Abstract
Marine microbial biogeography has been studied intensively; however few studies address community variation across temporal and spatial scales simultaneously so far. Here we present a yearlong study investigating the dynamics of the free-living and particle-attached bacterioplankton community across a 100 km transect in the German Bight reaching from the Elbe estuary towards the open North Sea. Community composition was assessed using automated ribosomal intergenic spacer analysis and linked to environmental parameters applying multivariate statistical techniques. Results suggest that the spatial variation of the bacterioplankton community is defined by hydrographic current conditions, which separate the inner German Bight from the open North Sea and lead to pronounced differences in the coastal and offshore bacterioplankton community. However this spatial variation is overwhelmed by a strong temporal variation which is triggered by temperature as the main driving force throughout the whole transect. Variation in the free-living community was predominantly driven by temperature, whereas the particle-attached community exhibited stronger spatial variation patterns.
Highlights
Marine microbes are the most abundant organisms on earth [48], capable of thriving in all oceanic habitats and constitute an enormous biodiversity
Similar but reversed patterns were observed for dissolved organic carbon (DOC) which decreased on average from 341.3 μM in the estuary to 96.8 μM offshore, turbidity (41.5–1.1 FTU), colored dissolved organic matter (cDOM) (26.6–2.5) and Chlorophyll a (Chl a) (5.1 to 0.9 μg l−1)
Dissolved oxygen exhibited a similar but reversed pattern as temperature and lowest average values were measured in September (7.2 mg l−1); highest average values were measured in February (11.1 mg l−1)
Summary
Marine microbes are the most abundant organisms on earth [48], capable of thriving in all oceanic habitats and constitute an enormous biodiversity. Due to their inexhaustible metabolic and physiological versatility they are substantial key players in every biogeochemical cycle and are fundamental to ecosystem functioning. Lucas et al Helgol Mar Res (2016) 70:16 bacterial communities are complex and triggered by temporal and spatial components simultaneously. Only few studies consider both components and describe spatiotemporal variation patterns in oceanic environments [9, 17, 29]
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