João N. Franco, Stephanie D’agata, Diana Deyanova, Martin Gullström, Maria E. Asplund, Samantha N. Ridgway, Mats Björk, Leah Glass, Linus Hammar, Volanirina Ramahery, Diana Perry, Arielle I. Hoamby, Martin Dahl, Rashid O. Ismail, Hans W. Linderholm, Ariane Arias-Ortiz, Jamal Angelot Mahafina, Lina M. Rasmusson, Gloria Salgado Gispert, Liberatus D. Lyimo, Pere Masqué, University of Gothenburg (GU), Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Ecologie marine tropicale des océans Pacifique et Indien (ENTROPIE [Nouvelle-Calédonie]), Institut de Recherche pour le Développement (IRD [Nouvelle-Calédonie])-Ifremer - Nouvelle-Calédonie, Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de la Nouvelle-Calédonie (UNC), School of Natural Sciences and Centre for Marine Ecosystems Research, Edith Cowan University, and EDITH COWAN UNIVERSITY-EDITH COWAN UNIVERSITY
The study is part of the 4-year Blue Forests Project, initiated by the United Nations Environment Programme (UNEP) and partly funded by the Global Environment Facility (GEF). We thank the Swedish International development Cooperation Agency—Sida, marine bilateral programme for funding the participation of ROI and LDL. Funding was provided to PM through an Australian Research Council LIEF Project (LE170100219) and by the Generalitat de Catalunya (Grant 2017 SGR-1588). This work is contributing to the ICTA ‘‘Unit of Excellence’’ (MinECo, MDM2015-0552). Funding for MD was provided by the Bolin Centre for Climate Research. AA-O was supported by ‘‘Obra Social la Caixa’’ (LCF/BQ/ES14/10320004) and subsequently by the NOAA C&GC Postdoctoral Fellowship administered by UCAR-CPAESS (#NA18NWS4620043B). The IAEA is grateful for the support provided to its Environment Laboratories by the Government of the Principality of Monaco. Context: Seagrass meadows act as efficient natural carbon sinks by sequestering atmospheric CO2 and through trapping of allochthonous organic material, thereby preserving organic carbon (Corg) in their sediments. Less understood is the influence of landscape configuration and transformation (land-use change) on carbon sequestration dynamics in coastal seascapes across the land–sea interface. Objectives: We explored the influence of landscape configuration and degradation of adjacent mangroves on the dynamics and fate of Corg in seagrass habitats. Methods: Through predictive modelling, we assessed sedimentary Corg content, stocks and source composition in multiple seascapes (km-wide buffer zones) dominated by different seagrass communities in northwest Madagascar. The study area encompassed seagrass meadows adjacent to intact and deforested mangroves. Results: The sedimentary Corg content was influenced by a combination of landscape metrics and inherent habitat plant- and sediment-properties. We found a strong land-to-sea gradient, likely driven by hydrodynamic forces, generating distinct patterns in sedimentary Corg levels in seagrass seascapes. There was higher Corg content and a mangrove signal in seagrass surface sediments closer to the deforested mangrove area, possibly due to an escalated export of Corg from deforested mangrove soils. Seascapes comprising large continuous seagrass meadows had higher sedimentary Corg levels in comparison to more diverse and patchy seascapes. Conclusion: Our results emphasize the benefit to consider the influence of seascape configuration and connectivity to accurately assess Corg content in coastal habitats. Understanding spatial patterns of variability and what is driving the observed patterns is useful for identifying carbon sink hotspots and develop management prioritizations. info:eu-repo/semantics/publishedVersion