“…These total abundance values of viruses enumerated in groundwater were similar to results obtained from other groundwater sites (Kyle et al, 2008; Roudnew et al, 2012). Virus abundance in this shallow aquifer was strongly correlated to cell abundance (ρ = 0.73, p < 0.001) (Figure 2C) and is consistent with prior studies comparing virus and cell abundance in aquatic and sedimentary environments including lakes (Maranger and Bird, 1995; Bettarel et al, 2006; de Araújo and Godinho, 2009; Barros et al, 2010), marine waters (Alonso et al, 2001; Pereira et al, 2009), marine surface sediments (Danovaro and Serresi, 2000), marine subsurface sediment (Bird et al, 2001; Engelhardt et al, 2014), and deep granitic groundwater (Kyle et al, 2008). The virus-to-microbial cell ratio (VMR) in this shallow aquifer ranged from 1.1 to 8.1 and averaged 3.0 ± 1.6 (mean ± S.D., n = 20; Figures 1C,F).…”