TOEFL integrated writing: The sea otter

The article states that environmental pollution is the most likely cause of the sea otter population decline and provides three reasons of support. However, the professor in the lecture believes that the cause is predation and she refutes each of the author’s reasons. First, the reading claims that the high levels of pollutants revealed in the water samples prove that pollution is the cause. The professor refutes this point by explaining that, if pollution was the problem, dead otters would have been found, which is not the case. Predation, on the other hand, could explain the lack of dead bodies since predators eat their preys without leaving any corps. Second, the article posits that the decline of other sea mammals is another reason to believe that pollution is the problem, because it can affect an entire ecosystem. According to the author, only orcas could have the same effect, but they prefer to hunt bigger preys. However, the professor says that these preys are no longer available due to the human hunting and, as a result, the orcas have begun to eat smaller sea mammals. Third, the reading says that ocean currents create different concentrations of pollutants, which could explain the uneven pattern of otter decline. The professor opposes to this point by stating that this pattern is better explicated by the predation theory. She says that orcas cannot access all locations because of their size and that is why in shallow and rocky places, which are not accessible to these predators, there has not been any otter decline.