Global review of eco-engineering research with recommendations for nature positive outcomes in coastal ecosystems

Coastal urbanisation and climate change pressures have intensified interest in eco-engineering solutions to enhance biodiversity and support sustainable coastal development. This study presents a systematic review of applied eco-engineering research conducted exclusively in urbanised seascapes, following PRISMA guidelines. Literature searches in Scopus, Web of Science, and ProQuest (January 1980 – June 2024) identified 6698 records, of which 128 studies met inclusion criteria. These represented 160 interventions across 26 countries spanning tropical, subtropical, and temperate zones. Interventions were categorised by design type, infrastructure, application phase (retrofit or construction), and target assemblage to evaluate ecological performance relative to unmodified controls. Results show that 143 interventions (89 %) increased species abundance or richness, whereas 17 (11 %) produced neutral or negative effects. Textured panels were most frequently applied (37 %), followed by transplantation (20 %), artificial rockpools (9 %), and pits and grooves (9 %). Simple, low-cost microhabitat additions consistently delivered positive outcomes across climate zones. Yet few studies co-reported asset-relevant engineering metrics along with the ecological part. Persistent research gaps include the absence of baseline data, long-term monitoring, cost-effectiveness assessment, and invasive-species evaluation, together with limited evidence from tropical regions. Findings demonstrate that eco-engineering provides an effective and scalable pathway to improve ecological performance of coastal infrastructure when designs are context-specific, structurally sound, and integrated into planning and retrofitting. Linking biodiversity responses with basic performance and cost information will help translate these ecological successes into widely adoptable, nature-positive coastal development. • 89 % of 160 field interventions improved biodiversity. • Microhabitat retrofits yield reliable gains across climates. • Evidence is uneven: tropics and key NbS types remain under-tested. • Baselines, >12-month monitoring, and invasive-species checks are rare. • Co-report engineering metrics and costs to support adoption.