Urban pocket beaches as nesting habitat for marine turtles: Their importance and risk from inundation

Sandy areas between rocky uplands, or natural pocket beaches, provide important habitat for coastal wildlife. On developed coasts, similar sandy areas, called urban pocket beaches, occur in the gaps between properties with coastal armoring (sea walls or revetments). These urban pocket beaches provide important nesting, foraging, and resting habitat for wildlife, particularly on extensively armored beaches. However, it is unclear if urban pocket beaches provide the same function as natural pocket beaches or offer benefits (e.g., reduced risk of inundation or erosion) lost at nearby armored areas. To address these knowledge gaps, we analyzed loggerhead marine turtle nesting patterns and reproductive success to determine if urban pocket beaches represent preferred nesting habitat along armored coastlines. We also determined if nests at urban pocket beaches are more likely than nearby armored and unarmored beaches to be inundated from wave runup, which could alter the incubation environment and nest productivity of marine turtles. The linear extent of urban pocket beaches in Florida was identified, then loggerhead marine turtle nesting success, nest density, and hatching success was compared between urban pocket beaches with armoring and beaches without armoring. We also modeled differences in wave runup exposure at these beaches under current conditions (2016–2019) without and with tropical storms and future (2060) intermediate-low and high sea level rise scenarios. Overall, pocket beaches account for less than 2% of Florida’s nesting beaches with higher abundance on more heavily armored shorelines. Nesting density in pocket beaches were similar to nearby beaches without armoring. However, female turtles were more likely to nest in urban pocket beaches compared to adjacent armored areas, and pocket beach nests had a higher hatchling success rate than unarmored and armored beaches. Our models suggest that exposure to wave runup varies by geographic location, but overall pocket beaches provided viable nesting habitat in all areas surveyed. Thus, managers should advocate for preserving urban pocket beaches on armored shorelines