Dataset: Phytoplankton - Diazotroph Station Counts

Sampling was done with a CTD Rosette with 10 L bottles. After collecting seawater at selected depths, a Swinex filter capsule was attached with tubing to the drain spigot of the water bottle and the entire contents of the bottle was filtered through a 47 mm diameter filter with 10 micrometer pore size. The filter was then placed on an oversize microscope slide and a drop of nonfluorescing immersion oil was placed on the filter which was then covered with a #1 oversize coverslip.

Counts were done using epifluorescence microscopy on ship using a Zeiss Axioskop microscope at 200X with green excitation. Transects were made on the slide, or if the cyanobacteria were very dense, counts were done on fields of view. Counts were made of Trichodesmium trichomes (filaments) in colonies and as free trichomes. Counts of the endosymbiont Richelia intracellularis were noted as heterocysts within several diatom species. Also noted was the filamentous species Katagynemene.