Ups and downs: copepods reverse the near-body flow to cruise in the water column.

Fuente: PubMed
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Autori principali: Tack, Nils B, Oliveira Santos, Sara, Gemmell, Brad J, Wilhelmus, Monica M
Natura: Artículo científico
Lingua:en
Pubblicazione: Marine biology 2024
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author Tack, Nils B
Oliveira Santos, Sara
Gemmell, Brad J
Wilhelmus, Monica M
author_facet Tack, Nils B
Oliveira Santos, Sara
Gemmell, Brad J
Wilhelmus, Monica M
Tack, Nils B
Oliveira Santos, Sara
Gemmell, Brad J
Wilhelmus, Monica M
collection PubMed - marine biology
contents Ups and downs: copepods reverse the near-body flow to cruise in the water column. Tack, Nils B Oliveira Santos, Sara Gemmell, Brad J Wilhelmus, Monica M Copepods are negatively buoyant organisms actively participating in large-scale vertical migrations as primary consumers in marine ecosystems. As such, these organisms need to overcome their own weight to swim upwards, incurring extra energy costs that are not offset by any mechanism intrinsic to drag-based propulsion. While copepod vertical migrations are well documented, it is still unclear how they achieve extensive upward cruising despite this limitation. In this study, we found suction to be a compensatory mechanism enhancing thrust in upward-swimming copepods. Using experimentally derived velocity and pressure fields, we observed that copepods pull water in front of them to generate sub-ambient pressure gradients when cruising upward, thereby inducing an upstream suction force to complement the thrust produced by the legs. Contrary to expectations that drag always dominates the leg recovery phase, we found that the upstream suction generates net thrust for about a third of the recovery stroke. In contrast, downward-swimming copepods push rather than pull on water and do not benefit from thrust-enhancing suction effects during the recovery stroke. Differences in the induced flows are associated with contrasting leg kinematics, indicating a response to the body orientation rather than a fixed effect. These results offer insights into an important swimming mechanism that can inform the role mesozooplankton play in biogenic hydrodynamic transport and its impact on marine biogeochemistry.
format Artículo científico
id pubmed_39398414
institution PubMed
language en
publishDate 2024
publisher Marine biology
record_format pubmed
spellingShingle Ups and downs: copepods reverse the near-body flow to cruise in the water column.
Tack, Nils B
Oliveira Santos, Sara
Gemmell, Brad J
Wilhelmus, Monica M
Ups and downs: copepods reverse the near-body flow to cruise in the water column. Tack, Nils B Oliveira Santos, Sara Gemmell, Brad J Wilhelmus, Monica M Copepods are negatively buoyant organisms actively participating in large-scale vertical migrations as primary consumers in marine ecosystems. As such, these organisms need to overcome their own weight to swim upwards, incurring extra energy costs that are not offset by any mechanism intrinsic to drag-based propulsion. While copepod vertical migrations are well documented, it is still unclear how they achieve extensive upward cruising despite this limitation. In this study, we found suction to be a compensatory mechanism enhancing thrust in upward-swimming copepods. Using experimentally derived velocity and pressure fields, we observed that copepods pull water in front of them to generate sub-ambient pressure gradients when cruising upward, thereby inducing an upstream suction force to complement the thrust produced by the legs. Contrary to expectations that drag always dominates the leg recovery phase, we found that the upstream suction generates net thrust for about a third of the recovery stroke. In contrast, downward-swimming copepods push rather than pull on water and do not benefit from thrust-enhancing suction effects during the recovery stroke. Differences in the induced flows are associated with contrasting leg kinematics, indicating a response to the body orientation rather than a fixed effect. These results offer insights into an important swimming mechanism that can inform the role mesozooplankton play in biogenic hydrodynamic transport and its impact on marine biogeochemistry.
title Ups and downs: copepods reverse the near-body flow to cruise in the water column.
url https://pubmed.ncbi.nlm.nih.gov/39398414/