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Ocean acidification and hypoxia alter organic carbon fluxes in marine soft sediments
Author(s) -
Ravaglioli Chiara,
Bulleri Fabio,
Rühl Saskia,
McCoy Sophie J.,
Findlay Helen S.,
Widdicombe Stephen,
Queirós Ana M.
Publication year - 2019
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1111/gcb.14806
Subject(s) - ocean acidification , hypoxia (environmental) , environmental science , oceanography , total organic carbon , blue carbon , effects of global warming on oceans , environmental chemistry , climate change , ecology , carbon sequestration , carbon dioxide , chemistry , geology , oxygen , global warming , biology , organic chemistry
Anthropogenic stressors can alter the structure and functioning of infaunal communities, which are key drivers of the carbon cycle in marine soft sediments. Nonetheless, the compounded effects of anthropogenic stressors on carbon fluxes in soft benthic systems remain largely unknown. Here, we investigated the cumulative effects of ocean acidification (OA) and hypoxia on the organic carbon fate in marine sediments, through a mesocosm experiment. Isotopically labelled macroalgal detritus ( 13 C) was used as a tracer to assess carbon incorporation in faunal tissue and in sediments under different experimental conditions. In addition, labelled macroalgae ( 13 C), previously exposed to elevated CO 2 , were also used to assess the organic carbon uptake by fauna and sediments, when both sources and consumers were exposed to elevated CO 2 . At elevated CO 2 , infauna increased the uptake of carbon, likely as compensatory response to the higher energetic costs faced under adverse environmental conditions. By contrast, there was no increase in carbon uptake by fauna exposed to both stressors in combination, indicating that even a short‐term hypoxic event may weaken the ability of marine invertebrates to withstand elevated CO 2 conditions. In addition, both hypoxia and elevated CO 2 increased organic carbon burial in the sediment, potentially affecting sediment biogeochemical processes. Since hypoxia and OA are predicted to increase in the face of climate change, our results suggest that local reduction of hypoxic events may mitigate the impacts of global climate change on marine soft‐sediment systems.