Abstract
Abstract. Heterotrophic marine bacteria utilize organic carbon for growth and biomass synthesis. Thus, their physiological variability is key to the balance between the production and consumption of organic matter and ultimately particle export in the ocean. Here we investigate a potential link between bacterial traits and ecosystem functions in the rapidly warming West Antarctic Peninsula (WAP) region based on a bacteria-oriented ecosystem model. Using a data assimilation scheme, we utilize the observations of bacterial groups with different physiological traits to constrain the group-specific bacterial ecosystem functions in the model. We then examine the association of the modeled bacterial and other key ecosystem functions with eight recurrent modes representative of different bacterial taxonomic traits. Both taxonomic and physiological traits reflect the variability in bacterial carbon demand, net primary production, and particle sinking flux. Numerical experiments under perturbed climate conditions demonstrate a potential shift from low nucleic acid bacteria to high nucleic acid bacteria-dominated communities in the coastal WAP. Our study suggests that bacterial diversity via different taxonomic and physiological traits can guide the modeling of the polar marine ecosystem functions under climate change.
Highlights
Microbes regulate many key ecosystem functions in the marine food web
Kim et al.: Modeling polar marine ecosystem functions (Bowman et al, 2017), in which high nucleic acid (HNA) cells are generally larger in both cell and genome size compared to low nucleic acid (LNA) cells (Bouvier et al, 2007; Calvo-Díaz and Morán, 2006)
We explore a potential link between bacterial traits and ecosystem functions in the warming coastal West Antarctic Peninsula (WAP) using a bacteria-oriented ecosystem model modified from the WAP-1D-VAR v1.0 model (Kim et al, 2021)
Summary
Microbes regulate many key ecosystem functions in the marine food web. Unicellular primary producers fix organic carbon (i.e., an ecosystem function termed primary production), while heterotrophic marine bacteria and archaea (hereafter bacteria) utilize the fixed organic carbon for growth and biomass synthesis (i.e., an ecosystem function termed bacterial production, or BP; Azam et al, 1983). Bacteria cluster into two groups of cells with different nucleic acid content, including high nucleic acid (HNA) and low nucleic acid (LNA) cells (Bouvier et al, 2007; Gasol et al, 1999) These two groups are suggested to represent lineages (Schattenhofer et al, 2011; Vila-Costa et al, 2012) or physiological states. Bowman et al (2017) demonstrated that a combination of taxonomy, physiological structure (i.e., HNA and LNA cells), and abundance of bacterial communities explained up to 73 % of the variance in bulk BP Their findings imply that physiological and taxonomic traits of bacteria may inform a predictive ecosystem model to further explore ecologically important questions including the following: would these bacterial traits reflect other important ecosystem functions such as the net primary production and particle sinking flux? Their findings imply that physiological and taxonomic traits of bacteria may inform a predictive ecosystem model to further explore ecologically important questions including the following: would these bacterial traits reflect other important ecosystem functions such as the net primary production and particle sinking flux? If so, what would be the potential mechanisms and how will the relationship between bacterial traits and ecosystem functions be impacted by climate change?
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