Great Lakes maritime industry and environmentalists team up to keep ‘critters’ from hitching rides in ships’ ballast waterHow safe is safe? How can we keep aquatic invasive species out of ballast water & out of the Great Lakes? How many organisms discharged from a ship’s ballast tanks are enough to spark an invasion? What ballast water treatment methods would best manage those threats ahead of time? Are microbes – the smallest of organisms (e.g. bacteria and viruses) – a concern?