May 9, 2021
  • 6:00 am The pattern of growth and translocation of photosynthate in a tundra moss, Polytrichum alpinum
  • 5:59 am Aspects of the biology of Antarctomysis maxima (Crustacea: Mysidacea)
  • 5:58 am Belemnite battlefields
  • 5:54 am Middle Jurassic air fall tuff in the sedimentary Latady Formation, eastern Ellsworth Land
  • 5:53 am Concentration, molecular weight distribution and neutral sugar composition of DOC in maritime Antarctic lakes of differing trophic status

first_imgGreen aboveground shoots of the moss Polytrichum alpinum Hedw., growing on the tundra at Point Barrow, Alaska, were exposed to 14CO2 in the field. Autoradiography and subsequent counting revealed preferential translocation of the labeled compounds into new belowground shoots arising from the extensive underground stem system. Within 24 h all stem systems extracted had been labeled throughout, a maximum distance of 7.5 cm being covered in this time, indicating minimum rates of 3.1 mm h−1.Increases in the number of new shoots aboveground throughout the season revealed the extent and importance of this translocation. Innate markers of seasonal growth enabled ages of the shoots at two sites to be determined and also the ages of shoots at production of gametangia in a third site where fruiting was common. The relative photosynthetic rates of the successive seasons’ growth were also determined, and showed that by the 3rd year the photosynthetic capacity had dropped to about 40% of that in the youngest tissue on the same shoot.The patterns of growth and translocation of photosynthate in Polytrichum alpinum are discussed in relation to survival on the tunda.last_img read more

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Population structure and aspects of the reproductive biology of Antarctomysis maxima from South Georgia and the South Orkney Islands were examined. Size frequency analysis indicated that the generation time is two years at South Georgia, but may approach four years at the South Orkneys. Egg production is greater for a given size of female at South Georgia but by virtue of a larger egg, brood production in terms of ash-free dry weight is slightly greater at the South Orkneys. Young are brooded over winter at both sites and are released in spring. Females are clearly capable of breeding twice at South Georgia and it is suggested that this is also the case at the South Orkneys. These results are discussed in relation to other studies on cold water mysids and to environmental adaptations exhibited by other Antarctic marine invertebrates. read more

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first_imgMass accumulations of belemnite rostra (‘belemnite battlefields’) are common in Mesozoic sediments, and accumulations of belemnoids are also known from older rocks. Many Recent teuthid species suffer mortality immediately after spawning, and some authors have suggested that belemnite accumulations record a similar phenomenon. Conversely, it is clear that many belemnite battlefields actually formed in an environment of net sediment loss, with current alignment and winnowing. A proposed model for the production of belemnite battlefields involves five possible pathways: post-spawning mortality, catastrophic mass mortality, predation concentration, stratigraphical condensation, and resedimentation. Although accumulations that have not been reworked are rare, it is possible to recognise the generating agents of belemnite accumulations through their intrinsic features. A genetic classification of belemnite battlefields, based on the identified pathways, is tested through field examples in Britain and Antarctica, as well as through published exampleslast_img read more

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first_imgRhyolitic volcanism along the proto-Pacific margin of Gondwana occurred at intervals throughout the Jurassic. Silicic melt generation has been interpreted as a result of interaction between mantle plumes and subduction modified lower crust. The rhyolitic Mount Poster Formation of the southern Antarctic Peninsula is c. 184 Ma in age (VI), whereas silicic volcanism of the northern Antarctic Peninsula is c. 168 Ma (V2). A thin, (13.5 cm) reworked air fall tuff, interbedded with sandstone and mudstone of the Latady Formation in the southern Antarctic Peninsula has a REE pattern similar to V2 volcanic material but is isotopically similar to the extracaldera, low-Ti rhyolites of the VI Mount Poster Formation. The tuff is interbedded with lithofacies that have been assigned a Callovian age (164-159 Ma) in the west of the area. Simple mixing between a MASH source and reworked Early Jurassic (184 Ma) V I volcanic material during V2 volcanism in the area explains the apparent discrepancy between the faunal age and the isotopic characteristics of the ash fall. This supports a Middle Jurassic (168 Ma) age that also corresponds to a 167 3 Ma age from Mt Rex on the periphery of the Mount Poster Formation, which was previously thought to be anomalous.last_img read more

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first_imgThe molecular weight distributions and hydrolysable neutral sugar composition of dissolved organic carbon (DOC) was investigated in four maritime Antarctic lakes on Signy Island of different trophic status; Heywood Lake (eutrophic), Light Lake (oligo-mesotrophic), Sombre Lake and Moss Lake (both oligotrophic). Tangential flow ultra-filtration (TFU) was used to separate DOC into high molecular weight (HMW; >1000 Da) and low molecular weight (LMW; < 1000 Da) size fractions. Pulsed amperometric detection-high performance liquid chromatography (PAD-HPLC) was used to determine the hydrolysable neutral sugar molecular composition of each size fraction. Total DOC concentrations defined the trophic trend in the four lakes and ranged from 8 to 303 μM. The 1000 Da total organic carbon and had extremely high concentrations of total hydrolysable neutral sugars (11 μM) corresponding to 43% of total DOC. However, no clear pattern was apparent with regard to lake trophic status and potential sources of DOC, and the measured variations in individual aldose concentration, composition and their various molecular weight fractions.last_img read more

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first_imgAn isopycnic coordinate ocean circulation model is applied to the ocean cavity beneath Filchner-Ronne Ice Shelf, investigating the role of tides on sub-ice shelf circulation and ice shelf basal mass balance. Including tidal forcing causes a significant intensification in the sub-ice shelf circulation, with an increase in melting (3-fold) and refreezing (6-fold); the net melt rate and seawater flux through the cavity approximately doubles. With tidal forcing, the spatial pattern and magnitude of basal melting and freezing generally match observations. The 0.22 m a(-1) net melt rate is close to satellite-derived estimates and at the lower end of oceanographic values. The Ice Shelf Water outflow mixes with shelf waters, forming a cold (<-1.9 degrees C), dense overflow (0.83 Sv) that spills down the continental slope. These results demonstrate that tidal forcing is fundamental to both ice shelf-ocean interactions and deep-water formation in the southern Weddell Sea. Citation: Makinson, K., P. R. Holland, A. Jenkins, K. W. Nicholls, and D. M. Holland (2011), Influence of tides on melting and freezing beneath Filchner-Ronne Ice Shelf, Antarctica, Geophys. Res. Lett., 38, L06601, doi: 10.1029/2010GL046462.last_img read more

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first_imgTracking technology has revolutionized knowledge of seabird movements; yet, few studies have examined sex differences in distribution and behavior of small to medium-sized, sexually-monomorphic seabirds. Application of bird-borne geolocation-immersion loggers revealed seasonal segregation in the sexually-monomorphic Sooty Shearwater Puffinus griseus, mainly in the pre-laying period, when there were clear differences in reproductive roles. Shearwaters first returned to the Falkland Islands on 27 Sept±8 d; males, on average, 8 d earlier than females. Prior to egg-laying, distribution at sea, colony attendance and behaviour depended on sex. Males foraged locally over the southern Patagonian Shelf and Burdwood Bank, spending mainly single days at sea and intervening nights in the burrow. Females, who flew for more of the day during this time, foraged in more distant areas of the northern Patagonian Shelf and Argentine Basin that were deeper, warmer and relatively more productive. Attendance of females at the colony was also more variable than that of males and, overall, males were present for significantly more of the pre-laying period (38 vs. 19% of time). Sex differences were reduced following egg-laying, with males and females using similar foraging areas and making trips of similar mean duration in incubation (7.6±2.7 d) and chick-rearing (1.4±1.3 d). Congruence continued into the non-breeding period, with both sexes showing similar patterns of activity and areas of occupancy in the NW Atlantic. Thus, seasonal changes in reproductive roles influenced patterns of sexual segregation; this occurred only early in the season, when male Sooty Shearwaters foraged locally, returning regularly to the colony to defend (or maintain) the burrow or the mate, while females concentrated on building resources for egg development in distant and relatively more productive waters.last_img read more

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first_imgThe structure, variability, and mean-flow interactions of the quasi-2-day wave (Q2DW) in the mesosphere and lower thermosphere during January 2015 were studied employing meteor and medium-frequency radar winds at eight sites from 23 degrees S to 76 degrees S and Microwave Limb Sounder (MLS) temperature and geopotential height measurements from 30 degrees S to 80 degrees S. The event had a duration of 20-25 days, dominant periods of 44-52 hr, temperature amplitudes as large as 16 K, and zonal and meridional wind amplitudes as high as 40 and 80 m/s, respectively, at middle and lower latitudes. MLS measurements enabled definition of balance winds that agreed well with radar wind amplitudes and phases at middle latitudes where amplitudes were large and quantification of the various Q2DW modes contributing to the full wave field. The Q2DW event was composed primarily of the westward zonal wavenumber 3 (W3) mode but also had measurable amplitudes in other westward modes W1, W2, and W4; eastward modes E1 and E2; and stationary mode S0. Of the secondary modes, W1, W2, and E2 had the larger amplitudes. Inferred MLS balance winds enabled estimates of the Eliassen-Palm fluxes for each mode, and cumulative zonal accelerations that were found to be in reasonable agreement with radar estimates from 35 degrees S to 70 degrees S at the lower altitudes at which radar winds were available.last_img read more

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first_img FacebookTwitterLinkedInEmaildomnicky/iStock(OAKLAND, Calif.) — The city of Oakland, California is suing the Raiders and the NFL over the team’s planned 2020 move to Las Vegas, calling it illegal.Last year, the Raiders announced it would be moving from Oakland after the city was outbid by Las Vegas.In a tweet Tuesday, Oakland Mayor Libby Schaaf said the “NFL’s Billionaires Boys Club ditched Oakland out of sheer greed and left taxpayers with millions in unpaid stadium debt.”The NFL’s Billionaires Boys Club ditched Oakland out of sheer greed and left taxpayers with millions in unpaid stadium debt. Our community’s support and loyalty were met with nothing but bad faith. Today we’re standing up for residents, taxpayers and fans. https://t.co/7nxcbXAsln— Libby Schaaf (@LibbySchaaf) December 11, 2018The city of Oakland went on to call the NFL a “cartel” in a press release announcing the lawsuit.For more on the lawsuit, watch the report from ABC News’ T. J. Holmes in the video below:Copyright © 2018, ABC Radio. All rights reserved. December 12, 2018 /Sports News – National Oakland sues Raiders, NFL over team’s planned move Written bycenter_img Beau Lundlast_img read more

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first_img FacebookTwitterLinkedInEmailiStock(NEW YORK) — Here are the scores from Wednesday’s sports events:NATIONAL BASKETBALL ASSOCIATIONOT Detroit 120, Orlando 115Milwaukee 111, Memphis 101Boston 117, Toronto 108OT Brooklyn 145, Houston 142San Antonio 105, Dallas 101Portland 129, Cleveland 112Golden State 147, New Orleans 140Utah 129, L.A. Clippers 109NATIONAL HOCKEY LEAGUEOttawa 5, Colorado 2Philadelphia 4, Boston 3OT Buffalo 4, Calgary 3SO Edmonton 3, Vancouver 2Arizona 6, San Jose 3TOP-25 COLLEGE BASKETBALLIowa St. 68, (8) Texas Tech 64(14) Auburn 85, Texas A&M 66Kansas St. 74, (20) Oklahoma 61(21) Houston 69, SMU 58(23) Iowa 89, Penn St. 82Copyright © 2019, ABC Radio. All rights reserved. Written by Beau Lundcenter_img January 17, 2019 /Sports News – National Scoreboard roundup — 1/16/19last_img read more

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