Dive durations in pinnipeds and seabirds

first_imgMany endothermic divers regularly exceed the theoretical limit to the duration of aerobic dives, suggesting that assumptions about either the oxygen storage capacity of tissues or the metabolic rate of divers are wrong. This study examined the frequency distributions of dive durations in five species of endothermic divers from the island of South Georgia, South Atlantic. The theoretical aerobic dive time (TADT), calculated from average field metabolic rates, was exceeded regularly by all species except the Antarctic fur seal (<6% of dives). In contrast, the gentoo penguin exceeded its TADT in 69% of dives and the elephant seal in 91%. The frequency distributions of dive durations were bimodal, most especially in the penguins, with one mode below the TADT and another above the TADT, suggesting two different physiological strategies for diving. Interspecific allometric comparisons of dive durations in endothermic divers showed that, in general, relative dive durations in seabirds were greater than in pinnipeds. Dive durations in pinnipeds scaled approximately to field metabolic rate, whereas in seabirds they scaled most closely to flipper surface area, suggesting that they may be partly limited by the rate and degree of conduction of heat to the water.last_img read more

Antarctic Peninsula sea levels: a real-time system for monitoring Drake Passage transport

first_imgSub-surface pressure (SSP) data from tide gauges at three bases on the Pacific coast of the Antarctic Peninsula, together with SSP information from a bottom pressure recorder deployed on the south side of the Drake Passage, have been used to study the relationships between SSP, Drake Passage transport, and the strength of Southern Ocean zonal winds as represented by the Southern Annular Mode. High correlations were obtained between all parameters, confirming results obtained previously with independent data sets, and demonstrating the value of information from the permanent Rothera base, the southern-most site considered. These are important findings with regard to the design, installation and maintenance of observation networks in Antarctica. In particular, they provide the necessary justification for Antarctic Peninsula tide gauge infrastructure investment in the lead up to International Polar Year. Data delivery from Rothera and Vernadsky is currently being improved and should soon enable the first near real-time system for monitoring Drake Passage transport variability on intraseasonal timescales, an essential component of a Southern Ocean Observing System.last_img read more

Hypolithic colonization of opaque rocks in the Arctic and Antarctic polar desert

first_imgThe colonization of the underside of rocks normally requires that the material is sufficiently translucent to allow the penetration of photosynthetically active radiation. We examined the underside of 950 opaque rocks in sixteen locations in the Arctic for hypolithic colonization by photosynthetic microorganisms. Greater than 90% of rocks were colonized. The mean width of the bands of colonization was 3.1 ± 1.9 cm on Devon Island, and 3.0 ± 1.6 cm on Cornwallis Island. The width of the bands of colonization was less in the interior of frost-sorted polygons compared to their edges (in the arctic location, 0.7 ± 0.8 and 3.6 ± 1.4 cm in the interior and at the edges, respectively), suggesting the importance of frost sorting in enhancing the penetration of light around the edges of rocks to their undersides, and thus allowing colonization by photosynthetic organisms. We observed a similar pattern of colonization in antarctic polygons. The hypolithic habitat provides protection from environmental extremes. We show that within the hypolithic habitat organisms are protected from UV radiation. From radiolabeled carbon uptake measurements we estimate the productivity of the arctic communities to be approximately 0.8 g m−2 a−1, potentially as high as above-ground productivity. We discuss the potential implications of climate change for these communities.last_img read more

Spatial variation in seabed temperatures in the Southern Ocean: implications for benthic ecology and biogeography

first_imgThe Antarctic seabed has traditionally been regarded as cold and thermally stable, with little spatial or seasonal variation in temperature. Here we demonstrate marked spatial variations in continental shelf seabed temperature around Antarctica, with the western Antarctic Peninsula shelf significantly warmer than shelves around continental Antarctica as a result of flooding of the shelf by Circumpolar Deep Water from the Antarctic Circumpolar Current. The coldest shelf seabed temperatures are in the Weddell Sea, Ross Sea, and Prydz Bay as a consequence of seasonal convection associated with strong air-sea heat fluxes and sea-ice formation. These waters constitute the dense precursors of Antarctic Bottom Water, and can descend down the adjacent slope to inject cold water into the Southern Ocean deep sea. Deep sea seabed temperatures are coldest in the Weddell Sea and are progressively warmer to the east. There is a distinct latitudinal gradient in the difference between seabed temperatures on the shelf and in the deep sea, with the deep sea warmer by up to similar to 2 K at high latitudes and colder by similar to 2 K around sub-Antarctic islands. These differences have important consequences for benthic ecology and biogeography, understanding the evolutionary history of the Antarctic marine biota, and the impact of regional climate change.last_img read more

What characterizes planetary space weather?

first_imgSpace weather has become a mature discipline for the Earth space environment. With increasing efforts in space exploration, it is becoming more and more necessary to understand the space environments of bodies other than Earth. This is the background for an emerging aspect of the space weather discipline: planetary space weather. In this article, we explore what characterizes planetary space weather, using some examples throughout the solar system. We consider energy sources and timescales, the characteristics of solar system objects and interaction processes. We discuss several developments of space weather interactions including the effects on planetary radiation belts, atmospheric escape, habitability and effects on space systems. We discuss future considerations and conclude that planetary space weather will be of increasing importance for future planetary missions.last_img read more

Physiological diversity, biodiversity patterns and global climate change: testing key hypotheses involving temperature and oxygen

first_imgDocumenting and explaining global patterns of biodiversity in time and space have fascinated and occupied biologists for centuries. Investigation of the importance of these patterns, and their underpinning mechanisms, has gained renewed vigour and importance, perhaps becoming pre-eminent, as we attempt to predict the biological impacts of global climate change. Understanding the physiological features that determine, or constrain, a species’ geographical range and how they respond to a rapidly changing environment is critical. While the ecological patterns are crystallizing, explaining the role of physiology has just begun. The papers in this volume are the primary output from a Satellite Meeting of the Society of Experimental Biology Annual Meeting, held in Florence in July 2018. The involvement of two key environmental factors, temperature and oxygen, was explored through the testing of key hypotheses. The aim of the meeting was to improve our knowledge of large-scale geographical differences in physiology, e.g. metabolism, growth, size and subsequently our understanding of the role and vulnerability of those physiologies to global climate warming. While such an aim is of heuristic interest, in the midst of our current biodiversity crisis, it has an urgency that is difficult to overstate.last_img read more

Effects of freeze-thaw cycles on High Arctic soil bacterial communities

first_imgThe projected increase in freeze-thaw frequency associated with warmer temperatures in the High Arctic could affect the dynamics of soil bacterial communities. We report here the effects of freeze-thaw (FT) cycles on High Arctic bacterial communities of soil samples collected from three sites with different depths of snow cover. Analysis of 16S rRNA gene amplicon sequences showed that bacterial diversity in soil sampled under high snow cover were significantly different from those under low snow cover and those with no snow cover, and showed little change in community diversity after nine consecutive FT cycles. Conversely, bacterial diversity in soil samples under low and with no snow cover decreased after the simulated FT cycles. It is therefore likely that reduced snow cover will influence soil bacterial community structure through an increased frequency of freeze-thaw cycling.last_img read more

Los Angeles Lakers fan joins uses billboards to help recruit LeBron James

first_img Beau Lund March 6, 2018 /Sports News – National Los Angeles Lakers fan joins uses billboards to help recruit LeBron James FacebookTwitterLinkedInEmailPhoto by Phil Ellsworth / ESPN Images(LOS ANGELES) — As LeBron James and the Cleveland Cavaliers make their only trip to Los Angeles this weekend, one Lakers fan is turning up the city’s recruiting efforts of the four-time MVP.ESPN reportsd that Jacob Emrani, a personal injury attorney and Lakers season ticket holder, put up four billboards around Los Angeles in an effort to convince James to join his team via free agency. Similar billboards were also erected in Cleveland, to convince James to stay, and in Philkadelphia. The team is not involved with the billboards in any way. That after being fined twice for tampering charges. Each of the billboards bears the hashtag #LABron. One reads “Cleveland & Philly, You Can’t Compete with L.A.” and another reads “FORGET THE PROCESS, WE WIN BANNERS.” The latter is a reference to the Philadelphia 76ers rebuilding efforts that have been nicknamed The Process.Another billboard, Emrani says, features retired Lakers jersey numbers — including those of Kobe Bryant, Shaquille O’Neal and Magic Johnson — with James’ number 23 next to them.Emrani says he has over 50 billboards around Los Angeles, but wouldn’t say how much he paid for the LeBron-focused billboards. He plans on keeping them up for the month, however.“This is a first. If this goes well, I’m planning to do the same thing for Paul George sometime down the road,” Emrani said. “What I am hoping to accomplish is for LeBron to know how badly he is wanted here. … This is going to be the best situation here. We bring him the weather, we bring him his two houses, all of his business partners are out here. His future.”Copyright © 2018, ABC Radio. All rights reserved.center_img Written bylast_img read more

Weber State Football Enters Into Series Against Northern Iowa

first_imgApril 18, 2018 /Sports News – Local Weber State Football Enters Into Series Against Northern Iowa Written by FacebookTwitterLinkedInEmailOGDEN, Utah (Weberstatesports.com) Wednesday, Weber State football announced it has entered into a home and home series with traditional FCS power Northern Iowa for the 2019 and 2020 seasons.The Wildcats and the Panthers, who represent the Missouri Valley Football Conference, will meet at Stewart Stadium September 18, 2019. The Wildcats will return the favor September 19, 2020, when they visit the UNI-Dome at Cedar Falls, Iowa.This announcement completes the 2019 schedule for Weber State as they will open at FBS foe San Diego State to start that season and then return home to face Cal Poly-San Luis Obispo.With the Panthers agreeing to come to Ogden in 2019, this gives the Wildcats six home games for the first time since 2008. Additionally, this also gives the Wildcats six home games against fellow Division I foes for the first time since 2006.Other home games than Northern Iowa and Cal Poly-SLO that season include dates with Southern Utah, Northern Arizona, North Dakota and Idaho State.Weber State director of athletics Jerry Bovee calls this home slate “as competitive a home schedule that we have put together in my time as athletic director” (Bovee became the athletic director in 2009).Northern Iowa has made the FCS playoffs three of the last four seasons and has a rich football heritage as Pro Football Hall of Fame and Super Bowl MVP quarterback Kurt Warner is among their football alumni.Weber State head football coach Jay Hill was also excited by this, saying “it’s important to play quality opponents like Northern Iowa.”The Wildcats and Panthers have met three times in the past, with the teams last meeting in 1991 at Cedar Falls in the first round of the Division I-AA (the former name of FCS) playoffs.The Panthers will be making their first visit to Ogden since September 1978. Tags: Big Sky/FCS/I-AA/Jay Hill/Jerry Bovee/Kurt Warner/Missouri Valley/Northern Iowa/Weber State Brad Jameslast_img read more

Real Salt Lake coach Mike Petke suspended, fined

first_img Written by July 18, 2018 /Sports News – Local Real Salt Lake coach Mike Petke suspended, fined Associated Press FacebookTwitterLinkedInEmailNEW YORK (AP) — Real Salt Lake coach Mike Petke has been suspended an additional game and fined $10,000 by Major League Soccer for on-field misconduct during a game against Minnesota United.The suspension announced Wednesday follows an automatic one-game game ban for being ejected from the Utah club’s 3-1 road loss Saturday night.Petke was fined for abusive and profane language directed at officials, uncontrollable behavior when he was ejected and public criticism of officials during a postgame press conference. Real Salt Lake also was fined $10,000 fine for social media posts.Petke will miss games Saturday night against Colorado and July 28 against San Jose. Tags: Mike Petke/MLS/Real Salt Lake/Soccerlast_img read more