Coral restoration for coastal resilience: Integrating ecology, hydrodynamics, and engineering at multiple scales

Abstract

The loss of functional and accreting coral reefs reduces coastal protection and resilience for tropical coastlines. Coral restoration has potential for recovering healthy reefs that can mitigate risks from coastal hazards and increase sustainability. However, scaling up restoration to the large extent needed for coastal protection requires integrated application of principles from coastal engineering, hydrodynamics, and ecology across multiple spatial scales, as well as filling missing knowledge gaps across disciplines. This synthesis aims to identify how scientific understanding of multidisciplinary processes at interconnected scales can advance coral reef restoration. The work is placed within the context of a decision support framework to evaluate the design and effectiveness of coral restoration for coastal resilience. Successfully linking multidisciplinary science with restoration practice will ensure that future large‐scale coral reef restorations maximize protection for at‐risk coastal communities.

Evidence of Sexual Reproduction in Out-Planted Coral Colonies

“…Active intervention involves the implementation of different protocols such as the use of "fragments of opportunity" or micro-fragmentation, and, in both cases, coral fragments can be either grown in nurseries before they are re-attached to the bottom or they can be directly out-planted in restoration sites if there are suitable conditions to do so [7]. The design of such restoration strategies is defined by spatial, temporal, and cost scales [11]. An advantage when using fragments of opportunity is that these fragments detach from the coral colony by natural physical disturbances such as wave action, storms, and hurricanes, among others; therefore, this protocol avoids the fragmentation of "donor" colonies, which is the most common technique for obtaining more individuals [7] and no damage or stress is inflicted on the healthy adult colonies.…”

“…Besides long-term viability, active coral restoration protocols face a series of challenges, so the assistance with coral restoration, its feasibility, and its success remain controversial within the scientific community [7]. First, active coral restoration must be adapted and designed considering each site's local characteristics (oceanographic and socio-ecological), and there should be a trial of different protocols to determine the most suitable restoration technique [11]. Also, the design of all restoration programs must contemplate the biology and physiology of the targeted species since they respond differently to environmental and anthropogenic stress depending on their life history [9,10,12].…”

Coastal Restoration Challenges and Strategies for Small Island Developing States in the Face of Sea Level Rise and Climate Change

“…It serves as a critical tool for the restoration of declining coral species [231], the rehabilitation of degraded ecosystems [232], and the recovery of fish assemblages [233]. While it has not been widely tested for its impact on reducing wave energy and runup due to logistical and scale limitations, scaling up restoration efforts for coastal protection necessitates the integration of coastal engineering, hydrodynamics, and ecology across various spatial scales [234]. This approach should also encompass coastal zone management, climate change adaptation and mitigation, and the implementation of a comprehensive national coastal ecosystem restoration plan.…”

“…Restore natural and nature-based features to attenuate wave energy and runup [234]. These features encompass coral reefs, submerged or emergent vegetation (such as seagrasses, mangroves, and salt marshes), dune systems, and wetlands.…”

An evaluation tool for assessing coral restoration efforts

“…Most (65%) coral restoration monitoring studies focus on the performance of individual colonies (i.e., growth and survival) while an additional 35% of studies combine these indicators with only a limited number of other ecological factors such as recruitment, competition, and predation (Hein et al, 2017;Boström-Einarsson et al, 2020). Although growth and survival metrics are useful to assess individual colony performance, such metrics may be insufficient to fully characterize and assess the effectiveness of the methods used by restoration programs (Hein et al, 2017;Goergen et al, 2020;Viehman et al, 2023). As suggested in recent studies, published data are often biased towards only reporting high survival, and researchers, practitioners, and managers may avoid reporting failed restoration projects due to concerns about losing permits or funding and/or propagating a negative public perception of coral restoration (Bayraktarov et al, 2020;Boström-Einarsson et al, 2020).…”