A study has resulted in the transplantation of 384 m² of Posidonia oceanica seagrass on the scale of an industrial project as part of maritime works in Monaco. This success challenges the idea that these ecosystems are "non-transplantable". This unprecedented experiment, conducted over a period of eight years, opens up new prospects for the preservation of seagrass meadows threatened by coastal urbanisation.
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s part of the construction project for the "Mareterra" district in Monaco, the marine works involved the destruction of several hectares of Posidonia oceanica meadows, an underwater plant essential to the Mediterranean ecosystem. To limit this impact, Andromède Océanologie and the University of Liège set up an unprecedented large-scale transplantation operation.

Localisation of Posidonia oceanica donor meadow (1) Larvotto transplantation zone (2) Nearby meadow of reference (3) Distant meadow of reference (4) Distant meadow of reference at the lower limit (5) In blue the area of the construction project. | ©️ Andromède Océanologie
The experiment began in 2017 with the relocation of 384 m² of seagrass beds from the construction zone to the Larvotto marine reserve. The technique used, known as "clod" transplantation, enabled the roots and associated substrate to be preserved intact, giving the plants a better survival rate. The study validated an operational technique capable of transplanting large areas of seagrass in record time, a major step forward in preserving these fragile ecosystems.
For eight years, rigorous monitoring was carried out to observe the resilience of the transplanted meadows," explains Sylvie Gobert, an oceanologist at ULiège. Despite major marine works carried out nearby, the transplanted meadow showed remarkable resilience, with health indicators rapidly approaching those of the neighbouring natural meadows." Three years after transplanting, both the transplanted and natural seagrass beds were flowering. After eight years, the surface area of the transplanted seagrass had exceeded the area initially transplanted, recording an expansion of 25.8% in 2024. "These results validate the idea that transplanting is a viable and ecologically relevant alternative as a mitigation measure in coastal development projects."

Removal platform and Optimal tree spade transplanter. Transport baskets (1), long-arm excavator (2), Jack-up platform (3), platform anchoring lest (4), control cameras (5), expected sods with targets (6), laser pointer (7), transplanting machine (8), baskets lift (9). Below : Iron and coco fiber transport basket | ©️ Andromède Océanologie
This experience is revolutionising the way in which seagrass conservation is approached in coastal development projects. Until now, the destruction of seagrass beds was considered irremediable, and compensatory measures were often limited to the installation of artificial reefs. However, this study proves that transplantation is a viable alternative that should be fully integrated into environmental conservation strategies.
Long-standing expertise
The University of Liège played a central role in this study thanks to the expertise of its researchers, in particular Professor Sylvie Gobert and Arnaud Boulenger. A specialist in marine ecology, Sylvie Gobert provided a scientific perspective that was essential for assessing the viability of the transplantation and ensuring rigorous monitoring of the physiological and structural parameters of the meadows. Arnaud Boulenger, a doctoral student at the Biological Oceanography Laboratory, helped analyse the data and set up the monitoring protocols.
The Biological Oceanography Laboratory at the University of Liège has leading expertise in the study and preservation of seagrass beds, dating back to the 1970s. This long tradition of research is based in particular on observations made at the STARESO, the underwater and oceanographic research station of the University of Liège, located in Corsica, in a protected marine area. For more than fifty years, this station has been studying the evolution of Posidonia oceanica meadows under natural conditions, providing unique and valuable data on their growth, resilience and ecological role. Thanks to the work carried out on this exceptional site, ULiège has developed in-depth knowledge of the dynamics of the meadows and the best strategies for their conservation and restoration. This expertise was a major asset in ensuring the success of the transplantation project in Monaco, by guaranteeing a rigorous protocol and a detailed scientific assessment of the long-term results.
The success of this experiment calls into question current practices and paves the way for better management of marine ecosystems. "By integrating transplantation as a mitigation measure in coastal development projects, it becomes possible to significantly reduce the environmental impact while preserving these precious habitats for Mediterranean biodiversity," concludes Sylvie Gobert.

Transplants in the Larvotto transplantation zone in July 2024. | ©️ Andromède Océanologie

Scientific reference

Pierre Descamp, Sébastien Personnic, Sylvie Gobert, Arnaud Boulenger, Michèle Leduc, Gwenaelle Delaruelle, Adèle Barroil, Guilhem Marre, Florian Holon, Julie Deter, Seagrass sod transplantation: A relevant tool for preventing the destruction of meadows in coastal construction projects, Environmental Challenges, avril 2025. doi:10.1016/j.envc.2025.101087 (published in Open Access)
This content is taken from University of Liège

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Cite This Article as

"Transplanting Posidonia oceanica: a major scientific advance for the conservation of seagrass meadows", MachPrinciple, May 27, 2025, https://machprinciple.com/post/Transplanting-Posidonia-oceanica-a-major-scientific-advance-for-the-conservation-of-seagrass-meadows