Shifts in microphytoplankton species and cell size at Admiralty Bay, Antarctica

• Published in: Antarctic Science
• Main Authors: Kienteca Lange, P, Rivera Tenenbaum, D, Maria Tavano, V, al., E
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Cambridge University Press 2019
• Subjects: Admiralty Bay; Antarctic; Antarctic Peninsula; The Antarctic; Antarc*; Antarctica
• Online Access: https://doi.org/10.1017/S0954102014000571; https://ora.ox.ac.uk/objects/uuid:0ef93cdb-b057-4558-bad8-64dbe9f98bd9

: Phytoplankton (> 15 µm) was investigated in three shallow coastal areas at Admiralty Bay (AB) between the summers of 2002–03 and 2008–09. Phytoplankton abundance was low (103 cells l-1) and, over time, the prevailing cell size decreased due to a shift in phytoplankton dominant species from diatoms to dinoflagellates. In situ and remote sensing data showed that oscillations in sea surface temperature, precipitation, ice formation/melting, irradiance (cloud cover) and bottom circulation (indexed by the Antarctic Oscillation Index; AAO) were shown to govern the structure of the phytoplankton. Under negative AAO, diatoms prevailed, with the dominance of large (> 80 µm) benthic diatoms (e.g. Corethron pennatum and Navicula directa) in periods of low production (102 cells l-1 in 2002–03), and medium-sized (31–80 µm) centrics (e.g. Thalassiosira spp. and Stellarima microtrias) when the abundance was higher (104 cells l-1 in 2003–04). Conversely, positive AAO led to the co-dominance of dinoflagellates and planktonic diatoms (e.g. Pseudo-nitzschia spp.) in the summers of 2007–08 and 2008–09. These results suggest that the AAO can be a good predictor of phytoplankton in coastal areas around the western Antarctic Peninsula, and may help our understanding of changes in other trophic levels of the food web.