Sea otters are a small mammal that lives in the waters along North America's west coast from California to Alaska. A few years ago some of the sea otter populations off of the Alaskan coast started to decline rapidly and raised several concerns because of their important role in the coastal ecosystem. Experts began investigating and came up with two possible explanations. One explanation was environmental pollution and the second was attacks by predators. At first it seemed as if the pollution was the most likely cause for the population decline.
One reason pollution was more likely was because of the known pollution sources along the Alaskan coast such as oil rigs. Also water samples taken in the area showed increased levels of chemicals that could decrease the otters' immune systems and indirectly result in their deaths. Another thing that pointed to pollution as the culprit was the decline of other sea mammals such as seals in the same areas. This indicated that whatever was affecting the otters was also affecting the other sea mammals. Environmental pollution usually affects an entire ecosystem instead of just one species.
Only predators that occurred in a large area, such as orcas (a large predatory whale), could cause the same effect, but they usually hunt larger prey. Finally, scientists believed the pollution hypothesis would also explain the uneven pattern of otter decline. In some Alaskan locations the otter population declined greatly while other populations remained stable. Some experts suggested this could be explained by ocean currents, or other environmental factor, might have created uneven concentrations of pollutants along the coast.
You have twenty minutes to answer the following question. You can refer to the article as you write your essay. You may not listen to the lecture again.
Summarize the points made in the lecture, being sure to explain how they cast doubt on the solutions presented in the reading passage.
Both the reading passage and the lecture talk about the declined population of sea otters. The author in the reading passage mentions environmental pollution is the reason behind the decline in the number of sea otters; however, in the lecture, the attacks by predators are mentioned as a cause behind it. So, basically, these two contradicts. Firstly, the author mentions the pollution sources along the Alaskan coast which causes a decay of the population. However, the lecturer argues that the predators hunt otters and ate all of those - it is right away responsible here. Secondly, the reading passage mentions that environmental pollution affects otters most since other sea mammals are dead. The lecturer, on the other hand, argues that the decline of other sea mammal populations, such as orcas, is also caused by the attacks of predators. Their predators used to live on the whale, but human hunters hunted these. As a result, they lost the main source of food. Later, they switched their prey to smaller mammals like orcas. Thirdly, the reading passage mentions that pollution hypotheses can explain the uneven pattern of the decline in the number of otters. The lecturer contradicts it and argues it in terms of the attacks of predators. The lecturer says that the population of sea otters is not large in the location where orcas or the predators flourished. So, the population of sea otters is more stable where orcas cannot inhabit. To conclude, the reading passage and the lecture agree nowhere and both contradict almost all points.
