Abstract
In marine environments, macrofauna living in or on the sediment surface may alter the structure, diversity and function of benthic microbial communities. In particular, microbial nitrogen (N)-cycling processes may be enhanced by the activity of large bioturbating organisms. Here, we study the effect of the burrowing mud shrimp Upogebia deltaura upon temporal variation in the abundance of genes representing key N-cycling functional guilds. The abundance of bacterial genes representing different N-cycling guilds displayed different temporal patterns in burrow sediments in comparison with surface sediments, suggesting that the burrow provides a unique environment where bacterial gene abundances are influenced directly by macrofaunal activity. In contrast, the abundances of archaeal ammonia oxidizers varied temporally but were not affected by bioturbation, indicating differential responses between bacterial and archaeal ammonia oxidizers to environmental physicochemical controls. This study highlights the importance of bioturbation as a control over the temporal variation in nitrogen-cycling microbial community dynamics within coastal sediments.
Highlights
Bioturbation – the physical and chemical disturbance of a sediment body by macrofauna or meiofauna – can impact upon microbial community dynamics within sediments
Shrimp burrows alter the temporal variability of specific microbial genes The quantitative polymerase chain reaction (q-PCR) was used to enumerate bacterial and archaeal 16S rRNA genes, as well as genes representing betaproteobacterial and archaeal ammonia oxidizers; bacterial denitrifiers and bacteria capable of the anammox process (Planctomycetes-specific 16S rRNA)
Sequence analysis showed that the Planctomycetes-specific 16S rRNA primers used here targeted anammox bacteria, as shown previously (Jayakumar et al, 2009; Hu et al, 2011; Sonthiphand and Neufeld, 2013); these samples are labelled as anammox 16S rRNA
Summary
Macrofauna living in or on the sediment surface may alter the structure, diversity and function of benthic microbial communities. We study the effect of the burrowing mud shrimp Upogebia deltaura upon temporal variation in the abundance of genes representing key N-cycling functional guilds. The abundance of bacterial genes representing different N-cycling guilds displayed different temporal patterns in burrow sediments in comparison with surface sediments, suggesting that the burrow provides a unique environment where bacterial gene abundances are influenced directly by macrofaunal activity. The abundances of archaeal ammonia oxidizers varied temporally but were not affected by bioturbation, indicating differential responses. This study highlights the importance of bioturbation as a control over the temporal variation in nitrogen-cycling microbial community dynamics within coastal sediments
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