Disentangling top-down drivers of mortality underlying diel population dynamics of<i>Prochlorococcus</i>in the North Pacific Subtropical Gyre

AbstractPhotosynthesis fuels primary production at the base of marine food webs. Yet, in many surface ocean ecosystems, diel-driven primary production is tightly coupled to daily loss. This tight coupling raises the question: which top-down drivers predominate in maintaining persistently stable picocyanobacterial populations over longer time scales? Motivated by high-frequency surface water measurements taken in the North Pacific Subtropical Gyre (NPSG), we developed multitrophic models to investigate bottom-up and top-down mechanisms underlying the balanced control ofProchlorococcuspopulations. We find that incorporating photosynthetic growth with viral- and predator-induced mortality is sufficient to recapitulate daily oscillations ofProchlorococcusabundances with baseline community abundances. In doing so, we infer that grazers function as the primary top-down factor despite high standing viral particle densities while identifying the potential for light-dependent viral traits and non-canonical loss factors to shape the structure and function of marine microbial communities.

Beckett, S. J., Demory, D., Coenen, A. R., Casey, J. R., Dugenne, M., Follett, C. L., ... Weitz, J. S.

Beckett, Stephen J||Demory, David||Coenen, Ashley R||Casey, John R||Dugenne, Mathilde||Follett, Christopher L||Connell, Paige||Carlson, Michael CG||Hu, Sarah K||Wilson, Samuel T||Muratore, Daniel||Rodriguez-Gonzalez, Rogelio A||Peng, Shengyun||Becker, Kevin W||Mende, Daniel R||Armbrust, E Virginia||Caron, David A||Lindell, Debbie||White, Angelicque E||Ribalet, François||Weitz, Joshua S

Disentangling top-down drivers of mortality underlying diel population dynamics ofProchlorococcusin the North Pacific Subtropical Gyre Institutional Repository Document