Primary production of the kelp Lessonia corrugata varies with season and water motion: Implications for coastal carbon cycling.

Kelp forests provide vital ecosystem services such as carbon storage and cycling, and understanding primary production dynamics regarding seasonal and spatial variations is essential. We conducted surveys at three sites in southeast Tasmania, Australia, that had different levels of water motion, across four seasons to determine seasonal primary production and carbon storage as living biomass for kelp beds of Lessonia corrugata (Order Laminariales). We quantified blade growth, erosion rates, and the variation in population density and estimated both the net biomass accumulation (NBA) per square meter and the carbon standing stock. We observed a significant difference in blade growth and erosion rates between seasons and sites. Spring had the highest growth rate (0.02 g C · blade-1 · d-1 ) and NBA (1.62 g C · m-2 · d-1 ), while summer had the highest blade erosion (0.01 g C · blade-1 · d-1 ), with a negative NBA (-1.18 g C · m-2 · d-1 ). Sites exhibiting lower blade erosion rates demonstrated notably greater NBA than sites with elevated erosion rates. The sites with the highest water motion had the slowest erosion rates. Moreover, the most wave-exposed site had the densest populations, resulting in the highest NBA and a greater standing stock. Our results reveal a strong seasonal and water motion influence on carbon dynamics in L. corrugata populations. This knowledge is important for understanding the dynamics of the carbon cycle in coastal regions.

Thermal performance curves identify seasonal and site-specific variation in the development of Ecklonia radiata (Phaeophyceae) gametophytes and sporophytes.

Rapid ocean warming is affecting kelp forests globally. While the sporophyte life stage has been well studied for many species, the microscopic life stages of laminarian kelps have been understudied, particularly regarding spatial and temporal variations in thermal tolerance and their interaction. We investigated the thermal tolerance of growth, survival, development, and fertilization of Ecklonia radiata gametophytes, derived from zoospores sampled from two sites in Tasmania, Australia, throughout a year, over a temperature gradient (3-30°C). For growth we found a relatively stable thermal optimum at ~20.5°C and stable thermal maxima (25.3-27.7°C). The magnitude of growth was highly variable and depended on season and site, with no consistent spatial pattern for growth and gametophyte size. Survival also had a relatively stable thermal optimum of ~17°C, 3°C below the optimum for growth. Gametophytes grew to single cells between 5 and 25°C, but sporophytes were only observed between 10 and 20°C, indicating reproductive failure outside this range. The results reveal complex effects of source population and season of collection on gametophyte performance in E. radiata, with implications when comparing results from material collected at different localities and times. In Tasmania, gametophytes grow considerably below the estimated thermal maxima and thermal optima that are currently only reached during summer heatwaves, whereas optima for survival (~17°C) are frequently reached and surpassed during heatwaves, which may affect the persistence and recruitment of E. radiata in a warmer climate.

Universal logic with encoded spin qubits in silicon.

Quantum computation features known examples of hardware acceleration for certain problems, but is challenging to realize because of its susceptibility to small errors from noise or imperfect control. The principles of fault tolerance may enable computational acceleration with imperfect hardware, but they place strict requirements on the character and correlation of errors1. For many qubit technologies2-21, some challenges to achieving fault tolerance can be traced to correlated errors arising from the need to control qubits by injecting microwave energy matching qubit resonances. Here we demonstrate an alternative approach to quantum computation that uses energy-degenerate encoded qubit states controlled by nearest-neighbour contact interactions that partially swap the spin states of electrons with those of their neighbours. Calibrated sequences of such partial swaps, implemented using only voltage pulses, allow universal quantum control while bypassing microwave-associated correlated error sources1,22-28. We use an array of six 28Si/SiGe quantum dots, built using a platform that is capable of extending in two dimensions following processes used in conventional microelectronics29. We quantify the operational fidelity of universal control of two encoded qubits using interleaved randomized benchmarking30, finding a fidelity of 96.3% ± 0.7% for encoded controlled NOT operations and 99.3% ± 0.5% for encoded SWAP. The quantum coherence offered by enriched silicon5-9,16,18,20,22,27,29,31-37, the all-electrical and low-crosstalk-control of partial swap operations1,22-28 and the configurable insensitivity of our encoding to certain error sources28,33,34,38 all combine to offer a strong pathway towards scalable fault tolerance and computational advantage.

Lung Cancer Diagnosed Through Screening, Lung Nodule, and Neither Program: A Prospective Observational Study of the Detecting Early Lung Cancer (DELUGE) in the Mississippi Delta Cohort.

PURPOSE: Lung cancer screening saves lives, but implementation is challenging. We evaluated two approaches to early lung cancer detection-low-dose computed tomography screening (LDCT) and program-based management of incidentally detected lung nodules. METHODS: A prospective observational study enrolled patients in the early detection programs. For context, we compared them with patients managed in a Multidisciplinary Care Program. We compared clinical stage distribution, surgical resection rates, 3- and 5-year survival rates, and eligibility for LDCT screening of patients diagnosed with lung cancer. RESULTS: From 2015 to May 2021, 22,886 patients were enrolled: 5,659 in LDCT, 15,461 in Lung Nodule, and 1,766 in Multidisciplinary Care. Of 150, 698, and 1,010 patients diagnosed with lung cancer in the respective programs, 61%, 60%, and 44% were diagnosed at clinical stage I or II, whereas 19%, 20%, and 29% were stage IV (P = .0005); 47%, 42%, and 32% had curative-intent surgery (P < .0001); aggregate 3-year overall survival rates were 80% (95% CI, 73 to 88) versus 64% (60 to 68) versus 49% (46 to 53); 5-year overall survival rates were 76% (67 to 87) versus 60% (56 to 65) versus 44% (40 to 48), respectively. Only 46% of 1,858 patients with lung cancer would have been deemed eligible for LDCT by US Preventive Services Task Force (USPSTF) 2013 criteria, and 54% by 2021 criteria. Even if all eligible patients by USPSTF 2021 criteria had been enrolled into LDCT, the Nodule Program would have detected 20% of the stage I-II lung cancer in the entire cohort. CONCLUSION: LDCT and Lung Nodule Programs are complementary, expanding access to early lung cancer detection and curative treatment to different-risk populations. Implementing Lung Nodule Programs may alleviate emerging disparities in access to early lung cancer detection.

The Relative Survival Impact of Guideline-Concordant Clinical Staging and Stage-Appropriate Treatment of Potentially Curable Non-Small Cell Lung Cancer.

BACKGROUND: Lung cancer management guidelines strive to improve outcomes. Theoretically, thorough staging promotes optimal treatment selection. We examined the association between guideline-concordant invasive mediastinal nodal staging, guideline-concordant treatment, and non-small cell lung cancer survival. RESEARCH QUESTION: What is the current practice of invasive mediastinal nodal staging for patients with lung cancer in a structured multidisciplinary care environment? Is guideline-concordant staging associated with guideline-concordant treatment? How do they relate to survival? STUDY DESIGN AND METHODS: We evaluated patients with nonmetastatic non-small cell lung cancer diagnosed from 2014 through 2019 in the Multidisciplinary Thoracic Oncology Program of the Baptist Cancer Center, Memphis, Tennessee. We examined patterns of mediastinal nodal staging and stage-stratified treatment, grouping patients into cohorts with guideline-concordant staging alone, guideline-concordant treatment alone, both, or neither. We evaluated overall survival with Kaplan-Meier curves and Cox proportional hazards models. RESULTS: Of 882 patients, 456 (52%) received any invasive mediastinal staging. Seventy-four percent received guideline-concordant staging; guideline-discordant staging decreased from 34% in 2014 to 18% in 2019 (P < .0001). Recipients of guideline-concordant staging were more likely to receive guideline-concordant treatment (83% vs 66%; P < .0001). Sixty-one percent received both guideline-concordant invasive mediastinal staging and guideline-concordant treatment; 13% received guideline-concordant staging alone; 17% received guideline-concordant treatment alone; and 9% received neither. Survival was greatest in patients who received both (adjusted hazard ratio [aHR], 0.41; 95% CI, 0.26-0.63), followed by those who received guideline-concordant treatment alone (aHR, 0.60; 95% CI, 0.36-0.99), and those who received guideline-concordant staging alone (aHR, 0.64; 95% CI, 0.37-1.09) compared with neither (P < .0001, log-rank test). INTERPRETATION: Levels of guideline-concordant staging were high, were rising, and were associated with guideline-concordant treatment selection in this multidisciplinary care cohort. Guideline-concordant staging and guideline-concordant treatment were complementary in their association with improved survival, supporting the connection between these two processes and lung cancer outcomes.

Plastic and natural inorganic microparticles do not differ in their effects on adult mussels (Mytilidae) from different geographic regions.

Microplastics are ubiquitous in the marine environment and studies on their effects on benthic filter feeders at least partly revealed a negative influence. However, it is still unclear whether the effects of microplastics differ from those of natural suspended microparticles, which constitute a common stressor in many coastal environments. We present a series of experiments that compared the effects of six-week exposures of marine mussels to two types of natural particles (red clay and diatom shells) to two types of plastic particles (Polymethyl Methacrylate and Polyvinyl Chloride). Mussels of the family Mytilidae from temperate regions (Japan, Chile, Tasmania) through subtropical (Israel) to tropical environments (Cabo Verde) were exposed to concentrations of 1.5 mg/L, 15 mg/L and 150 mg/L of the respective microparticles. At the end of this period, we found significant effects of suspended particles on respiration rate, byssus production and condition index of the animals. There was no significant effect on clearance rate and survival. Surprisingly, we observed only small differences between the effects of the different types of particles, which suggests that the mussels were generally equally robust towards exposure to variable concentrations of suspended solids regardless of whether they were natural or plastic. We conclude, that microplastics and suspended solids elicit similar effects on the tested response variables, and that both types of microparticles mainly cause acute responses rather than more persistent carry-over effects.

Density-dependence and seasonal variation in reproductive output and sporophyte production in the kelp, Ecklonia radiata.

The kelp, Ecklonia radiata, is an abundant subtidal ecosystem engineer in southern Australia. Density-dependent changes in the abiotic environment engineered by Ecklonia may feedback to affect reproduction and subsequent recruitment. Here, we examined: 1) how the reproductive capacity of Ecklonia individuals in the field (zoospores released · mm-2 reproductive tissue) varied with adult density and time, and 2) how the recruitment of microscopic gametophytes and sporophytes was influenced by zoospore density at two times. Zoospore production did not vary with adult density, with only one month out of ten sampled over a 2-y period showing a significant effect of density. However, zoospore production varied hugely over time, being generally highest in mid-autumn and lowest in mid-late summer. There were strong effects of initial zoospore density on gametophyte and sporophyte recruitment with both a minimum and an optimum zoospore density for sporophyte recruitment, but these varied in time. Almost no sporophytes developed when initial zoospore density was <6.5 · mm-2 in spring or <0.5 · mm-2 in winter with optimum densities of 90-355 · mm-2 in spring and 21-261 · mm-2 in winter, which resulted in relatively high recruitment of 4-7 sporophytes · mm-2 . Sporophyte recruitment declined at initial zoospore densities >335 · mm-2 in spring and >261 · mm-2 in winter and was zero at very high zoospore densities. These findings suggest that although adult Ecklonia density does not affect per-capita zoospore production, because there is a minimum zoospore density for sporophyte production, a decline in population-level output could feedback to impact recruitment.

A Flexible Design Platform for Si/SiGe Exchange-Only Qubits with Low Disorder.

Spin-based silicon quantum dots are an attractive qubit technology for quantum information processing with respect to coherence time, control, and engineering. Here we present an exchange-only Si qubit device platform that combines the throughput of CMOS-like wafer processing with the versatility of direct-write lithography. The technology, which we coin "SLEDGE", features dot-shaped gates that are patterned simultaneously on one topographical plane and subsequently connected by vias to interconnect metal lines. The process design enables nontrivial layouts as well as flexibility in gate dimensions, material selection, and additional device features such as for rf qubit control. We show that the SLEDGE process has reduced electrostatic disorder with respect to traditional overlapping gate devices with lift-off metallization, and we present spin coherent exchange oscillations and single qubit blind randomized benchmarking data.

Survival Impact of an Enhanced Multidisciplinary Thoracic Oncology Conference in a Regional Community Health Care System.

INTRODUCTION: We compared NSCLC treatment and survival within and outside a multidisciplinary model of care from a large community health care system. METHODS: We implemented a rigorously benchmarked "enhanced" Multidisciplinary Thoracic Oncology Conference (eMTOC) and used Tumor Registry data (2011-2017) to evaluate guideline-concordant care. Because eMTOC was located in metropolitan Memphis, we separated non-MTOC patient by metropolitan and regional location. We categorized National Comprehensive Cancer Network guideline-concordant treatment as "preferred," or "appropriate" (allowable under certain circumstances). We compared demographic and clinical characteristics across cohorts using chi-square tests and survival using Cox regression, adjusted for multiple testing. We also performed propensity-matched and adjusted survival analyses. RESULTS: Of 6259 patients, 14% were in eMTOC, 55% metropolitan non-MTOC, and 31% regional non-MTOC cohorts. eMTOC had the highest rates of African Americans (34% versus 28% versus 22%), stages I to IIIB (63 versus 40 versus 50), urban residents (81 versus 78 versus 20), stage-preferred treatment (66 versus 57 versus 48), guideline-concordant treatment (78 versus 70 versus 63), and lowest percentage of nontreatment (6 versus 21 versus 28); all p values were less than 0.001. Compared with eMTOC, hazard for death was higher in metropolitan (1.5, 95% confidence interval: 1.4-1.7) and regional (1.7, 1.5-1.9) non-MTOC; hazards were higher in regional non-MTOC versus metropolitan (1.1, 1.0-1.2); all p values were less than 0.05 after adjustment. Results were generally similar after propensity analysis with and without adjusting for guideline-concordant treatment. CONCLUSIONS: Multidisciplinary NSCLC care planning was associated with significantly higher rates of guideline-concordant care and survival, providing evidence for rigorous implementation of this model of care.

Interactive effects of canopy-driven changes in light, scour and water flow on microscopic recruits in kelp.

Ecosystem engineering kelp forms habitat and influences associated communities by altering abiotic conditions. These conditions can also affect the engineer's own demographic rates but the mechanisms underpinning these feedbacks are not well known. Here, we tested the interactive effects of three abiotic factors engineered by the Australasian kelp Ecklonia radiata (light, water flow and scour) on the early survivorship and growth of its outplanted microscopic recruits. After six weeks, recruit survivorship was high in the absence of scour and low light (2-3 times higher than when scour was present) and under low water flow-ambient light conditions. Growth of sporophytes was strongly related to light, with recruits under ambient light approximately four times larger after six weeks. Overall, reduced scour (for survivorship) and ambient light (for growth) appear crucial for maximising E. radiata recruitment suggesting a healthy forest can provide microenvironments to enhance survivorship while gaps in the canopy enhance growth.

Homoseongomycin, a compound isolated from marine actinomycete bacteria K3-1, is a potent inhibitor of encephalitic alphaviruses.

Marine microorganisms have been a resource for novel therapeutic drugs for decades. In addition to anticancer drugs, the drug acyclovir, derived from a marine sponge, is FDA-approved for the treatment of human herpes simplex virus-1 infections. Most alphaviruses that are infectious to terrestrial animals and humans, such as Venezuelan and eastern equine encephalitis viruses (VEEV and EEEV), lack efficient antiviral drugs and it is imperative to develop these remedies. To push the discovery and development of anti-alphavirus compounds forward, this study aimed to isolate and screen for potential antiviral compounds from cultured marine microbes originating from the marine environment. Compounds from marine microbes were of interest as they are prolific producers of bioactive compounds across the spectrum of human diseases and infections. Homoseongomycin, an actinobacteria isolated from a marine sponge displayed impressive activity against VEEV from a total of 76 marine bioactive products. The 50% effective concentration (EC50) for homoseongomycin was 8.6 µM for suppressing VEEV TC-83 luciferase reporter virus replication. Homoseongomycin was non-toxic up to 50 µM and partially rescued cells from VEEV induced cell death. Homoseongomycin exhibited highly efficient antiviral activity with a reduction of VEEV infectious titers by 8 log10 at 50 µM. It also inhibited EEEV replication with an EC50 of 1.2 µM. Mechanism of action studies suggest that homoseongomycin affects both early and late stages of the viral life cycle. Cells treated with 25 µM of homoseongomycin had a ~90% reduction in viral entry. In comparison, later stages showed a more robust reduction in infectious titers (6 log10) and VEEV extracellular viral RNA levels (4 log10), but a lesser impact on intracellular viral RNA levels (1.5 log10). In sum, this work demonstrates that homoseongomycin is a potential anti-VEEV and anti-EEEV compound due to its low cytotoxicity and potent antiviral activity.

Risk factors for mortality and progression to severe COVID-19 disease in the Southeast region in the United States: A report from the SEUS Study Group.

OBJECTIVE: Identify risk factors that could increase progression to severe disease and mortality in hospitalized SARS-CoV-2 patients in the Southeast region of the United States. DESIGN, SETTING, AND PARTICIPANTS: Multicenter, retrospective cohort including 502 adults hospitalized with laboratory-confirmed COVID-19 between March 1, 2020, and May 8, 2020 within 1 of 15 participating hospitals in 5 health systems across 5 states in the Southeast United States. METHODS: The study objectives were to identify risk factors that could increase progression to hospital mortality and severe disease (defined as a composite of intensive care unit admission or requirement of mechanical ventilation) in hospitalized SARS-CoV-2 patients in the Southeast United States. RESULTS: In total, 502 patients were included, and 476 of 502 (95%) had clinically evaluable outcomes. The hospital mortality rate was 16% (76 of 476); 35% (177 of 502) required ICU admission and 18% (91 of 502) required mechanical ventilation. By both univariate and adjusted multivariate analyses, hospital mortality was independently associated with age (adjusted odds ratio [aOR], 2.03 for each decade increase; 95% confidence interval [CI], 1.56--2.69), male sex (aOR, 2.44; 95% CI, 1.34-4.59), and cardiovascular disease (aOR, 2.16; 95% CI, 1.15-4.09). As with mortality, risk of severe disease was independently associated with age (aOR, 1.17 for each decade increase; 95% CI, 1.00-1.37), male sex (aOR, 2.34; 95% CI, 1.54-3.60), and cardiovascular disease (aOR, 1.77; 95% CI, 1.09-2.85). CONCLUSIONS: In an adjusted multivariate analysis, advanced age, male sex, and cardiovascular disease increased risk of severe disease and mortality in patients with COVID-19 in the Southeast United States. In-hospital mortality risk doubled with each subsequent decade of life.

Demography of the Intertidal Fucoid Hormosira banksii: Importance of Recruitment to Local Abundance.

Canopy-forming macroalgae form the basis of diverse coastal ecosystems globally. The fucoid Hormosira banksii is often the dominant canopy-forming macroalga in the temperate intertidal of southern Australia and New Zealand, where it is commonly associated with an understory of coralline turf. Hormosira banksii is susceptible to both natural and anthropogenic disturbance and despite its abundance, few studies have examined the demography of this important species. This study determined the demographic response of H. banksii to different gradients of disturbance to both its canopy and to the understory coralline turf. We established plots in which the density of H. banksii and/or understory coralline turf was manipulated in a pulse perturbation to simulate a disturbance event. The manipulated plots contained eight treatments ranging from 100% removal of H. banksii to 100% removal of the understory coralline turf. We then measured recruitment and followed individual recruits for up to 18 months to determine growth and survivorship. We found that H. banksii recruitment was seasonally variable throughout the experiment and highest over summer, survivorship of recruits was generally high, and the species was slow-growing and long-lived. Moreover, the level of disturbance did not seem to affect recruitment, growth, or survivorship and post-recruitment mortality was independent of H. banksii density. In this system, it appears that H. banksii is a relatively long-lived perennial species whose demography is density-independent which appears to allow recovery from disturbance.

A comparison with natural particles reveals a small specific effect of PVC microplastics on mussel performance.

Effects of microplastics on marine taxa have become a focal point in marine experimental biology. Almost all studies so far, however, assessed the influence of microplastics on animals only in relation to a zero-particle group. Documented microplastic impacts may thus be overestimated, since many marine species also experience natural suspended solids as a stressor. Here, we compared the effects of polyvinyl chloride (PVC) and red clay (mean for both particles: ~12-14 µm) on the Mediterranean mussel Mytilus galloprovincialis across three particle concentrations (1.5, 15, 150 mg l-1). Exposure to PVC for 35 days lowered mussel body condition index by 14% in relation to clay, but no difference in byssus production, respiration and survival rates emerged between the two particle types. This suggests that the effects of synthetic particles on filter feeders may emulate those of natural suspended solids, and highlights the importance of including natural particles in microplastic exposure studies.

Dataset for concurrent echosounder and ADCP measurements at a tidal energy candidate site in Australia.

Interaction uncertainties between tidal energy devices and marine animals have the potential to impede the tidal energy industry as it moves closer towards commercial-scale array installations. Developing standardised environmental impact assessment (EIA) practices would allow for potential impact concerns to the marine environment to be identified and mitigated early during project development. In an effort to help formulate a standardised EIA framework that addresses knowledge gaps in fish-current interactions at tidal energy candidate sites, Scherelis et al. [1] presented a case study for investigating changes in fish aggregations in response to changing environmental conditions including tidal currents at a tidal energy candidate site in Australia prior to turbine installation. Here, we present the dataset utilised for this study titled "Investigating biophysical linkages at tidal energy candidate sites: a case study for combining environmental assessment and resource characterisation" [1]. The dataset includes tidal current information from an Acoustic Doppler Current Profiler (ADCP), volume backscattering measurements from a four-frequency biological echosounder (Acoustic Zooplankton and Fish Profiler - AZFP) as an indicator for fish biomass, and fish aggregation metrics calculated from volume backscatter in post-processing. ADCP and AZFP were installed on a bottom-mounted mooring and engaged in a concurrent sampling plan for ∼2.5 months from December 2018 to February 2019. The mooring was deployed in the Banks Strait, a tidal energy candidate site located in the northeast of Tasmania, Australia, at a location favourable for tidal turbine installations considering current speed, depth, substrate, sediment type and proximity to shore. The ADCP dataset includes current velocity and direction measurements at 1 m vertical and 1-min time intervals. The raw AZFP dataset includes volume backscattering strength collected in 4-s time intervals with a vertical resolution of 0.072 m in raw, and 0.1 m in pre-processed form. Several post-processing steps were implemented to mitigate changes in background noise due to current speed and wind stress, and to isolate acoustic fish returns from remaining scattering sources. Once isolated, volume backscatter containing fish targets underwent post-processing to determine fish aggregation metrics including density, abundance, centre of mass, dispersion,% water column occupied, evenness, and index for aggregation. Each aggregation metric was then binned by minute matched with corresponding environmental conditions for current speed, shear, temperature, diel stage, and tidal stage. Raw and processed datasets for the AZFP and ADCP are provided. Post-processed data includes the derived fish aggregation metrics along with corresponding environmental conditions. The described datasets are freely available on the Australian Ocean Data Network (AODN).

Habitat provided by native species facilitates higher abundances of an invader in its introduced compared to native range.

The impacts invasive species have on biodiversity and ecosystem function globally have been linked to the higher abundances they often obtain in their introduced compared to native ranges. Higher abundances of invaders in the introduced range are often explained by a reduction in negative species interactions in that range, although results are equivocal. The role of positive interactions in explaining differences in  the abundance of invaders between native and invasive ranges has not been tested. Using biogeographic surveys, we showed that the rocky shore porcelain crab, Petrolisthes elongatus, was ~4 times more abundant in its introduced (Tasmania, Australia) compared to its native (New Zealand) range. The habitat of these crabs in the invaded range (underside of intertidal boulders) was extensively covered with the habitat-forming tubeworm Galeolaria caespitosa. We tested whether the habitat provided by the tubeworm facilitates a higher abundance of the invasive crab by creating mimics of boulders with and without the tubeworm physical structure and measured crab colonisation into these habitats at three sites in both Tasmania and New Zealand. Adding the tubeworm structure increased crab abundance by an average of 85% across all sites in both ranges. Our intercontinental biogeographic survey and experiment demonstrate that native species can facilitate invader abundance and that positive interactions can be important drivers of invasion success.

Facilitation of an invader by a native habitat-former increases along interacting gradients of environmental stress.

Native habitat-forming species can facilitate invasion by reducing environmental stress or consumer pressure. However, the intensity of one stressor along a local gradient may differ when expanding the scale of observation to encompass major variations in background environmental conditions. In this study, we determined how facilitation of the invasive porcelain crab, Petrolisthes elongatus, by the native tube-forming serpulid, Galeolaria caespitosa, varied with environmental gradients at local (tidal height) and larger (wave exposure) spatial scales. G. caespitosa constructs a complex calcareous matrix on the underside of intertidal boulders and we predicted that its positive effects on P. elongatus density would increase in intensity with shore height and be stronger at wave-sheltered than wave-exposed locations. To test these predictions, we conducted two experiments. First, we determined the effects of serpulid presence (boulders with live or dead serpulid matrix vs. bare boulders) at six shore heights that covered the intertidal distribution of P. elongatus. Second, we determined the effects of serpulid presence (present vs. absent), shore height (high vs. low) and wave exposure (sheltered vs. exposed) on crabs across six locations within the invaded range in northern Tasmania, Australia. In Experiment 1, the presence of serpulids (either dead or alive) enhanced P. elongatus densities at all shore heights, with facilitation intensity (as determined by a relative interaction index; RII) tending to increase with shore height. In Experiment 2, serpulids facilitated P. elongatus across shore heights and wave exposures, although crab densities were lower at high shore levels of wave-sheltered locations. However, the intensity of crab facilitation by serpulids was greater on wave-sheltered than on wave-exposed shores, but only at the high shore level. This study demonstrates that local effects of native habitat-formers on invasive species are dependent on prevailing environmental conditions at larger spatial scales and that, under more stressful conditions, invaders become increasingly reliant on positive interactions with native habitat-formers. Increased strength of local-scale facilitation by native species, dampening broader scale variations in environmental stressors, could enhance the ability of invasive species to establish self-sustaining populations in the invaded range.

Identification of Portimine B, a New Cell Permeable Spiroimine That Induces Apoptosis in Oral Squamous Cell Carcinoma.

Spiroimines are a class of compounds produced by marine dinoflagellates with a wide range of toxicity and therapeutic potential. The smallest of the cyclic imines, portimine, is far less toxic than other known members in several animal models. Portimine has also been shown to induce apoptosis and reduce the growth of a variety of cancer cell lines at low nanomolar concentrations. In an effort to discover new spiroimines, the current study undertook a metabolomic analysis of cultures of cyclic imine-producing dinoflagellates, and a new analog of portimine was discovered in which the five-membered cyclic ether is open. Further scrutiny with human oral cavity squamous cell carcinoma (OCSCC) cell lines revealed that the open ring congener was less potent than portimine A but could still lead to the accumulation of apoptotic gene transcripts, fragment genomic DNA, and reduce cancer cell proliferation in the range of 100-200 nM.

Resilience and stability of kelp forests: The importance of patch dynamics and environment-engineer feedbacks.

Habitat forming 'ecosystem engineers' such as kelp species create complex habitats that support biodiverse and productive communities. Studies of the resilience and stability of ecosystem engineers have typically focussed on the role of external factors such as disturbance. However, their population dynamics are also likely to be influenced by internal processes, such that the environmental modifications caused by engineer species feedback to affect their own demography (e.g. recruitment, survivorship). In numerous regions globally, kelp forests are declining and experiencing reductions in patch size and kelp density. To explore how resilience and stability of kelp habitats is influenced by this habitat degradation, we created an array of patch reefs of various sizes and supporting adult Ecklonia radiata kelp transplanted at different densities. This enabled testing of how sub-canopy abiotic conditions change with reductions in patch size and adult kelp density, and how this influenced demographic processes of microscopic and macroscopic juvenile kelp. We found that ecosystem engineering by adult E. radiata modified the environment to reduce sub-canopy water flow, sedimentation, and irradiance. However, the capacity of adult kelp canopy to engineer abiotic change was dependent on patch size, and to a lesser extent, kelp density. Reductions in patch size and kelp density also impaired the recruitment, growth and survivorship of microscopic and macroscopic juvenile E. radiata, and even after the provisioning of established juveniles, demographic processes were impaired in the absence of sufficient adult kelp. These results are consistent with the hypothesis that ecosystem engineering by adult E. radiata facilitates development of juvenile conspecifics. Habitat degradation seems to impair the ability of E. radiata to engineer abiotic change, causing breakdown of positive intraspecific feedback and collapse of demographic functions, and overall, leading to reductions in ecosystem stability and resilience well before local extirpation.