Comprehensive Associations Between Pearl Oyster Beds with Corals, Seagrass Beds and Algal Beds Recorded in the Hottest Sea on the Planet

Reem AlMealla^1*Brisneve Edullantes²Mohamed Ali¹Zainab Mardhi¹Manaal Khan¹Mominah Sharif¹Ayesha Tyabji¹Nada AlMoussa¹Fatima Omran³Mariam Hasan³Layla Hazeem³Ahmed Khamis⁴Ebrahim Al Khalifa⁵Theresa Dabruzzi⁶

• ¹Nuwat for Environmental Research & Education, Al-Janabiyah, Bahrain
• ²University of the Philippines Cebu College of Science, Cebu City, Philippines
• ³University of Bahrain, Sakhir, Bahrain
• ⁴Supreme Council for Environment, Manama, Bahrain
• ⁵Arab Regional Center for World Heritage, Manama, Bahrain
• ⁶Saint Anselm College Department of Biological Sciences, Manchester, United States

Pearl oyster ecosystems have played a key role in Bahrain's marine economy and cultural heritage for centuries. Despite their ecological importance, systematic research on Bahrain's pearl oyster beds is lacking since the late 1980s. In this study a detailed assessment of the benthic composition, pearl oyster community structure, population size, and pearl yield on pearl oyster beds is provided for Bahraini waters. Field surveys were conducted between January and May 2024 at ten sites across Bahrain's Northern, eastern, and western waters. A total of 1,973 pearl oysters were collected, representing nine species, with Pinctada radiata dominating across all sites. Pinctada species richness was highest in the north (six species) with greater oyster densities (34 ± 4.9 oysters/m²) compared to the east (6 ± 2.7 oysters/m²) and west (10 ± 2.9 oysters/m²). Oyster beds were associated with coral in the north (up to 22.6 ± 2.3% cover), algae in the upper eastern (75.6% ± 4.4%) and western (65.8% ± 4.2%) sites, and seagrass mixed with algae in the lower eastern (27.9% ± 4.9% seagrass) and western (33.1% ± 4.2% seagrass) sites. Pearl yield was highest in the Northern and western sites, with Hayr Bu Amamah (14.3%) and Hayr Bul Thamah (11.1%) showing the highest incidence of pearls. Given that these oyster beds inhabit some of the most extreme marine environments on the planet, where temperatures fluctuate annually between 16°C to 36°C and salinity exceed 50 ppt in certain areas. These findings provide critical baseline data to inform sustainable management, conservation planning and marine heritage protection in Bahrain and the wider Gulf region.