Minimizing invasion risk by reducing propagule pressure: a model for ballast-water exchange

Biological invasions are a major and increasing agent of global biodiversity change. Theory and practice indicate that invasion risk can be diminished by reducing propagule pressure, or the quantity, quality, and frequency of introduced individuals. For aquatic invasions, the primary global invasion pathway is ballast-water transport, and the primary risk reduction strategy is currently open-ocean exchange. Exchange was developed with shipping between freshwater ports in mind, but the majority of shipping connects brackish and marine ports. A worldwide convention, adopted in 2004 by the International Maritime Organization, now mandates ballast-water exchange (or equivalent management) for its 164 member states. Will exchange be as effective in reducing invasion risk for euryhaline species (those capable of tolerating a wide range of salinity levels) in salt-water ports? Here we develop a simple mathematical framework for optimizing ballast-water exchange in terms of exchange level, timing, and species salinity tolerance. Our model shows that when species survival is worse in the post-exchange than in the pre-exchange water, exchange is always effective. However, when survival is equal or better following exchange, a critical level and timing are required for effective exchange. We illustrate the model\u27s applications with a variety of introduced marine and estuarine organisms

The National Early Warning Score and its subcomponents recorded within ±24 hours of emergency medical admission are poor predictors of hospital-acquired acute kidney injury

YesBackground: Hospital-acquired Acute Kidney Injury (H-AKI) is a common cause of avoidable morbidity and mortality. Aim: To determine if the patients’ vital signs data as defined by a National Early Warning Score (NEWS), can predict H-AKI following emergency admission to hospital. Methods: Analyses of emergency admissions to York hospital over 24-months with NEWS data. We report the area under the curve (AUC) for logistic regression models that used the index NEWS (model A0), plus age and sex (A1), plus subcomponents of NEWS (A2) and two-way interactions (A3). Likewise for maximum NEWS (models B0,B1,B2,B3). Results: 4.05% (1361/33608) of emergency admissions had H-AKI. Models using the index NEWS had the lower AUCs (0.59 to 0.68) than models using the maximum NEWS AUCs (0.75 to 0.77). The maximum NEWS model (B3) was more sensitivity than the index NEWS model (A0) (67.60% vs 19.84%) but identified twice as many cases as being at risk of H-AKI (9581 vs 4099) at a NEWS of 5. Conclusions: The index NEWS is a poor predictor of H-AKI. The maximum NEWS is a better predictor but seems unfeasible because it is only knowable in retrospect and is associated with a substantial increase in workload albeit with improved sensitivity.The Health Foundatio

Body size variation in the sexually dimorphic scaphopod Rhabdus rectius (Carpenter, 1864) (Dentaliida: Rhabdidae)

Male-biased sexual size dimorphism typically evolves via sexual selection for larger males that are favoured by choosy females or are more successful in mate competition with other males. Among marine invertebrates that broadcast their gametes into the ocean for fertilisation, this form of sexual size dimorphism is rare because such species lack direct interactions among males or between the sexes. However, the broadcast-spawning tusk shell Rhabdus rectius was recently reported to show strong male-biased sexual size dimorphism. That pattern might imply interesting and undiscovered sexual selection in this species. We found instead that the distribution of body size variation (weight, shell length) was similar between males and females of R. rectius, and mean sizes were not different between the sexes. However, we noted a male-biased sex ratio (~1:1.3) in our large sample of individuals. Many live scaphopods (and several dead shells) showed partial or complete boreholes drilled by predatory gastropods. Boreholes were observed on males and females in similar proportions. We collected scaphopods along with multiple individuals of one likely scaphopod predator, the small moon snail Euspira pallida, and in the lab we observed successful attacks by moon snails on tusk shells

Non-natives: 141 scientists object [Letter]

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