Over the past five years, an epidemic disease broke out in Pelteobagrus fulvidraco ponds of Zhejiang Province. The diseased fish mainly exhibits head splitting and surface bleeding; dissection results reveal hepatonep...Over the past five years, an epidemic disease broke out in Pelteobagrus fulvidraco ponds of Zhejiang Province. The diseased fish mainly exhibits head splitting and surface bleeding; dissection results reveal hepatonephromegaly and abdominal bleeding. A bacterial strain HSY201301 was isolated from the liver tissue of P. fulvidraco with typical symptoms. Artificial infection experiment confirmed that the isolated strain had a strong virulence to healthy P. fidvidraco, leading to similar symptoms to naturally infected P. fulvidraco. The isolated strain was identified as an Edwardsiella tarda strain according to conventional morphological, physiological, biochemical characteristics and 16S rRNA gene sequence. Results of drug susceptibility test indicated that the isolated strain was sensitive to cipro- floxacin, doxitard, penicillin, doxycycline, and rocephin. This study laid solid foundation for effective prevention and control of E. tarda.展开更多
[Objectives] This study was conducted to strengthen the understanding of the variation laws of pH in fishery waters. [Methods]Based on the investigation data of pH, dissolved oxygen(Do), water temperature(T) and chlor...[Objectives] This study was conducted to strengthen the understanding of the variation laws of pH in fishery waters. [Methods]Based on the investigation data of pH, dissolved oxygen(Do), water temperature(T) and chlorophyll a(Chl. a) of the fishery waters in Quzhou City from 2017 to 2020, the seasonal variation characteristics and influencing factors of pH in the fishery waters were analyzed and discussed. [Results] The pH of the fishery waters in Quzhou City was in the range of 6.40-11.3, and was characterized by the highest seasonal variation in spring and the lowest in winter. The correlation analysis showed that water temperature and pH were significantly positively correlated in spring and summer(P<0.05), and the photosynthesis of phytoplankton was the main reason that affected the pH of water bodies in spring and summer. There was a negative correlation between water temperature and pH in winter, and the pH in the natural waters had a significant negative correlation with water temperature(P<0.05). The balance of carbonate system in the water bodies was the main reason that affected the pH of water in winter. The level of water eutrophication(Chl. a) affected the pH of fishery waters to a certain extent. When Chl. a<10 μg/L, there was a significant positive correlation between the pH of fishery waters and Chl. a(P<0.05). Various environmental factors had different effects on the pH of different types of fishery waters. The stepwise regression analysis showed that the pH of natural waters was mainly affected by Chl. a, and the pH of aquaculture waters was mainly affected by water temperature and dissolved oxygen. [Conclusions]This study provides certain theoretical support for actual production management.展开更多
文摘Over the past five years, an epidemic disease broke out in Pelteobagrus fulvidraco ponds of Zhejiang Province. The diseased fish mainly exhibits head splitting and surface bleeding; dissection results reveal hepatonephromegaly and abdominal bleeding. A bacterial strain HSY201301 was isolated from the liver tissue of P. fulvidraco with typical symptoms. Artificial infection experiment confirmed that the isolated strain had a strong virulence to healthy P. fidvidraco, leading to similar symptoms to naturally infected P. fulvidraco. The isolated strain was identified as an Edwardsiella tarda strain according to conventional morphological, physiological, biochemical characteristics and 16S rRNA gene sequence. Results of drug susceptibility test indicated that the isolated strain was sensitive to cipro- floxacin, doxitard, penicillin, doxycycline, and rocephin. This study laid solid foundation for effective prevention and control of E. tarda.
基金Supported by Huzhou Public Welfare Application Research Project(2017GY)National Staple Freshwater Fish Industrial Technology System(CARS-45-39)。
文摘[Objectives] This study was conducted to strengthen the understanding of the variation laws of pH in fishery waters. [Methods]Based on the investigation data of pH, dissolved oxygen(Do), water temperature(T) and chlorophyll a(Chl. a) of the fishery waters in Quzhou City from 2017 to 2020, the seasonal variation characteristics and influencing factors of pH in the fishery waters were analyzed and discussed. [Results] The pH of the fishery waters in Quzhou City was in the range of 6.40-11.3, and was characterized by the highest seasonal variation in spring and the lowest in winter. The correlation analysis showed that water temperature and pH were significantly positively correlated in spring and summer(P<0.05), and the photosynthesis of phytoplankton was the main reason that affected the pH of water bodies in spring and summer. There was a negative correlation between water temperature and pH in winter, and the pH in the natural waters had a significant negative correlation with water temperature(P<0.05). The balance of carbonate system in the water bodies was the main reason that affected the pH of water in winter. The level of water eutrophication(Chl. a) affected the pH of fishery waters to a certain extent. When Chl. a<10 μg/L, there was a significant positive correlation between the pH of fishery waters and Chl. a(P<0.05). Various environmental factors had different effects on the pH of different types of fishery waters. The stepwise regression analysis showed that the pH of natural waters was mainly affected by Chl. a, and the pH of aquaculture waters was mainly affected by water temperature and dissolved oxygen. [Conclusions]This study provides certain theoretical support for actual production management.
