Phytoplankton and protozooplankton on the southern Patagonian shelf (Argentina, 47°-55°S) in late summer: potentially toxic species and community assemblage structure linked to environmental features

ANTACLI J.C.; SILVA, R.I.; JAUREGUIZAR A.J.; HERNÁNDEZ, D.R.; MENDIOLAR M.; SABATINI M.E.; AKSELMAN, R.

JOURNAL OF SEA RESEARCH

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2018 vol. 140 p. 63 - 80

1385-1101

On the southern Patagonian shelf (Argentina, 47°-55°S) phyto- and protozooplankton are key structural and functionalcomponents of a complex trophic web that sustains commercially important species. During late summer 2004, spatialstructure, assemblage species and their association with environmental characteristics of water masses were studiedfor the 2-200 μm phyto- and protozooplankton communities. Ultraplankton 2-5 μm was the most abundant size-fraction(90%), followed by the lower nanoplankton 5-10 μm (7.5%), the larger nanoplankton 10-20 μm (1.5%), andmicroplankton 20-200 μm (1%). Several of the 319 morpho-species found are potentially toxic taxa (the dinoflagellatesAlexandrium tamarense, Protoceratium reticulatum, Dinophysis acuminata, Prorocentrum cordatum, Karenia andamphidomataceans and the diatom genus Pseudo-nitzschia), and this is important since the area sustains significantfisheries. A ultraphytoeukaryotic coccal cell (probably chlorophyte/prasinophyte) (3 μm), P. cordatum, and amicroplankton naked ciliate were the morpho-species with the highest abundance and occurrence. Abundance andbiodiversity patterns indicated that the plankton community structure was heterogeneous vertically, cross-shelf, andalong-shelf, suggesting shifts in community structure over the region. Five areas with dissimilar plankton assemblageswere defined, each corresponding to different environments. Depth, bathymetry, latitude and temperature were themost explanatory variables for the assemblage distribution patterns observed. This south Patagonian regionpossesses important fisheries and, considering expected environmental changes, our results help to understand thespatial structure of plankton communities over a broad size spectrum.