integrated. tpo 26

The reding states that the zebra mussel, a fresh water shellfish native to Eastern Europe, has long been spreading out from it's origional habitats and has now reached parts of North America. And it says there are reasons to believe that this invasion cannot be stopped and that it poses a serious threat to fresh water fish populations in all of North America.conversely the professor says that, the zebra mussel will not cause threat to fish populations and he refutes each claim in the reading.

First, the reading states that, the history of the zebra mussel's spread suggests that the invasion might be unstoppable. But the professor says that, may be that was in the past, because there had no enough knowledge. for example, Zebra mussel crosses ocean and balst water in Europe empty in Northern United states when arrive. Without zebra mussel , ships cannot empty and refill the ocean.

Second, the reading says that,once zebra mussels are carried to a new habitat, they can dominate it. However the professor says that, it is true but only in the beginning. In Europe later and sooner there are birds eat a lot of zebra mussels as a result they cannot dominate their habitat.

Third, the reading says that, zebra mussels are likely to cause a decline in the overall fish population in habitat where they become dominant. But the professor says that over all fish population will decline because of the negative impression of the zebra mussels on them, but they have a positive impression on other fish population. And when the general nutrient increase, the fish number at the bottom will increase.