TPO-26 - Integrated Writing Task The zebra mussel, a freshwater shellfish native to Eastern Europe, has long been spreading out from its original habitats and has now reached parts of North America. There are reasons to believe that this invasion cannot b

In this set of materials, the reading introduces three reasons to support the idea that Zebra mussel population in North America can't be controlled. However, the professor raises questions on the ideas and presents some evidence to refute them all and shows how to handle this problem. First, the author of the article states that human transportation via ships will bring more Zebra mussels to the North America. On the contrary, the speaker refute this point by saying that in the past people didn't have sufficient knowledge, therefore, they traveled many zebra mussels. But, nowadays, people find some methods to prevent bringing zebra mussels with themselves, such as washing boat with Ocean's water which can kill these zebra mussels. Furthermore, the reading passage posits that zebra mussels have a high reproduction ratio without serious predator, moreover, they can adapt to new environments. Conversely, the professor, asserts that at the beginning of their arrival they don't have much predators but when they dominate in the environment and consume the available food sources, some birds which can't find food would hunt these zebra mussels. Thus, zebra mussels wouldn't and can't dominant for a long time in the area. Finally, the professor wasn't convinced that fish population will decrease due to presence of the zebra mussels, which is the last mentioned reason by the author of the article. He admits that zebra mussels have some negative effects, nevertheless, he highlights that these zebra mussels have positive effects too. Providing food for bottom eating fishes is one of zebra mussels' advantages that professor touches on.