The Impact of Increasing Seawater Temperatures over the Last 30 Years on the Reproductive Cycle of the Pearl Oyster Pinctada radiata (Leach, 1814) in the Arabian Gulf

Abstract

The pearl oyster Pinctada radiata (Leach, 1814), a crucial ecosystem builder in the Arabian Gulf, has experienced a significant decline, mainly attributed to anthropogenic pressures. This study aimed to characterize the reproductive cycle of P. radiata in Qatar and compare the current data with historical records in the region obtained between 1992 and 1993. From May 2020 to April 2022, we found a well-defined seasonal reproductive pattern, with a narrow peak spawning period in April. This observation stands out strongly from the previous recordings of 1992–1993 for the region, where spawning extended from May to August. The observed shift in the reproductive cycle coincides with a notable increase in the maximum sea surface temperature (SST), rising from 34 °C in August (1992–1993) to 37 °C in July (2020–2022), while the minimum SST remained stable at 15–16 °C in January during both periods. Furthermore, a contraction in the duration of the main spawning period was observed, with spawning now confined to an earlier and shorter timeframe. We propose that climate change, in addition to other environmental stressors, must have played a key role in modifying the reproductive cycle of the pearl oyster P. radiata in the Arabian Gulf. These findings highlight the importance of further monitoring reproductive dynamics in the context of climate change.