A roadmap to define and select aquatic biological traits at different scales of analysis

Abstract

Abstract Trait-based approaches are a powerful tool, as not only they improve the understanding on ecological complexity and functioning, but also allow the comparison across different ecosystems and biogeographic regions. They may be used to unveil ecosystem processes and assess community structures, but their great potential becomes limited when dealing with scattered trait data and its historically unstandardised trait nomenclature. The lack of standardisation allows for authors to use terminology of their preference, inevitably resulting in ambiguous misunderstandings and limiting the comparison between different studies. There have been a few attempts at organising trait vocabularies, but even these tend to be created following a single-ecosystem perspective, which limits their applicability. A systematic literature review was performed, where we identified and compiled 1127 traits across 37 datasets of fish, invertebrates and zooplankton from freshwater, marine and transition ecosystems. This dataset was then used to build on the Marine Species Traits Wiki and to propose a new unified approach for a trait vocabulary based directly on readily available trait data. We suggest one single standardised designation for all different traits identified, providing as well with a list of all different synonyms usually employed for these traits. A roadmap to help along the process of trait selection is also provided, offering a guide through four main steps and important questions for choosing an adequate set of traits at the beginning of any study, which constitutes one of the main challenges in functional ecology research. Overall, this proposal will provide a solid baseline for tackling gaps in trait nomenclature and ensuring a clearer future for functional ecology studies.