Articles

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


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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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