Lysogens and free viruses in fresh, brackish, and marine waters: a Bayesian analysis |
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| Authors: | Samuel Choi Ivan Jeliazkov & Sunny C Jiang |
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| Institution: | Environmental Health, Science and Policy, University of California, Irvine, CA, USA;;Department of Economics, University of California, Irvine, CA, USA;and;Civil and Environmental Engineering, University of California, Irvine, CA, USA |
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| Abstract: | A yearlong study was conducted to determine factors that affect the abundance and distribution of lysogens and free viruses at fresh-, brackish-, and saltwater stations in Newport Bay, CA. The viral and bacterial abundance were highest in the freshwater (average 1.1 × 108 and 1.1 × 107 mL?1, respectively) and lowest in the marine water (average 0.4 × 108 and 0.5 × 107 mL?1, respectively). Bacterial and viral counts were also several times higher during the summer than in winter. Approximately, 35% of the 141 samples were inducible in the presence of mitomycin C. The highest percentage of inducible lysogens was observed in marine waters (42%), while the lowest percentage was observed in the warmer freshwater (23%). A statistical model for the joint occurrence of lysogens and free viruses was formulated and estimated using Bayesian techniques to understand the key environmental determinants of viruses and lysogens. Our results support the existence of significant heterogeneity between the saltwater and freshwater sites. A parsimonious model that combines the two saltwater sites performs best among the specifications that were considered. Bacteria and water temperature were significant determinants of virus counts, whereas lysogen relationships are unclear. Importantly, conditional on the covariates, viruses and lysogen fractions exhibit robust negative correlation. |
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| Keywords: | lysogen virus aquatic environment Bayesian inference Markov chain Monte Carlo Tobit regression |
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