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  • 1
    Digitale Medien
    Digitale Medien
    Natural proportions (2004)
    [s.l.] : Nature Publishing Group
    Nature 431 (2004), S. 131-131 
    Details
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] ...An interesting empirical observation in biology is the relationship between the elemental composition of organisms and ecosystems. All organisms are composed primarily of a mixture of six major elements: hydrogen, carbon, nitrogen, oxygen, phosphorus and sulphur. But the proportion of these ...
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1038/431131a
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  • 2
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    Focus detection from digital in-line holograms based on spectral l1 norms (2007)
    Details
    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © Optical Society of America, 2007. This is the author's version of the work. It is posted here by permission of Optical Society of America for personal use, not for redistribution. The definitive version was published in Journal of the Optical Society of America A, 24 (2007): 3054-3062, doi:10.1364/JOSAA.24.003054.
    Beschreibung: In this paper a rapid focus detection technique is developed for objects imaged using digital in-line holograms. It differs from previous approaches in that it is based directly on the spectral content of the object images and does not need a full reconstruction of the actual images. It is based on new focus metrics defined as the l1 norms of the object spectral components associated with the real and imaginary parts of the reconstruction kernel. Furthermore, these l1 norms can be computed efficiently in the frequency domain using a polar coordinate system, yielding a drastic speedup of about two orders of magnitude compared with image-based focus detection. The subsequent reconstruction, when done selectively over these detected focus distances, leads to significant computational savings. Focus detection results from holograms of plankton are demonstrated showing that the technique is both accurate and robust.
    Repository-Name: Woods Hole Open Access Server
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  • 3
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    Biological structure and seasonality in the Japan/East Sea (2009)
    Oceanography Society
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    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © Oceanography Society, 2006. This article is posted here by permission of Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 19, 3 (2006): 122-133.
    Beschreibung: The Japan/East Sea (JES) contains several oceanic regions separated by dynamic boundaries. These distinct regions, and the physical features that establish and maintain the boundaries between the regions, have significant impacts on its ocean biology. Until recently, most studies of the biology of the JES have focused on nearshore regions, with few detailed studies of the interior of the JES or the dynamic features that define the different regions. In addition, the classic sampling methods used in previous work have not allowed high-resolution studies of biological-physical interactions associated with key dynamic mesoscale frontal zones, quasi-synoptic surveys of water column and biological structure in three dimensions, or broad-scale description of the seasonal cycles in the different biogeographic regions of the JES.
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  • 4
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    Accurate automatic quantification of taxa-specific plankton abundance using dual classification with correction (2011)
    Inter-Research
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    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © Inter-Research, 2006. This article is posted here by permission of Inter-Research for personal use, not for redistribution. The definitive version was published in Marine Ecology Progress Series 306 (2006): 51-61, doi:10.3354/meps306051.
    Beschreibung: Optical imaging samplers are becoming widely used in plankton ecology, but image analysis methods have lagged behind image acquisition rates. Automated methods for analysis and recognition of plankton images have been developed, which are capable of real-time processing of incoming image data into major taxonomic groups. The limited accuracy of these methods can require significant manual post-processing to correct the automatically generated results, in order to obtain accurate estimates of plankton abundance patterns. We present here a dual-classification method in which each plankton image is first identified using a shaped-based feature set and a neural network classifier, and then a second time using a texture-based feature set and a support vector machine classifier. The plankton image is considered to belong to a given taxon only if the 2 identifications agree; otherwise it is labeled as unknown. This dual-classification method greatly reduces the false positive rate, and thus gives better abundance estimation in regions of low relative abundance. A confusion matrix is computed from a set of training images in order to determine the detection and false positives rates. These rates are used to correct abundances estimated from the automatic classification results. Aside from the manual sorting required to generate the initial training set of images, this dual-classification method is fully automatic and does not require subsequent manual correction of automatically sorted images. The resulting abundances agree closely with those obtained using manually sorted results. A set of images from a Video Plankton Recorder was used to evaluate this method and compare it with previously reported single-classifier results for major taxa.
    Beschreibung: The work was funded by National Science Foundation Grants OCE-9806498, OCE-9820099, and OCE-0000570.
    Schlagwort(e): Plankton ; Video ; Sampling ; Pattern recognition ; Real-time ; Rejection
    Repository-Name: Woods Hole Open Access Server
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  • 5
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    The depth-distribution of nitrogen fixation by Trichodesmium spp. colonies in the tropical–subtropical North Atlantic (2015)
    Elsevier
    Details
    Publikationsdatum: 2022-05-25
    Beschreibung: © The Author(s), 2015. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Deep Sea Research Part I: Oceanographic Research Papers 104 (2015): 72-91, doi:10.1016/j.dsr.2015.06.012.
    Beschreibung: Nitrogen fixation is an important yet still incompletely constrained component of the marine nitrogen cycle, particularly in the subsurface. A Video Plankton Recorder (VPR) survey in the subtropical North Atlantic found higher than expected Trichodesmium colony abundances at depth, leading to the hypothesis that deep nitrogen fixation in the North Atlantic may have been previously underestimated. Here, Trichodesmium colony abundances and modeled nitrogen fixation from VPR transects completed on two cruises in the tropical and subtropical North Atlantic in fall 2010 and spring 2011 were used to evaluate that hypothesis. A bio-optical model was developed based on carbon-normalized nitrogen fixation rates measured on those cruises. Estimates of colony abundance and nitrogen fixation were similar in magnitude and vertical and geographical distribution to conventional estimates in a recently compiled climatology. Thus, in the mean, VPR-based estimates of volume-specific nitrogen fixation rates at depth in the tropical North Atlantic were not inconsistent with estimates derived from conventional sampling methods. Based on this analysis, if Trichodesmium nitrogen fixation by colonies is underestimated, it is unlikely that it is due to underestimation of deep abundances by conventional sampling methods.
    Beschreibung: We gratefully acknowledge support of this research by NSF and NASA. A NASA Earth and Space Science Fellowship supported E. Olson's graduate studies.
    Schlagwort(e): Nitrogen fixation ; Trichodesmium spp. ; North Atlantic ; Video Plankton Recorder
    Repository-Name: Woods Hole Open Access Server
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  • 6
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    Climate impacts on zooplankton population dynamics in coastal marine ecosystems (2014)
    The Oceanography Society
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    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © The Oceanography Society, 2013. This article is posted here by permission of The Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 26, no. 4 (2013): 34–51, doi:10.5670/oceanog.2013.74.
    Beschreibung: The 20-year US GLOBEC (Global Ocean Ecosystem Dynamics) program examined zooplankton populations and their predators in four coastal marine ecosystems. Program scientists learned that environmental controls on zooplankton vital rates, especially the timing and magnitude of reproduction, growth, life-cycle progression, and mortality, determine species population dynamics, seasonal and spatial distributions, and abundances. Improved knowledge of spatial-temporal abundance and distribution of individual zooplankton taxa coupled with new information linking higher trophic level predators (salmon, cod, haddock, penguins, seals) to their prey yielded mechanistic descriptions of how climate variation impacts regionally important marine resources. Coupled ecological models driven by improved regional-scale climate scenario models developed during GLOBEC enable forecasts of plausible future conditions in coastal ecosystems, and will aid and inform decision makers and communities as they assess, respond, and adapt to the effects of environmental change. Multi-region synthesis revealed that conditions in winter, before upwelling, or seasonal stratification, or ice melt (depending on region) had significant and important effects that primed the systems for greater zooplankton population abundance and productivity the following spring-summer, with effects that propagated to higher trophic levels.
    Beschreibung: For support in the preparation of this manuscript, HPB and WTP acknowledge OCE-0816358; KLD acknowledges OPP-9910610, OPP-0196489, and OCE-0814405; CSD and RJ acknowledge NA17RJ1223 and OCE-0815838; MDO acknowledges the California Current Ecosystem LTER site; and JAR acknowledges OCE-1235920.
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    Materialart: Article
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  • 7
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    Habitat usage by the cryptic copepods Pseudocalanus moultoni and P. newmani on Georges Bank (Northwest Atlantic) (2016)
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    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © The Author(s), 2015. This is the author's version of the work. It is posted here for personal use, not for redistribution. The definitive version was published in Continental Shelf Research 111 (2015): 83-94, doi:10.1016/j.csr.2015.11.001.
    Beschreibung: The cryptic copepod species, Pseudocalanus moultoni and P. newmani, co-occur on Georges Bank and in the Gulf of Maine (Northwest Atlantic); even recent studies have reported results and conclusions based on examination of the combined species. Species-specific PCR (SS-PCR) based on mitochondrial cytochrome oxidase I (COI) sequence divergence was used in this study to discriminate the species. Species-specific descriptions of habitat usage and predicted patterns of transport and retention on Georges Bank were made by mapping distributions and calculating abundances of each species from January to June, 1999 for four vertical strata (0-15 m, 15-40 m, 40-100 m, and 0-100 m) and five regions (Northern Flank, Bank Crest, Northeast Peak, Southern Flank, and Slope Water) identified on the basis of bathymetry and circulation. Patterns of distribution and abundance for the two species during January to June, 1999 were largely consistent with those described based on vertically integrating mapping and analysis for the same period in 1997 by McGillicuddy and Bucklin (2002). The region-specific and depth-stratified analyses allowed further discrimination in habitat usage by the species and confirmed the distinctive patterns for the two species. The observed differences between the species in abundances among the five regions and three depth strata over Georges Bank impact their transport trajectories. The concentration of P. moultoni in deep layers likely explains the higher rates of retention and lower rates of advective loss of this species from the Bank, compared to P. newmani, which may be more subject to wind-driven transport in the surface layer. Accurate identification and discrimination of even closely-related and cryptic species is needed to ensure full understanding and realistic predictions of changes in diversity of zooplankton and the functioning of pelagic ecosystems.
    Beschreibung: Funding was provided by the National Science Foundation as part of the U.S. GLOBEC Program (Award Nos. OCE-9529100 and OCE-9632840 to Ann Bucklin; Award No. OCE-0815047 to Dennis McGillicuddy).
    Schlagwort(e): Zooplankton ; Georges Bank ; Cryptic species ; COI ; Pseudocalanus
    Repository-Name: Woods Hole Open Access Server
    Materialart: Preprint
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  • 8
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    RAPID : research on automated plankton identification (2009)
    Oceanography Society
    Details
    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © Oceanography Society, 2007. This article is posted here by permission of Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 20, 2 (2007): 172-187.
    Beschreibung: When Victor Hensen deployed the first true plankton1 net in 1887, he and his colleagues were attempting to answer three fundamental questions: What planktonic organisms are present in the ocean? How many of each type are present? How does the plankton’s composition change over time? Although answering these questions has remained a central goal of oceanographers, the sophisticated tools available to enumerate planktonic organisms today offer capabilities that Hensen probably could never have imagined.
    Beschreibung: This material is based upon work supported by the National Science Foundation under Grants OCE-0325018, OCE-0324937, OCE-0325167 and OCE-9423471, and the European Union under grants Q5CR-2002-71699, MAS3-ct98-0188, and MAS2-ct92-0015.
    Repository-Name: Woods Hole Open Access Server
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  • 9
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    A simplified age-stage model for copepod population dynamics (2012)
    Inter-Research
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    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © Inter-Research, 2008. This article is posted here by permission of Inter-Research for personal use, not for redistribution. The definitive version was published in Marine Ecology Progress Series 360 (2008): 179-187, doi:10.3354/meps07314.
    Beschreibung: Complex 3D biological-physical models are becoming widely used in marine and freshwater ecology. These models are highly valued synthesizing tools because they provide insights into complex dynamics that are difficult to understand using purely empirical methods or theoretical analytical models. Of particular interest has been the incorporation of concentration-based copepod population dynamics into 3D physical transport models. These physical models typically have large numbers of grid points and therefore require a simplified biological model. However, concentration-based copepod models have used a fine resolution age-stage structure to prevent artificially short generation times, known as numerical ‘diffusion.’ This increased resolution has precluded use of age-stage structured copepod models in 3D physical models due to computational constraints. In this paper, we describe a new method, which tracks the mean age of each life stage instead of using age classes within each stage. We then compare this model to previous age-stage structured models. A probability model is developed with the molting rate derived from the mean age of the population and the probability density function (PDF) of molting. The effects of temperature and mortality on copepod population dynamics are also discussed. The mean-age method effectively removes the numerical diffusion problem and reproduces observed median development times (MDTs) without the need for a high-resolution age-stage structure. Thus, it is well-suited for finding solutions of concentration-based zooplankton models in complex biological-physical models.
    Beschreibung: This work was supported by US GLOBEC NOAA grant NA17RJ1223.
    Beschreibung: 2013-05-22
    Schlagwort(e): Plankton ; Copepods ; Modeling ; Marine ecology ; Oceanography ; Limnology ; Methodology ; Mean age
    Repository-Name: Woods Hole Open Access Server
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  • 10
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    Interannual differences in larval haddock survival : hypothesis testing with a 3D biophysical model of Georges Bank (2015)
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    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © The Author(s), 2014. This is the author's version of the work. It is posted here by permission of John Wiley & Sons for personal use, not for redistribution. The definitive version was published in Fisheries Oceanography 23 (2014): 521–553, doi:10.1111/fog.12087.
    Beschreibung: The ultimate goal of early life studies of fish over the past century has been to better understand recruitment variability. As evident in the Georges Bank haddock (Melanogrammus aeglefinus) population, there is a strong relationship between recruitment success and processes occurring during the planktonic larval stage. This research sought new insights into the mechanisms controlling the recruitment process in fish populations by using biological-physical modeling methods together with laboratory and field data sets. We created the first three-dimensional model of larval haddock on Georges Bank by coupling models of hydrodynamics, lower trophic levels, a single copepod species, and larval haddock. Interactions between feeding, metabolism, growth, vertical behavior, advection, predation, and the physical environment of larval haddock were quantitatively investigated using the coupled models. Particularly, the model was used to compare survival over the larval period and the sources of mortality in 1995 and 1998, two years of disparate haddock recruitment. The results of model simulations suggest that the increased egg hatching rates and higher food availability, which reduced starvation and predation, in 1998 contributed to its larger year-class. Additionally, the inclusion of temperature-dependent predation rates produced model results that better agreed with observations of the mean hatch date of survivors. The results from this biophysical model imply that food-limitation and its related losses to starvation and predation, especially from hatch to 7 mm, may be responsible for interannual variability in recruitment and larval survival outside of the years studied.
    Beschreibung: Financial support was provided by a WHOI Watson Fellowship, a WHOI Coastal Ocean Institute Student Research Proposal Award, and GLOBEC grants NA17RJ1223 (NOAA) and OCE0815838 (NSF).
    Beschreibung: 2015-11-15
    Schlagwort(e): Larval fish ; Individual-based model ; Recruitment ; GLOBEC
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