Figure 1

The map of sample sites in this study. The map of the Mekong river basin (Left part of Fig. 1) was finished by Shannon1 (https://commons.wikimedia.org/w/index.php?curid=65845951). We removed the cities from the origin map and increased font sizes of scale. This image is under the CC BY-SA 4.0 license (https://creativecommons.org/licenses/by-sa/4.0/).