Roots of marine forest recovery

Marine forests encompass a wide range of ecosystems, from macroalgal beds to seagrass meadows and coral reefs. They play critical roles in shaping both population and community dynamics of the biodiversity they support. However, due to several threats such as overgrazing, the introduction of non-indigenous species and climate change, marine forests at a considerable risk of decline. Their capacity to recover is under enormous strain with many solutions, whether temporary or permanent, forced to be explored in the realms of restoration. As an integral component of the NIS-RECOV project, we present preliminary results, performed in the framework of European projects (i.e. FORESCUE) on the potential for natural recovery of Cystoseira forests in the shallow coastal waters of the Mediterranean. We draw on a fundamental law observed in both plant and coral populations referred to as self-thinning, where density-dependent mortality drives individuals to compete, leading to natural reductions in density as an ecosystem matures. This concept suggests that marine forests, such as those formed by Cystoseira, may undergo similar self-regulating development that reduces density, potentially enhancing resource availability for surviving individuals. Through the application of self-thinning principles, we seek to understand if natural recovery patterns of Cystoseira forests align with these dynamics. As observed in other vulnerable ecosystems such as coral reefs, self-thinning can aid recovery, suggesting that this law may be somewhat universal for sessile, habitat forming organisms. We seek to determine whether self-thinning operates across diverse ecosystems and to understand the implications for forest structure. The insights from this research would offer valuable guidance for conservation and restoration efforts by informing strategies that harness natural recovery mechanisms rather than relying solely on artificial interventions. This approach has the potential to foster a more resilient Cystoseira forest in the face of environmental stressors and provide a foundation for sustainable management practices that prioritize ecosystem stability.