Target-strength measurements of Pacific hake (Merluccius productus) in Canadian waters using quasi-ideal and conventional beam transducers     

Hamano  Akira; Sasakura  Toyoki; Kieser  Robert; Cooke  Ken; Kubota  Katsuhiko; Clay  Allen 《ICES Journal of Marine Science》1996,53(2):273-279

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<Emphasis Type="Italic">Deepwater Horizon</Emphasis> Oil Spill Impacts on Salt Marsh Fiddler Crabs (<Emphasis Type="Italic">Uca</Emphasis> spp.)     

Scott Zengel  Steven C. Pennings  Brian Silliman  Clay Montague  Jennifer Weaver  Donald R. Deis  Michelle O. Krasnec  Nicolle Rutherford  Zachary Nixon 《Estuaries and Coasts》2016,39(4):1154-1163

The Deepwater Horizon oil spill was the largest marine oil spill in US waters to date and one of the largest worldwide. Impacts of this spill on salt marsh vegetation have been well documented, although impacts on marsh macroinvertebrates have received less attention. To examine impacts of the oil spill on an important marsh invertebrate and ecosystem engineer, we conducted a meta-analysis on fiddler crabs (Uca spp.) using published sources and newly available Natural Resources Damage Assessment (NRDA) and Gulf of Mexico Research Initiative (GoMRI) data. Fiddler crabs influence marsh ecosystem structure and function through their burrowing and feeding activities and are key prey for a number of marsh and estuarine predators. We tested the hypothesis that the spill affected fiddler crab burrow density (crab abundance), burrow diameter (crab size), and crab species composition. Averaged across multiple studies, sites, and years, our synthesis revealed a negative effect of oiling on all three metrics. Burrow densities were reduced by 39 % in oiled sites, with impacts and incomplete recovery observed over 2010–2014. Burrow diameters were reduced from 2010 to 2011, but appeared to have recovered by 2012. Fiddler crab species composition was altered through at least 2013 and only returned to reference conditions where marsh vegetation recovered, via restoration planting in one case. Given the spatial and temporal extent of data analyzed, this synthesis provides compelling evidence that the Deepwater Horizon spill suppressed populations of fiddler crabs in oiled marshes, likely affecting other ecosystem attributes, including marsh productivity, marsh soil characteristics, and associated predators.  相似文献   

Cosmochemical and spectroscopic properties of Northwest Africa 7325—A consortium study          下载免费PDF全文

I. Weber  A. Morlok  A. Bischoff  H. Hiesinger  D. Ward  K. H. Joy  S. A. Crowther  N. D. Jastrzebski  J. D. Gilmour  P. L. Clay  R. A. Wogelius  R. C. Greenwood  I. A. Franchi  C. Münker 《Meteoritics & planetary science》2016,51(1):3-30

This work is part of a project to build an infrared database in order to link IR data of planetary materials (and therefore possible Mercury material) with remote sensing observations of Mercury, which will probably be obtained by the MERTIS instrument on the forthcoming BepiColombo mission. The unique achondrite Northwest Africa (NWA) 7325, which has previously been suggested to represent the first sample from Mercury, was investigated by optical and electron microscopy, and infrared and Raman spectroscopy. In addition, the oxygen, strontium, xenon, and argon isotopes were measured and the abundance of selected trace elements determined. The meteorite is a cumulate rock with subchondritic abundances of HFSE and REE and elevated Sr contents, which underwent a second heating and partial remelting process. Oxygen isotope measurements show that NWA 7325 plots in the ureilite field, close to the ALM‐A trachyandesitic fragment found in the unique Almahata Sitta meteorite breccia. On the other hand, mineralogical investigations of the pyroxenes in NWA 7325 provide evidence for similarities to the lodranites and acapulcoites. Furthermore, the rock is weakly shocked and argon isotope data record ancient (~4.5 Ga) plateau ages that have not been reset. The sample records a cosmogenic exposure age of ~19 Ma. Systematics of Rb‐Sr indicate an extreme early volatile depletion of the precursor material, similar to many other achondrite groups. However, despite its compositional similarities to other meteorite groups, our results suggest that this meteorite is unique and unrelated to any other known achondrite group. An origin for NWA 7325 as a sample from the planet Mercury is not supported by the results of our investigation. In particular, the evidence from infrared spectroscopy indicates that a direct relationship between NWA 7325 and the planet Mercury can be ruled out: no acceptable spectral match between laboratory analyses and remote sensing observations from Mercury has been obtained. However, we demonstrate that infrared spectroscopy is a rapid and nondestructive method to characterize mineral phases and thus an excellent tool for planetary surface characterization in space missions.  相似文献   

Geological controls on submarine groundwater discharge in Long Bay,South Carolina (USA)     

Richard Viso  Clay McCoy  Paul Gayes  Dimitri Quafisi 《Continental Shelf Research》2010,30(3-4):335-341

A combination of geophysical methods including continuous electrical resistivity and high-resolution Chirp sub-bottom profiling were utilized to characterize geologic controls on pore fluid salinity in the nearshore of Long Bay, SC. Resistivity values ranged from less than 1 Ω m to greater than 40 Ω m throughout the bay. Areas of elevated electrical resistivity suggest the influence of relatively fresher water on pore water composition. Geophysical evidence alone does not eliminate all ambiguity associated with lithological and porosity variations that may also contribute to electrical structure of shallow marine sediments. The anomalous field is of sufficient magnitude that lithological variation alone does not control the spatial distribution of elevated electrical resistivity zones. Geographical distribution of electrical anomalies and structures interpreted from nearby sub-bottom profiles indicates abrupt changes in shallow geologic units control preferential pathways for discharge of fresh water into the marine environment. Shore parallel resistivity profiles show dramatic decreases in magnitude with increasing distance from shore, suggesting a significant portion of the terrestrially driven fresh SGD in Long Bay is occurring via the surficial aquifer within a few hundred meters of shore.  相似文献   

Evidence for the detection of gamma-rays up to 150 TeV from the active galaxy centaurus A     

R. W. Clay  B. R. Dawson  R. Meyhandan 《Astroparticle Physics》1994,2(4):347-352

Evidence is presented for the observation of UHE gamma-rays from the direction of the active galaxy Centaurus A (NGC 5128). An excess of events from this direction is detected only for energies below the expected cosmic microwave background induced cut-off at around 150 TeV.  相似文献   

Searches for very high energy gamma rays from blazars with CANGAROO-III telescope in 2005-2009     

Y. Mizumura  J. Kushida  K. Nishijima  G.V. BicknellR.W. Clay  P.G. EdwardsS. Gunji  S. HaraS. Hayashi  S. KabukiF. Kajino  A. KawachiT. Kifune  R. KiuchiK. Kodani  Y. MatsubaraT. Mizukami  Y. MizumotoM. Mori  H. MuraishiT. Naito  M. OhishiV. Stamatescu  D.L. SwabyT. Tanimori  G. ThorntonF. Tokanai  T. ToyamaS. Yanagita  T. YoshidaT. Yoshikoshi 《Astroparticle Physics》2012,35(9):563-572

We have searched for very high energy (VHE) gamma rays from four blazars using the CANGAROO-III imaging atmospheric Cherenkov telescope. We report the results of the observations of H 2356-309, PKS 2155-304, PKS 0537-441, and 3C 279, performed from 2005 to 2009, applying a new analysis to suppress the effects of the position dependence of Cherenkov images in the field of view. No significant VHE gamma ray emission was detected from any of the four blazars. The GeV gamma-ray spectra of these objects were obtained by analyzing Fermi/LAT archival data. Wide range (radio to VHE gamma-ray bands) spectral energy distributions (SEDs) including CANGAROO-III upper limits, GeV gamma-ray spectra, and archival data, even though they are non-simultaneous, are discussed using a one-zone synchrotron self-Compton (SSC) model in combination with a external Compton (EC) radiation. The HBLs (H 2356-309 and PKS 2155-304) can be explained by a simple SSC model, and PKS 0537-441 and 3C 279 are well modeled by a combination of SSC and EC model. We find a consistency with the blazar sequence in terms of strength of magnetic field and component size.  相似文献   

Ecosystem Services in a Transitional Forest Landscape: Shifting Trajectories in Southeast Michigan,USA     

Nathan Clay  Kayla Yurco  Arun Agrawal  Lauren Persha 《社会与自然资源》2018,31(4):457-472

North American forests provide multiple ecosystem services, such as carbon storage, biodiversity, and recreation. These services are often coordinated through multifunctional management, whereby various users and owners contribute to collective agendas. Forests in exurban “transition” zones are crucial components in the sustainability of broader metropolitan landscapes, but represent a particularly understudied confluence of ecosystem services and multifunctional management. In this paper, we develop a place-based approach to assess ecosystem services in transitional forests (those between rural and urban). We demonstrate how trajectories of forest composition are linked with shifting ecosystem services that both shape and are shaped by management activities. Sited in Stinchfield Woods, a forest in southeast Michigan, this study draws on a household survey, interviews, ecological data, and archival information. Given variations in priorities over time and among different users, we suggest that coordinated, adaptive management may improve provisioning of ecosystem services in ways that benefit multiple users.  相似文献   

Critical literacy and the geography classroom: Including gender and feminist perspectives     

Lee Thompson  Tony Clay 《New Zealand geographer》2008,64(3):228-233

Abstract: Teaching secondary school geography students about different perspectives on the way knowledge is produced can be challenging. The forms of critical thinking that are prompted by interrogating the ways in which knowledge are produced equips students with intellectual tools for independent learning; an attribute which is a key feature of successful learners. This article provides an overview of the ways in which gender/feminist perspectives have been generated over time; how the teaching of these perspectives has been included in one New Zealand school, as well as suggesting useful resources.  相似文献   

Compositional changes in soil water and runoff water following managed burning on a UK upland blanket bog     

Gareth D. Clay  Fred Worrall  Evan D.G. Fraser 《Journal of Hydrology》2010,380(1-2):135-145

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Microcosms for Aquifer Research: Application to Colonization of Various Sized Particles by Ground-Water Microorganisms   总被引：1，自引：0，他引：1  

Walter K. Dodds  Clay A. Randel  Christopher C. Edler 《Ground water》1996,34(4):756-759

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