Name: David Keller

Email: dkeller@hpl.umces.edu

Author: David P. Keller* and Raleigh R. Hood

Author affiliation: University of Maryland Center for Environmental Science, Horn Point Laboratory, Cambridge, MD 21613

Abstract title: The Role of Viruses in a Model of Seasonal Dissolved Organic Matter Cycling at Station CB3.3C in the Chesapeake Bay, USA

Absstract:

The enormous size and reactivity of the pool of dissolved organic matter (DOM) in marine waters makes it a critical but poorly understood component of global biogeochemical cycling. Understanding the sources, sinks, and mechanisms that drive DOM cycling is important because small changes in marine DOM can potentially effect a large change in other pools (such as atmospheric CO2). In order to better understand DOM cycling in an area where both allochthonous and autochthonous sources of DOM are important we constructed a model to simulate the mean seasonal cycle of DOM in the surface waters of the Chesapeake Bay estuary. Viruses, of both phytoplankton and bacteria, were an important component of the model and played a significant role in seasonal DOM cycling. The results of running the model show that viruses influenced DOM cycling in a number of ways. First, viruses had an influence on the structure of the plankton community by acting as agents of mortality for both phytoplankton and bacteria. Thus, affecting the flow of carbon and nitrogen through the food web and influencing the magnitude of DOM production from processes such as phytoplankton exudation. Second, viral lysis was a major source of DOM, especially dissolved organic nitrogen (DON), in the summer. Finally, the model also indicates that the decay of viruses may be an important source of bioavailable DOM throughout the year.