Vocabulary

protozoan	простейшее животное
helminth	гельминт (паразитический червь)
outbreak	вспышка
epizootic	эпизоотия
handling	обращение, зд. уход, подход
sustained	длительный, непрерывный
infestation	инвазия (заражение паразитами)
to ingest	глотать, проглатывать
imminent	надвигающийся, неминуемый

12.5 Answer the questions

1.When do we use the terms “epidemic” and when “epizootic”?

2. What are the reasons for stresses and diseases?

3. How can the diseases be treated?

4. What are the preventive measures to avoid diseases and parasite problems?

13 Potential adverse effects

13.1 Read and translate the text with the help of a dictionary.

N ot too long ago, aquaculture was perceived as a cure for hunger and dwindling wild fish supplies. At the end of the twentieth century, given the rapid growth of the aquaculture industry, critics began questioning the real social and environmental impacts of aquaculture. The social impacts are generally felt more acutely in poorer countries. For example, people have been displaced from their homes and jobs by aquaculture operations, sometimes by operations that pollute land and water previously used by local residents.

A quaculture, like any farming activity, produces effects on the environment. Aquaculture uses energy and creates wastes. As aquaculture replaces wild habitat, changes to the ecosystem inevitably occur. Even where aquaculture operations are placed in non-pristine areas, potential exists for exotic (nonnative and genetically altered) aquaculture species to escape and adversely affect native species by competing for food and space, interbreeding and hybridizing native species, and spreading disease. Collecting wild larvae for rearing in aquaculture units can decimate native populations of fish, and can affect biodiversity. Toxic and bioaccumulative compounds can be harmful to people, including fish farmers themselves, and to plants and animals. Excessive discharge of organic wastes causes pollution.

The environmental impacts of effluents depend on the type of aquaculture practiced, and on farm management. Aquaculture can, in local situations, improve the environment or be environmentally benign. If ponds are properly managed, nutrient-rich discharges (soil and water) can be dredged for use in crop production, thereby reducing the need for soil amendments such as inorganic fertilizers.

F ish ponds can increase bird populations, which are pleasing to birdwatchers, but are disdained by fish farmers. While poorly managed fish ponds can serve as breeding grounds for vectors of animal and human disease, well-managed fish ponds can be used to control these vectors. Thus, fish farm management geared at minimizing negative environmental effects can be critical for balancing the farm's impact on the environment, and for its own long-term success.