4 Introduction Hidden Below The ship left port It headed for the United States It was not carrying many goods It had a light load But it was loaded with something else Stowaways Invisible stowaways Harmful stowaways And no one knew they were there until it was too late
6 Chapter 1 Too Small to See It was 1988. A cargo ship set sail It was from Russia or Ukraine It traveled from the Black Sea to the Great Lakes It carried goods for the US The ship also carried something else Tiny young zebra mussels The larvae are called veligers You can't see them without a microscope The veligers rode in the bottom of the ship They were sucked up in the ballast water in Russia This water helps a ship keep its balance in the ocean The ship reached the US It traveled down the St. Lawrence Seaway This is between Canada and the US The ship dumped the water into the Great Lakes Millions of invisible veligers floated into their new home
BALANCING BOATS Ships use water from the ocean to give them weight It helps them balance in wavy waters It helps them balance if they do not have big loads Ships pump this water into their ballast tanks They pump it out when their trip is done Ballast water spreads invasive species 7
