Seascape architecture – incorporating ecological considerations in design of coastal and marine infrastructure

Abstract With nearly 60% of the human population concentrated around the coastlines, alongside growing threats from sea level rise and increased storminess, accelerated coastal development is inevitable. As most marine flora and fauna reside in coastal areas, anthropogenic changes to coastlines are a key reason for loss of coastal habitats, and associated ecosystem services. While coastal infrastructure such as seawalls or breakwaters add significant amounts of hard substrate for marine organisms, they do not support similar species assemblages to those of natural habitats. This is mainly due to design features related to steep slopes, low structural complexity, and high homogeneity, all of which are rarely found in natural habitats. This study provides an example for seascape architecture of coastal structures using ecologically sensitive designs and concrete technologies that enhance the structures’ biological and ecological value while contributing to structural integrity. Four 1.5 mx0.8 m seawall panels made of bio-enhancing concrete with high structural complexity were deployed in an active marina (Herzliya, Israel). The panels, spanned from the Mean High Higher Water (MHHW) down to the sublittoral zone, were surveyed 2, 7, 12, 18 and 22 months post deployment using 0.3 × 0.3 m quadrats in both intertidal and sublittoral zones of each panel. Bio-enhanced panels were compared to fixed control quadrats comprised of scraped sections of the original concrete marina seawall. Results demonstrated the effectiveness of applying ecological considerations for biological and ecological enhancement of active infrastructure. All community parameters examined (live cover, richness, biodiversity) were significantly higher on bio-enhanced panels compared to controls. Moreover, mobile invertebrates and resident fish species were clearly enhanced through design aspects (holes and crevices) of the bio-enhanced panels. The study provides an example of an emerging approach of assimilating ecological considerations into the design and construction of working waterfronts and active coastal infrastructure, thus reducing their ecological footprint without compromising their operational performance.