Battle of the Biotics: Assessing the Impacts of Biotic and Abiotic Factors on Amphibian Chytrid Fungus Survival
Location
SU-003
Start Date
28-4-2023 9:20 AM
Department
Biology
Abstract
Batrachochytrium dendrobatidis, the amphibian chytrid fungus known as Bd, is one of the greatest threats facing amphibians. Chytrid has been the leading cause of frog deaths in the rainforests of Australia and Panama since it was first described in 1997. The disease associated with chytrid, chytridiomycosis, is fatal in post-metamorphic frogs when zoospores are released into the waterways which infect other amphibians. The chytrid fungus is an amphibian generalist, meaning it is not limited to only frog deaths, but can also be linked to other amphibian deaths such as salamanders and newts. In this study, we aim to understand how environmental factors impact zoospore survival, and how climate change may be a driving force behind increased chytrid spread. Abiotic factors related to global warming such as rising temperatures and CO2 were examined first. To test temperature, zoospores were incubated from 17-35 degrees Celsius for 12 days, and live zoospore counts were assessed at days 4, 8, and 12. Zoospores thrived in this temperature range, with modest inhibition induced at 33 degrees Celsius, suggesting that as climate change warms environments, zoospores can survive and potentially infect a broader range of hosts. We also tested the effects of an anaerobic environment on the free-swimming zoospores since this stage has to encyst in the amphibian’s skin to continue its lifecycle. We found that a CO2 rich environment does not inhibit the free-swimming zoospores but enhances survival. We also tested four different soil Bacillus species that have some antifungal properties to determine if their enhancement could counter abiotic enhancement effects. Each Bacillus species was cultured in BHI broth and chytrid zoospores were directly exposed to the conditioned supernatant to yield qualitative and quantitative impacts on zoospore survival. Bacillus thuringiensis was the most consistent inhibitor in preliminary testing suggesting that this specific soil bacteria may provide a protective effect to amphibians. Together, these findings suggest that climate change, its causes and effects, are increasing zoospore survival, but may also enhance inhibitors in some environments. Future work consists of exposing zoospores to common fertilizer components as well as combining abiotic factors.
Faculty Sponsor
Emily Rumschlag-Booms, Northeastern Illinois University
Battle of the Biotics: Assessing the Impacts of Biotic and Abiotic Factors on Amphibian Chytrid Fungus Survival
SU-003
Batrachochytrium dendrobatidis, the amphibian chytrid fungus known as Bd, is one of the greatest threats facing amphibians. Chytrid has been the leading cause of frog deaths in the rainforests of Australia and Panama since it was first described in 1997. The disease associated with chytrid, chytridiomycosis, is fatal in post-metamorphic frogs when zoospores are released into the waterways which infect other amphibians. The chytrid fungus is an amphibian generalist, meaning it is not limited to only frog deaths, but can also be linked to other amphibian deaths such as salamanders and newts. In this study, we aim to understand how environmental factors impact zoospore survival, and how climate change may be a driving force behind increased chytrid spread. Abiotic factors related to global warming such as rising temperatures and CO2 were examined first. To test temperature, zoospores were incubated from 17-35 degrees Celsius for 12 days, and live zoospore counts were assessed at days 4, 8, and 12. Zoospores thrived in this temperature range, with modest inhibition induced at 33 degrees Celsius, suggesting that as climate change warms environments, zoospores can survive and potentially infect a broader range of hosts. We also tested the effects of an anaerobic environment on the free-swimming zoospores since this stage has to encyst in the amphibian’s skin to continue its lifecycle. We found that a CO2 rich environment does not inhibit the free-swimming zoospores but enhances survival. We also tested four different soil Bacillus species that have some antifungal properties to determine if their enhancement could counter abiotic enhancement effects. Each Bacillus species was cultured in BHI broth and chytrid zoospores were directly exposed to the conditioned supernatant to yield qualitative and quantitative impacts on zoospore survival. Bacillus thuringiensis was the most consistent inhibitor in preliminary testing suggesting that this specific soil bacteria may provide a protective effect to amphibians. Together, these findings suggest that climate change, its causes and effects, are increasing zoospore survival, but may also enhance inhibitors in some environments. Future work consists of exposing zoospores to common fertilizer components as well as combining abiotic factors.