Part Six, Issue 22

1. Part Six, Issue 22 Illegal Immigration: Ballast Water and Exotic Species

2. Objectives After reading the assigned chapter and reviewing the materials presented the students will be able to understand: • What are exotic species? • How are they able to cross oceans? • What threats do they pose to ecosystems?

3. Introduction • Ballast discharges from freighters are the major pathway for exotic aquatic organisms such as Chinese mitten crab, green crab, and Asian clam which threaten native marine life in San Francisco Bay and as far north as Washington state. • The invaders are driving out native crabs and clams and threatening local oysters – even burrowing into and weakening flood control levees which could result in huge losses from property damage during floods. • Since the issue involves interstate and international commerce, environmental groups asked the EPA to regulate freight ballast water discharges under the Clean Water Act.

4. Illegal Immigrants • The aim of the exotic species is not to take over an estuary or clog a factory’s water pipes, but to simply survive and reproduce. • Successful invasive species usually have the characteristics: They are hardy, indicated by their surviving inside a ship for perhaps thousands of miles. They are aggressive, with the capacity to outcompete native species. They are prolific breeders and can quickly take advantage of any new opportunity. They disperse rapidly. • Invasive species can damage the ecosystem by: outcompeting native species, introducing parasites and/or diseases, preying on native species, and adversely altering habitat.

5. Ballast Water • Most invasive species are brought to new shores by ballast water of ships. • Ballast water is carried by ships in special tanks to provide stability and optimize steering and propulsion. • As a result, a myriad of organisms is transported around the world within the ballast water of ships and is released.

6. Invasive Species • More than 90% of vessels arriving at Chesapeake Bay ports carried live organisms in ballast water, including, but not limited to, barnacles, clams, mussels, copepods, diatoms, and juvenile fish. • Chinese mitten crabs dig burrows that can significantly weaken levees (embankments to prevent flooding) in regions that are prone to severe floods. • The European green crab is an aggressive predator preferring clams to oysters. • Washington oyster farmers had to abandon habitat overrun by oyster drill. • R. venosa whelk, another invasive species in the Chesapeake Bay, feeds on oysters, soft clams or mussels. The whelk’s known predator is the octopus, but there are no octopus in Chesapeake Bay. • Zebra mussel, a native of Eastern Europe, can destroy entire colonies of native mussel . Since 1989, power plants, water utilities, industrial facilities and navigation lock and dam operators have spent more than $70 million to try and control zebra mussel infestation because they attach to the inside of pipes.

7. Summary • Ballast discharges from freighters are the major pathway for exotic aquatic organisms such as Chinese mitten crab, green crab, and Asian clam which threaten native marine life in San Francisco Bay and as far north as Washington state. • Successful invasive species usually have the characteristics: They are hardy, indicated by their surviving inside a ship for perhaps thousands of miles. They are aggressive, with the capacity to outcompete native species. They are prolific breeders and can quickly take advantage of any new opportunity. They disperse rapidly. • Invasive species can damage the ecosystem by: outcompeting native species, introducing parasites and/or diseases, preying on native species, and adversely altering habitat. • Ballast water is carried by ships in special tanks to provide stability and optimize steering and propulsion. • Zebra mussel, a native of Eastern Europe, can destroy entire colonies of native mussel . Since 1989, power plants, water utilities, industrial facilities and navigation lock and dam operators have spent more than $70 million to try and control zebra mussel infestation because they attach to the inside of pipes.

8. Home Work • 1. What are the major pathways for exotic aquatic organisms to threaten native marine life? • 2. What are the characteristics of successful invasive species? • 3. How can invasive species damage the ecosystem?