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  1. Free, publicly-accessible full text available April 1, 2023
  2. Oysters are described as estuarine ecosystem engineers because their reef structures provide habitat for a variety of flora and fauna, alter hydrodynamics, and affect sediment composition. To what spatial extent oyster reefs influence surrounding infauna and sediment composition remains uncertain. We sampled sediment and infauna across 8 intertidal mudflats at distances up to 100 m from oyster reefs within coastal bays of Virginia, USA, to determine if distance from reefs and physical site characteristics (reef elevation, local hydrodynamics, and oyster cover) explain the spatial distributions of infauna and sediment. Total infauna density increased with distance away from reefs; however, themore »opposite was observed for predatory crustaceans (primarily crabs). Our results indicate a halo surrounding the reefs of approximately 40 m (using an increase in ~25% of observance as the halo criterion). At 90 m from reefs, bivalves and gastropods were 70% more likely to be found (probability of observance), while there was an approximate 4-fold decrease for large crustaceans compared to locations adjacent to reefs. Increases in percent oyster reef cover and/or mean reef area did not statistically alter infauna densities but showed a statistical correlation with smaller sediment grain size, increased organic matter, and reduced flow rates. Weaker flow conditions within the surrounding mudflats were also associated with smaller grain sizes and higher organic matter content, suggesting multiple drivers on the spatial distribution of sediment composition. This study emphasizes the complexity of bio-physical couplings and the considerable spatial extent over which oyster reefs engineer intertidal communities.« less
    Free, publicly-accessible full text available March 24, 2023
  3. Free, publicly-accessible full text available March 1, 2023
  4. Habitat suitability models have been used for decades to develop spatially explicit predictions of landscape capacity to support populations of target species. As high-resolution remote sensing data are increasingly included in habitat suitability models that inform spatial conservation and restoration decisions, it is essential to validate model predictions with independent, quantitative data collected over sustained time frames. Here, we used data collected from 12 reefs over a 14 yr sampling period to validate a recently developed physical habitat suitability model for intertidal oyster reefs in coastal Virginia, USA. The model used intertidal elevation, water residence time, and fetch to predictmore »the likelihood of suitable conditions for eastern oysters Crassostrea virginica across a coastal landscape, and remotely sensed elevation was the most restrictive parameter in the model. Model validation revealed that adult oyster biomass was on average 1.5 times greater on oyster reefs located in predicted ‘suitable’ habitat relative to reefs located in predicted ‘less suitable’ habitat over the 14 yr sampling period. By validating this model with long-term population data, we highlight the importance of elevation as a driver of sustained intertidal oyster success. These findings extend the validation of habitat suitability models by quantitatively supporting the inclusion of remotely sensed data in habitat suitability models for intertidal species. Our results suggest that future oyster restoration and aquaculture projects could enhance oyster biomass by using habitat suitability models to select optimal site locations.« less
    Free, publicly-accessible full text available February 3, 2023
  5. Aquatic eddy covariance (AEC) is increasingly being used to study benthic oxygen (O 2 ) flux dynamics, organic carbon cycling, and ecosystem health in marine and freshwater environments. Because it is a noninvasive technique, has a high temporal resolution (∼15 min), and integrates over a large area of the seafloor (typically 10–100 m 2 ), it has provided new insights on the functioning of aquatic ecosystems under naturally varying in situ conditions and has given us more accurate assessments of their metabolism. In this review, we summarize biogeochemical, ecological, and biological insightsgained from AEC studies of marine ecosystems. A generalmore »finding for all substrates is that benthic O 2 exchange is far more dynamic than earlier recognized, and thus accurate mean values can only be obtained from measurements that integrate over all timescales that affect the local O 2 exchange. Finally, we highlight new developments of the technique, including measurements of air–water gas exchange and long-term deployments.« less
    Free, publicly-accessible full text available January 3, 2023
  6. Free, publicly-accessible full text available January 1, 2023
  7. Free, publicly-accessible full text available January 1, 2023
  8. Abstract The spatial pattern of vegetation patchiness may follow universal characteristic rules when the system is close to critical transitions between alternative states, which improves the anticipation of ecosystem-level state changes which are currently difficult to detect in real systems. However, the spatial patterning of vegetation patches in temperature-driven ecosystems have not been investigated yet. Here, using high-resolution imagery from 1972 to 2013 and a stochastic cellular automata model, we show that in a North American coastal ecosystem where woody plant encroachment has been happening, the size distribution of woody patches follows a power law when the system approaches amore »critical transition, which is sustained by the local positive feedbacks between vegetation and the surrounding microclimate. Therefore, the observed power law distribution of woody vegetation patchiness may be suggestive of critical transitions associated with temperature-driven woody plant encroachment in coastal and potentially other ecosystems.« less
    Free, publicly-accessible full text available December 1, 2022
  9. Abstract Cyclic guanosine monophosphate-adenosine monophosphate (cGAMP), produced by cyclic GMP-AMP synthase (cGAS), stimulates the production of type I interferons (IFN). Here we show that cGAMP activates DNA damage response (DDR) signaling independently of its canonical IFN pathways. Loss of cGAS dampens DDR signaling induced by genotoxic insults. Mechanistically, cGAS activates DDR in a STING-TBK1-dependent manner, wherein TBK1 stimulates the autophosphorylation of the DDR kinase ATM, with the consequent activation of the CHK2-p53-p21 signal transduction pathway and the induction of G1 cell cycle arrest. Despite its stimulatory activity on ATM, cGAMP suppresses homology-directed repair (HDR) through the inhibition of polyADP-ribosylation (PARylation),more »in which cGAMP reduces cellular levels of NAD + ; meanwhile, restoring NAD + levels abrogates cGAMP-mediated suppression of PARylation and HDR. Finally, we show that cGAMP also activates DDR signaling in invertebrate species lacking IFN ( Crassostrea virginica and Nematostella vectensis ), suggesting that the genome surveillance mechanism of cGAS predates metazoan interferon-based immunity.« less
    Free, publicly-accessible full text available December 1, 2022
  10. Abstract Shorelines and their ecosystems are endangered by sea-level rise. Nature-based coastal protection is becoming a global strategy to enhance coastal resilience through the cost-effective creation, restoration and sustainable use of coastal wetlands. However, the resilience to sea-level rise of coastal wetlands created under Nature-based Solution has been assessed largely on a regional scale. Here we assess, using a meta-analysis, the difference in accretion, elevation, and sediment deposition rates between natural and restored coastal wetlands across the world. Our results show that restored coastal wetlands can trap more sediment and that the effectiveness of these restoration projects is primarily drivenmore »by sediment availability, not by wetland elevation, tidal range, local rates of sea-level rise, and significant wave height. Our results suggest that Nature-based Solutions can mitigate coastal wetland vulnerability to sea-level rise, but are effective only in coastal locations where abundant sediment supply is available.« less
    Free, publicly-accessible full text available December 1, 2022