Authors: M P Stockwell J Clulow M J Mahony
Publish Date: 2014/11/23
Volume: 177, Issue: 3, Pages: 901-910
Abstract
With the incidence of emerging infectious diseases on the rise it is becoming increasingly important to identify refuge areas that protect hosts from pathogens and therefore prevent population declines For the chytrid fungus Batrachochytrium dendrobatidis temperature and humidity refuge areas for amphibian hosts exist but are difficult to manipulate Other environmental features that may affect the outcome of infection include water quality drying regimes abundance of alternate hosts and isolation from other hosts We identified relationships between water bodies with these features and infection levels in the freeliving hosts inhabiting them Where significant relationships were identified we used a series of controlled experiments to test for causation Infection loads were negatively correlated with the salt concentration of the aquatic habitat and the degree of water level fluctuation and positively correlated with fish abundance However only the relationship with salt was confirmed experimentally Freeliving hosts inhabiting water bodies with mean salinities of up to 35 ppt had lower infection loads than those exposed to less salt The experiment confirmed that exposure to sodium chloride concentrations 2 ppt significantly reduced host infection loads compared to no exposure 0 ppt These results suggest that the exposure of amphibians to salt concentrations found naturally in lentic habitats may be responsible for the persistence of some susceptible species in the presence of B dendrobatidis By manipulating the salinity of water bodies it may be possible to create refuges for declining amphibians thus allowing them to be reintroduced to their former rangesWe would like to acknowledge the Australian Animal Health Laboratory for training in realtime PCR and providing chytrid isolates We thank Evan Pickett Riona Tindal Dale Bond and Tegan Hunter for assistance with data collection This work was funded by the Port Waratah Coal Service through the Kooragang Wetland Rehabilitation Project
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