BUSCADOR RECOLECTA

Digital.CSIC. Repositorio Institucional del CSIC

oai:digital.csic.es:10261/295930

16 pages, 7 figures, supporting information https://doi.org/10.1002/lno.12286.-- Data availability statement: All relevant data are within the paper and its Supporting Information file, Dissolved organic carbon (DOC) plays an essential role in the global marine carbon cycle, with coastal vegetated communities as important DOC producers. However, the ultimate fate of this DOC remains still largely unknown due to the lack of knowledge about its chemical composition and lability. Furthermore, global change could alter both DOC fluxes and its bioavailability, affecting the carbon sequestration capacity of coastal vegetated communities. This study explores, in two contrasting seasons (winter and summer), the effects of an in situ simulated marine heatwave on carbon metabolism and DOC fluxes produced by seagrass (Cymodocea nodosa) and macroalgae (Caulerpa prolifera) communities. In addition, the fluorescent characteristics and biodegradability of the dissolved organic matter released directly by the communities under such conditions are evaluated. Under marine heatwave conditions, a significant increase in net community production (NCP) in C. nodosa and a shift to negative DOC fluxes in C. prolifera were observed. In control treatments, the seagrass-dominated community produced a substantial amount of labile (between 44% and 58%) and recalcitrant DOC (between 42% and 56%), while C. prolifera community produced mainly recalcitrant DOC (between 64% and 87%). Therefore, this research revealed that temperature is an important factor determining the NCP in benthic communities and the chemical structure and bioavailability of DOC produced by these communities, since both communities tended to produce more humic-like and less bioavailable DOC with increasing temperature, This study has been supported by the Spanish National Project PAVAROTTI (CTM2017-85365-R); by SER-CADY project (FEDER-UCA18-107451). This project was co-financed by the European Union under the 2014–2020 ERDF Operational Programme and by the Department of Economic Transformation, Industry, Knowledge, and Universities of the Regional Government of Andalusia; by the Spanish National Project RECOUNT (PID2020-120237RJ-I00). This project was financed by MCIN/AEI/10.13039/501100011033, With the institutional support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), Peer reviewed