Zonation of bacterioplankton communities along aging upwelled water in the northern Benguela upwelling

Abstract

Upwelling areas are shaped by enhanced primary production in surface waters, accompanied by a well-investigated planktonic succession. Although bacteria play an important role in biogeochemical cycles of upwelling systems, little is known about bacterial community composition and its development during upwelling events. The aim of this study was to investigate the succession of bacterial assemblages in aging upwelled water of the Benguela upwelling from coastal to offshore sites. Water from the upper mixed layer at 12 stations was sampled along two transects from the origin of the upwelling to a distance of 220 km. 16S rRNA gene amplicon sequencing was then used in a bacterial diversity analysis and major bacterial taxa were quantified by catalyzed reporter deposition-fluorescence in situ hybridization. Additionally, bacterial cell numbers and bacterial production were assessed. Community statistical analysis revealed a reproducible zonation along the two transects, with four clusters of significantly different microbial assemblages. Clustering was mainly driven by phytoplankton composition and abundance. Similar to the temporal succession that occurs during phytoplankton blooms in temperate coastal waters, operational taxonomic units (OTUs) affiliated with Bacteroidetes and Gammaproteobacteria were dominant during algal blooming whereas “Pelagibacterales” were highly abundant in regions with low algal abundance. The most dominant heterotrophic OTU (9% of all reads) was affiliated with “Pelagibacterales” and showed a strong negative correlation with phytoplankton. By contrast, the second most abundant heterotrophic OTU (6% of all reads) was affiliated with the phylum Verrucomicrobia and correlated positively with phytoplankton. Together with the close relation of bacterial production and phytoplankton abundance, our results showed that bacterial community dynamics is strongly driven by the development and composition of the phytoplankton community.

Spatiotemporal Distribution of Key Pelagic Microbes in a Seasonal Oxygen-Deficient Coastal Upwelling System of the Eastern South Pacific Ocean

“…In fact, upwelling favorable winds cumulative intensity denoted an evident interannual upwelling variability during our study timeframe, characterized by a delayed and less intense events triggered during 2005-2006 ( Supplementary Figure 1). The influence of upwelling variability on nonphotosynthetic picoplankton has been reported in other seasonal upwelling ecosystems, such as, northwestern Indian Ocean (Wiebinga et al, 1997) and Benguela (Bergen et al, 2015) and agrees with previous results from the study area (Cuevas et al, 2004;Daneri et al, 2012).…”

Marine Microbial Community Composition During the Upwelling Season in the Southern Benguela

“…Alonso-Gutiérrez et al (2009) revealed seasonal changes in the bacterioplankton community structure in the coastal upwelling region of "Ría de Vigo, " NW Spain, driven by Roseobacter, Bacteroidetes, and SAR86, as in this study. Bergen et al (2015) also revealed high abundances of Bacteroidetes and Gammaproteobacteria in productive upwelled waters in the Northern Benguela, in contrast to an abundance of Pelagibacterales in less productive waters, as also found in this study (i.e., Figures 4, 6).…”

“…These include Painting (1989) who also focused on the Southern Benguela, Kerkhof et al (1999) investigated the North Atlantic just off the New Jersey coast, Suzuki et al (2001) investigated an upwelling region in Monterey Bay in the NE Pacific and Teira et al (2009) studied six key bacterial groups in the Northwest Iberian Peninsula coastal upwelling waters. Only a handful of studies have included next generation sequencing techniques, which are capable of describing community diversity and structure in great detail (e.g., Bergen et al, 2015;Aldunate et al, 2018). These studies revealed a high occurrence of Bacteroidetes, Roseobacter, and SAR86 clade of gammaproteobacteria in upwelling waters.…”

Spatiotemporal dynamics of marine microbial communities following a Phaeocystis bloom: biogeography and co‐occurrence patterns

“…Accumulated evidence indicates that the non‐random distributions of microbial communities might follow a scale‐dependent distance‐decay relationship, and the increased spatial distance can usually limit the dispersal of microbes and contribute to accelerated speciation (Nemergut et al ., 2013; Liang et al ., 2015). Microbial biogeography is driven by ocean currents, water mass or up‐and down‐welling processes to create a distance‐decay pattern (Agogue et al ., 2011; Wilkins et al ., 2013; Bergen et al ., 2015); however, such a dispersal process was strongly context dependent and affected by depth, geographical range and perhaps season (Milici et al ., 2016).…”