Crustal growth of the Antarctic Peninsula by accretion, magmatism and extension

first_imgA subduction-accretion model incorporating new geophysical data is presented to explain the geology of the Antarctic Peninsula from late Palaeozoic to Cenozoic time. According to the model, the peninsula consists of overlapping accretionary, magmatic and extensional regimes that were diachronous across the peninsula and have built the crust to its present form. The crust, which contains a small proportion of sialic basement, was mainly formed by accretionary and magmatic processes and modified to its present shape by extension. The Gondwanide Orogeny for the Antarctic Peninsula is interpreted in terms of the accretionary processes.last_img

The selection of microbial communities by constant or fluctuating temperatures

first_imgThe diversity of bacterial communities isolated from Antarctic lake sediment in chemostats under constant low temperature (8°C) or diurnally fluctuating temperature (1°C to 16°C) was examined. The median optimum temperature for growth of the freshwater bacteria isolated from the fluctuation chemostat was significantly lower (P < 1%) than that for those from the constant temperature chemostat. The diversity of the enriched bacterial community isolated in the chemostat culture subjected to short‐term temperature fluctuations was greater than that enriched under constant temperature. At least 4 different groups of bacteria, that occupied separate ‘temperature niches’, were isolated from the fluctuating chemostat compared to only one group isolated from the stable chemostat. Furthermore, a pseudomonad from the fluctuating chemostat was shown to out‐compete another pseudomonad from the stable chemostat when both were subjected to the fluctuating temperature regime. However, the pseudomonad of constant (8°C) temperature origin out‐competed that isolated under fluctuating conditions when subjected to a stable temperature regime.last_img

Laboratory studies of assimilation and egestion of algal lipid by Antarctic krill — methods and initial results

first_imgImmature Antarctic krill (Euphausia superba Dana) (length 44–48 mm), which had been maintained in an aquarium, were fed dense suspensions of algal culture, either the haptophyte Isochrysis or the diatom Thalassiosira. Following acclimation to this regime, the animals were transferred to identical supplies of the same algal food, pre-labelled with 14C bicarbonate for 16 h. Faecal pellets were collected individually in each experiment. Following transfer to the radiolabelled food, radioactivity appeared in faecal pellets after 30 min for Isochrysis and 55 min for Thalassiosira. Fitting a first-order kinetic model to the time-course of appearance of radiolabel in faecal pellets, showed that gut turnover (mean residence time of material in the gut) was rapid for krill fed on Isochrysis (turnover time = 47 min) whilst krill took longer to process Thalassiosira (turnover time = 256 min). Uptake rate of radiolabel by the two algae differed by an order of magnitude and was inversely related to cell size. Removal of the two algal species by the krill also differed when expressed as either chanages in radiolabel or biomass but overall, similar amounts of lipid were ingested from the two food sources (817 and 615 ng· ml−1 over 12 h for Isochrysis and Thalassiosira, respectively). Assimilation efficiencies for the two algae, calculated on the basis of radiolabelled and total-lipid ingestion and egestion ranged from 63 to 86%. Most of the radioactivity in the fatty acids of Isochrysis was incorporated into C18 compounds, but this distribution did not correspond to the overall mass composition of algal fatty acids. Saturates, 16:1, 18:4 and 20:5 were labelled to a lesser extent. Radiolabelled fatty acids incorporated into krill gut and somatic tissue differed in composition from the original algal fatty acid pool. In particular, there was higher activity in saturates, in 16:3 and 18:4, whilst 18:1, 18:2 and 18:3 were labelled to a lower extent in krill. Overall, fatty acids showed lower specific activity in krill than in algae, except for 16:3. The distribution of radioactivity in faecal pellets showed a character more strongly related to that of the algal food supply than that of the krill, although the high proportion of label in saturates (predominantly 16:0) was derived from the animals. Much of the ingested fatty acids were subsequently catabolised. Taking all the fatty acids, 69% appeared to be lost by this route, indicating the major importance of fatty acids as an energy source for krill. However, some individual fatty acids were conserved, for example saturates and 18:4. In the latter case, biosynthesis from 18:3 is implied. Overall, the study indicates the importance of constructing detailed budgets in understanding the character and dynamics of feeding by Zooplankton and suggests that control of grazing by quality as well as quantity of the food supply may be a crucial aspect of understanding ocean carbon cycling.last_img

Protozoans as a food source for Antarctic krill, Euphausia superba: complementary insights from stomach content, fatty acids, and stable isotopes

first_imgWe studied the diet of Antarctic krill, Euphausia superba, at five stations across the southwest Atlantic sector in summer 2003 by analyzing stomach content, fatty acids, and stable isotopes on the same individuals. Our aim was to examine what each method could contribute to our understanding of krill nutrition and whether differences seen in growth rates were linked to their food. All three methods indicated clear regional differences in diet, but small ontogenetic and sex-related differences. Overall, diatoms were the most abundant item in the stomach, but at three of the stations, tintinnids, large dinoflagellates, and other armored flagellates dominated the identifiable biomass. Copepod remains were rare. Fatty acids profiles gave additional information about feeding on weakly silicified diatoms and athecate heterotrophic dinoflagellates, with the latter being the main food source at one of the stations. Two independent indices of carnivory, d15N and the fatty acid ratio 18:1(n-9)/18:1(n-7), were correlated among krill from the same swarm, suggesting consistent differences in diet between individuals. An internal index of trophic position, (i.e., d15Nglutamic acid-d15Nphenylalanine) underlined the importance of heterotrophic food for the nutrition of krill, even in summer. Highest growth rates of krill were found during a diatom bloom and coincided with a mixed diet, large digestive gland, and fast stomach passage. However, even in a nonbloom, flagellate-dominated system, krill were able to sustain medium growth rates when feeding on heterotrophic dinoflagellates. Each method supplied specific information on krill nutrition, and the true picture is only revealed when the various methods are used together.last_img

Tracking seabirds to identify ecologically important and high risk marine areas in the western North Atlantic

first_imgProtection of the marine environment lags far behind that of terrestrial domains. To help ameliorate this circumstance, top predators are being tracked to identify important ocean habitats, biodiversity hotspots and high risk areas and to assess effects of anthropogenic developments, pollution and environmental perturbations. We used GPS, Global Location Sensors (GLSs) and satellite platform terminal transmitters (PTTs) to track foraging and migrating thick-billed and common murres and northern gannets along with vessel surveys to identify potential Marine Protected Areas, to assess risk and to evaluate the consequences of the recent Gulf of Mexico oil disaster. Multi-year persistent sites of forage fishes generated multi-species predator aggregations. Species- and colony-specific winter inshore and offshore distributions of murres are associated with risks of climate change (ice), by-catch in fishing gear, hunting and oil extraction. Some thick-billed murres wintered in oceanic areas beyond the continental slope, and an area of high biological diversity was identified west of the Mid-Atlantic Ridge that, owing to its location beyond national jurisdictions, presents unique challenges for protection. Migration research indicated a substantial proportion of the North American gannet population wintering in the Gulf of Mexico near the Deepwater Horizon pollution area. Northern gannets incurred the highest incidence of oiling/recoveries and were the third-most oiled avian species; distributions and exit dates suggest that sub-adult birds suffered much, likely most, of this mortality. Environmental risk is being assessed by tracking combined with stable isotope and blood assays to probe trophic interactions, habitat relationships and to identify and protect biologically significant marine areas.last_img

Amid backlash, Maryland fires football coach a day after reinstatement

first_img FacebookTwitterLinkedInEmailiStock/Thinkstock(COLLEGE PARK, Md.) — The University of Maryland fired head football coach DJ Durkin on Wednesday amid backlash from students and parents over his reinstatement.The school announced Durkin’s departure late Wednesday, just a day after the board of regents concluded he should be reinstated despite the president’s recommendation against it. The board does not have the authority to remove the coach, though the president does.“The chair of the Board of Regents has publicly acknowledged that I had previously raised serious concerns about Coach Durkin’s return,” University of Maryland President Wallace Loh said in a statement. “This is not at all a reflection of my opinion of Coach Durkin as a person. However, a departure is in the best interest of the University, and this afternoon Coach Durkin was informed that the University will part ways.”Durkin had been placed on administrative leave in August amid an investigation into an alleged toxic culture at the school’s football program following the death of 19-year-old Jordan McNair, who suffered heatstroke during a May practice.The coach’s reinstatement sparked an uproar on Tuesday and McNair’s parents said they they were heartbroken by the decision.“I feel like I’ve been punched in the stomach and somebody spit in my face,” his father, Martin McNair, said Tuesday. A community rally had been scheduled for Thursday night to call for Durkin’s firing.Loh, who announced Tuesday he would retire after the current academic year, added that he would devote the remaining months of his presidency to “advancing the needed reforms in our Athletic Department that prioritize the safety and well-being of our student-athletes.”Maryland Gov. Larry Hogan also spoke out Wednesday against the oversight board’s decision, calling for a public hearing into the situation.“I share the concerns of many Marylanders and believe very strongly that more must be done to restore the public trust,” Hogan said. “I am calling on both the University System of Maryland Board of Regents and President Wallace Loh to reconsider their decisions and to schedule a public hearing to address these issues in an open and transparent manner.”“I can and will demand that the university is held accountable for making the reforms they have pledged to put in place with the full transparency that the students, parents, and faculty expect and deserve,” he added.Several players walked out of a team meeting on Tuesday when Durkin’s return was announced by the school’s athletic director, according to ESPN.Copyright © 2018, ABC Radio. All rights reserved. Written by November 1, 2018 /Sports News – National Amid backlash, Maryland fires football coach a day after reinstatementcenter_img Beau Lundlast_img

Virginia faces first time March Madness finalist Texas Tech

first_img FacebookTwitterLinkedInEmailTuelekZa/iStock(MINNEAPOLIS) — The stage is set for Monday night’s NCAA men’s basketball championship.The final will feature an unexpected matchup between No. 1 seed Virginia and No. 3 seed Texas Tech.The game will take place at the U.S. Bank Stadium in Minneapolis beginning at 9:20 p.m. ET.For more on both teams’ road to the final, watch the video below:Copyright © 2019, ABC Radio. All rights reserved. Beau Lund April 8, 2019 /Sports News – National Virginia faces first time March Madness finalist Texas Techcenter_img Written bylast_img

Finally, an easy one: US rolls by Japan 98-45 at World Cup, Mitchell scores 10

first_img Tags: Basketball/FIBA World Cup/Team USA September 5, 2019 /Sports News – Local Finally, an easy one: US rolls by Japan 98-45 at World Cup, Mitchell scores 10 Written by FacebookTwitterLinkedInEmailSHANGHAI (AP) — Jaylen Brown scored 20 points, Kemba Walker added 15 and the U.S. World Cup team finally got to enjoy an easy night, rolling past Japan 98-45 Thursday in the Group E finale.Harrison Barnes scored 14 points while Joe Harris and Donovan Mitchell each had 10 for the Americans (3-0), who are bidding for an unprecedented third consecutive World Cup title.And now, the NBA MVP Giannis Antetokounmpo awaits the Americans as the stakes get higher.The U.S. is headed to a pair of second-round games in Shenzhen, China — with the first one Saturday against Antetokounmpo and Greece. The Greeks claimed the 16th and final second-round berth with a win Thursday night against New Zealand.Yudai Baba scored 18 for Japan (0-3), which will play in classification games the rest of the way. Rui Hachimura, Japan’s best player and the No. 9 draft pick this year by the Washington Wizards, was held to four points on 2 for 8 shooting.A U.S. program that is accustomed to blowout wins, particularly when it has NBA players, hadn’t enjoyed one yet in six games against international competition this summer. The biggest victory margin before Thursday was 21 in the World Cup opener against the Czech Republic, and the U.S. came into the group finale with a plus-59 scoring differential in four exhibitions and two World Cup games.This one, two days after the Americans needed late-game heroics to beat Turkey 93-92 in overtime, was drama-free.It was 13-0 before Japan scored, 23-9 after a quarter, 56-23 at halftime and 73-25 midway through the third quarter when Hachimura got loose for a dunk and his first points of the night. Somehow, matters could have been even worse for Japan: The U.S. missed seven of eight shots during one first-quarter stretch and finished shooting 48% for the game.TIP-INSJapan: The Japanese missed their first six shots, and went 5:48 without a field goal until center Nick Fazekas rattled in a short jumper. … Japan doesn’t play the U.S. often, and when the matchup happens it’s one-sided. The Americans are 3-0 against Japan in the Olympics, winning by a combined 183 points (98-40 in 1956, 125-66 in 1960 and 99-33 in 1972). The teams hadn’t previously met in World Cup play.U.S.: The Americans held a 58-33 rebounding edge. … Harris replaced Jayson Tatum in the starting lineup. Tatum is out with a sprained left ankle and isn’t scheduled to be reevaluated again until Monday. … Marcus Smart (left quad strain) also missed the game, so the U.S. was down to 10 healthy players and two of its four Boston Celtics. … The Americans were flying to Shenzhen after the game.3 FOR 3This tournament marks the 36th different Olympics, World Cup or world championships appearance for USA Basketball. The Americans have now started 3-0 in those events 34 times, going 106-2 overall in their opening three matchups of those competitions.POP ON RUIHachimura worked out for Gregg Popovich and the San Antonio Spurs before the draft, and left a positive impression on the U.S. and Spurs coach. “He knows what he can do, puts himself in position to be successful and score, plays D, rebounds, runs the floor,” Popovich said. “He’s got an all-around game. His confidence is growing and he’ll be a fine player, obviously, and have a very long career.”UP NEXTJapan: Faces New Zealand in a classification-round game Saturday at Dongguan, China.U.S.: Faces Greece in a second-round game Saturday at Shenzhen, China. Associated Presslast_img

No. 25 Utah St tops San Jose St 71-59 in conference opener

first_img FacebookTwitterLinkedInEmailJustin Bean had 18 points and 14 rebounds, and No. 25 Utah State bounced back from its first loss of the season by beating San Jose State 71-59 in the Mountain West Conference opener.The Aggies fell 81-73 last week at Saint Mary’s in a matchup between two of the top mid-major teams in the country.They fared much better in their return to the Bay Area by running away from the Spartans in the second half. Associated Press December 5, 2019 /Sports News – Local No. 25 Utah St tops San Jose St 71-59 in conference opener Written by Tags: Mountain West/Utah State Aggies Basketballlast_img

Salt Lake City, Barcelona among Winter Olympic host options

first_img Associated Press Written by January 10, 2020 /Sports News – Local Salt Lake City, Barcelona among Winter Olympic host options Tags: IOC/Olympics/Salt Lake City/Salt Lake City 2030 Olympics FacebookTwitterLinkedInEmailThe IOC is in talks with three possible bidders to host the Winter Olympics in the future.Former Winter Games hosts Salt Lake City and Sapporo were confirmed along with 1992 Summer Games host Barcelona. The Catalonian city would spread events across the Pyrenees region and look for venues outside Spain for sliding and ski jumping.A new Olympic selection process keeps up a rolling dialogue with possible candidates who can now be selected many years in advance.Previous hosting elections had to be seven years before the games. The 2024 Winter Youth Olympics were awarded to the Gangwon region of South Korea.last_img