozoic faulting
Walkers Cay Fault, Bahamas: Evidence for Cenozoic faulting
Interpretation of seismic reflection data reveal evidence of a Cenozoic fault (Walkers Cay Fault) north of Little Bahama Bank. This fault strikes N15-30°E, perpendicular to the adjacent bank margin and offsets a late Oligocene reflector by as much as 100 m. The origin of this near-surface fault is uncertain, but its location and strike are nearly coincident with an independently mapped basement fault. Walkers Cay Fault may be the result of recurrent faulting, implying intermittent basement fault movement during the post-rift history of the northern Bahamian continental margin. © 1981 A.M. Dowden, Inc., Cited By (since 1996):2, CODEN: GMLED
Walrus feeding disturbance: Scavenging habits and recolonization of the Bering Sea benthos
Walrus feeding disturbance: Scavenging habits and recolonization of the Bering Sea benthos
Walruses (Odobenus rosmarus Illiger) influenced the structure of macrobenthic assemblages in a variety of ways as they excavated their major bivalve prey from soft sediments. Benthic animals were attracted to discarded bivalve shells and they colonized pits and furrows made during prey excavation. Discarded shells contained soft tissues that were eaten by several invertebrate scavengers. The most abundant and widespread scavenger was the sea star, Asterias amurensis Lutken. Sea stars out-competed brittle stars (Amphiodia craterodmeta Clark) for fresh scavenging events. They also attacked brittle stars under shells in the laboratory, and thus may have obtained two meals from discarded shells by eating remnant tissue and by consuming animals that used the shell as a habitat. In nature, brittle stars were abundant under discarded shells. In experiments, brittle stars invaded shells with soft tissue in the absence of sea stars, but not in their presence. In other experiments, brittle stars were most abundant under shells with soft tissue, but were also attracted to shells without organic matter. Large brittle stars were more abundant under shells than in the surrounding bottom, and the reverse was true of small individuals. Bottom communities recovered gradually inside experimental feeding excavations, which were not invaded by large numbers of opportunistic infaunal or epifaunal invertebrates. This is in contrast to gray whale feeding excavations, which are colonized by a large number of opportunistic peracarid crustaceans. © 1985., Cited By (since 1996):32, CODEN: JEMBA
Warmer temperatures reduce the influence of an important keystone predator
Warmer temperatures reduce the influence of an important keystone predator
Predator-prey interactions may be strongly influenced by temperature variations in marine ecosystems. Consequently, climate change may alter the importance of predators with repercussions for ecosystem functioning and structure. In North-eastern Pacific kelp forests, the starfish Pycnopodia helianthoides is known to be an important predator of the purple sea urchin Strongylocentrotus purpuratus. Here we investigated the influence of water temperature on this predator-prey interaction by: (1) assessing the spatial distribution and temporal dynamics of both species across a temperature gradient in the northern Channel Islands, California, and (2) investigating how the feeding rate of P. helianthoides on S. purpuratus is affected by temperature in laboratory tests. On average, at sites where mean annual temperatures were <14°C, P. helianthoides were common, S. purpuratus was rare and kelp was persistent, whereas where mean annual temperatures exceeded 14°C, P. helianthoides and kelp were rare and S. purpuratus abundant. Temperature was found to be the primary environmental factor influencing P. helianthoides abundance, and in turn P. helianthoides was the primary determinant of S. purpuratus abundance. In the laboratory, temperatures >16°C (equivalent to summer temperatures at sites where P. helianthoides were rare) reduced predation rates regardless of predator and prey sizes, although larger sea urchins were consumed only by large starfishes. These results clearly demonstrate that the effect of P. helianthoides on S. purpuratus is strongly mediated by temperature, and that the local abundance and predation rate of P. helianthoides on sea urchins will likely decrease with future warming. A reduction in top-down control on sea urchins, combined with other expected impacts of climate change on kelp, poses significant risks for the persistence of kelp forests in the future.
Water quality assessment in the Mexican Caribbean: Impacts on the coastal ecosystem
Water quality assessment in the Mexican Caribbean: Impacts on the coastal ecosystem
Coastal zones are dominated by economically important ecosystems, and excessive urban, industrial, agricultural, and tourism activities can lead to rapid degradation of those habitats and resources. Groundwater in the Eastern Yucatan Peninsula coastal aquifer discharges directly into the coastal ocean affecting the coral reefs, which are part of the Mesoamerican Coral Reef System. The composition and impacts of groundwater were studied at different coastal environments around Akumal (SE Yucatan Peninsula). Radium isotopes and salinity were used to quantify fresh groundwater and recirculated seawater contributions to the coastal zone. Excess Ra distribution suggests spatially variable discharge rates of submarine groundwater. High NO3- levels and high coliform bacteria densities indicate that groundwater is polluted at some sites. Dissolved phosphorous content is elevated in the winter and during the high tourism season, likely released from untreated sewage discharge and from aquifer sediments under reducing conditions.
What are algal turfs?: Towards a better description of turfs
What are algal turfs?: Towards a better description of turfs
The use of standardised classifications, or operational definitions, is essential if different researchers are to measure and compare similar entities. In the marine realm, algal 'turfs' are increasingly reported to be globally expanding at the expense of kelps and canopy-forming algae. However, ecological research about the underlying drivers of this shift is limited by a vague and inconsistent definition of what exactly a turf is. In order to stimulate more effective descriptions of 'turfs' and facilitate communication of research outcomes and comparisons across studies, we reviewed the use of the term turf in ecological studies of temperate coasts and coral reefs and (1) identified the main types and distribution of algal assemblages known as 'turfs', (2) examined the descriptions of turfs so that we may recognise some general characteristics, including those contingent on environmental conditions; and (3) offered character descriptions that could improve communication and comparisons. These descriptors centre on reporting information on the morphology, height, density of thalli, the amount of sediment trapped in turfs and a description of the area covered by turfs, including their patchiness and persistence. Our review recognised these as common attributes that could be usefully described across a wide range of circumstances and provide insights into the ecology of turfs and their interactions with other assemblages in a community. The use of common descriptors would provide the term 'turf' with greater scientific value. © Inter-Research 2014., Seaweeds
What controls dissolved iron concentrations in the world ocean?
What controls dissolved iron concentrations in the world ocean?
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
What do we really know about marine biodiversity in central California?
What do we really know about marine biodiversity in central California?
This is a brief overview of what is known about marine biodiversity in the central California coastal region. The term biodiversity has become very popular, but detailed knowledge is often lacking, especially in the ocean. Although much information on the flora and fauna of this coast exists in the form of books, guides and the scientific literature, some habitats are still poorly understood. Marine ecosystems can be divided into: 1) well known, 2) moderately known, and 3) poorly known systems. These categories in general follow a gradient from shallow, coastal habitats to deeper, offshore areas. Marine biologists have an idea which factors are associated with high or low biodiversity, and those that act as threats to it. However, basic information on which species occupy specific habitats, especially those in deeper water, is often lacking. To better understand marine biodiversity, we need to develop and deploy non-destructive survey techniques, increase training of taxonomists, increase support for museums, produce more comprehensive taxonomic aids, and undertake more intensive and long-term surveys of marine ecosystems. Cooperative efforts among state and federal reserves, refuges, preserves, and sanctuaries, specifically the Gulf of the Farallones, Cordell Bank, Monterey Bay and Channel Island National Marine Sanctuaries, can result in major advances in our understanding and preservation of marine biodiversity., Cited By (since 1996):1, CODEN: 00310
What sharks can tell us about the evolution of MHC genes
What sharks can tell us about the evolution of MHC genes
Similarity in structural features would argue that sharks possess class I, class IIA and class IIB genes, coding for classical peptide-presenting molecules, as well as non-classical class I genes. Some aspects of shark major histocompatibility complex genes are similar to teleost genes and others are similar to tetrapod genes. Shark class I genes form a monophyletic group, as also seen for tetrapods, but the classical and nonclassical genes form two orthologous clades, as seen for teleosts. Teleost class I genes arose independently at least four different times with the nonclassical genes of ray-finned fishes and all the shark and lobe-finned fish class I genes forming 1 clade. The ray-finned fish classical class I genes arose separately. In phylogenetic trees of class II α2 and β2 domains, the shark and tetrapod genes cluster more closely than the teleost genes and, unlike the teleost sequences, the class II α1 domains of sharks and tetrapods lack cysteines. On the other hand, both shark and teleost genes display sequence motifs in the antigen-binding cleft that have persisted over very long time periods. The similarities may reflect common selective pressures on species in aqueous environments while differences may be due to different evolutionary rates., Cited By (since 1996):19, CODEN: IMRED
What's happening in Monterey Bay on seasonal to interdecadal time scales
What's happening in Monterey Bay on seasonal to interdecadal time scales
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
Whisker growth dynamics in two North Pacific pinnipeds: Implications for determining foraging ecology from stable isotope analysis
Whisker growth dynamics in two North Pacific pinnipeds: Implications for determining foraging ecology from stable isotope analysis
Cited By :1, Stable isotope analysis (SIA) of whiskers is increasingly used to investigate the foraging ecology of pinnipeds. An understanding of whisker growth dynamics is lacking for most species yet is necessary for study design and interpretation of isotope data. Here we present measurements of whisker growth obtained using photogrammetry in 5 California sea lions Zalophus californianus and 2 spotted seals Phoca largha. Data were collected from captive individuals for at least 1 yr, resulting in serial measurements of 321 sea lion and 153 spotted seal whiskers. The sea lion whiskers exhibited linear growth, with growth rates that ranged from <0.01 to 0.18 mm d-1. In contrast, spotted seal whiskers exhibited asymptotic growth characterized by rapid initial growth of up to 1.40 mm d-1; whiskers reached 75 and 95% of their asymptotic length after an average of 48 and 105 d, respectively. Over half of the spotted seal whiskers were lost annually during a period that coincided with the annual pelage molt, whereas the maximum estimated lifespan of sea lion whiskers was 10+ yr. Our data indicate that sea lion whisker growth rates can be used to reliably determine time periods of tissue deposition and link isotope values with ecological events over multiple years. In contrast, spotted seal whiskers archive dietary information over a period of months, and interpretation of isotope values is complicated by growth and shedding patterns of whiskers, and physiological changes associated with the annual pelage molt.
White shark strike on a long-range AUV in Monterey Bay
White shark strike on a long-range AUV in Monterey Bay
Thirteen minutes after sunrise on September 30, 2013,16.5 m deep in northern Monterey Bay, a white shark (Car-charodon carcharias) struck the MBARI long-range autonomous underwater vehicle (LRAUV) Tethys and left bite grooves in the pressure vessel and tooth fragments embedded in the aft fairing. Tethys survived the attack and continued her mission measuring ocean properties in that area for another week. The operators did not know about the strike until recovering the vehicle normally at the end of the deployment, when the tooth fragments and apparent bite diameter provided sufficient information to identify the shark species. We discuss the motion of the vehicle during the strike, its control response after being released by the shark, and the environmental properties it measured near the time of the strike. We also provide a damage report - although Tethys was able to complete her mission after the strike, she did not get away without a scratch. This event is a good example for recent work aimed at detecting faults and performance anomalies onboard in realtime so that operators can be notified. We show that a statistical anomaly detector correctly identifies the strike and effectively highlights it as unexpected behavior for the operator to review. © 2015 IEEE., Export Date: 19 February 2016, Conference Paper
Why do satellite transmitters on emperor penguins stop transmitting?
Why do satellite transmitters on emperor penguins stop transmitting?
Investigation of early transmission failure from animal-borne, satellite transmitters should reveal vital information about the reliability of the technology, and the risk of application to the animal. Current technology available to the investigator does not provide firm evidence for causes of transmitter blackout. We address the five most likely causes of satellite transmitter failure on 20 adult (10 male and 10 female) emperor penguins tagged near Cape Colbeck, Antarctica, and one near the Drygalski Ice Tongue, Western Ross Sea, during late summer, 2013. They are: 1. Technical failure of the transmitter, 2. Instrument breakage, 3. Instrument loss because of attachment failure, 4. Predation, and 5. Icing of the salt water detection switch. The longest record of 323 days suggests that prior losses were not due to power failure. Various possibilities of transmission blackout are discussed, and we speculate about the most likely causes of termination of transmissions. A loss of transmission from six tags at similar locations early in the deployments suggests predation. Later losses at random times and locations may be because of antenna breakage or attachment failure. Definite conclusions cannot be made because of the indirect assessment of transmission loss. We suggest some changes in deployment procedures to improve our ability to determine cause of satellite transmission termination in the future. Understanding causes of blackout is important both scientifically and ethically in terms of accurate data interpretation and balancing the benefits of scientific gain with the costs of animal disturbance.
Widespread fluid expulsion on a translational continental margin: Mud volcanoes, fault zones, headless canyons, and organic-rich substrate in Monterey Bay, California
Widespread fluid expulsion on a translational continental margin: Mud volcanoes, fault zones, headless canyons, and organic-rich substrate in Monterey Bay, California
Remotely operated vehicle (ROV)-based mapping of tectonic features, zones of anomalous reflectivity, and geomorphic targets in Monterey Bay, California, demonstrates the regional abundance of fluid expulsion along the active transform margin between the Pacific and North American plates. Cold seeps - extant communities characterized by chemosynthetic bivalves, bacterial mats, and rare tubeworms - are the surface manifestations of present-day fluid expulsion of sulfide- and methane-rich fluids, whereas slabs, veins, and chimneys of authigenic carbonate represent regions of either dormant methane-rich fluid expulsion, or areas where the present rate of flow is too low to support chemosynthetic fauna. We have found both active and dormant fluid seepage along fault zones, at the surface expression of mud volcanoes, on organic-rich or permeable substrate, and within headless canyons across a wide range of depths within Monterey Bay. The fluid egress at these sites may be driven by a combination of (1) pore-space reduction caused by rapid sedimentation and/or tectonic compaction related to residual Pacific-North America compression, and (2) increased buoyancy due to a decrease in pore-fluid density related to diagenesis and/or catagenesis at depth. Although provocative, the relationship between topographically driven aquifer discharge and sea-floor fluid expulsion remains speculative for Monterey Bay. The widespread distribution of fluid expulsion features controlled by a variety of conduits in Monterey Bay implies that cold seeps may be common features on translational margins., Cited By (since 1996):60, CODEN: BUGMA
Zoom! Remote sensing imagery in the geosciences
Zoom! Remote sensing imagery in the geosciences
The first International Polar Year took place in 1882 and 1883, before the rise in greenhouse gas pollution associated with global climate change. Carl Weyprecht, an Austrian scientist-explorer who was the inspiration behind the IPY, had forward thinking ideas about how to most profitably conduct polar research. In his Fundamental Principals of Scientific Arctic Investigation he proposed fielding coordinated expeditions that would collect comparable synoptic observations necessary to study very large-scale phenomena such as meteorology, geomagnetism and the aurora. The field program he suggested was successfully implemented but the hard-won synoptic observations were never fully analyzed. Long delays in the initial publication of the data and the lack of a central office tasked with coordinating data synthesis contributed to this disappointing result. The fourth IPY began in March, 2007. Climate change, especially in the Arctic, adds urgency to the objective of taking a “snapshot” of current conditions using synoptic observations. And making observations accessible to everyone is proper not only because the public is aware and interested, but because to do so would help ensure that exceeding valuable data is used to its fullest potential. Now IPY research involves over 50,000 participants from 63 nations. How much of this research will be accessible in the future? What can be done to promote the flow and preservation of information? Are there lessons in data management from the first IPY than can be applied here? Now, web services, distributed data archives and metadata standards are being employed to keep track of and work with data from ‘virtual observatories': confederations of projects and instrumentation like the National Science Foundation's Arctic Observing Network. Metadata can insure that future generations will be able to find the data. So many types of data from so many sources is driving a move to self-describing data formats. In an age where most data are ‘born digital' we still need to go back and preserve old analog data so that it can be used to investigate phenomena such as the Earth's climate that vary on timescales longer than the digital era.
Zooplankton fecal pellet fluxes and vertical transport of particulate organic material in the pelagic environment
Zooplankton fecal pellet fluxes and vertical transport of particulate organic material in the pelagic environment
Fecal pellet fluxes were determined using a series of multireplicate traps set at 35, 65, 150, 500, 750 and 1500 m in the northeast Pacific.Fecal pellets appear to be important contributors to total carbon fluxes. In near-surface waters (35-150 m), pellet fluxes ranged from 2-3 × 105 pellets m-2 day-1. Minimum pellet fluxes were observed at 500m(̃0.4× 105 pellets m-2day-1). In contrast, the 1500 m pellet flux value increased to approximately 0.8 × 105 pellets m-2 day-1 relative to the 500 m depth, and is probably the result of in situ repackaging. Analyses of pellet content suggest multiple sources of "large" particle input throughout the water column. The implications of this phenomenon are discussed in terms of the detrital rain and ladder of migration theories. © 1981 IRL Press Limited., Cited By (since 1996):51, CODEN: JPLRD
Zooplankton invasions: A brief review, plus two case studies from the northeast Pacific Ocean
Zooplankton invasions: A brief review, plus two case studies from the northeast Pacific Ocean
Invasions of aquatic habitats by non-indigenous species (NIS), including zooplankton, are occurring at an alarming rate and are causing global concern. Although hundreds of such invasions have now been documented, surprisingly little is known about the basic biology and ecology of these invaders in their new habitats. Here we provide an overview of the published literature on NIS zooplankton, separated by life history (holoplankton vs. meroplankton), habitat (marine, estuarine, freshwater), and biological level of organization or topic (e.g. distribution and range extension, physiology, behavior, feeding, community impacts, ecosystem dynamics, etc). Amongst the many findings generated by our literature search, perhaps the most striking is the paucity of studies on community and ecosystem level impacts of NIS zooplankton, especially in marine and estuarine systems. We also present some results from two ongoing studies of invasive zooplankton in the northeast Pacific Ocean - Pseudodiaptomus inopinus in Washington and Oregon coastal estuaries, and Tortanus dextrilobatus in San Francisco Bay. Both of these Asian copepods have recently expanded their range and can at times be extremely abundant (103 m-3). We also examine some aspects of the trophic (predator-prey) ecology of these two invasive copepods, and find that they are likely to be important in the flow of material and energy in the systems in which they now pervade, although their impacts at the ecosystem level remain to be quantified. Finally, the findings of both our literature search and our two case studies of invasive zooplankton lead us to make several recommendations for future research., Cited By (since 1996):52, CODEN: HYDRB

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