Annual Cycle of Mat‐Forming Filamentous Alga Tribonema cf. minus (Stramenopiles, Xanthophyceae) in Hydro‐Terrestrial Habitats in the High Arctic Revealed By Multiparameter Fluorescent Staining

Abstract

The filamentous microalga Tribonema sp. (Stramenopiles, Xanthophyceae) plays an important role in shallow water polar (streams and seepages) and seasonally cold habitats in temperate regions (ponds). In these habitats, freezing and desiccation, and thus freeze–thawing and drying–rewetting cycles, are frequent. These regions produce visible biomass and are important components of low temperature‐adapted communities. We characterized the annual cycles of a Tribonema cf. minus population in two habitats (seepage and stream) in the High Arctic, Svalbard. Seasonality, locality, and their combination (particularly changing environmental conditions) together with cultivation conditions of strains significantly affected their morphological characteristics. Morphological changes following hardening processes related to preparation for the winter period (transition from vegetative cells to akinete and/or pre‐akinete) were recorded. Over the year, positive water temperatures (warmest 13.3°C) occurred for 5 months while negative (lowest temperature was –17.4°C) lasted for 7 months. In winter, there were two melt periods. Vitality staining protocol showed a high number of viable (77.4% and 53.8%) and dormant cells (1.7% and 4.1%; capable of growth and reproduction once suitable conditions return) in the winter seepage and stream, respectively. NPQ and OJIP chlorophyll fluorescence parameters revealed several hours recovery of photosynthesis (both field and control samples). During recovery, only minor or mild stress on photosynthesis was detected. FV/FM values (the photosynthetic efficiency of photosystem II in a dark‐adapted state) in all field and control samples varied around 0.4. Tribonema cf. minus is capable of surviving winter Arctic conditions (perennial strategy).

Winter survival of the unicellular green alga Micrasterias denticulata: insights from field monitoring and simulation experiments

“…Open circles mark outlier values between 1.5 and 3 times of the IQR herbaceous species that outlast in always warmer soil. While the strategy of Micrasterias is to escape, other algae have proven to achieve considerable freezing tolerance in winter (Elster et al 2008;Hawes 1990;Jimel et al 2020;Trumhova et al 2019).…”

A critical review of soil algae as a crucial soil biological component of high ecological and economic significance

“…In general, algae of aero‐terrestrial habitats include many specific groups of algae. Accordingly, the literature on algal diversity of aero‐terrestrial habitats may be categorized into that of the Cyanobacteria (Kumar & Adhikary, 2015; Lemes‐da‐Silva et al., 2010; Pushkareva et al., 2018), Chlorophyta (Ray & Thomas, 2012; Vijayan & Ray, 2015), Bacillariophyta (Zhang et al., 2020), Streptophyta (Mikhailyuk et al., 2018), Xanthophyceae (Jimel et al., 2021; Rybalka et al., 2020), Eustigmatophyceae (Flechtner et al., 2013; Trzcińska et al., 2014), and Euglenophyceae (Adesalu & Olugbemi, 2015; Lin et al., 2013).…”