Combining co-introduction with patch-size optimization as a novel strategy to maximize seagrass restoration

Area of Science:

• Marine ecology
• Restoration ecology
• Seagrass ecosystems

Background:

• Coastal ecosystem engineers (e.g., seagrasses) improve conditions for themselves and other species when at sufficient population density.
• Anthropogenic impacts have degraded coastal ecosystems, necessitating effective restoration strategies.
• Positive interactions (intraspecific and interspecific facilitation) are crucial for ecosystem health but underexplored in large-scale restoration.

Purpose of the Study:

• To evaluate if simultaneous restoration of intraspecific and interspecific facilitation enhances seagrass (Zostera marina) restoration yields.
• To test the efficacy of manipulating seagrass patch size and introducing herbivorous snails (Littorina littorea) in restoration.

Main Methods:

• A full factorial experiment manipulated seagrass patch size (intraspecific facilitation) and introduced snails (interspecific facilitation).
• Restoration yields were assessed under varying hydrodynamic exposure conditions.
• The study was conducted at a restoration scale.

Main Results:

• Intraspecific facilitation effects varied with site conditions: large patches increased yield by 40% in exposed areas but decreased it by 60% in sheltered areas.
• Interspecific facilitation (snail introduction) increased seagrass yields by an average of 73%.
• Plots with surviving snails showed up to 20 times more seagrass shoots than those without.

Conclusions:

• Co-introducing epiphyte grazers is a successful large-scale restoration strategy for seagrasses.
• Integrating both inter- and intraspecific facilitation into restoration designs can significantly improve success rates.
• These strategies should be tailored to specific environmental stressors, as they may be detrimental in their absence.