45 research outputs found

    Seasonal patterns and interannual variability of phytoplankton in Lake Stechlin

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    The paper presents results of detailed phytoplankton investigations in Lake Stechlin between 1994 and 2003. The analysis includes the picoplankton fraction (dominated by Cyanobium sp.) that regularly appears as a deep-layer chlorophyll maximum (DCM). Planktothrix and Aulacoseira are successful competitors against Cyanobium in the isothermal period, the consequences differ markedly due to the fact that Planktothrix is able and Aulacoseira is unable to accumulate in the DCM after the onset of thermocline. The „regular-Cyanobium” and „irregular-Planktothrix, -Aulacoseira” patterns of DCM development has a basic influence on ecosystem functioning. Lake Stechlin a pristine, oligo-mesotrophic deep lake, with an established and detailed monitoring system and thus has been an ideal reference site for studying the influence of global climate changes on plankton that may improve our predictive tools for impact assessment

    Phytoplankton

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    The Extremophile Endolithella mcmurdoensis gen. et sp. nov. (Trebouxiophyceae, Chlorellaceae), a new Chlorella-like Endolithic alga from Antarctica

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    The McMurdo Dry Valleys constitute the largest ice-free region of Antarctica and one of the most extreme deserts on Earth. Despite the low temperatures, dry and poor soils and katabatic winds, some microbes are able to take advantage of endolithic microenvironments, inhabiting the pore spaces of soil and constituting photosynthesis-based communities. We isolated a green microalga, Endolithella mcmurdoensis gen. et sp. nov, from an endolithic sandstone sample collected in the McMurdo Dry Valleys (Victoria Land, East Antarctica) during the K020 expedition, in January 2013. The single non-axenic isolate (E. mcmurdoensis LEGE Z-009) exhibits cup-shaped chloroplasts, electron-dense bodies, and polyphosphate granules but our analysis did not reveal any diagnostic morphological characters. On the basis of phylogenetic analysis of the 18S rRNA (SSU) gene, the isolate was found to represent a new genus within the family Chlorellaceae.We are sincerely grateful to Antarctica New Zealand for providing logistics support during K020 event. This campaign was conducted as part of the New Zealand Terrestrial Antarctic Biocomplexity Survey (nzTABS) through awards (UOWX0710 and UOWX1401) from the New Zealand Foundation for Research and Technology (FRST), Antarctica New Zealand, and the New Zealand Ministry of Business, Innovation and Employment to SCC. The work was also supported by the Portuguese Science and Technology Foundation (FCT) through grants UID/Multi/04423/2019 to CIIMAR, IF/01358/2014 and PTDC/MAR-BIO/2818/2012 to PNL, PTDC/CTA-AMB/30997/2017 to CM, and PhD scholarships to AR (SFRH/BD/140567/2018).info:eu-repo/semantics/publishedVersio

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