Positive Ecological Interactions and the Success of Seagrass Restoration

Abstract

Seagrasses provide multiple ecosystem services including nursery habitat, improved water quality, coastal protection, and carbon sequestration. However, seagrasses are in crisis as global coverage is declining at an accelerating rate. With increased focus on ecological restoration as a conservation strategy, methods that enhance restoration success need to be explored. Decades of work in coastal plant ecosystems, including seagrasses, has shown that positive species relationships and feedbacks are critical for ecosystem stability, expansion, and recovery from disturbance. We reviewed the restoration literature on seagrasses and found few studies have tested for the beneficial effects of including positive species interactions in seagrass restoration designs. Here we review the full suite of positive species interactions that have been documented in seagrass ecosystems, where they occur, and how they might be integrated into seagrass restoration. The few studies in marine plant communities that have explicitly incorporated positive species interactions and feedbacks have found an increase in plant growth with little additional resource investment. As oceans continue to change and stressors become more prevalent, harnessing positive interactions between species through innovative approaches will likely become key to successful seagrass restoration.

Mimicry of emergent traits amplifies coastal restoration success

“…Here, we show that by deploying transplants inside establishment structures, our salt marsh transplant size was nine times smaller compared to the earlier applied clumped transplant design 16 , greatly reducing the need for donor material and avoiding potential damage to donor sites or demands on nurseries to cultivate transplants. As clumping has also been previously found to benefit seagrass transplants 51 , and a review and separate global analysis showed that small-scale facilitations and large-scale approaches will generally benefit seagrass restoration success 17,52 , our finding suggests that the use of establishment structures may be more beneficial for seagrass restoration.…”

“…3D-printing may, for example, prove a very useful tool to develop biodegradable prototypes as it opens up virtually infinite design possibilities and allows for fine details at the microscale 56,57 . To enable such optimization, identifying the bottlenecks that hamper establishment of the target species should be the first step 19,52,58 . Next, it should be established whether the target species, or species that mutualistically interact with the target species 59 , possesses emergent traits that mitigate these bottlenecks, after which the establishment structure's design can be improved to more accurately simulate these traits.…”

“…Furthermore, restoration of shellfish and coral reefs has been found to be hampered by a lack of suitable settlement substrate, often combined with high predation pressure on recruits due to a lack of habitat complexity 42,70 . In such cases, structures that mimic attachment substrate provisioning and predation reduction benefits typically generated by established reefs (e.g., in texture and crevice size or scaring prey with predator cues) may be helpful 19,42,52,70,71 . Hence, we suggest that our trait-based approach may inspire follow-up research investigating how mimicry of emergent traits by habitat-forming species may enhance establishment and restoration yields in harsh environments.…”

Using Propagules to Restore Coastal Marine Ecosystems

“…Once settled, survival of individuals to a stage when they in turn can reproduce depends on the presence of conditions necessary for growth, such as food or light, and the absence of negative influences that cause mortality, such as predators, competitors, or physiological stressors (e.g., Doropoulos et al, 2016). Survival and growth can also sometimes be enhanced by the presence of conspecifics, or by symbiotic or mutualistic interactions (Valdez et al, 2020).…”

Facilitating Better Outcomes: How Positive Species Interactions Can Improve Oyster Reef Restoration

“…However, the foundational paradigm in coastal and marine restoration has been that competition limits an organism's regrowth. Accordingly, restoration projects have focused on minimizing negative interactions, while largely ignoring potential positive ones (Silliman et al, 2015;Renzi et al, 2019;Valdez et al, 2020). However, this "foundational" principle stating that negative interactions are paramount in restoration came directly from forestry science without first testing it in marine systems (Halpern et al, 2007).…”