Summary The use of antibiotics in aquaculture may cause development of antibiotic resistance among pathogens infecting cultured animals and humans. However, this is a recent issue and has not yet been thoroughly investigated. Furthermore, there is limited knowledge about the environmental effects of antibiotic use in aquaculture. It is well known that antibiotics are commonly used in shrimp farming to prevent or treat disease outbreaks, but there is little published documentation on details of usage patterns. This study, conducted in 2000, shows that a large proportion of shrimp farmers along the Thai coast used antibiotics in their farms. Of the seventy‐six farmers interviewed, 74% used antibiotics in shrimp pond management. Most farmers used them prophylactically, some on a daily basis, and at least thirteen different antibiotics were used. Many farmers were not well informed about efficient and safe application practices. A more restrictive use of antibiotics could have positive effects for the individual farmer and, simultaneously, decrease impacts on regional human medicine and adjacent coastal ecosystems. It is likely that dissemination of information could contribute to a decreased use of antibiotics, without decreasing the level of shrimp production.

In Southeast Asia the aquatic macrophyte water spinach (Ipomoea aquatica Forsk.) is a popular vegetable that is cultivated in freshwater courses. These often serve as recipients for domestic and other sorts of wastewater that often contain a variety of pollutants, such as heavy metals. In addition, fertilizers are frequently used where water spinach is cultivated commercially for the food market. To estimate the importance of ambient nutrient concentrations for accumulation of mercury (Hg), cadmium (Cd), and lead (Pb) in water spinach, plants were exposed to nutrient solutions of different strength and with varying metal concentrations. Metal-induced toxic effects, which might possibly affect the yield of the plants, were also studied. The lower the nutrient strength in the medium was, the higher the metal concentrations that accumulated in the different plant parts and the lower the metal concentration in the medium at which metal-induced toxic effects occurred. Accordingly, internal metal concentrations in the plants were correlated to toxic effects. Plants exposed to metals retained a major proportion of the metals in the roots, which had a higher tolerance than shoots for high internal metal concentrations.

No abstract

No abstract

No abstract