DNA metabarcoding reveals the responses of prokaryotes and eukaryotes microbiota to warming: are the patterns similar between taxonomic and trophic groups?

Abstract

The aquatic microbiota is involved in crucial ecosystem functions. Thus, investigating the effects of global warming on these organisms is highly relevant, especially given the numerous climatic changes expected by the end of the century. In this study, we used an experimental approach and high-throughput sequencing to evaluate the shortterm effect of warming predicted by different future scenarios in the composition of the planktonic freshwater bacteria and microeukaryotes, and to verify if the same effects occur for each trophic level separately (autotrophic, heterotrophic and mixotrophic). Our experiment demonstrated that the composition for eukaryotes and prokaryotes based on DNA metabarcoding is affected by the increase in temperature and these have a similar pattern of response to warming. This highlights the temperature importance in structuring the communities of different groups. Modifications in the communities were observed through the substitution of specific taxa, which occurred mainly in warmer levels. Changes in community composition were also identified when trophic levels were assessed separately. Mixotrophic eukaryotes organisms are more sensitive to warming, modifying the patterns of composition with an increase in temperature of 2 °C. Microeukaryotes and heterotrophic bacteria were more resistant, with alterations in the communities composition visualized only in higher warming levels. The composition of autotrophic organisms was not affected by the increase in water temperature in any of the biological classifications evaluated, although the richness of eukaryotic autotrophic has decreased with warming. Our results contribute to predict how different biological levels and trophic groups of the aquatic microbiota respond to global warming. This approach is relevant because warming leads to changes in community composition and affects ecosystem processes essentials to the aquatic environment.