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Microbes often secrete high levels of quorum sensing (QS) autoinducers into the environment to coordinate gene expression and biofilm formation, but risk detection and subsequent predation by bacterivorous predators. With such prominent signaling molecules acting as chemoattractants that diffuse into the environment at alarmingly high concentrations, it is unclear if bacterial cells can mask their chemical trails from predator detection. Here, we describe a microbial-based anti-detection adaptation, termed as “biofilm cloak”, where the biofilm prey produced biofilm matrix exopolysaccharides that “locked” and reduced the leaching of autoinducers into the milieu, thereby concealing their trails to the detection by the bacterivorous Caenorhabditis elegans nematode. The exopolysaccharides act as common good for the non-producers to hide their autoinducers from predator detection. Deficiency in chemosensory gene odr-10 in mutant animals abrogated their ability to detect autoinducers and migrate toward their prey in a directed manner, which led to lower population growth rate of animals. Hence, restriction of bacterial communication activities to the confinements of biofilms is a novel approach for predator evasion, which plays a fundamental role in shaping ecological dynamics of microbial communities and predator-prey interactions.

In nature, bacteria form biofilms by producing exopolymeric matrix that encases its entire community. While it is widely known that biofilm matrix can prevent bacterivore predation and contain virulence factors for killing predators, it is unclear if they can alter predator motility. Here, we report a novel "quagmire" phenotype, where Pseudomonas aeruginosa biofilms could retard the motility of bacterivorous nematode Caenorhabditis elegans via the production of a specific exopolysaccharide, Psl. Psl could reduce the roaming ability of C. elegans by impeding the slithering velocity of C. elegans. Furthermore, the presence of Psl in biofilms could entrap C. elegans within the matrix, with dire consequences to the nematode. After being trapped in biofilms, C. elegans could neither escape effectively from aversive stimuli (noxious blue light), nor leave easily to graze on susceptible biofilm areas. Hence, this reduced the ability of C. elegans to roam and predate on biofilms. Taken together, our work reveals a new function of motility interference by specific biofilm matrix components, and emphasizes its importance in predator-prey interactions.

Reduced efficacy of antibiotics in bacterial diseases is a global concern in clinical settings. Development of anti-virulence compounds which disarm bacterial virulence is an attractive therapeutic agent for complementary antibiotics usage. One potential target for anti-virulence compounds is quorum sensing (QS), the intercellular communication system in most pathogens, such as Pseudomonas aeruginosa. QS inhibitors (QSIs) can inhibit QS effectively, attenuate QS-mediated virulence, and improve host clearance of infections. While studies focused on developing homoserine-based las QSI, few targeted the quinolone-based pqs QS, which implicated host cytotoxicity and biofilm formation. It is imperative to develop novel anti-pqs-QS therapeutics for combinatorial antibiotic treatment of microbial diseases. We employed a gfp-based transcriptional pqs biosensor to screen a natural compounds library and identify vanillin (4-hydroxy-3-methoxybenzaldehyde), the primary phenolic aldehyde of vanilla bean. The vanillin inhibited pqs expression and its associated phenotypes, namely pyocyanin production and twitching motility in P. aeruginosa. Molecular docking results revealed that vanillin binds to the active site of PqsR, the PQS-binding response regulator. Combinatorial treatment of vanillin with antimicrobial peptide (colistin) inhibited biofilm growth in vitro and improved treatment in the in vivo C. elegans acute infection model. We demonstrated that vanillin could dampen pqs QS and associated virulence, thus providing novel therapeutic strategies against P. aeruginosa infections.

The relationship between seagrasses and pore-water hydrogen sulfide in the sediment is complex due to the opposing effects of the seagrass root system, which can reduce sulfide concentration by promoting its oxidation to sulfate, and the burial of organic matter from the plant itself, which can increase sulfide concentration by stimulating anaerobic sulfate reduction. Here, field samples of pore-water sulfide were collected in areas with and without Zostera marina shoots using Diffusive Gradients in Thin-Films (DGTs) to obtain two-dimensional visualizations of sulfide concentrations within the sediment in relation to location of eelgrass detritus and the rhizosphere. To decouple the effects of leaf detritus and the eelgrass rhizosphere on sulfide, manipulative laboratory studies were conducted over 4 weeks using 10 aquaria with or without eelgrass and different quantities of eelgrass detritus planted at 4 cm and 11 cm depths. Spatial distribution of pore-water sulfide was again measured via DGT. We found high spatial variation in pore-water sulfide concentration depending on the location analyzed relative to the rhizosphere or detritus. In the field study, pore-water sulfide concentration was greater in samples with eelgrass present, and the presence of leaf detritus accounted for higher than average sulfide concentrations in the sediment. In the laboratory experiment, sulfide concentrations localized around the leaf detritus increased with higher mass of added detritus, and sediment within the rhizosphere exhibited reduced sulfide concentrations. These results suggest that on the large scale the presence of eelgrass increases sulfide concentration, but on the smaller scale the pattern varies, with higher concentrations near buried detritus and lower concentrations near root tips.

Seagrasses are ecosystem engineers of essential marine habitat. Their populations are rapidly declining worldwide. One potential cause of seagrass population declines is wasting disease, which is caused by opportunistic pathogens in the genus Labyrinthula. While infection with these pathogens is common in seagrasses, theory suggests that disease only occurs when environmental stressors cause immunosuppression of the host. Recent evidence suggests that host factors may also contribute to disease caused by opportunistic pathogens. In order to quantify patterns of disease, identify risk factors, and investigate responses to infection, we surveyed shoot density, shoot length, epiphyte load, production of plant defenses (phenols), and wasting disease prevalence in eelgrass Zostera marina across 11 sites in the central Salish Sea (Washington state, USA), a region where both wasting disease and eelgrass declines have been documented. Wasting disease was diagnosed by the presence of necrotic lesions, and Labyrinthula cells were identified with histology. Disease prevalence among sites varied from 6 to 79%. The probability of a shoot being diseased was higher in longer shoots, in patches of higher shoot density, and in shoots with higher levels of biofouling from epiphytes. Phenolic concentration was higher in diseased leaves. We hypothesize that this results from the induction of phenols during infection. Additional research is needed to evaluate whether phenols are an adaptive defense against Labyrinthula infection. The high site-level variation in disease prevalence emphasizes the potential for wasting disease to be causing some of the observed decline in eelgrass beds.

Because photosynthesis requires CO2, carbon limitation in aquatic environments could restrict primary production and provide signals in tissue chemistry. We took advantage of spatial variability of aqueous [CO2] in estuaries to examine within-estuary variation in biometrics of intertidal eelgrass (Zostera marina) during peak summer production. As expected from the sensitivity of carbonate equilibria to pH, aqueous [CO2] increased along an ocean-to-river gradient in Willapa Bay, WA, USA. The scale of pH variability also changed, reflecting weather-driven upwelling near the ocean, tidal advection near rivers, and reduced diel fluctuation up-estuary. Z. marina studied at eight sites in the bay integrated across these different temporal fluctuations in water chemistry to exhibit increased tissue carbon and depleted δ 13C up-estuary. However, seagrass production did not change as expected from aqueous [CO2]. Instead, small standing biomass occurred at sites with organic-rich sediments or high wave energy, investment in branching showed trends along the estuarine gradient that changed seasonally, and specific growth rates based on leaf extension did not shift with the estuarine gradient or with standing biomass. These results reinforce that estuarine seagrasses are likely to experience modified mean pH and variability due not only to ocean acidification in the strict sense (anthropogenic CO2 absorbed from the atmosphere) but also from land use, upwelling, and feedbacks from biological processes. However, responses via productivity may be less evident than in tissue chemistry.

Understanding the cognitive processes used in creative practices is essential to design research. In this study, electroencephalography was applied to investigate the brain activations of visual designers when they responded to various types of word stimuli during design thinking. Thirty visual designers were recruited, with the top third and bottom third of the participants divided into high-creativity (HC) and low-creativity (LC) groups. The word stimuli used in this study were two short poems, adjectives with similar meanings, and adjectives with opposing meanings. The derived results are outlined as follows: (1) the brain activations of the designers increased in the frontal and right temporal regions and decreased in the right prefrontal region; (2) the negative association between the right temporal and middle frontal regions was notable; (3) the differences in activations caused by distinct word stimuli varied between HC and LC designers; (4) the spectral power in the middle frontal region of HC designers was lower than that of LC designers during the short love poem task; (5) the spectral power in the bilateral temporal regions of HC designers was higher than that of LC designers during the short autumn poem task; (6) the spectral power in the frontoparietal region of HC designers was lower than that of LC designers during the similar concept task; and (7) the spectral power in the frontoparietal and left frontotemporal regions of HC designers was higher than that of LC designers during the opposing concept task.

Humans are the dominant ecological and evolutionary force on the planet today, transforming habitats, polluting environments, changing climates, introducing new species, and causing other species to decline in number or go extinct. Th ese worrying anthropogenic impacts, collectively termed global change, are often viewed as a confounding factor to minimize in basic studies and a problem to resolve or quantify in applied studies. However, these ‘ accidental experiments ’ also represent opportunities to gain fundamental insight into ecological and evolutionary processes, especially when they result in perturbations that are large or long in duration and diffi cult or unethical to impose experimentally. We demonstrate this by describing important fundamental insights already gained from studies which utilize global change factors as accidental experiments. In doing so, we highlight why accidental experiments are sometimes more likely to yield insights than traditional approaches. Next, we argue that emerging environmental problems can provide even more opportunities for scientifi c discovery in the future, and provide both examples and guidelines for moving forward. We recommend 1) a greater fl ow of information between basic and applied subfi elds of ecology and evolution to identify emerging opportunities; 2) considering the advantages of the ‘ accidental experiment ’ approach relative to more traditional approaches; and 3) planning for the challenges inherent to uncontrolled accidental experiments. We emphasize that we do not view the accidental experiments provided by global change as replacements for scientifi c studies quantifying the magnitude of anthropogenic impacts or outlining strategies for mitigating impacts. Instead, we believe that accidental experiments are uniquely situated to provide insights into evolutionary and ecological processes that ultimately allow us to better predict and manage change on our human-dominated planet.

By changing ecosystem processes and altering the physical landscape, invasive ecosystem engineers can have substantial impacts on ecosystem functions and human economies and may facilitate other non-native species. Eradication programs in terrestrial and aquatic systems aim to reverse the impacts of invasive species and return the system to its pre-invasion conditions. Despite an extensive focus on the impacts of both native and non-native ecosystem engineers, the consequences of removing invasive ecosystem engineers, particularly in coastal ecosystems, are largely unknown. In this study, we quantified changes in a benthic community following the eradication of the invasive ecosystem engineer, hybrid cordgrass Spartina, in San Francisco Bay, California. We used field experimental manipulations to test for persistent effects of both aboveground and belowground structural modifications of the invasive plant on the benthic community. We found significant effects of the invasive plant more than four years following eradication. Experimental modification of the above- vs. belowground structure of this ecosystem engineer revealed taxonomic specific effects resulting in hysteresis in the recovery of the benthic food webs. We found that these “legacy effects” resulted from two specific mechanisms: (1) delayed breakdown of belowground structures (stems, roots) and (2) persistence of other invasive species whose invasion was facilitated by the ecosystem engineer. Both of these mechanisms are likely to occur in similar systems where belowground structures breakdown more slowly or where other associated long-lived invaders persist. Our work is among the first to quantify the slow rate of change in food web and community processes and the persistent legacy effects of an invasive ecosystem engineer in a coastal ecosystem. We suggest that this delayed transition to pre-invasion conditions could resemble an alternate state that would be misidentified without a sufficient monitoring interval or recovery duration, with consequences for future management and restoration activity planning.

This study aimed to examine the brain activations of designers during visual association and identify the differences in brain activations caused by distinct visual stimulus types among designers with different creativity levels. Twenty-one professional production designers were recruited and divided into three groups. The top third and bottom third of the participants (7 for each) were divided into high creativity (HC) and low creativity (LC) groups for neural comparison analyses. The derived results are outlined as follows: (i) The brain activations of the production designers notably increased in the prefrontal and parietal regions during visual association; (ii) the spectral power of most HC designers was lower than that of the LC designers; (iii) realist art stimulation evoked strong activation in the anterior ventral regions, whereas abstract art stimulation primarily activated the posterior regions; (iv) the differences in brain activations between the HC and LC designers resulting from realist art stimulation were generally larger than were those resulting from abstract art stimulation; and (v) the brain activations of the HC designers resulting from abstract art stimulation were stronger than were those resulting from realist art stimulation, whereas an opposite trend was observed in the LC designers. Few studies to date have empirically explored the relationship between the creativity levels of designers and their visual association. Enhancing the creative performance of designers should feature among the primary goals of the design industry and design education. This study elucidates a novel approach in this critical research area, although further studies are necessary.

The National Science Education Standards have highlighted the importance of active learning and reflection for contemporary scientific methods in K–12 classrooms, including the use of models. Computer modeling and visualization are tools that researchers employ in their scientific inquiry process, and often computer models are used in collaborative projects across disciplines. The goal of this project was to develop and field-test a module that used a computer model to teach marine sciences content in an applied, inquiry-based, and collaborative manner. Students used an estuarine transport model to explore the question of how circulation patterns affect planktonic organisms, demonstrating the interdisciplinary interaction of physics and biology. Our experience suggests that computer models, when used for inquiry, can help foster students' understanding of the nature of science and critical-thinking skills.

Both tropical and temperate species are responding to global warming through range shifts, but our understanding of the consequences of these shifts for whole communities is limited. Here, we use current elevational range data for six taxonomic groups spanning 90 in latitude to examine the potential impacts of climate-driven range shifts on community change, or disassembly, across latitude. Elevational ranges are smaller at low latitudes for most groups and, as a consequence, tropical communities appear to be more sensitive to temperature increases compared with temperate communities. Under site-specific temperature projections, we generally found greater community disassembly in tropical compared with temperate communities, although this varied by dispersal assumptions. Mountain height can impact the amount of community disassembly, with greater change occurring on smaller mountains. Finally, projected community disassembly was higher for ectotherms than endotherms, although the variation among ectotherms was greater than the variation separating endotherms and ectotherms.

We used stable-isotope (δD) measurements of primary feathers to demonstrate that Northern Rough-winged Swallows (Stelgidopteryx serripennis) that breed in western North America migrate to the monsoon region of northwest Mexico for their annual postbreeding molt. Both adults and juveniles replace all their primaries in late summer. As expected, in samples of adults and fledglings collected at a northern breeding locality in eastern Washington, primary δD values of adults were of southern origin, whereas those of fledglings, whose feathers were grown in the nest, were consistent with their northern origin. Similarly, some young birds collected as they were replacing primaries in northwest Mexico had a southern signature in newly replaced primaries but a northern signature in their yet unreplaced juvenile primaries, which indicates that they were molt migrants from the north. Feather OD values increased from P1 to P9 in breeding adults collected in upstate New York. In the eastern United States, bo...

Dwarf eelgrass (duckgrass; Zostera japonica) and Manila clams (Ruditapes philippinarum) are two introduced species that co-occur on intertidal flats of the northeast Pacific. Through factorial manipulation of clam (0, 62.5, 125 clams m−2) and eelgrass density (present, removed by hand, harrowed), we examined intra- and interspecific effects on performance, as well as modification of the physical environment. The presence of eelgrass reduced water flow by up to 40% and was also observed to retain water at low tide, which may ameliorate desiccation and explain why eelgrass grew faster in the presence of conspecifics (positive feedback). Although shell growth of small (20–50 mm) clams was not consistently affected by either treatment in this 2-month experiment, clam condition improved when eelgrass was removed. Reciprocally, clams at aquaculture densities had no effect on eelgrass growth, clam growth and condition, or porewater nutrients. Overall, only Z. japonica demonstrated strong population-level interactions. Interspecific results support an emerging paradigm that invasive marine ecosystem engineers often negatively affect infauna. Positive feedbacks for Z. japonica may characterize its intraspecific effects particularly at the stressful intertidal elevation of this study (+1 m above mean lower low water).

SUMMARY Most basidiomycete fungi actively eject their spores. The process begins with the condensation of a water droplet at the base of the spore. The fusion of the droplet onto the spore creates a momentum that propels the spore forward. The use of surface tension for spore ejection offers a new paradigm to perform work at small length scales. However, this mechanism of force generation remains poorly understood. To elucidate how fungal spores make effective use of surface tension, we performed a detailed mechanical analysis of the three stages of spore ejection: the transfer of energy from the drop to the spore, the work of fracture required to release the spore from its supporting structure and the kinetic energy of the spore after ejection. High-speed video imaging of spore ejection in Auricularia auriculaand Sporobolomyces yeasts revealed that drop coalescence takes place over a short distance (∼5 μm) and energy transfer is completed in less than 4 μs. Based on these observations, we developed an explicit relation for the conversion of surface energy into kinetic energy during the coalescence process. The relation was validated with a simple artificial system and shown to predict the initial spore velocity accurately (predicted velocity: 1.2 m s–1; observed velocity: 0.8 m s–1 for A. auricula). Using calibrated microcantilevers, we also demonstrate that the work required to detach the spore from the supporting sterigma represents only a small fraction of the total energy available for spore ejection. Finally, our observations of this unique discharge mechanism reveal a surprising similarity with the mechanics of jumping in animals.

In contrast to secondary succession, studies of terrestrial primary succession largely ignore the role of biotic interactions, other than plant facilitation and competition, despite the expectation that simplified interaction webs and propagule-dependent demographics may amplify the effects of consumers and mutualists. We investigated whether successional context determined the impact of consumers and mutualists by quantifying their effects on reproduction by the shrub Vaccinium membranaceum in primary and secondary successional sites at Mount St. Helens (Washington, USA), and used simulations to explore the effects of these interactions on colonization. Species interactions differed substantially between sites, and the combined effect of consumers and mutualists was much more strongly negative for primary successional plants. Because greater local control of propagule pressure is expected to increase successional rates, we evaluated the role of dispersal in the context of these interactions. Our simulations showed that even a small local seed source greatly increases population growth rates, thereby balancing strong consumer pressure. The prevalence of strong negative interactions in the primary successional site is a reminder that successional communities will not exhibit the distribution of interaction strengths characteristic of stable communities, and suggests the potential utility of modeling succession as the consequence of interaction strengths.