Large-scale geographical and environmental drivers of shallow lake diatom metacommunities across Europe

Abstract

Disentangling the relative role of species sorting and dispersal limitation in biological communities has become one of the main issues for community ecologists and biogeographers. In this study, we analysed a data set of epiphytic diatoms comprising 34 lakes from six European countries. This data set covers a relatively large latitudinal gradient to elucidate which processes are affecting the distribution of diatom communities on a broad spatial extent. Our results show strong environmental effects on the composition of the diatom communities, while the spatial factor effects were weak, emphasising that compositional variation was mainly due to species turnover. Our data support information from the literature that local abiotic factors are the main predictors controlling the compositional variation of diatom assemblages in European shallow lakes. More specifically, changes in species composition were driven mainly by nutrient content in Northern Europe, whereas lakes located in Southern Europe were more affected by conductivity and lake depth. Our results solve pending questions in the spatial ecology of diatoms by proving that species turnover is stronger than nestedness at any spatial scale, and give support to the use of epiphytic diatoms as biological indicators for shallow lakes.

We thank all the colleagues who contributed with any idea or support in this paper. We also thank Anne Mette Poulsen for her corrections on an earlier draft of the paper. This research was funded by the Consejería de Educación, Junta de Castilla y León, European Social Fund Youth Employment Initiative (EDU/1033/2017), and by the projects Metaponds, funded by the Spanish Ministry of Economy and Industry (project CGL2017-84176R), and ECOFRAME, funded by the EU. This paper is a homage to Prof. Brian Moss who was the coordinator of the ECOFRAME project and an inspiration to all of us.