▶ Your Answer :
The lecturer and the reading passage discuss the zebra mussel, a freshwater shellfish. The professor claims
that the invasion of the zebra mussel can be stopped now with advanced
knowledge and does not make any harmful effect. This counters the reading
passage’s claim that this invasion cannot be stopped and can create a severe
threat.
To begin with, the speaker
asserts that the invasion by human transportation can be stopped. The zebra
mussels can survive in the ballast water of the ship, which needs to take on
balance its cargo. While people filled this ballast water with fresh water in
the past, people now fill up this water with salty water, which zebra mussels
are not able to survive. Because of this, the zebra mussels cannot spread
anymore by ballast water. This contradicts one of the reading passage’s claim
that the invasion of the zebra mussel could be unstoppable.
On top of that, the speaker
claims that the zebra mussels will have a lot of predators soon in their new
habitat. Although birds do not eat the zebra mussel in the beginning, they will
be able to switch and change their food source into the zebra mussel. Because
of this, the population of the zebra mussel will decrease. This is the opposite
of the reading passage’s claim that the zebra mussel can dominate in their new
habitats.
Finally, the speaker argues
that the zebra mussels are unlikely to cause a reduction in the all fish
population in their new habitats. Some fish compete for food source with the zebra
mussel and their population will be able to decrease. However, other fish,
which live in deep lake, will get benefit from the zebra mussel by providing
nutrients. This refutes the reading passage’s claim that the zebra mussels are likely
to cause a reduction in the all fish population in their habitats.
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