Article Review: Profiling a possible rapid extinction event in a long-lived species

It is no secret that there are detrimental effects on wildlife and ecosystems as a result of climate change; however, we are just beginning to understand just how expansive these consequences are. A study was conducted by Spencer et al. to examine the cause of rapid extinction rates of the Belligner River snapping turtle, Myuchelys georgesi in the summers of 2014 and 2015 in north-eastern New South Wales, Australia. It was concluded that the population was rapidly reduced because of disease caused by unknown pathogens. In February 2015 it was reported that around 432 turtles were found either dead or possessed symptoms of the disease on the banks of the Bellinger River. Symptoms of the disease included slow movement, lethargic behavior, or potential blindness due to the inflammation of the eyes and surrounding area. This “mystery disease” decreased this native population at an alarming rate. 

In this study, researchers compiled any evidence of this species-specific disease from scientific and public reports, used historical data to evaluate the overall health of the species population and in individuals, and overall analyzed the changes of environmental factors: temperature, rainfall, and river levels. Scientist were able to compare size structure of the historical population, using data from a systematic survey conducted in 2007, with the affected population and the population one year after the out-break in 2016 using histograms. From the data collected in 2007 they were able to identify 18 individuals that were affected in the 2015 out-break. The analyses showed that overall grown adult population of the Myuchelys georgesi were severely impacted from 2007 vs. 2015 by the disease, but not juveniles. The turtles that were rescued and relocated did not display any symptoms of disease the following year. It was suspected that a pathogen may have infected an area of their diet that is inaccessible to juveniles. The environmental data collected showed that from 2012 to 2015 water levels in the area dropped 30% in 2014. Examining the data also showed that there was an increase in overall temperature showing that in 2014 was almost doubled since 2010.

This raises future concerns for bigger potential impacts of pathogens and diseases on freshwater ecosystems that so many turtle species call home. As carbon dioxide atmospheric levels rapidly increase we are just beginning to scratch the surface of the effects of warmer climates. Pathogens thrive in warm climates and as water evaporation rates increase, leaving less water in aquatic ponds, it leaves more of an opportunity for pathogens, diseases, viruses, and parasites to thrive resulting in rapid extinction. It is important to monitor populations and implement back-up management strategies to save native turtle population’s if/when an event like this would to reoccur.

Spencer, R.-J., Van Dyke, J., Petrov, K., Ferronato, B., McDougall, F., Austin, M., Keitel, C., Georges, A. (2018). Profiling a possible rapid extinction event in a long-lived species. Biological Conservation, 221, 190–197. https://doi-org.nuncio.cofc.edu/10.1016/j.biocon.2018.03.009

https://www-sciencedirect-com.nuncio.cofc.edu/science/article/pii/S0006320717305335