Diatoms shape the biogeography of heterotrophic prokaryotes in early spring in the Southern Ocean

Abstract

Summary The interplay among microorganisms profoundly impacts biogeochemical cycles in the ocean. Culture‐based work has illustrated the diversity of diatom–prokaryote interactions, but the question of whether these associations can affect the spatial distribution of microbial communities is open. Here, we investigated the relationship between assemblages of diatoms and of heterotrophic prokaryotes in surface waters of the Indian sector of the Southern Ocean in early spring. The community composition of diatoms and that of total and active prokaryotes were different among the major ocean zones investigated. We found significant relationships between compositional changes of diatoms and of prokaryotes. In contrast, spatial changes in the prokaryotic community composition were not related to geographic distance and to environmental parameters when the effect of diatoms was accounted for. Diatoms explained 30% of the variance in both the total and the active prokaryotic community composition in early spring in the Southern Ocean. Using co‐occurrence analyses, we identified a large number of highly significant correlations between abundant diatom species and prokaryotic taxa. Our results show that key diatom species of the Southern Ocean are each associated with a distinct prokaryotic community, suggesting that diatom assemblages contribute to shaping the habitat type for heterotrophic prokaryotes.

Nitrogen cycling in coastal sediment microbial communities with seasonally variable benthic nutrient fluxes

“…These taxonomic differences likely reflect the higher light attenuation of this shallower site and the constant stream of organic material and nutrient inputs that are delivered to these sediments from the Yarra River (Harris et al 1996). Known drivers of microbial community composition (pH, moisture content, organic carbon and N content, chlorophyll α and NH 4 + -N) (Jorgensen et al 2012, Fortunato et al 2013, Fagervold et al 2014, Probandt et al 2017, Wang et al 2018, Liu et al 2019) varied between these sampling sites, and in conjunction with previous research our study supports the findings that HB and CPPB represent both biogeochemically (Murray & Parslow 1999) and microbial distinct sediment habitats.…”

Seasonal dynamics of prokaryotes and their associations with diatoms in the Southern Ocean as revealed by an autonomous sampler

“…The correlations we obtained between a given diatom species and prokaryotic taxa and vice versa were multiple, suggesting that the majority of these associations reflect non‐specific interactions. On the one hand, phytoplankton was shown to explain changes in heterotrophic prokaryotic communities better than environmental parameters on temporal and spatial scales (Lima‐Mendez et al ., 2015; Needham and Fuhrman, 2016; Liu et al ., 2019). On the other hand, the production of common biologically labile substrates is in part independent of the phytoplankton assemblage and was suggested to explain recurrent patterns in prokaryotic community composition (Teeling et al ., 2016).…”

“…The release of a suite of organic compounds by phytoplankton and their processing by diverse taxa is one of the driving processes (Moran et al ., 2016; Mühlenbruch et al ., 2018). The various interactions between phytoplankton species and microbial taxa could additionally lead to shifts in community composition (Amin et al ., 2012; Lima‐Mendez et al ., 2015; Liu et al ., 2019). Long‐term observations are key to identify these patterns and to detect changes in the functioning of microbial communities due to global environmental change.…”

Bacterioplankton dynamics driven by interannual and spatial variation in diatom and dinoflagellate spring bloom communities in the Baltic Sea

“…This suggests the occurrence of a bacterioplankton succession that responds to the increase of diatom-derived DOM by the increase in the bacterial production rates, but also responds to a niche partitioning of the highly diverse bacterial community that exploits different resources. Other studies have also reported higher bacterial diversity during the spring bloom dominated by diatoms in the Baltic Sea and Southern Ocean (Lindh et al 2015;Liu et al 2019). However, there are also contradictory findings with, for example, lower diversity with an increase in Chl a during a Phaeocystis antarctica bloom (Richert et al 2019) and also lower diversity with an increase in PP (Raes et al 2011).…”