Vertical and Seasonal Patterns Control Bacterioplankton Communities at Two Horizontally Coherent Coastal Upwelling Sites off Galicia (NW Spain)

Abstract

Analysis of seasonal patterns of marine bacterial community structure along horizontal and vertical spatial scales can help to predict long-term responses to climate change. Several recent studies have shown predictable seasonal reoccurrence of bacterial assemblages. However, only a few have assessed temporal variability over both horizontal and vertical spatial scales. Here, we simultaneously studied the bacterial community structure at two different locations and depths in shelf waters of a coastal upwelling system during an annual cycle. The most noticeable biogeographic patterns observed were seasonality, horizontal homogeneity, and spatial synchrony in bacterial diversity and community structure related with regional upwelling-downwelling dynamics. Water column mixing eventually disrupted bacterial community structure vertical heterogeneity. Our results are consistent with previous temporal studies of marine bacterioplankton in other temperate regions and also suggest a marked influence of regional factors on the bacterial communities inhabiting this coastal upwelling system. Bacterial-mediated carbon fluxes in this productive region appear to be mainly controlled by community structure dynamics in surface waters, and local environmental factors at the base of the euphotic zone.

The Polar Night Shift: Annual Dynamics and Drivers of Microbial Community Structure in the Arctic Ocean

“…2, 5, Extended Data Fig. 6) followed the breakdown of summer stratification 74,75 , with highest mixing of the water column in January (Fig. 5a).…”

Depth-Differentiation and Seasonality of Planktonic Microbial Assemblages in the Monterey Bay Upwelling System

“…The lownutrient conditions likely favor oligotrophic groups such as SAR11 and picocyanobacteria, which appear to dominate shallow waters during the oceanic season (Figure 3 and Supplementary Figures S6, S7). Studies in other marine systems have also reported peaks in diversity during the winter season, usually attributed to increased water column mixing (e.g., Gilbert et al, 2009;Chow et al, 2013;Garcia et al, 2015;Hernando-Morales et al, 2018). In Monterey Bay, this pattern may result from the transport of offshore taxa under post-upwelling conditions.…”

“…Seasonality in microbial community structure has been examined in several marine environments, including in upwelling-influenced coastal systems (e.g., Fuhrman et al, 2006;Giovannoni and Vergin, 2012;Chow et al, 2013;Lindh et al, 2014;Alonso-Saez et al, 2015;Cram et al, 2015;Hernando-Morales et al, 2018;Lambert et al, 2019). Long term time-series sampling of microbial communities in several ocean regions have revealed recurring patterns in community composition, often with substantial depth-based variations in the temporal dynamics (e.g., Steele et al, 2011;Chow et al, 2013;Cram et al, 2015;Hernando-Morales et al, 2018). In dynamic coastal regions, such periodic and deterministic changes in community structure has been linked to seasonal phytoplankton blooms (e.g., Needham and Fuhrman, 2016;Teeling et al, 2016;Camarena-Gómez et al, 2018; also reviewed in Bunse and Pinhassi, 2017).…”

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

“…Few studies have focused on the microbial composition of plankton communities of the world's upwelling regions. 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).…”