https://www.mde.maryland.gov/programs/Marylander/Documents/Canedo-Arguelles_13_SalinisationOfRivers_UrgentEcologicalIssue.pdf

Salinisation of rivers: An urgent ecological issue

Non-typhoidal Salmonella represents an important human and animal pathogen world-wide. Most human salmonellosis cases are foodborne, but each year infections are also acquired through direct or indirect animal contact in homes, veterinary clinics, zoological gardens, farm environments or other public, professional or private settings. Clinically affected animals may exhibit a higher prevalence of shedding than apparently healthy animals, but both can shed Salmonella over long periods of time. In addition, environmental contamination and indirect transmission through contaminated food and water may complicate control efforts. The public health risk varies by animal species, age group, husbandry practice and health status, and certain human subpopulations are at a heightened risk of infection due to biological or behavioral risk factors. Some serotypes such as Salmonella Dublin are adapted to individual host species, while others, for instance Salmonella Typhimurium, readily infect a broad range of host species, but the potential implications for human health are currently unclear. Basic hygiene practices and the implementation of scientifically based management strategies can efficiently mitigate the risks associated with animal contacts. However, the general public is frequently unaware of the specific disease risks involved, and high-risk behaviors are common. Here we describe the epidemiology and serotype distribution of Salmonella in a variety of host species. In addition, we review our current understanding of the public health risks associated with different types of contacts between humans and animals in public, professional or private settings, and, where appropriate, discuss potential risk mitigation strategies.

/pdf/animal-contact-as-a-source-of-human-non-typhoidal-210w74a7sb.pdf

Animal contact as a source of human non-typhoidal salmonellosis

Salmonella outbreaks from contaminated water and nonanimal foods (e.g., produce) are increasingly reported. To address the environment as a potential source of pathogenic Salmonella, we investigated levels of salmonellae and the geographic and temporal variation of Salmonella serotypes from surface waters in a region of Georgia (United States) with a history of high salmonellosis case rates. Monthly water samples were collected from six stations in the Little River (Upper Suwannee Basin) for 12 months (April 2005 to April 2006). Salmonellae were enumerated using a three-step most-probable-number (MPN) assay. Salmonellae were detected in 57 of the 72 water samples collected (79.2%). Monthly Salmonella densities ranged from an MPN of 2.5 liter−1 in April 2005 to 36.3 liter−1 in August 2005; concentrations were significantly higher in the summer months compared to other seasons (P < 0.05). Concentrations were not significantly different between stations. Levels of salmonellae were correlated with average daily watershed rainfall for the 1 and 2 days preceding each sample collection (r = 0.77 and 0.68, respectively; P < 0.005). Additionally, water temperature was also positively associated with total Salmonella levels (r = 0.44; P < 0.05). In total, 13 S. enterica serotypes were identified among 197 Salmonella isolates. Eighty (40.6%) were identified as S. enterica subsp. arizonae. Muenchen and Rubislaw were the most frequently identified serotypes of the remaining 117 isolates (28 and 26 isolates, respectively). Serotype diversity peaked in the summer, with 9 serotypes observed in August compared to only one serotype (S. enterica subsp. arizonae) observed in April (2005 and 2006) (P < 0.05). Furthermore, all samples collected in August (6/6) contained multiple serotypes (two to five per sample). The results of this study suggest that Salmonella abundance and diversity in the environment vary temporally and are strongly influenced by seasonal precipitation and water temperature.

Distribution, Diversity, and Seasonality of Waterborne Salmonellae in a Rural Watershed

Degradation and dispersion limit environmental DNA detection of rare amphibians in wetlands: Increasing efficacy of sampling designs

Amphibians are well known as osmotically sensitive organisms due to their highly permeable skin and eggs and, as such, biologists have mostly discounted their presence in saline environments. Yet, from the 1800s to the present day, scientists have repeatedly found amphibians living and breeding in a variety of saline coastal and inland habitats. Despite this plethora of observations, their presence in these habitats is still mostly ignored, and the last (and only) complete literature review documenting amphibians in brackish and saline habitats was completed over 50 yr ago. Here we provide a review of the literature of amphibians in saline waters and present data on 144 species, in 28 families, on every continent except Antarctica. In doing so, we make the case that salt tolerance in amphibians may not be as rare as generally assumed. Through classifying habitats and studies, we conclude that the abilities of dozens of species to locally adapt to coastal and inland saline habitats have been exte...

https://bioone.org/journals/herpetological-monographs/volume-29/issue-1/HERPMONOGRAPHS-D-14-00006/Occurrence-of-Amphibians-in-Saline-Habitats--A-Review-and/10.1655/HERPMONOGRAPHS-D-14-00006.pdf

Occurrence of Amphibians in Saline Habitats: A Review and Evolutionary Perspective

Exposure to altered conductivity can negatively impact many freshwater system inhabitants, including bacteria, plants, invertebrates, and vertebrates. Several studies have shown increased conductivity to affect amphibian behavior and ecology. Comparatively fewer studies have taken a physiological approach to understanding the effects of altered conductivity in amphibians. This study used laboratory experiments to assess conductivity effects on stress hormone (corticosterone) levels in Jefferson Salamander (Ambystoma jeffersonianum), Wood Frog (Rana sylvatica), and Gray Treefrog (Hyla versicolor) larvae. Prey consumption (only in A. jeffersonianum) and survival (in all species) also was examined after exposure to increased conductivity (0, 2,000, 4,000, and 8,000 ppb). There was a significant positive effect of increased conductivity exposure on baseline corticosterone levels in A. jeffersonianum after 1-week exposure. Exposure to increased conductivity did not influence baseline corticosterone le...

https://bioone.org/journals/journal-of-herpetology/volume-45/issue-2/09-211.1/Increased-Conductivity-Affects-Corticosterone-Levels-and-Prey-Consumption-in-Larval/10.1670/09-211.1.pdf

Increased Conductivity Affects Corticosterone Levels and Prey Consumption in Larval Amphibians

Physiological tolerances play a key role in determining species distributions and abundance across a landscape, and understanding these tolerances can therefore be useful in predicting future changes in species distributions that might occur. Vertebrates possess several highly conserved physiological mechanisms for coping with environmental stressors, including the hormonal stress response that involves an endocrine cascade resulting in the increased production of glucocorticoids. We examined the function of this endocrine axis by assessing both baseline and acute stress–induced concentrations of corticosterone in larvae from eight natural breeding populations of Jefferson’s salamander Ambystoma jeffersonianum. We surveyed individuals from each pond and also examined a variety of environmental pond parameters. We found that baseline and stress-induced corticosterone concentrations differed significantly among ponds. Population-level baseline corticosterone concentrations were negatively related to...

/pdf/pond-acidification-may-explain-differences-in-corticosterone-1gqb4ho8cq.pdf

Pond acidification may explain differences in corticosterone among salamander populations.

This study examined possible effects of several abiotic parameters on breeding-pool selection of Ambystoma jeffersonianum (Jefferson Salamander), A. maculatum (Spotted Salamander), A. opacum (Marbled Salamander), and Notophthalmus viridescens (Red-spotted Newt). Twenty-four ephemeral pools and permanent ponds, all adjacent to a logging road, were observed in south-central Pennsylvania in 2006. There was a significant correlative effect of distance from the logging road on breeding-site selection. Specifically, the distance from the road significantly differed between the breeding-sites of Jefferson Salamanders and Red-spotted Newts and between those of Marbled Salamander and Red-spotted Newts with both ambystomatid species breeding farther from the road than Red-spotted Newts. This study supports the idea that ambystomatid salamander breeding-site selection can be influenced by habitat disturbance, while generalist species are not as easily influenced.

Logging Road Effects on Breeding-site Selection in Notophthalmus viridescens (Red-spotted Newt) and Three Ambystomatid Salamanders in South-central Pennsylvania

Herpetofaunal Salmonella enterica serovars have not been fully examined in any U.S. region. Thirty-three Salmonella serovars were isolated from 156 samples from 34 species, all within Indiana County, Pennsylvania. Results suggest that herpetofaunas could potentially pose a threat to humans. Further understanding of Salmonella in herpetofaunas may prevent future human cases.

Salmonella serovars in the herpetofauna of Indiana County, Pennsylvania.

Studies of a few ‘‘model’’ amphibians continue to advance our mechanistic understanding of the endocrine control of larval amphibian development and metamorphosis, but there are few studies examining steroid profiles across species during larval amphibian development. We used censored regression analysis to address our primary objective, which was to examine baseline corticosterone level changes and responses to a standardized stressor throughout larval development in two amphibian species: one anuran (Wood Frogs, Rana sylvatica) and one caudate (Jefferson Salamanders, Ambystoma jeffersonianum). In addition, we looked at two additional factors that could influence the study of corticosterone during larval development, namely the rearing location of the animals (free-living, mesocosmheld, or laboratory-held) and for A. jeffersonianum, the method of induction of the stress response (ACTH injection or a confinement-agitation [CA] protocol). As has been documented for other anurans, baseline corticosterone content of R. sylvatica increased close to metamorphic climax in all rearing locations, although the absolute level varied with rearing location. Baseline corticosterone content of A. jeffersonianum increased gradually over development, and the increase in corticosterone content following CA mirrored the increase in baseline levels, although the absolute magnitude of the increase with CA varied based on rearing location. In larvae of A. jeffersonianum, both the CA method and ACTH injection significantly increased corticosterone content, with 30 min eliciting the maximum hormonal response level. Our results suggest that rearing location can influence corticosterone levels and the response to a standardized CA protocol, and that care should be taken in extrapolating results from laboratory studies to free-living amphibian populations.

https://bioone.org/journals/Copeia/volume-2011/issue-4/CP-09-180/Corticosterone-Level-Changes-throughout-Larval-Development-in-the-Amphibians-Rana/10.1643/CP-09-180.pdf

Corticosterone Level Changes throughout Larval Development in the Amphibians Rana sylvatica and Ambystoma jeffersonianum Reared under Laboratory, Mesocosm, or Free-living Conditions

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