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As part of a collaborative project between BAS, DRDC Suffield (Canada) and ITRES Research Ltd., (Canada) the first known airborne hyperspectral dataset was acquired over the Antarctic in February 2011. The simultaneous deployment of commercially available visible-near infrared and shortwave infrared spectrometers generated a dataset covering 0.35 to 2.5 µm spectral range at a spectral resolution of 9.6-14 nm. To enable quantitative analysis of surface properties using imaging spectrometry data the removal of atmospheric absorption and scattering effects is an essential pre-processing step. The implementation of a sufficiently accurate and robust atmospheric correction methodology is of critical importance in ensuring that the results from spectral and spatial analysis algorithms are as accurate as possible. However, whilst methodologies are well established for most environments, there is currently no published methodology for correcting airborne hyperspectral data in the Antarctic region. This study presents initial results from an investigation into the applicability of the MODTRAN-5® radiative transfer model and the ATCOR-4 atmospheric correction package for producing atmospherically corrected hyperspectral data in the unique Antarctic environment; an environment that is cold, dry and has low levels of aerosols and atmospheric pollution. Initial results from radiative transfer modelling and atmospheric correction produce absolute reflectance spectra which are partially comparable to laboratory measured spectra. Improvements are seen with the hybrid approach of radiative transfer modelling and the empirical line method using in-scene ground targets. Residual noise remains present due to absorption by atmospheric gases and aerosols which are not appropriately modelled for this environment. Overall, this demonstrates that commercially available packages are not currently flexible enough to correct Antarctic hyperspectral data without the addition of in-scene ground calibration targets. The implementation of Antarctic aerosol and atmospheric profiles into the radiative transfer model would likely improve these corrections and remains an area of investigation for future hyperspectral campaigns in the region.

Sensory systems provide critical filters that enable organisms to detect and recognize valuable resources. Trophic cascades, structuring populations and communities, are determined to a large degree by trait-mediated interactions that rely on sensory inputs. Certain molecules serve as chemosensory stimuli and play keystone roles in determining outcomes of predator-prey dynamics at multiple trophic levels. Here, a surface-adsorbed glycoprotein signal molecule, MULTIFUNCin, is fully identified and its role in waveswept rocky intertidal community dynamics investigated. Barnacles (Balanus glandula), are constrained to produce MULTIFUNCin for cuticle/shell formation. This compound evoked settlement by conspecifics larvae in field assays, and thus, operates as seminal cue for recruitment. Moreover, the same substances triggered predation by a numerically dominant whelk species (Acanthinucella spirata) on barnacle juveniles and adults in lab and field experiments. This glycoprotein, therefore, balances simultaneous demographic processes that enhance, and diminish, barnacle populations. As dominant competitors for space, the relative equilibrium between barnacle recruitment and predation mortality has strong, cascading direct and indirect effects on community dynamics. Hence, MULTIFUNCin plays a keystone role within rocky intertidal habitats.

Rare earth elements (REEs) generate characteristic absorption features in visible to shortwave infrared (VNIRSWIR) reflectance spectra. Neodymium (Nd) has among the most prominent absorption features of the REEs and thus represents a key pathfinder element for the REEs as a whole. Given that the world's largest REE deposits are associated with carbonatites, we present spectral, petrographic, and geochemical data from a predominantly carbonatitic suite of rocks that we use to assess the feasibility of imaging REE deposits using remote sensing. Samples were selected to cover a wide range of extents and styles of REE mineralization, and encompass calcio-, ferro-and magnesio-carbonatites. REE ores from the Bayan Obo (China) and Mountain Pass (United States) mines, as well as REE-rich alkaline rocks from the Motzfeldt and Ilímaussaq intrusions in Greenland, were also included in the sample suite. The depth and area of Nd absorption features in spectra collected under laboratory conditions correlate positively with the Nd content of whole-rock samples. The wavelength of Nd absorption features is predominantly independent of sample lithology and mineralogy. Correlations are most reliable for the two absorption features centered at ∼744 and ∼802 nm that can be observed in samples containing as little as ∼1,000 ppm Nd. By convolving laboratory spectra to the spectral response functions of a variety of remote sensing instruments we demonstrate that hyperspectral instruments with capabilities equivalent to the operational Airborne Visible-Infrared Imaging Spectrometer (AVIRIS) and planned Environmental Mapping and Analysis Program (EnMAP) systems have the spectral resolutions necessary to detect Nd absorption features, especially in high-grade samples with economically relevant REE accumulations (Nd> 30,000 ppm). Adding synthetic noise to convolved spectra indicates that correlations between Nd absorption area and whole-rock Nd content only remain robust when spectra have signal-to-noise ratios in excess of ∼250:1. Although atmospheric interferences are modest across the wavelength intervals relevant for Nd detection, most REE-rich outcrops are too small to be detectable using satellite-based platforms with>30-m spatial resolutions. However, our results indicate that Nd absorption features should be identifiable in high-quality, airborne, hyperspectral datasets collected at meter-scale spatial resolutions. Future deployment of hyperspec-tral instruments on unmanned aerial vehicles could enable REE grade to be mapped at the centimeter scale across whole deposits.