Introducing fwtraits – an R package for obtaining freshwater biodiversity trait information

Species ecological parameters are crucial for understanding the functional responses to environmental perturbations, aiding in informing conservation strategies and formulating robust environmental policies. However, obtaining standardized species ecological parameters across various freshwater organism groups remains challenging for ecologists. The www.freshwaterecology.info database (hereafter referred to as “FWE”) provides an extensive repository of approximately 200 parameters, including biological traits, ecological preferences, and indicators for five freshwater organism groups: fishes, macroinvertebrates, macrophytes, phytoplankton, and phytobenthos. While the database represents an invaluable resource for ecological research, integrating these manifold parameters into analysis workflows still requires users to manually search, download, and organize data. This process is time-intensive and error-prone.To address these challenges, we present fwtraits, an R package that supports the integration of freshwater ecological parameters from FWE into analysis workflows. We demonstrate the package's usability by assessing the influence of climatic indicators on lotic fish species assemblages using community weighted means (CWMs). We selected four ecological parameters (habitat (rheophily), feeding habitat, feeding diet for adult fish, and temperature tolerance) and assessed spatial variation in these modalities across European river catchments. We observed high CWMs on less resilient modalities, such as stenothermal and rheophilic taxa (which thrive in fast-flowing waters) in the northern river basins. This enables the identification of critical habitats for threatened species, which in turn helps in conserving freshwater biodiversity. fwtraits can be used to access ecological parameters in a simple and reproducible way. To support users, we have integrated detailed vignettes—available on GitHub—that illustrate the data retrieval process for each of the five organism groups and integration in biogeographical analysis workflows.