The material discusses the invasion of zebra mussels. While the reading mentions that there are no ways to control its invasion. On the other hand, the listening challenges this and states that zebra mussels' spreading out could be stopped.
First, the writer contends that the invansion might be unstopped because it happens becasue of its attachment to the balance water of
the ships. On the contrary, the lecturer refutes this and mentions that zebra mussels' spreading could not be done in the past given that there was not enough knowledge. The professor adds that it could be done through stoping ships carrying them. The listening explains that zebra mussels travel across the ocean through the fresh balance water, so if ships empty out this fresh water and fill with ocean's water, the salt will kill zebra mussels.
Second, the reading assumes that zebra mussels are dominate becasue they have no predators. According to the listening, the professer points out that zebra mussels have no predators just in the beginning. The lecturer adds that aquatic birds can recognize that there is a new food, so they could swith out their food. The professor says that birds can eat a lot of mussels.
Third, the author mentions that zebra mussels cause a decline in the overall fish populations. Conversely, the professor opposes this and states that zeb ra mussels have a negative impact on some fishs, but they have a positive impact on others. The lecturer says that because of zebra mussels the buttom fishs are increased.
The material discusses the invasion of zebra
mussels
.
While
the reading mentions that there are no ways to control its invasion.
On the other hand
, the listening challenges this and states that zebra mussels' spreading out could be
stopped
.
First
, the writer contends that the
invansion
might
be unstopped
because
it happens
becasue
of its attachment to the balance
water
of
the
ships.
On the contrary
, the lecturer refutes this and mentions that zebra mussels' spreading could not
be done
in the past
given
that there was not
enough
knowledge. The professor
adds
that it could
be done
through
stoping
ships carrying them. The listening
explains
that zebra
mussels
travel across the ocean through the fresh balance
water
,
so
if ships empty out this fresh
water
and fill with ocean's
water
, the salt will kill zebra mussels.
Second, the reading assumes that zebra
mussels
are
dominate
becasue
they have no predators. According to the listening, the
professer
points out that zebra
mussels
have no predators
just
in the beginning. The lecturer
adds
that aquatic birds can recognize that there is a new food,
so
they could
swith
out their food. The professor says that birds can eat
a lot of
mussels.
Third, the author mentions that zebra
mussels
cause a decline in the
overall
fish populations.
Conversely
, the professor opposes this and states that
zeb ra
mussels
have a
negative
impact on
some
fishs
,
but
they have a
positive
impact on others. The lecturer says that
because
of zebra
mussels
the
buttom
fishs
are increased
.