Assessing the Connectivity and Estimating the Blue Carbon Potential of Seagrass Meadows Along the Italian Coastline

Details

Supervisors

Hanert, Emmanuel

Faculty

Ecole polytechnique de Louvain

Degree label

Master [120] : ingénieur civil mécanicien, à finalité spécialisée

Abstract

Seagrass meadows are increasingly threatened by anthropogenic pressures worldwide. In the Mediterranean Sea, Posidonia Oceanica has already lost approximately 34 % of its historical distribution, and some studies predict its complete disappearance by 2100. In response to this decline, Mediterranean countries are developing conservation and restoration strategies aimed at protecting seagrass ecosystems. Assessing the potential connectivity among meadows through sexual propagule dispersal is therefore essential for understanding their resilience and recovery capacity. This thesis uses OpenDrift, an open-source Lagrangian particle tracking framework, to simulate the dispersal of Posidonia Oceanica propagules. The model incorporates three-dimensional transport processes, including current- and wind-driven advection, turbulent diffusion, and vertical mixing. The results reveal generally weak connectivity among Italian seagrass meadows, suggesting a limited potential for recolonization through sexual reproduction following local habitat loss. In a second stage, the modelling framework was adapted to simulate the transport of seagrass detrital fragments in order to quantify their contribution to blue carbon sequestration. The simulations allowed the estimation of carbon export towards deep-sea environments, where organic matter can be sequestered over long timescales. The exported biomass represents approximately 1 % of the net primary production. However, due to the extensive distribution of seagrass meadows along the Italian coastline, this still corresponds to an estimated annual sequestration flux of 10.701 kt C.y^(-1). The results support the implementation of both restoration and protection measures for seagrass meadows, owing to their relative vulnerability to disturbance and their valuable role in blue carbon sequestration.