Search for: All records

Context Reversing global declines of foundation species requires recovery of critical bottlenecks in population dynamics, particularly the recruitment of early life stages. Understanding the controls on recruitment can substantially improve restoration success. Objectives We investigated how geophysical conditions and restoration history determine recruitment in eastern oysters (Crassostrea virginica), a foundation species requiring substantial restoration efforts following severe, widespread losses. Methods Over 3 years, we measured annual oyster recruitment to standardized ceramic tiles on 9–16 intertidal reefs in coastal Virginia, USA. We paired these measurements with an 18-year time series of recruitment to natural substrate on 8 natural reference reefs and 44 restored reefs (0–16 years post-construction). Results Recruitment to tiles was highly correlated with recruitment to natural substrate, validating our methodology. Recruitment was positively spatially autocorrelated within 1 km and increased 9–14 × with moderate wind fetch. A one-meter increase in substrate elevation tripled recruitment. Recruitment was 4 × higher on natural reefs compared to restored reefs, regardless of elapsed time since restoration. Geospatial model predictions identified 6% (24 km2) of intertidal areas as highly suitable for oyster recruitment, offering a refined target for restoration practitioners. Conclusions By integrating multi-year field studies, long-term monitoring, and habitat suitability modeling, our research identified environmental conditions favorable for oyster recruitment, offering insights that could enhance restoration planning and population resilience. Our findings provide actionable insights for optimizing oyster restoration by targeting areas with favorable wind fetch and elevation. These results offer valuable guidance for spatial planning in restoration and may inform strategies for other species where recruitment limits restoration success. 

This dataset contains measurements of Eastern oyster (Crassostrea virginica) recruitment to standardized ceramic tiles deployed across intertidal oyster reef sites in the Virginia Coast Reserve. Recruitment is defined as the number of macroscopic oyster recruits (less than or equal to 25 mm shell height) per square centimeter of tile surface, capturing settlement and early post-settlement survival. Data were collected in 2018, 2019, and 2021 across 9-16 reef sites per year, including both natural and restored reefs. The dataset supports research on spatial and environmental drivers of oyster recruitment and has been validated against natural reef substrate data for comparability. 

This dataset has been superceded by Lusk, B., R. Smith, and M.C.N. Castorani. 2024. Oyster fauna lengths, counts, and biomass from restored and reference reefs in Virginia coastal bays, 2005-2023 ver 1. Environmental Data Initiative. https://doi.org/10.6073/pasta/d68de69f29cee5f737313a07f813f245 (Accessed 2024-02-22). which includes additional years and parameters. Oyster and associated reef fauna counts and lengths were sampled at 16 natural reference reefs and 61 restored shell plant reefs located at 18 sites in the Virginia Coast Reserve. Overfishing and disease decimated oyster reefs in the Virginia Coast Reserve in the 1900s. Reference reefs were defined as remnant reefs that naturally recovered in the early 2000s to develop the pronounced vertical structure and multiple oyster size classes that represent the desired endpoint of restoration efforts. Nearly every year since 2003, The Nature Conservancy and Virginia Marine Resource Commission have constructed oyster reefs in intertidal areas in the VCR. To construct the restored reefs, practitioners applied dredged, fossilized oyster shell to intertidal locations chosen for their bottom stability and accessibility (locations lacked oysters prior to construction). Whelk shell supplemented the oyster shell at 9 of the restored reefs. 

Oyster reef fauna counts and lengths were sampled at natural "reference" reefs and restored shell plant reefs located in the Virginia Coast Reserve. Overfishing and disease decimated oyster reefs in the Virginia Coast Reserve in the 1900s. Reference reefs were defined as remnant reefs that naturally recovered in the early 2000s to develop the pronounced vertical structure and multiple oyster size classes that represent the desired endpoint of restoration efforts. Nearly every year since 2003, The Nature Conservancy and Virginia Marine Resource Commission have constructed oyster reefs in intertidal areas in the VCR. To construct the restored reefs, practitioners launched dredged, fossilized oyster shell from barges to intertidal locations chosen for their bottom stability and accessibility (locations lacked oysters prior to construction). Whelk shell supplemented the oyster shell at some of the restored reefs. TNC practitioners monitor select restored and reference reefs annually for adult and spat live oysters, adult and spat box oysters, mud crabs, mud snails, oyster drills, live clams, and mussels. 

Abstract Spatial synchrony is the tendency for population fluctuations to be correlated among different locations. This phenomenon is a ubiquitous feature of population dynamics and is important for ecosystem stability, but several aspects of synchrony remain unresolved. In particular, the extent to which any particular mechanism, such as dispersal, contributes to observed synchrony in natural populations has been difficult to determine. To address this gap, we leveraged recent methodological improvements to determine how dispersal structures synchrony in giant kelp (Macrocystis pyrifera), a global marine foundation species that has served as a useful system for understanding synchrony. We quantified population synchrony and fecundity with satellite imagery across 11 years and 880 km of coastline in southern California, USA, and estimated propagule dispersal probabilities using a high‐resolution ocean circulation model. Using matrix regression models that control for the influence of geographic distance, resources (seawater nitrate), and disturbance (destructive waves), we discovered that dispersal was an important driver of synchrony. Our findings were robust to assumptions about propagule mortality during dispersal and consistent between two metrics of dispersal: (1) the individual probability of dispersal and (2) estimates of demographic connectivity that incorporate fecundity (the number of propagules dispersing). We also found that dispersal and environmental conditions resulted in geographic clusters with distinct patterns of synchrony. This study is among the few to statistically associate synchrony with dispersal in a natural population and the first to do so in a marine organism. The synchronizing effects of dispersal and environmental conditions on foundation species, such as giant kelp, likely have cascading effects on the spatial stability of biodiversity and ecosystem function. 

Abstract Biodiversity can stabilize ecological communities through biological insurance, but climate and other environmental changes may disrupt this process via simultaneous ecosystem destabilization and biodiversity loss. While changes to diversity–stability relationships (DSRs) and the underlying mechanisms have been extensively explored in terrestrial plant communities, this topic remains largely unexplored in benthic marine ecosystems that comprise diverse assemblages of producers and consumers. By analyzing two decades of kelp forest biodiversity survey data, we discovered changes in diversity, stability, and their relationships at multiple scales (biological organizational levels, spatial scales, and functional groups) that were linked with the most severe marine heatwave ever documented in the North Pacific Ocean. Moreover, changes in the strength of DSRs during/after the heatwave were more apparent among functional groups than both biological organizational levels (population vs. ecosystem levels) and spatial scales (local vs. broad scales). Specifically, the strength of DSRs decreased for fishes, increased for mobile invertebrates and understory algae, and were unchanged for sessile invertebrates during/after the heatwave. Our findings suggest that biodiversity plays a key role in stabilizing marine ecosystems, but the resilience of DSRs to adverse climate impacts primarily depends on the functional identities of ecological communities. 

Cross-ecosystem subsidies are critical to ecosystem structure and function, especially in recipient ecosystems where they are the primary source of organic matter to the food web. Subsidies are indicative of processes connecting ecosystems and can couple ecological dynamics across system boundaries. However, the degree to which such flows can induce cross-ecosystem cascades of spatial synchrony, the tendency for system fluctuations to be correlated across locations, is not well understood. Synchrony has destabilizing effects on ecosystems, adding to the importance of understanding spatiotemporal patterns of synchrony transmission. In order to understand whether and how spatial synchrony cascades across the marine-terrestrial boundary via resource subsidies, we studied the relationship between giant kelp forests on rocky nearshore reefs and sandy beach ecosystems that receive resource subsidies in the form of kelp wrack (detritus). We found that synchrony cascades from rocky reefs to sandy beaches, with spatiotemporal patterns mediated by fluctuations in live kelp biomass, wave action, and beach width. Moreover, wrack deposition synchronized local abundances of shorebirds that move among beaches seeking to forage on wrack-associated invertebrates, demonstrating that synchrony due to subsidies propagates across trophic levels in the recipient ecosystem. Synchronizing resource subsidies likely play an underappreciated role in the spatiotemporal structure, functioning, and stability of ecosystems.