Extended Data Fig. 9: Seasonal and interannual infection dynamics.
From: Viruses affect picocyanobacterial abundance and biogeography in the North Pacific Ocean
(a) Seasonally increasing infection levels for Prochlorococcus (left) and Synechococcus (right) from cruises in March 2015, April 2019, April 2016, June 2017 (this study), and July-August 201539 in the subtropical gyre. Boxes show the median, 1st quartile, 3rd quartile, minimum and maximum are shown by box-and-whisker plots. Individual data points are shown to the left of each box. (b) Oceanic Niño Indices for 2014–2019 from the National Oceanographic and Atmospheric Administration89. Warm phases (>0.5) are indicated by orange, neutral phases (−0.5–0.5) are indicated by grey, and cool phases (<−0.5) are indicated by blue. Red boxes indicate the timing of the March 2015, April 2016, July 2017 and April 2019 cruises in this study. A record marine heatwave occurred in 2015 and 2016 when infection levels were low. The 2017 transects which had high viral infection occurred during a cool phase of the El Niño Oscillation. When El Niño conditions and the warm temperature anomaly returned in 2019, infection levels were low in the subtropical gyre in April, consistent with both seasonal and climatic hypotheses.
