Sampling was performed at the SOMLIT-Astan long-term observatory site (48° 46' 40 N, 3° 56' 15 W) at 10:30 local time during the 2012 summer solstice. Water was collected from a depth of 1 meter using a Niskin bottle. Water samples were transported to the lab in an acid cleaned plastic bottle within 15 minutes and filtered. Within 30 minutes, 4 replicates of 1 liter were filtered for metagenomic analyses using the Sterivex 0.22µm filters. Filters were sealed and immediately frozen at ‐80 °C in individual zip‐lock bags.
Pictures were taken by Service Mer-Station Biologique de Roscoff