Promoting self‐facilitating feedback processes in coastal ecosystem engineers to increase restoration success: Testing engineering measures

Abstract

1. Coastal ecosystem engineers often depend on self-facilitating feedbacks to ameliorate environmental stress. This makes the restoration of such coastal ecosystem engineers difficult. We question if we can increase transplantation success in highly dynamic coastal areas by engineering measures that promote the development of self-facilitating feedback processes. 2. Intertidal blue mussels Mytilus edulis are a typical example of ecosystem engineers that are difficult to restore. A lack of self-facilitating feedbacks at low densities limits establishment success when young mussels are transplanted on dynamic mudflats. 3. In a large field experiment, we investigated the possibility of increasing transplantation success by stimulating the formation of an aggregated spatial configuration in mussels, thereby reducing hydrologically induced dislodgment and the risks of predation. For this, we applied engineering measures in the form of fences that trapped wave dislodged mussels. 4. Mussel loss rates were significantly lower when mussels were placed between both artificial fences, and in high densities (4.2 kg/m 2) compared with mussels placed in areas without fences and in low densities (2.1 kg/m 2). The fences induced the formation of a banded pattern with high local mussel densities, which locally reduced predation. 5. Synthesis and applications. Our results underline the importance of actively promoting the development of self-facilitating processes, such as aggregation into patterns, in restoration projects of ecosystem engineers. In particular, the current study shows that engineering measures can help to initiate these kinds of selffacilitating interactions, especially in highly dynamic areas.

Incorporating facilitative interactions into small‐scale eelgrass restoration—challenges and opportunities

“…In Denmark, crab predation on mussels that were attached to BESEs led to very high mortality, so additional measures such as cages may be necessary in areas of high predator abundance, until the mussels are large, or abundant, enough to escape predation (Schotanus et al 2020a). In addition, as evidenced by the complete loss of mussels at one of the most exposed sites, BESEs alone cannot ensure the survival of translocated mussels in highly exposed areas, and additional nets or fences might be necessary (de Paoli et al 2015; Schotanus et al 2020b).…”

Operationalising positive tipping points towards global sustainability

“…We suggest the 'green revolution' would make an instructive historical case study where increasing population, food production, and proliferation of new technologies all fed back to amplify each other. So too would contemporary initiatives co-opting 'ecosystem engineers' and utilising technology to trigger positive tipping in ecosystems harvested for food -such as blue mussel beds (Schotanus et al, 2020).…”

Survival of the Systems

“…Forests of diverse tree species, by contrast, typically modify their microclimate in a manner that enhances tree growth [69]. Reintroducing ecosystem engineers and promoting such positive feedbacks can be key to successful ecosystem restoration [70].…”