Articles by admin

Hydrocarbons in the marine environment

first_imgThe concentrations and distributions of alkanes have been determined in samples of sediment, fish, benthos and a land plant mixture from King Edward Cove, South Georgia. The fish muscle and water samples exhibited the relatively smooth envelope typical of this type of material whereas the plants, benthos, fish liver and sediments had a strong odd carbon predominance. No trace of fuel oil from previous spills or leaking storage tanks could be found in any of the samples examined although possible evidence of wastes from the whaling station were found in the deepest sediment layers in the centre of the Cove.last_img

Egg formation and the pre-laying period of Black-browed and Grey-headed Albatrosses Diomedea melanophris and D. chrysostoma at Bird Island, South Georgia

first_imgEgg composition and factors influencing egg formation were studied in Black‐browed and Grey‐headed Albatrosses Diomedea melanophris and D. chrysostoma at Bird Island, South Georgia. At nests where eggs were laid, females arrived 6–7 days after males, stayed one day during which 96% of observed copulations occurred, then departed to sea for c. 16 days in D. chrysostoma, c. 10 days in D. melanophris, returning c. two days before laying. Yolk deposition, however, lasted 21 and 20 days, and started 32 and 29 days before laying, in D. chrysostoma and D. melanophris respectively. Therefore, it is probably initiated by environmental factors not by copulation. Egg, albumen and yolk mass are significantly greater in D. chrysostoma but the proportionate composition of the species’ eggs is nearly identical. Reduced differences in chick mass at hatching may reflect the longer incubation period in D. chrysostoma or relate to subsequent differences in chick growth rate.last_img read more

Fish and squid in the diet of king penguin chicks, Aptenodytes patagonicus, during winter at sub-antarctic Crozet Islands

first_imgThe diet of king penguins, Aptenodytes patagonicus, rearing chicks was studied during three consecutive austral winters (1990, 1991 and 1992) at Crozet Islands. The mean stomach content mass of the 47 samples was 503 g. Percentages of wet and reconstituted masses showed that both fishes (66 and 36%, respectively) and squid (34 and 64%) are important components of the winter diet. Juveniles of the demersal onychoteuthid squid Moroteuthis ingens form the bulk of the cephalopod diet, and this was the main prey by reconstituted mass (57%). Myctophid fish (lantern-fishes) accounted for most of the fish diet, constituting together 32% by mass. The three main species of myctophids eaten in summer by king penguins were either very rare in winter (Electrona carlsbergi) or accounted for a smaller proportion of the diet (Krefftichthys anderssoni = 1.5% by mass and Protomyctophum tenisoni = 4.6%). Five other myctophids, which are rarely consumed in summer, contributed 24% of the diet by mass in winter (Gymnoscopelus piabilis = 18.1%, Lampichthys procerus = 2.4%, G. nicholsi = 1.3%, and Metelectrona ventralis and Electrona subaspera = 1.0%). The greater diversity of prey in winter suggests a more opportunistic feeding behaviour at a time probably marked by a change in prey availability. Both the known ecology of the fish and squid prey and the barely digested state of some items suggest that in winter breeding adults forage in the outer shelf, upper slope and oceanic areas in the close vicinity of the Crozet Islands to feed their chicks. Finally, using king penguins as biological samplers, the present work provides novel data on the previously unstudied mesopelagic/epibenthic marine community in waters surrounding the Crozet Islands. Seventeen myctophid fish have been identified to species level. These include several poorly known species in the southern Indian Ocean. The occurrence of small, nearly intact, cephalopods in the diet of king penguins suggests that spawning grounds of four squid species may be located near the Crozet Archipelago.last_img read more

Evidence for shallowing and uplift from bathymetric records of Deception Island, Antarctica

first_imgDeception Island is a large volcanic centre in Bransfield Strait, a very young marginal basin between the South Shetland Islands and Antarctic Peninsula. It has a historical record of volcanic activity, with the most recent eruption occurring in 1970. The island is a stratovolcano with a large flooded caldera forming a natural harbour known as Port Foster. It has been a focus of human activity since early last century, as a base for whaling and sealing expeditions and the locus of several scientific stations. During that period, many bathymetric surveys were carried out, the earliest in 1829 and the most recent in 1993. This study concentrates on surveys from 1948 onwards. Because Port Foster can be classified as a restless caldera, the bathymetric records were analysed for evidence of volcano-tectonic deformation, particularly caldera resurgence (uplift) which could have significant consequences for hazard and risk assessments of the volcano. The results show that a distinctive pattern of shallowing and uplift is present, correlating well with known and inferred volcanic and volcanotectonic processes on the island. In particular, bathymetric records between 1949 and 1993 show uplift rates as high as 0.3–0.5 m a−1, far exceeding normal sedimentation rates in a caldera this size. Rapid uplift in an arcuate offshore area not affected by the sedimentation of recent eruptions suggests that volcano tectonic resurgence or tectono-magmatic effects of an upward migrating magma chamber present a significant risk to the considerable human activity taking place in the region.last_img read more

Wintertime controls on summer stratification and productivity at the western Antarctic Peninsula

first_imgWe report results collected year-round since 1998 in northern Marguerite Bay, just inside the Antarctic Circle. The magnitude of the spring phytoplankton bloom is much reduced following winters with reduced sea-ice cover. In years with little winter sea-ice the exposed sea surface leads to deep mixed layers in winter, and reduced water-column stratification the following spring. Summer mixed-layer depths are similar, however, so the change is not in overall light availability but toward a less stable water column with greater vertical mixing and increased variability in the light conditions experienced by phytoplankton. Macronutrient concentrations are replete at all times, but the increased vertical mixing likely reduces iron availability. The timing of bloom initiation is similar between heavy and light ice years, occurring soon after light returns in early spring, at a mixed-layer averaged light level of < 1 mol photon m−2 d−1. Ongoing regional climate change in the WAP area, and notably the ongoing loss of winter sea-ice, is likely to drive a downward trend in the magnitude of phytoplankton blooms in this region of the Antarctic Peninsula.last_img read more

Mercury concentrations in primary feathers reflect pollutant exposure in discrete non-breeding grounds used by Short-tailed Shearwaters

first_imgWe measured mercury concentrations ([Hg]) and nitrogen stable isotope ratios (δ15N) in the primary feathers of Short-tailed Shearwaters (Puffinus tenuirostris) that were tracked year-round. The [Hg] were highest in 14 birds that used the Okhotsk and northern Japan Seas during the non-breeding period (2.5 ± 1.4 μg/g), lowest in nine birds that used the eastern Bering Sea (0.8 ± 0.2 μg/g), and intermediate in five birds that used both regions (1.0 ± 0.5 μg/g), with no effects of δ15N. The results illustrate that samples from seabirds can provide a useful means of monitoring pollution at a large spatial scale.last_img

A strong wind event on the Ross Ice Shelf, Antarctica: A case study of scale interactions

first_imgIn situ observations, satellite imagery, numerical weather prediction, and reanalysis fields are used to investigate the synoptic and mesoscale environment of a strong wind event (SWE) at McMurdo Station/Ross Island region on the Ross Ice Shelf, Antarctica, on 10 October 2003. The SWE occurred during the passage of a sequence of three mesoscale low pressure systems from the central Ross Ice Shelf to the southwest Ross Sea. A potential vorticity (PV) analysis showed that the lows drew air of continental origin down the glacial valleys of the Transantarctic Mountains and onto the ice shelf as a katabatic drainage flow. However, the analysis indicated that the air mass associated with the SWE was of recurved maritime origin drawn in by the second mesoscale low (L2). This air mass approached McMurdo Station from the south where interactions with the orography played a critical role. In the early stages of the event, when the wind speed was less than 10 m s−1, the air was deflected around the topographical features, such as Minna Bluff and Black and White Islands. As the pressure gradient increased, winds of more than 10 m s−1 crossed the orography and developed mountain waves along the lee slopes. When the Froude number became larger than 1, large-amplitude vertically propagating mountain waves developed over the McMurdo Station/Ross Island area, increasing the wind to 16 m s−1. The reanalysis fields did not resolve the mesoscale lows; however, the Antarctic Mesoscale Prediction System (AMPS) model was able to simulate important characteristics of the SWE such as the mesoscale low pressure system, flow around the topographical barrier, and the mountain wave.last_img read more

CMIP6/PMIP4 simulations of the mid-Holocene and Last Interglacial using HadGEM3: comparison to the pre-industrial era, previous model versions and proxy data

first_imgPalaeoclimate model simulations are an important tool to improve our understanding of the mechanisms of climate change. These simulations also provide tests of the ability of models to simulate climates very different to today. Here we present the results from two brand-new simulations using the latest version of the UK’s physical climate model, HadGEM3-GC3.1; they are the mid-Holocene (∼6 ka) and Last Interglacial (∼127 ka) simulations, both conducted under the auspices of CMIP6/PMIP4. This is the first time this version of the UK model has been used to conduct palaeoclimate simulations. These periods are of particular interest to PMIP4 because they represent the two most recent warm periods in Earth history, where atmospheric concentration of greenhouse gases and continental configuration are similar to the pre-industrial period but where there were significant changes to the Earth’s orbital configuration, resulting in a very different seasonal cycle of radiative forcing. Results for these simulations are assessed firstly against the same model’s pre-industrial control simulation (a simulation comparison, to describe and understand the differences between the pre-industrial – PI – and the two palaeo simulations) and secondly against previous versions of the same model relative to newly available proxy data (a model–data comparison, to compare all available simulations from the same model with proxy data to assess any improvements due to model advances). The introduction of this newly available proxy data adds further novelty to this study. Globally, for metrics such as 1.5 m temperature and surface rainfall, whilst both the recent palaeoclimate simulations are mostly capturing the expected sign and, in some places, magnitude of change relative to the pre-industrial, this is geographically and seasonally dependent. Compared to newly available proxy data (including sea surface temperature – SST – and rainfall) and also incorporating data from previous versions of the model shows that the relative accuracy of the simulations appears to vary according to metric, proxy reconstruction used for comparison and geographical location. In some instances, such as mean rainfall in the mid-Holocene, there is a clear and linear improvement, relative to proxy data, from the oldest to the newest generation of the model. When zooming into northern Africa, a region known to be problematic for models in terms of rainfall enhancement, the behaviour of the West African monsoon in both recent palaeoclimate simulations is consistent with current understanding, suggesting a wetter monsoon during the mid-Holocene and (more so) the Last Interglacial, relative to the pre-industrial era. However, regarding the well-documented “Saharan greening” during the mid-Holocene, results here suggest that the most recent version of the UK’s physical model is still unable to reproduce the increases suggested by proxy data, consistent with all other previous models to date.last_img read more

BYU’s Bryant and Collinsworth To Compete in NBA Summer League

first_img Written by FacebookTwitterLinkedInEmailLAS VEGAS-Former BYU men’s basketball players Elijah Bryant and Kyle Collinsworth will be competing in the NBA Summer League in Las Vegas, giving themselves a chance to showcase their skills for their respective teams.Bryant, a first-team All-West Coast conference honoree in 2017-18, led the Cougars with 18.2 points a game, while also contributing 6.3 rebounds and 2.3 assists.Bryant will be playing on the Philadelphia 76ers’ summer league squad while Collinsworth returns to the Dallas Mavericks’ summer league roster.Last season, Collinsworth played in 32 games for Dallas last season, posting 3.2 points, 3.3 rebounds and 1.8 assists per game.Both the Mavericks and 76ers will play three games in Las Vegas and will then be seeded into a single-elimination tournament. July 6, 2018 /Sports News – Local BYU’s Bryant and Collinsworth To Compete in NBA Summer League Brad James Tags: BYU Men’s Basketball/Dallas Mavericks/Elijah Bryant/Kyle Collinsworth/NBA Summer League/Philadelphia 76erslast_img read more

Scoreboard roundup — 2/1/19

first_imgFebruary 2, 2019 /Sports News – National Scoreboard roundup — 2/1/19 Written by FacebookTwitterLinkedInEmailiStock(NEW YORK) — Here are the scores from Friday’s sports events:NATIONAL BASKETBALL ASSOCIATIONCharlotte 100, Memphis 92Boston 113, N.Y. Knicks 99Oklahoma City, 118 Miami 102Utah 128, Atlanta 112Denver 136, Houston 122NATIONAL HOCKEY LEAGUEWashington 4, Calgary 3Tampa Bay 1, N.Y. Islanders 0Pittsburgh 5, Ottawa 3Chicago 7, Buffalo 3Nashville 4, Florida 1Carolina 5, Vegas 2Detroit 3, Toronto 2Dallas 3, Minnesota 1TOP 25 COLLEGE BASKETBALLIowa 74, (5) Michigan 59Bowling Green 92, (18) Buffalo 88(24) Wisconsin 69, (21) Maryland 61Copyright © 2019, ABC Radio. All rights reserved.center_img Beau Lundlast_img