Effect of Ibuprofen on the germination niche of halophyte species

Halophytes are the main plant species of salt marshes, which are one of the most important habitats worldwide due to their ecological value and economic benefits. Pharmaceutical pollution has recently become one of the major human-induced threats to the natural environment. However, the effects of pharmaceutical pollution on plants are still unexplored. This research aimed to investigate the effect of Ibuprofen, one of the most common pharmaceuticals found in water bodies, on salt marshes plants. A negative effect of emergent pollutants like Ibuprofen on germination percentage or germination timing can potentially affect species population dynamics, and consequently, the integrity of salt marshes plant communities. To this aim, the best germination condition was selected for 4 halophyte species (Juncus acutus, Limonium vulgare, Sarcocornia fruticosa, Tripolium pannonicum). Then, seeds of the best germination species (Juncus acutus and Limonium vulgare) were sown in the Petri dishes at different concentrations of Ibuprofen (0, 2, 20, 200, and 2000 µg /l), and to combined solutions of NaCl + Ibuprofen. After 45 days of observation, to investigate seed ability to recover after salinity and Ibuprofen stress, recovery tests were carried out, by watering seed with fresh water only. Results showed that the best germination percentage, germination speed, and germination synchrony were in the control for both species J. acutus and L. vulgare. In J. acutus, Ibuprofen alone slightly decreased the germination percentage, speed, and synchrony, although not significantly. In L. vulgare, the pattern was less clear and less linear, showing non-significant effects at a concentration between (20 and 200 µg /l). Salinity significantly affected germination percentage, speed, and synchrony, both alone and in combination with Ibuprofen in both species. It completely inhibited the germination in J. acutus, while L. vulgare could germinate with low percentages (about 10 %). Nevertheless, recovery tests have shown that although with fluctuating patterns, seeds can recover from salinity, also when exposed to Ibuprofen. As a general pattern, we found that Ibuprofen had different effects on the two species, although they were non-significant for both species. It seems not to have interacted with salinity, while NaCl was a strong inhibitor of germination. This research for the first time empirically tested the effect of emergent pollutants such as Ibuprofen on the regeneration of wild species and provided important insight to understand plant dynamics, and their responses under new human- induced threats, such as contamination by emergent pollutants.