Historic occurrence of the amphibian chytrid ­fungus Batrachochytrium dendrobatidis in ­hellbender Cryptobranchus alleganiensis ­populations from Missouri

Abstract

The pathogenic fungus Batrachochytrium dendrobatidis (Bd) was recently detected in Missouri hellbender Cryptobranchus alleganiensis populations that have declined precipitously for unclear reasons. The objective of this study was to determine whether Bd occurred historically in Missouri hellbender populations or is a relatively novel occurrence. Epidermal tissue was removed from 216 archived hellbenders collected from 7 Missouri streams between 1896 and 1994. Histological techniques and an immunoperoxidase stain were used to confirm historic occurrence of Bd infection in hellbenders from the North Fork of the White (1969, 1973, 1975), Meramec (1975Meramec ( , 1986, Big Piney (1986), and Current rivers (1988). Bd was not detected in hellbenders from the Niangua, Gasconade or Eleven Point rivers. The study detected no evidence for endemism of Bd in Missouri hellbender populations prior to 1969, despite the fact that nearly one third of the hellbenders sampled were collected earlier. Our findings are consistent with the hypothesis that Bd is a non-endemic pathogen in North America that was introduced in the second half of the twentieth century.

Why Does Amphibian Chytrid (Batrachochytrium dendrobatidis) Not Occur Everywhere? An Exploratory Study in Missouri Ponds

“…Thus, although broad predictions can be made about the potential geographic distribution of Bd based on its known distribution, [12], [13], relatively little is known about why Bd occurs where it does at a finer scale, for example among habitats or sites within a region (but see[14], [15]). This is an important consideration because while Bd is essentially omnipresent in some regions [9], [10], in others (e.g., parts of Africa, the United States, and Asia) Bd occurs only in a subset of apparently suitable sites, i.e., aquatic habitats with populations of amphibians [16]–[20].…”

Evidence of ectoparasite-induced endocrine disruption in an imperiled giant salamander, the eastern hellbender (Cryptobranchus alleganiensis)

“…Recently, the Ozark subspecies (Cryptobranchus alleganiensis bishop Grobman) was offered protection as a federally endangered species (Federal Register, 2010). The eastern subspecies (Cryptobranchus alleganiensis alleganiensis Daudin) is currently being considered for this designation because they suffer from similar factors to Ozark hellbenders, including habitat degradation, parasites and disease, and degraded water quality (Mayasich et al, 2003;Hiler et al, 2005;Briggler et al, 2007a,b;Bodinof et al, 2011Bodinof et al, , 2012Hopkins and DuRant, 2011;Davis and Hopkins, 2013). However, despite their dramatic population declines we know little about the basic physiology of hellbenders in the wild (but see Hopkins and DuRant, 2011;Solís et al, 2007), and nothing about how parasite infection influences their physiology.…”

Relating resource use to body condition and survival of Ozark hellbenders Cryptobranchus alleganiensis bishopi

“…Examples of extrinsic factors suggested to potentially affect Ozark hellbender populations include impoundments affecting flow and temperature of water, sedimentation, water contamination, predation, disease, and disturbance (Briggler et al 2007, Solís et al 2007, Bodinof et al 2011, Gould 2011. Perhaps measures of energetics and extrinsic factors can be simultaneously related to an accurate index of fitness such as lifetime reproductive success to gain a clearer understanding of causes of variation in individual hellbender biological outcome.…”

“…Bodinof et al (2012b) tested each hellbender for presence of the pathogenic amphibian chytrid fungus Batracho chy trium dendrobatidis before release and during any recaptures. Bodinof et al (2011) investigated infection of the amphibian chytrid fungus as a cause of hellbender decline, but we did not use this as a predictor variable because only 4 individuals used in modeling tested positive and only one of these died. Additionally, 1 infected individual improved body condition, 1 declined, and 2 had little change.…”