Author(s): Abner Barnuevo; Takashi Asaeda
Linked Author(s): Takashi Asaeda
Keywords: No Keywords
Abstract: Mangrove forests are rapidly declining due to diverse threats caused by single, cumulative or synergistic processes arising from the human exploitation. As a respond to the alarming rate of declining mangrove, rehabilitation programs were designed and implemented to restore the damaged habitat. However, several projects were unsuccessful and suffered high mortality due to inappropriate species-site matching with the favorable environmental conditions. This study investigated the levels of oxidative stress of Rhizophora stylosa, an iconic mangrove species selected for rehabilitations, as a response to different salinity, inundation and submersion period in greenhouse condition. Mature propagules of similar sizes were collected in Olango Island, Cebu, Philippines and cultured in the greenhouse at Saitama University, Japan in different salinities (0,20,35ppt) and water levels, and subjected to varying inundation hydroperiod to determine its growth and physiological stress responses. Leaf tissues were analyzed for reactive oxygen species (ROS) specifically hydrogen peroxideantioxidative enzymes and pigments. Results of the study showed that salinity and inundation significantly induced the production of ROS and antioxidants in the leaves of R. stylosa. Submersion of the whole plant imposed a higher order magnitude of stress compared with the effect of salinity, and even caused sublethal damage when prolonged. Furthermore, submersion reduced the photosynthetic capacity which could translate into lower growth and productivity at the community level. The high ROS generation and the observed sublethal damage in the leaves of R. stylosa when in submerged condition could be a valuable input to its ecophysiology and site condition preference. Frequently flooded areas especially the seafront fringes that are subjected to longer submersion period at spring tides may suffer high levels of oxidative stress and poor survival.
Year: 2018