Nonnative Species in Aquatic Ecosystems

Which of the following is an example of chemical control of nonnative species?
a.
mowing
b.
herbicides
c.
net barriers
d.
inspections

b. herbicides

Why might it be beneficial for governments to restrict the types of plants and animals that individuals can keep as pets in a particular environment?

For many exotic pet species, if they escape or are released into the environment they have the potential to become invasive and do extensive damage to the local environment. In order to preserve the local environment for everyone, it may therefore be beneficial to restrict individuals’ rights to own exotic species.

Based on California’s experience with Caulerpa, the killer algae, explain why it is important to regulate the pet and aquarium trade.

Even species that are kept as pets and in aquariums should be regulated and tracked because their accidental release can have serious negative environmental impacts. Some owners and aquarium keepers intentionally release these species into the wild rather than destroy them, and accidental release is always a risk. Therefore, if a potentially destructive species is going to be kept as a pet or in an aquarium they should be regulated so proper safety precautions can be taken.

What factor determines when a species is considered invasive?
a.
It has positive environmental impacts.
b.
It is environmentally damaging.
c.
It spreads outside its native range.
d.
It spreads within its natural range.

b. It is environmentally damaging.

Which of the following is not a reason that nonnative species are reared outside their native ecosystems?
a.
They are commercially important.
b.
They are used to replace native species.
c.
They are used for restocking programs.
d.
None of the above

d. None of the above

Explain why the fact that invasive species did not co-evolve with the native species unbalances an ecosystem.

Because invasive species did not co-evolve with the other species of an ecosystem, they lack controls on their population, such as predators, that native species possess. As a result the population of an invasive species can grow uncontrolled and will eventually unbalance an ecosystem.

Explain why the cane toad was a failure as a biological control method in Australia.

The cane toad was introduced into Australia to control the population of sugarcane beetles. However, upon introduction, the toads did not eat the beetle, but instead began damaging local ecosystems by preying upon other organisms and poisoning most animals that tried to prey on them.

Nonnative species disrupt ecosystems by _______.
a.
increasing biodiversity
b.
preventing the spread of disease
c.
disrupting food chains
d.
increasing the populations of native species

c. disrupting food chains

As a vector for the introduction of nonnative species, why is hull fouling particularly difficult to combat?

Recreational boating and commercial shipping are an immense source of revenue and commerce around the world. Therefore, the need to protect the environment must be balanced against the needs of individuals and communities to earn a living. People who financially benefit from these industries do not want too many obstacles erected in the way of such businesses.

Since invasive species did not co-evolve with the other species in the ecosystem where they were introduced _______.
a.
they can unbalance the ecosystem
b.
they are considered a serious environmental problem
c.
they lack natural predators to help control their population
d.
all of the above

d. all of the above

The rusty crayfish is harmful to native species of crayfish because it clear cuts the bottom of waterways leaving native species without a food supply.

TRUE

Why does the aquarium trade contribute to the introduction of nonnative species?
a.
Exotic species can escape or be released into local ecosystems.
b.
Aquarium owners do not always understand how ecosystems interact.
c.
Nonnative fish are shipped worldwide for aquariums.
d.
All of the above

NOT B

Ships that use ballast water are not in danger of introducing invasive species into aquatic habitats.

FALSE

Nonnative species are only introduced unintentionally.

FALSE

Which of the following is true concerning hull fouling from commercial shipping and recreational boating?
a.
It constitutes less than half of all nonnative species introductions.
b.
The revenue brought in from these industries is relatively small.
c.
It is difficult to prevent since ship hulls begin, conduct, and end voyages in water.
d.
It is best combated by chemical treatments.

c. It is difficult to prevent since ship hulls begin, conduct, and end voyages in water.

Hull fouling is a(n) _______ introduction of nonnative species.
a.
unintentional
b.
intentional
c.
unimportant
d.
land-based

a. unintentional

Cane toads are highly successful as an invasive species in Australia because there is only one species that is believed to be able to prey on them.

TRUE

All of the following are true of the Zebra mussels found in the Great Lakes EXCEPT:

a.
Zebra mussels are having are having a negative impact on the native population of mussels in the region.

b.
They were unintentionally introduced to the Great Lakes by humans.

c.
Zebra mussels have caused a great deal of environmental damage to the area.

d.
People of the Great Lake region are benefitting from the economic advantages of having zebra mussels in the region.

d. People of the Great Lake region are benefitting from the economic advantages of having zebra mussels in the region.

Which of the following is not true about nonnative species?
a.
They can have positive impacts on an ecosystem.
b.
They can have negative impacts on an ecosystem.
c.
They can be introduced within their natural range.
d.
A nonnative species can be an invasive species.

c. They can be introduced within their natural range.

Introducing invasive species to an ecosystem results in an increase in biodiversity.

FALSE