Response to salinity-induced oxidative stress in Ceratophyllum demersum L. (Ceratophyllaceae)

Abstract

[eng] Marine intrusion is a major threat for wetland ecosystems, mainly inhabited by macrophytes. Increase in salinity levels due to marine intrusion can cause an increase in Reactive Oxygen Species (ROS) production in macrophytes. ROS react with biomolecules causing oxidative damage, which is prevented by both enzymatic and nonenzymatic antioxidant mechanism. Macrophyte response to salinity has been proposed for monitoring marine intrusion. Ceratophyllum demersum, a subcosmopolitan submerged macrophyte reported to be salinity sensitive, inhabits the brackish waters of s’Albufera de Mallorca, the highest wetland of the Balearic Islands. Enzymatic antioxidant activities, malondialdehyde (MDA) concentration and photosynthetic pigments content were measured in C. demersum following a salinity gradient through five stations in s’Albufera de Mallorca. Salinity triggered superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione reductase (GRd) activities, but they failed to avoid oxidative damage (MDA concentrations increased) at the highest salinity levels. Evolution of photosynthetic pigments contents and ratios did not follow the salinity gradient, suggesting they would depend on other environmental factors. The parameters measured in C. demersum were not robust enough to be used as biomarkers for monitoring marine intrusion. Reviewing the literature, M. spicatum coverage would be a better parameter for monitoring marine intrusion. Further studies at local level should be carried out to a better understanding of macrophyte and wetland ecosystems response to marine intrusion.