Seasonal patterns of bacterial communities in the coastal brackish sediments of the Gulf of Finland, Baltic Sea

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• 作者：Adrien Vetterli^a ; ^b ; ^{adrien.vetterli@helsinki.fi" class="auth_mail" title="E-mail the corresponding author} ; ^{adrien.vetterli@gmail.com" class="auth_mail" title="E-mail the corresponding author} ; Kirsi Hyyti&auml ; inen^a ; Minttu Ahjos^a ; ^c ; Petri Auvinen^d ; Lars Paulin^d ; Susanna Hietanen^a ; ^b ; Elina Leskinen^a ; ^b
• 关键词：Nucleic acids ; Bacteria ; Sediment ; Microbes ; Population structure ; Population dynamics ; Pyrosequencing ; 16S rDNA
• 刊名：Estuarine, Coastal and Shelf Science
• 出版年：2015
• 出版时间：5 November 2015
• 年：2015
• 卷：165
• 期：Complete
• 页码：86-96
• 全文大小：2593 K

文摘

Coastal areas are critical in mitigating the impact of nutrient runoffs and downstream eutrophication of aquatic ecosystems. In the Gulf of Finland, the easternmost sub-basin of the Baltic Sea, seasonal and long-term oxygen depletion at the surface of the sediment feeds back the eutrophication loop by promoting the release of nutrients locked in the sediment matrix. In order to understand how the bacterial community responds to the seasonal variations, we sequenced ribosomal gene fragments from the top sediment layer at two coastal sites in southern Finland in spring, summer and late autumn during two consecutive years. Analysis of the samples collected at a shallow (11 m) and deep site (33 m) revealed that the overall community composition was rather constant over time with an extensive collection of shared operational taxonomic units (OTU) between sites. The dominant taxa were related to organoheterotrophs and sulfate reducers and the variation in community structure was linked to the availability of organic matter in the surface sediment. Proteobacteria formed the most abundant and diverse group. The taxa characteristic of spring samples belonged primarily to Actinobacteria, possibly of fresh water origin and linked to humic carbon. Summer communities were characterized by an increase in the number of reads associated with heterotrophic bacteria such as Bacteroidetes which feed on labile organic matter from spring bloom. Taxa typical of autumn samples were linked to Cyanobacteria and other bloom-forming bacteria from the overlying water and to bacteria feeding on organic matter drifting from the phytal zone.