ALBERT

Description: Spatial variation in marine oxygen isotope ratios ( δ 18 O) resulting from differential evaporation rates and precipitation inputs is potentially useful for characterizing marine mammal distributions and tracking movements across δ 18 O gradients. Dentine hydroxyapatite contains carbonate and phosphate that precipitate in oxygen isotopic equilibrium with body water, which in odontocetes closely tracks the isotopic composition of ambient water. To test whether dentine oxygen isotope composition reliably records that of ambient water and can therefore serve as a proxy for odontocete distribution and movement patterns, we measured δ 18 O values of dentine structural carbonate ( δ 18 O SC ) and phosphate ( δ 18 O P ) of seven odontocete species ( n  = 55 individuals) from regional marine water bodies spanning a surface water δ 18 O range of several per mil. Mean dentine δ 18 O SC (range +21.2 to +25.5‰ VSMOW) and δ 18 O P (+16.7 to +20.3‰) values were strongly correlated with marine surface water δ 18 O values, with lower dentine δ 18 O SC and δ 18 O P values in high-latitude regions (Arctic and Eastern North Pacific) and higher values in the Gulf of California, Gulf of Mexico, and Mediterranean Sea. Correlations between dentine δ 18 O SC and δ 18 O P values with marine surface water δ 18 O values indicate that sequential δ 18 O measurements along dentine, which grows incrementally and archives intra- and interannual isotopic composition over the lifetime of the animal, would be useful for characterizing residency within and movements among water bodies with strong δ 18 O gradients, particularly between polar and lower latitudes, or between oceans and marginal basins. Spatial variation in marine oxygen isotope ratios ( δ 18 O) is potentially useful for characterizing marine mammal distributions and tracking movements across δ 18 O gradients. We measured δ 18 O values of dentine structural carbonate ( δ 18 O SC ) and phosphate ( δ 18 O P ) of odontocetes from regional marine water bodies spanning a range of surface water δ 18 O values and found strong correlations between dentine and marine surface water δ 18 O values. Results indicate sequential δ 18 O measurements along dentine, which grows incrementally and archives intra- and interannual isotopic composition over the lifetime of the animal, would be useful for characterizing residency within and movements among water bodies with strong δ 18 O gradients, particularly between polar and lower latitudes, or between oceans and marginal basins.

Description: [1]  Flooding land for water reservoir creation has many environmental impacts including the production of the greenhouse gases (GHG) carbon dioxide (CO 2 ) and methane (CH 4 ). To assess processes governing GHG emissions from the flooding of terrestrial carbon, three experimental reservoirs were constructed in upland boreal forest areas of differing carbon stores as part of the Flooded Upland Dynamics Experiment (FLUDEX). We calculated process-based GHG budgets for these reservoirs over five years following the onset of flooding. Stable isotopic budgets of carbon were necessary to separate community respiration ( CR ), which produces CO 2 , from net primary production ( NPP ), which consumes CO 2 , and to separate CH 4 production from CH 4 consumption via oxidation. NPP removed up to 44% of the CO 2 produced from CR . CR and NPP exhibited different year-after-year trends. CH 4 flux to the atmosphere increased about 2-fold over three years, yet isotopic budgets showed CH 4 production in flooded soils increased nearly 10-fold. CH 4 oxidation near the flooded soil–water interface greatly decreased the CH 4 flux from the water column to the atmosphere. Ebullition was the most important conduit of CH 4 to the atmosphere after three years. Although CH 4 production increased with time, the total GHG flux, in CO 2 equivalents, declined. Contrary to expectations, neither CR nor total GHG fluxes were directly related to the quantity of organic carbon flooded. Instead, these reservoirs produced a strikingly similar amount of CO 2 equivalents over five years.

Description: Although predators influence behavior of prey, analyses of electronic tracking data in marine environments rarely consider how predators affect the behavior of tracked animals. We collected an unprecedented dataset by synchronously tracking predator (killer whales, N = 1; representing a family group) and prey (narwhal, N = 7) via satellite...

Description: Surface locomotory trace fossils from the Mistaken Point Formation of Newfoundland, dated at ~ 565 Ma, suggest that organisms capable of controlled locomotion and possessing muscular tissue may have existed among Avalonian Ediacaran macrofossil assemblages. Here we describe the Mistaken Point trace-fossil assemblage in full, discuss its stratigraphic context within the Mistaken Point Formation, and explore the competing hypotheses for the formation of the traces. We find that the trace fossils, preserved within a turbidite succession in a deep-marine depositional environment, are not attributable to abiogenic structures, to Ediacaran tubular or filamentous body fossils, to rangeomorph stems, or to a host of late Ediacaran and early Phanerozoic ichnofossils. Specimens within the assemblage show some similarities to the ichnogenera Helminthoidichnites and Archaeonassa , but discrepancies in certain aspects of their structure mean that we do not formally attribute them to these ichnotaxa at this time. The Mistaken Point ichnofossils possess morphological characteristics indicative of formation by an organism with a round base. Comparison with traces formed by modern organisms of such character appears to rule out formation by protistan, echinoderm, or annelid styles of movement, but is consistent with organisms moving via muscular controlled locomotion in a similar way to some modern mollusks and actinian cnidarians. We suggest therefore that the Mistaken Point trace-fossil assemblage reveals the presence of muscular metazoans in late Ediacaran deep-marine ecosystems. Such organisms cannot yet be attributed to specific phyla, but their inferred locomotory mechanisms share closest similarities with those utilized by extant actinians.

Description: A significant part of the intrinsic brightness variations in cool stars of low and intermediate mass arises from surface convection (seen as granulation) and acoustic oscillations (p-mode pulsations). The characteristics of these phenomena are largely determined by the stars’ surface gravity ( g ). Detailed photometric measurements of either signal can yield an accurate value of g . However, even with ultraprecise photometry from NASA’s Kepler mission, many stars are too faint for current methods or only moderate accuracy can be achieved in a limited range of stellar evolutionary stages. This means that many of the stars in the Kepler sample, including exoplanet hosts, are not sufficiently characterized to fully describe the sample and exoplanet properties. We present a novel way to measure surface gravities with accuracies of about 4%. Our technique exploits the tight relation between g and the characteristic time scale of the combined granulation and p-mode oscillation signal. It is applicable to all stars with a convective envelope, including active stars. It can measure g in stars for which no other analysis is now possible. Because it depends on the time scale (and no other properties) of the signal, our technique is largely independent of the type of measurement (for example, photometry or radial velocity measurements) and the calibration of the instrumentation used. However, the oscillation signal must be temporally resolved; thus, it cannot be applied to dwarf stars observed by Kepler in its long-cadence mode.