Negative effects by mineral accretion technique on the heat resilience, growth and recruitment of corals

• Published in: PloS one Vol. 19; no. 12; p. e0315475
• Main Authors: Knoester, Ewout Geerten, Sanders, Richard, Durden, Daisy, Masiga, Bulisa O., Murk, Albertinka J., Osinga, Ronald
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 30.12.2024; Public Library of Science (PLoS)
• Subjects: Animals; Anthozoa - growth & development; Anthozoa - physiology; Artificial reefs; Biology and Life Sciences; Calcium; Calcium carbonate; Calcium Carbonate - metabolism; Calcium channels (voltage-gated); Carbonates; Chemical properties; Climate adaptation; Climate change; Coral Bleaching; Coral growth; Coral Reefs; Coral reefs and islands; Corals; Corrosion; Cost analysis; Earth Sciences; Electric properties; Electrolysis; Engineering and Technology; Environmental aspects; Growth; Heat waves; Hot Temperature; Influence; Kenya; Medicine and Health Sciences; Methods; Minerals - metabolism; Physical Sciences; Population decline; Precipitation; Rehabilitation; Resilience; Sea-water; Seawater; Species; Thermal properties; Kenya
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0315475

Restoration and artificial reefs can assist the recovery of degraded reefs but are limited in scalability and climate resilience. The Mineral Accretion Technique (MAT) subjects metal artificial reefs to a low-voltage electrical current, thereby creating a calcium-carbonate coating. It has been suggested that corals on MAT structures experience enhanced health and growth. However, prior studies report conflicting results potentially due to different conditions, species and approaches used. We investigated how MAT influences the bleaching resilience, condition and growth of four coral species and natural coral recruitment in Kenya. Coral fragments were outplanted on charged iron tables using commonly-applied settings (6 V; 0.84 A m -2 ). After one month, when all tables had acquired a calcium-carbonate coating, half of the tables were taken off electricity to serve as controls. Both treatments (MAT and Control) were monitored on coral brightness, condition (live tissue cover), growth and natural recruitment for one year, during which a marine heatwave occurred. Coral bleaching was significantly more severe on MAT for all studied species. For three species, coral condition dropped sharply during the heatwave and this decline was faster and more severe on MAT. Coral growth was reduced during the heatwave for all corals and remained low for one species on MAT. After one year, the Control harboured 34 coral recruits, whereas none were found on MAT. Thus, while MAT can be useful to prevent corrosion of metal artificial reefs, we do not recommend MAT as reported here to improve coral growth, condition, heat resilience or recruitment.