[ti:Scientists Learn What Killed Caribbean Sea Urchins]
[by:www.21voa.com]
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[00:00.04]Scientists say a small parasite
[00:03.36]is the cause of death of many sea urchins
[00:06.80]in the Caribbean Sea.
[00:09.56]Sea urchins are simple animals
[00:12.44]that have long spines.
[00:15.28]Last year, the long-spined sea urchins,
[00:19.76]also known as Diadema antillarum,
[00:24.00]started getting sick.
[00:26.52]They were losing their spines
[00:29.28]and their sticky feet were losing their grip
[00:32.84]on the coral reefs.
[00:35.92]The loss of so many sea urchins,
[00:39.32]which eat algae that grow on the corals,
[00:43.24]affected the undersea environment
[00:47.20]from the Virgin Islands
[00:49.12]to Puerto Rico to Florida.
[00:53.04]Mya Breitbart led a team of scientists
[00:57.16]who investigated the sickness.
[00:59.88]She is a marine microbiologist
[01:03.32]at the University of South Florida.
[01:06.16]The team presented their study recently
[01:09.84]in the scientific publication
[01:12.28]Science Advances.
[01:15.32]"The case is closed," Breitbart said.
[01:18.80]The scientists compared the sick urchins
[01:22.64]to healthy ones
[01:24.44]and determined
[01:26.56]a single-celled parasite was to blame.
[01:31.88]Ian Hewson is a marine disease researcher
[01:35.48]at Cornell University
[01:37.44]in the state of New York.
[01:40.04]He said the team ruled out bacteria or viruses.
[01:44.08]But the team did see
[01:46.84]single-celled organisms called ciliates
[01:49.92]in the sick urchins.
[01:53.16]The scientists then
[01:55.04]put a group of healthy sea urchins
[01:57.24]grown in a laboratory
[01:59.48]in a tank with some of the parasites.
[02:03.60]Six of the 10 urchins in the tank later died.
[02:08.84]The scientists are now working
[02:11.04]to find a way to prevent future losses.
[02:15.00]They do not have a treatment for the sea urchins,
[02:18.08]but they are hoping to learn
[02:20.36]how the parasites spread
[02:22.48]so they can stop them.
[02:25.24]Breitbart noted another time
[02:28.12]that many sea urchins died in the 1980s.
[02:32.16]She did not know
[02:34.08]if the same parasites caused that problem.
[02:39.28]Don Levitan is a marine scientist
[02:42.48]at Florida State University
[02:44.88]who was not involved in the study.
[02:48.60]He said the two urchin die-offs,
[02:52.12]or widespread losses of the animals,
[02:56.04]have changed the coral reefs in the Caribbean Sea.
[03:00.84]He said at one time,
[03:03.24]they were covered with spiny urchins,
[03:06.04]but now they are covered in algae,
[03:08.92]sick from disease
[03:11.12]and stressed by rising water temperatures.
[03:16.08]"Coral reefs in the Caribbean
[03:17.88]are in trouble," he said.
[03:19.92]"We are at a different place than we were
[03:23.04]30, 40 years ago."
[03:25.88]I'm Dan Friedell. 更多听力请访问21VOA.COM