Modelling diatom responses to climate induced fluctuations in the moisture balance in continental Antarctic lakes

first_imgThe water chemistry of lake systems on the edge of the Antarctic continent responds quickly to changes in the moisture balance. This is expressed as increasing salinity and decreasing lake water level during dry periods, and the opposite during wet periods. The diatom composition of the lakes also changes with these fluctuations in salinity and lake water depth. This is important, as their siliceous remains become incorporated into lake sediments and can provide long-term records of past salinity using transfer functions. In order to develop transfer functions, diatoms and water chemistry data were inter-calibrated from five different East Antarctic oases, namely the Larsemann Hills, the Bolingen Islands, the Vestfold Hills, the Rauer Islands and the Windmill Islands. Results indicate that salinity is the most important environmental variable explaining the variance in the diatom flora in East Antarctic lakes. In oligo- saline lakes the variance is mainly explained by lake water depth. This dataset was used to construct a weighted averaging transfer function for salinity in order to infer historical changes in the moisture balance. This model has a jack-knifed r(2) of 0.83 and a RMSEP of 0.31. The disadvantage of this transfer function is that salinity changes in oligo- saline lakes are reconstructed inaccurately due to the ‘edge effect’ and due to the low species turnover along the salinity gradient at its lower end. In order to infer changes in the moisture balance in these lakes, a second transfer function using weighted averaging partial least squares ( with two components) for depth was constructed. This model has a jack-knifed r(2) of 0.76 and a RMSEP of 0.22. Both transfer functions can be used to infer climate driven changes in the moisture balance in lake sediment cores from oligo-, hypo-, meso- and hyper-saline lakes in East Antarctic oases between 102-758degreesE. The transfer function for lake water depth is promising to track trends in the moisture balance of small freshwater lakes, where changes in shallow and deep-water sediments are readily reflected in changing diatom composition.last_img read more

The EPICA challenge to the Earth system modeling community

first_imgOne of our major aims as Earth systems scientists is to predict how the Earth will behave in the future, particularly in the face of changes imposed upon it as a result of human activities. These predictions are made using models and concepts that are in part derived from observation of how the system has behaved in the past. However, these observations, which come from paleo-records, are also one important tool for validating the models. The imminent appearance of a new ice core data set presents a unique opportunity for a test of our understanding, particularly of the climate/carbon system. Members of the European Project for Ice Coring in Antarctica (EPICA) and others here present a challenge to the modeling communities and other interested parties. The Vostok ice core record has become an iconic data set. It presents the climate of the last 420 kyr, showing the rise and fall of Antarctic temperature through four complete glacial/interglacial cycles. The most striking finding is that CO2 and CH4, the two most significant greenhouse gases (after water vapor), also rise and fall, in a remarkably similar fashion. When Antarctic temperature is calculated including a correction for the climate of the water vapor source region, the correlation between CO2 and Antarctic temperature over the last 150 kyr has an r2 of 0.89!last_img read more

Year-round tracking of small trans-Saharan migrants using light-level geolocators

first_imgSince 1899 ringing (or banding) remained the most important source of information about migration routes, stopover sites and wintering grounds for birds that are too small to carry satellite-based tracking systems. Despite the large quantity of migrating birds ringed in their breeding areas in Europe, the number of ring recoveries from sub-Saharan Africa is very low and therefore the whereabouts of most small bird species outside the breeding season remain a mystery. With new miniaturized light-level geolocators it is now possible to look beyond the limits of ring recovery data. Here we show for the first time year round tracks of a near passerine trans-Saharan migrant, the European Hoopoe (Upupa epops epops). Three birds wintered in the Sahel zone of Western Africa where they remained stationary for most of the time. One bird chose a south-easterly route following the Italian peninsula. Birds from the same breeding population used different migration routes and wintering sites, suggesting a low level of migratory connectivity between breeding and wintering areas. Our tracking of a near passerine bird, the European Hoopoe, with light-level geolocators opens a new chapter in the research of Palaearctic-African bird migration as this new tool revolutionizes our ability to discover migration routes, stopover sites and wintering grounds of small birds.last_img read more

Cephalopod fauna of South Pacific waters: new information from breeding New Zealand wandering albatrosses

first_imgCephalopods play an important ecological role in the Southern Ocean, being the main prey group of numerous top predators. However, their basic ecology and biogeography is still poorly known, particularly in the lightly sampled Pacific sector of the Southern Ocean. We collected and analysed information on cephalopods in that area, using Antipodean and Gibson’s wandering albatrosses (Diomedea antipodensis antipodensis and D. antipodensis gibsoni, respectively) breeding at Antipodes Islands and Auckland Islands, respectively, in the New Zealand subantarctic islands as samplers, as they are known from tracking studies to cover huge areas of the Pacific sector of the Southern Ocean (Antipodean wandering albatrosses mostly forage east of New Zealand, whereas Gibson’s wandering albatrosses forage west of New Zealand). A total of 9111 cephalopod beaks, from 41 cephalopod taxa, were identified from boluses (voluntarily regurgitated items by chicks). The families Histioteuthidae (e.g. Histioteuthis atlantica) and Onychoteuthidae (e.g. Moroteuthis robsoni) were the most important cephalopods numerically and by reconstructed mass, respectively, in both wandering albatross species. Combining this information with previously gathered data on cephalopods in the Atlantic and Indian sectors of the Southern Ocean, we provide evidence from predators of the circumpolar distribution of numerous key cephalopod species in the Southern Ocean, and provide new information on poorly known cephalopods (i.e. relevance in the diet of wandering albatrosses, sizes consumed, biodiversity in the South Pacific, assemblages according to predator breeding sites) in one of the most remote ocean areas in the planet.last_img read more

SST Dynamics at Different Scales: Evaluating the Oceanographic Model Resolution Skill to Represent SST Processes in the Southern Ocean

first_imgIn this study we demonstrate the many strengths of scale analysis: we use it to evaluate the Nucleus for European Modelling of the Ocean model skill in representing sea surface temperature (SST) in the Southern Ocean by comparing three model resolutions: 1/12°, 1/4°, and 1°. We show that while 4–5 times resolution scale is sufficient for each model resolution to reproduce the magnitude of satellite Earth Observation (EO) SST spatial variability to within ±10%, the representation of ∼100-km SST variability patterns is substantially (e.g., ∼50% at 750 km) improved by increasing model resolution from 1° to 1/12°. We also analyzed the dominant scales of the SST model input drivers (short-wave radiation, air-sea heat fluxes, wind stress components, wind stress curl, and bathymetry) variability with the purpose of determining the optimal SST model input driver resolution. The SST magnitude of variability is shown to scale with two power law regimes separated by a scaling break at ∼200-km scale. The analysis of the spatial and temporal scales of dominant SST driver impact helps to interpret this scaling break as a separation between two different dynamical regimes: the (relatively) fast SST dynamics below ∼200 km governed by eddies, fronts, Ekman upwelling, and air-sea heat exchange, while above ∼200 km the SST variability is dominated by long-term (seasonal and supraseasonal) modes and the SST geography.last_img read more

No evidence for fitness signatures consistent with increasing trophic mismatch over 30 years in a population of European shag Phalacrocorax aristotelis

first_img1. As temperatures rise, timing of reproduction is changing at different rates across trophic levels, potentially resulting in asynchrony between consumers and their resources. The match‐mismatch hypothesis (MMH) suggests that trophic asynchrony will have negative impacts on average productivity of consumers. It is also thought to lead to selection on timing of breeding, as the most asynchronous individuals will show the greatest reductions in fitness.2. Using a 30‐year individual‐level data set of breeding phenology and success from a population of European shags on the Isle of May, Scotland, we tested a series of predictions consistent with the hypothesis that fitness impacts of trophic asynchrony are increasing.3. These predictions quantified changes in average annual breeding success and strength of selection on timing of breeding, over time and in relation to rising sea surface temperature (SST) and diet composition.4. Annual average (population) breeding success was negatively correlated with average lay date yet showed no trend over time, or in relation to increasing SST or the proportion of principal prey in the diet, as would be expected if trophic mismatch was increasing. At the individual level, we found evidence for stabilising selection and directional selection for earlier breeding, although the earliest birds were not the most productive. However, selection for earlier laying did not strengthen over time, or in relation to SST or slope of the seasonal shift in diet from principal to secondary prey. We found that the optimum lay date advanced by almost four weeks during the study, and that the population mean lay date tracked this shift.5. Our results indicate that average performance correlates with absolute timing of breeding of the population, and there is selection for earlier laying at the individual level. However, we found no fitness signatures of a change in the impact of climate‐induced trophic mismatch, and evidence that shags are tracking long‐term shifts in optimum timing. This suggests that if asynchrony is present in this system, breeding success is not impacted. Our approach highlights the advantages of examining variation at both population and individual levels when assessing evidence for fitness impacts of trophic asynchrony.last_img read more

Disentangling the influence of three major threats on the demography of an albatross community

first_imgClimate change, fisheries and invasive species represent three pervasive threats to seabirds, globally. Understanding the relative influence and compounding nature of marine and terrestrial threats on the demography of seabird communities is vital for evidence-based conservation. Using 20 years of capture-mark-recapture data from four sympatric species of albatross (black-browed Thalassarche melanophris, gray-headed T. chrysostoma, light-mantled Phoebetria palpebrata and wandering Diomedea exulans) at subantarctic Macquarie Island, we quantified the temporal variability in survival, breeding probability and success. In three species (excluding the wandering albatross because of their small population), we also assessed the influence of fisheries, oceanographic and terrestrial change on these rates. The Southern Annular Mode (SAM) explained 20.87–29.38% of the temporal variability in survival in all three species and 22.72–28.60% in breeding success for black-browed and gray-headed albatross, with positive SAM events related to higher success. The El Niño Southern Oscillation (ENSO) Index explained 21.14–44.04% of the variability in survival, with higher survival rates following La Niña events. For black-browed albatrosses, effort in south-west Atlantic longline fisheries had a negative relationship with survival and explained 22.75–32.21% of the variability. Whereas increased effort in New Zealand trawl fisheries were related to increases in survival, explaining 21.26–28.29 % of variability. The inclusion of terrestrial covariates, reflecting extreme rainfall events and rabbit-driven habitat degradation, explained greater variability in trends breeding probability than oceanographic or fisheries covariates for all three species. These results indicate managing drivers of demographic trends that are most easily controlled, such as fisheries and habitat degradation, will be a viable option for some species (e.g., black-browed albatross) but less effective for others (e.g., light-mantled albatross). Our results illustrate the need to integrate fisheries, oceanographic and terrestrial processes when assessing demographic variability and formulating the appropriate management response.last_img read more

Clive Walford to the Broncos Would Show Wisdom

first_imgMarch 29, 2018 /Sports News – Local Clive Walford to the Broncos Would Show Wisdom Written by This is a great opportunity for the Broncos to make a sound pickup that won’t break the bank. With the salary cap so stringent, that seems the wisest course of action if you want to enhance your squad. No other players in football can do the things tight ends can do, in terms of blocking and receiving. If you have the opportunity to improve your team, why not do the little things behind the scenes?I once learned an adage in my youth: by small and simple means, great things happen. Andrew Mason also likes him. Sayre Beding[email protected] In any event, we shall see if the Broncos are proactive in trying to acquire him but it would be wise.  If there’s a good tight end to be had, don’t think I will say “No.” I have a man crush on all tight ends, ever since I was in 3rd grade. My journal proves it. Loved Walford coming out of Miami in the 2015 draft … still some upside there, IMO. 61 receptions for 688 yards and six touchdowns in his first two seasons before going 9-80-0 with reduced reps in 2017. https://twitter.com/AdamSchefter/status/978688092541542400 …11:45 AM – Mar 27, 2018Who am I to refute these two great witnesses? Anyway, Walford seems to have a solid work ethic and has six receiving touchdowns in 70 games. For someone who was not the Raiders’ primary tight end, that seems pretty solid to me. FacebookTwitterLinkedInEmail *this is another one of my Predominantly Orange articles, speaking of free agent tight end Clive Walford. Yes, I’ve always had an affinity for tight ends.The Oakland Raiders released tight end Clive Walford Tuesday and it would show wisdom if the Broncos get him. Walford, a 6’4″ 253-pounder in his 4th year out of Miami (Fla.) has made vast strides already.Pro Football Reference reports Walford has greatly improved in his catch percentage. In 2015, his rookie year, he caught 56% of passes thrown to him. In 2016, this increased to 63.5% and in 2017, this went to 69.2%. Brad James This makes a TON of sense for Denver. He excelled under Musgrave, and the #Broncos need a TE who has game experience. https://twitter.com/AdamSchefter/status/978688092541542400 …11:43 AM – Mar 27, 2018 If he continues on this trajectory, he should catch at least 74.5% of balls coming his way. Our blog boss, Sayre Bedinger, is bullish on him. Andrew [email protected] Tags: Andrew Mason/Clive Walford/Denver Broncos/Sayre Bedingerlast_img read more

Utah Women Place 12th, USC Women, Oregon Men, Take Pac-12 Titles

first_img Tags: Caitie Faust/Cravon Gillespie/Oregon Men’s Track/Pac 12/Sara Newton/USC Women’s Track Brad James May 13, 2018 /Sports News – Local Utah Women Place 12th, USC Women, Oregon Men, Take Pac-12 Titles FacebookTwitterLinkedInEmailSTANFORD, Calif.-Sunday, the Utah women’s track and field squad finished its second day of competition at the Pac-12 championships.The Utes finished in 12th place with 15 points, far behind champion USC, as the Trojans netted 170 points as Oregon finished in second with 154 points.For the men, Oregon decisively took the crown, posting 174 points as Stanford was second with 125 points, on their home track.The women’s 100-meter dash crown was won by USC’s Twanisha Terry in 10.96 seconds and Makenzie Dunmore of Oregon won the 200-meter dash title for the Ducks in 22.37 seconds.Kendall Ellis of USC netted another Pac-12 title for her squad in the women’s 400, posting a time of 49.99 seconds, which is a meet record. Incidentally, Makenzie Dunmore, who placed second, also set a meet record posting a time of 50.63 seconds.The women’s 800-meter run was won by Oregon’s Sabrina Southerland in 2:02.18, and her teammate, Jessica Hull, posted a time of 4:21.65 in the women’s 1500-meter run to win the conference title. Also in the women’s 800, Utah’s Caitie Faust and Sarah Newton finished sixth and seventh, respectively.Stanford’s Elise Cranny won the women’s 5000-meter run in a time of 16:28.54 while the women’s 100-meter hurdles championship was taken by USC’s Chanel Brissett in a time of 12.75 seconds.USC’s Anna Cockrell won the women’s 400-meter hurdles race in a time of 56.47 seconds.The USC women also swept the 4 x 100 and 4 x 400 relays in times of 42.85 seconds and 3:30.45 respectively. In the 4 x 400, the Utah women placed seventh, posting a time of 3:42.26.Jessie Maduka of UCLA won the women’s triple jump crown with a leap of 44-07.00.For the men, Oregon’s Cravon Gillespie won the 100-meter dash in a time of 10.05 seconds and Michael Norman of USC won the 200-meter dash in a time of 19.84 seconds. Norman also earned the 400-meter dash crown in a time of 44.40 seconds.Robert Ford of USC won the men’s 800-meter run in a time of 1:49.77 while Oregon’s Sam Frakel is the men’s 1500-meter run champion in a time of 3:40.20.Ben Saarel of Colorado (a graduate of Park City High School) won the men’s 5000-meter run in a time of 14:11.23 and Orego’s Braxton Canady won the men’s 110-meter hurdles crown in a time of 13.57 seconds.Rai Benjamin of USC won the men’s 400-meter hurdles title in a time of 48.46 seconds and the USC men’s 4 x 100 relay squad won the crown in a time of 39.38 seconds. In the 4 x 400 relay, the Arizona Wildcats’ men took the crown in a time of 3:07.46.In the men’s high jump, USC’s Earnie Sears took the title with a leap of 7 feet and 2-50 inches. Sander Moldau of Washington State earned the pole vault crown with a jump of 17-02.25 feet.Damarcus Simpson of Oregon was the men’s long jump champion with a leap of 27-04 feet while California’s Tuomas Kaukolahti won the triple jump crown with a jump of 52-08.25 feet.Finally, in the men’s javelin, UCLA’s Simon Litzell won the Pac-12 title with a toss of 244-03 feet. Written bylast_img read more

Barefield Returning To Runnin’ Utes

first_img Tags: Basketball/Sedrick Barefield/Utah Utes May 30, 2018 /Sports News – Local Barefield Returning To Runnin’ Utes Written by FacebookTwitterLinkedInEmail(Salt Lake City, UT)  —  It looks like Sedrick Barefield will be heading back to the Runnin’ Utes for his senior season.Following his workout with the Jazz yesterday, multiple sources are reporting Barefield has informed the Utah coaching staff he intends to return.Barefield averaged 12 points for the Utes last season and is expected to be the starting point guard moving forward. Robert Lovelllast_img