Rana Tadpole Survival Rate and Infection Load After Exposure to Batrachochytrium dendrobatidis in Combination With Various Salt Concentrations

Donovan, Tristen

Rana Tadpole Survival Rate and Infection Load After Exposure to Batrachochytrium dendrobatidis in Combination With Various Salt Concentrations

Persistent URL

https://dspace.allegheny.edu/handle/10456/56711

Author(s)

Donovan, Tristen

Date Issued

April 2023

Abstract

Populations of amphibians have been declining around the world and one of the main pathogens associated with these declines is Batrachochytrium dendrobatidis (Bd), which causes chytridiomycosis. Since its discovery, research has been focused on mitigating its effects, identifying where the fungus originated from, and why it causes high mortality rates in different regions. Interactions between Bd and stressors may be the cause of higher Bd mortality in different regions and in different populations of amphibians. This is because stressors usually increase pathogen virulence by weakening a host’s immune system. However, there are some scenarios where stressors help the host by weakening the pathogen more than the host or by boosting the host’s immune system in an indirect way. So the interactions of the stressor with both the pathogen and the host must be taken into consideration to determine if the infected is better or worse off after the stressor is introduced. Sodium chloride (NaCl) is a stressor of interest because of the negative effects it can have on amphibians and its known antifungal properties. NaCl is known to cause decreased growth rates and developmental abnormalities in amphibians. NaCl is the most common salt used for road maintenance and as such easily finds its way into waterways. This study looked into the impact of 0, 2, and 4 ppt NaCl concentrations on Bd infection load and survival rate of tadpoles from the family Ranidae. The ranid tadpoles were collected from Allegheny’s Bousson Forest and were separated into individual containers consisting of the 0, 2, and 4 ppt NaCl concentrations. The tadpoles were then exposed to Bd or a sham exposure. Survival was documented daily and after three weeks the tadpoles had swabs taken to test for Bd infection load. Only a single tadpole tested positive for Bd, so the effects of NaCl on tadpoles exposed to Bd were examined rather than the effects of NaCl on tadpoles infected with Bd or Bd infection load. Bd, alone or with any tested salt concentration, did not have an effect on tadpole mortality. Further research is still needed to determine the effects of NaCl on Rana tadpoles exposed to Bd and the effects of NaCl on Bd infection load in Rana tadpoles. The proposed study species for further research is Lithobates sylvaticus because they can be observed through their whole metamorphosis in a reasonable timeframe. Observing L. sylvaticus throughout metamorphosis will give a better understanding of the short-term and long-term effects of the combination of NaCl and Bd on frogs from the family Ranidae.

Major

Biology

First Reader(s)

Venesky, Matthew D.