Shelter Guarding Behavior of the Eastern Hellbender (Cryptobranchus alleganiensis alleganiensis) in North Carolina Streams

Unger, Shem D.; Jachowski, Catherine M. Bodinof; Diaz, Lauren; Williams, Lori A.

doi:10.1656/058.019.0411

Cited by 10 publications

(4 citation statements)

References 49 publications

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“…Both males and females exhibited lowest hematocrit in winter when and activity is generally minimal ( Bodinof et al , 2012 b ), and dissolved oxygen is at its highest due to low water temperature. Male hematocrit peaked between September and October, which aligns with spawning, brooding eggs and frequent aggressive interactions with conspecifics ( Unger et al , 2020 ). In contrast, female hematocrit peaked in April and remained stable over summer, which aligns with the period when females are presumably focused on acquiring energy to invest in oocyte development.…”

Section: Discussionmentioning

confidence: 99%

The habitat quality paradox: loss of riparian forest cover leads to decreased risk of parasitism and improved body condition in an imperiled amphibian

Bodinof Jachowski,

Alaasam,

Blumenthal

et al. 2024

Conservation Physiology

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Amphibian declines are a global phenomenon but responses of populations to specific threats are often context dependent and mediated by individual physiological condition. Habitat degradation due to reduced riparian forest cover and parasitism are two threats facing the hellbender salamander (Cryptobranchus alleganiensis), but their potential to interact in nature remains largely unexplored. We investigated associations between forest cover, parasitic infection and physiology of hellbenders to test the hypotheses that physiological condition responds to infection and/or habitat degradation. We sampled 17 stream reaches in southwest Virginia, USA, on a year-round basis from 2013 to 2016 and recorded 841 captures of 405 unique hellbenders. At each capture we documented prevalence of two blood-associated parasites (a leech and trypanosome) and quantified up to three physiological condition indices (body condition, hematocrit, white blood cell [WBC] differentials). We used generalized linear mixed models to describe spatiotemporal variation in parasitic infection and each condition index. In general, living in the most heavily forested stream reaches, where hellbender density was highest, was associated with the greatest risk of parasitism, elevated neutrophil-to-lymphocyte (N:L) ratios and eosinophils, slightly lower hematocrit and lower mean body condition in hellbenders. All condition indices fluctuated temporally in a manner consistent with seasonal variation in hellbender metabolic demands and breeding phenology and were associated with land use during at least part of the year. Paradoxically, relatively low levels of forest cover appeared to confer a potential advantage to individuals in the form of release from parasites and improved body condition. Despite improved body condition, individuals from less forested areas failed to exhibit fluctuating body condition in response to spawning, which was typical in hellbenders from more forested habitats. We postulate this lack of fluctuation could be due to reduced conspecific competition or reproductive investment and/or high rates of filial cannibalism in response to declining forest cover.

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Section: Discussionmentioning

confidence: 99%

The habitat quality paradox: loss of riparian forest cover leads to decreased risk of parasitism and improved body condition in an imperiled amphibian

Bodinof Jachowski,

Alaasam,

Blumenthal

et al. 2024

Conservation Physiology

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“…Additionally, climate change is predicted to cause increases in rainfall intensity (Madsen & Figdor, 2007) as well as droughts (Leeper et al, 2022), and these aspects of water availability are known to have direct and indirect negative effects on egg‐laying habitat quality and quantity (Kennedy et al, 2016; Lancaster et al, 2021; Peckarsky et al, 2000). These and similar habitats are vital to a multitude of other aquatic organisms that use specific rocks, or sediment sizes, for their reproductive habitat (salmon: Kondolf & Wolman, 1993, bluehead chub: Sabaj et al, 2000, salamanders: Unger et al, 2020) that, in some cases, have been the focus of restoration and conservation efforts (salmon: Barlaup et al, 2008, Madtom catfish: Cope et al, 2019, various fishes: Taylor et al, 2019, salamanders: Button et al, 2020). Better integration of the biotic and abiotic components of stream restoration will require collaborations among disciplines such as ecology, entomology, hydrology, geomorphology, and engineering so that diverse knowledge is more readily identified and incorporated into restoration theory and practice.…”

Section: Summary Of Future Research Needsmentioning

confidence: 99%

Facilitating the recovery of insect communities in restored streams by increasing oviposition habitat

Dilworth,

Taylor

2023

Ecological Applications

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Recruitment limitation is known to influence species abundances and distributions. Recognition of how and why it occurs both in natural and in designed environments could improve restoration. Aquatic insects, for instance, rarely reestablish in restored streams to levels comparable to reference streams even years after restoration. We experimentally increased oviposition habitat in five out of 10 restored streams in western North Carolina to test whether insect egg‐laying habitat was limiting insect populations in restored streams. A main goal was to test whether adding oviposition habitat in the form of rocks that partially protrude above the water surface could be used to increase the abundance and richness of stream insect eggs and larval insects in restored streams. Adding egg‐laying habitat enhanced several response variables (e.g., protruding rocks, number of eggs, egg masses, egg morphotype richness, and oviposition habitat stability) to levels similar to those found in reference streams. Following the addition of protruding rocks, egg mass abundance increased by 186% and richness by 77% in restored‐treated streams. Densities of larval insects that attached their eggs to protruding rocks showed an overall pattern consistent with treatment effects due to the combination of nonsignificant and significant increases of several taxa and not just one taxon. Our results indicate that these stream insect populations are limited by oviposition habitat and that adding egg‐laying habitat alleviated this component of recruitment limitation. However, the weaker larval response indicates that additional post‐recruitment factors, such as egg or larval mortality, may still be limiting a full recovery of larval insect abundances in these restored streams. This study shows the importance of integrating information from animal life histories, ecology, and geomorphology into restoration practices to improve the recovery of aquatic insects, which are commonly used to assess water quality and the biological efficacy of stream restoration.

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“…On the other hand, fighting with spines may be energy-efficient in harming the opponent and hence to some extent make the combat affordable for high levels of cutaneous respiration. Underwater combat with pointed weapons also occurs in breeding males of the hellbender salamander Cryptobranchus alleganiensis (biting) and probably the hairy frog Astylosternus robustus (claws), which are regarded to exhibit a high cutaneous respiration capacity aided by well-vascularized skin folds or projections, respectively [3,72,[78][79][80][81][82][83].…”

Section: Exclusive Skin Breathing and Metabolically Demanding Behaviorsmentioning

confidence: 99%

Male spiny frogs enter the underwater battlefield with loose skin exhibiting enhanced penetration of capillaries into the epidermis

Xu,

Dai,

Zheng

2023

Zoological Lett

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The skin has multiple functions, and capillaries can penetrate the epidermis to shorten the diffusion path while allowing maintenance of overall epidermal thickness for nonrespiratory roles. However, a method for quantifying the capillary penetration extent is lacking. Such a method may facilitate making comparisons and detecting associations, potentially making the extent a useful variable in biological studies. We quantified the extent as the ratio of the average minimum thickness of epidermis overlying each capillary to the average epidermal thickness along a skin section and then explored its performance in the Emei mustache toad, Leptobrachium boringii, a species in which breeding males with loose skin call and fight each other with maxillary spines underwater. The ratio showed informative associations with other variables, such as perfused capillary density. It displayed small intragroup variation and could be more sensitive than other variables in revealing structural differences in the skin. The ratio estimates were lowest and were correlated with epidermal and stratum compactum thicknesses in breeding males, i.e., a covariation but not reinforcement against stabbing, constituting early evidence consistent with the increased extensibility of loose skin conferring a defensive advantage during combat in amphibians. In addition, our results lead to the hypothesis that high hemoglobin density along subepidermal capillaries favors the maintenance of low blood partial oxygen pressure and hence increases cutaneous oxygen uptake. We also provide evidence supporting the new idea that the cooccurrence of loose skin and underwater calling found in some frogs can be explained by the latter benefiting from a large functional respiratory surface area. Awareness of the usefulness of the ratio may promote its application and the quantification of the penetration. Regarding exchange surface design, these findings for L. boringii imply a case in which looseness increases surface area as well as prevents damage.

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Shelter Guarding Behavior of the Eastern Hellbender (Cryptobranchus alleganiensis alleganiensis) in North Carolina Streams

Cited by 10 publications

References 49 publications

The habitat quality paradox: loss of riparian forest cover leads to decreased risk of parasitism and improved body condition in an imperiled amphibian

The habitat quality paradox: loss of riparian forest cover leads to decreased risk of parasitism and improved body condition in an imperiled amphibian

Facilitating the recovery of insect communities in restored streams by increasing oviposition habitat

Male spiny frogs enter the underwater battlefield with loose skin exhibiting enhanced penetration of capillaries into the epidermis

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