Monitoring of emaciation disease in cultured Paralichthys olivaceus of Jeju island during 2014–2015

Abstract

This study investigated the trend in emaciation infection outbreak in olive flounder (Paralichthys olivaceus) of Jeju island, South Korea, during 2014−2015. A total of 900 fish were systematically examined by PCR method using the EM-F/EM-R primer set in April, May, September, November, and December 2014, and the infection rate was recorded. In 2015, the same examination was conducted in March, May, July, and October but with 660 fish. It was found that the infection rate was 18.3~71.6% in 2014, which increased to 16.3~90.3% in 2015. Furthermore, September and December in 2014 and March, July, and October in 2015 showed a relatively higher infection rate. According to the infection trend analysis, which depended on the sample size, the infection occurred in all of fish sizes in this study and 11~30 cm fish group showed the highest infection rate. Histological examination confirmed that the kidney areas of the emaciating infected olive flounder contained several spores of 4~9 μm, and in severe cases, the elimination and destruction of tissue were confirmed by PCR. Thus, an important portion of farmed olive flounders in the Jeju region suffers from emaciation disease. This epidemiological survey serves as a useful reference on the emaciation disease of cultured olive flounders in Jeju.

Biodegradability of Plastics in the Open Environment

“…The former category includes agricultural plastics, such as mulch films that may be ploughed into the soil after use (Sander, 2019) and fishery plastic products with a high risk of loss to the open environment (Kim, Park, & Lee, 2014). Industrial composting differs from environmental conditions by providing stable and optimal conditions for biodegradation (see Chapter 4).…”