Bacterial DMSP metabolism during the senescence of the spring diatom bloom in the Northwest Atlantic

Marine Ecology Progress Series

Maurice Levasseur¹  Sonia Michaud¹  Ronald P. Kiene¹  Michael Scarratt¹  Richard B. Rivkin¹  Anissa Merzouk¹  Martine Lizotte¹ 

关键词: DMSP cycling;    Bacterial metabolism;    Bloom senescence;    Northwest Atlantic Ocean;   

DOI  :  10.3354/meps07664

学科分类：海洋学与技术

来源: Inter-Research

【 摘 要 】

ABSTRACT: The impact of the decline of the vernal bloom on the bacterial metabolism of dimethylsulfoniopropionate (DMSP), the precursor of dimethylsulfide (DMS), was investigated during a 7 d Lagrangian study conducted in the Northwest Atlantic in spring 2003. Daily variations in bacterial leucine incorporation, dissolved DMSP (DMSP_d) uptake and DMS production rates were measured in the surface mixed layer (SML) and in the deep chlorophyll a maximum (DCM) that formed as the bloom collapsed. Seawater samples were amended with ³⁵S-DMSP_d, and the products of bacterial DMSP_d degradation were measured during 3 h on-board incubations. The gradual decrease in phytoplankton biomass and diatom abundance measured in the SML was accompanied by a sharp doubling of the bacterial abundance and a peak in leucine incorporation rate on Day 2, suggesting that bacteria responded to a transient pulse in dissolved organic matter. Bacterial DMSP_d uptake and DMS production were highest on Days 1 and 2 (1.2 and 0.10 nmol l^-1 h^-1, respectively), but rapidly decreased by Day 3, suggesting that DMSP_d was becoming a less important substrate for the growing bacterial assemblage as other substrates became available. Bacterial DMSP_d uptake and DMS production rates were also low in the DCM despite very high DMS yields (40 to 50%), showing that neither the decline of the diatom spring bloom in the SML nor the accumulation of cells in the DCM resulted in a stimulation of bacterial DMSP metabolism or accumulation of DMS. The present study provides new field evidence for the potential uncoupling between bacterial production and DMS dynamics likely due to variations in the availability of other S-containing organic compounds released during the decay of phytoplankton blooms.

【 授权许可】

Unknown