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Seagrass meadows are increasingly threatened by anthropogenic activities and climate change, necessitating restoration efforts such as cutting transplantation. Understanding the complex interactions between plant morphology and physiology is crucial for designing robust restoration strategies and assessing the success of transplantation and recovery processes. A pilot transplantation experiment with the Mediterranean seagrass Posidonia oceanica (L.) Delile was conducted in Northwestern Corsica (Calvi, France) to evaluate the feasibility of meadows degraded due to boat anchoring. The effects of the cuttings' origin and transplanting depth were investigated. The establishment success of transplanted fragments was assessed by investigating the photo-physiological parameters, carbohydrate content, and biometric parameters of both transplanted and control plants one year after transplantation at depths of 20 and 28 m. After one year, there was a high survival rate (90%) of the transplants, but their leaf surface area and biomass were significantly reduced compared to the control plants. Photosynthetic activity remained consistent between both depths, emphasizing the ability of P. oceanica cuttings to acclimate to a new light environment in a relatively short period of time (<3 months). Furthermore, light-harvesting pigments, photoprotective pigments, and carbohydrate concentration were greater at the deeper sites. This implies that transplantation at greater depths might be more effective. Furthermore, additional research is necessary to enhance our understanding of the relationship between photosynthesis and the overall health of the plant. This study emphasizes the essential integration of morphological and physiological investigations to offer an ecologically meaningful understanding of how marine ecosystems respond to various restoration methods. [ABSTRACT FROM AUTHOR]

This study provides a baseline describing natural small scale variability of Symbiodinium density in the sentinel coral Acropora globiceps during the summer, under non-bleaching conditions. Spatial scales investigated range from the colony scale (1–10 cm, i.e. among branches of the same colony) to the reef scale (1–10 km, i.e. among stations distributed over several locations and depths), at Moorea Island, French Polynesia. The coral–Symbiodinium symbiosis is a key process in scleractinian coral physiology, and Symbiodinium density provides an easy-to-measure and inexpensive biomarker of this symbiosis health. Spatial variability of three major environmental factors: light intensity, sedimentation and water motion was also assessed to evaluate their potential link with Symbiodinium density. Density of Symbiodinium did not significantly differ within colonies or among colonies within a station. However, a marked depth gradient was observed, showing increasing density with increasing depth and decreasing light intensity. These observations provide an interesting reference for forthcoming comparisons with disturbed conditions, such as bleaching events. [ABSTRACT FROM PUBLISHER]

Recovery of coral after bleaching episodes is a critical period for the health of the reef ecosystem. While events such as symbiont (genus Symbiodinium) shifting/shuffling or tissue apoptosis have been demonstrated to occur following bleaching, little is known concerning tissue recovery or cell proliferation. Here, we studied the sea anemone Aiptasia pallida exposed to a transient elevation of water temperature combined with high illumination (33°C and 1900 µmolphotons.m−2.s−1 for 30h). Following such treatment bleached anemones showed a significant reduction of their Symbiodinium density. Cell proliferation in the ectodermis and gastrodermis was determined by assessing the densities of cells labeled with a thymidine analogue (EdU). Cell proliferation significantly increased during the first day following stress in both tissue types. This increased cell proliferation returned to pre-stress values after one week. Although cell proliferation was higher in the ectodermis in absence of stress, it was relatively more pronounced in the gastrodermis of stressed anemones. In addition, the ratio of ectodermal mucocytes significantly increased three weeks after induced stress. These results suggest that thermal/photic stress coupled with the loss of the symbionts is able to enhance cell proliferation in both gastrodermis and ectodermis of cnidarians. While new cells formed in the gastrodermis are likely to host new Symbiodinium, the fate of new cells in the ectodermis was only partially revealed. Some new ectodermal cells may, in part, contribute to the increased number of mucocytes which could eventually help strengthen the heterotrophic state until restoration of the symbiosis. [ABSTRACT FROM AUTHOR]