One of several ways in which climate change will affect aquatic ecosystems is by increasing maximum, minimum, and mean annual temperatures. Increasing temperatures will likely alter microbial processes. However, the microbiomes of running (lotic) and still (lentic) aquatic ecosystems are likely to be affected by increasing temperatures through different mechanisms because of the difference in lifestyle between the dominant microbiome in each ecosystem. In lentic ecosystems, free-living pelagic microbes dominate the ecosystem’s metabolism. In lotic ecosystems, interstitial biofilms dominate the ecosystem’s metabolism. Pelagic and biofilm forming microbes represent two distinct microbial lifestyles that have overlapping but not redundant membership. I use a combination of observational and experimental approaches to illustrate similarities and differences in the mechanisms that underlie how increasing global temperatures are likely to affect aquatic microbiomes in lentic and lotic ecosystems.
Results/Conclusions
In both lentic and lotic ecosystems resource limitation leads to a more pronounced response to warmer temperatures. Initially warmer temperatures lead to respiration increasing more rapidly than production, resulting in a decreased carbon use efficiency. Sustained warming can alter competitive ability and lead to shifts in microbiome membership. In pelagic ecosystems this often means cell death or competitive exclusion. However in interstitial biofilms microbes may also leave as living propugules and re-establish biofilms downstream in more favorable habitats. The interaction in differences in resource availability, microbial lifestyle, and physiological response to warming are likely to affect lentic and lotic ecosystems differently. In this talk I discuss how the similarities and differences in microbial mechanisms are likely to affect how each aquatic ecosystem responds to warming habitats.