Temperature and irradiance variability on the Egyptian coast of the Red Sea during the 2020 bleaching event

Dosoky, Muhammad Yusuf Abdoh; Hanafy, Mahmoud Hassan; Ahmed, Mohamed Ismail; Madkour, Fedekar Fadel

doi:10.21608/ajbas.2022.128337.1096

Temperature and irradiance variability on the Egyptian coast of the Red Sea during the 2020 bleaching event

Document Type : Original Article

Authors

¹ Department of Marine Science, Faculty of Science, Port Said University, Port Said

² Department of Marine Science, Faculty of Science, Suez Canal University, Ismailia

³ Marine Science Department, Faculty of Science, Port Said University

10.21608/ajbas.2022.128337.1096

Abstract

Heat and irradiance stressors are critical factors affecting coral reefs, especially during the summer season. In the present study, daily sea surface temperature (SST), degree heating weeks (DHWs), and photosynthetically active radiation (PAR) remotely collected by NOAA CRW were assessed in three geographical sectors during the summer of 2020. The results indicated that SST had increased along a latitudinal thermal gradient from the north to the south. On the other hand, the overall accumulated heat stress above the usual maximum climatological SST did not decrease below 4°C-weeks in the three studied sectors and most of the heat stress was concentrated in the north. Associating with the pattern of the SST, the mean PAR levels had also increased from the north to the south by only one Einstein m-2 day-1. In the light of the present study, increases in the SST and PAR levels that have coincident with the 2020 bleaching pattern recorded at the Egyptian coast may synergistically threaten coral reefs at the southern coast. Moreover, although the accumulated heat stress exceeded the bleaching threshold (>4°C-weeks), it may still less severe to corals inhabiting the northern reefs.

Keywords