Ecophysiological and morphological comparison of two populations of Chlainomonas sp. (Chlorophyta) causing red snow on ice-covered lakes in the High Tatras and Austrian Alps

Lenka Procházková,Daniel Remias,Andreas Holzinger,Tomáš Řezanka,Linda Nedbalová

doi:10.1080/09670262.2018.1426789

Abstract

ABSTRACTBased on analyses of multiple molecular markers (18S rDNA, ITS1, ITS2 rDNA, rbcL), an alga that causes red snow on the melting ice cover of a high-alpine lake in the High Tatras (Slovakia) was shown to be identical with Chlainomonas sp. growing in a similar habitat in the Tyrolean Alps (Austria). Both populations consisted mostly of smooth-walled quadriflagellates. They occurred in slush, and shared similar photosynthetic performances (photoinhibition above 1300 µmol photons m–2 s–1), very high levels of polyunsaturated fatty acids (PUFA, 64% and 74% respectively) and abundant astaxanthin accumulation, comparable to the red spores of Chlamydomonas nivalis (Bauer) Wille. Physiological differences between the Slovak and Austrian populations included higher levels of α-tocopherol and a 13Z-isomer of astaxanthin in the former. High accumulation of secondary pigments in the Slovak population probably reflected harsher environmental conditions, since the collection was made later in the growing season when cells were exposed to higher irradiance at the surface. Using a polyphasic approach, we compared Chlainomonas sp. with Chlamydomonas nivalis. The latter causes ʻconventionalʼ red snow, and shows high photophysiological plasticity, with high efficiency under low irradiance and no photoinhibition up to 2000 µmol photons m–2 s–1. Its PUFA content was significantly lower (50%). An annual cycle of lake-to-snow colonization by Chlainomonas sp. from slush layers deeper in the ice cover is proposed. Our results point to an ecologically highly specialized cryoflora species, whose global distribution is likely to be more widespread than previously assumed.

Highlights

Red snow discolouration in alpine and polar regions is caused by many algal species (Kol, 1968; Lutz et al, 2015; Matsuzaki et al, 2015), which in most cases belong to the genera Chlamydomonas, Chloromonas and Chlainomonas (Chlorophyta) (Novis et al, 2008; Brown et al, 2016; Procházková et al, 2018)
Red snow caused by Chlainomonas sp. was found in late spring 2016 on two still partly ice-covered high-alpine lakes, Ľadové Lake in the High Tatras and Gossenkӧlle Lake in the Tyrolean Alps (Table 1)
In the High Tatras, the lake was partly ice-free and red snow was visible on all remaining ice-covered parts (Figs 2–5)

Summary

Introduction

Red snow discolouration in alpine and polar regions is caused by many algal species (Kol, 1968; Lutz et al, 2015; Matsuzaki et al, 2015), which in most cases belong to the genera Chlamydomonas, Chloromonas and Chlainomonas (Chlorophyta) (Novis et al, 2008; Brown et al, 2016; Procházková et al, 2018). Two other species of this genus were described from snow, C. kolii (Hardy & Curl) Hoham and C. rubra (Stein & Brook) Hoham (Hoham, 1974a,b). Despite morphological similarities to spherical immotile red cells of the common snow alga Chlamydomonas nivalis, these two Chlamydo-monadacean genera are not closely phylogenetically related. Were restricted to summer snow banks with higher water content, whereas Chlamydomonas nivalis was not found in these specific habitats (Remias et al, 2016). The fatty acid profile has not been investigated for this genus so far

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