From Grey to Green infrastructure: Assessing the Biodiversity on North America’s First Living Seawall Installation

Daniel Lopez^{1, 2}

¹University of Massachusetts, USA - ²Stone Living Lab, USA

Global development and hardening of shorelines has significantly reduced available habitat for marine organisms. This trend has led to decreased biodiversity in coastal urbanized areas. Urbanized marine environments provide simplistic homogeneous substrates lacking critical microhabitats for native fauna, and are more prone to biological invasions from non-native species.The Living Seawalls project, begun in Sydney, Australia, aims to ameliorate the effects of urbanization by deploying concrete panels that mimic vital features of microhabitats and are affixed to existing seawalls. Here we report on the first Living Seawalls installation in North America. In September 2024, Living Seawalls were installed at three locations in the Boston Harbor varying in sunlight exposure and flow conditions... To assess differences in biodiversity after installation, we sampled species richness and abundance via quadrat surveys and mobile species videos using a Before-After Control Impact Assessment design with paired controls as well as assessing the impact of different panel types at different tide heights. Additional control sites were also measured to assess site level diversity in comparison to the treatment. Our preliminary data details the low biodiversity on Boston seawalls, the first series of colonizing species on the panels, and diversity of species that occupy in the first nine months since deployment. We speculate on what these early results mean for long-term colonization and biodiversity of Living Seawalls in New England as well as the importance of environmental variation in our three installations.