Английский язык: Сборник текстов и упражнений для студентов специальностей "Промышленное рыболовство". Дьякова Н.П. - 65 стр.

ease are observable. Disease and parasite organisms are almost always present in the
culture environment, but at very low levels. They only produce disease signs when
they are promoted by a lack of resistance in the aquaculture species. An analogy can
be drawn in humans. Students in a classroom may be exposed to people with the flu,
but not everyone is infected. The immune status of the various individuals plays an
important role in who will ultimately show flue symptoms. Students who are stressed
(for example, by getting too little sleep) are often much more susceptible than those
who are not.
The number of chemicals that can be used to treat disease and parasite problems in
aquatic animals is small. Only about 10 compounds have been approved for species
that are being reared for direct human consumption. Among them, few are effective
at controlling bacteria, some work on a few parasites but not others, and many are
themselves toxic if given in improper doses. Some treatment chemicals are effective
when added to the water, but some must be ingested by the aquaculture organisms.
Animals that are experiencing disease or parasite problems often refuse to eat, mak-
ing treatment difficult.
Good overall management of the culture system is perhaps the best way to avoid dis-
ease and parasite problems. However, even the best managers experience epizootics
on occasion. Treatment chemicals of various kinds should be available, and the cul-
turist should know how to use those chemicals. Chemicals such as antibiotics should
not be used routinely, but should only be employed when there is a problem requring
treatment, or when there is a very strong probability that a disease or parasite epizoo-
tic is imminent.

                                      Vocabulary

      susceptible                              восприимчивый, чувствительный
      array of                                 масса, множество
      protozoan                                простейшее животное
      helminth                                 гельминт (паразитический червь)
      copepods                                 веслоногие ракообразные
      outbreak                                 вспышка
      epizootic                                эпизоотия
      to stress                                подвергать стрессу
      to deteriorate                           ухудшаться
      to undergo                               переносить, подвергаться
      handling                                 обращение, зд. уход, подход
      sustained                                длительный, непрерывный
      onset                                    наступление
      infestation                              инвазия (заражение паразитами)
      ultimately                               в конце концов
      to ingest                                глотать, проглатывать
      to avoid                                 избегать

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