Benthic diatom communities in high altitude lakes: a large scale study in the French Alps

Abstract

-Altitude lakes are weakly impacted by human activities. This makes them choice ecosystems to understand how biological communities are impacted by natural factors. This question was addressed to littoral benthic diatoms, a largely used ecological indicator. We wanted to know if benthic diatoms in lakes are more impacted by local varying factors (altitude, lake depth...) or regional varying factors (geology). The study area takes place in the Northern French Alps. Littoral benthic diatoms of 63 natural lakes situated between 1350 and 2700 m · a.s.l. were sampled. Two categories of communities were observed: one of deep and lower altitude lakes and one of higher altitude and shallower lakes. In each category, communities were characterized and were corresponding to particular lake types: lakes dominated by a particular geology, lakes with a water level fluctuation, turbid lakes,... Communities did not show a spatial structure. We observed that local factors were more important than regional factors. Indeed, the study area displayed a mixed geology even at a local level. On another hand, altitude a local varying factor determines freezing period a determining item of high-altitude lake functioning.

Phylogenetic diversity and environment form assembly rules for Arctic diatom genera—A study on recent and ancient sedimentary DNA

“…Because HCO 3 − concentrations and spatial variables partly mirror vegetational changes across the sampled ecotone, we assume that additional environmental variables, such as vegetation type or related environmental variables that have not been exclusively considered in this study, contribute to the diatom community assembly. Geographic distance, however, seems to be of weaker influence, this has been shown in other alpine and boreal studies (Feret, Bouchez, & Rimet, ; Teittinen & Soininen, ) and has been demonstrated for the genus Staurosira across a similar area (Stoof‐Leichsenring et al, ) and for this study as well.…”

Lake-depth related pattern of genetic and morphological diatom diversity in boreal Lake Bolshoe Toko, Eastern Siberia

“…Alpha and beta diversity estimates based on morphological investigations have a negative correlation with water depth. A decreasing richness related to increasing water depth has been found in other morphologically based diatom studies: for example, within-lake analysis of water-depth variations in Canadian Worth Lake [67], within Lugu Lake, China [68], in Lake Ohrid in Southern Europe [11] and across a spatial dataset of alpine lakes with varying water depth [69]. In general, variations in water depth are related to differences in substrate [70] and correlate with water turbulence [71].…”

Peer Review #1 of "Critical multi-stranded approach for determining the ecological values of diatoms in unique aquatic ecosystems of anthropogenic origin (v0.1)"

“…Encyonopsis subminuta is regarded as a cosmopolitan taxon, occurring in the temperate and boreal zone. It is most abundant in oligo-to mesotrophic waters with electrolytic conductivity between 190-250 µS cm -1 (Krammer 1997;Noga et al 2014;Novais et al 2014;Feret, Bouchez & Rimet 2017). Encyonopsis subminuta may be sensitive to the concentration of Fe ions; however, the increase of these ions is associated with a drop in pH.…”