Sea otters are a small mammal that lives in the waters along North America's west coast from California to Alaska. A few years ago some of the sea otter populations off of the Alaskan coast started to decline rapidly and raised several concerns because of their important role in the coastal ecosystem. Experts began investigating and came up with two possible explanations. One explanation was environmental pollution and the second was attacks by predators.
At first it seemed as if the pollution was the most likely cause for the population decline. One reason pollution was more likely was because of the known pollution sources along the Alaskan coast such as oil rigs. Also water samples taken in the area showed increased levels of chemicals that could decrease the otters' immune systems and indirectly result in their deaths.
Another thing that pointed to pollution as the culprit was the decline of other sea mammals such as seals in the same areas. This indicated that whatever was affecting the otters was also affecting the other sea mammals. Environmental pollution usually affects an entire ecosystem instead of just one species. Only predators that occurred in a large area, such as orcas (a large predatory whale), could cause the same effect, but they usually hunt larger prey.
Finally, scientists believed the pollution hypothesis would also explain the uneven pattern of otter decline. In some Alaskan locations the otter population declined greatly while other populations remained stable. Some experts suggested this could be explained by ocean currents, or other environmental factor, might have created uneven concentrations of pollutants along the coast.
The lecture holds an opposite point of view to that of the reading passage on the topic of why the sea otter population declined off the Alaskan coast. According to the reading passage, the rapid decline in the sea otter was because of the polluted water in the area. However, the lecture points out that it's most likely due to predators.
First, the reading passage states that pollutants are the reason behind the decline especially that there are many sources of pollutants in the area like oil rigs and other industrial and chemical pollutants. On the other hand, the lecture illustrates that although analysis revealed increased levels of chemicals in the area, this should not prove the pollution theory because if sea otters were killed by infections, their bodies would have washed up to the shore. Given that no washed-up sea otter bodies were found, we can conclude that it must be predators not something else.
Second, the reading passage claims that if we consider that other sea mammals are declining too, we can say with confidence that it's pollution because it's the only thing that could have an effect on the entire ecosystem, given that Orca whales, which could have a similar effect by predators, usually hunt larger prey like whales not small mammals like sea otter. The lecture refutes these claims mentioning that due to the fact that whales started to disappear in the area because of human hunters leading orcas to search for alternative diet in small mammals like sea otter, sea lion and others and this led to the decline of all these sea mammals.
Lastly, the lecture challenges the reading passage in explaining why sea otter population is declining faster in some areas while the population is relatively stable in other areas. The reading passage argues that that happened because of uneven distribution of pollutants which are at high levels in some areas and at lower levels in other areas. In contrast, the professor in the lecture believes that it is because the nature of the location and how accessible it is to Orcas. The locations which are easily accessible to the orcas will not be safe for sea otters because they are going to be easy prey for the Orcas. However, shallow and rocky locations which are not accessible to Orcas will have larger number of population of sea otter.
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Grammar and spelling errors:
Line 5, column 152, Rule ID: IT_IS[17]
Message: Did you mean 'it's' (='it is') instead of 'its' (possessive pronoun)?
Suggestion: it's; it is
...h confidence that its pollution because its the only thing that could have an effec...
^^^
Transition Words or Phrases used:
but, first, however, if, lastly, second, so, while, as to, in contrast, on the other hand
Attributes: Values AverageValues Percentages(Values/AverageValues)% => Comments
Performance on Part of Speech:
To be verbs : 17.0 10.4613686534 163% => OK
Auxiliary verbs: 9.0 5.04856512141 178% => OK
Conjunction : 7.0 7.30242825607 96% => OK
Relative clauses : 21.0 12.0772626932 174% => OK
Pronoun: 32.0 22.412803532 143% => Less pronouns wanted
Preposition: 56.0 30.3222958057 185% => OK
Nominalization: 9.0 5.01324503311 180% => OK
Performance on vocabulary words:
No of characters: 1934.0 1373.03311258 141% => OK
No of words: 396.0 270.72406181 146% => Less content wanted.
Chars per words: 4.88383838384 5.08290768461 96% => OK
Fourth root words length: 4.46091344257 4.04702891845 110% => OK
Word Length SD: 2.40102518661 2.5805825403 93% => OK
Unique words: 184.0 145.348785872 127% => OK
Unique words percentage: 0.464646464646 0.540411800872 86% => More unique words wanted or less content wanted.
syllable_count: 619.2 419.366225166 148% => OK
avg_syllables_per_word: 1.6 1.55342163355 103% => OK
A sentence (or a clause, phrase) starts by:
Pronoun: 4.0 3.25607064018 123% => OK
Article: 11.0 8.23620309051 134% => OK
Subordination: 0.0 1.25165562914 0% => More adverbial clause wanted.
Conjunction: 0.0 1.51434878587 0% => OK
Preposition: 3.0 2.5761589404 116% => OK
Performance on sentences:
How many sentences: 13.0 13.0662251656 99% => OK
Sentence length: 30.0 21.2450331126 141% => The Avg. Sentence Length is relatively long.
Sentence length SD: 78.664669182 49.2860985944 160% => OK
Chars per sentence: 148.769230769 110.228320801 135% => OK
Words per sentence: 30.4615384615 21.698381199 140% => OK
Discourse Markers: 6.84615384615 7.06452816374 97% => OK
Paragraphs: 4.0 4.09492273731 98% => OK
Language errors: 1.0 4.19205298013 24% => OK
Sentences with positive sentiment : 6.0 4.33554083885 138% => OK
Sentences with negative sentiment : 4.0 4.45695364238 90% => OK
Sentences with neutral sentiment: 3.0 4.27373068433 70% => OK
What are sentences with positive/Negative/neutral sentiment?
Coherence and Cohesion:
Essay topic to essay body coherence: 0.236278151206 0.272083759551 87% => OK
Sentence topic coherence: 0.0998749260836 0.0996497079465 100% => OK
Sentence topic coherence SD: 0.0784609486872 0.0662205650399 118% => OK
Paragraph topic coherence: 0.162571649177 0.162205337803 100% => OK
Paragraph topic coherence SD: 0.059992867964 0.0443174109184 135% => OK
Essay readability:
automated_readability_index: 16.8 13.3589403974 126% => OK
flesch_reading_ease: 41.03 53.8541721854 76% => OK
smog_index: 8.8 5.55761589404 158% => OK
flesch_kincaid_grade: 15.0 11.0289183223 136% => OK
coleman_liau_index: 11.62 12.2367328918 95% => OK
dale_chall_readability_score: 8.79 8.42419426049 104% => OK
difficult_words: 92.0 63.6247240618 145% => OK
linsear_write_formula: 10.5 10.7273730684 98% => OK
gunning_fog: 14.0 10.498013245 133% => OK
text_standard: 9.0 11.2008830022 80% => OK
What are above readability scores?
---------------------
Write the essay in 20 minutes.
Rates: 73.3333333333 out of 100
Scores by essay e-grader: 22.0 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.