Analysis of morphological traits as a tool to identify the realized niche of phytoplankton populations: what do the shape of planktic microalgae, Anna Karenina and Vincent van Gogh have in common?

Understanding the dynamics of phytoplankton assemblages in various and variable aquatic ecosystems is of paramount importance, given the strategic supporting services offered by these organisms. Such knowledge is implicitly based on the analysis of the realized niche of the different populations, i.e. of the sets of conditions within which populations show a positive growth. The range of phytoplankton morphological traits variability is evolutionarily selected to maximize the ecological performance of species while they are entrained in the spectrum of turbulent flows. In addition, most phytoplankton species exhibit high morphological plasticity that can further optimize their performance under reduced environmental variability. Although this plasticity is well known, it is seldom considered in phytoplankton studies. Morphological analysis could therefore be used as a tool to estimate the environmental variability within which a species can persist and, ultimately, the niche width of phytoplankton populations. This opinion paper tries to answer the questions: to what extent can the morphological variability of phytoplankton offer a synthesis of the environmental variability of aquatic ecosystems?. Do the morphological traits contain sufficient information to describe the width of the realized niche of phytoplankton species? What can we do to fill eventual gaps in our knowledge

Trait-based ecology of microalgae

This paper introduces and summarises the main outcomes of the 19th workshop of the International Association for Phytoplankton Taxonomy and Ecology held in Tiszafured, Hungary, Tisza Balneum Hotel, from 23 to 30 September 2022. The selected theme of the workshop was "Trait-Based Approaches in Micro-Algal Ecology". The discussions presented during the workshop sessions resulted in the 18 articles contained in this Special Issue. There are 6 main thematic aspects developed by the participants: 1. Shape and size: are these traits easy to measure? 2. Spatial scales: when and where to look for microalgae? 3. Climate and extremes of ecological gradients: hot topics of this century. 4. Metaphyton and metaphytic habitats: life beyond plankton and benthos. 5. Microalgae in water management: phycology in practice. 6. Traditional and new methods: perspectives and comments. Trait-based approaches in microalgae ecology, although requiring further investigation and methodological development, represent a valid tool for refining the analysis of environmental variability in aquatic ecosystems. The papers presented in this Special Issue demonstrate that these approaches are extremely useful not only in the study of planktic algae but constitute a thoughtful method for the analysis of benthic and metaphytic microalgae in a wide variety of aquatic ecosystems

Preface: Trait-based approaches in micro-algal ecology

Non previst