Warming effect on nitrogen fixation in Mediterranean macrophyte sediment

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dc.contributor.author Garcias Bonet, Neus
dc.contributor.author Vaquer-Sunyer, Raquel
dc.contributor.author Duarte, Carlos M.
dc.contributor.author Marbà, Núria
dc.date.accessioned 2019-04-11T11:03:50Z
dc.date.available 2019-04-11T11:03:50Z
dc.identifier.uri http://hdl.handle.net/11201/149297
dc.description.abstract [eng] The Mediterranean Sea is warming faster than the global ocean, with important consequences for organisms and biogeochemical cycles. Warming is a major stressor for key marine benthic macrophytes. However, the effect of warming on marine N2 fixation remains unknown, despite the fact that the high productivity of macrophytes in oligotrophic waters is partially sustained by the input of new nitrogen (N) into the system by N2 fixation. Here, we assess the impact of warming on the N2 fixation rates of three key marine macrophytes: Posidonia oceanica, Cymodocea nodosa, and Caulerpa prolifera. We experimentally measured N2 fixation rates in vegetated and bare sediments at temperatures encompassing current summer mean (25 and 27 ∘C), projected summer mean (29 and 31 ∘C), and projected summer maximum (33 ∘C) seawater surface temperatures (SSTs) by the end of the century under a scenario of moderate greenhouse gas emissions. We found that N2 fixation rates in vegetated sediments were 2.8-fold higher than in bare sediments at current summer mean SST, with no differences among macrophytes. Currently, the contribution of N2 fixation to macrophyte productivity could account for up to 7 %, 13.8 %, and 1.8 % of N requirements for P. oceanica, C. nodosa, and C. prolifera, respectively. We show the temperature dependence of sediment N2 fixation rates. However, the thermal response differed for vegetated sediments, in which rates showed an optimum at 31 ∘C followed by a sharp decrease at 33 ∘C, and bare sediments, in which rates increased along the range of the experimental temperatures. The activation energy and Q10 were lower in vegetated than bare sediments, indicating the lower thermal sensitivity of vegetated sediments. The projected warming is expected to increase the contribution of N2 fixation to Mediterranean macrophyte productivity. Therefore, the thermal dependence of N2 fixation might have important consequences for primary production in coastal ecosystems in the context of warming.
dc.format application/pdf
dc.relation.isformatof Reproducció del document publicat a: https://www.biogeosciences.net/16/167/2019/
dc.relation.ispartof Biogeosciences, 2019, vol. 16, p. 167-175
dc.rights cc-by (c) Garcias Bonet, Neus et al., 2019
dc.rights.uri http://creativecommons.org/licenses/by/3.0/es
dc.subject.classification 57 - Biologia
dc.subject.other 57 - Biological sciences in general
dc.title Warming effect on nitrogen fixation in Mediterranean macrophyte sediment
dc.type info:eu-repo/semantics/article
dc.type info:eu-repo/semantics/publishedVersion
dc.date.updated 2019-04-11T11:03:50Z
dc.rights.accessRights info:eu-repo/semantics/openAccess

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cc-by (c) Garcias Bonet, Neus et al., 2019 Except where otherwise noted, this item's license is described as cc-by (c) Garcias Bonet, Neus et al., 2019

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