The efficacy of hydrogen peroxide agalnst the common salmon louse Lepeophthejrus salmonis, and ~t s toxicity to Atlantic (Salmo salar) and chinook (Oncorhynchus tsharuytscha) salmon, were investigated under laboratory cond~tions. Twenty mlnute bath treatments of 1.5 g 1.' hydrogen peroxide at 11 "C effectively dislodged approximately 80 "Aj of the preadult and adult stages of L. salmonis, but had no significant effect on the Intensity of infection with the attached chalimus stages. More than 96 % of the chalimus larvae and 84 % of the preadults and adults recovered after a 20 min hydrogen peroxide treatment at concentrations of 1.0 to 2.0 g I-' at 11 'C. Atlantic salmon were less sensitive to hydrogen peroxide than chinook salmon. The toxicity to both salmon specles increased wlth increasing water temperatures, concentrat~on, and exposure time. Histological sections of gills revealed extensive epithelia1 liftlng and necrosis in those chinook and Atlantic salmon that exper~enced acute t o x~c~t y .

Climate change threatens human health, but there remains a lack of evidence on the economic toll of climate‐sensitive public health impacts. We characterize human mortality and morbidity costs associated with 10 climate‐sensitive case study events spanning 11 US states in 2012: wildfires in Colorado and Washington, ozone air pollution in Nevada, extreme heat in Wisconsin, infectious disease outbreaks of tick‐borne Lyme disease in Michigan and mosquito‐borne West Nile virus in Texas, extreme weather in Ohio, impacts of Hurricane Sandy in New Jersey and New York, allergenic oak pollen in North Carolina, and harmful algal blooms on the Florida coast. Applying a consistent economic valuation approach to published studies and state estimates, we estimate total health‐related costs from 917 deaths, 20,568 hospitalizations, and 17,857 emergency department visits of $10.0 billion in 2018 dollars, with a sensitivity range of $2.7–24.6 billion. Our estimates indicate that the financial burden of deaths, hospitalizations, emergency department visits, and associated medical care is a key dimension of the overall economic impact of climate‐sensitive events. We found that mortality costs (i.e., the value of a statistical life) of $8.4 billion exceeded morbidity costs and lost wages ($1.6 billion combined). By better characterizing health damages in economic terms, this work helps to shed light on the burden climate‐sensitive events already place on U.S. public health each year. In doing so, we provide a conceptual framework for broader estimation of climate‐sensitive health‐related costs. The high health‐related costs associated with climate‐sensitive events highlight the importance of actions to mitigate climate change and adapt to its unavoidable impacts.

An understanding of the mechanisms of seed dispersal is critical to effectively managing populations of non-native plants. We investigated whether introduced bison on Santa Catalina Island, California, have the potential to spread non-native plants through the shedding of clumps of seed-laden hair and/or ingesting and later excreting seeds. We collected clumps of hair shaved from bison during a roundup and dislodged by wallowing activity. Greenhouse and field trials were used to test for seed viability and persistence of hair clumps in wallows. In addition to trials with bison hair, we collected samples of bison dung and tested for seed germination in a greenhouse. The majority of seeds extracted from bison hair clumps were of non-native forbs. There was a significant positive relationship between the size of hair clumps and the number of seeds extracted from the clumps, suggesting that managing the introduced bison population at a lower level will help minimize the spread of non-native plants by the species. Seeds of non-native plants were capable of germinating under conditions similar to those on Santa Catalina Island. Clumps of bison hair persisted in wallows, but did not remain intact and lost nearly 40% of their original mass. The number of germinable seeds contained in bison dung was low: 18 seeds germinated from 6 of 18 dung samples. Introduced bison appear to facilitate the dispersal of non-native plants over native plants on Santa Catalina Island. Our study suggests that a comprehensive strategy to control non-native plants must involve the management of the animal agents of plant dispersal.

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