Sorbonne Universités, UPMC Univ Paris 06, UMR 7621, Laboratoire d'Océanographie Microbienne, Observatoire Océanologique, 66650, Banyuls/mer, France.
Environ Sci Pollut Res Int. 2015 Sep;22(18):13638-53. doi: 10.1007/s11356-014-3848-x. Epub 2014 Nov 20.
Spatial increases and temporal shifts in outbreaks of gelatinous plankton have been observed over the past several decades in many estuarine and coastal ecosystems. The effects of these blooms on marine ecosystem functioning and particularly on the dynamics of the heterotrophic bacteria are still unclear. The response of the bacterial community from a Mediterranean coastal lagoon to the addition of dissolved organic matter (DOM) from the jellyfish Aurelia aurita, corresponding to an enrichment of dissolved organic carbon (DOC) by 1.4, was assessed for 22 days in microcosms (8 l). The high bioavailability of this material led to (i) a rapid mineralization of the DOC and dissolved organic nitrogen from the jellyfish and (ii) the accumulation of high concentrations of ammonium and orthophosphate in the water column. DOM from jellyfish greatly stimulated heterotrophic prokaryotic production and respiration rates during the first 2 days; then, these activities showed a continuous decay until reaching those measured in the control microcosms (lagoon water only) at the end of the experiment. Bacterial growth efficiency remained below 20%, indicating that most of the DOM was respired and a minor part was channeled to biomass production. Changes in bacterial diversity were assessed by tag pyrosequencing of partial bacterial 16S rRNA genes, DNA fingerprints, and a cultivation approach. While bacterial diversity in control microcosms showed little changes during the experiment, the addition of DOM from the jellyfish induced a rapid growth of Pseudoalteromonas and Vibrio species that were isolated. After 9 days, the bacterial community was dominated by Bacteroidetes, which appeared more adapted to metabolize high-molecular-weight DOM. At the end of the experiment, the bacterial community shifted toward a higher proportion of Alphaproteobacteria. Resilience of the bacterial community after the addition of DOM from the jellyfish was higher for metabolic functions than diversity, suggesting that jellyfish blooms can induce durable changes in the bacterial community structure in coastal lagoons.
在过去几十年中，许多河口和沿海生态系统都观察到凝胶状浮游生物爆发的空间增加和时间推移。这些水华对海洋生态系统功能的影响，特别是对异养细菌动态的影响尚不清楚。在微宇宙（8 升）中，评估了来自地中海沿海泻湖的细菌群落对水母 Aurelia aurita 溶解有机物（DOM）的添加的响应，该响应对应于溶解有机碳（DOC）的富集约 1.4。在 22 天内进行了评估。这种材料具有很高的生物利用度，导致（i）水母的 DOC 和溶解有机氮迅速矿化，以及（ii）水柱中铵和正磷酸盐浓度的积累。水母的 DOM 在最初的 2 天内极大地刺激了异养原核生物的生产力和呼吸速率；然后，这些活动持续衰减，直到实验结束时达到对照微宇宙（仅泻湖水）中测量的值。细菌生长效率仍低于 20％，表明大部分 DOM 被呼吸，一小部分被引导到生物量生产中。通过部分细菌 16S rRNA 基因、DNA 指纹图谱和培养方法的标签焦磷酸测序评估了细菌多样性的变化。虽然对照微宇宙中的细菌多样性在实验过程中变化不大，但水母 DOM 的添加会诱导迅速生长的假交替单胞菌和弧菌属。9 天后，细菌群落主要由更适应代谢高分子 DOM 的拟杆菌门组成。在实验结束时，细菌群落向更高比例的α变形菌门转移。与多样性相比，水母 DOM 添加后细菌群落的代谢功能的恢复能力更高，这表明水母水华可能会导致沿海泻湖的细菌群落结构发生持久变化。
