Publication Date:
2023-03-08
Description:
© The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Schmidt, C., Geslin, E., Bernhard, J. M., LeKieffre, C., Svenning, M. M., Roberge, H., Schweizer, M., & Panieri, G. Deposit-feeding of Nonionellina labradorica (foraminifera) from an Arctic methane seep site and possible association with a methanotroph. Biogeosciences, 19(16), (2022): 3897–3909, https://doi.org/10.5194/bg-19-3897-2022.
Description:
Several foraminifera are deposit feeders that consume organic detritus (dead particulate organic material with entrained bacteria). However, the role of such foraminifera in the benthic food web remains understudied. Foraminifera feeding on methanotrophic bacteria, which are 13C-depleted, may cause negative cytoplasmic and/or calcitic δ13C values. To test whether the foraminiferal diet includes methanotrophs, we performed a short-term (20 h) feeding experiment with Nonionellina labradorica from an active Arctic methane-emission site (Storfjordrenna, Barents Sea) using the marine methanotroph Methyloprofundus sedimenti and analysed N. labradorica cytology via transmission electron microscopy (TEM). We hypothesised that M. sedimenti would be visible post-experiment in degradation vacuoles, as evidenced by their ultrastructure. Sediment grains (mostly clay) occurred inside one or several degradation vacuoles in all foraminifers. In 24 % of the specimens from the feeding experiment degradation vacuoles also contained bacteria, although none could be confirmed to be the offered M. sedimenti. Observations of the apertural area after 20 h incubation revealed three putative methanotrophs, close to clay particles, based on bacterial ultrastructural characteristics. Furthermore, we noted the absence of bacterial endobionts in all examined N. labradorica but confirmed the presence of kleptoplasts, which were often partially degraded. In sum, we suggest that M. sedimenti can be consumed via untargeted grazing in seeps and that N. labradorica can be generally classified as a deposit feeder at this Arctic site.
Description:
This research has been supported by the French scientific programme MOPGA (Make our Planet Great Again) managed by the National Research Agency; the Norwegian Research Council through the Centre for Arctic Gas Hydrate, Environment and Climate (project number 223259); NORCRUST (project number 255250); and by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – 444059848.
Repository Name:
Woods Hole Open Access Server
Type:
Article
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