What is especially worrying about Pfiesteria blooms?
Giải bởi Vietjack
Điều gì đặc biệt đáng lo ngại về sự nảy nở của Pfiesteria?
A. Các điều kiện ngày càng trở nên thuận lợi cho sự lây lan của chúng
B. Chúng gây tử vong cho người tiếp xúc với chúng
C. Chúng phá hủy ngành công nghiệp đánh cá ở vùng nước ven biển của Mỹ
D. Các nhà nghiên cứu không biết chính xác nguyên nhân tạo ra của chúng
Dẫn chứng: Lately, however, blooms – or huge, dense populations – of Pfiesteria are appearing in coastal waters, and in such large concentrations the dinoflagellates become ruthless killers… More and more, conditions along the east coast seem to be favorable for Pfiesteria.
Tạm dịch: Tuy nhiên, gần đây, sự nở rộ - hoặc quần thể dày đặc, dày đặc - của Pfiesteria đang xuất hiện ở vùng nước ven biển, và ở nồng độ lớn như vậy, các loài tảo biển trở thành kẻ giết người tàn nhẫn. Hơn nữa, điều kiện dọc theo bờ biển phía đông dường như thuận lợi cho Pfiesteria.
Chọn đáp án là: A
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Pollution is a threat to many species on Earth, but sometimes it can cause species to thrive. Such is the case with Pfiesteria piscicida. A one-celled creature called a dinoflagellate, Pfiesteria inhabits warm coastal areas and river mouths, especially along the eastern United States. Although scientists have found evidence of Pfiesteria in 3,000-year-old sea floor sediments and dinoflagellates are thought to be one of the oldest life forms on earth, few people took notice of Pfiesteria.
Lately, however, blooms – or huge, dense populations – of Pfiesteria are appearing in coastal waters, and in such large concentrations the dinoflagellates become ruthless killers. The blooms emit powerful toxins that weaken and entrap fish that swim into the area. The toxins eventually cause the fish to develop large bleeding sores through which the tiny creatures attack, feasting on blood and flesh. Often the damage is astounding. During a 1991 fish kill, which was blamed on Pfiesteria on North Carolina’s Neuse River, nearly one billion fish died and bulldozers had to be brought in to clear the remains from the river. Of course, such events can have a devastating effect on commercially important fish, but that is just one way that Pfiesteria causes problems. The toxins it emits affect human skin in much the same way as they affect fish skin. Additionally, fisherman and others who have spent time near Pfiesteria blooms report that the toxins seem to get into the air, where once inhaled they affect the nervous system, causing severe headaches, blurred vision, nausea, breathing difficulty, short-term memory loss and even cognitive impairment.
For a while, it seemed that deadly Pfiesteria blooms were a threat only to North Carolina waters, but the problem seems to be spreading. More and more, conditions along the east coast seem to be favorable for Pfiesteria. Researchers suspect that pollutants such as animal waste from livestock operations, fertilizers washed from farmlands and waste water from mining operations have probably all combined to promote the growth of Pfiesteria in coastal waters.
What is true of Pfiesteria?
In which environment would you NOT expect a Pfiesteria bloom to develop?
Which of the following best characterizes the organization of the passage
