The current global coral crisis has pushed forward the development of a wide range of strategies to improve coral resilience to withstand the pressing anthropogenic impacts (Voolstra et al., 2021). Some of these interventions rely on successfully collecting gametes to sexually propagate corals. Therefore, detailed information on coral spawning is crucial to advance basic and applied research and inform strategies for coral reef conservation and restoration. Currently, reproduction data is available for over 300 scleractinian species in 61 genera in the Indo-Pacific (Harrison, 2011; Baird et al., 2021), where over 600 hard coral species are reported (Veron et al., 2015). In the Red Sea, where research on coral reproduction historically started in the Gulf of Aqaba (Rinkevich and Loya, 1979; Shlesinger and Loya, 1985; Shlesinger et al., 1998; Rapuano et al., 2017), synchronous spawning of scleractinian corals at central latitudes has been observed around full moon nights in spring (Bouwmeester et al., 2015; Osman et al., 2024). In the Indo-Pacific region, most spawning observations are on species of the genus Acropora, with 38% of the total spawning records, while information on other coral genera is relatively scarce (Baird et al., 2021).

Pavona Lamarck, 1801, is commonly observed in shallow Indo-Pacific coral reefs, including the Red Sea (Terraneo et al., 2017), but few studies have described its reproductive biology. Species of Pavona are almost exclusively gonochoric and broadcast spawners (Shlesinger et al., 1998; Harrison, 2011). In situ spawning has been reported two and three days after the full moon of November in Pavona cactus Forskål, 1775, in the Great Barrier Reef (Marshall and Stephenson, 1933), of March in Pavona gigantea Verrill, 1869, in the Galapagos Islands, Ecuador (Glynn et al., 1996), from January to April for Pavona varians Verrill, 1864, and Pavona sp. (later formally described as Pavona chiriquiensis Glynn, Maté & Stemann, 2001) in the Gulf of Chiriquí, Panama (Glynn et al., 2000), and in October for Pavona clavus Dana, 1846, in Contadora Island, Panama (Glynn et al., 2011). In situ spawning was observed six days after full moon of August in Pavona decussata Dana, 1846, in Kochi Prefecture, Japan (Mezaki et al., 2014). In the Red Sea, no in situ spawning observations have been reported so far for Pavona; however, April has been inferred as the spawning month in P. varians, based on the oocyte maturity (Bouwmeester et al., 2015). Here, we report the first in situ spawning observation of Pavona maldivensis Gardiner, 1905.

In April and May 2024, in situ surveys to document coral spawning were conducted in Al Fahal Reef (22°18’21” N; 38°57’44” E), a midshore reef located in the central Red Sea (Garcias-Bonet et al., 2024). Underwater surveys took place by SCUBA divers during two consecutive months on 21–25 April 2024 and 20–24 May 2024, covering the full moon nights on 24 April and 23 May 2024. Surveys were conducted from 17:30 to 19:00 and from 21:30 to 23:00 at depths from 8–10 meters using red light torches to minimize the negative impact of light on coral spawning. Spawning observations and timing were noted and pictures and videos were taken with an Olympus TG-6 camera equipped with an Olympus PT-059 underwater housing (OM System). In situ seawater temperature was monitored using a Multiparameter CTD probe (Ocean Seven 310, Idronaut) as part of a sustained environmental data observation platform (Garcias-Bonet et al., 2024).

We report and document the first in situ spawning observation of Pavona maldivensis Gardiner, 1905 ( Figure 1 ) in the central Red Sea (Al Fahal Reef) on the full moon night, on 23 May 2024 at 18:49h, ten minutes before sunset time (18:59h), when in situ daily mean seawater temperature was 29.68°C. A medium size P. maldivensis colony (80 cm in diameter) at a depth of 9 m was observed releasing sperm in a dense cloud surrounding the entire colony for seven minutes ( Figure 1 , Supplementary Movie 1 ). No eggs seemed to be released from the colony, suggesting that P. maldivensis is likely gonochoric, in agreement with reproductive data available for other Pavona species. For instance, Pavona varians has been reported as gonochoric in the Red Sea (Bouwmeester et al., 2015; Shlesinger et al., 1998) and mostly gonochoric with some hermaphrodite colonies in Eastern Pacific (Glynn et al., 2000).

Contrary to the spawning synchrony observed in many scleractinian corals (Baird et al., 2009, 2021), spawning times in Pavona genus doesn’t seem to be synchronized, with in situ observations ranging from midday to few hours before sunrise around full moon nights across different months. Similarly to our spawning observation at sunset time in P. maldivensis, Pavona sp. spawning was reported shortly after sunset in Panamá (Glynn et al., 2000), P. gigantea spawning was reported in the late afternoon (two hours before sunset) in Galapagos Islands, Ecuador (Glynn et al., 1996), and the release of eggs in Pavona explanulata was observed three hours after sunset in Taiwan (Lin and Nozawa, 2017). Contrary, Pavona sp. spawning was reported at midday in Thailand (Plathong et al., 2006), male and female colonies of P. varians were observed spawning two hours before sunrise in Panamá (Glynn et al., 2000) and P. decussata was observed spawning about one hour before sunrise in Japan (Mezaki et al., 2014).

The spawning observation of P. maldivensis reported here is based on a single male colony; therefore, further research, increasing the observation time window and number of monitored colonies, is needed to fully describe the spawning patterns, characterize the reproductive biology and confirm the gonochorism of P. maldivensis in the Red Sea. P. maldivensis is known to be widespread from the Red Sea to the East Pacific Region (Sheppard, 1991; Veron, 2000; Salvat et al., 2016). In the Red Sea, it can be commonly observed from very shallow to upper mesophotic low-light environments such as under reef crest ledges and underhangs (Al Tawaha et al., 2019), with Pavona genus accounting on average for less than 1% of the benthic cover in the central Red Sea (Monroe et al., 2018). This first report on the in situ spawning timing for P. maldivensis in the Red Sea contributes to expanding global coral spawning databases and provides valuable data on its reproductive biology, which is relevant for coral restoration and conservation efforts.