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Population declines of a long-lived salamander: a 20+-year study of hellbenders, Cryptobranchus alleganiensis

Population declines of a long-lived salamander: a 20+-year study of hellbenders, Cryptobranchus alleganiensis,10.1016/S0006-3207(02)00136-2,Biological

Population declines of a long-lived salamander: a 20+-year study of hellbenders, Cryptobranchus alleganiensis   (Citations: 26)
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Accurate assessment of whether long-lived species are stable or declining is challenging. Life history characteristics such as delayed maturity result in relatively slow population responses to perturbations, so data should be collected across a relatively long time span. Because differential effects on age classes can be important, studies should also examine potential changes in the population's age structure. Moreover, multiple populations should be studied to indicate whether changes are regional or are restricted to local populations. We incorporated all three factors (long duration, multiple populations, age structure data) into our study of the conservation status of a long-lived aquatic salamander, the hellbender, Cryptobranchus alleganiensis. Over the 20+ years of this study, populations of hellbenders declined by an average of about 77%. This decline was characterized by a shift in size (age) structure, with a disproportionate decrease in numbers of young individuals. The change in density and age structure was consistent for populations in five rivers and for two subspecies (C. a. alleganiensis and C. a. bishopi), indicating that the decline is not restricted to one or two local populations. For the population with the most extensive data, the decline had clearly begun by the 1980s and there was a significant decrease in body condition over the period of the study. It is not known whether population declines for hellbenders have a single cause or whether each population has experienced independent declines.
Journal: Biological Conservation - BIOL CONSERV , vol. 109, no. 1, pp. 151-156, 2003
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    • ...All are obligately aquatic and are experiencing population declines due to habitat adulteration and loss, environmental contamination, and illegal harvest for consumption or the exotic pet trade (Trauth et al. 1992; Wheeler et al. 2003; Wang et al. 2004)...
    • ...The Ozark hellbender attains an average length of 29‐57 cm (Dundee and Dundee 1965), while the eastern hellbender may measure 45‐60 cm (Wheeler et al. 2003)...
    • ...Surveys of five Missouri Rivers have shown that juvenile recruitment is decreasing and populations of both hellbender subspecies have declined by 70‐80% in the last 20 years (Wheeler et al. 2003)...
    • ...Siltation (Trauth et al. 1992; Wheeler et al. 2003), habitat alterations (Wheeler et al. 2003), collection for scientific study (Nickerson and Briggler 2007), and the possible spread of pathogens such as amphibian chytrid fungus Batrachochytrium dendrobatidis (Briggler et al. 2007a, 2008) have all been implicated in the decline of this...
    • ...Siltation (Trauth et al. 1992; Wheeler et al. 2003), habitat alterations (Wheeler et al. 2003), collection for scientific study (Nickerson and Briggler 2007), and the possible spread of pathogens such as amphibian chytrid fungus Batrachochytrium dendrobatidis (Briggler et al. 2007a, 2008) have all been implicated in the decline of this...

    Rachel S. Crowhurstet al. Genetic relationships of hellbenders in the Ozark highlands of Missour...

    • ...Recent studies have concluded that many populations of both subspecies are experiencing population declines (Williams et al. 1981; Wheeler et al. 2003, Routman, personal observation of the Meramec River population), and the US Fish and Wildlife Service (USFWS) is considering listing both subspecies as endangered under the Endangered Species Act (Amy Salveter, USFWS, pers...

    Maria Tonioneet al. Microsatellite analysis supports mitochondrial phylogeography of the h...

    • ...Many populations of C. a. alleganiensis are also smaller than in the recent past and face similar threats (Wheeler et al. 2003)...

    Stephen J. Sabatinoet al. Phylogeography and conservation genetics of the hellbender salamander ...

    • ...Although the actual cause of the hellbender decline was determined to be unknown, the authors postulate that habitat degradation (i.e., siltation and eutrophication) and chemical pollution were likely, at least, partly responsible (Wheeler et al., 2003)...

    Michael S. Bankaet al. Population decline of northern dusky salamanders at Acadia National Pa...

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