Symbiosis between the holothurian Scotoplanes sp. A and the lithodid crab Neolithodes diomedeae on a featureless bathyal sediment plain          下载免费PDF全文

James P. Barry  Josi R. Taylor  Linda A. Kuhnz  Andrew P. De Vogelaere 《Marine Ecology》2017,38(2)

Vulnerability to predation may be high for many megafaunal taxa in deep‐sea sedimentary habitats where physical heterogeneity is low. During ROV observations in a bathyal sediment plain off Central California, juveniles of the lithodid crab Neolithodes diomedeae were frequently observed on or under the holothurian (sea cucumber) Scotoplanes sp. A, and are hypothesized to benefit from this association as a nursery or refugium from predation. Ninety‐six percent (n = 574 of 599) of the juvenile N. diomedeae observed (density varied from 0.02–0.75/m² among sites and seasons) in the study area were associated with Scotoplanes sp. A. Of the 2596 Scotoplanes sp. A observed (density varied from 0.48 to 25.90/m²), 22% were attended by at least one juvenile crab, and rarely two crabs (n = 4). Solitary N. diomedeae were rarely observed. This decapod–holothurian symbiosis appears to be largely commensal, with juvenile crabs (carapace width = 0.03–0.31 ×  holothurian length) observed on or beneath Scotoplanes sp. A in a habitat with few refugia from epibenthic predators. Other hypotheses may explain or enhance the potential benefits of the association for N. diomedeae, such as elevated food availability due to the activities of Scotoplanes sp. A. The relationship may be mutualistic if there is a benefit for the holothurian, including the removal of epizoic parasites. Ultimately, the nursery or other effects on the population dynamics of N. diomedeae may be minimal in low‐relief, sediment‐dominated habitats, as very few sub‐adult crabs were observed in the study area and were likely consumed upon outgrowing their refugia. While sedimentary habitats may be a sink for N. diomedeae populations, growth of juvenile crabs during their association with Scotoplanes sp. A should increase energy flow to its predator populations. This association has not been reported previously but may be expected in sediment‐dominated habitats where these species overlap.  相似文献   

<Emphasis Type="Italic">Spartina alterniflora</Emphasis> Biomass Allocation and Temperature: Implications for Salt Marsh Persistence with Sea-Level Rise     

Sarah C. Crosby  Angus Angermeyer  Jennifer M. Adler  Mark D. Bertness  Linda A. Deegan  Nathaniel Sibinga  Heather M. Leslie 《Estuaries and Coasts》2017,40(1):213-223

To predict the impacts of climate change, a better understanding is needed of the foundation species that build and maintain biogenic ecosystems. Spartina alterniflora Loisel (smooth cordgrass) is the dominant salt marsh-building plant along the US Atlantic coast. It maintains salt marsh elevation relative to sea level by the accumulation of aboveground biomass, which promotes sediment deposition and belowground biomass, which accretes as peat. Peat accumulation is particularly important in elevation maintenance at high latitudes where sediment supply tends to be limited. Latitudinal variation in S. alterniflora growth was quantified in eight salt marshes from Massachusetts to South Carolina. The hypothesis that allocation to aboveground and belowground biomass is phenotypically plastic was tested with transplant experiments among a subset of salt marshes along this gradient. Reciprocal transplants revealed that northern S. alterniflora decreased allocation to belowground biomass when grown in the south. Some northern plants also died when moved south, suggesting that northern S. alterniflora may be stressed by future warming. Southern plants that were moved north showed phenotypic plasticity in biomass allocation, but no mortality. Belowground biomass also decomposed more quickly in southern marshes. Our results suggest that warming will lead northern S. alterniflora to decrease belowground allocation and that belowground biomass will decompose more quickly, thus decreasing peat accumulation. Gradual temperature increases may allow for adaptation and acclimation, but our results suggest that warming will lower the ability of salt marshes to withstand sea-level rise.  相似文献   

Preparation and Measurement of Cassiterite for Sn Isotope Analysis          下载免费PDF全文

Ryan Mathur  Wayne Powell  Andrea Mason  Linda Godfrey  Junming Yao  Mark E. Baker 《Geostandards and Geoanalytical Research》2017,41(4):701-707

Increased interest in the fractionation of Sn isotopes has led to the development of several techniques for preparing cassiterite (SnO₂, the primary ore of Sn) for isotopic analysis. Two distinct methods have been applied in recent isotopic studies of cassiterite: (a) reduction to tin metal with potassium cyanide (KCN) at high temperature (800 °C), with subsequent dissolution in HCl, and (b) reduction to a Sn solution with hydriodic acid (HI) at low temperature (100 °C). This study compares the effectiveness and accuracy of these two methods and contributes additional methodological details. The KCN method consistently yielded more Sn (> 70% in comparison with < 5%), does not appear to fractionate Sn isotopes at high temperatures over a 2‐hour period and produced consistent Sn isotope values at flux mass ratios of ≥ 4:1 (flux to mineral) with a minimum reduction time of 40 min. By means of a distillation experiment, it was demonstrated that HI could volatilise Sn, explaining the consistently low yields by this method. Furthermore, the distillation generated Sn vapour, which is up to 0.38‰ per mass unit different from the starting material, the largest induced Sn fractionation reported to date. Accordingly, the HI method is not recommended for cassiterite preparation for Sn isotopic analysis.  相似文献   

Deep-sea faunal communities associated with a lost intermodal shipping container in the Monterey Bay National Marine Sanctuary,CA     

Josi R. Taylor  Andrew P. DeVogelaere  Erica J. Burton  Oren Frey  Lonny Lundsten  Linda A. Kuhnz  P.J. Whaling  Christopher Lovera  Kurt R. Buck  James P. Barry 《Marine pollution bulletin》2014

Carrying assorted cargo and covered with paints of varying toxicity, lost intermodal containers may take centuries to degrade on the deep seafloor. In June 2004, scientists from Monterey Bay Aquarium Research Institute (MBARI) discovered a recently lost container during a Remotely Operated Vehicle (ROV) dive on a sediment-covered seabed at 1281 m depth in Monterey Bay National Marine Sanctuary (MBNMS). The site was revisited by ROV in March 2011. Analyses of sediment samples and high-definition video indicate that faunal assemblages on the container’s exterior and the seabed within 10 m of the container differed significantly from those up to 500 m. The container surface provides hard substratum for colonization by taxa typically found in rocky habitats. However, some key taxa that dominate rocky areas were absent or rare on the container, perhaps related to its potential toxicity or limited time for colonization and growth. Ecological effects appear to be restricted to the container surface and the benthos within ∼10 m.  相似文献   

Outgassing of icy bodies in the Solar System – I. The sublimation of hexagonal water ice through dust layers     

B. Gundlach  Yu.V. Skorov  J. Blum 《Icarus》2011,213(2):710-719

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Geoforensics by Alastair Ruffell and Jennifer McKinley. Wiley‐Blackwell,Chichester, 2008. No. of pages: x+332. Price: UK£32‐50. ISBN 978‐0‐470‐05735‐3 (paperback).     

Malcolm Birtle  Linda Stephenson 《Geological Journal》2011,46(6):660-660

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The application of multivariate statistical methods to phytoplankton counts from the Hauraki Gulf,New Zealand     

Linda Maddock  F. J. Taylor 《新西兰海洋与淡水研究杂志》2013,47(3):309-322

The phytoplankton population from a station in the Jellicoe Channel area of the Hauraki Gulf, New Zealand, was fairly constant, in terms of total population and species composition, throughout the year. Correspondence analysis enabled us to identify 3 groups of species. The largest of these comprised the core species which were present most of the time and included some, such as the coccolithophores, with a strongly seasonal occurrence. The species in the second group were mainly large centric diatoms and appeared for short periods during the winter months, apparently brought in by incursions of oceanic water. The third group of species occurred between April 1970 and October 1971 when there was a period of unusually warm weather: the winds were lighter and more often blowing onshore and this perhaps led to warmer, less nutrient‐rich surface waters being brought into the Gulf.  相似文献   

SVME: an ensemble of support vector machines for detecting oil spills from full resolution MODIS images     

Marco Cococcioni  Linda Corucci  Andrea Masini  Fabio Nardelli 《Ocean Dynamics》2012,62(3):449-467

This paper addresses oil spill detection from remotely sensed optical images. In particular, it focuses on the automatic classification of regions of interest (ROIs) in two classes, namely oil spills or look-alikes. Candidate regions and the corresponding boundaries have been manually identified from full resolution Moderate Resolution Imaging Spectroradiometer images, related to the Mediterranean Sea over the years 2008 and 2009. Then, a set of features has been extracted from each ROI, allowing to formulate the oil spill detection problem as a two-class classification task on the provided regions (i.e. using a supervised learning strategy). Since ROI classification is challenging, some desired characteristics for the classification algorithm are first identified, such as accuracy, robustness, etc. Then, a solution (called SVME) is provided: it is based on an ensemble of incremental/decremental cost-oriented Support Vector Machines, aggregated with the Receiving Operating Characteristic (ROC) convex hull method in the ROC space. Such a solution addresses all the desired characteristics. Finally, the results obtained on the collected dataset are shown. The importance of this study is the devising of a powerful classification technique that may have an impact on optical oil spill detection from space, especially if fused with satellite synthetic aperture radar data. Moreover, it is shown how the proposed system can be used as a decision support tool, to help a junior operator in making more reliable detections.  相似文献   

Evaluating MT3DMS for Heat Transport Simulation of Closed Geothermal Systems     

Jozsef Hecht-Méndez  Nelson Molina-Giraldo  Philipp Blum  Peter Bayer 《Ground water》2010,48(5):741-756

Owing to the mathematical similarities between heat and mass transport, the multi-species transport model MT3DMS should be able to simulate heat transport if the effects of buoyancy and changes in viscosity are small. Although in several studies solute models have been successfully applied to simulate heat transport, these studies failed to provide any rigorous test of this approach. In the current study, we carefully evaluate simulations of a single borehole ground source heat pump (GSHP) system in three scenarios: a pure conduction situation, an intermediate case, and a convection-dominated case. Two evaluation approaches are employed: first, MT3DMS heat transport results are compared with analytical solutions. Second, simulations by MT3DMS, which is finite difference, are compared with those by the finite element code FEFLOW and the finite difference code SEAWAT. Both FEFLOW and SEAWAT are designed to simulate heat flow. For each comparison, the computed results are examined based on residual errors. MT3DMS and the analytical solutions compare satisfactorily. MT3DMS and SEAWAT results show very good agreement for all cases. MT3DMS and FEFLOW two-dimensional (2D) and three-dimensional (3D) results show good to very good agreement, except that in 3D there is somewhat deteriorated agreement close to the heat source where the difference in numerical methods is thought to influence the solution. The results suggest that MT3DMS can be successfully applied to simulate GSHP systems, and likely other systems with similar temperature ranges and gradients in saturated porous media.  相似文献   

Spectra® fishing twine entanglement of a bottlenose dolphin: A case study and experimental modeling     

Susan G. Barco  Linda R. D’Eri  Jeremy P. Winn 《Marine pollution bulletin》2010,60(9):1477-1481

We report here the first documented case of a cetacean fatality from entanglement in recreational Spectra® fishing twine. Spectra® twine is a relatively new microfilament braided twine that is marketed to replace nylon monofilament twine in rod and reel fisheries. Following the case of this entangled bottlenose dolphin (Tursiops truncatus), we conducted tests with Spectra® and comparable monofilament twines on Tursiops tissue from stranded animals to compare the abrasion properties of the twines. We found that Spectra® twine was significantly more abrasive on bottlenose dolphin fluke tissue than a similar strength and diameter monofilament. With the same forces applied, the Spectra® twine cut deeper than the monofilament, exhibiting a linear relationship with force applied where the monofilament appeared to reach a maximum depth of penetration of approximately 2 mm. These tests may explain why this bottlenose dolphin was so severely debilitated from carrying a relatively light load of twine over a short period of time (20 days). Future public and corporate outreach will be essential to minimize the effect that this increasingly popular fishing twine will have on non-target species.  相似文献