Coral Reef Long-Term Monitoring at East and West Flower Garden Banks: 2025 Annual Report

This report summarizes fish and benthic community observations and water quality data collected from the coral reefs of East Flower Garden Bank (EFGB) and West Flower Garden Bank (WFGB) in 2025, alongside 36 years of historical long-term monitoring data. EFGB and WFGB are part of the National Oceanic and Atmospheric Administration’s Flower Garden Banks National Marine Sanctuary (FGBNMS), located in the northwestern Gulf of America. The annual coral reef long-term monitoring program, initiated in 1989, is funded by FGBNMS and the Bureau of Ocean Energy Management, with support from the National Marine Sanctuary Foundation. In 2025, mean coral cover, estimated from random transect data within EFGB and WFGB one-hectare study sites, was 55%. Coral cover at WFGB has increased significantly over time, while EFGB values have remained stable. The Orbicella spp. complex, listed as threatened under the Endangered Species Act, accounted for the majority of the coral cover within the study sites. Benthic composition across the coral reef differed significantly between the banks, largely due to differences in macroalgae and colonizable substrate cover. While mean macroalgae cover was 33% within the EFGB study site and 13% within the WFGB study site, macroalgae cover has increased significantly at both banks since 1998. The reef fish community remained characterized by low diversity and high biomass. Trophic structure differed between banks in 2025, with piscivores comprising the greatest biomass at EFGB, while WFGB shifted to a planktivore-dominated community driven by high abundances of Atlantic creolefish. Regal demoiselles, which were not observed in 2024, were detected in low numbers in 2025, suggesting recent recruitment. A significant increase in reef-cap seawater temperature was detected at both banks from 1990 to 2025. In situ reef-depth temperature data indicated that EFGB exceeded site-specific bleaching thresholds in 2025, whereas WFGB did not meet threshold conditions associated with widespread bleaching. Coral bleaching and paling remained low in 2025, with evidence of recovery following consecutive bleaching years in 2023 and 2024, although disease persisted as a secondary stressor. The Flower Garden Banks remains one of very few reefs in the Western Atlantic Ocean where coral reefs appear to have resisted degradation over the last several decades. Continued long-term monitoring will be essential for understanding the mechanisms underlying this apparent resistance and for supporting effective sanctuary management.

Key Words

benthic community, coral ecosystem, coral reef, fish community, long-term monitoring, Flower Garden Banks National Marine Sanctuary, Gulf of America, marine protected area, water quality, coral disease, coral bleaching