Effects of voyage routing on the survival of microbes in ballast water

► This study examines the use of patterns of variation in voyage routing water temperature to lighten the burden of on board ballast water management. ► Total bacterial counts decreased during the first six days of the voyage regardless of trends in temperature variation. ► The ability of temperature to maintain bacterial counts at a certain level was obvious when temperature continuously decreased to less than 15 °C, or rose within the same range. ► Variations in water temperature may assist ballast water management in some cases.