Restoration of threatened red gorgonian populations: An experimental and modelling approach

• Published in: Biological conservation 2008-02, Vol.141 (2), p.427-437
• Main Authors: Linares, Cristina, Coma, Rafel, Zabala, Mikel
• Format: Article
• Language: English
• Subjects: Algae; Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; Cnidaria; Conservation; conservation areas; Conservation, protection and management of environment and wildlife; cost effectiveness; ecological restoration; Environmental degradation: ecosystems survey and restoration; environmental models; Fundamental and applied biological sciences. Psychology; Gorgonacea; light; Marine; marine environment; Marine protected areas; Matrix models; mortality; Octocorals; Paramuricea clavata; Parks, reserves, wildlife conservation. Endangered species: population survey and restocking; Restoration; threatened species; Transplants
• ISSN: 0006-3207; 1873-2917
• DOI: 10.1016/j.biocon.2007.10.012

The increasing disturbances affecting marine communities highlight the need to examine restoration measures that can be added to other conservation efforts for threatened populations. The main goal of this study was to examine the usefulness of ecological restoration in the management of gorgonian populations damaged by diving activity in intensively visited marine protected areas (MPAs). We used field experiments as well as simulations from size-structured matrices to assess the utility of transplantation of living fragments from damaged colonies to increase the viability of threatened populations. Despite results showing that technique failure caused the loss of 40% of transplants, well-attached transplants achieved survival rates (80%) similar to those of natural colonies. Surprisingly, environmental conditions (light level and presence of algae) did not have a significant effect on the mortality of the transplants, but did affect methodological failure rates (37% of transplants were lost in the photophilous treatments in contrast to the 25% lost in sciaphilous treatment). The simulations showed a substantial increase in the annual population growth rate ( λ) only when transplantation was performed every two years and under the most demanding conditions (recovering 75% of the detached colonies and obtaining 3 fragments from each one). Predictions from the size-structured matrix model suggest severe limitations of this technique at larger spatial scales. However, our study confirms the feasibility of this restoration measure to contribute to the recovery of populations in MPAs affected by local disturbances. The experimental and modelling approaches developed here may provide useful guidelines for future studies on the restoration of marine populations.