In the modern times, Both the author and the lecturer speak about the zebra mussel species and their migration to some parts of North America; but in terms of how it has affected their new habitat, the reading passage and the listening are at odds with each other. The author proposes that the zebra mussel has had a negative impact on their new habitat, according to an unstoppable invasion and aggressive population. The speaker, however, refutes the author's point of view by presenting other evidence. As the author states, the zebra mussel's migration has been unstoppable by virtue of human activity. In fact, the zebra mussels attach to the bottom of ships that cross the man-made canals and waterways, and they can survive in the "ballast water" and reach North America. On the other hand, the speaker argues that ships can empty their ballast water and refill it with ocean water, which is salty and lethal for the zebra mussel resulting in stopping their migration. …show more content…
In addition, they do not have natural predators to control their populations. In contrast, according to the speaker, some aquatic birds have changed their habits and manage to eat a number of the zebra mussels in their habitat leading to restrict their population. Finally, contrary to the belief in the reading passage that the zebra mussel eats plankton, the main food source of fresh water species, and aggressively competes with other marine animals, the speaker believes that the zebra mussel may have some negative impact on the population of any species, but it has other positive ones. For instance, the zebra mussel can generate some nutrients that are convenient food sources for other species like bottom fish which can increase their population