Changes in community assemblages during the development of a thin layer of phytoplankton (TLP)

ASLO 2021 Aquatic Sciences Meeting, 22–27 June, Virtual

High resolution measurements of phytoplankton (from pico- to mesoplankton) and physicochemical parameters were made from 2 to 14 July, 2018 in a coastal embayment (Ría de Pontevedra, NW Spain). The main objective of this work was to study changes in phytoplankton community structure during the development of a phytoplankton thin layer. The observational approach highlighted the role of short term changes of abiotic and biotic habitat conditions in the dynamics of phytoplankton assemblages. During relaxation conditions in the beginning of the cruise, small rounded dinoWagellates Alexandrium minutum (PSP toxins) and Scrippsiella cf. dominated. Then, during the transition from downwelling to upwelling conditions, a thin layer was formed, composed of Pseudo-Nitzschia spp (ASP toxins) and Leptocylindrus danicus. Fine spatial (cm-m) and temporal (hours-days) scale measurements were carried out. A combination of traditional microscopy analysis (279 samples analyzed at species level when possible) and imaging-in-Wow technique for morphometric characterization (280 samples generating about 480000 raw images, containing plankton, detritus and mineral particles) allowed us to assess the effect of the environmental =ltering on phytoplankton morphological and functional traits. The dynamics of co-occurring populations of Pseudo-nitzschia spp and Alexandrium minutum was considered in the frame of changing habitat conditions

This study was funded by project REMEDIOS (CTM2016-75451-C2-2-R).

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