Microbial activity during a coastal phytoplankton bloom on the Western Antarctic Peninsula in late summer. Issue 10 (4th April 2018)

• Record Type: Journal Article
• Authors: Alcamán-Arias, María E; Farías, Laura; Verdugo, Josefa; Alarcón-Schumacher, Tomás; Díez, Beatriz
• Is Part Of: FEMS microbiology letters. Volume 365:Issue 10(2018:May)
• Publication Date: 2018-04-04
• Subjects: Antarctic microbial communities -- phytoplankton bloom -- bacterioplankton -- C and N assimilation pathways -- metatranscriptomics; Microbiology -- Periodicals; 579
• DOI: 10.1093/femsle/fny090
• Languages: English
• ISSNs: 0378-1097

Abstract

Abstract: Phytoplankton biomass during the austral summer is influenced by freezing and melting cycles as well as oceanographic processes that enable nutrient redistribution in the West Antarctic Peninsula (WAP). Microbial functional capabilities, metagenomic and metatranscriptomic activities as well as inorganic 13 C- and 15 N-assimilation rates were studied in the surface waters of Chile Bay during two contrasting summer periods in 2014. Concentrations of Chlorophyll a (Chl a ) varied from 0.3 mg m −3 in February to a maximum of 2.5 mg m −3 in March, together with a decrease in nutrients; however, nutrients were never depleted. The microbial community composition remained similar throughout both sampling periods; however, microbial abundance and activity changed with Chl a levels. An increased biomass of Bacillariophyta, Haptophyceae and Cryptophyceae was observed along with night-grazing activity of Dinophyceae and ciliates (Alveolates). During high Chl a conditions, HCO3 − uptake rates during daytime incubations increased 5-fold (>2516 nmol C L −1 d −1 ), and increased photosynthetic transcript numbers that were mainly associated with cryptophytes; meanwhile night time NO3 − (>706 nmol N L −1 d −1 ) and NH4 + (41.7 nmol N L −1 d −1 ) uptake rates were 2- and 3-fold higher, respectively, due to activity from Alpha-/Gammaproteobacteria and Bacteroidetes (Flavobacteriia). Due to a projected acceleration in climate change in the WAP, this information is valuable for predicting the composition and functional changes in Antarctic microbial communities. Abstract : Microbial activities in the marine Antarctic C and N cycles.