TPO 26-The treat of zebra mussel

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The reading and the listening are contradicting with each other, in terms of invasion of the zebra mussel. The author of the reading states that this invasion cannot be prevented and also it would create a serious threat to freshwater fish populations in North America. However, the lecturer casts doubt about the claim and negates all the theories presented in the passage.
First of all, according to the article, the invasion of the mussel is possible due to human transportation where the mussels can attach with the bottom of the ship and spread all over North America. On the other hand, the speaker negates the argument and mentions about the mussels that it could not be stoppable in past but nowadays, with the help knowledge, it is possible to stop the mussels spreading all over the North American ocean. Furthermore, the describes that the ship which carried the ballast water with its bottom, it can be dumped into the ocean just beside the ocean, and this way, the mussels cannot survive in the saltwater.
Secondly, the author states that zebra mussels have been dominating in the new habitats since there are no predators who can eat them. Thus, it will create a big threat to ocean fish who lives there. Although the lecturer undermines this by asserting that there are many birds who are in search of the food in that place. As a result, whenever the bird would find the new creature living in that habitat, they will start eating them. As a result, the mussels cannot be overcrowded in that place. Hence, this idea is not acceptable.
Finally, it is mentioned in the paragraph that since the mussels are plankton eater, the fish would need to compete for the plankton plant with the mussels and thereby, the population of fish might be declined over the time. On the contrary, here also, the lecturer refutes the idea and describes it is true that some fish population might be decreased, although the mussels have a positive effect on the fish population who lives at the bottom of the ocean because they get food in form of nutrient from the zebra mussels. Therefore, the final idea is also true and acceptable.

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