Short-term temporal dynamics of algal species in a subtidal kelp bed in relation to changes in environmental conditions and canopy biomass   总被引：1，自引：0，他引：1  

Thomas Wernberg  Nisse Goldberg 《Estuarine, Coastal and Shelf Science》2008

Understanding temporal variation at the scale of weeks to months is critical to understanding broad temporal patterns in diversity in the same way as understanding diversity across landscapes relies on understanding variation at the scale of meters. However, whereas small-scale spatial variation in temperate reef algal assemblages has been extensively studied, fine-scale temporal changes have not been well addressed. By sampling the macroalgae of a subtidal reef near Perth (Australia), dominated by the small kelp Ecklonia radiata, every ∼40 days over a 2-year period, we were able to test whether temporal changes in species richness, assemblage structure and species turn-over were related to seasonal changes in surface temperature, solar radiation and wave height. A total of 93 macroalgal taxa were identified, and species richness per sampling time ranged from 25 to 64 taxa 1.25 m⁻². Biomass of E. radiata was positively correlated with changes in sea surface temperature and light, and negatively correlated with wave height. Species richness, assemblage structure and turn-over of other macroalgae were more associated with seasonal changes in kelp biomass than environmental variables per se. We conclude that seasonal changes in environmental conditions drive changes in the kelp canopy, which in turn drive changes in species richness and assemblage structure. This suggests that habitat-formers such as kelps can exert a strong temporal influence on associated communities, analogous to well-described spatial influences. Thus, as kelp canopy biomass expands and retracts over time-scales of weeks to months, so does available space for colonization and growth, resulting in a high species turn-over. Species richness is therefore increased and maintained through time, in the same way as canopy-gap mosaics increase and maintain species richness across spatial landscapes.  相似文献   

Variations in New York city’s urban heat island strength over time and space   总被引：3，自引：1，他引：2  

S. R. Gaffin  C. Rosenzweig  R. Khanbilvardi  L. Parshall  S. Mahani  H. Glickman  R. Goldberg  R. Blake  R. B. Slosberg  D. Hillel 《Theoretical and Applied Climatology》2008,94(1-2):1-11

  相似文献   

Occupation surfaces sealed by the Avellino eruption of Vesuvius at the Early Bronze Age village of Afragola in southern Italy: A micromorphological analysis     

Tiziana Matarazzo  Francesco Berna  Paul Goldberg 《Geoarchaeology》2010,25(4):437-466

This paper reconstructs the use of space and defines activity areas within a single hut (Hut 8) at the Early Bronze Age village of Afragola (southern Italy). The village, consisting of a number of huts and other structures, was covered by approximately 1m of volcanic ash during the eruption of Vesuvius in 3550 ± 20BP. Thirteen samples were collected from inside the hut to analyze the spatial variability in sedimentary characteristics among three areas of Hut 8—the apsidal, central, and entrance areas. The micromorphological analysis revealed details about the occupation surface and its relationship to features and material remains in the hut not apparent in the field. The apsidal area was probably used for storage but not of solids, as no significant quantities of organic material were found. The central area contains a small oven, calcareous ash from fires, and organic material composed of charred remains and bone fragments and was likely used for small‐scale household tasks. A possible connection exists between the lithics and the microstratigraphic sequencing in the area west of the oven, suggesting that people congregated there to perform specific tasks. The entrance area contains highly compacted and heterogeneous sediments that were brought in from outside. Notable is the paucity of anthropogenic materials found inside the hut, especially given the remarkable preservation offered by the thick cover of volcanic ash. We hypothesize that Hut 8 was not occupied long enough to produce a large amount of debris or that it had limited indoor activities and was thoroughly cleaned. © 2010 Wiley Periodicals, Inc.  相似文献   

Analytical Constraints on the Measurement of the Sulfur Isotopic Composition and Concentration of Trace Sulfate in Phosphorites: Implications for Sulfur Isotope Studies of Carbonate and Phosphate Rocks     

Tatiana Goldberg  Graham A. Shields  Robert J. Newton 《Geostandards and Geoanalytical Research》2011,35(2):161-174

The aim of this study was to evaluate the existing methods for extracting trace sulfate from francolite and measuring its concentration and sulfur isotope composition. Phosphatic rocks were chemically and thermally treated to remove non‐structural SO₄^2? in francolite, which would otherwise be inadvertently included in geochemical analyses of the structurally‐bound sulfate. Acetic acid (10% v/v) proved to be effective in removing calcite, dolomite and ankerite without affecting francolite. To remove all ‘easily’ soluble sulfates, such as Ca‐sulfates and adsorbed sulfate, rinsing with 10% v/v NaCl had to be repeated several times for most samples. For subsequent S isotope determination sample combustion at 600 °C was found to be an efficient way to remove non‐francolite S‐bearing phases. From a number of SO₄^2? detection methods tested, ICP‐AES proved to be the most accurate. For francolite‐sulfate recovery, our recommended protocol involved repeated rinsing of powdered phosphorites with 10% NaCl as well as NaOCl, and testing of the filtrate for SO₄^2? in each wash. If only S isotope compositions are needed, combustion at 600 °C with a subsequent de‐ionised water rinse could be undertaken instead of repeated NaOCl rinsing for studies of both francolite and carbonate. Re‐analysis of previously published data, using the new protocol, provided evidence that the use of this protocol considerably improves data quality.  相似文献   

Proposal for an International Molybdenum Isotope Measurement Standard and Data Representation     

Thomas F. Nägler  Ariel D. Anbar  Corey Archer  Tatiana Goldberg  Gwyneth W. Gordon  Nicolas D. Greber  Christopher Siebert  Yoshiki Sohrin  Derek Vance 《Geostandards and Geoanalytical Research》2014,38(2):149-151

Molybdenum isotopes are increasingly widely applied in Earth Sciences. They are primarily used to investigate the oxygenation of Earth's ocean and atmosphere. However, more and more fields of application are being developed, such as magmatic and hydrothermal processes, planetary sciences or the tracking of environmental pollution. Here, we present a proposal for a unifying presentation of Mo isotope ratios in the studies of mass‐dependent isotope fractionation. We suggest that the δ^98/95Mo of the NIST SRM 3134 be defined as +0.25‰. The rationale is that the vast majority of published data are presented relative to reference materials that are similar, but not identical, and that are all slightly lighter than NIST SRM 3134. Our proposed data presentation allows a direct first‐order comparison of almost all old data with future work while referring to an international measurement standard. In particular, canonical δ^98/95Mo values such as +2.3‰ for seawater and ?0.7‰ for marine Fe–Mn precipitates can be kept for discussion. As recent publications show that the ocean molybdenum isotope signature is homogeneous, the IAPSO ocean water standard or any other open ocean water sample is suggested as a secondary measurement standard, with a defined δ^98/95Mo value of +2.34 ± 0.10‰ (2s).  相似文献   

Source localization in shallow water in the presence of sensorlocation uncertainty     

Jakoby  A. Goldberg  J. Messer  H. 《Oceanic Engineering, IEEE Journal of》2000,25(3):331-336

The problem of source localization in shallow water in the presence of sensor location uncertainty is considered. The Cramer-Rao Bound is used to carry out a feasibility study for the joint source and sensor location problem when the multipath propagation channel is modeled as a known, deterministic waveguide. Unlike the free-space propagation channel, the boundedness of the shallow-water waveguide along its vertical axis provides the key to joint determination of the source and sensor location parameters. It is seen that, when a set of intuitive identifiability conditions are satisfied, numerical examples indicate that, for the scenarios considered, the resulting loss in accuracy with which the source location can be estimated due to sensor location uncertainty may be tolerable  相似文献   

Temporal dynamics of dissolved combined neutral sugars and the quality of dissolved organic matter in the Northwestern Sargasso Sea     

Stuart J. Goldberg  Craig A. Carlson  Dennis A. Hansell  Norm B. Nelson  David A. Siegel 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(5):672-685

The dynamics of dissolved combined neutral sugars (DCNS) were assessed in the upper 250 m at the Bermuda Atlantic Time-series Study (BATS) site between 2001 and 2004. Our results reveal a regular annual pattern of DCNS accumulation with concentrations increasing at a rate of 0.009–0.012 μmol C L^?1 d^?1 in the surface 40 m from March to July and reaching maximum mean concentrations of 2.2–3.3 μmol C L^?1. Winter convective mixing (between January and March) annually exported surface-accumulated DCNS to the upper mesopelagic zone (100–250 m), as concentrations increased there by 0.3–0.6 μmol C L^?1. The exported DCNS was subsequently removed over a period of weeks following restratification of the water column. Vertical and temporal trends in DCNS yield (% of DOC) supported its use as a diagenetic indicator of DOM quality. Higher DCNS yields in surface waters suggested a portion of the DOM accumulated relatively recently compared to the more recalcitrant material of the upper mesopelagic that had comparably lower yields. DCNS yields and mol% neutral sugar content, together, indicated differences in the diagenetic state of the surface-accumulated and deep pools of DOM. Seasonally accumulated, recently produced DOM with higher DCNS yields was characterized by elevated mol% of galactose and mannose+xylose levels. Conversely, more recalcitrant DOM from depths >100 m had lower DCNS yields but higher mol% of glucose. Lower DCNS yields and elevated mol% glucose were also observed in the surface waters during winter convective mixing, indicating an entrainment of a diagenetically altered DOM pool into the upper 100 m. A multivariate statistical analysis confirms the use of DCNS as an index of shifts in DOM quality at this site.  相似文献   

Cadmium and the oceans     

Edward D. Goldberg 《Marine pollution bulletin》1984,15(5):163-164

  相似文献   

Venus gravity west of Beta Regio     

Z.M. Goldberg  R.D. Reasenberg 《Icarus》1985,62(1):129-142

Doppler tracking data from the Pioneer Venus Orbiter (PVO) have been used to estimate the anomalous gravity field in the region of Venus west of Beta Regio. The analysis invokes a Kalman filter-smoother to solve the nonlinear spacecraft state estimation problem and a linear Bayesian estimator to perform the geophysical inversion. The topographic map for this region, derived from the PVO radar, has been filtered to have the same distortions and degree of smoothing as the gravity map. The undulations of the gravity are about 0.2 times as large as expected from the topography on the assumption that the latter is uncompensated. A comparison of the gravity and topography by means of the spectral admittance is consistent with Airy compensation at a depth of 50 km if the surface material has a density of 2.6 g/cm³. However, this is not a unique interpretation.  相似文献   

Man and his physical environment: Gary D. McKenzie and Russell O. Utgard (Editors): Readings in Environmental Geology. Burgess Publishing Company,Minneapolis. 338 pp. Price $4.95     

Edward D Goldberg 《Geochimica et cosmochimica acta》1973,37(1):171

  相似文献