Speaker
Description
The marine microbiome modulates oceanic biogeochemical cycles and is strongly influenced by microbe-to-microbe interactions, including interactions between phytoplankton (the base of the food web) and heterotrophic bacteria. These interactions range along a continuum of positive to negative impacts on the phytoplankton, affecting ecosystem function, and are difficult to discern in the complex natural environment. Controlled lab experiments offer the ability to advance understanding of the specificity, stability, and dynamics of microbe-to-microbe interactions, but are often limited in the scope and range of conditions tested. To address this, we are developing and streamlining a high-throughput 96-well microcosm approach that facilitates varying numerous important ecologically relevant factors in a single experiment. Here, we apply this approach to explore how phytoplankton bloom species, scale, and stage impact bacterioplankton response by observing wild bacterial community response to different doses and forms – as growing cells, necromass, and DOM – produced from three species of phytoplankton, Chaetoceros calcitrans, Prorocentrum minimum, Rhodomonas salina. Daily samples were taken from microcosms over 12 days for biomass and microbial community composition. We observed distinct bacterial communities in response to different treatments, for example predominance of Vibrionaceae with phytoplankton necromass, Marinomonadaceae with dilute live phytoplankton, Pseudoalteromonas with higher concentration of live phytoplankton and DOM, and Rhodobacteraceae with DOM. These results suggest different conditions select for different bacterial communities that inform the function of marine microbiomes at micro and macro scales.
