Morphological phytoplankton counts for the SOMLIT-Astan time-series (2007-2017)

The present text file includes morphologic microscopic counts for SOMLIT-Astan station (Western English Channel). Samples (250 mL) of natural seawater intended for the acquisition of microscopic counts were preserved with acid Lugol’s iodine (Sournia, 1978, Guilloux et al. 2013), stored in the dark, and further processed between 15 days and up to 1 year after sampling.

The morphological taxa contingency table was carefully examined to detect inconsistencies (e.g., abrupt changes in cell counts over the time series), and taxa for which identification was uncertain were grouped into broader taxonomic categories. For example, Fragilaria and Brockmaniella or Cylindrotheca closterium and Nitzschia longissima which are difficult to distinguished between each other, were considered in association in the same group of microscopic counts. The final morphological dataset consisted of counts of 146 taxonomical entities (taxa larger than 10µm in size) across 185 dates from 2007 to 2017.

Raw microscopic counts were regularly stored in a local MS-Access database and uploaded in the RESOMAR PELAGOS (http://abims.sb-roscoff.fr/pelagos/) national database.