Dataset: Phytoplankton - Synechococcus Station Counts
Deployment: AT21-04

A CTD Rosette with 10L bottles was deployed on station. Water samples were collected at 2, 10, 30, 40, 60, 80 and 100m. Depths of sampling sometimes varied because of the presence of a chlorophyll maximum or other environmental features. 50 ml of seawater from each depth was filtered onto a 0.6 micrometer 25 mm diameter polycarbonate filter and as the last ml remained one ml of a 4% paraformaldehyde solution (made up in 0.2 ml filtered seawater) was added to the filter funnel for 5 minutes. The remaining liquid was then filtered through the filter and the filter was placed on a standard microscope slide. A drop of non-fluorescing immersion oil was placed on the filter, and then it was covered with a #1 cover slip. The slide was labeled and placed in a slide box in a minus 5 degrees freezer for storage. In the shore lab a drop of immersion oil was placed on the coverslip and Synechococcus cells were counted in random fields using a Zeiss Axioskop microscope at 1000X using epiflourercence microscopy and blue excitation. Enough fields were counted to count at least 500 cells. If cells were large and fluoresced  very brightly, it was noted.