ENVIRONMENTAL IMPACT OF FISH CULTURE ON IN SITU SEDIMENTARY MICROBIAL COMMUNITIES AND THEIR RESPONSES - SIGNATURE LIPID BIOMARKER ANALYSIS

最近，沿海地区养鱼对环境的影响引起了相当大的关注。从养鱼场向环境中大量输入未消耗的饲料和粪便物质，导致沉积物中有机物富集，导致微生物过程的需氧量增加，最终导致高度还原或缺氧条件。虽然微生物群落是分解过程中的主要参与者，但由于缺乏合适的方法，尚未对有机富集区微生物群落的变化进行研究，这将表明环境健康状况。利用生物标志物（SLB）分析技术研究了鱼类养殖区及其周边环境中微生物生物量及其群落结构的季节性和区域性变化，并与沉积物特征进行了沿着。 ...更多信息 分别采自广岛县田岛和横岛的养殖场，并分四季采集表层沉积物样品。沉积物样品进行了分析的温度，pH值，氧化还原电位（Eh），酸挥发性硫化物硫（AVS-S），燃烧失重（IL），脂质磷酸盐，磷脂酯连接的脂肪酸（PLFA）。在实验室条件下，通过培养试验研究了饲料对微生物生物量的影响。鱼类养殖区沉积物具有低Eh、高IL和AVS-S的特征，表明沉积物处于高度还原或缺氧状态。环境区沉积物的特征与鱼类养殖区完全不同。沉积物参数的季节性变化不太明显，除了温度。作为微生物生物量指标的脂质磷酸盐表现出明显的区域差异。从鱼类养殖区的沉积物中含有显着较高浓度的脂质磷酸盐比周围的沉积物，表明高有机质的影响，从养鱼场输入。培养实验结果表明，添加饲料的沉积物中的脂质磷酸盐的水平始终高于对照组，支持饲料对有机质和脂质磷酸盐水平的影响。PLFA组的区域差异显着，高水平的鱼类养殖区和周围地区的低值。8种微生物生物标志物PUFA（微真核生物）、16：1、17：1和18：1（细菌）、10 Me 16：0（SRB ;脱硫菌属）、br 17：1（脱硫弧菌属），用15：0和17：0的iso和anteiso（厌氧菌）描述微生物群落结构。除10 Me 16：0和br 17：1外，养殖区微生物生物标志物含量均显著高于周边区，根据脂质磷酸盐的年平均值，将研究区划分为I级（<=30 nmol/g）：IL、AVS和微生物生物标志物低值，Eh（氧化）高值; IV级（>=100 nmol/g）：IL、AVS和微生物生物标志物的高值和Eh的低值（高度缺氧）;和二级（31-70 nmol/g）和III级（71-99 nmol/g）：沉积物参数和微生物生物标志物在这些地区之间存在显著差异，除Ⅱ级和Ⅲ级之间的差异外，表明沉积物微生物群落结构存在差异。在IL（8-10%）和Eh（-200至-100 mV）的窄范围内的微生物生物标志物的变化显著大于在IL（3-8%）和Eh（>-100 mV）的范围内观察到的变化。养鱼对周围地区的影响不明显。这些结果表明，从沉积物参数检测不到的变化可以很容易地检测到生物标志物分析。此外，100 nmol/g脂质磷酸盐的水平可被视为临界水平，定期监测脂质磷酸盐将提供有关环境健康状况的信息。少

Recently, considerable attention has been focused on the environmental impact of fish culture in coastal areas. A large input of unconsumed feeds and fecal matter from fish farms into the environment results in an organic enrichment in sediments leading to an increased oxygen demand for microbial processes and ultimately highly reduced or anoxic conditions. Although microbial communities are principal playrs in decomposition processes, changes in microbial communities in areas of organic enrichment, which will indicate the environmental health, have not however been examined due to the paucity of suitable methods. Signature lipid biomarker (SLB) analysis, which is reported to be one of the more sensitive chemical methods, was used to examine the seasonal and regional variation in microbial biomass and its community structure along with sediment characteristics in fish culture areas and their ambient environment.Eight and three stations from fish culture and ambient areas were selected, … More respectively from culture farms in Tashima and Yokoshima of Hiroshima Prefecture and surface sediment samples were collected during four seasons. Sediment samples were analyzed for temperature, pH,oxidation-reduction potential (Eh), acid volatile sulfide-sulfur (AVS-S), weight loss on ignition (IL), lipid phosphate, and phospholipid ester-linked fatty acids (PLFA). In laboratory, incubation experiments were conducted to evaluate the influence of feed on microbial biomass. Sediments from fish.culture areas were characterized by low Eh, and high IL and AVS-S,indicating that the sediments were either under highly reduced or anoxic condition. The characteristics of sediments from ambient areas were totally different from fish culture areas. Seasonal was less pronounced than regional variation of sediment parameters, except temperature. Lipid phosphate, an indicator of microbial biomass, showed a marked regional variation. Sediments from fish culture areas contained significantly higher concentrations of lipid phosphate than the ambient sediments, indicating the influence of high organic matter input from fish farms. Results of incubation experiments revealed that the levels of lipid phoshphate in sediments added with feed were always high in comparison with the control, supporting the influence of feed on the levels of organic matter and lipid phosphate. Marked regional variation of PLFA groups was observed with high levels in fish culture areas and low values in ambient areas. The proportions of eight microbial biomarkers PUFA (microeukaryotes), 16 : 1,17 : 1 and 18 : 1 (bacteria), 10Me 16 : 0 (SRB ; Desulfobacter sp.), br17 : 1 (Desulfovibrio sp.), iso and anteiso of 15 : 0 and 17 : 0 (anaerobes) were used to describe the microbial community structure. The microbial biomarkers, except 10Me 16 : 0 and br17 : 1, in fish culture areas were significantly higher than that in ambient areas.Based on the annual mean values of lipid phosphate, the study area was divided into Level I (<=30 nmol/g) : low values of IL,AVS and microbial biomarkers, and high values of Eh (oxic) ; Level IV (>=100 nmol/g) : high values of IL,AVS and microbial biomarkers and low values of Eh (highly anoxic) ; and Level II (31-70 nmol/g) and Level III (71-99 nmol/g) : levels of those parameters were found between Levels I and IV.Sediment parameters and microbial biomarkers differed significantly among these areas, except between Level II and III,indicating the differences in microbial community structure of sediments. The variations of microbial biomarkers at a narrow range of IL (8-10%) and Eh (-200 to -100 mV) were significantly greater than that observed in a range of IL (3-8%) and Eh (>-100 mV). Effect of fish culture on ambient areas was not evident. These results suggest that changes which are not detectable from sediment parameters can be easily detected by biomarker analysis. Furthermore, the level of 100 nmol/g lipid phosphate can be considered as a critical level and a regular monitoring of lipid phosphate will provide information about the status of environmental health. Less