Orr, A., G. J. Marshall, J. C. R. Hunt, J. Sommeria, C.-G. Wang, N. P. M. van Lipzig, D. Cresswell, and J. C. King, 2008: Characteristics of Summer Airflow over the AntarcticPeninsula in Response to Recent Strengthening of Westerly Circumpolar Winds. J. Atmos. Sci., 65, 1396– 1413, doi:10.1175/2007JAS2498.1.
In particular, some penguin populations have responded to the recent changes in sea-ice cover and krill population trends (Fraser et al. 1992; Croxall et al. 2002; Fraser and Hofmann 2003; Forcada et al. 2006; Carlini et al. 2009; Lynch et al. 2010). The Ade´lie (Pygoscelis adeliae), Chinstrap (P. antarctica) and Gentoo (P. papua) penguins appear to be influenced by the inter-annual variability in the sea-ice cover extent (Fraser et al. 1992; Trathan et al. 1996; Ainley et al. 1998; Wilson et al. 2001; Kato et al. 2002; Fraser and Hofmann 2003; Trivelpiece et al. 2011; Lynch et al. 2012). However, contrasting population trends have been recorded between species and localities (Croxall et al. 2002; Trivelpiece et al. 2011; Lynch et al. 2012). For example, Ade´lie penguin populations breeding at the Ross Sea and eastern Antarctica have been increasing during the last decades (Croxall et al. 2002; Kato et al. 2002), while the breeding populations from the AntarcticPeninsula and South Orkney Islands have exhibited a decreasing trend (Croxall et al. 2002; Forcada et al. 2006; Carlini et al. 2009; Lynch et al. 2010). Because Chinstrap penguins (P. antarctica) are essentially confined to the AntarcticPeninsula, almost all the populations showed negative trends during the last decade (Forcada et al. 2006). On the other hand, Gentoo penguins are mainly sub-Antarctic with a subspecies confined to the AntarcticPeninsula (Forcada et al. 2006). The latter species showed a positive popula- tion trend during the last years (Carlini et al. 2009; Lynch et al. 2010). The population trends observed in these pen- guin species seem to be caused by the reduction in the sea- ice cover and krill abundance (Croxall et al. 2002; Fraser and Hofmann 2003; Forcada et al. 2006). However, given the close relationship between sea-ice cover and krill recruitment (Atkinson et al. 2004; Murphy et al. 2007), the exact causal path between climate, food availability and penguin population dynamics may be difficult to decipher. To date there are several studies reporting statistical relationships between climate, krill and penguins abun- dance and demography at Western AntarcticPeninsula ecosystem (Croxall et al. 2002; Atkinson et al. 2004; Forcada et al. 2006; Murphy et al. 2007; Trivelpiece et al. 2011; Lynch et al. 2012). Considering the large amount of previous studies, it is valid to question whether something new can be said about the role of climate warming on population trends of penguins. Although statistical analyses
Abstract. Due to recent atmospheric and oceanic warming, the AntarcticPeninsula is one of the most challenging re- gions of Antarctica to understand in terms of both local- and regional-scale climate signals. Steep topography and a lack of long-term and in situ meteorological observations com- plicate the extrapolation of existing climate models to the sub-regional scale. Therefore, new techniques must be de- veloped to better understand processes operating in the re- gion. Isotope signals are traditionally related mainly to atmo- spheric conditions, but a detailed analysis of individual com- ponents can give new insight into oceanic and atmospheric processes. This paper aims to use new isotopic records col- lected from snow and firn cores in conjunction with existing meteorological and oceanic datasets to determine changes at the climatic scale in the northern extent of the Antarc- tic Peninsula. In particular, a discernible effect of sea ice cover on local temperatures and the expression of climatic modes, especially the Southern Annular Mode (SAM), is demonstrated. In years with a large sea ice extension in winter (negative SAM anomaly), an inversion layer in the lower troposphere develops at the coastal zone. Therefore, an isotope–temperature relationship (δ–T ) valid for all peri- ods cannot be obtained, and instead the δ–T depends on the seasonal variability of oceanic conditions. Comparatively, transitional seasons (autumn and spring) have a consistent
Studied specimens were caught in the three areas sampled during the BENTART cruises: AntarcticPeninsula (AP; 7 stations, 39 specimens), Bellingshausen Sea (BS; 11 st., 32 spec.) and Peter I Island (PI; 2 st., 43 spec.) (Figure 1; Table I). Although the distribution of the specimens across the three areas is apparently homogeneous, three stations (one for each area) contributed almost 65% of specimens, namely st. PI5 (40 spec., 35.1% of total), AP23 (19, 16.7%) and BS37 (14, 12.9%). Furthermore, although the PI stations are within the Bellingshausen Sea, environmental conditions and benthic fauna (particularly assemblages of polychaetes and mollusks) are closer to those found in the AntarcticPeninsula (Troncoso et al. 2007; Sáiz et al. 2008; Troncoso & Aldea 2008; Parapar et al. 2011). The specimens were collected over a wide range of depths (Table I). Those found at shallower depths (< 200 m) were obtained south of the Shetland Islands (AP43, AP47), Peter I Island (PI5, PI6) and Marguerite Bay (AP39), while those collected at greater depths (> 1000 m) were found at stations in the central area of the Bellingshausen Sea (BS3, BS15, BS17, BS31) and off the AntarcticPeninsula (AP42). The bathymetric range is wider than that reported by Micaletto et al. (2003) for the Weddell Sea and King George Island (200–850 m).
The paleofloristic record of King George Island (South Shetland Islands) and the AntarcticPeninsula is discussed including its importance in paleogeographic and paleoclimate reconstructions, stratigraphic correlation, and its influence in the evolution of modern austral floras. Tectonically different from East Antarctic environments by its link with the Mesozoic Pacific subduction process, the AntarcticPeninsula has a history closely linked to that of southernmost South America. This connection persisted until the opening of Drake Passage in the late Paleogene. However, its paleofloristic record -especially in northernmost regions- also shows a great similarity with extant floras in what was eastern Gondwanaland. This similarity is a consequence of the continuous Cretaceous land masses along the Antarctic coast. The fossil record in the AntarcticPeninsula attests to a northwards rejuvenation of the deposits and their floras, beginning in the Triassic in Alexander and Livingston islands with Bennettitales and Cycadales as dominant vegetation. The Early Cretaceous witnessed the arrival of the first angiosperms and at the end of this period and during the Neogene, the explosive diversity of a unique mixed paleoflora of ferns, conifers and angiosperms today dispersed in different southern areas and with exclusive climatic appeals. Located at the northern tip of the AntarcticPeninsula, King George Island documents the events occurred since the Late Cretaceous and due to its location in a fore-arc context -as opposed to those of the James Ross sub-basin- contains a nearly complete record of what occurred in the continental environments of the region during the Early Cenozoic. Plant fossil records are mainly exclusive, and were favoured in their preservation by the volcanic environment that generated the island. Although they show different plant compositions through time, their paleobiomes reveal the persistence of some diagnostic taxa, represented by Nothofagus, podocarps, and Cyatheaceae-Dicksoniaceae as dominant ferns in the under-storey. With the post-Oligocene separation of South America-AntarcticPeninsula and the onset of cold climates, the Paleogene floras declined and nearly disappeared from the continent. In spite of certain heterocrony observed in the dispersion of the austral forest elements among the different landmasses of Gondwana, radiometric data and the regional extension of the deposits allowed the establishment of a coherent chronostratigraphic framework. The relationship between climate and flora and its continuous fossil record make King George Island a good laboratory to investigate changes occurring in this critical part of the world. The plant assemblages of King George Island are central to the understanding of this scenery of drastic tectonic and climatic changes that took place between the end of Mesozoic and the beginning of Cenozoic.
The AntarcticPeninsula (AP) has shown a dramatic warming during the second half of the 20 th century (Vaughan et al. 2003, Thomas et al. 2009, Ding et al. 2011, Schneider et al. 2012). This warming has been attributed to regional changes in atmospheric circulation, particularly to the enhancing of westerlies as a result of a positive trend of the Southern Annular Mode in response to stratospheric ozone depletion (Marshall 2007, Lubin et al. 2008), and an increase of northerly winds as a result of the shift in the position and the strength of Amundsen Sea Low (Hosking et al. 2013, Raphael et al. 2016).
sustained cooling for about 15 years (Turner et al. 2016). Moreover, this recent cooling has been shown to have had some observable effects on the regional cryosphere, including a longer duration of the snow cover, a shift from negative to predominantly positive SMBs and a shift from thickening to thinning of the active layer of permafrost in certain areas of the periphery of the northern AntarcticPeninsula and the South Shetland Islands (Oliva et al. 2017). Consequently, it can be expected that the density of the snowpack may decrease under these cooling conditions. Here, we set out to test if this relatively short period of sustained cooling has been enough to produce a measurable decrease in the density of the snowpack covering the regional glaciers and to verify whether this expected decrease in density is sufficient to have a significant effect on SMB calculations. The latter issue has practical implications, as, if a significant decrease in density does not imply a corresponding significant decrease in the calculated SMB, then time-consuming density measurements do not have to be made during each field campaign.
P. glacincola BNF20 was isolated from a sediment sample collected at King George Island, Antarctica (S62 ◦ 11 0 37.6 00 ; W58 ◦ 56 0 14.9 00 ) during the ECA-48 Chilean Antarctic Expedition (January 2012). Bacteria were grown at 25 ◦ C as described previously (Arenas et al., 2014) in Lysogenic Broth (LB) medium (Sambrook & Russell, 2001) supplemented with tellurite (200 µ g/ml). Strains were identified by sequencing the 16S rRNA gene (accession MF806171) and determining the fatty acid profile. The 16S rRNA gene was sequenced at Pontificia Universidad Católica de Chile using Sanger sequencing with the primers 8F (5 0 -AGAGTTTGATCCTGGCTCAG-3 0 ) (Turner et al., 1999) and 1492R (5 0 -ACGGCTACCTTGTTACGACTT-3 0 ) (Lane, 1991). Fatty acid analyses were carried out at DSMZ, Braunschweig, Germany (Kämpfer & Kroppenstedt, 1996). The strain was deposited at DMSZ (Germany), accession # 102806.
based on the complete sequence of the 18S rRNA gene showed that strain 34-2 belongs to the species T. kinnei with identity of 99%. The phylogenetic analysis evidences a common ances- tor with thraustochytrids isolated of the seashore of Chile (Valparaíso and Puerto Montt) and Australia (Southwest of Tas- mania), strains located on the clade A, particularly T. kinnei |KF709393.1|, Thraustochytriidae sp. |DQ459552.2| and Thraus- tochytriidae sp. |JN675277.1|, respectively (Fig. 2). Therefore, this research provides basic information on the ﬁrst molecular identiﬁcation of this species on the Antarctic Region. Accord- ingly with their sites of isolation, we think that distribution of clade A is a consequence of dynamics of the Southern Hemisphere currents, because Thraustochytrids could live or be transported on hydrochory, such as sediment, senescent macroalgae and fallen mangrove leaves. 10,19 On the other side,
individuals in their exact populations of origin. The slight levels of genetic differentiation reported between Georges Point and the northernmost studied locations coincide with one of the southernmost distributions of chinstrap penguins along the AntarcticPeninsula. Thus, the incipient differentiation may be explained by a founder effect from the northernmost colonies to the south. Although the source colony is expected to present higher genetic diversity values than the newer ones , the genetic diversity indices found here were similar in all sample sites. A similar pattern was observed in the trumpeter finch (Bucanetes githagineus) in peripheral populations . Another observed pattern that could support the hypothesis of chinstrap penguins colonizing new breeding habitats is that they are currently expand- ing their range southward along the AntarcticPeninsula . Numerous studies have reported the presence of small numbers of chinstrap penguins south of their nat- ural breeding range [93–95]. During field work con- ducted in January 2017, this was also observed: two breeding pairs on Waterboat Point (Gabriel González Videla base; 64°49’S, 62°51’W), a single individual surrounded by gentoos on Doumer Island (Yelcho base; 64°65’S, 63°35’W) and another single chinstrap sur- rounded by Adélies on Avian Island (67°46’S, 68°54’W) (Additional file 11: Figure S6). This may suggest that chinstraps tend to prospect other colonies and breeding habitats far away from their colony of origin, similar to that observed in king penguins .
To accomplish this aim, the thesis is organized into three different chapters as follows: 1) in the first chapter the trophic position and energy storage capability of seven distinct species of gorgonians (Primnoisis sp, Fannyella nodosa, Ainigmaptilon antarcticum, Notisis sp., Primnoella sp., Dasystenella sp. and Thouarella sp.) of Austasen and Kapp Norvegia (Esatern Wedell Sea) and AntarcticPeninsula (Western Weddell Sea) were studied in late autumn, to better understand their role in benthic –pelagic coupling processes and the capability to face winter food constraints; 2) in the second chapter the seasonality of trophic relationships of a representative organism of the AntarcticPeninsula (the alcyonarean Anthomastus bathyproctus) was studied, as well as its main prey Salpa thompsoni to better understand the trophic ecology of suspension feeders due to the seasonality of the Antartic waters; and 3) the last chapter pays attention to the climate change effect in various benthic species (Ophiura carinifera, Ophioperla koehleri, Ophionotus victoriae, Pyura bouvetensis, Cnemidocarpa verrucosa, Primnoisis sp., Protelpidia murrayi, Bathyplotes fusciculum and Molpadia musculus) representative of the recently affected Larsen area in the AntarcticPeninsula, using, again different trophic markers that would help to interpret trophic position and food availability depending on the effect of ice cover (and the related primary productivity dynamics).
The present work is largely based on Antarctic specimens collected during the BENTART project (2006 cruise) aboard the R/V Hesperides (2 January to 17 February 2006). A total of 13 stations located in the Bellingshausen Sea and AntarcticPeninsula were sampled using a modified version (Cartes et al. 1994) of the Macer-GIROQ suprabenthic sled (Brunel et al. 1978 ; Dauvin & Lorgere 1989). Description of sampling methodology can be found in San Vicente et al. (2007) and Corbera et al. (2009). Data concerning sampling positions, dates and water depth are reported in Table I. Sorting of samples was carried out onboard and specimens were fixed in 4% formalin and then transferred in 70% ethanol. Specimens used for scanning electron microscopy (SEM) were dehydrated via a graded ethanol series, critical-point dried using CO 2 , covered with gold in a sputter coater and examined and
contrast, is the most common springtail in the AntarcticPeninsula, with a range that extends from northern Alexander Island to include the rest of the western and northern AntarcticPeninsula and Scotia Arc archipel- agos. Moreover, the most ancestral refuge for C.antarcticus is currently suggested to be in the South Shetland Islands (McGaughran et al., 2010), whose divergence is estimated 1.1–1.7 million ybp, which is at least one million years before F. octo-oculata colonised this archipelago (Carapelli et al., 2017). Therefore, the range overlap and the large difference in time of diversification between these two species makes them good candi- date species to identify and distinguish abi- otic and movement factors. Firstly, we used a novel analysis to estimate the realised niches from their occurrences, which we expected to be wider for C.antarcticus as it has a larger native range. Then, we assessed the poten- tial role of wind in the range expansion of both species. Given the existing range of C.antarcticus, we anticipated strong wind connection from the South Shetland Islands to other regions of the AntarcticPeninsula. Nonetheless, if so, we predicted that such connection should be directed towards the north-east, as south-westerly winds prevail in the region. The study analyses identified areas that may be suitable for species range expansion, and we propose new regions that might provide appropriate foci for future area protection planning in the light of both rapid regional climate change and increasing human presence in the region.
A lack of knowledge of naturally occurring pathogens is limiting our ability to use the Antarc- tic to study the impact human-mediated introduction of infectious microorganisms have on this relatively uncontaminated environment. As no large-scale coordinated effort to remedy this lack of knowledge has taken place, we rely on smaller targeted efforts to both study present microorganisms and monitor the environment for introductions. In one such effort, we isolated Campylobacter species from fecal samples collected from wild birds in the Ant- arctic Peninsula and the sub-Antarctic island of South Georgia. Indeed, in South Georgia, we found Campylobacter lari and the closely related Campylobacter peloridis, but also dis- tantly related human-associated multilocus sequence types of Campylobacter jejuni. In con- trast, in the AntarcticPeninsula, we found C. lari and two closely related species,
Substrate age can have a dramatic effect on forest productivity and carbon storage by regu- lating soil nutrient abundance . Though Osa ’ s lithology differs widely in age ( > 80 MYA), the influence of parent material age on ACD variation was minimal and only weakly emerged on basalts. That is, ACD is lowest on the oldest Golfito basalts and highest on the younger Vaquedano basalts, but this trend is weak and does not emerge on sedimentary substrates. In the uplands variable geomorphic forces (i.e. uplift, erosion and rainfall) have created a land- scape of high topographic diversity and soil complexity. Across multiple geologic substrates on the Osa Peninsula, Bern et al.  showed that the majority of mineral nutrients in plant fo- liage and actively cycling nutrient pools are derived from bedrock sources, suggesting that other factors may dampen the role of substrate age as a regulator on bedrock nutrient availabil- ity. Soil type appears to play a subtle role in stratifying ACD within basaltic and sedimentary substrates. For basaltic substrates, ACD generally increased in the order of entisols < ultisols < inceptisols (Fig 3B). For sedimentary substrates, ACD generally increased in the order of
extremely challenging, is a demanding task. Proper quality control of the measurements and quality assurance of the data, which are the basis of all scientific use of data, has to be especially well planned and executed. In this paper we show the importance of proper quality assurance and describe the methods used to successfully operate the NILU-UV multichannel radiometers of the Antarctic network stations at Ushuaia, 54S, and Marambio, 64S. According to our experience, even though multichannel instruments are supposed to be rather stable as a function of time, severe drifts can occur in the sensitivity of the channels under these harsh conditions. During 2000 –2003 the biggest drifts were 35%, both at Ushuaia and Marambio, with the sensitivity of the channels dropping at different rates. Without proper corrections in the data, this would have seriously affected the calculated UV dose rates. As part of the quality assurance of the network a traveling reference NILU-UV, which was found to be stable, was used to transfer the desired irradiance scale to the site NILU-UV data. Relative lamp tests were used to monitor the stability of the instruments. Each site NILU-UV was scaled channel by channel to the traveling reference by performing solar comparisons. The method of scaling each channel separately was found to be successful, even though the differences between the raw data of the site NILU-UV and the reference instruments were, before the data correction, as much as 40%. After the correction, the mean ratios of erythemally weighted UV dose rates measured during the solar comparisons in 2000 – 2003 between the reference NILU-UV and the site NILU-UV were 1.007 ± 0.011 and 1.012 ± 0.012 for Ushuaia and Marambio, respectively, when the solar zenith angle varied up to 80. These results make possible the scientific use of NILU-UV data measured simultaneously at quite different locations, e.g., the Antarctic and Arctic, and the method presented is also practicable for other multichannel radiometer networks.
carried out using correlations specifically developed for the Iberian Peninsula by the IGN and already employed by Crespo (2011). The moment magnitudes assigned by the IGN have been maintained, and other moment magnitudes from the literature have also been incorporated (Stich et al, 2003, 2010). It is assumed that earthquake events are Poisson-distributed, which requires removing dependent events. The methodology followed for this purpose is the traditional one of placing a time-space window around the main events to identify those that need to be discarded. The procedure is similar to that proposed by Gardner and Knopoff (1974), modified here using appropriate parameters for the seismicity of the Iberian Peninsula to ensure that the main event is the first one identified in each iteration; a detailed description is offered by Crespo (2011). As a result of the pruning process conducted, 36% of the events were considered dependent and discarded from the database.
The present review represents the first comprehensive report of natural products that have been isolated from marine organisms collected along the coasts of the Yucatan Peninsula, covering literature up to mid-2019. As result of 38 years of investigations of marine organisms that were collected in the Yucatan Peninsula, 66 marine natural products were isolated from 18 species belonging to eight different phyla (Proteobacteria (Acinetobacter sp.), Chordata (ascidian: Stomozoa murrayi (now Stomozoa roseola), Cnidaria (Pterogorgia anceps), Echinodermata (Astichopus multifidus and Holothuria floridana (now H. (Halodeima) floridana)), Mollusca (Conus delessertii (nowConasprella delessertii), Conus spurius, Octopus maya, and Polystira albida), Porifera (Halichondria magniconulosa (now H. (Halichondria) magniconulosa), Haliclona tubifera (now H. (Reniera) tubifera), Spongia tubulifera (now S. (Spongia) tubulifera) and Teichaxinella morcella (now Axinella corrugata)), Rhodophyta (Solieria filiformis), and Phaeophyta (Dictyota ciliolata, Lobophora variegata, Padina sanctae-crucis, and Turbinaria tricostata) (Table 1). Out of the 66 marine natural products identified, 26 correspond to structures that
myth here, and raises questions about the limits of human rationality in explaining both Antarctic space and our own relationship to it. Rationality and objectivity become sterile buzzwords for a project of control, one that seeks to mask political desires behind scientific research ideas (Carruth & Marzec, Glasberg, Gerhardt et al). Science might “be government” (Glasberg “Who goes there?” 61) in Antarctica, but its application has less to do with the (mostly) important scientific goals of the researchers on the ground, and more to do with toxic goals like the aggrandisation of national science programs that have been enrolled into a resurgence of the ideal of territorial empire (Bloom & Glasberg 121; Steinberg). As a result, Herzog’s film casts the Antarctic as a mirror that reflects our own recourse to irrationality under duress. In fact, Herzog shows a strong antipathy towards the application of any rational approach here. Upon leaving McMurdo part of Herzog’s elation relates to escaping the strict overwatch provided by the penitentiary subcontractors that maintain the station, “decent people” who were simply “too concerned” with Herzog’s personal safety to allow him the freedom he felt he needed to make this film. In this way, Herzog begins to explore the idea that rational approaches, and those called upon to apply them, are somehow insufficient to the task of explaining the particular materialities of Antarctic space.
Molecular dynamics simulations of AFPs allowed estab- lishing interaction of Antarctic AFPs from isolates GU3.1.1 and AFP5.1 at the water/ice interface (Fig. 5). Threonine residues seems to be important for this interaction and when radial distribution function of oxygen was calcu- lated and analyzed after 150 ns of molecular simulation, it revealed distinctive antifreeze behaviors among them, sug- gesting a more efficient antifreeze activity for gu3B, due to the radial distribution peaks for ice in presence of this AFP was reduced in comparison to gu3A and afp5A (Fig. 5d–f, blue line), indicating a smaller quantity of water mole- cules in solid state. However, the best binding affinity was observed for gu3A (−19 kcal/mol). In contrast to gu3A and gu3B, afp5A lacks two threonine residues in β3 and β16 that are present in the former and might have influ- ence in the affinity for ice, as can be seen in Fig. 5a where this AFP is irregularly bounded to the ice lattice. However, binding affinity of afp5 is similar to that of gu3B and shows a more regular binding.