Module 3

Native mussels in the Great Lakes helped to maintain water clarity by

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The round goby is considered a generalist species because

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Features of zebra mussels that enabled them to be such successful invaders include

-the ability of females to produce so many eggs -a lack of native predators in the Great Lakes -their high filtration rate - their ability to reproduce at a young age

In a sense, it could be said that the Clean Water Act had its origins in

Cuyahoga river

Another ballast hitch-hiker, the Eurasian ruffe, became a very successful invader in the Great Lakes, largely due to

an extremely high reproductive rate

Botulism-causing bacteria spread up the food chain after

being ingested by invasive mussels B. gobies ate toxic mussels C. birds consumed toxic gobies

What is the process by which toxins reach higher levels in species that are higher up the food chain?

bioaccumulation

The EPA exempted the discharge of ballast water from the Clean Water Act

even though they did not have Congressional approval to do so because they thought it was relatively harmless because doing so would reduce administrative costs

Cladaphora is a green algae that is native to all the Great Lakes except Superior, and became a nuisance in the 1960s due to

excess phosphorus inputs adverse impacts of human activities

The zebra mussel, quagga mussel, and round goby

first appeared in North America in or near Lake St. Clair have their native range in the Black and/or Caspian Seas likely reached the Great Lakes in the ballast of a freighter

Quagga mussels eventually outnumbered zebra mussels by a huge margin because the former

have an even higher rate of reproduction can tolerate much deeper water don't need a hard surface to adhere to

Ballast serves a key function on freighters because

heavy reliable free and stability

Zebra mussels impact native mussels directly

inhibiting their ability to open their shells

The round goby is a highly successful invasive species because

it is very aggressive

As described in Silent Invaders, zebra mussels have an inhalant siphon and an exhalant siphone. What is removed in between?

large algae

Even though zebra mussels can only move about 14" an hour using their 'foot,' they can rapidly reach new locations because

offspring are covered with hairs that help them to catch currents

Detractors of the St. Lawrence Seaway believed

that it would ruin the business of U.S. ports on the eastern seaboard

A key problem with the St. Lawrence Seaway was

the 9-month shipping season that the locks and channels were too small

According to the film The St. Lawrence Seaway System,

the Seaway was one of the top 10 public works of the 20th century all cargo is tracked as it makes its way through the system tourists from all over the world sail through the Seaway on luxury cruise ships

In addition to ballast water, round gobies are spreading in the Great Lakes region because

they are used as bait to catch larger fish

The zebra mussel could not have 'walked' across the Atlantic Ocean to reach the Great Lakes, even over many generations, because

they could not have survived the ocean's salinity or depth

One way that gobies can gain a numerical advantage on native fish is that

they spawn up to three times per summer they are voracious egg eaters they drive other fish from their spawning beds

The St. Lawrence Seaway was constructed

to allow ocean-going freighters access to the Great Lakes because the U.S. President saw strategic value there during the cold war with the USSR

In the film The St. Lawrence Seaway System, the proposed way to get around the fact that the locks and channels were too small for transoceanic ships was

to unload cargo and put it on smaller ships

The diet of the round goby includes

zooplankton young zebra and quagga mussels young of larger fish eggs of other fish