Seagrass composition shifts and declines associated with reduced light, high phosphate, and elevated water temperatures in Turneffe Atoll Marine Reserve, Belize

A significant shift and decline in seagrass species composition at Turneffe Atoll Marine Reserve, Belize, has been documented between 2022 and 2025. Thalassia testudinum, a dominant seagrass species, showed steady declines while Syringodium filiforme became more prevalent. By 2025, shallow transects had lost all seagrass cover, attributed to reduced light availability, elevated phosphate concentrations, and water temperatures exceeding the thermal optimum for these species. This decline, observed even within a protected marine reserve, highlights the vulnerability of seagrass meadows to environmental stressors, with broader implications for the resilience of adjacent coral reef systems in the Mesoamerican Barrier Reef System. The study used SeagrassNet global monitoring protocols to assess environmental and biological indicators, providing critical insights into the ecological impacts of shifting conditions on these foundational coastal ecosystems.

Fietz, K. A., Scavo Lord, K., & Novak, A. B. (2026). Seagrass composition shifts and declines associated with reduced light, high phosphate, and elevated water temperatures in Turneffe Atoll Marine Reserve, Belize. Frontiers in Marine Science, 13. https://doi.org/10.3389/fmars.2026.1842116