The distribution, abundance and seasonality of pelagic marine invertebrate larvae in the maritime Antarctic

first_imgA survey of pelagic larvae was undertaken between November 1992 and February 1995 at Signy Island, Antarctica (60° 43′ S, 45° 36′ W). A diver–towed net and hand–held plankton pump were used at five sites of varying depths (6–30 m) and benthic substrata, in a combination of monthly and fortnightly samples. Overall larval ecological diversity was much higher than expected, with 131 morphologically distinct larval forms collected, apparently representing most of the benthic phyla present. The species richness observed is comparable with levels recorded at temperate latitudes, and higher than Arctic data and the implications for Thorson’s rule (the inferred cline of reduced pelagic larval diversity towards high latitudes) is discussed. Larval abundances were low (mean 2.6 individuals per m3) which were two to six orders of magnitude lower than peaks in comparable data from temperate and tropical zones. We suggest that the low abundances recorded are a reflection of both slow developmental rates and a high dilution of larvae, reducing synchrony and spreading larvae over larger distances. Three seasonal periods, during which different larval types occur, have been identified. Summer, late summer and winter spawning strategies were discernable, and in some groups larvae occurred throughout the year.last_img read more

Oxidized nitrogen chemistry and speciation in the Antarctic troposphere

first_imgUnderstanding the NOy budget at high latitudes is important for our knowledge of present-day clean air chemistry and essential for reliable interpretation of existing ice core nitrate data. However, measurements of NOy components at high latitudes have been limited, and no measurements have attempted to address the budget of NOy. Here we report on a campaign conducted in the austral summer of 1997 at the German Antarctic research station, Neumayer, with first Antarctic measurements for NOy in addition to light alkyl nitrates, NO, HNO3 and p−NO3−. Inorganic nitrate has generally been assumed to be the dominant component of NOy in Antarctica, although this idea has not previously been tested. However, our results show that for this coastal station, methyl nitrate was present in much higher concentration than inorganic nitrate (median CH3ONO2 = 38 pptv, HNO3 = 5 pptv). It has been suggested earlier that some alkyl nitrates might have a marine source. If this suggestion is correct, the implication arises that the oceans are an important source of NOy to the Antarctic troposphere and that their role in determining nitrate concentrations in ice must be considered.last_img read more

Nitrate in Greenland and Antarctic ice cores: a detailed description of post-depositional processes

first_imgA compilation of nitrate (NO(3)(-)) data from Greenland has shown that recent NO(3)(-) concentrations reveal a temperature dependence similar to that seen in Antarctica. Except for sites with very low accumulation rates, lower temperatures tend to lead to higher NO(3)(-) concentrations preserved in the ice. Accumulation rate, which is closely linked to temperature, might influence the concentrations preserved in snow as well, but its effect cannot be separated from the temperature imprint. Processes involved in NO(3)(-) deposition are discussed and shown to be temperature- and/or accumulation-rate-dependent. Apart from scavenging of nitric acid (HNO(3)) during formation of precipitation, uptake of HNO(3) onto the ice crystal’s surface during and after precipitation seems to contribute further to the NO(3)(-) concentrations found in surface snow. Post-depositional loss of NO(3)(-) from the top snow layers is caused by release of HNO(3) and by photolysis of NO(3)(-). It is suggested that photolysis accounts for considerable losses at sites with very low accumulation rates. Depending on the site characteristic, and given that the temperature and accumulation-rate dependence is quantified, it should be possible to infer changes in atmospheric HNO(3) concentrations.last_img read more

Polymetamorphism in the NE Shackleton Range, Antarctica : constraints from petrology and U-Pb, Sm-Nd, Rb-Sr TIMS and in situ U-Pb LA-PIMMS dating

first_imgMetapelitic rock samples from the NE Shackleton Range, Antarctica, include garnet with contrasting zonation patterns and two age spectra. Garnet porphyroblasts in K-rich kyanite-sillimanite- staurolite-garnet-muscovite-biotite schists from Lord Nunatak show prograde growth zonation, and give Sm-Nd garnet, U-Pb monazite and Rb-Sr muscovite ages of 518 +/- 5, 514 +/- 1 and 499 +/- 12 Ma, respectively. Geothermobarometry and P-T pseudo-section calculations in the model system CaO-Na2O-K2O- TiO2-MnO-FeO-MgO-Al2O3-SiO2-H2O are consistent with garnet growth during prograde heating from 540degreesC/7 kbar to 650degreesC/7.5 kbar, and partial resorption during a subsequent P-T decrease to <650degreesC at <6 kbar. All data indicate that rocks from Lord Nunatak were affected by a single orogenic cycle. In contrast, garnet porphyroblasts in K-poor kyanite-sillimanite- staurolite-garnet-cordierite-biotite-schists from Meade Nunatak show two growth stages and diffusion-controlled zonation. Two distinct age groups were obtained. Laser ablation plasma ionization multicollector mass spectrometry in situ analyses of monazite, completely enclosed by a first garnet generation, yield ages of c. 1700 Ma, whereas monazite grains in open garnet fractures and in most matrix domains give c. 500 Ma. Both age groups are also obtained by U-Pb thermal ionization mass spectrometry analyses of matrix monazite and zircon, which fall on a discordia with lower and upper intercepts at 502 +/- 1 and 1686 +/- 2 Ma, respectively. Sm-Nd garnet dating yields an age of 1571 +/- 40 Ma and Rb-Sr biotite analyses give an age of 504 +/- 1 Ma. Integrated geochronological and petrological data provide evidence that rocks from Meade Nunatak underwent a polymetamorphic Barrovian-type metamorphism: (1) garnet 1 growth and subsequent diffusive garnet annealing between 1700 and 1570 Ma; (2) garnet 2 growth during the Ross Orogeny at c. 500 Ma. During the final orogenic event the rocks experienced peak P-T conditions of about 650degreesC/7.0 kbar and a retrograde stage at c. 575degreesC/4.0 kbar.last_img read more

Salp distribution and size composition in the Atlantic sector of the Southern Ocean

first_imgSalp abundance and length frequency were measured during the large-scale CCAMLR 2000 Survey conducted in the Atlantic Sector of the Southern Ocean in the 1999/2000 season. Results from regional surveys around Elephant Island in 1994/95 and 1996/97 seasons also were examined. During the CCAMLR 2000 Survey, salp abundance was higher in the Antarctic Peninsula and South Sandwich Island areas than in the central Scotia Sea. The probable reason for this pattern is a negative relationship with phytoplankton abundance; the central Scotia Sea having greater phytoplankton concentrations than required for optimal salp filter-feeding performance. Cluster analysis of salp size composition resulted in three cluster groups for each of the three surveys. Clusters comprising large salps occurred in warmer waters in all three surveys. The size composition of the salp populations suggests that the timing of intense asexual reproductive budding was earlier in warmer waters. As surface water temperatures generally decrease from north to south, and increase from spring to summer, the general spatio-temporal pattern of asexual reproduction by budding is likely to proceed from north to south as the summer season progresses.last_img read more

Innovative transportable laboratories for Polar science

first_imgThe Netherlands Organisation for Scientific Research and the British Antarctic Survey have built atransportable laboratory facility, named the Dirck Gerritsz Laboratory, to accommodate new scientific research on andfrom the westernAntarctic Peninsula. The design provides a flexible,modular, plug-and-play, innovative and sustainablelaboratory setup. The docking station houses four 20-foot ISO standard high-cube containers, each of which contains adifferent laboratory. Special technological features were used to minimise the environmental impact. The four laboratorycontainers are flexible and can be installed and used as required, and renewed or removedwhen necessary. The containerlaboratories have provided, since opening in 2013, enhanced facilities for global climate change research throughstudying the community composition of phytoplankton; the ecological impact of virus-induced mortality in differentphytoplankton groups; dimethylsulphide and brominated compound fluxes; and CO2 concentrations and trace elementsin sea water. Transportable research laboratory facilities provide an effective and efficient approach for undertakingscientific research in challenging environments and might be the start of a new way of undertaking research, includingexchanging laboratory modules between research stations in Antarctica.last_img read more

An effective treatment in the austere environment? A critical appraisal into the use of intra-articular local anesthetic to facilitate reduction in acute shoulder dislocation

first_imgAcute shoulder dislocation is a common injury in the outdoor environment. The objective of this systematic review of the literature was to determine if intra-articular local anesthetic (IAL) is an effective treatment that could have prehospital application. A methodical search of MEDLINE, PubMed, and EMBASE databases targeted publications from January 1, 1990 until January 1, 2017. Eligible articles compared IAL with other analgesic techniques in patients 16 years or older experiencing acute glenohumeral dislocation. Reduction success, complications, and patient-reported outcome measures underwent comparison. All identified publications originated from the hospital setting. Procedural success rates ranged widely among randomized control trials comparing IAL with intravenous analgesia and sedation (IAL 48–100%, intravenous analgesia and sedation 44–100%). A pooled risk ratio [RR] favored intravenous analgesia and sedation (RR 0.91, 95% confidence interval [CI] 0.84–0.98), but there was significant inconsistency within the analysis (I2 = 75%). IAL provided lower complication rates (4/170, 2%) than intravenous analgesia and sedation (20/150, 13%) (RR 1.11, 95% CI 1.04–1.19, I2 = 63%). One trial found a clinically relevant reduction in visual analogue pain scores when comparing IAL against no additional analgesia in the first minute (IAL 21±13 mm; control 49±15 mm; P<0.001) and fifth minute (IAL 10±10 mm; control 40±14 mm, P<0.001) after reduction. The results suggest that IAL is an effective intervention for acute anterior shoulder dislocation that would have a place in the repertoire of the remote physician. Further research might be beneficial in determining the outcomes of performing IAL in the prehospital setting.last_img read more

Large losses in glacier area and water availability by the end of the twenty-first century under high emission scenario, Satluj basin, Himalaya

first_imgGlaciers in the Satluj river basin are likely to lose53% and 81% of area by the end of the century, ifclimate change followed RCP 8.5 scenario of CNRMCM5and GFDL-CM3 models respectively. The largevariability in area loss can be due to difference intemperature and precipitation projections. Presently,Satluj basin has approximately 2000 glaciers, 1426 sq. kmglacier area and 62.3 Gt glacier stored water. Thecurrent mean specific mass balance is –0.40 m.w.e. a–1.This will change to –0.42 and – 1.1 m.w.e. a–1 by 2090,if climate data of CNRM-CM5 and GFDL-CM3 areused respectively. We have used an extreme scenarioof GFDL-CM3 model to assess the changes in the contributionof glacier melt to the Bhakra reservoir. Massbalance model suggests that glaciers are contributing2 km3 a–1 out of 14 km3 of water. This will increase to2.2 km3 a–1 by 2050, and then reduce to 1.5 km3 a–1 bythe end of the century. In addition, loss in glacier areaby the end of century, will also increase the vulnerabilityof mountain communities, suggesting need forbetter adaptation and water management practices.last_img read more

Super Bowl champ Nick Foles’ new memoir, ‘Believe It’

first_imgJune 26, 2018 /Sports News – National Super Bowl champ Nick Foles’ new memoir, ‘Believe It’ Written by FacebookTwitterLinkedInEmail Leon Bennett/Getty Images(NEW YORK) — Fresh off of his team’s first-ever Super Bowl victory, Philadelphia Eagles’ starting quarterback Nick Foles is out with a new memoir.Foles sustained an ACL injury late in the 2017 NFL season, causing many to believe it was over for the Eagles. Yet, led by Foles, the team went on to win their first-ever Super Bowl in February.In his new book, Foles gives fans an inside look at how he was able to overcome his injuries and other setbacks to become a Super Bowl champion.Foles told “Good Morning America” that in the week leading up to the Super Bowl he was prepared to answer questions about Tom Brady and the Patriots, but keeping the focus on his own team helped them “come out on top.”“It was probably the two toughest weeks of football I’ve gone into preparation for, but it allowed us to keep our head down and focus on our game plan and going out there executing the plays and really just having fun,” Foles said. “Our team plays with so much swag. If you’re in the locker room you see us dancing around before the game, warming up. We play loose and play with high energy and we play for one another and that’s really how we were able to come out on top.”Foles said he told his wife Tori Moore moments after the historic win that their life was about to change, but he made sure their “Friday night date night” would remain a constant.“Being a mom and doing everything she can at the house, that’s a full-time job in and of itself, and I come home [after practice] so we wanted to make sure we had that night to ourselves to go out for a few hours and enjoy one another,” the father of 1-year-old daughter Lily said.“I just knew that with winning a Super Bowl and everyone watching and the platform we have that things will be a little different, but it’s not bad things, it takes some getting used to,” he said. “Keeping our priorities straight, our faith, our family and values will keep us grounded,” he explained.In 2016 Foles contemplated stepping away from football, but he said that time of reflection was pivotal to his growth and overcoming his fears.“When I was going to step away it was a time for me to step back and reflect on just the journey of my life and, you know, what God has done in my life and it was really humbling,” he said.“It was not easy but I was able to come out of it learning a lot and overcoming some fears I had and I think we all have fears we face and — to overcome them and attack them allows us to grow. That’s what I talk about in the book and share with young players and kids.”Copyright © 2018, ABC Radio. All rights reserved.center_img Beau Lundlast_img read more

Adams’ double-double helps S. Utah beat Weber St. 90-82, OT

first_imgHarding led the Wildcats with 27 points. January 5, 2019 /Sports News – Local Adams’ double-double helps S. Utah beat Weber St. 90-82, OT Adams, who redshirted last season after transferring from Arizona State, has back-to-back double-doubles — the first two of his career. Cameron Oluyitan and Dre Marin each had 18 points, Brandon Better added 15 and Jacob Calloway scored nine with 10 rebounds for Southern Utah (6-7, 1-3 Big Sky Conference). The Thunderbirds snapped a six-game losing streak against Weber State and beat the Wildcats for just the ninth time in 41 tries. Written by Associated Press Cody John’s 3-pointer gave Weber State a six-point lead with three minutes left in regulation but SUU scored eight of the last 10 points to force OT. Tags: Andre Adams/Big Sky/SUU Thunderbirds Basketball/Weber State Wildcats Basketball FacebookTwitterLinkedInEmailOGDEN, Utah (AP) — Andre Adams tied his career best with 18 points and grabbed a career-high 11 rebounds to help Southern Utah beat Weber State 90-82 in overtime Saturday night and snap a four-game skid. Jerrick Harding’s 3-pointer gave Weber State (9-6, 3-1) a one-point lead just 29 seconds into overtime but Marin answered with a 3 and then hit two free throws to spark 14-3 run that made it 86-76 when he made two more foul shots with 52 seconds remaining.last_img read more