integrated. tpo 26

This set of the material in the both reading and lecture is about the zebra mussel. The reading provides three pieces of evidence indicating that introducing this species from Eastern Europe to the North America has caused serious threat to the fish population in the United States. The lecturer, nonetheless, refutes the author's claims by offering three counterclaims.

First, the reading points out that if transporation system did not stop, such invasion would be serious damage to the fish population. The lecturer, however, takes this view that in the past, people were not able to deal with this invasion due to lack of knowledge. While today, if people replace fresh water of ships with salty water, such domination will reduce since the zebra mussel cannot survive in salty water.

Second, the passage brings up this view that since the zebra mussels have no serious predator, they are most likely to invade a habitat. This will be intensified by their high speed reproduction rate. In contrast, the professor disputes this point by arguing that when many local aquatic birds face limited food sources, they will change their eating habits to the zebra mussels.

Third, the reading sheds light on this point that rapid domination of the zebra mussels in habitats has resulted in a critical reduction in fish population which depends on plankton, the same food source. The professor casts doubt on this point due to the fact that although zebra mussels feed on plankton and consequently those fish which rely on plankton are facing limited food access, there are some fish at the sea bottom that benefit from the presence of zebra mussels by producing nutrition at the bottom of see.