Diatom communities in Petuniabukta (Spitsbergen, Svalbard Archipelago): a taxonomic and (paleo)ecological approach

Diatoms are one of the most abundant algal groups in polar ecosystems, both in number of specimens as in number of species. Their characteristic silica valve and the significant responses to changes in their physical and chemical environment, make them excellent bio-indicators used in applied environmental and paleoecological studies. Despite this, the species composition and ecological preferences of High Arctic diatom communities are poorly known, mainly due to historic force-fitting and incorrect species identifications. The diatom flora of Svalbard in particular is little studied and most studies published so far are very concise. Here we studied the freshwater littoral diatom flora of Petuniabukta (Spitsbergen) on a spatial and temporal scale in order to reduce the taxonomic and ecological uncertainty when applying diatoms as (paleo)environmental indicators in the Arctic.For the spatial scale, the diatom flora of 53 freshwater lakes was analysed using light and scanning electron microscopy. More than 300 taxa belonging to 59 genera have been found, of which one third could not be identified below genus level. Two new species, Gomphonema svalbardense and Achnanthidium petuniabuktianum, have recently been described as new to science and several other taxa are in need of a formal description. Cluster and ordination analyses allowed separating the diatom communities in four main assemblages which were explained by differences in environmental characteristics, such as the presence of streams, mosses and glaciers.For the temporal scale, the diatom succession in a ~6000 year old sediment core from Garmaksla Lake was studied. Changes in the relative abundances of the two dominating taxa, Staurosira venter and Amphora affinis, suggest subsequent periods of warming and cooling. Unprecedented changes in the top layers of the core are attributed to climate warming as result of the end of the Little Ice Age, ~100–150 years ago, and, more recently, human induced environmental changes.In conclusion, the high number of unidentified taxa in this study indicates that a profound revision of the Arctic diatom flora is highly desired, not only to improve our fundamental knowledge concerning the diversity, ecology and biogeography of Arctic diatoms, but also to advance applied (paleo)ecological studies.

Jaar van publicatie:2016