Biodiversity and terrestrial ecology of a mid-Cretaceous, high-latitude floodplain, Alexander Island, Antarctica

first_imgThe biodiversity and terrestrial ecology of the Late Albian Triton Point Formation (Fossil Bluff Group), Alexander Island, Antarctica is analysed to improve our understanding of polar biomes during the mid-Cretaceous thermal optimum. This formation was deposited on a high-latitude (75°S) floodplain and consists of two facies associations, a lower braided alluvial plain unit and an upper coastal meander-belt unit. Analysis of fossil plants in well exposed palaeosols reveals the existence of spatially complex plant communities. Braidplains supported patchy, low-density (91 trees/ha) stands of podocarp and taxodioid conifers on floodbasin substrates, and conifer–cycadophyte–fern–angiosperm thickets in riparian settings. Coastal meander-belts supported medium density (568 trees/ha) podocarp–araucarian conifer forests on mature floodbasin soils, and fern–angiosperm–ginkgo thickets in riparian settings. Growth-ring analysis indicates plants experienced stressful growing conditions on the braidplain characterized by high-frequency flood events, but more favourable growing conditions on the coastal plain. Additional vegetation disturbances were caused by arthropod–fungal attack, frost and wildfire. In terms of structure, composition, ecology and productivity these predominantly evergreen, broad-leafed conifer forests bear similarities to the extant temperate rainforests of New Zealand.last_img read more

Brines in seepage channels as eluants for subsurface relict biomolecules on Mars?

first_imgWater, vital for life, not only maintains the integrity of structural and metabolic biomolecules, it also transports them in solution or colloidal suspension. Any flow of water through a dormant or fossilized microbial community elutes molecules that are potentially recognizable as biomarkers. We hypothesize that the surface seepage channels emanating from crater walls and cliffs in Mars Orbiter Camera images result from fluvial erosion of the regolith as low-temperature hypersaline brines. We propose that, if such flows passed through extensive subsurface catchments containing buried and fossilized remains of microbial communities from the wet Hesperian period of early Mars (~3.5 Ga ago), they would have eluted and concentrated relict biomolecules and delivered them to the surface. Life-supporting low-temperature hypersaline brines in Antarctic desert habitats provide a terrestrial analog for such a scenario. As in the Antarctic, salts would likely have accumulated in water-filled depressions on Mars by seasonal influx and evaporation. Liquid water in the Antarctic cold desert analogs occurs at -80°C in the interstices of shallow hypersaline soils and at -50°C in salt-saturated ponds. Similarly, hypersaline brines on Mars could have freezing points depressed below -50°C. The presence of hypersaline brines on Mars would have extended the amount of time during which life might have evolved. Phototrophic communities are especially important for the search for life because the distinctive structures and longevity of their pigments make excellent biomarkers. The surface seepage channels are therefore not only of geomorphological significance, but also provide potential repositories for biomolecules that could be accessed by landers.last_img read more

Southern Ocean sea-ice extent, productivity and iron flux over the past eight glacial cycles

first_imgSea ice and dust flux increased greatly in the Southern Ocean during the last glacial period. Palaeorecords provide contradictory evidence about marine productivity in this region, but beyond one glacial cycle, data were sparse. Here we present continuous chemical proxy data spanning the last eight glacial cycles (740,000 years) from the Dome C Antarctic ice core. These data constrain winter sea-ice extent in the Indian Ocean, Southern Ocean biogenic productivity and Patagonian climatic conditions. We found that maximum sea-ice extent is closely tied to Antarctic temperature on multi-millennial timescales, but less so on shorter timescales. Biological dimethylsulphide emissions south of the polar front seem to have changed little with climate, suggesting that sulphur compounds were not active in climate regulation. We observe large glacial–interglacial contrasts in iron deposition, which we infer reflects strongly changing Patagonian conditions. During glacial terminations, changes in Patagonia apparently preceded sea-ice reduction, indicating that multiple mechanisms may be responsible for different phases of CO2 increase during glacial terminations. We observe no changes in internal climatic feedbacks that could have caused the change in amplitude of Antarctic temperature variations observed 440,000 years ago.last_img read more

Spatial and temporal variability in the structure of aggregations of Antarctic krill (Euphausia superba) around South Georgia, 1997-1999

first_imgAntarctic krill are important in the South Georgia (548S 358W) marine ecosystem. They form aggregations that vary widely in packing density (,1 to 1000 s of individuals m23), length (tens to thousands of metres), and height (tens of metres). Acoustic surveys are often used to estimate krill biomass and provide data that give insight into aggregation structure. Using dual-frequency (38 and120 kHz) acoustic data collected during six surveys conducted around South Georgia during the 1997, 1998, and 1999 austral summers, we isolated 2990 aggregations by applying the Shoal Analysis and Patch Estimation System algorithm in Echoview and a krill-length-dependent acoustic identifier (DSv120 – 38). Multivariate cluster (partition) analysis was applied to metrics from each ofthe aggregations, resulting in three aggregation types with an overall proportional split of 0.28 : 0.28 : 0.44. Types 1 and 3 had low mean densities (,2 g m23), whereas Type 2 had a mean density of 94 g m23. Intersurvey differences were found between the effort-corrected numbers of aggregation types (p ¼ 2.5e26), and between on- and off-continental shelf areas (p ¼ 1.5e27), with agreater number of Type 2 aggregations being found on-shelf. The findings suggest intersurvey variation in krill catchability, with krill being more likely to be caught on-shelf.last_img read more

Quantifying the predictability of the timing of jökulhlaups from Merzbacher Lake, Kyrgyzstan

first_imgGlacier-dammed lakes can yield subglacial outburst floods (jo¨kulhlaups) repeatedly.Predicting flood timing is crucial for hazard mitigation, but incomplete understanding of flood-initiationphysics makes this challenging. Here we examine the predictability of the timing of jo¨kulhlaups fromMerzbacher Lake, Kyrgyzstan, using five flood-date prediction models of varying complexity. Thesimplest model, which offers a benchmark against which the other models are compared, assumes thatfloods occur on the same date each year. The other four models predict flood dates using a floodinitiationthreshold approach and incorporate weather forcing (approximated by the output of twoclimate reanalyses) behind the meltwater input to the lake; the most complex of these models accountsfor a moving subglacial water divide beneath the glacier that dams the lake. Each model is optimizedagainst recorded flood dates to maximize its prediction ability. In terms of their flood prediction ability,our two best models are those that assume a variable outburst threshold governed by the rate ofmeltwater input to the lake and the rate of lake-level rise. They excel over the simplest and mostcomplex models and correctly predict flood dates to within �20 days 57.4% of the time. We alsoquantify the impact of weather uncertainty on prediction success. Our findings can inform practicalflood-forecasting schemes and future investigations of flood-initiation physics.last_img read more

LeBron and the Cavs survive Round 1, win Game 7 over Pacers

first_img Written by Beau Lund FacebookTwitterLinkedInEmailPhil Ellsworth/ESPN Images(CLEVELAND) — LeBron James’ perfect record in the first round of the NBA playoffs stays in tact. His 45 points helped lift the Cleveland Cavaliers past the Indiana Pacers 105-101 in Game 7 of their Eastern Conference Quarterfinal matchup.James went back to the locker room before the end of the third quarter was was reportedly diagnosed with cramps, but came back in the fourth to play some important minutes for his team down the stretch.Cavaliers forward Kevin Love had his biggest game of the series, scoring 14 points along with six rebounds. Cleveland also received help from its role players. Center Tristian Thompson had a big game, scoring 15 points and adding ten rebounds for a double double.The Pacers were led by their star Victor Oladipo, who scored 30 in the game, but it was not enough.With the win, LeBron James improved his record in the first round to 13-0 in his career.Cleveland’s next opponent is the top seeded Toronto Raptors, with Game 1 taking place Tuesday in Toronto.Copyright © 2018, ABC Radio. All rights reserved.center_img April 29, 2018 /Sports News – National LeBron and the Cavs survive Round 1, win Game 7 over Pacerslast_img read more

Bees Outlast Rainiers In 10 Innings

first_img FacebookTwitterLinkedInEmail(Tacoma, WA)  —  Francisco Arcia and Dustin Ackley drove in runs in the top of the 10th inning as the Bees outlasted the Rainiers 10-8 in Tacoma.Eric Young Junior, Rymer Liriano, and Jose Miguel Fernandez each homered for Salt Lake in the win.  Ralston Cash came away with the win as the Bees improved to 33-and-22.The series continues through Sunday. Robert Lovell Tags: Baseball/PCL/Salt Lake Bees June 1, 2018 /Sports News – Local Bees Outlast Rainiers In 10 Innings Written bylast_img read more

SUU Men’s Basketball Signs Todd Simon To An Extension

first_imgSeptember 17, 2018 /Sports News – Local SUU Men’s Basketball Signs Todd Simon To An Extension Tags: academic probation/Central Michigan/Debbie Corcum/Southern Utah University men’s basketball/Todd Simon/UNLV Written by Brad James FacebookTwitterLinkedInEmailCEDAR CITY, Utah-Monday, just weeks before practice sessions for Southern Utah University’s men’s basketball commence, head coach Todd Simon was signed to an extension through the 2021-22 season.This announcement was made by SUU athletics director Debbie Corum.The men’s basketball program has improved tremendously since Simon’s arrival from UNLV in the 2016-17 season.He is currently 19-46 (.292) as the head coach of the Thunderbirds’ program, but in his second season, the Thunderbirds more than doubled their wins from his first, increasing from 13 to six.The 13 wins SUU had last season are the most for the program since 2000-01.The community has also appreciated Simon’s influence on the program as the Thunderbirds finished fourth in attendance in the Big Sky Conference last season.Corum spoke glowingly of Simon Monday as well, saying he came to the program at a time when it was in danger of academic probation and has made his student-athletes studious.Simon, a native of Fowler, Mich., has a bachelor’s degree from Central Michigan with a double major in sport studies and management information system in 2003.He earned his master’s in sport education leadership from UNLV in 2010.last_img read more

Snow College Football To Conduct Spring Tryouts

first_img FacebookTwitterLinkedInEmailEPHRAIM, Utah-Snow College head football coach Andrew Mitchell has announced a one-day player tryout for all prospective student athletes on Saturday, April 25, 2020. Participants DO NOT need to be enrolled in the college to participate. Senior (class of 2020) High School students are encouraged to attend.This tryout will allow the Snow College Football staff to evaluate on-field skills and get to know each prospective student athlete in person. The camp will be located at Badger Stadium-Robert Stoddard Field in Ephraim.Registration will be open from 8 a.m.until 9 a.m. with the tryout beginning at 9:30 a.m. and concluding at approximately 12 noon. Registration will take place at the Bergeson Athletic Center in the south endzone of Badger Stadium. All participants must have a current physical in order to tryout. (The physical must have been completed within the past 12 months.)Participants should wear proper workout attire and will need their own cleats. No helmets or shoulder pads are required.The cost to attend the tryout is $40 if pre-registered and can be paid for online at snowbadgers.com or $50 in person the day of tryout.Additionally, you will need to download the registration form and the medical/insurance release form, complete both forms and bring them with you.  You will also need to bring a copy of your insurance card. February 3, 2020 /Sports News – Local Snow College Football To Conduct Spring Tryouts Written by Tags: Snow College football Brad Jameslast_img read more

Murray leads balanced attack as Spurs top Jazz 113-104

first_img FacebookTwitterLinkedInEmailSALT LAKE CITY (AP) — Dejounte Murray had 23 points and seven rebounds, leading a balanced attack that helped the San Antonio Spurs beat the Utah Jazz 113-104.DeMar DeRozan added 18 points and seven assists for the Spurs. LaMarcus Aldridge chipped in 15 points and eight rebounds. San Antonio had six players score in double figures.Rudy Gobert finished with 18 points and 14 rebounds to lead the Jazz. Emmanuel Mudiay chipped in 18 points and Jordan Clarkson added 15 off the bench for Utah.The Jazz had a four-game winning streak end with the loss. Tags: Dejounte Murray/NBA/San Antonio Spurs/Utah Jazz February 21, 2020 /Sports News – Local Murray leads balanced attack as Spurs top Jazz 113-104 Written by Associated Presslast_img read more