Impacts of biogenic polyunsaturated aldehydes on metabolism and community composition of particle-attached bacteria in coastal hypoxia

Abstract. Eutrophication-driven coastal hypoxia has been of great interest for decades, though its mechanisms remain not fully understood. Here, we showed elevated concentrations particulate and dissolved polyunsaturated aldehydes (PUAs) associated with the hypoxic waters in bottom layer a salt-wedge estuary. Bacterial respiration within was mainly contributed by particle-attached bacteria (PAB) (> 0.8 µm), free-living (0.2–0.8 µm) only accounting 25 %–30 % total rate. The particle-adsorbed PUAs (? 10 µmol L?1) were directly quantified first time based on large-volume filtration subsequent on-site PUA derivation extraction. PUA-amended incubation experiments PAB sinking or suspended particles retrieved from low-oxygen also performed to explore impacts growth metabolism oxygen utilization. We found an increase cell response low-dose (1 but enhanced cell-specific bacterial production high-dose (100 L?1). Improved accompanied shift community structure increased dominance genus Alteromonas Gammaproteobacteria. thus conclude that high concentration aggregate may be crucial some species regulate structure. change could lead enhancement utilization during degradation organic matter likely contribute formation hypoxia. These findings are potentially important systems large river inputs, intense phytoplankton blooms driven eutrophication, strong developed below front.