Data from: Everything is not everywhere: marine compartments shape phytoplankton assemblages
Spatharis, Sofie et al. (2019), Data from: Everything is not everywhere: marine compartments shape phytoplankton assemblages, Dryad, Dataset, https://doi.org/10.5061/dryad.qfttdz0c8
Morphological species identification
Seawater of 1 liter was immediately preserved with a mixture of neutralized formaldehyde and acidic Lugol’s iodine solution at a ratio of 6:1. Two methods were applied for the quantitative analysis of phytoplankton communities, (a) the standard method of cell counting under a Zeiss AxioVert 100 inverted microscope , preceded by serial sedimentations and final concentration of individuals into settling chambers of 25 ml, and (b) sample filtration (300 ml, 2 replicates) through nitrate cellulose membranes of 0.45 μm mesh  followed by transillumination of the filter with immersion oil and observation under a Zeiss Axiolab upright microscope. This approach was adopted due to the observed underestimation of the smaller fraction of phytoplankton (<10 μm) by the Utermöhl method. A graph of the cumulative number of species (y axis) over new fields of vision (x axis) was plotted for 30 random samples to estimate the optimal sample surveying effort. The levelling off of this accumulation curve indicated the minimum number of fields to be counted in the specific magnification to provide a good sample representation. The results for both methods were expressed as number of cells per liter and combined in a single dataset.
Action ARISTEIA II of the Operational Program 'Education and Lifelong Learning' (Action’s Beneficiary: General Secretariat for Research and Technology), and co-financed by the European Social Fund (ESF) and the Greek State., Award: project ECOGENE (Code Number 4691)