Diversity and ecology of freshwater diatoms (Bacillariophyta) in Petuniabukta (Spitsbergen)

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 outer shell (the valve) and the significant responses to changes in their physical and chemical environment, make them excellent bio-indicators used in applied environmental, biogeographical and paleo-ecological studies. Unfortunately, our knowledge of the species composition of High Arctic diatom communities and their ecological preferences are only poorly known, mainly due to historic force-fitting and incorrect identifications of the composing species. The diatom flora of Svalbard in particular is only scarcely studied and most studies published so far are only quite summary. The present study attempts to contribute to our knowledge concerning the diversity and ecology of freshwater diatoms in the Petuniabukta region (Spitsbergen, Svalbard Archipelago). Samples of both epilithon and epiphyton of 40 lakes and pools were taken during the polar summer of 2013 and several physico-chemical lake characteristics (pH, conductivity and water temperature) were measured. The diatom communities were studied using light microscopy and, when appropriate, scanning elecktron microscopy. A total of 315 taxa belonging to 58 genera were observed. Of these, 239 taxa were identified up to the species, subspecies, variety or forma level. The identity of the other 76 taxa is uncertain or only known up to the genus level. At least 10 of the unidentified taxa can with certainty be considered new to science. A new Gomphonema species, Gomphonema svalbardense, has recently been described and several other taxa are currently being described which confirms that the diatom flora of Spitsbergen is not well known and many taxa remain to be discovered and described.Cluster analysis and ordination allowed separating the observed diatom communities in four different assemblages. Characterisation of these assemblages based on the measured physico-chemical features proved to be impossible indicating the probable importance of other environmental factors than measured in determining the diatom communities in the study area. Using literature data, it was possible to link the diatom assemblages with differences in environmental characteristics, e.g. presence of streams or currents, vegetation, glacial influence and sea spray.

Jaar van publicatie:2014