Complex analysis of marine particles of various nature using a submersible digital holographic camera at a drifting arctic station.

The paper presents the results of a complex analysis of marine particles collected during the SP-42 drifting expedition (October 2024 - March 2025) aboard the ice-resistant platform "SEVERNY POLIUS" (IRP). Data were acquired using the DHC-FOCL probe, which includes a digital holographic camera. The study aims to obtain in situ time series of mesozooplankton concentration, investigate its diurnal rhythm under polar night conditions, quantify the anthropogenic trace of the IRP, and generate a high-quality dataset of Arctic Ocean marine particles for further neural network training. This made it possible to obtain data on the background concentrations of zooplankton (8,000 pcs/m3) and demonstrate the preservation of circadian rhythms (24 hours) in the absence of solar insolation. Furthermore, it was possible to quantify the organic suspension plume from platform discharges (background exceeded 3-8 times within 3-5 days). A validated dataset comprising 2,769 holographic images of plankton particles from dominant Arctic taxa was compiled. The work highlights the potential of digital holography as a foundation for robust bioindication systems in polar regions.