Abstract
Particulate organic carbon (POC) flux is hypothesized to be the most important parameter influencing activity and biomass of prokaryotic and faunal communities in the abyssal seafloor, but there is little evidence of POC-related changes in community composition of prokaryotes. This hypothesis was tested by 16S rRNA-gene-based analysis of prokaryotic DNA and RNA extracted from abyssal seafloor sediments during periods of low and high POC flux. Fingerprint analysis of prokaryotic communities indicated that approximately 50% of the phylotypes were identical at each sediment horizon, regardless of the temporal variations in POC flux. However, phylotypes were also detected that represented a relatively dynamic component of these communities and were probably strongly influenced by the prevalent POC flux regime. These patterns were also detected in deeper sediment horizons. DNA- and RNA-based community profiles differed, although both approaches had similar community dynamics. Crenarchaeota showed the strongest shift in community composition in response to availability of labile POC, indicating that POC flux may have a more pronounced impact on crenarchaeal communities than on bacterial communities. The high number of phylotypes common to each sample time suggests that both standing stock and active prokaryotic communities are stable.
Highlights
Abyssal sediments at depths between 3000 and 6000 m cover 450% of the earth’s surface (Smith et al, 2009), comprising one of its largest biomes
The aim of the present study was to investigate whether the composition of ‘total’ and active prokaryotic communities in abyssal sediments changes temporally and whether such changes result from temporal variation in Particulate organic carbon (POC) flux to the abyssal seafloor
Separate binary matrices were constructed for bacterial and crenarchaeal Denaturing Gradient Gel electrophoresis (DGGE) gels, based on the presence or absence of operational taxonomic units (OTUs) and results were used to determine OTUs that were present in all samples from a particular sediment horizon and those shared between DNA- and RNA-targeted analyses in samples taken at all sampling times (June, September and February)
Summary
Abyssal sediments at depths between 3000 and 6000 m cover 450% of the earth’s surface (Smith et al, 2009), comprising one of its largest biomes. They were traditionally considered to be well buffered from seasonality and changing environmental conditions in the overlying water column (Druffel and Robinson, 1999; Menzies, 1965), and to have low process rates, because of the low temperature and organic nutrient input. Observation of seasonal and inter-annual variation in organic matter supply to the abyssal seafloor, linked to benthic productivity and oxygen consumption (Billett et al, 1983; Smith and Baldwin, 1984), challenged this view, and the close coupling of deep-sea benthic processes to surface water dynamics is well established.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Deep Sea Research Part I: Oceanographic Research Papers
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
