Explanation:
1) The point of view of the author establishes that humans are the biggest threat to sea otters because they endanger the environment of the sea otters and don't rebuild it. Explanation: ... Humans have had a very large and negative impact on them, without doing enough efforts to fix their effects on the sea otter's habitats.
2) Humans are the biggest threat to sea otter populations. Direct conflict with humans, through shootings, fishing gear entanglements and boat strikes, take a toll on sea otters, but oil spills, pollution, disease and loss of kelp pose major threats.
3) sea otters are a keystone species, meaning their role in their environment has a greater effect than other species. As top predators, sea otters are critical to maintaining the balance of nearshore ecosystems, such as kelp forests, embayments and estuaries. Without sea otters, sea urchins can overpopulate the sea floor and devour the kelp forests that provide cover and food for many other marine animals. By maintaining healthy kelp forests, sea otters also indirectly help to reduce levels of atmospheric carbon dioxide, a prevalent greenhouse gas, as kelp absorbs and sequesters carbon.
4) Sea otters have been protected by the International Fur Seal Treaty since 1911. This treaty between U.S., Russia, Japan, and Great Britain was established to ban large-scale commercial hunting of sea otters and fur seals and to allow their populations to recover. Since then, sea otter numbers have increased.
