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Plate tectonics of the Scotia Sea region

first_imgA newly defined small lithospheric plate in the eastern Scotia Sea accounts for the intense seismicity at the South Sandwich Trench.last_img

Calorific values and elemental analysis of eleven species of oceanic squids (Mollusca:Cephalopoda)

first_imgCephalopods may be divided into five types according to their buoyancy. Members of several families such as the Octopodidae, Loliginidae and Ommastrephidae are negatively buoyant and must swim to stay in midwater and are therefore highly muscular animals. Others have mechanisms to make them neutrally buoyant so they can remain suspended in midwater without effort. Nautilus, Spirula and cuttlefishes have low pressure gas-filled chambers and their flesh is muscular and non-buoyant (Denton & Gilpin-Brown, 1973). Squids of one family, the Gonatidae, have a low density oil in their livers to give buoyancy but most of their body is muscular. Some oceanic octopods have very watery tissues in which lighter chloride ions replace sulphate ions (Denton & Shaw, 1961). In 12 of the 26 teuthoid families the buoyancy is provided by low-density ammonia-rich solution in their body and head tissues or in an expanded coelomic cavity (Clarke, Denton & Gilpin-Brown, 1979). These ammoniacal squids are extremely abundant in the oceans of the world and form a large part of the diet of birds, cetaceans, seals and fish (Clarke, 1977). When their biomass is estimated from their utilization by predators it is important to know their properties as food and, in particular, their calorific values. As pointed out by Croxall & Prince in a review of the calorific values of cephalopods (1982), all the known values are of muscular, negatively buoyant species because they are of value as food for humans but no measurements have been made on the ammoniacal or oily species which are probably as important, or even more important, in the economy of the ocean (Clarke, 1983).last_img read more

Large-scale biogeographic patterns in marine mollusks: a confluence of history and productivity?

first_imgLarge-scale biogeographic patterns in marine systems are considerably less well documented and understood than those in terrestrial systems. Here, we synthesize recent evidence on latitudinal and bathymetric gradients of species diversity in benthic mollusks, one of the most diverse and intensively studied marine taxa. Latitudinal gradients in coastal faunas show poleward declines in diversity, but the patterns are highly asymmetrical between hemispheres, and irregular both within and among regions. The extensive fossil record of mollusks reveals that latitudinal gradients have become steeper during the Neogene, partly because of a rapid diversification in tropical coral reefs and their associated biotas. Much of the inter-regional variation in contemporary latitudinal trends depends on the longitudinal distribution of reefs and major Neogene vicariant events. Thus, coastal faunas reveal a strong evolutionary–historical legacy. Bathymetric and latitudinal gradients in the deep ocean suggest that molluscan diversity is a function of the rate of nutrient input from surface production. Diversity may be depressed at abyssal depths because of extremely low rates of organic carbon flux, and at upper bathyal depths and high latitudes by pulsed nutrient loading. While the deep-sea environment is not conducive to fossilization, relationships between local and regional diversity, and the distribution and age of higher taxa indicate an evolutionary signal in present-day diversity gradients. Marine invertebrate communities offer tremendous potential to determine the relative importance of history and ecological opportunity in shaping large-scale patterns of species diversity.last_img read more

Atmospheric decadal variability from high-resolution Dome C ice core records of aerosol constituents beyond the Last Interglacial

first_imgAlong the EPICA Dome C ice core, we measured concentrations of different water-soluble aerosol constituents and deduced total depositional flux records. Here we present high-resolution sodium, calcium, ammonium and nitrate data covering the last 173,000 years. The first three of these species are passive tracers and reveal source and long-range transport changes whereas nitrate is deposited reversibly. However, it can be used to check isotope-derived accumulation rate estimates, a prerequisite to calculate total depositional fluxes. During the last two transitions from glacial to interglacial periods, changes in the total depositional flux differ strongly for different aerosol species. The largest changes are observed in the terrestrial aerosol proxy non-sea salt calcium, only moderate changes occur in the marine sea salt indicator sodium, while ammonium, a proxy for marine bioproductivity, remains rather constant. In agreement with previous studies, we find that only considerable glacial–interglacial changes at both, the terrestrial and the marine sea salt aerosol source can explain the observed pronounced changes. The unprecedented high-resolution of our data allows for the first time the examination of decadal variability back to the penultimate glacial period. On the one hand, we find occasional fast shifts occurring within a few years; here we present such an event in the calcium record from the penultimate glacial period. On the other hand, we examine variation coefficients and pairwise correlation coefficients, both determined in 200-year windows. They generally reveal only moderate changes. During glacial periods, slightly lower variation coefficients are found, concurrent with slightly higher correlation coefficients, which points to a more uniform and stronger coupled atmospheric long-range transport of the different aerosol species to the East Antarctic Plateau and less influence of cyclonic activities during cold periods. The opposite is observed for interglacial periods with probably even reinforced importance of cyclonic influences during the Last Interglacial period, the Marine Isotope Stage 5.5. This period reveals no evidence for abrupt climatic changes in any of the species, however, the marine sea salt aerosol indicator sodium shows a distinct minimum followed by a pronounced increase. This pattern is explained by significantly reduced sea ice production in the Indian Southern Ocean sector, which is believed to be the dominant source of sodium deposited in Dome C during warm periods.last_img read more

Changes in the freshwater composition of the upper ocean west of the Antarctic Peninsula during the first decade of the 21st century

first_imgIn recent decades, the west Antarctic Peninsula (WAP) has warmed more rapidly than anywhere else in the Southern Hemisphere. Associated with this, there has been a marked shortening of the sea ice season, a retreat of the majority of glaciers, and an increase in precipitation. Each of these changes in the freshwater system has the potential to exert significant influence on the ecosystem, via processes such as stabilisation of the upper water column, and supply of micronutrients to the mixed layer. Here we use a time series of hydrographic and stable oxygen isotope (δ18O) measurements collected at a near-coastal site in Marguerite Bay to quantify the prevalence of meteoric freshwater (glacial melt plus precipitation) separately from sea ice melt. During 2002–2009, meteoric water dominated, with summer water column inventories of order 4–6 m. Summer sea ice melt inventories were lower, ranging from −1 to 0.5 m (where a negative value indicates net sea ice formation from this water). In the near-surface layers, we find highest meteoric water prevalence in February 2006 (6%) and lowest in October 2007 (1%), whilst sea ice melt is highest in February 2005 (2%) and lowest in July 2002 (−2%). The ranges in both meteoric water and sea ice melt are significantly larger than derived previously using a subset of the data, reflecting the strong interannual variability present. The largest single determinant of the near-surface freshwater percentages is found to be changes in mixed layer depth. Notably deep layers occurred in the winters of 2003, 2007 and 2008, due to northerly winds associated with El Niño/Southern Oscillation and the Southern Annular Mode. These led to greatly reduced sea ice cover in northern Marguerite Bay, and allowed persistent air-sea heat fluxes and stronger rates of sea ice production, which is a key factor in controlling mixed layer depth. We also discuss the possible role of interannual changes in wind-induced mixing in this context. As climate change at the WAP continues, we expect further changes in each of the components of the freshwater budget, and also changes in the vertical redistribution of this freshwater by oceanographic processes. Our ongoing δ18O monitoring will help track these changes, and elucidate their consequences for the operation of the marine ecosystem.last_img read more

Foraging areas of streaked shearwaters in relation to seasonal changes in the marine environment of the Northwestern Pacific: inter-colony and sex-related differences

first_imgAs the spatial distribution of marine organisms is often affected by seasonal changes, pelagic seabirds may change their foraging areas in response to seasonal changes in the marine environment. Here, we examined the foraging area of streaked shearwaters Calonectris leucomelas, breeding at Sangan (SA) and Mikura Islands (MK), Japan, from spring to summer during pre-laying and incubation periods. Those colonies are located at the north and south of the Northwestern Pacific’s Kuroshio-Oyashio transition area where high seasonal temperature changes are observed,and where, consequently, birds may show comparable responses to such changes. Our results showed that streaked shearwaters from both colonies shifted their foraging areas northwards as the season progressed. The seasonal shift of foraging areas appeared to coincide with the movement pattern of pelagic fishes that migrate northward in association with the increase in water temperature.However, the pattern of seasonal movement differed between the 2 colonies; shearwaters from SA moved their foraging area along the coastal area of the Kuroshio-Oyashio transition, while those from MK moved along the Kuroshio Extension. Our results also indicated sex-related differences in this general pattern: females showed clear seasonal changes in foraging area, while males did not. During the pre-laying period males returned to the colony frequently to defend their nests or mates, andspent less time at sea. Our results suggest that streaked shearwaters changed their foraging areas in response to seasonal changes in the marine environment, although colony location and sex-related differences in reproductive roles may constrain the birds’ responses to seasonal change.last_img read more

The multi-seasonal NOy budget in coastal Antarctica and its link with surface snow and ice core nitrate: results from the CHABLIS campaign

first_imgMeasurements of a suite of individual NOy components were carried out at Halley station in coastal Antarctica as part of the CHABLIS campaign (Chemistry of the Antarctic Boundary Layer and the Interface with Snow). Conincident measurements cover over half a year, from austral winter 2004 through to austral summer 2005. Results show clear dominance of organic NOy compounds (PAN and MeONO2) during the winter months, with low concentrations of inorganic NOy. During summer, concentrations of inorganic NOy compounds are considerably greater, while those of organic compounds, although lower than in winter, are nonetheless significant. The relative concentrations of the alkyl nitrates, as well as their seasonality, are consistent with an oceanic source. Multi-seasonal measurements of surface snow nitrate correlate strongly with inorganic NOy species (especially HNO3) rather than organic. One case study in August suggested that, on that occasion, particulate nitrate was the dominant source of nitrate to the snowpack, but this was not the consistent picture throughout the measurement period. An analysis of NOx production rates showed that emissions of NOx from the snowpack overwhelmingly dominate over gas-phase sources. This result suggests that, for certain periods in the past, the flux of NOx into the Antarctic boundary layer can be calculated from ice core nitrate data.last_img read more

Pussy Riot World Cup protesters get 15-day jail term, 3-year ban from sporting events

first_img Beau Lund July 16, 2018 /Sports News – National Pussy Riot World Cup protesters get 15-day jail term, 3-year ban from sporting events FacebookTwitterLinkedInEmailIan MacNicol/Getty Images(MOSCOW) — Four members of the anti-Vladimir Putin, anti-Donald Trump group Pussy Riot were sentenced to 15 days in jail for participating in a dramatic on-field protest during the World Cup final at Luzhniki Stadium in Moscow on Sunday.Veronika Nikulshina, Olga Kuracheva, Olga Pakhtusova and Petya Verzilov also have been banned from attending sporting events for three years, according the group’s representative, who confirmed the sentences to ABC News on Monday. The group also shared information about each of their member’s sentences in a series of tweets.The Russian punk rock band and arts collective claimed responsibility for the on-field protest during the World Cup 2018 final between France and Croatia.The four members ran onto the field early in the second half dressed as policemen, calling for the release of political prisoners in front of millions tuned in to the final match — including Putin.According to a statement obtained by ABC News from Russian police, the Pussy Riot protesters who stormed the field were charged with administrative offenses — violating the rules of conduct for spectators during the holding of official sporting events and also wearing a police uniform without authorization.In a post published on the group’s official Facebook page, the members claimed responsibility for the protest, explained the significance behind the police imagery and included a list of demands.“Today is 11 years since the death of the great Russian poet, Dmitriy Prigov. Prigov created an image of a policeman, a carrier of the heavenly nationhood, in the russian culture,” the group wrote. “…The heavenly policeman rises as an example of the nationhood, the earthly policeman hurts everyone…The FIFA World Cup has reminded us of the possibilities of the heavenly policeman in the Great Russia of the future, but the earthly policeman, entering the ruleless game breaks our world apart.”In their Facebook post on Sunday, the groups demands included letting “all political prisoners free,” “all political competition in the country,” and to “stop illegal arrests on rallies.”Pussy Riot has been fiercely critical of Putin’s government. The group was launched into the international spotlight in 2012 when three of its original members were charged with hooliganism and sentenced to two years in prison for performing the anti-Putin protest song “Punk Prayer” at a Moscow cathedral.Yekaterina Samutsevich’s sentence was suspended on appeal, but Nadya Tolokonnikova and Maria Alyokhina remained in prison until December 2013.After their release, the activists founded an independent media outlet that advocates for political prisoners and have continued to speak out against Putin and other leaders, including Trump and British Prime Minister Theresa May.“We’ve seen the authoritarian tendencies is parading all around the world as sexually transmitted diseases, and we think it’s time to make connection,” Tolokonnikova told CNN in August 2017. “It’s time to create global people’s movement if we want to find an alternative to this raid of populism, which we’ve seen in my own country, Russia and in America too, Donald Trump, and in the UK, which ended up in Brexit.”Copyright © 2018, ABC Radio. All rights reserved.center_img Written bylast_img read more

BYU’s Childs Earns WCC and NCAA March Madness Player of the Week Honors

first_imgDecember 11, 2018 /Sports News – Local BYU’s Childs Earns WCC and NCAA March Madness Player of the Week Honors Written by Brad James FacebookTwitterLinkedInEmailSAN BRUNO, Calif.-Monday, BYU men’s basketball star junior forward Yoeli Childs netted player of the week honors from both the West Coast Conference and NCAA March Madness, as he became the national player of the week.In wins over Utah State and Utah, Childs amassed 31 points, 9 rebounds and 2.5 steals per game.Childs also shot 70.6 percent from the field in both games and 92.3 percent at the foul line in the wins over the Aggies and Utes.Childs has netted 31 points in three straight games now, for the Cougars. He is the first Cougar to score 30 points in three consecutive games since guard Jimmer Fredette did so in 2011. Tags: BYU Men’s Basketball/Jimmer Fredette/NCAA March Madness/West Coast Conference/Yoeli Childslast_img read more

SUU Football Celebrates Cedar City Night Saturday Against Nationally-Ranked UC Davis

first_img Tags: SUU Football/UC Davis Football FacebookTwitterLinkedInEmailCEDAR CITY, Utah-Saturday, after playing their best game of the season in many respects, in a 29-14 loss to Weber State, Southern Utah (1-6, 0-3 in Big Sky Conference play) hosts No. 22 (STATS FCS)/No. 23 (AFCA Coaches) UC Davis.The Thunderbirds rank 90th nationally in scoring offense (22.1 points per game). Redshirt sophomore quarterback Chris Helbig completes 63.1 percent of his passes on the season (164-260) for 1,703 yards, nine touchdowns and eight interceptions. He has also run for a team-best five touchdowns.Redshirt junior tailback James Felila (74 car, 248 yards, 2 TD’s) and sophomore back Thomas Duckett (6 car, 140 yards, TD) have each carried the rushing burden for the Thunderbirds.Sophomore tailback Lance Lawson (57 rec, 524 yards, 3 TD’s) remains SUU’s overall leading receiver while freshman receiver Zach Nelson (13 rec, 200 yards, 3 TD’s) is tied for the receiving touchdowns lead on the squad. Senior receiver Carlos Baker (6 rec, 132 yards) leads the Thunderbirds with 22 yards per catch.Junior kicker Manny Berz has returned to action, making 1 of 2 field goals on the season in the loss to Weber State. Redshirt junior kicker/punter Kekoa Sasaoka has made 19 of 20 PAT’s for the Thunderbirds.SUU ranks 118th nationally in scoring defense (39.4 points per game). Sophomore defensive lineman Aaron Romero (4 sacks, forced fumble) is among the Thunderbirds’ defensive stalwarts. In interceptions, redshirt senior safety Nathaniel Vaughn, redshirt freshman cornerback Carlton Johnson and junior cornerback Khalid Taylor have a pick apiece on the season.In forced fumbles, redshirt sophomore linebacker Quaid Murray, sophomore defensive end Francis Bemiy and redshirt senior safety Kyle Hannemann each have one in addition to Romero’s.Last Saturday, the Aggies snapped a 3-game losing streak by pummeling Cal Poly 48-24. This was UC Davis’ first Big Sky win of the season.UC Davis ranks 48th nationally in scoring offense (30.3 points per game). Senior signal-caller Jake Maier completes 65.9 percent of his passes on the season (199-302) for 2,243 yards (2nd in the nation) for 18 touchdowns (tied for 8th nationally with Northern Arizona’s Case Cookus and Felix Harper of Alcorn) and nine interceptions.Maier, who ranks fifth nationally with 320.4 yards per game, is only 157 yards away from 10,000 career passing yards. The only other Aggies quarterback to exceed 10,000 yards in his career is former NFL/CFL journeyman signal-caller J.T. O’Sullivan, who starred at UC Davis from 1998-2001.Sophomore tailback Ulonzo Gilliam Jr. (131 car, 607 yards, 6 TD’s) is the Aggies’ leading rusher.Maier has several stellar targets at his disposal. They include sophomore receiver Carson Crawford (33 rec, 428 yards, 3 TD’s), junior wide-out Kris Vaughn (33 rec, 397 yards for a team-best 6 TD’s) and senior tight end Wes Preece (24 rec, 298 yards, 5 TD’s).Graduate student kicker/punter Max O’Rourke has made 8 of his 10 field goal attempts on the season and 24 of his 25 PAT’s for the Aggies.UC Davis is tied for 73rd nationally (29.9 points per game) in scoring defense with Murray State.Redshirt freshman linebacker Nick Eaton (4.5 sacks, four pass breakups, three forced fumbles) is the Aggies’ overall defensive leader.Sophomore defensive back Devon King and junior defensive back Isaiah Thomas have two interceptions apiece for the Aggies. King has also forced three fumbles on the season for UC Davis.The Aggies lead the all-time series against the Thunderbirds 11-9, but SUU has taken six of the last seven contests overall. October 17, 2019 /Sports News – Local SUU Football Celebrates Cedar City Night Saturday Against Nationally-Ranked UC Davis Brad James Written bylast_img read more