Potential effects of LNG trade shift on transfer of ballast water and biota by ships.

As the US natural gas surplus grows, so does the prospect of establishing new trade partnerships with buyers abroad, a process that has major consequences for global ship movement and ballast water delivery. Since US annual imports of liquefied natural gas (LNG) peaked in 2004-2007, the country is rapidly transitioning from net importer to net exporter of LNG. Combining multiple datasets, we estimated changes in the associated flux of ships' ballast water to the US during 2015-2040, using existing scenarios for projected exports of domestic LNG by ships. Our analysis of the current market (2015) scenario predicts an approximate 90-fold annual increase in LNG-related ballast water discharge to the US by 2040 (42millionm3 ), with the potential to be even greater under high oil prices. We also described changes in geographic connectivity related to trade direction. These findings highlight how 21st century global energy markets could dramatically alter opportunities for seaborne introductions and invasions by nonnative species.