Background Effective nonsurgical modalities are limited in the treatment of basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). Objective We sought to evaluate the efficacy and viability of ...superficial x-ray therapy in the treatment of BCC and SCC in an outpatient setting. Methods A retrospective analysis was performed on 1715 histologically confirmed primary cutaneous BCC and SCC treated with superficial x-ray therapy at Dermatology Associates of Tallahassee in Florida between 2000 and 2010. Results Of the 1715 tumors reviewed during this period, 712 were histologically proven BCC (631 nodular and 81 superficial), 994 were SCC (861 SCC in situ and 133 invasive SCC), and 9 displayed distinct features of both BCC and SCC in the same biopsy specimen. Kaplan-Meier estimates (with 95% confidence intervals) of cumulative recurrence rates of all tumors at 2 and 5 years were 1.9% (1%-2.7%) and 5.0% (3.2%-6.7%), respectively; of BCC at 2 and 5 years were 2% (0.8%-3.3%) and 4.2% (1.9%-6.4%), respectively; and of all SCC at 2 and 5 years were 1.8% (0.8%-2.8%) and 5.8% (2.9%-8.7%), respectively. Tumors on male patients and those with a diameter greater than 2 cm were associated with a statistically significant increase in recurrence likelihood. Limitations This study represents only patients treated in 1 dermatology office in North Florida and may not be representative of the general patient population. Conclusions Superficial x-ray therapy remains a viable nonsurgical option for the treatment of primary BCC and SCC in patients where surgical intervention is declined, unadvisable, or potentially associated with significant cosmetic or functional limitations.
Dominant, habitat-forming plant species, such as seagrasses, are key components of coastal ecosystems worldwide. Multiple stressors, including invasive species that directly alter, remove, or replace ...the foundation plant species, threaten these ecosystems. On the Atlantic coast of North America, ecosystem engineering by invasive European green crab (
Carcinus maenas
) has been linked to the loss of some eelgrass (
Zostera marina
) beds. However, the interaction of the same co-occurring species on the Pacific coast has not been investigated. We conducted an enclosure experiment in Barkley Sound, British Columbia, to determine if the engineering impacts of green crabs on Pacific eelgrass ecosystems mirror those previously identified on the Atlantic coast. Eelgrass shoot density declined rapidly over 4 weeks, with a 73–81% greater loss in enclosures with high crab density compared to the low-density and control treatments. The low ratio of eelgrass blades to rhizomes in the high-density treatment suggests that blade shredding, rather than bioturbation of whole plants, was the main mechanism of eelgrass loss. Eelgrass was detected in green crab stomach contents, consistent with observations from the Atlantic coast. Crab density did not have a detectable effect on the biomass or community composition of benthic fauna associated with eelgrass over the duration of the experiment. The eelgrass loss we observed was consistent with losses observed on the Atlantic coast, which raises management concerns on the Pacific coast, particularly in areas where green crabs co-occur with other coastal stressors and with ecologically and economically important species such as salmon.
The European green crab (
Carcinus maenas
) is invasive on the West coast of North America, but the ecological consequences of this invasion remain poorly understood. Comparative functional response ...analysis has arisen as a method of elucidating ecological consequences of invasive species by comparing the impact of these species to native analogues. Through comparative functional response experiments of green crabs and native red rock crabs (
Cancer productus
) we found that green crab predation increased asymptotically (Type II functional response) when fed increasing densities of Pacific oysters (
Magallana gigas
), while red rock crab predation displayed a sigmoidal (Type III) response. At high oyster densities red rock crabs consume more Pacific oysters than green crabs do, due to their reduced handling time, though green crabs consume more Pacific oysters relative to their size than red rock crabs. However, compared to red rock crabs, green crabs consume more oysters at low prey densities, which implies that they have a larger, potentially destabilizing impact on low densities of Pacific oysters. As green crabs continue to spread across the West coast of North America, Pacific oysters will face increased predation pressure. Our results show the advantage of using functional response analysis to compare density dependent predation between an invasive species and a native species to predict the ecological consequences of invasions.
The long term survival of fecal indicator organisms (FIOs) and human pathogenic microorganisms in sediments is important from a water quality, human health and ecological perspective. Typically, both ...bacteria and viruses strongly associate with particulate matter present in freshwater, estuarine and marine environments. This association tends to be stronger in finer textured sediments and is strongly influenced by the type and quantity of clay minerals and organic matter present. Binding to particle surfaces promotes the persistence of bacteria in the environment by offering physical and chemical protection from biotic and abiotic stresses. How bacterial and viral viability and pathogenicity is influenced by surface attachment requires further study. Typically, long-term association with surfaces including sediments induces bacteria to enter a viable-but-non-culturable (VBNC) state. Inherent methodological challenges of quantifying VBNC bacteria may lead to the frequent under-reporting of their abundance in sediments. The implications of this in a quantitative risk assessment context remain unclear. Similarly, sediments can harbor significant amounts of enteric viruses, however, the factors regulating their persistence remains poorly understood. Quantification of viruses in sediment remains problematic due to our poor ability to recover intact viral particles from sediment surfaces (typically <10%), our inability to distinguish between infective and damaged (non-infective) viral particles, aggregation of viral particles, and inhibition during qPCR. This suggests that the true viral titre in sediments may be being vastly underestimated. In turn, this is limiting our ability to understand the fate and transport of viruses in sediments. Model systems (e.g., human cell culture) are also lacking for some key viruses, preventing our ability to evaluate the infectivity of viruses recovered from sediments (e.g., norovirus). The release of particle-bound bacteria and viruses into the water column during sediment resuspension also represents a risk to water quality. In conclusion, our poor process level understanding of viral/bacterial-sediment interactions combined with methodological challenges is limiting the accurate source apportionment and quantitative microbial risk assessment for pathogenic organisms associated with sediments in aquatic environments.
As the frequency of species introductions increases globally, the need for predicting the ecological impacts of invaders becomes ever more urgent. Functional responses, i.e. how resource uptake by ...consumers changes as a function of resource density, describe the species-specific ability to deplete resources under standardized conditions, and their shape has been used as a tool to predict the impact of non-native species. However, functional responses are usually derived from individuals foraging alone, which overlooks the important roles of intra- and interspecific interactions in shaping per capita consumption rates. We tested the extent to which the functional responses of invasive European green crab
Carcinus maenas
and native graceful rock crab
Metacarcinus gracilis
are affected by the perceived presence of con- and heterospecific individuals. Overall, crabs did not consume significantly more prey in the perceived presence of either a conspecific or novel heterospecific, but did demonstrate significantly higher attack rates in warmer water in the presence of a conspecific. Regardless of competitor type, green crabs consumed, on average, 16% more prey than the native crabs. This was largely due to their higher attack rate and lower prey handling time in warmer water. Green crab prey consumption increased significantly with increasing water temperature while that of the native crab species was unaffected (12 vs. 3.5% per 1°C increase, respectively). Higher maximum feeding rates are congruent with green crab impacts throughout their invaded range and suggest that green crabs might be undeterred from feeding in the presence of this co-occurring native crab species.
Understanding the density-dependent impacts of an invasive predator is integral for predicting potential consequences for prey populations. Functional response experiments are used to assess the rate ...of prey consumption and a predator’s ability to search for and consume prey at different resource densities. However, results can be highly context-dependent, limiting their extrapolation to natural ecosystems. Here, we examined how simulated habitat complexity, through the addition of substrate in which prey can escape predation, affects the functional response of invasive European green crabs (
Carcinus maenas
) foraging on two different bivalve species. Green crabs feeding on varnish clams (
Nuttallia obscurata
) shifted from a Type II hyperbolic functional response in the absence of substrate to density-independent consumption when prey could bury. Green crabs ate few Japanese littleneck clams (
Venerupis philippinarum
) under all densities, such that no functional response curve of any type could be produced and their total consumption was always density independent. However, the probability of at least one Japanese littleneck clam being consumed increased significantly with initial clam density and crab claw size across all treatments. At mean crab claw size and compared to trials without substrate, the proportion of varnish clams consumed were 4.2 times smaller when substrate was present, but substrate had a negligible effect (1.2 times) on Japanese littlenecks. The proportion of varnish clams consumed increased with crab claw size and were higher across both substrate conditions than the proportion of Japanese littlenecks consumed; however, the proportion of Japanese littleneck clams consumed increased faster with claw size than that of varnish clams. Our results suggest that including environmental features and variation in prey species can influence the density-dependent foraging described by functional response experiments. Incorporating replicable features of the natural environment into functional response experiments is imperative to make more accurate predictions about the impact of invasive predators on prey populations.
Material selection in the chemistry value chain involves consideration of many objectives, including cost, performance, health risk, and environmental impact. Alternatives assessment is an emerging ...tool for guiding complex decisions with respect to these goals. As a relatively new method, the process is not yet well developed, especially with respect to how trade‐offs among objectives can be assessed accurately and inexpensively. Using paint strippers alternatives assessment as an illustrative example, we show how an established decision‐analytic method, known as comparative screening, allows for a multistep process with gradually increasing information needs. Compared with existing methodological approaches, comparative screening instills flexible and consistent treatment of trade‐offs. This is important because it maximizes the potential for a robust assessment while minimizing arduous data collection. Further, its use in the alternatives assessment process can support the selection of more sustainable materials.
Variability in the ecological impacts of invasive species across their geographical ranges may decrease the accuracy of risk assessments. Comparative functional response analysis can be used to ...estimate invasive consumer-resource dynamics, explain impact variability, and thus potentially inform impact predictions. The European green crab (
) has been introduced on multiple continents beyond its native range, although its ecological impacts appear to vary among populations and regions. Our aim was to test whether consumer-resource dynamics under standardized conditions are similarly variable across the current geographic distribution of green crab, and to identify correlated morphological features.
Crabs were collected from multiple populations within both native (Northern Ireland) and invasive regions (South Africa and Canada). Their functional responses to local mussels (
spp.) were tested. Attack rates and handling times were compared among green crab populations within each region, and among regions (Pacific Canada, Atlantic Canada, South Africa, and Northern Ireland). The effect of predator and prey morphology on prey consumption was investigated.
Across regions, green crabs consumed prey according to a Type II (hyperbolic) functional response curve. Attack rates (i.e., the rate at which a predator finds and attacks prey), handling times and maximum feeding rates differed among regions. There was a trend toward higher attack rates in invasive than in native populations. Green crabs from Canada had lower handling times and thus higher maximum feeding rates than those from South Africa and Northern Ireland. Canadian and Northern Ireland crabs had significantly larger claws than South African crabs. Claw size was a more important predictor of the proportion of mussels killed than prey shell strength.
The differences in functional response between regions reflect observed impacts of green crabs in the wild. This suggests that an understanding of consumer-resource dynamics (e.g., the
measure of predation), derived from simple, standardized experiments, might yield useful predictions of invader impacts across geographical ranges.
To assess fecal pollution in coastal waters, current monitoring is reliant on culture-based enumeration of bacterial indicators, which does not account for the presence of viable but non-culturable ...or sediment-associated micro-organisms, preventing effective quantitative microbial risk assessment (QMRA). Seasonal variability in viable but non-culturable or sediment-associated bacteria challenge the use of fecal indicator organisms (FIOs) for water monitoring. We evaluated seasonal changes in FIOs and human enteric pathogen abundance in water and sediments from the Ribble and Conwy estuaries in the UK. Sediments possessed greater bacterial abundance than the overlying water column, however, key pathogenic species (
spp.,
spp., hepatitis A virus, hepatitis E virus and norovirus GI and GII) were not detected in sediments.
was detected in low levels in the Conwy water in spring/summer and norovirus GII was detected in the Ribble water in winter. The abundance of
and
spp. quantified by culture-based methods, rarely matched the abundance of these species when measured by qPCR. The discrepancy between these methods was greatest in winter at both estuaries, due to low CFU's, coupled with higher gene copies (GC). Temperature accounted for 60% the variability in bacterial abundance in water in autumn, whilst in winter salinity explained 15% of the variance. Relationships between bacterial indicators/pathogens and physicochemical variables were inconsistent in sediments, no single indicator adequately described occurrence of all bacterial indicators/pathogens. However, important variables included grain size, porosity, clay content and concentrations of Zn, K, and Al. Sediments with greater organic matter content and lower porosity harbored a greater proportion of non-culturable bacteria (including dead cells and extracellular DNA) in winter. Here, we show the link between physicochemical variables and season which govern culturability of human enteric pathogens and FIOs. Therefore, knowledge of these factors is critical for accurate microbial risk assessment. Future water quality management strategies could be improved through monitoring sediment-associated bacteria and non-culturable bacteria. This could facilitate source apportionment of human enteric pathogens and FIOs and direct remedial action to improve water quality.
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