Balance Between Biomixing and Bioirrigation Behavior Controls Benthic Metal Efflux in Temperate Swedish Fjords
Abstract
Iron and manganese availability limits marine primary production in large parts of the ocean and exerts a strong influence on the global climate. Transitional systems such as fjords can control metal transport to the shelf by acting as metal sinks through burial or metal sources by releasing metals from less reactive metal oxides by benthic recycling. Benthic metal cycling is promoted by bioturbation by macrobenthos, which rework the sediment (‘biomixing’) and ventilate their burrows (‘bioirrigation’). The specific role of bioturbation in pore water mobilization, benthic efflux, or burial of metals in fjords is poorly constrained. Here, we investigated the bioturbation mode and potential to mobilize metals in three fjord systems with different environmental conditions in southwestern Sweden using a combined field sampling and modeling approach. We show that the extent to which the bioturbation zone overlaps with the microbial metal reduction zone in the sediments, together with the ratio of biomixing versus bioirrigation rates, determined whether the studied transitional system acted as a sink or source for metals. The efficiency of pore water mobilization of metals was primarily controlled by benthic metal recycling and subsurface oxidation. Including the bioturbation mode and its attenuation depth is thus critical for future investigations of benthic metal cycling, efflux and transport in transitional systems.
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BibTeX
@article{wittig2026balance,
title = {{Balance Between Biomixing and Bioirrigation Behavior Controls Benthic Metal Efflux in Temperate Swedish Fjords}},
author = {Cathrin Wittig and Martine Leermakers and Per O. J. Hall and Astrid Hylén and Mikhail Kononets and Ulrike Braeckman and Sebastiaan J van de Velde},
journal = {Journal of Geophysical Research: Biogeosciences},
year = {2026},
month = oct,
doi = {10.1029/2026jg010194},
url = {https://hal.science/hal-05820512v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Balance Between Biomixing and Bioirrigation Behavior Controls Benthic Metal Efflux in Temperate Swedish Fjords
AU - Cathrin Wittig
AU - Martine Leermakers
AU - Per O. J. Hall
AU - Astrid Hylén
AU - Mikhail Kononets
AU - Ulrike Braeckman
AU - Sebastiaan J van de Velde
PY - 2026
DA - 2026/10/17
JO - Journal of Geophysical Research: Biogeosciences
DO - 10.1029/2026jg010194
UR - https://hal.science/hal-05820512v1
AB - Iron and manganese availability limits marine primary production in large parts of the ocean and exerts a strong influence on the global climate. Transitional systems such as fjords can control metal transport to the shelf by acting as metal sinks through burial or metal sources by releasing metals from less reactive metal oxides by benthic recycling. Benthic metal cycling is promoted by bioturbation by macrobenthos, which rework the sediment (‘biomixing’) and ventilate their burrows (‘bioirrigation’). The specific role of bioturbation in pore water mobilization, benthic efflux, or burial of metals in fjords is poorly constrained. Here, we investigated the bioturbation mode and potential to mobilize metals in three fjord systems with different environmental conditions in southwestern Sweden using a combined field sampling and modeling approach. We show that the extent to which the bioturbation zone overlaps with the microbial metal reduction zone in the sediments, together with the ratio of biomixing versus bioirrigation rates, determined whether the studied transitional system acted as a sink or source for metals. The efficiency of pore water mobilization of metals was primarily controlled by benthic metal recycling and subsurface oxidation. Including the bioturbation mode and its attenuation depth is thus critical for future investigations of benthic metal cycling, efflux and transport in transitional systems.
SN - 2169-8953
ER -