Nutrient enrichment induces dormancy and decreases diversity of active bacteria in salt marsh sediments

Abstract

Microorganisms control key biogeochemical pathways, thus changes in microbial diversity, community structure and activity can affect ecosystem response to environmental drivers. Understanding factors that control the proportion of active microbes in the environment and how they vary when perturbed is critical to anticipating ecosystem response to global change. Increasing supplies of anthropogenic nitrogen to ecosystems globally makes it imperative that we understand how nutrient supply alters active microbial communities. Here we show that nitrogen additions to salt marshes cause a shift in the active microbial community despite no change in the total community. The active community shift causes the proportion of dormant microbial taxa to double, from 45 to 90%, and induces diversity loss in the active portion of the community. Our results suggest that perturbations to salt marshes can drastically alter active microbial communities, however these communities may remain resilient by protecting total diversity through increased dormancy.

Resistant ammonia‐oxidizing archaea endure, but adapting ammonia‐oxidizing bacteria thrive in boreal lake sediments receiving nutrient‐rich effluents

“…This was especially pronounced in the three most wastewater‐influenced lakes, Petäjävesi, Saarijärvi and Lievestuore. Similar to general nitrogen additions (e.g., Kearns et al ., ), wastewater favoured the abundance of only certain specialized taxa, for example, Bacteroidetes , Firmicutes , Beta ‐, Epsilon ‐ and/or Gammaproteobacteria . These groups are known to migrate from WWTPs to lake sediments (Saarenheimo et al ., ).…”

Effects of organic matter and low oxygen on the mycobenthos in a coastal lagoon

“…However, activation of dormant fungal cells by the added organic matter could also explain the rapid changes in the mycobenthos community structure observed in our experiment. Similarly, bacterial communities in coastal sediments contain large numbers of dormant cells, whose activity fluctuates on hour timescales in response to rapid changes in O 2 consumption due to increased nutrient additions (Kearns et al ., ). Our finding that the number of mycobenthos taxa decreases under nutrient addition (Fig.…”

“…Our finding that the number of mycobenthos taxa decreases under nutrient addition (Fig. B) is also similar to the effects of nutrient addition on Bacteria in salt marsh sediments, where increased nutrients causes a loss of diversity in the active fraction of the bacterial community (Kearns et al ., ).…”

Predator trait evolution alters prey community composition

“…Our structural equation models suggest that the historical nutrient treatment decreased bacterial species richness directly, which may have occurred through ecological changes in species composition or evolutionary changes within the species comprising the bacterial community (Kearns et al. ). However, the historical environment also affected the bacterial community indirectly, via evolutionary changes in Colpidium traits (Fig.…”