Phosphorus resource heterogeneity in microbial food webs

Abstract

Food webs are often regulated by the bottom-up effects of resource supply rate. However, heterogeneity within a resource pool may also affect the structure and function of communities. To test this hypothesis, we measured the responses of aquatic microbial food webs in experimental mesocosms to the addition of 4 different phosphorus (P) sources: orthophosphate (PO 4 3− ), 2-aminoethylphosphonate (AEP), adenosine triphosphate (ATP), and phytic acid (PA). Based on 16S rRNA gene sequencing, we found that P resource heterogeneity altered community assembly for bacteria and eukaryotic algae, suggesting that these microbial functional groups may be comprised of P-specialists. In contrast, cyanobacteria were relatively unaffected by our treatments, suggesting that these microorganisms may adopt a more generalist strategy for Pacquisition. Furthermore, our results revealed that P resource heterogeneity affected food web and ecosystem attributes such as nutrient concentrations, bacterial productivity, algal biomass, and ecosystem respiration. Lastly, we found no evidence for non-additive effects of resource heterogeneity based on a treatment where a set of mesocosms received all 4 sources of P. Instead, our results support the view that there may be non-substitutable classes of P in aquatic ecosystems. Specifically, microbial food webs were more sensitive to P-containing biomolecules (PO 4 3− and ATP) than P-containing structural or storage molecules (AEP and PA). Our results demonstrate that not all P resources are the same; although historically overlooked, P resource heterogeneity may have important implications for understanding and predicting the structure and function of aquatic communities.

Spatiotemporal dynamics and determinants of planktonic bacterial and microeukaryotic communities in a Chinese subtropical river

“…Further, our findings are consistent with reports of microbial communities' responses to nutrient concentrations (Newton and McMahon 2011;Muscarella et al 2014). Nutrient availability plays a critical role in driving the activities and large-scale distributions of freshwater bacteria and phytoplankton communities (Yang et al 2012;Liu et al 2014).…”

Crop rotational diversity increases disease suppressive capacity of soil microbiomes

“…For each sample, PCR product combined from three 50‐μL reactions, concentration quantified, and PCR product from each soil sample was combined in equimolar concentrations for paired‐end 250 × 250 sequencing using the Illumina MiSeq platform according to details in Muscarella et al. (). Briefly, we assembled the paired‐end 16S rRNA sequence reads using the Needleman algorithm (Needleman and Wunsch ).…”

New insights on resource stoichiometry: assessing availability of carbon, nitrogen, and phosphorus to bacterioplankton

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