Periodic sediment shift in migrating ripples influences benthic microbial activity

What is it about?

During the ripple migration induced by sediment transport, the microbial communities are, beside to high rate water exchange which stimulates their growth and activity, exposed to mechanical disruption of the biofilm on sand grains in transit which in turn decreases stream metabolism.

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Why is it important?

This study is the first experimental investigation on the effect of periodic disturbance on sediment metabolism in migrating sand ripples. It reveals that migration of ripples modifies sediment associated C-sequestration. Periodic sediment shift in migrating ripples results in significant disturbance on the microbial functions, decreasing the sediment associated microbial community respiration and the ability to mineralize particulate organic matter. The results refine previous suggestions which proposed shifting sands as general hotspot of microbial activity in rivers and indicate inference with organic matter quality. With the worldwide proliferation of migrating sand ripples due to massive catchment erosion, suppressed mineralization of organic matter will increasingly affect stream metabolism, downstream transport of organic matter and carbon cycling from reach to catchment scale.

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