High Prevalence of Gammaproteobacteria in the Sediments of Admiralty Bay and North Bransfield Basin, Northwestern Antarctic Peninsula

Abstract

Microorganisms dominate most Antarctic marine ecosystems, in terms of biomass and taxonomic diversity, and play crucial role in ecosystem functioning due to their high metabolic plasticity. Admiralty Bay is the largest bay on King George Island (South Shetland Islands, Antarctic Peninsula) and a combination of hydro-oceanographic characteristics (bathymetry, sea ice and glacier melting, seasonal entrance of water masses, turbidity, vertical fluxes) create conditions favoring organic carbon deposition on the seafloor and microbial activities. We sampled surface sediments from 15 sites across Admiralty Bay (100–502 m total depth) and the adjacent North Bransfield Basin (693–1147 m), and used the amplicon 454-sequencing of 16S rRNA gene tags to compare the bacterial composition, diversity, and microbial community structure across environmental parameters (sediment grain size, pigments and organic nutrients) between the two areas. Marine sediments had a high abundance of heterotrophic Gammaproteobacteria (92.4% and 83.8% inside and outside the bay, respectively), followed by Alphaproteobacteria (2.5 and 5.5%), Firmicutes (1.5 and 1.6%), Bacteroidetes (1.1 and 1.7%), Deltaproteobacteria (0.8 and 2.5%) and Actinobacteria (0.7 and 1.3%). Differences in alpha-diversity and bacterial community structure were found between the two areas, reflecting the physical and chemical differences in the sediments, and the organic matter input.

A Mosaic of Geothermal and Marine Features Shapes Microbial Community Structure on Deception Island Volcano, Antarctica

“…Higher alpha-diversity was observed for both Bacteria and Archaea in glacier samples when compared to fumarole samples. This may be due to seasonal variations of temperature and nutrients in glaciers, which may select different groups of microorganisms and enhance microbial diversity in cold Antarctic ecosystems ( Hopkins et al, 2006 ; Kirchman et al, 2014 ; Bowman et al, 2017 ; Franco et al, 2017 ). Indeed, we identified phylogenetically and functionally distinct groups in our glacier samples, as psychrophilic ( Flavobacterium , Luteolibacter , Rhodoferax , Polaromonas , and Arthrobacter ), methylotrophic ( Methylotenera ), denitrifying ( Rhodanobacter ), and nitrifying ( Nitrospira , Nitrosovibrio ) Bacteria.…”

First Record of Juncaceicola as Endophytic Fungi Associated with Deschampsia antarctica Desv.

“…The establishment and survival of living organisms are limited by conditions such as low temperature and nutrient availability, strong winds, high sublimation and evaporation, frequent freezing-thawing cycles, low annual precipitation, high solar incidence and ultraviolet radiation, and low water availability [2][3][4][5]. In terms of biomass and taxonomic diversity, microorganisms such as bacteria and fungi comprise the dominant groups of most Antarctic ecosystems, because they respond to these conditions successfully [6].…”

Microbial Communities and Their Predicted Metabolic Functions in Growth Laminae of a Unique Large Conical Mat from Lake Untersee, East Antarctica

“…Besides microbial mats in marine and other tropical ecosystems ( Mobberley et al, 2012 ; Louyakis et al, 2017 ), NextGen sequencing technology has been applied to other ecosystems in Antarctica including lakes, sediments, soils, endoliths, and hypoliths. Examples include: (1) benthic mats from Lake Fryxell using Illumina Miseq platform ( Jungblut et al, 2016 ), (2) water samples from Ace Lake using pyrosequencing ( Lauro et al, 2011 ), (3) water samples from Lake Fryxell and Bonney using pyrosequencing ( Vick-Majors et al, 2014 ), (4) soils, endoliths and hypoliths of Victoria Valley in Eastern Antarctica using pyrosequencing ( Van Goethem et al, 2016 ), (5) surface sediments of King George Island and Bransfield Strait of Northwestern Antarctic Peninsula by pyrosequencing ( Franco et al, 2017 ), (6) sediments of freshwater inland lakes and estuarine environment of Byers Peninsula in Antarctica ( Gugliandolo et al, 2016 ), and (7) ice and freshwater water samples from lakes in Schirmacher Oasis of East Antarctica ( Mojib et al, 2009 ).…”