The influence of seagrass donor source on small‐scale transplant resilience

Concern for conservation of seagrass habitat has prompted international transplantation‐style restoration efforts. A recent review of these restoration efforts has highlighted the low success associated with small‐scale restorations, yet scaling up transplantation effort may be too costly for underfunded regions. Small‐scale transplant survival can be enhanced with alleviation of two underlying issues: restoration site selection and donor site selection. To investigate appropriate donor source selection, donor site environmental influence on seagrass (Halodule wrightii) transplant survival was examined by transplanting donor cores from two environmentally disparate sites to a transplantation site with limited environmental uncertainties. Donor sites were chosen to represent either end of a benthic light gradient (high versus low) to elucidate seagrass resilience to transplantation stress, with respect to donor site conditions. After total loss of the first trial, a second trial was conducted with stabilizing mesh placed over transplants to reduce stingray bioturbation. The second trial resulted in 100% survival of high light transplants after 12 months and moderate survival (30–60%) of low light transplants for the first six months. At 18 months, the second trial ended after sediment burial from a hurricane. One year post‐burial, a patch of H. wrightii recovered at the high light transplant site; after six years the patch expanded to approximately 74 m2, an area 37‐fold larger than originally planted. Results from this transplant experiment provide evidence that donor environment plays a role in transplant resilience. The transplants sourced from high light had 47% greater leaf area per shoot, were more resistant to transplantation stress, and recovered following an extreme event relative to low light transplants. Therefore, selection of donor plants with more resilience features, a transplantation site with limited environmental uncertainties, and adaptive intervention can enhance seagrass resilience at a small planting scale.