No abstract

Due to concerns that wildlife may be attracted to Stormwater detention ponds and would be exposed to contaminants accumulating in these ponds, a field study of 15 Stormwater ponds and one natural wetland in Guelph and the Greater Toronto Area, Ontario, was performed in 1997 and 1998. At 9 of 16 sites, copper levels in water exceeded the Canadian Water Quality Guidelines (CWQGs) for the protection of aquatic life. Canadian Water Quality Guidelines were also exceeded by average water concentrations for lead at four sites, for zinc at three sites, for chromium at seven sites, and turbidity at ten sites. At the natural wetland, only turbidity levels exceeded the CWQGs. Sediments from all ponds contained concentrations of at least one contaminant that exceeded the “lowest effects level” (LED of the Guidelines for the Protection and Management of Aquatic Sediment in Ontario. Stormwater pond sediments contained concentrations exceeding provincial sediment quality guidelines at the LEL for polychlorinated biphenyls (PCBs), gamma-hexachlorocyclohexane (g-bhc), total Kjeldahl nitrogen (TKN) and total phosphorus (TP), turbidity, oil and grease, total PAHs, chromium, zinc, cadmium, copper, lead, nickel and arsenic. Concentrations of g-bhc, TKN, TP, cadmium, copper, lead, zinc and arsenic in the sediment of the natural wetland also exceeded the LEL. Sediments at one site exceeded the provincial guideline at the severe effect level for chromium. Concentrations of lead, zinc, cadmium and total PAHs in sediments were correlated with the age of the ponds. Concentrations of organochlorine pesticides and PCBs were low (<0.08 µg/g wet weight) in pump-kinseed (Lepomis gibbosus) collected from two ponds in Guelph. Red-winged blackbird [Agelaius phoeniceus) eggs from two ponds in Toronto contained up to 1130 ng/g pp’DDE and up to 670 ng/g total PCBs. Those concentrations were much higher than in a reference site, but an order of magnitude below concentrations associated with health effects in songbirds. Among four Stormwater ponds and one natural wetland in Guelph, there was statistically lower hatching success of northern leopard frogs (Rana pipiens) eggs, and larvae took longer to metamorphose into frogs at two Stormwater ponds. Statistically fewer tadpoles survived to metamorphosis at one Stormwater pond. We conclude that Stormwater ponds do not offer clean ecosystems for wildlife and the monitoring of contamination and its effects within Stormwater ponds is necessary.

Emerging infectious diseases (EIDs) are typically characterized by novelty (recent detection) and by increasing incidence, distribution, and/or pathogenicity. Ophidiomycosis, also called snake fungal disease, is caused by the fungus Ophidiomyces ophidiicola (formerly “ophiodiicola”). Ophidiomycosis has been characterized as an EID and as a potential threat to populations of Nearctic snakes, sparking over a decade of targeted research. However, the severity of this threat is unclear. We reviewed the available literature to quantify incidence and effects of ophidiomycosis in Nearctic snakes, and to evaluate whether the evidence supports the ongoing characterization of ophidiomycosis as an EID. Data from Canada remain scarce, so we supplemented the literature review with surveys for O. ophidiicola in the Canadian Great Lakes region. Peer-reviewed reports of clinical signs consistent with ophidiomycosis in free-ranging, Nearctic snakes date back to at least 1998, and retrospective molecular testing of samples extend the earliest confirmed record to 1986. Diagnostic criteria varied among publications (n = 33), confounding quantitative comparisons. Ophidiomycosis was diagnosed or suspected in 36/121 captive snakes and was fatal in over half of cases (66.7%). This result may implicate captivity-related stress as a risk factor for mortality from ophidiomycosis, but could also reflect reporting bias (i.e., infections are more likely to be detected in captive snakes, and severe cases are more likely to be reported). In contrast, ophidiomycosis was diagnosed or suspected in 441/2,384 free-ranging snakes, with mortality observed in 43 (9.8 %). Ophidiomycosis was only speculatively linked to population declines, and we found no evidence that the prevalence of the pathogen or disease increased over the past decade of targeted research. Supplemental surveys and molecular (qPCR) testing in Ontario, Canada detected O. ophidiicola on 76 of 657 free-ranging snakes sampled across ~136,000 km2. The pathogen was detected at most sites despite limited and haphazard sampling. No large-scale mortality was observed. Current evidence supports previous suggestions that the pathogen is a widespread, previously unrecognized endemic, rather than a novel pathogen. Ophidiomycosis may not pose an imminent threat to Nearctic snakes, but further research should investigate potential sublethal effects of ophidiomycosis such as altered reproductive success that could impact population growth, and explore whether shifting environmental conditions may alter host susceptibility.

Ophidiomycosis (snake fungal disease) is caused by the fungus Ophidiomyces ophiodiicola. As ophidiomycosis is difficult to study in free-ranging snakes, a reliable experimental model is needed to investigate transmission, pathogenesis, morbidity, and mortality, and the effects of brumation and temperature on disease development. Our objective was to develop such a model via subcutaneous injection of O. ophiodiicola conidia in red cornsnakes ( Pantherophis guttatus). The model was used to evaluate transmission and the effects of brumation and temperature in co-housed inoculated and noninoculated snakes. All 23 inoculated snakes developed lesions consistent with ophidiomycosis, including heterophilic and granulomatous dermatitis, cellulitis, and myositis, and embolic fungal granulomas throughout the liver and the coelomic connective tissue in 21/23 (91%). In the inoculated snakes, 21% of skin swabs, 37% of exuvia, and all liver samples tested positive by qPCR (quantitative polymerase chain reaction) for O. ophiodiicola. A post brumation skin swab from 1/12 noninoculated snakes that brumated in contact with inoculated snakes tested positive by qPCR, suggesting possible contact transmission. That snake had microscopic skin lesions consistent with ophidiomycosis, but no visible fungal elements. Of the 23 inoculated snakes, 20 (87%) died over the 70-day experiment, with ophidiomycosis considered the primary cause of death; 12 (52%) of the inoculated snakes died during brumation. Overall, this experimental model of ophidiomycosis reproduced skin lesions analogous to those of many natural cases, and internal lesions similar to the most severe natural cases. The study provides tentative experimental evidence for horizontal transmission in brumation, and offers a tool for future studies of this widespread snake disease.