2024

Benito, Xavier; Passy, Sophia I.; Vilmi, Annika; Jamoneau, Aurélien; Tison-Rosebery, Juliette; Kahlert, Maria; Larson, Chad A.; Mruzek, Joseph L.; Soininen, Janne; Bramburger, Andrew

Recent research on diatom metacommunities has focused on disentangling the assembly mechanisms driving species and functional composition and biodiversity across space and time, including deterministic (environmental filtering and biotic interactions) and stochastic processes (dispersal and ecological drift). In this chapter, we provide an overview of this research and outline future directions. Environmental filtering and dispersal have received the most attention, while biotic interactions and ecological drift have remained comparatively understudied and require more investigations. We discuss diatom species and functional responses to major environmental factors, operating at local scales, including inorganic and organic acidity, conductivity, and limiting nutrients, and at regional scales, namely land use and climate. Research has shown that both high rates of dispersal (mass effects) and low rates of dispersal (limited dispersal) are responsible for species and guild composition. We recommend further observational but also experimental investigations on the relative importance of assembly mechanisms across spatial and temporal scales and along latitudinal, longitudinal, and elevational gradients. Global change with respect to climate, land use, and dissolved organic matter has been recognized as an important driver of diatom compositional and biodiversity shifts. However, further modeling work and building harmonized global diatom databases that encompass spatial and temporal observations as well as morphological and molecular data may be necessary to forecast possible diatom community and functional responses in the decades ahead.