象山港大黄鱼(Pseudosciaena crocea)网箱养殖区及邻近海域沉积物中异养细菌生态分布

BACTERIAL ECOLOGICAL DISTRIBUTION IN SEDIMENT OF A YELLOW CROAKER PSEUDOSCIAENA CROCEA CAGE FARM AND ADJACENT SITES IN XIANGSHAN BAY

调查了投饵期(8月)和越冬期(11月)象山港大黄鱼(Pseudosciaena crocea)网箱养殖区及周围海域沉积物中有机物含量、异养细菌数量和群落结构。结果表明:养殖区沉积物(0—5cm层)中总磷、总有机氮含量在投饵期和越冬期均显著高于邻近对照海域(P<0.05)。沉积物中异养细菌、弧菌数量分别在3.2×104—5.2×105 CFU/g和2.2×103—1.7×105 CFU/g之间,养殖区沉积物细菌数量大于周围邻近海域。16S r DNA法分析结果表明,研究区域投饵期的优势属均为弧菌属,越冬期为芽孢杆菌属。各采样区异养细菌的多样性表现为养殖区<周围邻近区域、投饵期<越冬期。异养细菌数与沉积物中TON、TP含量呈显著正相关,表明象山港大黄鱼养殖区沉积物中可培养异养细菌数可能受有机氮和磷酸盐含量的限制。研究表明,大黄鱼网箱养殖对象山港沉积物中的有机积累、异养细菌群落结构组成及多样性影响显著。

We investigated the organic matter contents, bacterial abundance, and diversity in the sediments below yellow croaker Pseudosciaena crocea farming cage and adjacent reference sites in Xiangshan Bay during feeding period(Aug.) and wintering period(Nov.). The total phosphorus and total nitrogen contents of the cage site were significant higher than those at adjacent reference sites in both periods(P<0.05). The numbers of heterotrophic bacteria and Vibrio ranged from 3.2×104—5.2×105 CFU/g and from 2.2×103—1.7×105 CFU/g, respectively. Total number of bacteria at cage site was higher than that of the control sites. Analysis on 16 S r DNA showed that the microbial communities at both farm site and reference sites were dominated by Vibrio in the feeding period and by Bacilli in the wintering period. The benthic bacteria in the farm site showed a higher level of microbial diversity than the reference sites, and higher diversity occurred in the November. The number of heterotrophic bacteria were highly correlated to TON and TP contents, indicating that the development of culturable heterotrophic bacteria might be limited by total organic nitrogen and phosphorous concentration. Therefore, cage-culture activities affected significantly the organic enrichment, and bacterial community structure and diversity in the sediments of Xiangshan Bay.