The zebra mussel, a freshwater shellfish native to Eastern Europe, has long been spreading out from its original habitats and has now reached parts of North America. There are reasons to believe that this invasion cannot be stopped and that it poses a serious threat to freshwater fish populations in all of North America.
First, the history of the zebra mussel's spread suggests that the invasion might be unstoppable. It is a prime example of an invasion made possible by human transportation. From the zebra mussel，s original habitats in Eastern Europe, ships helped spread it out along new canals built to connect Europe’s waterways. The mussel can attach itself to a ship’ s bottom or can survive in the water—called "ballast water"—that the ship needs to take on to properly balance its cargo. By the early nineteenth century, the mussel had spread to the whole of Europe. It was later carried to the east coast of North America in the ballast water of ships traveling from Europe. The way ships have spread the zebra mussel inthe past strongly suggests that the species will soon colonize all of North America.
Moreover, once zebra mussels are carried to a new habitat, theycan dominate it. They are a hardy species that does well under a variety of conditions, and they have a high rate of reproduction. Most important, however, zebra mussels often have no predators in their new habitats, and species without natural predators are likely to dominate their habitats.
Finally, zebra mussels are likely to cause a decline in the overall fish population in habitats where they become dominant. The mussels are plankton eaters, which means that they compete for food with many freshwater fish species.
Both the reading and lecture discuss zebra mussel. The reading implies that the intrusion of zebra mussel is unstoppable and it threatens the fresh water fish populations which habitat in North America. However, the professor strongly disagrees with the reading passage. Accordingly, he presents three refutations.
First of all, the reading passage mentions that invasion cannot be stopped. Yet, the lecturer severely challenges the theory by arguing that people have limited knowledge. Furthermore, he states that there are ways to prevent ship spreading this creature to new locations. Therefore, the invasion of zebra mussels can be successfully avoided actually.
Secondly, the passage suggests that as long as zebra mussels arrive at new habitat, they will be able to dominate the environment. Nevertheless, the scholar seriously contradicts the hypothesis by calling into question predator of mussels. In fact, natural predators would switch their food sources and eat zebra mussels a lot. As a result, it is unlikely for mussels to dominate their habitat.
Last but not least, the reading indicates that zebra mussels might bring about the decline of overall fish population in habitat. Once again, the speaker opposes the evidence revealed in the article. In addition, he points out that even though the fish which is plankton eater would be affected negatively by mussels, another species of fish which live in bottom layer would reverse effect because of the nutrition from zebra mussels. Apparently, the third explanation is unconvincing.
In conclusion, the professor argues against each theory in the reading. That is to say, he maintains that it is not clear that zebra mussels have great impact on fish population and habitat.
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- TPO32 90
water fish populations which habitat in North America.
Description: 'habitat' is not a verb
Definitions of habitat
noun
the natural home or environment of an animal, plant, or other organism.
wild chimps in their natural habitat
synonyms: natural environment, natural surroundings, home, domain, haunt, habitation
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another species of fish which live in bottom layer
another species of fish which lives in the bottom layer
flaws:
Don't need a conclusion paragraph. The correct pattern:
para 1: introduction
para 2: doubt 1
para 3: doubt 2
para 4: doubt 3
Attribute Value Ideal
Score: 25 in 30
Category: Very Good Excellent
No. of Grammatical Errors: 2 2
No. of Spelling Errors: 0 2
No. of Sentences: 18 12
No. of Words: 272 250
No. of Characters: 1431 1200
No. of Different Words: 162 150
Fourth Root of Number of Words: 4.061 4.2
Average Word Length: 5.261 4.6
Word Length SD: 2.607 2.4
No. of Words greater than 5 chars: 116 80
No. of Words greater than 6 chars: 100 60
No. of Words greater than 7 chars: 53 40
No. of Words greater than 8 chars: 32 20
Use of Passive Voice (%): 0 0
Avg. Sentence Length: 15.111 21.0
Sentence Length SD: 7.908 7.5
Use of Discourse Markers (%): 0.778 0.12
Sentence-Text Coherence: 0.304 0.35
Sentence-Para Coherence: 0.539 0.50
Sentence-Sentence Coherence: 0.088 0.07
Number of Paragraphs: 5 4