Constraints on viral production in the Sargasso Sea and North Atlantic

During the spring of 2005, the production rate of virus-like particles as well as microbial and biogeochemical parameters in the Sargasso Sea and North Atlantic Ocean were investigated as part of a multifaceted North Atlantic Spring Bloom (NASB2005) survey. Here we present data on the spatial variations in viral production rate, abundance, and infection of microbial host populations, in an attempt to understand the constraint(s) on the rates of viral production and abundance. As expected, virus-like particle densities increased from the oligotrophic waters of the Sargasso Sea to the more productive northern Atlantic waters. Additionally, viral production rates increased across the Sargasso Sea transect and correlated with trophic status (chl a concentrations) and secondary (bacterial) productivity in this region. However, no clear pattern of viral production rates could be discerned in waters hosting the NASB. Results of both parametric and non-parametric analyses demonstrate that viral production rates and abundances only correlate well for our observations within the constant 'stability' of the Sargasso Sea, but suggest that more complex relationships including a threshold effect, may guide viral parameters in the North Atlantic. Overall, this study highlights the spatial and potentially temporal complexity of constraints on viral production and ultimately on viral function in surface marine waters.