What’s coming eventually comes: a follow-up on an invader’s spread by the world’s largest water diversion in China

Abstract

Zhan et al. (Biological Invasions, 2015, 17:3073–3080) stressed that China’s South-to-North Water Transfer Project (SNWTP)—the world’s largest constructed water diversion—could create an invasion highway by facilitating spread of non-native species, including invasive golden mussel Limnoperna fortunei. However, most available literature indicated that golden mussels could not survive the cold winter in Northern China. We proposed that phenotypic plasticity and rapid environmental adaptation, combined with relatively high water temperature derived from wastewater treatment plant effluents and a large potential inoculum continuously transported from southern source populations, could jointly contribute to golden mussel spread into northern locations. We conducted surveillance for the species both before and after the waterway was opened in late 2014 in the diversion destination—Beijing. While all surveys in the whole area were negative between 2014 and 2018, we detected rapid geographical expansions in 2019–2021 across multiple waterbodies based on traditional field surveys and environmental DNA (eDNA)-based methods. Surprisingly, we subsequently observed populations that had successfully survived a cold winter in Beijing. The SNWTP may facilitate further spread of cold-adapted populations, placing high-latitude areas at risk. This case study highlights the need for robust scientific assessment and management to predict and mitigate non-native species’ distributional changes that may accompany large-scale hydraulic projects.