Posidonia oceanica mats as palaeoecological tools for the conservation and management of two western Mediterranean protected areas
ID: 613 / 387
Proposed Symposium Title: Posidonia oceanica mats as palaeoecological tools for the conservation and management of two western Mediterranean protected areas
Lourdes López-Merino1*, Carmen Leiva-Dueñas2, Miguel A. Mateo2, Antonio Martínez Cortizas4
Affiliations: 1 Universidad Complutense de Madrid, Madrid, Spain 2 Aarhus University, Aarhus C, Denmark 3 Centro de Estudios Avanzados de Blanes, Consejo Superior de Investigaciones Científicas (CEAB-CSIC), Blanes, Spain 4 Universidade de Santiago de Compostela, Santiago de Compostela, Spain * Corresponding author e-mail: firstname.lastname@example.org
Worldwide, seagrass meadows are significant carbon sinks, but their rapid decline, attributed to increased anthropogenic pressure and global change, poses a threat to ecosystem services. To unravel the long-term dynamics of these unique ecosystems and preserve them, we employed a multi-proxy palaeoecological approach in Mediterranean Posidonia oceanica meadows within two protected areas in Spain: Cape Creus Natural Park and Cabrera National Park.
In Cape Creus, we conducted palynological, microcharcoal, magnetic susceptibility, and glomalin-related soil protein analyses on a P. oceanica mat. The findings indicate that climate and land-use changes in the Western Mediterranean have led to increased loadings of terrigenous material in the coastal zone since the Late Holocene, potentially impacting the carbon sink dynamics of the meadows. Additionally, geochemical, and sedimentological analyses on the mat, along with the C and N isotopic composition of P. oceanica sheaths, suggest that cumulative anthropogenic stressors since Roman times may have begun affecting ecosystem resilience, dynamics, and productivity, with more pronounced regime shifts during the last millennium.
In Cabrera, we investigated the composition of primary producers within several meadows at two bays, considering plausible local and global regulatory factors to assess the environmental drivers of change. This was achieved through fossil pigment, dinocyst, geochemical, and sedimentological analyses. Overall, our results suggest that historical and spatial variations in seagrass meadows' phototrophic community composition were influenced by the interaction between local factors (catchment-bay characteristics) and global climate processes (energy influx). Finally, palynological, magnetic susceptibility, and microcharcoal data on the same mats reconstruct landscape changes that affected the catchment and, consequently, the marine ecosystem.
As a key takeaway, efforts toward seagrass habitat restoration should address not only local coastal anthropogenic disturbances but also mainland/inland influences and climate impacts, recognising that meadow ecosystem structure responds to human impact and global change.