Lessons learned from an experimental restoration trial of habitat-forming macroalgae under intense herbivore pressure

Documenting operational setbacks is essential for refining marine conservation strategies. We present the lessons learned from an experimental restoration trial of habitat-forming Cystoseira sensu lato species under intense grazing pressure in Gökova Bay, eastern Mediterannean Sea. Transplanted thalli placed inside protective PVC-and-metal mesh exclusion-cages exhibited rapid growth and recruitment. However, upon cage removal, invasive Siganus spp. entirely consumed the macroalgae within 48 h. Operational constraints included wave-induced cage deformation, mesh clogging, and temperature-driven donor mortality (ΔT = 3 °C). These practical reflections demonstrate that direct transplantation is ecologically unviable without prior mitigation of widespread biotic stressors.