Pulse Amplitude Modulated (PAM) chlorophyll fluorescence images of Western Channel Observatory (WCO) surface phytoplankton samples collected from the L4 station in August 2024 and May/June 2025

This dataset contains pulse amplitude modulated (PAM) chlorophyll fluorescence images of phytoplankton samples obtained at discrete depths from station L4 of the Western Channel Observatory (50.25N, 04.22W) in August 2024 and May/June 2025. Phytoplankton samples were taken from Niskin bottles deployed from the RV MBA Sepia during routine oceanographic surveys of the station and were photographed approximately 2 hours after collection. Images were acquired with a customised wide-field, high-resolution Mesolens microscope and comprise dark adapted (F0) and light-saturated fluorescence (Fm) conditions, along with corresponding brightfield images to allow identification of single cells. The aim of the project was focused around developing a new method of single cell PAM imaging to provide unprecedented species- or group- specific information on phytoplankton photosynthetic performance. The data were collected as part of the NERC Discovery Science project 'New approaches for understanding group-specific phytoplankton photosynthesis in mixed populations' (grant ref NE/X009742/1), awarded to principal investigator Colin Brownlee at the Marine Biological Association, UK.