ECOPHYSIOLOGIC AND TAXONOMIC REEVALUATION OF THREE CHLOROMONAS SPP. LIVING IN SNOW: COSMOPOLITAN SPECIES TURN OUT TO BE LOCAL ONES
Abstrakt
Melting snow fields in alpine and polar regions are inhabited by snow algae, causing discolouration of snow. In most cases these algae belong to the genera Chloromonas, Chlamydomonas and Chlainomonas.
Snow habitats were - 153 - colonised several times in the history by these flagellates. In the field, final life-cycle stages, a/planozygotes, are frequently found.
Attempts to cultivating them have usually failed since cells are prepared for survival in harsh conditions after complete snow melt. The objective of this study was to explore light requirements, morphology and phylogeny of snow algae thriving in the Tyrolean Alps (Austria), the Giant Mountains (Czech Republic) and the High Tatra Mountains (Slovakia, Poland).
The focus was on species of the genus Chloromonas, which causes green to orange and reddish snow. Surface cell wall ultrastructure was revealed by scanning light microscopy showing aplanozygotes with flanges or spikes, and thus affiliated with current morphologic descriptions of Chloromonas nivalis, Chloromonas rosae var. psychrophila and Chloromonas brevispina.
Localities above the timberline are also low light habitats, e.g. in deeper parts of the snowpack, at steep snow slopes in proximity to boulders, and thus are in this respect similar to habitats below the tree canopy. Comparison of the secondary structure prediction of the nuclear marker ITS2 rDNA with available sequences showed that the investigated algae represent several new species based on the compensatory- base change species concept.
In vivo chlorophyll fluorescence parameters were obtained with a pulse - amplitude modulated fluorometer. Aplanozygotes were physiologically active.
Photoinhibition was noticed from 100 to 200 μmol photons m-2 s-1 upward. Our results suggest that the biodiversity of snow algae in European mountain ranges is still underestimated.