大亚湾网箱养殖区异养细菌和弧菌的数量动态

Variations of Vibrios and Heterotrophic Bacteria in the Caged-Culture Waters in Daya Bay

研究了大亚湾网箱养殖水体中细菌的数量动态,以探讨其变化规律与鱼病的关系。结果表明:总细菌、弧菌的数量变化各异,网箱内、网箱外和对照海区细菌数量分布与变化不同。养殖区异养细菌丰值期在4-5月份,5月份最高;网箱水体弧菌的丰值期在6-11月,最高在8月;网箱外丰值期在7-9月,最高在8月,对照海区最高值在9月,其他时间变化不大。无论是异养菌还是弧菌,细菌值大小顺序为网箱内、网箱外、对照海区。弧菌数量与部分环境因子相关性较为密切,但相关程度随不同空间而不同,可能受其他环境条件影响。弧菌的高值期与弧菌病的流行期相吻合,鱼体受伤或其他原因引起细菌感染也会使水体中细菌数量升高。

Bacterial variations in the caged-culture waters in Daya Bay were studied and their possible relationship with fish-disease outbreaks was investigated. Results showed that the total bacterial counts and the vibrio numbers changed differently in different regions： inside the cages, outside the cages and the compared region. Within the aquaculture region, heterotrophic bacteria density reached a high level from April to May and peaked in May. Inside the cage the vibrio density attained a high level during June and November period and peaked in August. Outside the cage the vibrio density was at high levels during July and September and peaked in August, whereas in the compared region, bacteria density peaked in September and changed little at other time. Regardless of vibrios or heterotrophic bacetria, the quantity of bacteria was the largest inside the cages, followed by outside the cages and then by compared region. The correlation between the density of vibrios and some environmental factors varied in different regions. The peak period of vibrio density matched the epidemic period of vibriosis in fish.