Fig 1. Sampling locations and study site geography.
The numbered white circles show the 12 sample sites. The red squares show the locations of the five shipping terminals. The rivers and estuary are shown in blue. High-capacity highways are plotted as wide, light grey lines, while the greater highway network is in black. The background shading describes the average interpolated Breteau Index score: 0–2 (dark grey); 2–4 (grey); 4–6 (light grey). The underlying road network is derived from the Chinese "Highways" shapefile made available by MapCruzin.com and OpenStreetMap.org under the Open Database License [https://opendatacommons.org/licenses/odbl/1.0/].
