Donna Marie Bilkovic

Ribbed mussels (Geukensia demissa) are secondary foundation species of salt marshes along the Atlantic East Coast, providing ecosystem services such as water filtration, nutrient removal, shoreline stabilization, and sediment accretion. Despite their integral role in ecological and structural marsh processes, it remains unclear whether living shorelines—now widely promoted as a nature-based coastal protection—provide comparable habitat for ribbed mussels as natural fringe marshes. In this study, we compare juvenile ribbed mussel settlement across four living shoreline and natural fringing marsh site pairs in the lower Chesapeake Bay. We deployed artificial substrates for mussel settlement to assess differences across sites and examine relationships with marsh conditions (e.g. cordgrass and mussel density, inundation, connectivity). After a three-month period, juvenile mussel counts were ~11x lower on substrates deployed in living shorelines than in natural marshes. An additional one-week trial revealed less than half the number of settlers at the living shoreline compared to its natural counterpart. Mussel settlement was most strongly affected by site type (living shoreline versus natural marsh) but did not exhibit any detectable relationships with the other marsh metrics. Our findings suggest that the typical marsh-sill living shoreline design may constrain early recruitment of ribbed mussels through interrupted or absent settlement cues, possibly due to altered hydrodynamics (e.g. presence of the rock sill) and/or substrate conditions. Restoration design that incorporates elements critical for larval delivery, settlement, and survival will enhance mussel recruitment, strengthen positive marsh-mussel feedbacks, and improve the resilience and ecosystem service provision of living shorelines.

Coastal nature-based solutions (NbS) have emerged as powerful tools to enhance sustainable development and ecological restoration goals. As a rapidly growing field spanning across social, political, ecological, economic, and engineering disciplines, it is critical that researchers working in coastal NbS regularly attempt to identify emerging focal areas for scientific inquiry. Following the 27th Biennial meeting of the Coastal and Estuarine Research Federation, we provide a transdisciplinary perspective (including biologists, engineers, oceanographers, geoscientists, economists, and facilitators of workforce training programs) of pertinent research questions that, if answered, will advance the effectiveness, sustainability, and widespread adoption of coastal NbS. These suggestions for future research highlight the necessity for diverse expertise and perspectives at every stage in planning, design, implementation, and monitoring coastal NbS.

Living shorelines (LSs) increasingly are implemented as a defense against coastal erosion and rising seas; however, their ecological function for wading birds has not been evaluated. Here, we compared heron and shorebird use of LSs (created fringe salt marshes with a wave break fronting the planted marshes) to natural‐fringe marshes (NFMs) in the Chesapeake Bay. We assessed the use between May and August in 2018 and 2019 at 13 tidal marsh pairs, each consisting of one LS and NFM site, with sites within pairs having similar surrounding land use and wave exposure. In each year, we assessed diurnal use with video cameras recording at least four 30‐min segments/day for a total of 677 h of video, and nocturnal/diurnal use with acoustic recording equipment recording 10‐min sound files every 2 h/day for a total of 160 h of recording. We quantified diurnal use by measuring the total time a species spent at a site, and nocturnal/diurnal use by estimating the probability of detection (i.e., presence/absence). We detected four heron and five shorebird species when data were aggregated across pairs and sampling methods. Using Bayesian mixed models, time of use did not differ between LS and NFM sites for great blue herons (Ardea herodias) and yellow‐crowned night‐herons (Nyctanassa violacea). In contrast, time of use was higher for green herons (Butorides virescens) and spotted sandpipers (Actitis macularis) at LS sites but tended to be higher for great egrets (Ardea alba) at NFM sites. The probability of detection did not differ between LS and NFM sites for great blue herons and great egrets (combined as “Ardea spp.” due to difficulty in differentiating calls under noisy conditions), yellow‐crowned night‐herons, and spotted sandpipers. Green herons and killdeer (Charadrius vociferous), however, tended to be detected more frequently at LS sites. Collectively, our research indicates that LSs are functionally equivalent to NFMs for herons and shorebirds. We hypothesize that the low‐profile rock sills of LS provide platforms for resting and preening and offer prey even when vegetated marshes are unavailable to short‐legged species during flooding tides. In addition to their established reduction of coastal erosion, LSs provide habitat for herons and shorebird species.