The energy–diversity relationship of complex bacterial communities in Arctic deep-sea sediments

Abstract

The availability of nutrients and energy is a main driver of biodiversity for plant and animal communities in terrestrial and marine ecosystems, but we are only beginning to understand whether and how energy–diversity relationships may be extended to complex natural bacterial communities. Here, we analyzed the link between phytodetritus input, diversity and activity of bacterial communities of the Siberian continental margin (37–3427 m water depth). Community structure and functions, such as enzymatic activity, oxygen consumption and carbon remineralization rates, were highly related to each other, and with energy availability. Bacterial richness substantially increased with increasing sediment pigment content, suggesting a positive energy–diversity relationship in oligotrophic regions. Richness leveled off, forming a plateau, when mesotrophic sites were included, suggesting that bacterial communities and other benthic fauna may be structured by similar mechanisms. Dominant bacterial taxa showed strong positive or negative relationships with phytodetritus input and allowed us to identify candidate bioindicator taxa. Contrasting responses of individual taxa to changes in phytodetritus input also suggest varying ecological strategies among bacterial groups along the energy gradient. Our results imply that environmental changes affecting primary productivity and particle export from the surface ocean will not only affect bacterial community structure but also bacterial functions in Arctic deep-sea sediment, and that sediment bacterial communities can record shifts in the whole ocean ecosystem functioning.

Geo-Chip analysis reveals reduced functional diversity of the bacterial community at a dumping site for dredged Elbe sediment

“…At present, little is known about the relationship between the functional diversity of bacterial communities and the bioavailability of nutrients or contaminants. Recently, Bienhold et al (2012) reported a close relationship between energy availability and the functional diversity of sediment bacterial communities, which supports our hypothesis. The bioavailability of sediments is determined through several physicochemical factors, such as temperature, salinity, pH or redox potential (Forstner, 1989;Langston and Pope, 1995).…”

Trade-offs between microbiome diversity and productivity in a stratified microbial mat

“…However, the species-energy theory has largely been examined from an macroecological framework and remains nascent within microbial ecology as a discipline; but see discussions by Prosser et al, 2007. An exception to this has been presented in a study focused on the energy-diversity relationships in arctic seafloor microbial ecosystems (Bienhold et al, 2012). This study reported overall positive relationships between species richness and energy availability provided in the form of photosynthetically derived detritus.…”

“…Although the relationship between community productivity and species diversity has been frequently investigated, a unifying consensus on the shape of the relationship is lacking (Rajaniemi, 2003;Bienhold et al, 2012). Similar ecosystems show different productivity-diversity relationships depending on the spatial scale of observation (Chase and Leibold, 2002;Grace et al, 2016).…”

River organic matter shapes microbial communities in the sediment of the Rhône prodelta

“…The structure or function of sediment microbial communities has been linked with pigment concentrations, used as indicators of OM freshness (Polymenakou et al, 2005;Franco et al, 2007;Bienhold et al, 2012), but other classes of compounds, which might give relevant insight both into the lability and origin of the organic component, are often not considered. For instance, the state of degradation of the OM can be estimated from its amino acid composition using the degradation index) (Dauwe and Middelburg, 1998), whereas the carbon isotopic signature (d 13 C) can be used to assess OM origin (Hedges et al, 1997).…”