Microbial communities in the nepheloid layers and hypoxic zones of the Canary Current upwelling system

Abstract

Eastern boundary upwelling systems ( EBUS s) are among the most productive marine environments in the world. The Canary Current upwelling system off the coast of Mauritania and Morocco is the second most productive of the four EBUS , where nutrient‐rich waters fuel perennial phytoplankton blooms, evident by high chlorophyll a concentrations off Cape Blanc, Mauritania. High primary production leads to eutrophic waters in the surface layers, whereas sinking phytoplankton debris and horizontally dispersed particles form nepheloid layers ( NL s) and hypoxic waters at depth. We used Catalyzed Reporter Deposition Fluorescence In Situ Hybridization ( CARD ‐ FISH ) in combination with fatty acid (measured as methyl ester; FAME ) profiles to investigate the bacterial and archaeal community composition along transects from neritic to pelagic waters within the “giant Cape Blanc filament” in two consecutive years (2010 and 2011), and to evaluate the usage of FAME data for microbial community studies. We also report the first fatty acid profile of Pelagibacterales strain HTCC 7211 which was used as a reference profile for the SAR 11 clade. Unexpectedly, the reference profile contained low concentrations of long chain fatty acids 18:1 cis 11, 18:1 cis 11 11methyl, and 19:0 cyclo11–12 fatty acids, the main compounds in other Alphaproteobacteria . Members of the free‐living SAR 11 clade were found at increased relative abundance in the hypoxic waters in both years. In contrast, the depth profiles of Gammaproteobacteria (including Alteromonas and Pseudoalteromonas ), Bacteroidetes , Roseobacter , and Synechococcus showed high abundances of these groups in layers where particle abundance was high, suggesting that particle attachment or association is an important mechanisms of dispersal for these groups. Collectively, our results highlight the influence of NL s, horizontal particle transport, and low oxygen on the structure and dispersal of microbial communities in upwelling systems.

The exploration of dominant spoilage bacteria in blue mussels (Mytilus edulis) stored under different modified atmospheres by MALDI-TOF MS in combination with 16S rRNA sequencing

“…arctica were able to grow out with limited O2 levels at the end of storage. This agreed with previous findings that these bacteria were also present in hypoxic marine waters (reaching depeths 3,300 of m) (Ferchiou et al, 2022;Thiele et al, 2019). aerobic and facultative anaerobic bacteria might adapt a very low O2 (0.1%) and/or elevated CO2 levels (> 20%) by decreasing maximum growth rates (Couvert et al, 2023).…”

Switch of Bacteria Community Under Oxygen Depletion in Sediment of Bohai Sea

“…Therefore, the community composition of bacteria and unique biogeochemical cycling processes in hypoxic area have been extensively studied in recent years (Beman and Carolan, 2013;Li et al, 2014;Fuchsman et al, 2019;Sen et al, 2021). Certain bacteria have been reported to be adapted for low-oxygen environments, such as SAR11 bacteria, NC10 bacteria and Protochlorococcus (Füssel et al, 2012;Padilla et al, 2016), which are related to ocean hypoxia and nitrogen loss and generally distributed in the core hypoxic area with high abundance (Thiele et al, 2019) or intensive activity (Tsementzi et al, 2016). In addition, some investigations have determined the metabolic basis for SAR11 and confirmed their role as a model to study the carbon and nitrogen cycles in the OMZs (Tsementzi et al, 2016;Bertagnolli and Stewart, 2018;Ruiz-Perez et al, 2021).…”

Particulate Organic Carbon Deconstructed: Molecular and Chemical Composition of Particulate Organic Carbon in the Ocean

“…Studies can focus on specific genes or use untargeted omics approaches. Commonly applied phylogenetic markers are the 16S (prokaryotic) and 18S (eukaryotic) rRNA genes, used to examine the phylogenetic composition of POCassociated communities and how they change with depth, environmental conditions, and over time (DeLong et al, 2006;Duret et al, 2019;Thiele et al, 2019;Preston et al, 2020).…”