Structural design influences biological community composition on a North Carolina jetty

Marine urbanization creates novel benthic habitat in coastal areas around the world. This process includes the construction of artificial reefs, energy infrastructure, and jetties. These hard structures are colonized by epibenthic communities of macroalgae and sessile invertebrates. The factors influencing the composition of epibenthic communities must be understood to build structures that incorporate epibenthic organisms into their design through anthropogenic ecosystem engineering. An epibenthic community on the Masonboro Inlet jetty at Wrightsville Beach in coastal North Carolina, USA was surveyed biweekly from May to September 2022. Both sides of the jetty (aspect), at two depths (1.0 m; 5.0 m below MLLW) were surveyed providing four sites (north-shallow, south-shallow, north‐deep, south‐deep). The orientation of each surface photographed was recorded. Physical drivers of community structure (aspect, depth, and orientation) were compared to environmental drivers (light and temperature) recorded every 15 minutes for the duration of the sampling period. Overall, the effect of depth on community composition was greater than the effect of orientation, which was greater than the effect of aspect. Community appeared to better correlate with light than with temperature, though after accounting for structural effects and sample date, additional effects of light and temperature were minimal. Algal abundance was greater at shallow sites and on horizontal surfaces while invertebrate abundance was greater at deep sites and on vertical surfaces. We propose that these patterns and drivers of community composition observed have functional implications at the ecosystem level which may be considered during planning and design of new marine structures.