Sei qui: HomeStaffStaffITALIANODottorati Open University (PhD) 6. Multiple stressors response in the seagrass Posidonia oceanica

Department of Integrative Marine Ecology
Director of Studies: Dr. Gabriele Procaccini


Despite their key ecological value, coastal ecosystems such as seagrass meadows are experiencing a progressive decline, due to a number of threats associated to human activities along the coastline, as well as climate changes. In the Mediterranean, the marine angiosperm Posidonia oceanica forms dense meadows, which provide important ecological functions and services, being crucial for maintaining the quality of coastal waters, for the cycling of nutrients, for stabilizing sediments and reducing shoreline erosion. The conservation of P. oceanica meadows has become a key objective on actual European environmental and water policies. They are protected at the European level, as a priority habitat (Habitats Directive, Dir 92/43/CEE and Directive 97/62/CE) and as a species (Bern Convention, Annex 1), and are under specific legal protection actions in several European countries. Policies aiming at improving quality of coastal waters and marine environments across Europe are also being developed in European countries (Water Framework Directive and Marine Strategy Framework Directive), recognizing the large potential of P. oceanica meadows as bioindicators of ecological quality. In this context, investigation of the effects of climate and non-climate stressors in P. oceanica became crucial, in order to determine both the physiological response, and the potential adaptive response of the species. Effects of single environmental drivers (i.e. light, temperature and CO2) have been studied in different seagrass species, both in natural and controlled conditions. Nonetheless, in natural environments, those drivers often do not act in isolation, but additive, synergistic or antagonistic effects can occur. This PhD project aims to investigate the effects of "multiple stressors" in Posidonia oceanica. The combined effects of pairs of factors (e.g. Temperature vs. Light; Temperature vs. CO2 and Light vs. CO2) will be investigated looking at the expression of target genes selected in previous single-stressor studies, via RT-qPCR. The photophysiological response will also be assessed looking at changes in the pigmentary pool, as well as characterizing the functionality and structure of the photosynthetic apparatus through chlorophyll a fluorescence measures. Changes in the morphology of the plants will also be considered in the project, as well as changes in some plant fitness traits. Finally, changes in the epiphytic community on rhizomes and leaves will be assessed in order to get an insight into potential indirect effects of stressors on P. oceanica. Experiments will be carried out in the new benthic mesocosm facility available at the SZN.
Project results will be useful for designing new management strategies of coastal resources in two different ways. First, allowing to move away from the impact-by-impact framework, to which management processes are strongly focused. Second, providing new generation of early warning indicators for environmental assessment.

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