Zebra Mussels

The reading and the lecture are both about zebra mussels. The reading claims that the presence threatens the freshwater fish population in all North America and provides three reasons. Whereas, the lecturer refutes each point by providing reasons and examples.

First, the article states that zebra mussel's invasion has been made possible by human transportation, ships. While the professor says that people could not prevent the invasion in the past. But now, there are ways to keep them out of North America. Furthermore, he suggest that if the ship depletes the water in the ocean and refill, the salt water will kill the zebra mussels.

Second, the author of the reading contends that zebra mussels can dominate the new habitat because they have
no predators. However, the professor opposes this statement. According to the professor, only in the beginning they have no predators, but with the passage of time, birds change their food habits and start eating them; birds can eat many of them.

Third, the reading mentions that when the zebra mussels dominate the habitat, they cause a decline in the overall fish population. The professor agrees with the overal decline, but he insists that the bottom fish community will strengthen due to the zebra mussels generating nutrients which they have.