TPO 10 - Integrated task

The article and the lecture are about sea otters which are a small type of mammal living along the western coast of USA. The article states that sea otter populations'declining may be related to increased pollution. The lecture cast doubts on the claims made in the article. Indeed, the lecturer sustains that predators'attack is the most probable root cause of sea otters'decline.

To begin with, the author of the reading points out that pollution is a consistent hypothesis as it could explain the uneven pattern of otter decline. This point is challenged by the lecturer, who argues that the pollution theory can't explain the change in the ecosystem occurred along the western coast. He says that the absence of sea otters'rests is the proof of concept that the pollution theory is wrong. He adducts two main reasons to support the predators hypothesis.

The first reason is that, chemical pollution produced by industrial chemicals would imply sea otters's death although no skeleton of these animals has been recovered. In addition, the lecturer suggests that the decline of other animals such as seals and sea lions is not a coincidence. He believes that this is a result of the predators'theory.

As second reason, he mentions that as whales are also disappearing due to human hunters, the ecosystem experienced a slight modification and as a result of this, orcas started to eat sea otters as well as other sea mammals. All together, these facts support the orca predation theory as the most likely cause of sea otters decline.