1、TPO 10The lecture and reading passage both talked about two of the possible hypotheses for the extinction of sea otters. While the article was in favor of the pollution theory, the lecturer doubted its validity for the following reasons.To begin with, the first piece of evidence that sea otters dimi
2、nished due to environmental pollution was its known sources along the Alaska coast. If that was the case then dead sea otters ought to be found along the coast. However, as the lecturere pointed out, investigations discovered no sea otter corpses along the shore. This fact could perfectly be explain
3、ed by the predation theory because if sea otters were hunted by predators and eaten immediately it would not be suprising when no corpses were found.Moreover, the reading mentioned that since the number of other sea mammals like sea liones were decreasing as well, the cause could not be predation as
4、 the only candidate, orcas, usually feed on large mammals. Nevertheless, the lecture stated that given the absence of larger pray it was likely for orcas to change their diet from whales to small sea mammals including sea otters.Lastly, regarding the inconsistent pattern of sea otter decline, where
5、in some areas the number of sea otters remained constant whlie in others that was not the case, the author of the passage argued that pollution hypothesis could explain this phenomenon whereas it could be better explained by the predation hypothesis according to the lecture. Statistics showed that in locations with prevalent orcas activites sea otters suffered great loss in population. In contrast, in shallow areas where orcas could not acess the sea otter population did not decline.
