Variability of the microbial community in the western Antarctic Peninsula from late fall to spring during a low ice cover year

• Published in: Polar Biology
• Main Authors: Moreau, S, Ferreyra, A, Mercier, B, Lemarchand, K, Lionard, M, Roy, S, Mostajir, B, van Hardenberg, B, Demers, S
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer-Verlag 2010
• Subjects: Earth Sciences; Oceanography; Biological Oceanography; Antarctic; Antarctic Peninsula; Melchior; Antarc*; Polar Biology; Sea ice
• Online Access: https://doi.org/10.1007/s00300-010-0806-z; http://ecite.utas.edu.au/109556

Although winter conditions play a major role in determining the productivity of the western Antarctic Peninsula (WAP) waters for the following spring and summer, a few studies have dealt with the seasonal variability of microorganisms in the WAP in winter. Moreover, because of regional warming, sea-ice retreat is happening earlier in spring, at the onset of the production season. In this context, this study describes the dynamics of the marine microbial community in the Melchior Archipelago (WAP) from fall to spring 2006. Samples were collected monthly to biweekly at four depths from the surface to the aphotic layer. The abundance and carbon content of bacteria, phytoplankton and microzooplankton were analyzed using flow cytometry and inverted microscopy, and bacterial richness was examined by PCRDGGE. As expected, due to the extreme environmental conditions, the microbial community abundance and biomass were low in fall and winter. Bacterial abundance ranged from 1.2 to 2.810 5 cellsml −1 showing a slight increase in spring. Phytoplankton biomass was low and dominated by small cells (<2μm) in fall and winter (average chlorophyll a concentration, Chl- a , of, respectively, 0.3 and 0.13μgl −1 ). Phytoplankton biomass increased in spring (Chl- a up to 1.13μgl −1 ), and, despite potentially adequate growth conditions, this rise was small and phytoplankton was still dominated by small cells (220μm). In addition, the early disappearing of sea-ice in spring 2006 let the surface water exposed to ultraviolet B radiations (UVBR, 280320nm), which seemed to have a negative impact on the microbial community in surface waters.