Ecology and photosynthetic activity of a newly-discovered Vaucheria sp. dominated Arctic microphytobenthos, Svalbard

A comprehensive study of the ecology and photosynthetic activity of a newlydiscovered Vaucheria sp. dominated arctic microphytobenthos was addressed here. The microphytobenthos is a very diversified community of microscopic organisms from the surficial sediment of aquatic ecosystems. It typically consists of various assemblages of substrate-dwelling photosynthetic diatoms, cyanobacteria, flagellates and algae. The microphytobenthos plays a central ecological role in estuarine environment, responsible for a significant fraction of the total primary production, mediating water-sediment nutrient exchanges, enhancing benthic-pelagic coupling and efficiently stabilizing the sediment. Despite their ecological value in coastal areas, very little is known about arctic microphytobenthos ecology and photosynthetic performances. Across the arctic coastline, where large inter-seasonal variations in light, temperatures and nutrient levels are experienced along with increasing pressures, microbenthic communities have shown signs of excellent metabolic adaptations. In case, across this arctic tidal flat, Vaucheria sp. was found to show a remarkable adaptation to the local ecological parameters. We demonstrated in this ecosystem the strong impacts of both marine and freshwater co-occurrences creating Vaucheria sp. environment. The heterogeneity of Vaucheria sp. habitat was described. Locally, the water column was phosphorus-limited and a temporal shift from phosphorous to silica-limited conditions occurred throughout the sampling period, witnessing of the highly dynamic nature of this tidal ecosystem. At the ecosystem level, the strong microphytobenthos’ photosynthesis was supported by significant high water-pH values, correlated to Vaucheria sp. spatial occurrence. Even though Vaucheria sp. seemed to dominate, we found evidences of a more complex micro-phytobenthic community functioning. Vaucheria sp. community exhibited adaptability to large variations in abiotic factors. Gasometric and Chlorophyll fluorescence measurements did not show any limitation of the photosynthetis over the range of environmental PAR suggesting good photoacclimation of Vaucheria sp. to arctic conditions. Based on the compensation irradiance value of Vaucheria sp. we demonstrated this alga to be low-light adapted. Furthermore, Vaucheria sp. was capable of fast photo-acclimation through the consecutive transition from low to high incoming light irradiances. This quality of Vaucheria sp. fast photo-acclimation is thought to be linked to state transitions or effective xanthophyll cycle.Um estudo abrangente da ecologia e atividade fotossintética de uma espécie recémdescoberta no Ártico, Vaucheria sp., que domina o microfibentos foi abordado neste estudo. O microfitobentos é uma comunidade muito diversificada de organismos microscópicos localizada nos sedimentos superficiais dos ecossistemas aquáticos. Ocorre geralmente nos vários milímetros superiores de sedimentos iluminados, formando um subtil biofilme acastanhado ou esverdeado no fundo do mar. O microfitobentos é constituído por vários grupos de diatomáceas fotossintéticas, cianobactérias, flagelados e algas. Esta comunidade fotossintética de microrganismos desempenha um papel ecológico central no ambiente estuarino. É responsável por uma fração significativa da produção primária total, podendo até exceder a produtividade pelágica em certas circunstâncias. Além disso, o microfitobentos desempenha um papel importante na mediação das trocas de nutrientes entre o sedimento e a água. Sabe-se também que melhora o acoplamento bento-pelágico e em algumas circunstâncias, afeta positivamente a bio estabilização do fundo do mar. Apesar da sua importância ecológica nas áreas costeiras, muito pouco se sabe sobre o microfitobentos ártico em relação à sua ecologia, desempenho fotossintético e produtividade. No litoral ártico, onde existem grandes variações inter-sazonais de luz, temperaturas e concentrações de nutrientes, juntamente com pressões crescentes, as comunidades microfitobênticas mostraram sinais de excelentes adaptações metabólicas. No estudo que foi realizado da planície de maré da costa ocidental de Svalbard em que habita a Vaucheria sp. foram encontrados bons desempenhos fotossintéticos. Demonstramos que neste ecossistema, existe um impacto forte das coocorrências marinhas e de água doce na qual a Vaucheria sp. habita. Sugere-se que a Vaucheria sp. pode tolerar uma grande variedade de conteúdo de salinidade até aproximadamente 40 PSU. A heterogeneidade ecológica desta planície de maré em que Vaucheria sp. ocorre foi descrita cuidadosamente. Através da amostragem da coluna de água, observou-se que o fósforo era um fator limitante. No entanto, no final de agosto de 2017, observou-se uma alteração temporal que afetou os níveis de nutrientes na coluna de água. Observou-se que ao alterar as condições, alterando o fósforo como fator limitante para sílica, observou-se a natureza altamente dinâmica desse ecossistema de maré e sugerindo uma transição na comunidade estuarina. Especula-se que o florescimento tardio de diatomáceas árticas no verão, deve-se a uma exaustão significativa de sílica na coluna de água, sendo responsável por esta mudança de nutrientes no final da amostragem. Outros compostos químicos foram relatados como variar significativamente ao longo da amostragem. Notavelmente, na coluna de água registou-se uma diminuição significativa no NO2-N, enquanto que no Azoto total, PO4-P, Fósforo Total, Mg, SO4, K, Na e Ca observou-se um aumento significativo. Da mesma forma, observou-se uma diminuição significativa nas concentrações de NO3-N e PO4-P no sedimento da planície de maré. Em relação ao ecossistema, demonstrou-se que existe uma forte contribuição da Vaucheria sp. para a produtividade fotossintética local, afetando o ciclo de carbonatos na coluna de água. Portanto, esta comunidade de Vaucheria sp. afeta significativamente os fatores químicos da água, especialmente o ciclo de carbonato. O microfitobentos não afeta apenas os fatores hidroquímicos da planície de maré, afeta também as características físicas e químicas do sedimento. A comunidade de Vaucheria sp. está correlacionada com baixo teor de unidade sedimentar e baixa percentagem de carbono orgânico nos sedimentos da planície de maré. Essa observação pode indicar o forte impacto dessa comunidade microfitobêntica na biogeoquímica do leito marinho. Um efeito que foi estudado e que é bem conhecido dos microfitobentos no sedimento é a bio estabilização do fundo do mar. Os organismos microfitobentónicos desempenham um papel fundamental no aumento da estabilização de sedimentos, protegendo o leito marinho da erosão causada pelo constante movimento da maré, libertando substâncias poliméricas extracelulares resultantes da atividade fotossintética, auxiliando na-bio estabilização do leito marinho. Embora não se tenha investigado diretamente a estabilidade do sedimento, especula-se que as observações ecológicas podem ser uma consequência indireta da bio-estabilização local do sedimento induzido pela comunidade de Vaucheria sp.. Outras investigações seriam necessárias para confirmar o hipotético efeito bio-estabilizante desta comunidade no ecossistema. Embora Vaucheria sp. pareça dominar este ecossistema de maré baixa, foram encontradas evidências da ocorrência de uma comunidade microfitobêntica muito mais dinâmica e complexa e na qual Vaucheria sp. parece desempenhar uma função essencial. A comunidade de Vaucheria sp. exibiu uma notável plasticidade fisiológica em relação a um amplo espectro de intensidades luminosas que variam de 10 a 650 μmol m-2 s-1. A combinação de técnicas gasométricas e de várias técnicas de fluorescência de clorofila a foram utilizadas neste estudo, permitindo determinar os desempenhos fotossintéticas gerais da comunidade de Vaucheria sp. A comunidade de Vaucheria sp. foi capaz de utilizar um amplo espectro de intensidades PAR sem mostrar qualquer fotoinibição para intensidades PAR até um máximo de 650 μmol m-2 s-1. Foram medidas características fotossintéticas gerais das Vaucheria sp. e, foi reportado nesta espécie uma eficiência fotossintética média (α) de 0,00641 (± 0,00061), a qual não se alterou com a intensidade PAR a que foi aclimatada. A fotossíntese máxima (Pmax) variou de 0,756 a 1,188 nmol g-1 s-1, medida por via gasométrica. O Icomp médio foi de 38,53 μmol m-2 s-1, aproximadamente dez vezes menor do que o das algas bentónicas análogas extremamente sombreadas. Além disso, dados os valores de irradiância de saturação, Ek ou Isat, Vaucheria sp. parece estar adaptada à pouca luz. Por fim, Vaucheria sp. foi capaz de uma fotoaclimatação rápida através da transição consecutiva entre a luz de baixa irradiância recebida e a de alta. Esta qualidade de fotoaclimação rápida de Vaucheria sp. está provavelmente ligada às transições de estado ou ao ciclo das xantofilas.This work was supported by the University of South Bohemia (USB), Faculty of Science, Centre for Polar Ecology (projects LM2015075, EF16_013/0001782 – SoWa Ecosystems Research)

Forging a maritime alliance: Norway and the evolution of american maritime strategy 1945-1960

The study examines the development of American maritime interests in the High North in the period from 1945 to 1960 with particular emphasis on the Eisenhower period and Admiral Arleigh Burke's tenure as Chief of Naval Operations. Specifically, it traces the reorientation of US concern about Soviet naval developments from the Baltic area to the Northern Fleet area after 1955. It explores how, in the latter half of the 1950s, Norway acquired a central role in US defence strategy as the US Navy - partly in response to the weakening of British naval power - moved into the Northeast Atlantic. By 1960 Norway was providing navgational support for the first generation of US nuclear-fuelled ballistic missile submarines and was playing a key part in the nuclear-oriented anti-submarine strategy of the US Navy. In 1960 the process which had begun in the late 1940s when the US increasingly came to assume Britain's traditional role as Norway's principal source of external support had been largely completed

Shipwreck at Cape Flora

Benjamin Leigh Smith discovered and named dozens of islands in the Arctic but published no account of his pioneering explorations. He refused public accolades and sent stand-ins to deliver the results of his work to scientific societies. Yet, the Royal Geographic Society's Sir Clements R. Markham referred to him as a polar explorer of the first rank. Traveling to the Arctic islands that Leigh Smith explored and crisscrossing England to uncover unpublished journals, diaries, and photographs, archaeologist and writer P. J. Capelotti details Leigh Smith's five major Arctic expeditions and places them within the context of the great polar explorations in the nineteenth century

The Arctic Game

Since outsiders first visited the Arctic, they have believed in man\u27s ability to conquer the region. Today\u27s Arctic conquest is not one of heroic exploration, but rather one of ownership and exploitation. This paper illustrates contestation in the Arctic through the metaphor of a game, with attendant prizes, players, and rules. It focuses on how to prevent the future destruction of the Arctic given the interactions of the Arctic\u27s landscape, prizes, players, and current management frameworks. In the wake of renewed resource exploitation and escalating climate change impacts, the current frameworks and mindsets are inadequate to support the precarious balance of cooperation and competition in the region. The presence of an indigenous population is a defining characteristic of the Arctic landscape, requiring a change from traditional policy methods as an appropriate management tool. Turning toward leadership from northern indigenous populations and following the example of cooperation initiated by the natural science community may be the best way forward to prevent a dystopian future for the Arctic

Microbial genomics amidst the Arctic crisis

The Arctic is warming – fast. Microbes in the Arctic play pivotal roles in feedbacks that magnify the impacts of Arctic change. Understanding the genome evolution, diversity and dynamics of Arctic microbes can provide insights relevant for both fundamental microbiology and interdisciplinary Arctic science. Within this synthesis, we highlight four key areas where genomic insights to the microbial dimensions of Arctic change are urgently required: the changing Arctic Ocean, greenhouse gas release from the thawing permafrost, 'biological darkening' of glacial surfaces, and human activities within the Arctic. Furthermore, we identify four principal challenges that provide opportunities for timely innovation in Arctic microbial genomics. These range from insufficient genomic data to develop unifying concepts or model organisms for Arctic microbiology to challenges in gaining authentic insights to the structure and function of low-biomass microbiota and integration of data on the causes and consequences of microbial feedbacks across scales. We contend that our insights to date on the genomics of Arctic microbes are limited in these key areas, and we identify priorities and new ways of working to help ensure microbial genomics is in the vanguard of the scientific response to the Arctic crisis

Fine-grained quartz from cryoconite holes of the Russell Glacier, southwest Greenland – a scanning electron microscopy study

Funding Information: Prof. Albertas Bitinas (Klaipėda) and Prof. Petras Šinkūnas (Vilnius) are thanked for valuable comments, which improve the final version of the manuscript. Research was supported by the SIA SunGIS (E. Kalińska-Nartiša), by the ERAF project No. 1.1.1.2/ VIAA/1/16/118 (K. Lamsters) and by University of Latvia project “Climate change and sustainable use of natural resources” (No. AAP2016/B041).We thank Reinis Pāvils for field assistance. Publisher Copyright: © Baltica 2017.The western ablation zone of the Greenland ice sheet is darker than the surrounding ice, because a higher amount of fine-grained particles, known as a cryoconite, occur. To date, biotic cryoconite components have gained a lot of attention, in contrast with mineral components, which have been studied to a limited extent. In this study, fine-grained quartz grains from the cryoconite holes of the Russell Glacier, southwest Greenland are, therefore, examined. Authors use scanning electron microscope to elucidate shape, surface character and origin of these mineral quartz particles. Triangular-faceted, sharp-edged grains dominate in most of the investigated samples, and originate from local sources, where grain-to-grain contact in the ice prevail. Grains with smooth corners and edges result from chemical weathering in meltwater of alkaline pH, in which quartz solubility significantly increases. However, part of these rounded grains is due to mechanical abrasion by wind action. Postsedimentary frost action is visible through grains entirely or partially covered by scaly-grained encrustation. Local processes and sources are largely responsible for aforementioned grain outlines. However, few grains with bulbous silica precipitation argue for a dry and warm climate, and distant, out-of-Greenland origin.publishersversionPeer reviewe

Benthic microalgal production in the Arctic: Applied methods and status of the current database

The current database on benthic microalgal production in Arctic waters comprises 10 peer-reviewed and three unpublished studies. Here, we compile and discuss these datasets, along with the applied measurement approaches used. The latter is essential for robust comparative analysis and to clarify the often very confusing terminology in the existing literature. Our compilation demonstrates that i) benthic microalgae contribute significantly to coastal ecosystem production in the Arctic, and ii) benthic microalgal production on average exceeds pelagic productivity by a factor of 1.5 for water depths down to 30 m. We have established relationships between irradiance, water depth and benthic microalgal productivity that can be used to extrapolate results from quantitative experimental studies to the entire Arctic region. Two different approaches estimated that current benthic microalgal production in the Arctic is between 1.1 and 1.6×107 tons C year-1. Climate change is expected to increase the overall primary production and affect the balance between pelagic and benthic productivity in the Arctic. It is therefore imperative to get better quantitative understanding of the relationship between increased freshwater run-off, shrinking sea-ice cover, light availability and benthic primary production to assess future impact on the Arctic food web and trophic coupling. © 2009 by Walter de Gruyter