Seasonal patterns of abundance of viruses and bacteria in a Northeast Ohio (USA) stream

Abstract

Bacteria and virus-like particles (VLP) were enumerated in water, leaf, and sediment samples collected seasonally from the West Branch of the Mahoning River (OH, USA). In water, bacteria ranged from 9.37-46.5 x 10 5 cells per ml, VLP were 1.97-5.68 x 10 6 per ml, and virus: bacteria ratios (VBRs) were 0.42-3.49. In leaf samples, bacteria were 2.09-49.5 x 10 8 per g, VLP were 4.81-21.8 x 10 8 per g, and VBRs were 0.40-2.55. In sediment samples, bacteria were 1.85-7.07 x 10 7 per g, VLP were 4.71-8.91 x 10 6 per g and VBRs were 0.09-0.45. Bacterial numbers in water were comparable to previous studies and were highest in spring. Occasionally, VLP numbers in water were significantly higher than bacterial counts. In contrast, VLP numbers were often lower than bacterial numbers in leaf and sediment samples and did not vary as much among dates. Only in the leaf samples was there a significant linear relationship between VLP and bacterial abundance based on regression analysis. Compared to lakes and marine systems, VLP abundance was low in this system and a virus-bacteria relationship was generally not apparent. In lotic ecosystems, rapid changes in environmental conditions may result in a less direct virus-bacteria connection than in other aquatic ecosystems.