The material discusses the reasons of Steller's sea cow extinction. While the reading suggests three causes of this extinction, the listening challenges all these causes that outlined in the reading passage.
First, the author states that native Siberian overhunted sea cows because they were a good source of food in a harsh environment. On the other hand, the professor opposes this and points out that sea cows were a massive creature, one of them was nine-meter-long and ten tons weight. The lecturer adds that a couple of sea cows could feed Siberian people for a month. in addition to that, the Siberian population was not very large, so they did not need to hunt a lot of sea cows. The speaker says that native Siberian could not take sea cows to the point of extinction.
Second, the writer mentions that ecosystem disturbances caused the reduction of kelp which was the main food source of sea cows. On the contrary, the professor refutes that and posits that if the ecosystem changed, it might cause a decline in other marines, such as whales. The lecturer explains that there was not a report of whales' decline. According to the lecture, there was no indication of broadening ecosystem disturbances, so kelps were enough, and sea cows did not have any experience of food shortage.
Third, the reading cites that European fir traders had weapons that allowed them to hunt sea cows quickly, so they hunted the last sea cows. Conversely, the professor contradicts this and brings up that sea cows extinct soon after the European arrival. The lecturer adds that when European fur traders arrived, the sea cows were already declined. The sea cows started to decline a hundred years before Europeans' arrival. The professor concludes that it was supposed to be another reason that responsible for this decline.
The material discusses the reasons of
Steller
's
sea
cow
extinction. While the reading suggests three causes of this extinction, the listening challenges all these causes that outlined in the reading passage.
First
, the author states that native Siberian
overhunted
sea
cows
because
they were a
good
source of food in a harsh environment.
On the other hand
, the
professor
opposes this and points out that
sea
cows
were a massive creature, one of them was nine-meter-long and ten tons weight. The lecturer
adds
that a couple of
sea
cows
could feed Siberian
people
for a month.
in
addition to that, the Siberian population was not
very
large,
so
they did not need to hunt
a lot of
sea
cows
. The speaker says that native Siberian could not take
sea
cows
to the point of extinction.
Second, the writer mentions that ecosystem disturbances caused the reduction of kelp which was the main food source of
sea
cows
.
On the contrary
, the
professor
refutes that and posits that if the ecosystem
changed
, it might cause a
decline
in other marines, such as whales. The lecturer
explains
that there was not a report of whales'
decline
. According to the lecture, there was no indication of broadening ecosystem disturbances,
so
kelps
were
enough
, and
sea
cows
did not have any experience of food shortage.
Third, the reading cites that European fir traders had weapons that
allowed
them to hunt
sea
cows
quickly
,
so
they hunted the last
sea
cows
.
Conversely
, the
professor
contradicts this and brings up that
sea
cows
extinct
soon
after the European arrival. The lecturer
adds
that when European fur traders arrived, the
sea
cows
were already declined. The
sea
cows
started
to
decline
a hundred years
before
Europeans' arrival.
The
professor
concludes that it
was supposed
to be another reason that responsible for this
decline
.