Landscape-driven environmental variability largely determines abiotic characteristics and phytoplankton patterns in peat bog pools (Tierra del Fuego, Argentina)

AbstractPeat bog pools around Tamsweg (Lungau, Austria) are typical habitats of the unicellular green alga Micrasterias denticulata. By measurement of water temperature and irradiation throughout a 1-year period (2018/2019), it was intended to assess the natural environmental strain in winter. Freezing resistance of Micrasterias cells and their ability to frost harden and become tolerant to ice encasement were determined after natural hardening and exposure to a cold acclimation treatment that simulated the natural temperature decrease in autumn. Transmission electron microscopy (TEM) was performed in laboratory-cultivated cells, after artificial cold acclimation treatment and in cells collected from field. Throughout winter, the peat bog pools inhabited by Micrasterias remained unfrozen. Despite air temperature minima down to −17.3 °C, the water temperature was mostly close to +0.8 °C. The alga was unable to frost harden, and upon ice encasement, the cells showed successive frost damage. Despite an unchanged freezing stress tolerance, significant ultrastructural changes were observed in field-sampled cells and in response to the artificial cold acclimation treatment: organelles such as the endoplasmic reticulum and thylakoids of the chloroplast showed distinct membrane bloating. Still, in the field samples, the Golgi apparatus appeared in an impeccable condition, and multivesicular bodies were less frequently observed suggesting a lower overall stress strain. The observed ultrastructural changes in winter and after cold acclimation are interpreted as cytological adjustments to winter or a resting state but are not related to frost hardening as Micrasterias cells were unable to improve their freezing stress tolerance.

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Stauroneis fuegiana, a new Stauroneis species (Bacillariophyta) from Tierra del Fuego, southern Argentina

Phytotaxa ◽

10.11646/phytotaxa.311.1.8 ◽

2017 ◽

Vol 311 (1) ◽

pp. 85

Author(s):

VALERIA CASA ◽

GABRIELA MATALONI ◽

BART VAN DE VIJVER

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Central Area ◽

Taxonomic Position ◽

Tierra Del Fuego ◽

Peat Bog ◽

New Taxon ◽

Diatom Flora ◽

Scanning Electron

During a survey of the freshwater aquatic diatom flora of two peat bog areas in Tierra del Fuego, southern Argentina, a new taxon belonging to the genus Stauroneis that could not be identified was observed. Based on detailed light and scanning electron microscopy observations and comparison with similar larger-celled Stauroneis species worldwide, the taxon is described as new: Stauroneis fuegiana Casa & Van de Vijver sp. nov. Stauroneis fuegiana can be distinguished based on the slightly raised marginal crest, the typical broadly lanceolate valve outline with subrostrate apices, the almost rectangular central area and its valve dimensions.Comments are made on its taxonomic position and how the new taxon can be distinguished from other larger-celled Stauroneis species. Brief notes on the ecology and distribution are added.

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Comprehensive Palaeobotanical Studies of Lacustrine-Peat Bog Sediments from the Mazovian/ Holsteinian Interglacial at the Site of Nowiny Żukowskie (Se Poland) – Preliminary Study

Bulletin of Geography Physical Geography Series ◽

10.2478/bgeo-2011-0002 ◽

2011 ◽

Vol 4 (1) ◽

pp. 21-45b ◽

Cited By ~ 2

Author(s):

Anna Hrynowiecka ◽

Artur Szymczyk

Keyword(s):

Aquatic Vegetation ◽

Environmental Variability ◽

Climatic Conditions ◽

Peat Bog ◽

Complete Disappearance ◽

Plant Macroremains ◽

Se Poland ◽

Carex Rostrata ◽

The Subject ◽

Betula Humilis

Abstract The environmental variability during the Mazovian/Holsteinian interglacial is better understood thanks to the results of multidisciplinary palaeobotanical studies. The perfectly preserved and abundant material from Nowiny Żukowskie in SE Poland has been the subject of numerous palaeobotanical analyses. The results both of initial pollen analysis and of the examination of plant macroremains provide a detailed view of changes in the palaeoenvironment of this area during the Mazovian/Holsteinian interglacial. Originally, the water basin was mostly the habitat of plants indicative of low trophy. The frequent occurence of swamp plants evidences a change in hydrological and climatic conditions consistent with the intra-interglacial climatic oscillation. In the subsequent part of the optimum, an expansion of swamps with Aracites interglacialis and Dulichium arundinaceum was recorded. The development of a peat bog overgrown by i.a. Sphagnum sp., Eriophorum vaginatum, and Andromeda polifolia was also observed. The growth of swamp and peat vegetation resulted in the nearly complete disappearance of aquatic vegetation, apart from species typical of the climatic optimum of the Mazovian/Holsteinian interglacial: Brasenia borysthenica and Aldrovanda dokturovskyi. The close of the interglacial was marked by the intensive development of peat bog and swamp communities with Carex rostrata, Menyanthes trifoliata, and A. interglacialis. The intensive increase in the number of A. interglacialis during the period described as the “birch oscillation” supports the hypothesis of noticeable changes in hydrological conditions at that time. The end of the described period is typified by a deterioration of climatic conditions, indicated by the increase in values for Betula humilis, B. nana, and Juniperus communis.

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