Photochemical transformation of terrestrial dissolved organic matter supports hetero- and autotrophic production in coastal waters

Marine Ecology Progress Series

Anssi V. V#xe4h#xe4talo¹  Laura Hoikkala¹  Risto Lignell¹  Hanna Aarnos¹ 

关键词: Dissolved organic nitrogen;    Apparent quantum yield;    Trophic transfer;    Photochemistry;    Bacterioplankton;    Phytoplankton;   

DOI  :  10.3354/meps09010

学科分类：海洋学与技术

来源: Inter-Research

【 摘 要 】

ABSTRACT: We assessed the responses of a nitrogen (N)-limited <10 µm plankton community from the Baltic Sea to the 12 d photochemical transformation of dissolved organic matter (DOM). The photochemical transformation of DOM increased the biomass and the production of heterotrophic bacteria, flagellates, and ciliates in the following 10 d bioassay. The succession of heterotrophic plankton indicated a 3-level trophic transfer of photoproduced bioavailable DOM through bacteria and flagellates to ciliates. The photochemical transformation of DOM also stimulated the biomass and the production of phytoplankton through the photoproduction of bioavailable N initially incorporated into bacterial biomass. The grazing of bacterioplankton supplied N to phytoplankton directly, presumably due to mixotrophy, and indirectly by releasing dissolved N. The carbon stable isotope signature of plankton biomass was similar to that of allochthonous carbon, indicating that the photochemical transformations concerned primarily terrestrial DOM and therefore represented a microbial link between terrestrial DOM and planktonic production. The bacterial production stimulated by the photochemically produced labile DOM was related to the number of photons absorbed during the photochemical transformation of DOM for the determination of apparent quantum yield. According to the apparent quantum yield, the calculated summertime photoproduction of labile substrates contributes 2 to 5% to total bacterial production in the northern Baltic Sea. According to this study, the photochemical transformation of terrestrial DOM influences not only the initial production of bacterioplankton but can also stimulate higher trophic levels and autotrophic plankton in coastal waters.

【 授权许可】

Unknown