Microbial hitchhikers: dynamics of bacterial populations in ballast water during a trans-Pacific voyage of a bulk carrier

Abstract

Bacterial abundance, population dynamics and related environmental parameters were determined in ballast water during a trans- Pacific voyage from Japan to the west coast of Canada. Water samples were collected from four ballast tanks, two of which underwent mid-ocean exchange (MOE) and two that remained unexchanged (control). Bacterial abundances in the unexchanged tanks increased from ~6.4×10 8 cells/L on Day 0 to 1.8×10 9 cells/L on Day 7, whereas in MOE tanks, abundances increased from