Sublittoral epifaunal communities at Signy Island, Antarctica. II. Below the ice-foot zone

May 9, 2021 0 Comments

first_imgPhotographic samples were taken every 5 m along two 40 m transects on mostly rock face at Signy Island, Antarctica, during the austral winter of 1991. Dense and taxonomically rich communities of benthos occurred at most of the sublittoral study locations. These communities, however, varied significantly with substratum type, substratum profile and depth. Algae were generally the largest occupiers of space, but the area of substratum colonised by animal taxa increased whenever the profile approached vertical. Shallower than 15 m, disturbance effects, largely from ice, restricted community development to a high degree, but the frequency of disturbance at 25 m appeared to maintain high diversity by preventing domination of the assemblage by a few competitively superior taxa. Bryozoans, and to a lesser extent sponges, were the most abundant animal phyla. Among the bryozoans, species with an encrusting growth form occurred at the shallowest depths followed by encrusting massive/folaceous species and, at 40 m, the erect flexible forms. The ratio of encrusting to erect bryozoan species changed rapidly over the 0 to 50 m depth zone, from exclusively encrusting at 0 to 5 m to approaching 1 at 50 m. The erect bryozoans studied, from the shallow sublittoral to 290 m, could be classified as encrusting massive (foliaceous), erect flexible or erect rigid forms. There was some suggestion, despite the overlap between groups and considerable intra-group variation, that encrusting massive forms were abundant in the shallowest water, followed by erect flexible forms and then erect rigid forms with increasing depth. Some species which occurred as encrusting massive/foliaceous forms in deeper water occurred mostly in encrusting form only in shallow water (<15 m).last_img read more

Passive microwave retrievals of precipitation over the Southern Ocean

May 9, 2021 0 Comments

first_imgMany algorithms have been developed to retrieve precipitation and cloud liquid water from passive microwave measurement at mid-latitudes and in the tropics, but these algorithms do not necessarily work well over the ice-free oceans that surround the Antarctic continent where most precipitation falls in the form of snow.It is known that the clouds that produce most of the precipitation over the southern latitudes are thin stratiform clouds and the precipitation they give is of slight intensity (less than 0.5mm h -1 rain equivalent). In this paper the polarization corrected temperature (PCT) method for detecting precipitation is applied and compared with a new physical method that simultaneously retrieves both cloud liquid water and precipitation amount. Both methods are compared with the few in situ measurements available. The new iterative physical method is found to give better results and does not need any empirically derived parameters.last_img read more

Strontium-isotope stratigraphy of the CRP-1 drillhole, Ross Sea, Antarctica

May 9, 2021 0 Comments

first_imgStrontium isotope stratigraphy was used to date five discrete horizons within CRP- 1. Early and late Quaternary (0 87- 1 3 Ma and 0-0 67 Ma respectively) age sedimentsoverlie a major sequence boundary at 43.15 meters below sea floor (mbsf) This hiatus is estimated to account for -16 m y of missing section. Early Miocene (16 6-20 8-25 Ma)age deposits below this boundary are in turn cut by multiple erosion surfaces representing hiatuses of between 0.2 and 1.2 m.y. Estimated minimum sedimentation rates rangebetween 0.9 and 2.8 cm/k.y. in the Quaternary, and 1.5 and 6.4 cm/k.y. in the lower Miocene.last_img read more

Aerial dispersal and survival of sewage-derived faecal coliforms in Antarctica

May 9, 2021 0 Comments

first_imgThis study demonstrates for the first time that faecalcoliform bacteria can survive airborne transfer in Antarctica, but are unlikely to survive for prolonged periods following deposition due to environmental stresses. The dispersal and survival of airborne faecalcoliform bacteria from the sewage outfall at Rothera Research Station (Adelaide Island, Antarctic Peninsula) was examined. Northerly winds created the potential for sewage aerosols to be blown the 150 m from the outfall to the research station. During moderate wind velocities (∼15 m s−1), faecalcoliform bacteria were detected up to 175 m downwind of the outfall amongst the station buildings. However, moderate doses of solar UV radiation (∼20 W m−2) were capable of reduced the number of viable wind-deposited bacteria by up to 99.9%, compared with periods of low solar UV radiation (∼1 W m−2). Further experiments showed that, within 1 h of deposition, desiccation stress and solar radiation independently reduced coliform viability by up to 99.8% and 99.98%, respectively. These results imply that airborne faecalcoliforms are unlikely to survive for prolonged periods following deposition or cause infection of local wildlife or human populations, though this may not be the case for more stress-resistant microorganisms.last_img read more

Diurnal variability of subglacial drainage conditions as revealed by tracer experiments

May 9, 2021 0 Comments

first_imgThe morphology of the drainage system of Unteraargletscher, Switzerland, and the diurnal variability of drainage conditions were investigated by conducting a series of tracer tests over a number of discharge cycles during the ablation season 2000. Dye injections into a moulin were repeated at intervals of a few hours and were accompanied by simultaneous measurements of discharge of supraglacial meltwater draining into the moulin and bulk runoff in the proglacial stream. Fast transit velocities in conjunction with low dispersion values suggest that the tracer was routed through a hydraulically efficient, channelized drainage system. However, detailed analyses reveal a large diurnal variability in terms of transit velocity and dispersion coefficient. This finding underlines the difficulty of detecting a possible drainage system evolution based on single tracer tests conducted at coarse temporal intervals. Furthermore, the obtained velocity-discharge relationships display pronounced hysteresis. We suggest that the evolution of the cross-sectional area of an ice-walled conduit and the modulation of inflow at the junction of a tributary moulin to a main subglacial channel are responsible for the observed behavior.last_img read more

Foraging behaviour and habitat use by brown skuas Stercorarius lonnbergi breeding at South Georgia

May 9, 2021 0 Comments

first_imgTop predators are critical to ecosystem function, exerting a stabilising effect on the food web. Brown skuas are opportunistic predators and scavengers. Although skuas are often the dominant land-based predator at seabird colonies, this is the first detailed study of their movements and activity during breeding. The study was carried out at Bird Island, South Georgia (54°00′S, 38°03′W), in the austral summer of 2011/2012 and included GPS data from 33 breeding adults tracked during the late incubation and early chick-rearing periods. Brown skuas spent on average more than 80 % of time in the territory, and it was extremely rare for both partners to leave the territory simultaneously. Much more time was spent foraging at the coast than in penguin colonies and, based on saltwater immersion data, adults never foraged at sea. None of the tracked birds appeared to specialise in catching small petrels at night. Fewer foraging trips were made per day, and hence, more time was spent in the territory, during incubation than chick-rearing. Despite the pronounced sexual size dimorphism, there were no effects of sex on territorial attendance, foraging time or habitat use. Skuas at Bird Island show higher territorial attendance and are less likely to leave the territory unattended than those breeding elsewhere, suggesting closer proximity to more diverse or abundant food resources than at other colonies. The results tie in with previous diet studies, indicating that brown skuas at this site feed mostly on seal placentae and carrion and that birds may rely on a broader range of food resources as the season progresses.last_img read more

Extreme temperatures in the Antarctic

May 9, 2021 0 Comments

first_imgWe present the first Antarctic-wide analysis of extreme near-surface air temperatures based on data collected up to the end of 2019 as part of the synoptic meteorological observing programs. We consider temperatures at 17 stations on the Antarctic continent and nearby sub-Antarctic islands. We examine the frequency distributions of temperatures and the highest and lowest individual temperatures observed. The variability and trends in the number of extreme temperatures were examined via the mean daily temperatures computed from the 0, 6, 12 and 18 UTC observations, with the thresholds for extreme warm and cold days taken as the 5th and 95th percentiles. The five stations examined from the Antarctic Peninsula region all experienced a statistically significant increase (p < 0.01) in the number of extreme high temperatures in the late Twentieth Century part of their records, although the number of extremes decreased in subsequent years. For the period after 1979 we investigate the synoptic background to the extreme events using ECMWF ERA-Interim reanalysis fields. The majority of record high temperatures were recorded after the passage of airmasses over high orography, with the air being warmed by the Föhn effect. At some stations in coastal East Antarctica the highest temperatures were recorded after air with a high potential temperature descended from the Antarctic plateau, resulting in an airmass 5-7°C warmer than the maritime air. Record low temperatures at the Antarctic Peninsula stations were observed during winters with positive sea ice anomalies over the Bellingshausen and Weddell Seas.last_img read more

Dixie State Volleyball Adds Libero

May 8, 2021 0 Comments

first_img Tags: Dixie State Volleyball/Hannah Waddell/Pleasant Grove Vikings/Radford Highlanders/Robyn Felder FacebookTwitterLinkedInEmailST. GEORGE, Utah-Tuesday, Dixie State women’s volleyball coach Robyn Felder announced the signing of a libero to bolster her team’s defense.Hannah Waddell was extended a scholarship by the Trailblazers, having originally signed early with the Division I Radford Highlanders of the Big South Conference.Waddell starred at Pleasant Grove High School and helped the Vikings to a state title in 2014 and three straight runner-up finishes (2015-17).Waddell finished her scholastic career with 366 digs (3.8 digs per set) and 61 service aces during her senior season.She was also a two-time all-academic region selection for the Vikings.Felder spoke highly of Waddell, saying “Hannah is such a fun athlete to watch. She is fearless and plays with so much energy.” Written by Brad James May 22, 2018 /Sports News – Local Dixie State Volleyball Adds Liberolast_img read more

UVU Men’s Golf Hosts 25th Annual Golf Classic

May 8, 2021 0 Comments

first_img Brad James FacebookTwitterLinkedInEmailSARATOGA SPRINGS, Utah-Wednesday, Utah Valley University’s men’s golf squad hosted its 25th annual golf classic.At the Talons Cove Golf Club of Saratoga Springs, 136 golfers participated with all proceeds benefiting the Utah Valley University student-athlete scholarship fund.Coaches and student-athletes from all 16 of the Wolverines’ Division I sports were on hand, interacting with Wolverine Club members with games, giveaway tips and encouragement.All told, $37,000 was raised to benefit UVU athletics.The win was earned by foursome Dave Rogers, Aaron Smith, Kurt Merrill and Kevin Ford who netted a team score of 52. Tags: Aaron Smith/Dave Rogers/Kevin Ford/Kurt Merrill/Talons Cove Golf Club/UVU Men’s Golf Classic Written by August 15, 2018 /Sports News – Local UVU Men’s Golf Hosts 25th Annual Golf Classiclast_img read more

SUU Softball To Hold Tryouts For Walk-on Positions

May 8, 2021 0 Comments

first_imgSeptember 5, 2018 /Sports News – Local SUU Softball To Hold Tryouts For Walk-on Positions Tags: Kathryn Berg Field/Kylee Wolf/SUU Softball FacebookTwitterLinkedInEmailCEDAR CITY, Utah-Wednesday, the Southern Utah University softball team announced tryouts for walk-on positions for the 2019 season September 10 and 11.The tryouts are September 10 at 3:00 p.m. at Kathryn Berg Field. There will be a second day of tryouts Tuesday September 11 at 4:00 p.m.As of September 12, participants can expect to be told if they made the cut or not.Students seeking to participate must bring a copy of a completed physical and their health insurance card (front and back) prior to the first session of Monday tryouts. Without any of this information, students will not be allowed to try out.Any questions or concerns can be sent to assistant coach Kylee Wolf by email at [email protected] Brad James Written bylast_img read more