Improving Taxonomic Bias using iNaturalist Records on Helgoland

Citizen science platforms such as iNaturalist provide valuable opportunities for large-scale biodiversity monitoring but are prone to taxonomic biases, favoring charismatic and easily observable species while underrepresenting less visible taxa, particularly marine invertebrates. This study investigates the potential for student-led field courses to mitigate these biases by contributing observations from Helgoland, a small German island in the North Sea. We analyzed iNaturalist data from Helgoland since 2008 and compared it with marine species observations collected by two cohorts of Humboldt Universität students in 2023 and 2025. We uploaded over 350 marine species to iNaturalist, including 16 new phyla and 24 new classes previously absent from the platform for this locality. While student observations reflected some existing taxonomic biases toward more conspicuous groups, they substantially increased overall taxonomic coverage, particularly for otherwise inaccessible or microscopic taxa. This indicates that accessibility and resources are major contributors to bias in citizen science. Overall, our findings show that structured student engagement can meaningfully expand and enrich citizen science biodiversity data, complementing professional research and supporting more comprehensive monitoring of underrepresented taxa.