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Bottlenose dolphins (Tursiops truncatus) are keystone and sentinel species in the world's oceans. We studied correlations between per- and polyfluoroalkyl substances (PFAS) and their stress axis. We investigated associations between plasma biomarkers of 12 different PFAS variants and three cortisol pools (total, bound, and free) in wild T. truncatus from estuarine waters of Charleston, South Carolina (n = 115) and Indian River Lagoon, Florida (n = 178) from 2003 to 2006, 2010-2013, and 2015. All PFAS and total cortisol levels for these dolphins were previously reported; bound cortisol levels and free cortisol calculations have not been previously reported. We tested null hypotheses that levels of each PFAS were not correlated with those of each cortisol pool. Free cortisol levels were lower when PFOS, PFOA, and PFHxS biomarker levels were higher, but free cortisol levels were higher when PFTriA was higher. Bound cortisol levels were higher when there were higher PFDA, PFDoDA, PFDS, PFTeA, and PFUnDA biomarkers. Total cortisol was higher when PFOA was lower, but total cortisol was higher when PFDA, PFDoDA, PFTeA, and PFTriA were higher. Additional analyses indicated sex and age trends, as well as heterogeneity of effects from the covariates carbon chain length and PFAS class. Although this is a cross-sectional observational study and, therefore, could reflect cortisol impacts on PFAS toxicokinetics, these correlations are suggestive that PFAS impacts the stress axis in T. truncatus. However, if PFAS do impact the stress axis of dolphins, it is specific to the chemical structure, and could affect the individual pools of cortisol differently. It is critical to conduct long-term studies on these dolphins and to compare them to populations that have no or little expose to PFAS.

Simple Summary: Toxoplasma gondii is considered one of the most successful parasites in the world, potentially infecting any vertebrates, including humans. Its complex life cycle encompasses many transmission pathways, which remain enigmatic in northern ecosystems. The aim of our study was to assess Canada lynx as potential reservoir of and sentinel for T. gondii by (1) using serological and molecular assays to detect T. gondii, (2) determining if lynx are definitive hosts for the parasite, and (3) identifying potential risk factors that may contribute to lynx exposure. For the first time, T. gondii DNA was found in tissue and feces of Canada lynx, indicating that they can be both intermediate and definitive hosts in northern regions. Our findings would help identify high-risk regions for infections in northern Canada, with lynx serving as indicator for potential human exposure of T. gondii. Toxoplasma gondii is a zoonotic parasite globally infecting a wide range of species, including humans. Felids are the only known hosts that can excrete environmentally resistant oocysts into ecosystems. In boreal regions, Canada lynx (Lynx canadensis) are sought by hunters primarily for their fur, and they are occasionally eaten. We examined carcasses salvaged from trappers from boreal regions of eastern (n = 97) and western (n = 357) Canada. We detected T. gondii antibodies in fluid from thawed heart tissue using an enzyme-linked immunosorbent assay, DNA in brain and heart via magnetic capture and real-time PCR assay, and presence of DNA in feces using a real-time PCR with melt curve analysis. We detected antibodies against T. gondii and DNA in tissues in 24% and 19% of lynx, respectively. One lynx was positive for DNA of T. gondii in feces, which could indicate intestinal infection and potential for shedding oocysts. Our results indicate that lynx may be a useful sentinel species for monitoring environmental circulation of T. gondii in northern boreal regions and may pose a risk for transmission to other wildlife and to people handling or consuming lynx. [ABSTRACT FROM AUTHOR]

Climate warming is causing asynchronies between animal phenology and environments. Mismatched traits, such as coat color change mismatched with snow, can decrease survival. However, coat change does not serve a singular adaptive benefit of camouflage, and alternate coat change functions may confer advantages that supersede mismatch costs. We found that mismatch reduced, rather than increased, autumn mortality risk of snowshoe hares in Yukon by 86.5% when mismatch occurred. We suggest that the increased coat insulation and lower metabolic rates of winter‐acclimatized hares confer energetic advantages to white mismatched hares that reduce their mortality risk. We found that white mismatched hares forage 17–77 min less per day than matched brown hares between 0°C and −10°C, thus lowering their predation risk and increasing survival. We found no effect of mismatch on spring mortality risk, during which mismatch occurred at warmer temperatures, suggesting a potential temperature limit at which the costs of conspicuousness outweigh energetic benefits. [ABSTRACT FROM AUTHOR]