The Banc d′Arguin is a marine ecosystem of global conservation significance, the largest bird sanctuary of western Africa, supported by one of the most extensive seagrass beds in the world composed by three seagrass species, two temperate near their southern limit (Zostera noltei and Cymodocea nodosa) and one tropical at its northern limit (Halodule wrightii). Here we predict the fate of this seagrass ecosystem under climate change scenarios during the 21st century, using species distribution models and sea level rise estimates. We forecast a probable decline in total seagrass area of 3340 Km2 (78%) by 2100, involving the loss of both temperate seagrasses (Z. noltei, C. nodosa), the foundational ecosystem components. By 2050, only the tropical species (H. wrightii) would remain, which forms thin and sparse shallow stands functionally distinct from the previous tall dense meadows that span wider vertical ranges. Intertidal flats, the essential bird foraging habitats, would become unvegetated and also suffer a major reduction in area (114 km2 by 2050, 587 km2 by 2100). The large projected loss of foundational seagrass species portends a collapse of major ecosystem functions with profound impacts on biodiversity, fishery resources and ecosystem services.
Bibliographical noteKAUST Repository Item: Exported on 2021-11-15
Acknowledgements: We thank Nicolas Alemán and Jean-Paul Barusseau for providing the GIS data of the bathymetric map of the Banc d′Arguin, Hermanus Nicolaas Coertze for help in compiling occurrence data from the literature, and the support of the administration and staff of the PNBA-National Park of the Banc d′Arguin and IMROP-Mauritanian Fisheries and Oceanography Research Institute in the field surveys in the Banc d′Arguin. Help in field work was provided by many collaborators including Mohamed Bourweiss, Cheikhna Gandega, Sidi Mohamed Mahfoudh, Iveco Mohamed, Carolina de La Hoz Schilling, Nicolas Compain, Lucia Diaz, Joao Encarnação, David Abecasis, Paul Messialle, Mohamed Ayoub, Mohamed Cheddad, Mohamed Salem Hady, and Imraguen fishing crews. This study received funds from a Pew Marine Fellowship (EAS) and Portuguese national funds from FCT - Foundation for Science and Technology through UIDB/04326/2020 and SFRH/BSAB/150485/2019, and CRESC Algarve 2020 and COMPETE 2020 through projects EMBRC.PT ALG-01-0145-FEDER-022121 and BIODATA.PT ALG-01-0145-FEDER-022231. Additional support came from MAVA foundation project "PNBA-site emblématique pour les tortues", PRCM (Partenariat Régional pour la Conservation de la zone côtière et Marine en Afrique de l′Ouest) project "Survie des Tortues Marines” PRCM/STM POOOA4/OA9, and the EU Horizon 2020 under the Marie Skłodowska-Curie grant agreement Nº 894941 (to RMC) and Tropibio Era Chair (EU grant 854248 and NORTE-01-0145-FEDER-000046, for CIBIO).
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Nature and Landscape Conservation