Live from the N. Atlantic, Mike Sieracki and Nicole Poulton (Bigelow Laboratory) provide these insights into the phytoplankton community using FlowCAM and flow cytometric analyses.

Diatom images from the FlowCAM imaging-in-flow system.

The community at CTD#1, 3.5m is dominated but Chaetoceros (left). Many healthy looking chains, but some look on their way out with lots of attached cells (maybe choanoflagellates along for the ride?). Some diatom aggregates were seen.

Size histogram of phytoplankton < 20µm.

This size spectra is from the near-surface bottle (3.5m) on our first CTD cast. The data is from our Facscan flow cytometer. The peak to the left is from the prokaryote, Synechococcus,and the one to the right is from small eukaryotes, probably mostly flagellates. The biomass in the sample was dominated by chain diatoms. These are not seen by the Facscan (but, stay tuned for FlowCAM pics and data up to 200µm!). We almost always see a dip in size spectra between prokaryotes and eukaryotes, reflecting their fundamentally different biology. Note this is very preliminary and we will be updating our data with more accurate calibrations (size is from forward light scatter) in the future. And we will convert size and abundances (both axes) to carbon biomass units.