[A-HW22] Material transportation and cycling at the land-sea interface: from headwaters to the ocean

[AHW22-04] Increasing phosphate load inhibits skeletal formation in coral juvenile polyps

*Mariko Iijima¹, Ko Yasumoto², Jun Yasumoto³, Akira Iguchi¹, Mina Hirose⁴, Atsushi Suzuki¹, Shugo Watabe² (1.National Institute of Advanced Industrial Science and Technology, 2.School of Marine Biosciences, Kitasato University, 3.Faculty of Agriculture, University of the Ryukyus, 4.Tropical Technology Plus)

Keywords:Phosphate load, Coral, Adsorbed phosphorus

The decline of coral reefs has become a serious global concern, with widespread coral bleaching being observed. The reduced recovery capacity of corals is highlighted, particularly attributing to the deterioration caused by excessive nutrient runoff, especially from agricultural discharges. This contributes to coral degradation, impacts biodiversity, increases water turbidity, and promotes bacterial growth, leading to coral diseases. While the impact of nitrogen is well-studied, the influence of phosphorus, often overlooked due to its low concentration in seawater, remains unclear.
This study investigates the long-term effects of phosphates on coral larvae, revealing that even at low concentrations, phosphates hinder skeletal formation. The experimental system demonstrates that increasing the volume of rearing seawater elevates the total phosphate concentration, emphasizing the importance of evaluating both concentration and total amount. The research underscores the potential detrimental effects of phosphates on coral growth, calling for a reevaluation of the impact of phosphates on coral reefs and providing significant implications for conservation efforts. Considering the significant influx of phosphorus into marine environments, the study proposes specific terrestrial measures to support sustainable coral reef conservation.