The importance and distinctiveness of small-sized phytoplankton in the Magellan Straits

Type Article
Date 2011
Language English
Author(s) Zingone Adriana1, Sarno Diana2, Siano Raffaele2, Marino Donato1
Affiliation(s) 1 : Ecology and Evolution of Plankton, LEEP, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Naples, Italy
2 : Taxonomy and IdentiWcation of Marine Phytoplankton, TIMP, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Naples, Italy
Source Polar Biology (0722-4060) (Springer), 2011 , Vol. 34 , N. 9 , P. 1269-1284
DOI 10.1007/s00300-010-0937-2
WOS© Times Cited 13
Keyword(s) Lennoxia faveolata, Periantarctic areas, Picoeukaryotes, Pycnococcus provasolii, Size structure
Abstract The distribution of summer phytoplankton across the Straits of Magellan (SOM) was studied with the aims of tracing differences among the distinct subregions of the area and contributing to the knowledge of its biodiversity. Samples collected at 25 stations were observed and counted in light microscopy. Selected samples were observed with transmission electron microscopy. The main unifying feature of the phytoplankton in the SOM was the high abundance and numerical dominance of small-sized (<10 μm) eukaryotic species, among which coccoid cells of <3 μm size were predominant (56.2 ± 30.6 of the total phytoplankton abundance). They mostly belonged to the prasinophyte Pycnococcus provasolii, which was abundant (0.8–6,834 cells × 103 ml−1) at all stations with the exception of those in proximity to the Atlantic entrances, where it was not recorded. Small-sized (<3 and 3–5 μm) diatoms (Minidiscus trioculatus, Lennoxia faveolata and other undetermined centric species) attained high densities (<3,757 cells 103 ml−1) especially at stations of the Patagonian sectors, whereas microplanktonic diatoms were only found at the two entrances of the Straits. Dinoflagellates were constituted mainly by >10 μm forms in the Andean subregion and <10 μm naked species in the Patagonian subregion, contributing up to 75.9 and 41.8% of the total carbon in these two areas, respectively. In the Patagonian subregion, flagellates mainly constituted by <5 μm forms and by cryptomonads <10 μm comprised up to 53.9% of the total biomass. Several species identified in this study have never been reported in other investigations in the SOM, while others, including Pycnococcus provasolii and Lennoxia faveolata, have rarely been recorded elsewhere. Overall, the summer phytoplankton of the Straits does not resemble that of any other region of the world’s seas. Although some of the predominant species might have been overlooked elsewhere, their abundance and relative importance apparently constitute a distinctive feature of the SOM.
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