Use of cloacal sexing techniques in mark-recapture estimates of breeding population size in Wilson’s stormpetrel Oceanites oceanicus at South Georgia

first_imgMany stormpetrel species breed in habitats where their populations cannot be estimated by direct counts of burrows or birds; mark-recapture experiments have been confounded by the presence of many wandering non-breeders. With a population of Wilson’s Stormpetrel Oceanites oceanicus at Bird Island, South Georgia, we tried to estimate the proportion of breeding females in samples obtained during a mark-recapture experiment. These were identified by measurements of the cloaca, which greatly enlarges at egg-laying. A concurrent experiment with individually marked birds determined that breeding females could be discriminated from males and non-breeders for c 30 days after laying. The technique is probably applicable to other petrels, though it will work best with those that lay most synchronously. The overall population estimate was 4841–5515 birds (SE 856–1417); estimates of breeding females gave a population of 2300 paris early in the incubation period and 1400 pairs near hatching.last_img read more

Temporal plankton dynamics in an oligotrophic maritime Antarctic lake

first_img1 The population density, diversity and productivity of the microbial plankton in an oligotrophic maritime Antarctic lake were studied for a 15-month period between December 1994 and February 1996.2 In the lake, concentrations of nutrients and dissolved organic carbon were uniformly low, temperature varied over a small annual range of 0.1–3 °C, and the surface was ice-covered except during a period of approximately 6 weeks in summer.3 The total of 57 morphotypes of protozoa observed during the study is a higher taxonomic diversity than previously reported from continental Antarctic lakes, but lower than that found in more eutrophic maritime Antarctic lakes. Likewise, planktonic abundance and productivity were lower than has been reported in other lakes on Signy Island, but generally higher than those of lakes on the Antarctic continent.4 There were marked seasonal and interannual variations in planktonic population density.5 Chlorophyll a concentrations ranged from undetectable to 4.2 µg L-1 and the greatest rate of primary productivity measured was 4.5 mg C m-3 h-1. The phytoplankton was dominated by small chlorophytes and chrysophytes, with phototrophic nanoflagellate abundance ranging from 1.1 × 103 to 1.2 × 107 L-1.6 Bacterial densities of 3.6 × 108 to 1.9 × 1010 L-1 were recorded and bacterial productivity reached a peak of 0.36 µg C L-1 h-1. Numbers of heterotrophic nanoflagellates between 5.0 × 104 and 1.8 × 107 L-1, and of ciliates from undetectable to 1.1 × 104 L-1 were observed. Naked amoebae were usually rare, but occasionally reached peaks of up to 1.5 × 103 L-1.last_img read more

Experimental studies of ice nucleation in an Antarctic springtail (Collembola, Isotomidae)

first_imgIce nucleation was studied in field-fresh and acclimated (4°C without food for 11–20 days) samples of thespringtail Cryptopygus antarcticus Willem (Collembola, Isotomidae) at Rothera Research Station, Adelaide Islandon the Antarctic Peninsula. Ice nucleator activity (INA) was measured by a freezing droplet technique in additionto supercooling point (SCP) profiles and polyol, sugar, and water contents. Field and acclimated samplesshowed bimodal SCP distributions with a distinct high group (HG; mean SCP 28 to 210°C) and low group (LG:mean SCP 223 to 225°C), which were significantly different. Acclimation at 4°C increased the proportion of individualsin the LG relative to that in the HG without significant effects on the mean SCP of both groups. INA ofthe HG was significantly greater than that of the LG, and acclimation further reduced the INA of the LG. Thenumber of active ice nucleator agents (INAs) calculated for the HG of field samples increased by 23–100 timesover the temperature range 25 to 28°C compared to only 7 times for the LG over the same range. These differenceswere accentuated in the acclimation experiments. Glucose and galactose were the main carbohydrates inboth field and acclimated springtails, with the latter compound occurring in almost twice the concentration in theLG compared with that in the HG. Acclimation reduced the concentration of both compounds (glucose by 77%and galactose by 54%), whereas water content increased significantly. Digestion of food may have continued duringacclimation at 4°C, which could reduce the LG INA. Lowering of temperature over time is more likely toelicit a cold hardening response than constant temperature acclimation. INA numbers calculated at the nucleationtemperatures for C. antarcticus samples were higher in the LG than in the HG. However, inactivation of INAsmay be a key mechanism underlying cold hardening in this species, either by sequestration within the cellular matrixor by being only seasonally active.last_img read more

Miocene reversal of bottom water flow along the Pacific margin of the Antarctic Peninsula: stratigraphic evidence from a contourite sedimentary tail

first_imgA Fossil Mounded Sedimentary Body (MB) has been identified in the sedimentary record on the central continental rise west of Adelaide Island, on the Antarctic Peninsula Pacific margin. The growth patterns of the MB are defined through a detailed regional stratigraphic analysis using multichannel seismic reflection profiles. The MB has an elongated NE trend. It overlaps and continues to the NE of an extensive cluster of seamounts, and it developed between two non-depositional troughs. Nine seismic units have been identified: Unit 9 (the pre-MB stage), Unit 8 (MB growth stage), Units 7 and 6 (MB maintenance stage), Units 5 and 4 (transitional stage), and Units 3, 2 and 1 (inactive stage). We interpret the MB as a patch drift plastered against the NE, lee side of an obstacle, as a long Contourite Sedimentary Tail (CST), within a deep current that flowed northeastward. This segment of the rise is, however, affected at present by a SW-flowing branch of the Lower Circumpolar Deep Water (LCDW) from the Weddell Sea. The depositional patterns of the MB growth and maintenance stages, which are attributed an early Miocene age on the basis of regional correlation of MCS profiles with DSDP Site 325 and ODP Leg 178 drill sites, provide the first evidence that bottom currents on the central continental rise flowed towards the NE at that time, probably as part of the Lower Circumpolar Deep Water (LCDW) of the Antarctic Circumpolar Current (ACC). We suggest that significant palaeocirculation and palaeoceanographic changes occurred in this area, and probably more widely, during the middle Miocene or at the Miocene/Pliocene boundary. Although these results do not modify the regional stratigraphy of the major sediment drifts found on the continental rise of the Antarctic Peninsula’s Pacific margin, they do indicate that the bottom current regime controlling the development of contourite deposits may have changed over time and also that more than one water mass has probably affected their distribution.last_img read more

Effects of tropical sea surface temperature (SST) errors on the Antarctic atmospheric circulation of HadCM3

first_imgThis paper investigate the large mean sea level pressure errors in the HadCM3 atmosphere-ocean global climate model around Antarctica and finds them to be caused by the sea surface temperature (SST) errors in the winter tropics. This teleconnection is explained by the warm tropical SST anomalies causing anomalous ascent which strengthens the Hadley circulation and increases the high-level (∼200hPa) divergence. This in turn interacts with the strong meridional gradient in absolute vorticity to generate Rossby waves that propagate polewards. By imposing SST anomalies, in the atmosphere only model, in different ocean basins it is shown that it is the SST errors over Indonesia and the eastern tropical Atlantic that are responsible for these wave trains; and hence, primarily responsible for the pressure anomalies. By contrast, a large SST error over the eastern tropical Pacific does not cause a wave train to be generated because it does not generate strong ascent. This study also demonstrates the difficulties in diagnosing errors within a coupled climate model since forcing, particularly in the tropics, may have a strongly non-local effect.last_img read more

Soil bacterial diversity is positively associated with air temperature in the maritime Antarctic

first_imgTerrestrial ecosystems in the maritime Antarctic experienced rapid warming during the latter half of the 20th century. While warming ceased at the turn of the millennium, significant increases in air temperature are expected later this century, with predicted positive effects on soil fungal diversity, plant growth and ecosystem productivity. Here, by sequencing 16S ribosomal RNA genes in 40 soils sampled from along a 1,650 km climatic gradient through the maritime Antarctic, we determine whether rising air temperatures might similarly influence the diversity of soil bacteria. Of 22 environmental factors, mean annual surface air temperature was the strongest and most consistent predictor of soil bacterial diversity. Significant, but weaker, associations between bacterial diversity and soil moisture content, C:N ratio, and Ca, Mg, PO43− and dissolved organic C concentrations were also detected. These findings indicate that further rises in air temperature in the maritime Antarctic may enhance terrestrial ecosystem productivity through positive effects on soil bacterial diversity.last_img read more

Generation of the Mt Kinabalu granite by crustal contamination of intraplate magma modelled by Equilibrated Major Element Assimilation with Fractional Crystallisation (EME-AFC)

first_imgNew geochemical data are presented for the composite units of the Mount Kinabalu granitoid intrusion of Borneo and explore discrimination between crustal- and mantlederivedgranitic magmas. The geochemical data demonstrate that the units making up this composite intrusion became more potassic through time. This was accompanied by an evolution of isotope ratios from a continental-affinity towards a slightly more mantle-affinity (87Sr/86Sri ~0.7078; 143Nd/144Ndi ~0.51245; 206Pb/204Pbi ~18.756 for the oldest unit compared to 87Sr/86Sri ~0.7065, 143Nd/144Ndi ~0.51250 and 206Pb/204Pbi ~18.721 for the younger units). Oxygen isotope ratios (calculated whole-rock δ18O of +6.5–9.3‰) do not show a clear trend with time. The isotopic data indicate that the magma cannot result only from fractional crystallisation of a mantle-derived magma. Alkali metal compositions show that crustal anatexis is also an unsuitable process for genesis of the intrusion. The data indicate that the high-K units were generated byfractional crystallisation of a primary, mafic magma, followed by assimilation of the partially melted sedimentary overburden. We present a new, Equilibrated Major Element – Assimilation with Fractional Crystallisation (EME-AFC) approach for simultaneously modelling the major element, trace element, and radiogenic and oxygen isotope compositions during such magmatic differentiation; addressing the lack of current AFC modelling approaches for felsic, amphibole- or biotite-bearing systems. We propose that Mt Kinabalu was generated through low degree melting ofupwelling fertile metasomatised mantle driven by regional crustal extension in the Late Miocene.last_img read more

An 85K SNP Array Uncovers Inbreeding and Cryptic Relatedness in an Antarctic Fur Seal Breeding Colony

first_imgHigh density single nucleotide polymorphism (SNP) arrays allow large numbers of individuals to be rapidly and cost-effectively genotyped at large numbers of genetic markers. However, despite being widely used in studies of humans and domesticated plants and animals, SNP arrays are lacking for most wild organisms. We developed a custom 85K Affymetrix Axiom array for an intensively studied pinniped, the Antarctic fur seal (Arctocephalus gazella). SNPs were discovered from a combination of genomic and transcriptomic resources and filtered according to strict criteria. Out of a total of 85,359 SNPs tiled on the array, 75,601 (88.6%) successfully converted and were polymorphic in 270 animals from a breeding colony at Bird Island in South Georgia. Evidence was found for inbreeding, with three genomic inbreeding coefficients being strongly intercorrelated and the proportion of the genome in runs of homozygosity being non-zero in all individuals. Furthermore, analysis of genomic relatedness coefficients identified previously unknown first-degree relatives and multiple second-degree relatives among a sample of ostensibly unrelated individuals. Such “cryptic relatedness” within fur seal breeding colonies may increase the likelihood of consanguineous matings and could therefore have implications for understanding fitness variation and mate choice. Finally, we demonstrate the cross-amplification potential of the array in three related pinniped species. Overall, our SNP array will facilitate future studies of Antarctic fur seals and has the potential to serve as a more general resource for the wider pinniped research community.last_img read more

Scoreboard roundup — 5/15/18

first_img Beau Lund FacebookTwitterLinkedInEmailiStock/Thinkstock(NEW YORK) — Here are the scores from yesterday’s sports events:INTERLEAGUE Final Pittsburgh 7 Chi White Sox 0 Final N-Y Mets 12 Toronto 2 Final Minnesota 4 St. Louis 1 N-Y Yankees at Washington 7:05 p.m. Philadelphia at Baltimore 7:05 p.m., postponedAMERICAN LEAGUE Final Oakland 5 Boston 3 Final Detroit 9 Cleveland 8 Final Tampa Bay 6 Kansas City 5 Final Houston 5 L-A Angels 3 Final Seattle 9 Texas 8, 11 InningsNATIONAL LEAGUE Final San Diego 4 Colorado 0 Final Miami 4 L-A Dodgers 2 Final Chi Cubs 3 Atlanta 2 Final Arizona 2 Milwaukee 1 Final San Francisco 5 Cincinnati 3NATIONAL BASKETBALL ASSOCIATION PLAYOFFS Final Boston 107 Cleveland 94 NATIONAL HOCKEY LEAGUE PLAYOFFS Final Tampa Bay 4 Washington 2Copyright © 2018, ABC Radio. All rights reserved. May 16, 2018 /Sports News – National Scoreboard roundup — 5/15/18center_img Written bylast_img read more

Heart-stopping Grand Prix crash highlights life-and-death dangers of race car driving

first_img FacebookTwitterLinkedInEmailiStock/Thinkstock(MACAU, China) — Sophia Floersch’s race car was blazing down the Macau Grand Prix track at 170 mph on Monday when she struck another race car, went airborne and smashed into the photographers’ pit.It took doctors 11 hours to repair the 17-year-old Formula Three driver’s fractured spine.The heart-stopping crash shocked racing fans across the globe. Yet Floersch was one of the lucky ones — she dodged paralysis and will be back behind the wheel “after some time,” Van Amersfoort Racing owner Frits van Amersfoort told the BBC. The implementation of new safety protocols in recent years has driven down the number of motorsports fatalities. But Floersch’s perilous accident was a stark reminder of the risks to drivers competing in the fastest sport in the world — where death and glory race neck-and-neck around every curve.The glamour of champagne showers after a podium win and lucrative paychecks come with the risk of losing it all with one wrong move. Wannabe race car drivers start as young as 8 years old, facing off against their school peers in go-karts. The talented will train for years, spending thousands of dollars to race and get noticed by wealthy teams for Formula One, NASCAR and IndyCar. Competing in the world’s most prestigious races requires extraordinary levels of commitment and patience. Race car drivers Jack Hawksworth and Dominik Baumann talked to ABC News about the mind-boggling number of split-second decisions a driver makes in a race and the long, hard road each traveled to reach the upper ranks of their sport.Hawksworth, 27, and Baumann, 25, recently finished the 2018 season with 3GT Racing, which partnered with luxury automaker Lexus in 2016 to race the Lexus RC F GT3 in the IMSA WeatherTech Sports Car Championship’s GTD class. Hawksworth, a native of Bradford, England, started racing go-karts in 2004 at the age of 13. He spent three seasons racing in the IndyCar series before signing with 3GT Racing.Every week, he’s on a plane, flying to the next track: Daytona. Watkins Glen, New York. Road Atlanta in Georgia.“It’s your life. It’s what I spend all my time doing,” he said. “You want to have to do it.” Routine tasks like shopping and laundry have become “boring,” he admitted — especially so after racing at speeds close to 240 mph.When he’s behind the wheel, strapped in tight and laser focused on the track, Hawksworth is managing real-time data coming from the team’s manager and engineers.“I am constantly bombarded with info,” he said. “They can see a lot more of the race than I can. There’s a very limited view in the car.” The crew tells him when to pull over for a pit stop or to save fuel. He might be instructed to try a new anti-lock braking system. The gap between him and his nearest competitor is calculated and relayed instantly.“It can be very distracting,” Hawksworth said. “I have to be able to use that information and still maintain a high level of performance.”There can be zero distractions on the track for Baumann.“There’s nothing going through my mind during the race,” he said. “I am focusing on my turning and braking points.” This year marks Baumann’s first time competing in the U.S. His parents, who live in Austria, closely follow the team’s demanding schedule, live-streaming the races at home.“My mom watches everything,” he said with a laugh. “Even the practice sessions. They’ll stay awake to watch.”Baumann rarely sees his parents during the season, but he’s had no regrets about joining the team.“It has always been a dream to race in the U.S.,” he said.And it certainly hasn’t been easy for him. Racetracks in the U.S. “have more natural elevation changes, more blind corners and the walls are really close to the tracks,” he explained. “In Europe, the tracks are more flat.” With a different race every weekend, neither Baumann nor Hawksworth get extensive time to practice beforehand. Baumann spends his evenings learning a course from simulations. Hawksworth screens video of past races, taking notes on when to accelerate or how hard to press on the brake. But watching how other drivers have successfully tackled a difficult course only helps so much.“It’s hard to actually replicate what they’re doing,” Hawksworth said. “You look at the data and try to dissect it so you can get faster and better.”Baumann had one serious crash 15 years ago. He broke his collarbone when his go-kart flipped and slammed into a wall. Hawksworth has been involved in a number of crashes, though none were serious. For him, the qualifying laps and actual start of the race are the most intense.“I do a lot of mental preparation to get in the right mindset,” he said. “Before every single race, I visualize all of the laps. I try to visualize all the different situations and potential things that can happen.”Both drivers acknowledge the inherent risks and danger of the sport, yet neither could imagine doing anything else.“It’s an emotional roller coaster,” said Hawksworth. “One million things go into the performance of the driver. I love what I am doing.”Copyright © 2018, ABC Radio. All rights reserved. November 23, 2018 /Sports News – National Heart-stopping Grand Prix crash highlights life-and-death dangers of race car driving Beau Lundcenter_img Written bylast_img read more