Digital Comparative Taxonomic Analysis of Diatom Communities for Drowning Site Identification

BACKGROUND: The determination of the drowning site in forensic medicine is based on the comparative analysis of diatom communities. However, the existing methodology is poorly formalized: standard ecological approaches are not applicable for the pairwise comparison of two samples (from a water body and a corpse), and conclusions often rely on subjective visual assessment. This creates a gap in the objective, statistically sound interpretation of results, limiting the evidentiary value of the examination. OBJECTIVE: to develop a formalized method for the digital dual comparative taxonomic analysis of diatom plankton and its implementation as an accessible web application for forensic medical practice. MATERIAL AND METHODS: The study design involved the development of a comparative taxonomic analysis protocol and its implementation as a web application compatible with Windows, Linux, Android, and iOS operating systems. The protocol includes three blocks of complementary metrics for pairwise comparison: 1) overall similarity (Bray-Curtis and Hellinger distances with a bootstrap test), 2) dominance structure (Jaccard, Sørensen-Dice, and Simpson indices, rank correlations), and 3) stability and indicator value (adapted Dufrêne-Legendre metrics). The application code was written in JavaScript and Python. RESULTS: A formalized method of dual comparative taxonomic analysis was developed, replacing subjective assessment with the calculation of objective metrics, and the free online application "Qualitative Dual Sample Taxa Analyzer" was created. A key element of the application is the bootstrap procedure, which provides statistical testing of the hypothesis about the common origin of samples from a single water body. The combination of metrics allows for a multi-level analysis (integral similarity, core of dominant taxa, contribution of individual species), and the web interface makes the method accessible to experts by automating calculations, standardizing the procedure, and generating a detailed report. CONCLUSIONS: The proposed method of comparative taxonomic analysis and the software tool represent a comprehensive solution for the objective and statistically valid assessment of the similarity of diatom communities. Their implementation in practice can enhance the evidentiary value, reproducibility, and standardization of forensic medical conclusions regarding the determination of the drowning site, which aligns with the general trends of digitalization in expert practice.