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Intraspecific variation in host susceptibility to individual parasite species is common, yet how these effects scale to mediate the structure of diverse parasite communities in nature is less well understood. To address this knowledge gap, we tested how host genetic identity affects parasite communities on restored reefs seeded with juvenile oysters from different sources—a regional commercial hatchery or one of two wild progenitor lines. We assessed prevalence and intensity of three micro- and two macroparasite species for 4 years following restoration. Despite the spatial proximity of restored reefs, oyster source identity strongly predicted parasite community prevalence across all years, with sources varying in their relative susceptibility to different parasites. Oyster seed source also predicted reef-level parasite intensities across space and through time. Our results highlight that host intraspecific variation can shape parasite community structure in natural systems, and reinforce the importance of considering source identity and diversity in restoration design.

Fluid (air or water) movements are key determinants of living systems from cellular to community levels of organization. Water flow can influence individual fitness and local population dynamics, but less is known about the collective response of natural communities to alteration in water flow because parameter responses to flow may be additive, juxtaposed, or interactive. To examine how changes in water flow affected initial larval settlement patterns of epifaunal and infaunal animals, colonization of larger individuals, and prey survival, we manipulated water flow (−50% or +47%) in situ using large wooden channels over small experimental oyster reefs. To test whether initial settlement patterns were additive or influenced by early post‐settlement processes (i.e., predation or competition reduced the densities), we compared patterns in short‐duration trials (two weeks) to those in longer duration deployments (six weeks). We found that minor changes in water flow (5–10 cm s⁻¹) resulted in large changes in settlement of many species, predation levels, and the modification of initial settlement patterns. Settlement (two‐week intervals) and subsequent recruitment (six‐week intervals) increased for several species as flow rate increased. For most species, this relationship peaked at mid‐level flows (mud crabs, barnacles, and bivalves), whereas others (oysters) continued to increase with higher flow rates. Settlement patterns were best preserved in recruitment under high flow conditions where post‐settlement mortality was lower. Collectively, our results demonstrate how biological and physical processes are coupled in oyster reef systems, with relatively minor changes in water flow affecting pre‐ and post‐settlement processes.

Within estuarine and coastal ecosystems globally, extensive habitat degradation and loss threaten critical ecosystem functions and necessitate widescale restoration efforts. There is abundant evidence that ecological processes and species interactions can vary with habitat characteristics, which has important implications for the design and implementation of restoration efforts aimed at enhancing specific ecosystem functions and services. We conducted an experiment examining how habitat characteristics (presence; edge vs. interior) influence the communities of resident fish and mobile invertebrates on restored oyster (Crassostrea virginica) reefs. Similar to previous studies, we found that restored reefs altered community composition and augmented total abundance and biomass relative to unstructured sand habitat. Community composition and biomass also differed between the edge and interior of individual reefs as a result of species‐specific patterns over small spatial scales. These patterns were only weakly linked to oyster density, suggesting that other factors that vary between edge and interior (e.g. predator access or species interactions) are likely more important for community structure on oyster reefs. Fine‐scale information on resident species' use of oyster reefs will help facilitate restoration by allowing decision makers to optimize the amount of edge versus interior habitat. To improve the prediction of faunal use and benefits from habitat restoration, we recommend investigations into the mechanisms shaping edge and interior preferences on oyster reefs.

Understanding the diffusion of innovative ideas, behaviors, and technologies could reduce disconnects between conservation science and management, such as the science‐practice gap between biodiversity research and restoration practice. To assess knowledge uptake as an indicator of diffusion of innovation in restoration practice, we conducted an online survey of two organizations focused on coastal habitat restoration: Coastal and Estuarine Research Federation (CERF) and International Coral Reef Society (ICRS). We evaluated experience restoring particular habitats, along with perceptions of the purpose of restoration, the metrics used to evaluate restoration success, and the challenges to successful restoration. We then examined the perceived importance of genetic diversity for restoration success as an indicator of knowledge‐practice transfer in conservation strategy. The practice of coastal habitat restoration diverged by organization and habitat: a higher percentage of CERF members had restored oysters, marshes, and seagrasses compared to ICRS, whereas the reverse was true for corals. Views of the purpose of restoration, the site selection process, and the challenges to successful restoration were similar. Despite similarities in perceptions of the restoration process, the two organizations had variable indications of knowledge‐practice transfer: ICRS respondents ranked the importance of genetic diversity as a restoration strategy higher than did CERF respondents. The perceived importance of genetic diversity also differed by habitat, with both CERF and ICRS respondents ranking diversity as more important for corals. The more successful transfer of knowledge to practice in the coral community indicates that the disconnect between genetic diversity research and restoration practice is surmountable. In addition, it serves as a potential strategy for promoting the spread of innovative restoration practices to achieve long‐term recovery of ecosystems.

When prey alter behavioral or morphological traits to reduce predation risk, they often incur fitness costs through reduced growth and reproduction as well as increased mortality that are known as nonconsumptive effects (NCEs). Environmental context and trophic structure can individually alter the strength of NCEs, yet the interactive influence of these contexts in natural settings is less understood. At six sites across 1000 km of the Southeastern Atlantic Bight (SAB), we constructed oyster reefs with one, two, or three trophic levels and evaluated the traits of focal juvenile oysters exposed to predation risk cues. We monitored environmental variables (water flow velocity, microalgal resources, and oyster larval recruitment) that may have altered how oysters respond to risk, and we also assessed the cost of trait changes to oyster mortality and growth when they were protected from direct predatory loss. Regardless of trophic structure, we found that oyster shell strength and natural oyster recruitment peaked at the center of the region. This high recruitment negated the potential for NCEs by smothering and killing the focal oysters. Also independent of trophic structure, focal oysters grew the most at the northernmost site. In contrast to, and perhaps because of, these strong environmental effects, the oyster traits of condition index and larval recruitment were only suppressed by the trophic treatment with a full complement of risk cues from intermediate and top predators at just the southernmost site. But at this same site, statistically significant NCEs on oyster growth and mortality were not detected. More strikingly, our study demonstrated environmental gradients that differentially influence oysters throughout the SAB. In particular, the results of our trophic manipulation experiment across these gradients suggest that in the absence of predation, environmental differences among sites may overwhelm the influence of NCEs on prey traits and population dynamics.