Diatomee

Diatom communities in the High Arctic aquatic habitats of the Svalbard Islands

Dinah

Some of the most prominent signs of climate change can be observed in the Arctic region. Recent studies, however, show that the effects of climate change may be different from previously thought and that the cascading effects associated with it will be manifested in complex ways in different parts of the world. Improved knowledge of the multiple and interacting effects of such changes on both abiotic and biotic elements of various ecosystems will be essential in the prediction of future shifts in global biodiversity and Earth’s biogeochemical cycles. It is necessary to gather detailed information on a variety of habitats that are already or may soon be experiencing such changes. Studies have started to focus on the Arctic region. Nevertheless, relatively limited information is available on the ecology of many Arctic aquatic habitats, especially those located in the High Arctic. These habitats offer a unique opportunity to study the multifactorial impacts of climate change on selected groups of organisms, while studies conducted in remote Arctic regions may be particularly useful and valuable for the assessment and better understanding of the potential consequences of climate change. Enhanced warming of high latitude regions relative to the global average (known as ‘‘polar amplification’’) is a commonly accepted notion, but the limited length of the instrumental data record is a serious obstacle to addressing many crucial questions regarding environmental and climatic changes over the longer term. Other tools and approaches are applied in investigations of ecosystem change over time. Arctic lake and pond sediments, for instance, are considered natural recorders of temporal variations as they may contain various indicators of past and present physical, chemical and biological conditions. Among such indicators, diatoms are the most commonly used thanks to their high sensitivity and quantifiable optima to numerous environmental variables. Information on diatoms from Svalbard (High Arctic) aquatic habitats is at best fragmentary, and little is yet known about their contemporary communities in terms of either taxonomic composition or ecological preferences. The ‘‘calibration’’ of modern diatom assemblages to presentday conditions is necessary to enable inferences to be drawn on past or future environmental changes. We will investigate and describe the diatom assemblages of different aquatic habitats in northern Spitsbergen in relation to their environment. The survey will include shallow coastal areas, ponds and lakes, aquatic and terrestrial mosses (which provide favourable habitat for diatoms) and the glacier surfaces (cryoconit holes). We focus on the examination of (1) the diatom biogeographic patterns, (2) diatom dispersal processes, (3) environmental controls that shift the community composition and distribution, and possibly arising from that (4) contribution to understanding of past, present, and future global environmental changes. The proposed project will address the major shortcomings in the scientific literature concerning Arctic diatoms, their relationships and interactions with surrounding microenvironment, their identification, consistent application of taxonomic distinctions, and any understanding of their distribution in the modern system that then might be applied to the paleorecords or an efficient environmental monitoring system. Brief research plan Samples of Arctic diatoms from 1) surface sediments of shallow costal regions, 2) surface sediments of ponds and lakes, 3) aquatic and terrestrial mosses, 4) cryoconite holes, will be collected from remote sites located in Svabard to assure a high number of diverse habitats to be studied. Immediately after collection, material will be placed in separate plastic tubes or bags and preserved with Logol’s solution or airdried. To minimize the footprint and to maximize the environmental background information to be obtained during the expedition, material will be collected at all accessible sampling sites already selected by other research teams involved in the expedition. To ensure the most accurate and informative taxonomic data, samples will be cleaned and prepared for detailed examination of the diatom frustule ultrastructure using both light and scanning electron microscopy following standard protocols. The diatom identification will be based on extensive reviews, comparison with the most up-to-date publications and holotypes from the available diatom collections, and consultation swith national and international world-leading diatom taxonomists. We expect to reveal multiscale distribution patterns of diatoms related to various aspects, e.g. local processes and regional patterns, habitat heterogeneity, environmental gradients, habitat alteration processes etc. These results synthesized with all data gathered in the course of the expedition will improve our understanding of Arctic ecosystems, how they change, how they are threatened by human activities and how they can provide insights into past and future environmental and climate changes and fundamental ecological questions.

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