Warming advances virus population dynamics in a temperate freshwater plankton community

Thijs Frenken,Ellen Van Donk,Dedmer B Van De Waal,Edwin T H M Peeters,Sarian Kosten,Susanne Stephan,Corina P D Brussaard,Lisette N De Senerpont Domis,Garabet Kazanjian,Ralf Aben,Mandy Velthuis,Sabine Hilt

doi:10.1002/lol2.10160

Abstract

Viruses are important drivers in the cycling of carbon and nutrients in aquatic ecosystems. Since viruses are obligate parasites, their production completely depends on growth and metabolism of hosts and therefore can be affected by climate change. Here, we investigated if warming (+4°C) can change the outcome of viral infections in a natural freshwater virus community over a 5‐month period in a mesocosm experiment. We monitored dynamics of viruses and potential hosts. Results show that warming significantly advanced the early summer peak of the virus community by 24 d, but neither affected viral peak abundances nor time‐integrated number of viruses present. Our results demonstrate that warming advances the timing of viruses in a natural community. Although warming may not necessarily result in a stronger viral control of bacterial and phytoplankton communities, our results suggest it can alter host population dynamics through advanced timing of infections, and thus timing of carbon and nutrient recycling.

Highlights

Viruses are important drivers in the cycling of carbon and nutrients in aquatic ecosystems
Warming resulted in a lower density of phytoplankton cells (Velthuis et al 2017), as well as a reduced seston chlorophyll a (Chl a) concentration that reached maximum values of 32.6 Æ 3.5 and 27.5 Æ 4.8 μg L−1 in the control and warm treatment, respectively (Fig. 2C; Supporting Information Tables S2, S3)
Heterotrophic bacterial abundances were at least two orders of magnitude higher (Fig. 2A), and likely served as the main viral hosts, contributing most to the actual number of viruses produced. This is exemplified by the total virus-to-bacteria ratio (VBR, Supporting Information Fig. S2), ranging on average between 20 and 85, which is in the typical range for freshwater systems (Maranger and Bird 1995; Wommack and Colwell 2000)