Abstract：
Diatom-bacteria interactions and the associated bloom dynamics have not been fully understood in the coastal oceans. Here, we focus on the polyunsaturated aldehydes (PUAs) produced by diatoms in the post-bloom phase and look into their roles in microbial phosphorus (P) recycling outside of a P-limited estuary. The phytoplankton community in the bloom was dominated by PUAs-producing diatoms (Skeletonema costatum, Thalassiosira spp., and Pesudonitzschia delicates) with elevated concentrations of biogenic particulate PUAs. In addition, there were micromolar levels of particle-adsorbed PUAs hotspots with distinct compositions in and out of the bloom determined by a combining large-volume filtration and on-site derivation method. Field experiments were conducted to further assess the responses of particle-attached bacteria (PAB) to different PUAs amendments. We found no differences in the alkaline phosphatase (APase) activity and the abundance of PAB between inside and outside the bloom at a low PUAs dosage (<30 μM). However, for a high PUAs dosage (300 μM), APase activity and PAB growth were reduced significantly outside the bloom but no influences within the bloom. Our findings indicate that the hotspot-level oxylipins may play essential roles in bacterial P-remineralization in P-limited coastal areas. PAB can adapt to the high level of PUAs released by diatoms (or their resulting detritus) and potentially maintain a high rate of organic P recycling during the late stages of diatom blooms. Consequently, the interaction between oxylipin-rich diatoms and bacteria may affect phytoplankton blooms and carbon sequestration in the coastal oceans.
摘要：
在沿海海洋中，硅藻与细菌的相互作用以及相关的水华动力学尚未得到充分了解。这里,我们专注于在开花后阶段由硅藻产生的多不饱和醛（PUA），并研究它们在P限制河口外的微生物磷（P）回收中的作用。水华中的浮游植物群落以产生PUA的硅藻为主（Skeletonemacostatum，thalassiosiraspp.,和Pesudonitzschia的细粉）具有升高的生物颗粒PUA浓度。此外,通过结合大体积过滤和现场推导方法，确定了微摩尔水平的颗粒吸附PUA热点，在花华内外具有不同的组成。进行了田间试验，以进一步评估颗粒附着细菌（PAB）对不同PUA修正的反应。我们发现在低PUAs剂量（<30μM）下，水华内外的碱性磷酸酶（APase）活性和PAB丰度没有差异。然而,对于高PUA剂量（300μM），在开花外，APase活性和PAB生长显着降低，但在开花内没有影响。我们的发现表明，热点水平的氧化脂素可能在P受限沿海地区的细菌P再矿化中起重要作用。PAB可以适应硅藻（或其产生的碎屑）释放的高水平PUA，并可能在硅藻开花的后期保持较高的有机P回收率。因此,富含氧化脂素的硅藻与细菌之间的相互作用可能会影响沿海海洋中的浮游植物水华和碳固存。
