Amphibian commerce as a likely source of pathogen pollution

Area of Science:

• Amphibian disease ecology
• Wildlife trade impacts
• Conservation biology

Background:

• Global wildlife trade facilitates the spread of non-native species and pathogens.
• Emerging infectious diseases, like chytridiomycosis (Bd) and ranaviral disease, are linked to amphibian declines worldwide.
• The commercial amphibian trade may be a significant source of pathogen pollution.

Purpose of the Study:

• To screen tiger salamanders in the bait trade for ranaviruses and Batrachochytrium dendrobatidis (Bd).
• To determine the geographic movement of these amphibians and their associated pathogens through commercial trade.
• To assess the role of anglers and bait shops in the release of infected tiger salamanders into the wild.

Main Methods:

• Polymerase chain reaction (PCR) was used to detect ranaviruses and Bd in tiger salamanders.
• Oral reports from bait shops and ranavirus DNA sequences were used to track pathogen movement.
• Surveys of anglers and bait shops were conducted to understand release practices.

Main Results:

• Ranaviruses were detected in tiger salamanders across Arizona, Colorado, and New Mexico.
• Batrachochytrium dendrobatidis (Bd) was detected in Arizona bait shops.
• Ranaviruses spread geographically via the bait trade, with wild-collected salamanders moving east to west and north to south.
• A significant percentage of anglers released tiger salamanders into fishing waters (26-67%).
• A small percentage of bait shops released tiger salamanders back into the wild (4%).

Conclusions:

• The tiger salamander bait trade in the western U.S. facilitates the anthropogenic movement of amphibians and their pathogens.
• Unregulated commercial trade poses a substantial risk for the spread of infectious diseases impacting wild amphibian populations.
• This trade system serves as a model for understanding the ecological consequences of moving wildlife and associated pathogens.