[A-CG40] Coastal Ecosystems 2. Coral reefs, seagrass and macroalgal beds, and mangroves

[ACG40-03] Integrated Modelling and Mapping for Assessing Red Sea Coastal Ecosystem Vulnerability to Multiple Stressors

*Ahmed Eladawy^1,2, Takashi Nakamura¹ (1.School of Environment and Society, Tokyo Institute of Technology, Ookayama 2-12-1 W8-5, Meguro, Tokyo, 152-8552, Japan. E-mails: [e-mail], 2.Irrigation and Hydraulics Engineering Dept., College of Engineering, Mansoura University, Egypt, 60 Elgomhoria Street - Mansoura, 35516, Egypt.)

Keywords:Red Sea , Corals , ROMS , Heat Waves , Nesting

The Red Sea has a rich marine ecosystem that has high economic, environmental, and cultural values. The purpose of our current research is to develop an integrated framework for the long-term conservation and management of the coastal and marine resources of Egyptian and Saudi Arabian coastal zones, which have been suffering from various stressors. Our research includes two main pathways, firstly investigating the unparalleled thermal tolerance of Red Sea coral reefs despite exposure to prolonged heat waves, suggesting that the northern Red Sea region will remain a coral refugia. Secondly, developing a validated high-resolution regional and nested ROMS models for two coral hotspots under extensive tourism development namely Hurghada Region (Egypt), and NEOM (Saudi Arabia). Our research results including long-term field observation of bleaching extent to check the hypothesis that the natural coral selection process occurred 6–7 kyr BP and corals could have quite similar real thresholds over the Red Sea. We adjusted the thermal thresholds to minimum 30°C, 31°C, and 32°C to recalculate degree heat weeks (DHWs) along the Red Sea. We then investigated whether the spatial distribution of the recalculated DHWs could explain coral susceptibility to bleaching. Further, we used representative concentration pathway (RCP) scenarios to predict when the water temperature will reach hypothetical thresholds and whether the northern Red Sea will continue to provide coral refugia. Despite a higher current linear warming trend, our analysis suggested that the sea surface temperature (SST) will increase by 2°C in the northern region (the least of all regions) by 2075–2085 under a business-as-usual scenario, compared to 2055 under current trends. In addition, for further investigation of other local cooling mechanisms that could also justify this unparallel response, an offline nesting approach was followed along with 30 vertical sigma layers for a five-year simulation on TSUBAME 3.0 in Tokyo Tech. The regional model results show a unique cooling impact of the Gulf of Suez if compared with the Gulf of Aqaba to the east. Moreover, the developed model indicates the cooling mechanisms near some islands in the north (i.e., Hurghada) while local heating mechanisms are described in the southern Regions (i.e., Farasan). The developed model could be extended to check the potential impacts of flash floods and the planned dams on the coastal regions in the framework of the current Mega development projects there. Moreover, it could be utilized to examine the climate change impacts on the physics of the marine ecosystems in the Red Sea. Finally, the suggested framework could Provide relative hazard, exposure, vulnerability, and risk maps of the Red Sea region that allow researchers and policymakers to identify coastal areas most at risk from local and global stressors.