The summertime plankton community at South Georgia (Southern Ocean): comparing the historical (1926/27) and modern (post 1995) records.

The earliest comprehensive plankton sampling programme in the Southern Ocean was 32 undertaken during the early part of last century by Discovery Investigations to gain a 33 greater scientific understanding of whale stocks and their summer feeding grounds. An 34 initial survey was carried out around South Georgia during December 1926 and January 35 1927 to describe the distribution of plankton during the summer, and to serve as a 36 baseline against which to compare future surveys. We have reanalysed phytoplankton and 37 zooplankton data from this survey and elucidated patterns of community distribution and 38 compared them with our recent understanding of the ecosystem based on contemporary 39 data. Analysis of Discovery data identified five groups of stations with characteristic 40 phytoplankton communities which were almost entirely consistent with the original 41 analysis conducted by Hardy and Gunther (1935). Major groupings were located at the 42 western end of the island and over the northern shelf where Corethron spp. were 43 dominant, and to the south and east where a more diverse flora included high abundances 44 of Nitzschia seriata. Major zooplankton-station groupings were located over the inner 45 shelf which was characterised by a high abundance of Drepanopus forcipatus and in 46 oceanic water >500 m deep that were dominated by Foraminifera, Oithona spp., 47 Ctenocalanus vanus, and Calanoides acutus. Stations along the middle and outer shelf 48 regions to the north and west, were characterised by low overall abundance. There was 49 some evidence that groupings of stations to the north of the island originated in different 50 water masses on either side of the Southern Antarctic Circumpolar Current Front, the 51 major frontal system in the deep ocean close to South Georgia. However, transect lines 52 during 1926/27 did not extend far enough offshore to sample this frontal region 53 3 adequately. Interannual variability of zooplankton abundance was assessed from stations 54 which were sampled repeatedly during 7 recent British Antarctic Survey cruises (1995-55 2005) to the region and following taxonomic harmonization and numerical 56 standardization (ind. m-3), a subset of 45 taxonomic categories of zooplankton (species 57 and higher taxa) from 1926/27, were compared with similar data obtained during the 58 BAS cruises using a linear model. Initially comparisons were restricted to BAS stations 59 that lay within 40 km of Discovery stations although a comparison was also made using 60 all available data. Despite low abundance values in 1926/27, in neither comparison did 61 Discovery data differ significantly from BAS data. Calculation of the percentage 62 similarity index across cruises did not reveal any systematic differences in species 63 composition between 1926/27 and the present. In the light of ocean warming trends, the 64 existence of more subtle changes in species composition is not ruled out, but an absence 65 of finely resolved time-series data make this impossible to determine

Consequences of late breeding on moult and recovery rate of a long-distance migrant, the Wheatear (Oenanthe oenanthe)

Unsere Studie hat am Steinschmätzer die Folgen einer verlängerten Brutzeit durch zusätzliche Spätbruten für das Zeitmanagement von Weitstreckenziehern untersucht. Wir fragten, ob der Zeitverlauf der Mauser verändert wird, ob saisonale Aktivitäten verschachtelt werden und ob die Geschlechter unterschiedlich auf spätes Brüten reagieren. Zudem erwarteten wir eine verminderte Rückkehrrate von Spätbrütern. Die Ergebnisse zeigen, dass Steinschmätzer beider Geschlechter ohne Spätbruten kurz nach dem Ausfliegen der Jungen gleichzeitig mit der Mauser beginnen, während spät brütende Steinschmätzer den Mauserbeginn verzögern. Die Verzögerung ist bei den Weibchen (23 Tage) viel ausgeprägter als bei den Männchen (6 Tage). Infolgedessen überlappten spätbrütende Männchen häufig Brut und Mauser, während die Weibchen möglicherweise vor dem Zugbeginn in Zeitdruck gerieten. Trotz des späten Mauserbeginns wechselten Spätbrüter beider Geschlechter ihr Gefieder tendenziell um etwa eine Woche langsamer und konnten somit ihre Verspätung nicht kompensieren. Obwohl zwei Bruten für den Steinschmätzer sicher eine höhere Belastung darstellen, zeigten die Rückkehrraten keine Benachteiligung auf. Unabhängig von Alter, Geschlecht und Anzahl der Bruten lag die Rate im Populationsmittel bei 23,5 %. Vermutlich ziehen nur Steinschmätzer in ausgezeichneter körperlicher Verfassung Spätbruten auf und gleichen die zusätzliche Belastung aus.The present study investigates consequences of late breeding for the seasonal time management of long-distance migrants, as exemplified by the Wheatear. We examined whether the time course of moult was changed, whether seasonal activities were overlapped, and whether the sexes differed in the ways they modified seasonal behaviour when breeding late. Furthermore, we expected that late breeders would incur a cost of additional late breeding by reduced return rates. The results of the study showed that in Wheatears without late clutches both sexes initiated moult simultaneously soon after fledging of the clutch. Late breeders, in contrast, delayed moult onset. The delay was much more pronounced in females (23 days) than males (6 days). As a consequence, late breeding males but not females frequently overlapped breeding and moult, while females may have incurred time pressure to finish moult in time for migration. Despite the late onset of moult, its duration was extended by approximately one week, and therefore, late breeders did not compensate for their seasonal delay. Yet although double clutches are most likely to be demanding, late-breeding Wheatears showed no signs of decreased, but instead, tentatively elevated return rates. Return rates were independent of age, sex, and number of clutches and averaged 23.5 %. We propose that only Wheatears in excellent physical condition initiate additional late clutches and are able to compensate for any arising costs

Junior Recital: Catherine Rothery, flute

This recital is presented in partial fulfillment of requirements for the degree Bachelor of Music in Performance. Ms. Rothery studies flute with Christina Smith.https://digitalcommons.kennesaw.edu/musicprograms/1028/thumbnail.jp

Volcanic thermal features observed by AVIRIS

In July 1991, Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) was flown over Mount Etna and Stromboli, Italy. Lava-filled vents were then present within summit craters of both volcanoes. Since surfaces at magmatic temperatures radiate strongly over the wavelength ranges of the AVIRIS C- and D-spectrometers, it was hoped that the data collected would reveal clear thermal signatures, even of sub-pixel sized features, as have been observed in the 1.65 and 2.22 microns bands of Landsat Thematic Mapper images. This would provide an opportunity to explore the potential of imaging spectrometers for deriving temperature distributions of hot volcanic surfaces. Such research has implications for volcano monitoring in the EOS era, and also for any future AVIRIS deployments above active lava flows, lakes, and domes, where understanding of their behavior may be advanced by detailed thermal observations

Geological mapping of Mawrth Vallis, Mars, by PLANMAP

Mawrth Vallis is generally considered to be the oldest of Mars’ outflow channels. It incises Noachian (> 3.7 Ga) terrain and is associated with thick (> 150 m), clay-bearing deposits. Clays are important astrobiologically because they are potential catalytic substrates for (pre)biotic chemistry and have a high potential to preserve biosignatures. The presence of clay-bearing deposits was an important factor in the decision to shortlist an area adjacent to Mawrth Vallis as a candidate landing site for the ExoMars “Rosalind Franklin” rover, whose mission is to search for signs of ancient life on Mars. Ultimately, Mawrth Vallis was not selected as the ExoMars landing site. The origin and geological context of the clay-bearing deposits is not well understood. Furthermore, the geomorphology of Mawrth Vallis, which records its history of deposition/burial and erosion/exhumation, is also less well-studied compared with its mineralogy. Here, we present our ongoing geological mapping of Mawrth Vallis, which we are conducting to investigate the relationship between the channel and the clay-bearing deposits. We are producing a detailed map of the main Mawrth Vallis channel adjacent to the proposed ExoMars landing ellipse. We will also produce an accompanying geomorphic feature map along the whole length of Mawrth Vallis at a smaller scale. We are creating this map as part of the Planmap project, which aims to provide standards for European researchers to adhere to in order to aid the dissemination of their maps. Planmap is producing exemplar maps of Mercury, the Moon, and Mars, where various datasets (visual images, elevation models, spectra, crater size-frequency distributions) will be fused to make more fully-intergrated geological maps. The abundance and diversity of data types at Mawrth Vallis, in addition to its scientific interest, make this region particularly suitable for Planmap

Geologic mapping of Mawrth Vallis, Mars

Mawrth Vallis, generally counted among Mars’ giant outflow channels, has an atypical geomorphology that is less well-studied than its coinciding, thick (>150m) clay-bearing deposits. Here, we present ongoing work as part of the PLANMAP project to map the geomorphic features along the length of Mawrth Vallis in addition to a detailed map of the channel adjacent to the ExoMars 2018 landing ellipse to establish its history of erosion and deposition and relationship with the clay-bearing deposits

Map of tectonic shortening structures in Chryse Planitia and Arabia Terra, Mars

We present a 1:4,000,000 scale map of tectonic landforms in Chryse Planitia and Arabia Terra, on either side of Mars’ dichotomy. Our study area is a ∼3 million km2 region, transitional between Mars’ highlands and lowlands including Oxia Planum, the landing site of the ExoMars rover. Using a structural mapping approach, we digitised all kilometre-scale tectonic structures at a scale of 1:50,000 using high-resolution data (∼6 m/pixel). Although this region is represented as sparsely tectonised on global tectonic maps, we find evidence of widespread tectonic shortening structures across the region. The shortening structures have a dominant N-S orientation and occur in all globally identified geological units. The structural map contributes to a broader understanding of the geological history of the region and Mars’ wider tectonic history

Natural growth rates in Antarctic krill (Euphausia superba): II. Predictive models based on food, temperature, body length, sex, and maturity stage

We used the instantaneous growth rate method to determine the effects of food, temperature, krill length, sex, and maturity stage on in situ summer growth of krill across the southwest Atlantic sector of the Southern Ocean. The main aims were to examine the separate effects of each variable and to generate a predictive model of growth based on satellite-derivable environmental data. Both growth increments in length on moulting (GIs) and daily growth rates (DGRs, mm d-1) ranged greatly among the 59 swarms, from 0.58–15% and 0.013–0.32 mm d-1. However, all swarms maintained positive mean growth, even those in the low chlorophyll a (Chl a) zone of the central Scotia Sea. Among a suite of indices of food quantity and quality, large-scale monthly Chl a values from SeaWiFS predicted krill growth the best. Across our study area, the great contrast between bloom and nonbloom regions was a major factor driving variation in growth rates, obscuring more subtle effects of food quality. GIs and DGRs decreased with increasing krill length and decreased above a temperature optimum of 0.5°C. This probably reflects the onset of thermal stress at the northern limit of krill’s range. Thus, growth rates were fastest in the ice edge blooms of the southern Scotia Sea and not at South Georgia as previously suggested. This reflects both the smaller size of the krill and the colder water in the south being optimum for growth. Males tended to have higher GIs than females but longer intermoult periods, leading to similar DGRs between sexes. DGRs of equivalent-size krill tended to decrease with maturity stage, suggesting the progressive allocation of energy toward reproduction rather than somatic growth. Our maximum DGRs are higher than most literature values, equating to a 5.7% increase in mass per day. This value fits within a realistic energy budget, suggesting a maximum carbon ration of ~20% d-1. Over the whole Scotia Sea/South Georgia area, the gross turnover of krill biomass was ~1% d-1

A Fermi Surface study of Ba1−x_{1-x}Kx_{x}BiO3_{3}

We present all electron computations of the 3D Fermi surfaces (FS's) in Ba$_{1-x}$K$_{x}$BiO$_{3}$ for a number of different compositions based on the selfconsistent Korringa-Kohn-Rostoker coherent-potential-approximation (KKR-CPA) approach for incorporating the effects of Ba/K substitution. By assuming a simple cubic structure throughout the composition range, the evolution of the nesting and other features of the FS of the underlying pristine phase is correlated with the onset of various structural transitions with K doping. A parameterized scheme for obtaining an accurate 3D map of the FS in Ba$_{1-x}$K$_{x}$BiO$_{3}$ for an arbitrary doping level is developed. We remark on the puzzling differences between the phase diagrams of Ba$_{1-x}$K$_{x}$BiO$_{3}$ and BaPb$_{x}$Bi$_{1-x}$O$_{3}$ by comparing aspects of their electronic structures and those of the end compounds BaBiO$_{3}$, KBiO$_3$ and BaPbO$_3$. Our theoretically predicted FS's in the cubic phase are relevant for analyzing high-resolution Compton scattering and positron-annihilation experiments sensitive to the electron momentum density, and are thus amenable to substantial experimental verification.Comment: 12 pages, 7 figures, to appear in Phys. Rev.