The sea otter is a small mammal that lives in waters along the western coast of North America from California to Alaska. When some sea otter populations off the Alaskan coast started rapidly declining a few years ago, it caused much concern because sea otters play an important ecological role in the coastal ecosystem. Experts started investigating the cause of the decline and quickly realized that there were two possible explanations: environmental pollution or attacks by predators. Initially, the pollution hypothesis seemed the more likely of the two.
The first reason why pollution seemed the more likely cause was that there were known sources of it along the Alaskan coast, such as oil rigs and other sources of industrial chemical pollution. Water samples from the area revealed increased levels of chemicals that could decrease the otters' resistance to life-threatening infections and thus could indirectly cause their deaths.
Second, other sea mammals such as seals and sea lions along the Alaskan coast were also declining, indicating that whatever had endangered the otters was affecting other sea mammals as well. This fact again pointed to environmental pollution, since it usually affects the entire ecosystem rather than a single species. Only widely occurring predators, such as the orca (a large predatory whale), could have the same effect, but orcas prefer to hunt much larger prey, such as other whales.
Third, scientists believed that the pollution hypothesis could also explain the uneven pattern of otter decline: at some Alaskan locations the otter populations declined greatly, while at others they remained stable. Some experts explained these observations by suggesting that ocean currents or other environmental factors may have created uneven concentrations of pollutants along the coast.
The reading states that the population of one of the seawater animals, otter, has started to be declined due to 2 factors, environmental pollution or predators. Three reasons are mentioned in the reading to corroborate that the environmental pollution seems to be more possible. However, the professor in the lecture contends the reasons stated by author, while she explains ongoing research revealed the predator role is more highlighted.
First of all, the professor says that nobody could find the dead body of these animals. If water pollution had been the main reason of deteriorating the life of otters, why is not there any defunct of this species? On the contrary, the reading claims that increased level of chemical substances and oil in seawater is the pivot cause for this reducing.
Additionally, the professor continues to refute the second reason mentioned in the reading, which confirms that small sea mammals have also been declined and because these animals are small, they would not be the food of otters. The author adds that this fact proved that the whole of ecosystem is affected by one reason, thus nothing rather than pollution could be the reason. The professor ascertains that human haunting has had influence on the otter diets and although prior to this, they used to eat big animals, now their diet has changed to consume small animals.
Finally, according to the professor due to appearing few others in shallow water and rocky parts of the ocean, the third reason of the article emphasized that otters scattered in ocean irregularly shows pollution factor, would be rejected. Mentioning the size of the otter, they are large, the professor tells this point that the number of otters in the other parts of ocean which had been accessible to these animals easily are more than the other parts.
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while she explains ongoing research revealed the predator role is more highlighted.
while she explains ongoing researches revealed that the predator role is more highlighted.
flaws:
don't use '2 factors' but 'two factors'
Attribute Value Ideal
Score: 25 in 30
Category: Very Good Excellent
No. of Grammatical Errors: 1 2
No. of Spelling Errors: 0 2
No. of Sentences: 11 12
No. of Words: 303 250
No. of Characters: 1487 1200
No. of Different Words: 154 150
Fourth Root of Number of Words: 4.172 4.2
Average Word Length: 4.908 4.6
Word Length SD: 2.491 2.4
No. of Words greater than 5 chars: 102 80
No. of Words greater than 6 chars: 79 60
No. of Words greater than 7 chars: 52 40
No. of Words greater than 8 chars: 34 20
Use of Passive Voice (%): 0 0
Avg. Sentence Length: 27.545 21.0
Sentence Length SD: 7.644 7.5
Use of Discourse Markers (%): 0.636 0.12
Sentence-Text Coherence: 0.389 0.35
Sentence-Para Coherence: 0.635 0.50
Sentence-Sentence Coherence: 0.096 0.07
Number of Paragraphs: 4 4