Greening of grey infrastructure should not be used as a Trojan horse to facilitate coastal development

Abstract

Climate change and coastal urbanization are driving the replacement of natural habitats with artificial structures and reclaimed land globally. These novel habitats are often poor surrogates for natural habitats. The application of integrated greening of grey infrastructure (IGGI) to artificial shorelines demonstrates how multifunctional structures can provide biodiversity benefits whilst simultaneously serving their primary engineering function. IGGI is being embraced globally, despite many knowledge gaps and limitations. It is a management tool to compensate anthropogenic impacts as part of the Mitigation Hierarchy. There is considerable scope for misuse and ‘greenwashing’ however, by making new developments appear more acceptable, thus facilitating the regulatory process. We encourage researchers to exercise caution when reporting on small‐scale experimental trials. We advocate that greater attention is paid to when experiments ‘fail’ or yield unintended outcomes. We advise revisiting, repeating and expanding on experiments to test responses over broader spatio‐temporal scales to improve the evidence base. Synthesis and applications. Where societal and economic demand makes development inevitable, particular attention should be paid to avoiding, minimizing and rehabilitating environmental impacts. Integrated greening of grey infrastructure (IGGI) should be implemented as partial compensation for environmental damage. Mutual benefits for both humans and nature can be achieved when IGGI is implemented retrospectively in previously developed or degraded environments. We caution, however, that any promise of net biodiversity gain from new developments should be scrutinized and any local ecological benefits set in the context of the wider environmental impacts. A ‘greened’ development will always impinge on natural systems, a reality that is much less recognized in the sea than on land.

A global analysis of complexity–biodiversity relationships on marine artificial structures

“…Ecoengineering complexity and missing microhabitats on these artificial structures to enhance the biodiversity and ecosystem functioning of their communities, is increasingly common. However, scientific studies providing the evidence base for this rapidly growing field are often poorly replicated and carried out over small spatial and temporal scales (Chapman et al, 2018;Firth et al, 2020). Global integration of small-scale ecological experiments such as those conducted here can be useful in identifying appropriate eco-engineering approaches before they are scaled up.…”

Little evidence that lowering the pH of concrete supports greater biodiversity on tropical and temperate seawalls

“…With contrasting effects of pH on different taxa (Guilbeau et al 2003), regions with different benthic community assemblages could also be influenced to varying degrees. One of the major criticisms of ecological engineering is that examples are often limited in their scope, and a recent review by Firth et al (2020) suggested revisiting, repeating, and expanding on experiments to test responses over broader spatio-temporal scales to improve the evidence base (Evans et al 2019).…”

Biogeomorphology, quo vadis? On processes, time, and space in biogeomorphology

“…The attractiveness of NbS comes from their potential to protect society from climate change impacts while slowing further warming, supporting biodiversity, and securing ecosystem services. Yet, many NbS have not rigorously been assessed in terms of reliability, cost‐effectiveness, and resilience to climate change (Lane, 2017; Firth et al ., 2020). It is important to understand the value and limitations of NbS for proper use (e.g.…”

“…It is important to understand the value and limitations of NbS for proper use (e.g. Firth et al ., 2020; Seddon et al ., 2020).…”

“…Monitoring of NbS can greatly improve our understanding of biogeomorphic feedback systems across a variety of scales and for a range of environments, adding to the scientific knowledge base. Many monitoring campaigns focus on a limited number of parameters but to better understand and evaluate biogeomorphic feedback systems, programmatic, richer, and smarter (matched in space and time) monitoring design is required (Weber et al ., 2018; Firth et al ., 2020; Johnson et al ., 2020; Seddon et al ., 2020; Viles, 2020). By including these requirements in the NbS project proposal, evaluation of the effectiveness of the NbS will be better informed and, importantly, in doing so lessons may be learned on biogeomorphic feedback systems facilitating the NbS.…”