Benthic biology influences sedimentation in submarine channel bends: Coupling of biology, sedimentation and flow

Date

2024-01-29

Author

Azpiroz-Zabala, M.
Sumner, E. J.
Cartigny, M. J. B.
Peakall, J.
Clare, M. A.
Darby, S. E.
Parsons, D. R.
Dorrell, R. M.
Özsoy, Emin
Tezcan, Devrim
Wynn, R. B.
Johnson, J.

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Submarine channels are key features for the transport of flow and nutrients into deep water. Previous studies of their morphology and channel evolution have treated these systems as abiotic, and therefore assume that physical processes are solely responsible for morphological development. Here, a unique dataset is utilised that includes spatial measurements around a channel bend that hosts active sediment gravity flows. The data include flow velocity and density, alongside bed grain size and channel-floor benthic macrofauna. Analysis of these parameters demonstrate that while physical processes control the broadest scale variations in sedimentation around and across the channel, benthic biology plays a critical role in stabilising sediment and trapping fines. This leads to much broader mixed grain sizes than would be expected from purely abiotic sedimentation, and the maintenance of sediment beds in positions where all the sediment should be actively migrating. Given that previous work has also shown that submarine channels can be biological hotspots, then the present study suggests that benthic biology probably plays a key role in channel morphology and evolution, and that these need to be considered both in the modern and when considering examples preserved in the rock record. This work first integrates flow data, sediment and biota for a subaqueous channel showing clear feedbacks between them. We suggest that biota can play a major role in sedimentation within submarine channels. Therefore, the assumption that submarine channels are abiotic should be discarded, which directly impacts on palaeoflow characteristics in ancient sediments.image

URI

https://hdl.handle.net/11511/108692

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Graduate School of Marine Sciences, Article