Citizen science data can significantly improve predictions of potential ranges of non-charismatic species: a study on two freshwater sponges

Freshwater sponge species play crucial roles in aquatic ecosystems, yet their distribution patterns and responses to environmental changes remain insufficiently understood. Relying solely on platforms like GBIF for predicting species distribution may be inadequate and occasionally misleading due to biases and inaccuracies in the data. We investigated the distribution records and potential future distributions of two freshwater sponge species, Spongilla lacustris and Ephydatia fluviatilis, across Europe. Using various data sources, including the Global Biodiversity Information Facility (GBIF), literature records, and internet naturalist data (iEcology), we compiled a comprehensive dataset comprising 1,330 records for S. lacustris and 9,854 records for E. fluviatilis. While GBIF records predominated in Western Europe, additional sources filled gaps in distribution records, particularly in Central and Eastern Europe. Species distribution models (SDMs) performed well, with S. lacustris exhibiting a broad climatic optimum range in Western and Northern Europe, while E. fluviatilis displayed a narrower range, primarily in northern regions. Future projections indicated a northward shift of freshwater sponge species in response to climate change, with potential contractions in Baltic Sea countries. These findings underscore that using diverse data sources such as scientific literature, field surveys, local ecological knowledge, and citizen science initiatives offers a more holistic view of species distribution patterns. Social media platforms also play a significant role in supplementing biodiversity data and engaging communities in conservation efforts.