Collaborative Research: Constraining virus loss and carbon and nitrogen flow through virovory in temperate marine ecosystems with isotope tracing and microbial food web models.

About This Grant

A quantitative understanding of the flow of nutrients and energy in marine ecosystems is critical to understanding and predict the availability of the resources that support food webs and the capacity of the ocean to store carbon. Viruses play multiple and dynamic roles in the fate of organic matter and the flow of energy in the ocean. Arguably, the least studied of those roles is the direct transfer of nutrients and energy up the food web through grazing on virus particles — virovory. This study investigates how virovory impacts the cycling of organic matter and its contribution to grazers’ nutrition varies in time and space across distinct microbe groups. The work is timely and complementary to large-scale projects to create a predictive understanding of the ocean’s carbon cycle and transform our understanding of the impacts of viruses in the marine environment beyond their role as parasites. This project engages and trains early career scientists and students as scientific partners, providing professional skills critical for careers inside and outside academia, such as science communication and reporting to various audiences. The project also includes participation in STEM programs for middle and high school students. Virus particles and infections play a role in the biological cycling and sequestration of organic matter by increasing the flow of organic matter to the dissolved phase, fueling the microbial loop—‘viral shunt’ and releasing compounds during host cell lysis that enhance the formation of particle aggregates and the sinking of organic matter through the biological pump—‘viral shuttle.’ Quantifying virus decay and removal is critical to constrain infection dynamics, a first step to quantify the ‘shunt’ and ‘shuttle.’ Virovory is a potentially dominant virus loss process, a source of nutrition to grazers, and a significant food web pathway that redirects nutrients and energy to upper trophic levels. However, the magnitude of each of these virally-mediated processes of regeneration, sequestration, and trophic transfer remains largely unresolved. This research team uses laboratory incubations of natural marine microbial communities collected on different seasons from oligotrophic and eutrophic environments with isotope-labeled viral particles and mathematical ecosystem models to test the following hypotheses: H1. Virovory is a natural sink of marine viruses that rivals all other viral losses combined. H2. Nutrient transfer from large enveloped dsDNA eukaryotic viruses is higher than from smaller virus particles. H3. Virovory contributes more nutrition for heterotrophic protists in permanently or seasonally oligotrophic waters than in eutrophic marine ecosystems. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.