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 in the past strongly suggests that the species will soon colonize all of North America.
Moreover, once zebra mussels are carried to a new habitat, they can 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.
The reading and listening are talking about whether the zebra mussel's invasion can be stop or not, and whether they are threat or not to North America's local fish. The reading part suggests three pieces of evidence to prove it. However, the professor says there are way to control the zebra mussel, and the zebra mussel maybe not that threat the local animals.
First, the reading part says the history of the zebra mussels' spread indicates that they are unstoppable. However, the professor says they cannot be stopped due to the past people have no knowledge. Ballast water is the approch that the zebra mussel spread through. Today's ship can fill the tank with ocean water, which can kill the zebra mussel.
Second, the reading part says the zebra mussel are hardy species with a high rate of reproduction, which ability allows them to dominate the new habitat. However, the professor asserts even the zebra mussel is highly reproductive species. When there population goes up, the native aquatic birds will notice them and eat them a lot, which preventing them to dominate the new habitat.
Finally, the reading parts suggests the zebra mussel will eat the plankton, which decreases food for local fish. The professor says that it will have some negative affect to some fish. However, it will increase some fish. Nutrition fall to the bottom of water and the bottom fish poplulation even increases.
Transition Words or Phrases used:
finally, first, however, may, second, so, talking about
Attributes: Values AverageValues Percentages(Values/AverageValues)% => Comments
Performance on Part of Speech:
To be verbs : 9.0 10.4613686534 86% => OK
Auxiliary verbs: 8.0 5.04856512141 158% => OK
Conjunction : 7.0 7.30242825607 96% => OK
Relative clauses : 9.0 12.0772626932 75% => More relative clauses wanted.
Pronoun: 14.0 22.412803532 62% => OK
Preposition: 18.0 30.3222958057 59% => More preposition wanted.
Nominalization: 5.0 5.01324503311 100% => OK
Performance on vocabulary words:
No of characters: 1175.0 1373.03311258 86% => OK
No of words: 236.0 270.72406181 87% => More content wanted.
Chars per words: 4.97881355932 5.08290768461 98% => OK
Fourth root words length: 3.91947592106 4.04702891845 97% => OK
Word Length SD: 2.25660558021 2.5805825403 87% => OK
Unique words: 118.0 145.348785872 81% => More unique words wanted.
Unique words percentage: 0.5 0.540411800872 93% => More unique words wanted or less content wanted.
syllable_count: 353.7 419.366225166 84% => OK
avg_syllables_per_word: 1.5 1.55342163355 97% => OK
A sentence (or a clause, phrase) starts by:
Pronoun: 1.0 3.25607064018 31% => OK
Article: 10.0 8.23620309051 121% => OK
Subordination: 1.0 1.25165562914 80% => OK
Conjunction: 2.0 1.51434878587 132% => OK
Preposition: 0.0 2.5761589404 0% => More preposition wanted as sentence beginning.
Performance on sentences:
How many sentences: 14.0 13.0662251656 107% => OK
Sentence length: 16.0 21.2450331126 75% => The Avg. Sentence Length is relatively short.
Sentence length SD: 36.0663362742 49.2860985944 73% => OK
Chars per sentence: 83.9285714286 110.228320801 76% => OK
Words per sentence: 16.8571428571 21.698381199 78% => OK
Discourse Markers: 3.92857142857 7.06452816374 56% => More transition words/phrases wanted.
Paragraphs: 4.0 4.09492273731 98% => OK
Language errors: 0.0 4.19205298013 0% => OK
Sentences with positive sentiment : 3.0 4.33554083885 69% => OK
Sentences with negative sentiment : 6.0 4.45695364238 135% => OK
Sentences with neutral sentiment: 5.0 4.27373068433 117% => OK
What are sentences with positive/Negative/neutral sentiment?
Coherence and Cohesion:
Essay topic to essay body coherence: 0.190279975168 0.272083759551 70% => OK
Sentence topic coherence: 0.0724732142799 0.0996497079465 73% => OK
Sentence topic coherence SD: 0.0492931075209 0.0662205650399 74% => OK
Paragraph topic coherence: 0.122642222076 0.162205337803 76% => OK
Paragraph topic coherence SD: 0.0606588546893 0.0443174109184 137% => OK
Essay readability:
automated_readability_index: 10.5 13.3589403974 79% => Automated_readability_index is low.
flesch_reading_ease: 63.7 53.8541721854 118% => OK
smog_index: 3.1 5.55761589404 56% => Smog_index is low.
flesch_kincaid_grade: 8.4 11.0289183223 76% => OK
coleman_liau_index: 11.31 12.2367328918 92% => OK
dale_chall_readability_score: 7.78 8.42419426049 92% => OK
difficult_words: 50.0 63.6247240618 79% => More difficult words wanted.
linsear_write_formula: 8.0 10.7273730684 75% => OK
gunning_fog: 8.4 10.498013245 80% => OK
text_standard: 8.0 11.2008830022 71% => OK
What are above readability scores?
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Rates: 81.6666666667 out of 100
Scores by essay e-grader: 24.5 Out of 30
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Note: the e-grader does NOT examine the meaning of words and ideas. VIP users will receive further evaluations by advanced module of e-grader and human graders.