Substantial losses of the seagrass Posidonia oceanica have initiated investigations into localized resilience declines related to anthropogenic disturbances. In this study, we determined ...reconstructed shoot age and interannual growth metrics can detect anthropogenic impact effects on P. oceanica production. Interannual rhizome vertical growth, leaf production, and demographics of shoots collected from sewage and trawling impacted areas were examined using mixed effects modeling. Detected impact effects were specific to the type of impact, manifesting as an older-skewed age distribution of sewage outfall shoots and reduced vertical growth and reduced leaf production of trawling site shoots. A stress event period was also detected for all shoots >5 years old, with trawling impacted shoots indicating little recovery. Reconstructed age and growth metrics are simple to measure, incorporate multiple years of in situ shoot development, and are advantageous for identification of declining P. oceanica resilience prior to catastrophic losses.
•Localized stressors lower Posidonia oceanica resilience to larger-scale disturbances.•We examined stress impacts through reconstruction of P. oceanica life history.•Sewage and trawling impacts were elucidated using reconstruction methods.•The way P. oceanica life history was influenced differed by stressor type.•Trawl impacted seagrass showed evidence of low recovery from large-scale stressor.
Pseudogymnoascus destructans is a fungal pathogen responsible for a deadly disease among North American bats known as white-nose syndrome (WNS). Since detection of WNS in the United States in 2006, ...its rapid spread and high mortality has challenged development of treatment and prevention methods, a significant objective for wildlife management agencies. In an effort to mitigate precipitous declines in bat populations due to WNS, we have developed and implemented a multi-year mitigation strategy at Black Diamond Tunnel (BDT), Georgia, singly known as one of the most substantial winter colony sites for tricolored bats (Perimyotis subflavus), with pre-WNS abundance exceeding 5000 individuals. Our mitigation approach involved in situ treatment of bats at the colony level through aerosol distribution of antifungal volatile organic compounds (VOCs) that demonstrated an in vitro ability to inhibit P. destructans conidia germination and mycelial growth through contact-independent exposure. The VOCs evaluated have been identified from microbes inhabiting naturally-occurring fungistatic soils and endophytic fungi. These VOCs are of low toxicity to mammals and have been observed to elicit antagonism of P. destructans at low gaseous concentrations. Cumulatively, our observations resolved no detrimental impact on bat behavior or health, yet indicated a potential for attenuation of WNS related declines at BDT and demonstrated the feasibility of this novel disease management approach.
Fluoreno2,1- a fluorene, a molecule comprising fused ortho -quinodimethane units in a 1,5-napthoquinodimethane core, has been prepared and investigated with spectroscopy (UV-Vis-NIR, 1 H-NMR and ...Raman), SQUID magnetometry, spectroelectrochemistry and quantum chemistry. While para -quinodimethanes with a 2,6-substitution pattern exist as closed-shell species and meta -quinodimethanes with 2,7-substitution favour a ground electronic state with very large diradical character, our 1,5-substituted ortho -naphthoquinodimethane-based system exhibits an intermediate degree of diradical character.
•Seagrasses can be subjected to a wide range of environmental variability in the coastal environment.•Phenotypic variation can be a highly effective strategy for seagrass survival in sub-optimal ...environments.•We examine phenotypic variation of separate Thalassia testudinum populations on a large spatial scale.•Northern Gulf environments are more variable, while the Florida Keys environment is more suitable.•Northern Gulf shoots were smaller, exhibited shorter lifespans, and higher flowering intensity.
Phenotypic variability is a valuable adaptive mechanism for seagrass species that exist in a dynamic environment and can lead to significant intraspecific regional distinctions in life history. Research is lacking in studies examining the significance of within-species phenotypic variation in relation to gradients in environmental condition at a large spatial scale. These studies are essential to better understanding the potential for acclimatization and tolerance capabilities of seagrasses in declining coastal environments. Thalassia testudinum (turtlegrass) is a ubiquitous keystone seagrass species across the Caribbean and Gulf of Mexico (GoM) that populates both environmentally dynamic estuaries and stable coastal environments. In order to elucidate environmentally driven distinctions in spatially separated populations, we examined characteristics of shoots exposed to widely separated distinct coastal environments with varying degrees of environmental stability and suitability. In our comparison, three sampling locations vary considerably in ambient water temperature, salinity, and water column clarity along a gradient from oscillating, higher stress conditions to stable, more favorable conditions. Shoots tended to have larger leaves with more biomass in the stable environment and also exhibited an older shoot age structure and higher horizontal expansion rate. However, shoots in the more variable, higher stress environment exhibited greater evidence of flowering and first flowered at an earlier age. The results elucidate large spatially distinct and environmentally relevant differences in morphology, growth, and life history highlighting the need for more studies regarding phenotypic variability of seagrass populations across environmental gradients.
Tidal marshes are a key component of coastal seascape mosaics that support a suite of socially and economically valuable ecosystem services, including recreational opportunities (e.g., fishing, ...birdwatching), habitat for fisheries species, improved water quality, and shoreline protection. The capacity for tidal marshes to support these services is, however, threatened by increasingly widespread human impacts that reduce the extent and condition of tidal marshes across multiple spatial scales and that vary substantially through time. Climate change causes species redistribution at continental scales, changes in weather patterns (e.g., rainfall), and a worsening of the effect of coastal squeeze through sea level rise. Simultaneously, the effects of urbanization such as habitat loss, eutrophication, fishing, and the spread of invasive species interact with each other, and with climate change, to fundamentally change the structure and functioning of tidal marshes and their food webs. These changes affect tidal marshes at local scales through changes in plant community composition, complexity, and condition and at regional scales through changes in habitat extent, configuration, and connectivity. However, research into the full effects of these multi-scaled, interactive stressors on ecosystem service provision in tidal marshes is in its infancy and is somewhat geographically restricted. This hinders our capacity to quickly and effectively curb loss and degradation of both tidal marshes and the services they deliver with targeted management actions. We highlight ten priority research questions seeking to quantify the consequences and scales of human impacts on tidal marshes that should be answered to improve management and restoration plans.
Competitive interactions between native and nonindigenous species occur under conditions of ongoing environmental alterations related to urbanization and climate change, presenting a challenge to ...understanding invasiveness. Indigenous submerged aquatic vegetation species have been negatively impacted by nutrient enrichment and saltwater intrusion, while simultaneously experiencing a rapid spread in nonindigenous competitors. To better predict future shifts in freshwater macrophyte community dominance, investigations need to consider how these multiscale disturbances influence competitiveness of nonindigenous macrophytes. Using an outdoor greenhouse mesocosm setup for approximately 19 weeks over the course of subtropical winter, we experimentally examined how nutrient enrichment, salinity, and the interaction of both factors influence the competitive interactions between a native macrophyte with moderate salinity tolerance, wild celery (Vallisneria americana), and a highly invasive macrophyte with lower salinity tolerance, hydrilla (Hydrilla verticillata). We tested the factors of macrophyte composition (hydrilla monoculture, wild celery monoculture, or biculture), salinity (0, 4, or 8), and fertilization (ambient or fertilized) on biomass production, biomass allocation, and morphological metrics as responses to environmental condition and interspecific competition. Fertilizer enhanced wild celery leaf area (more than twofold) and shifted allocation toward aboveground biomass, but did not enhance hydrilla competitiveness. Salinity negatively affected wild celery leaf area (by 7.5%–67.8%) and biomass (by 4%–15%) and also reduced hydrilla belowground biomass production (by 6%–25%) but did not influence competition. An interaction effect of fertilizer and salinity negatively influenced hydrilla growth, however the combined factors did not influence competitive outcomes. The lack of evidence for a competitive advantage by hydrilla in this study demonstrates that salinity exposure sufficiently limits a highly invasive plant's competitive abilities and subsequent suppression of a native species.
Climate change is altering naturally fluctuating environmental conditions in coastal and estuarine ecosystems across the globe. Departures from long-term averages and ranges of environmental ...variables are increasingly being observed as directional changes e.g., rising sea levels, sea surface temperatures (SST) and less predictable periodic cycles (e.g., Atlantic or Pacific decadal oscillations) and extremes (e.g., coastal flooding, marine heatwaves). Quantifying the short- and long-term impacts of climate change on tidal marsh seascape structure and function for nekton is a critical step toward fisheries conservation and management. The multiple stressor framework provides a promising approach for advancing integrative, cross-disciplinary research on tidal marshes and food web dynamics. It can be used to quantify climate change effects on and interactions between coastal oceans (e.g., SST, ocean currents, waves) and watersheds (e.g., precipitation, river flows), tidal marsh geomorphology (e.g., vegetation structure, elevation capital, sedimentation), and estuarine and coastal nekton (e.g., species distributions, life history adaptations, predator-prey dynamics). However, disentangling the cumulative impacts of multiple interacting stressors on tidal marshes, whether the effects are additive, synergistic, or antagonistic, and the time scales at which they occur, poses a significant research challenge. This perspective highlights the key physical and ecological processes affecting tidal marshes, with an emphasis on the trophic linkages between marsh production and estuarine and coastal nekton, recommended for consideration in future climate change studies. Such studies are urgently needed to understand climate change effects on tidal marshes now and into the future.
The 2010 Deepwater Horizon (DwH) oil spill in the Gulf of Mexico discharged ~3.19 million barrels of oil into Gulf waters, making it one of the largest marine disasters in history in terms of volume. ...We report on the results of a study to assess oil impacts to coastal fishes and invertebrates. Using two-decades of fisheries-independent data in coastal Alabama and Mississippi, we document variability following both natural and anthropogenic disturbances from two periods pre-DwH (1997–2001 and 2007–2009), one intra-spill period for acute DwH effects (2010–2012) and one period post-spill for chronic, longer-term impacts (2014–2017). Results indicated significant changes to community structure, relative abundance, and diversity in the intra-spill period. Causation for changes is confounded by variables such as behavioral emigration, altered freshwater inflow, death of consumers, and the mandated fishery closure. Results highlight the need for long-term, comprehensive monitoring/observing systems to provide adequate background for assessing future disturbances.
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•The 2010 Deepwater Horizon oil spill is one of the largest marine spills in history.•Using 2 decades of trawl data, we found significant changes in nekton communities.•Changes were driven by increases of select species.•This was likely driven by a combination of oil toxicity and confounding variables.
White-nose syndrome (WNS) is a disease among hibernating North American bats caused by the psychrophilic fungus Pseudogymnoascus destructans. Since its discovery in New York state, US, in 2006, and ...as of 2020, WNS has rapidly spread to 34 American states and seven Canadian provinces, causing precipitous declines of native bat populations across North America. The rapid spread of this fungal pathogen has been facilitated by the social behavior of bats, as well as the ability of subterranean hibernacula to support a favorable environment for P. destructans, and is probably exacerbated by anthropogenic transmission events. Although many bat species roost in natural cave environments, bats also selectively use diverse structures for hibernacula. Certain areas of the US lack caves, forcing bats to select different winter roosting environments. Bats have been observed using roadway-associated structures, such as bridges and culverts, for roosting, especially in regions that lack natural cave environments. However, the potential for P. destructans transmission in such roadway-associated structures requires further investigation. Understanding potential pathogen transmission in these widely used anthropogenic structures is crucial to disease management and preventing further declines of imperiled bat populations. Our study investigated these structures as potential pathogen transmission corridors by surveying the use of these structures by Perimyotis subflavus and other susceptible bat populations and by measuring their temperature. The results suggest the environments of roadway-associated culverts are thermally conducive to the proliferation of P. destructans—even in regions with mild winters—and the development of WNS in susceptible bat populations. It is apparent these roadway-associated structures have the potential to spread P. destructans and exacerbate the effect of WNS on susceptible bat populations.
![Fluoreno[2,1- a ]fluorene: ...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/1359-7345/small "Fluoreno[2,1- a ]fluorene: an ortho -naphthoquinodimethane-based system with partial diradical character")
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