Looking back on the mission conducted at the end of February on the 
“Posidonium” in the waters of the Port-Cros National Park with the dream team Dr. Heike Molenaar, Stéphane Jamme, and Jean-Michel Cottalorda.
This “Posidonium” has an unusual history. From 1988 to 1995, over 300 cuttings from 13 different origins and more than 200 germinated seeds of Posidonia oceanica from 4 different origins were transplanted by Dr. Molenaar in the Palud cove, within the Port-Cros National Park. This collection of strains was named “Posidonium” by Professor Alexandre Meinesz in 1993, and today covers an area of nearly 625 m² and brings together 17 different Posidonia strains from 7 Mediterranean countries.
At the end of 2022, a massive flowering of Posidonia meadows was observed throughout the Mediterranean. Exceptionally high rates of flowering density were observed. Since then, fruits have started to develop in many inflorescences with significant rates of fruiting 
suggesting that fertilization has been effective. Thus, from March onwards, a large number of fruits should detach from the plants and disperse throughout the Mediterranean.
This mission allowed us to measure the expansion of each strain since the last mapping conducted in 2012 and to quantify leaf density
, flowering and fruiting to assess whether variations are present among the different Posidonium strains.
