Challenges on salt marsh restoration: from seed to climate resilience

Salt marsh restoration can be considered an essential nature-based solution for coastal protection and climate change mitigation. However, restoration practices present a myriad of challenges, particularly in the journey from seed germination to achieving climate resilience, as response to challenges such as variable hydrology, and climate change impacts that can hinder seed establishment and growth. Effective restoration requires a deep understanding of the local ecology, the selection of native plant species, and adaptive management strategies to foster resilience against rising sea levels and shifting climate patterns. Active restoration is used less often than passive restoration, and involves improved seedling and planting techniques, with a drawback related to the physical damage done to healthy habitats through the collection of donor plants. A recent alternative solution to counter this destructive issue involves the installation of a plant nursery (mesocosms) for seed germination and plant production.

In this study, we present the experimental design and preliminary data on halophytes’ germination and seed propagation strategies, conducted in a mesocosm conditions.  Our goal is to assess the optimal abiotic conditions to initiate the germination process of Atriplex Portucaloides seeds (mid-high marsh species), collected at Ria de Aveiro coastal lagoon (centre Portugal). Simultaneously, this study provides valuable insights into the climate resilience of Sporobolus maritimus (low marsh species) under increasing flood conditions, framed within various sea-level rise scenarios. Through fieldwork experiments at the Ria Formosa lagoon (south Portugal), data on the plant's adjustments to prolonged hydroperiods have been recorded. Adjustments in growth patterns and survival rates of Sporobolus maritimus are crucial for understanding the plant's response to environmental changes and provide essential information for estimating the longevity of restored populations. By addressing these two challenges, the obtained results enhance knowledge and support the development of effective restoration strategies to enhance the resilience of coastal salt marsh ecosystems against climate change.

 

Keywords: salt marshes, halophyte nursery infrastructure, sea-level rise, field experiment, resilience.

 

Acknowledgments: This study had the support of the Fundação para a Ciência e Tecnologia (FCT), through the strategic projects UID/00350/2025 (CIMA), UID/50017/2025 (doi.org/10.54499/UID/50017/2025) and LA/P/0094/2020 (doi.org/10.54499/LA/P/0094/2020) (CESAM- Centro de Estudos do Ambiente e do Mar). Inês Carneiro by was supported by the PhD grant 2024.02443.BD, also funded by the FCT. Thanks are also due to FEDER - Fundo Europeu de Desenvolvimento Regional funds through the COMPETE 2030 and by Portuguese funds through FCT in the framework of the project COMPETE2030-FEDER-00929100 (BLUE-REWET).