Field observations on rare or overlooked dinoflagellates from the Argentine Sea

FABRO, E.; ALMANDOZ, G. O.

boletín de la Sociedad Argentina de Botánica

sociedad argentina de botánica

Año: 2021

0373-580X

Background and aims: Planktonic dinoflagellates have a great ecological significancein marine environments. While some dinoflagellate species commonly reach bloomconcentrations and are thus conspicuous components of marine phytoplankton, othersoccur in very low abundances which make them difficult to detect in field studies.Here we analyzed dinoflagellate composition and abundance in five oceanographicexpeditions carried out in continental shelf and slope waters of the Argentine Sea.M&M: Plankton abundance was estimated by the Utermöhl method, using invertedmicroscopy, whereas further optical and scanning electron microscopy was applied forthe identification of dinoflagellate species.Results: We focused on the occurrence of seven dinoflagellates that have beenpreviously poorly documented or overlooked in marine environments worldwide:Dinophysis microstrigiliformis; Gyrodinium sp.; Karlodinium elegans; Oxytoxumlaticeps; Peridiniella danica; Peridiniella globosa and Prorocentrum nux. The latestand K. elegans are observed for the first time in field conditions after their originaldescriptions based on cell cultures. While most species were detected in low ormoderate abundances, P. nux, which is the smallest Prorocentrum species, reached82,000 cells L-1 in slope waters. Very small Gyrodinium cells (11.5 μm long; 8.7 μmwide) with a distribution restricted to slope waters during spring, were not possible tobe accurately assigned to a species.Conclusions: This study contributes to the understanding of dinoflagellate diversity inthe Argentine Sea and the worldwide distribution of little known species.