Written Assignment #2Conservation Biology 320Conner Bradley 3/5/2015

Investigating the Ecological Impact of White-Nosed Syndrome

Introduction:

Wildlife diseases describe pathogens that infect free ranging wild animals. Wildlife diseases differ from other disease because wildlife diseases are found in populations of non-domesticated species. Wildlife disease are often the result of a parasitic relationship. These relationships are not limited to specific taxa, they infect populations of all types of species, vertebrates, invertebrates, plants. Additionally, wildlife diseases are not defined by any specific group of organisms. All of the following groups are responsible for wildlife diseases: prions, virus, bacteria, fungi, protozoans, and more. Examples of bacterial wildlife diseases include: Tularema (rabbit fever), Lyme Disease, Leptospirosis. Examples of viral wildlife diseases include: Avian Flu, Ranavirus, Rabies, West-Nile Virus. Fungal pathogens such as White-Nosed syndrome impact North American bats. Chronic Wasting Disease is a prion disease that affects hoofed mammals in North America. Protozoans from contaminated sources can cause Giardiasis.

Symptoms and severity of wildlife diseases depend on many ecological factors as well as the interaction between virulence and host populations. Geographically, wildlife disease occur more frequently near tropical regions with higher biodiversity (Figure 1). However globalized trade has complicated the ecology of many pathogens, making it possible for them to disperse further than before. Additionally, some pathogens only infect specific organisms. Ecological studies suggest that “parasites can change the outcome of interspecific interactions including competition and predation, and can thus play keystone roles in determining species coexistence and biodiversity.” (Tompkins et al, 2011)

As scientists research more about the dynamics of wildlife diseases, they are discovering possible links to biodiversity loss and anthropogenic activities. While the complete relationship between humans and wildlife diseases is yet to be understood, many argue factors leading to increases in pathogen prevalence are “man-made and the trend will intensify with climate change, globalization, demographic evolution and linked new social behaviors.”(Wildlife Diseases, 2013) This perspective suggests that anthropogenic activities are indeed connected to wildlife diseases. Since Wildlife diseases are responsible for recent extinctions and mass mortality events in many species, it is important to look at them from a conservation perspective. If it is our goal to protect biodiversity worldwide, we must put dedication towards adequate research on the subject of wildlife diseases. We shouldn’t invest our resources in eradicating diseases, as they are important to biodiversity in their own right. It is more important to focus on achieving a better understanding of the role of wildlife diseases in global ecosystems.

Case Study of Pseudogymnoascus destructans:

Recently, North American species of bats have experienced a very high mortality rate due to the wildlife disease white-nosed syndrome. Among populations in North America, “5.7 -6.7 million” bats have died. Mortality rates often exceed “90 percent in caves that have experienced multiple years of infection.” (Indiana Department of Natural Resources, 2015). Scientists have identified a fungal pathogen, Pseudogymnoascus destructans (Pd, formerly known as Geomyces destructans), as the source of the infections. Pd is a psychoprophilic fungus, meaning it survives in cold temperatures. Psychoprophilic organisms are abundant around the globe, however Pd has been only problematic in the northeastern portion of North America and parts of Europe. At the end of the 2013-2014 hibernating season, “bats with WNS were confirmed in 25 states and five Canadian provinces.”(White-Nosed Syndrome, 2015) Since Pd is psychoprophic, it spores in the winter. Consequently, most North American bats hibernate in the winter. During their hibernation, bats immune systems are less capable of fighting of diseases. As a result Pd spores are more likely to infect bats, which then disperse the fungus. Pd causes “physical damage by the fungus from colonization of tissue, the infection also affects water retention, provokes more frequent arousal, and increases energy use that prematurely depletes fat reserves, leading to high mortality among the infected.”(Pseudogymnoascus Destructans, 2015) The fungus can be spread by both humans and bats, making it a complicated pathogen to control. Generally it is believed that Pd spreads from bat to bat. It is also possible that humans facilitate the spread through caving and research activities.

Ecological implications of WNS:

Understanding the principals of ecology, whenever any species declines rapidly, the surrounding ecosystem will be affected. Similar to every other species, Bats play very important roles in the communities they inhabit. Bats prey upon many types of insects, species which are normally pests to humans. Additionally, insects such as mosquitos may carry wildlife diseases of their own, such as the West Nile virus. Even bat droppings (guano) has been used as a fertilizer. Bats also play an important role in seed dispersal. Without ecologically effective numbers of bats in an ecosystem, populations of insects may increase and seeds may not disperse effectively. An ecosystem could end up losing additional biodiversity as a result of bat mortality. Changes in a community due to their absence are likely to have a negative impact on human life.

Role of Conservation:

While no research has suggested that Pd presents threats to humans, conservation actions are still very important. Since the fungus has been around for such a short time, little is known about how it is dispersed and what it is capable of infecting. Conservation actions taken now will have to address a number of questions that have not yet been answered in this short period of time. Currently, disease surveillance is a priority for conservation officials. Surveillance, or

disease monitoring involves researching population numbers and disease dynamics. Proper execution of surveillance gives scientists “the opportunity to adequately respond to unusual wildlife mortality events.” (Morner et al, 2002) Unfortunately many challenges exist to prevent significant progress towards finding a concrete conservation solution. Due to the widespread boundaries of Pd, it becomes difficult to govern a concentrated effort towards research funding. Within the United States, a team of federal and state agencies as well as local tribes have put together a management plan to respond to White-nosed syndrome. Additionally, research institutions have begun to investigate “Antifungal volatile organic compounds (VOCs), VOC formulations, essential oils, and other compounds… for their ability to inhibit fungal growth.” (Pseudogymnoascus Destructans, 2015) This type of research is in its early stages, however significant progress is being made. Currently, states that have confirmed the presence of Pd have closed cave sites to all forms of tourism. Their goal is to avoid the possibility of humans accidentally dispersing the pathogen which could cause additional ecological harm.

Discussion:

The spread of WNS exemplifies a catastrophic ecological event for a very important species. While we are not completely sure of the causes and solutions, we have been unable to find evidence that it is a phenomenon caused by anthropogenic activities. While other wildlife diseases seem to occur more frequently due to habitat degradation and climate change, WNS remains rather mysterious. This poses a large challenge to researchers dedicated to preventing extinction of such an important species. Without the proper amount of funding and support, we will never be able to fully understand our role in conserving valuable ecosystems. Additionally, without proof that humans are causing mass mortality and Pd spread, receiving research aid may be more difficult. Experts suggest that research teams will need to “adopt a multidisciplinary approach to identify underlying causes and to control [disease] spread.” (Daszak, 2000) I agree that this is a very necessary approach towards solving problematic and mysterious mass mortality. I only question whether or not policy makers or donors will feel inspired to help spend money on wildlife disease research that does not have a direct impact on human health. With WNS, only time will tell, fortunately small populations of bats are surviving, showing that the species may be resilient enough to naturally resist the threat of P. Destructans.

Figure 1:

Figure 1: Areas of high disease prevalence are red, whereas areas of low disease prevalence are green. (http://www.earth.columbia.edu/articles/view/2033)

References:

1. Tompkins, Daniel M., Alison M. Dunn, Matthew J. Smith, and Sandra Telfer. “Wildlife Diseases: From Individuals to Ecosystems: Ecology of Wildlife Diseases.” Journal of Animal Ecology 80, no. 1 (January 2011): 19–38. doi:10.1111/j.1365-2656.2010.01742.x.

2. "Wildlife Diseases." www.oie.int. January 1, 2013. Accessed March 5, 2015. http://www.oie.int/doc/ged/D14062.PDF

3. "Indiana Department of Natural Resources." DNR: White-nose Syndrome in Bats. Accessed March 6, 2015. http://www.in.gov/dnr/fishwild/5404.htm.

4. "White-Nose Syndrome." The Fungus. Accessed March 6, 2015. https://www.whitenosesyndrome.org/about/fungus.

5. "Pseudogymnoascus Destructans." Crow Laboratory at Georgia State University. Accessed March 6, 2015. http://sites.gsu.edu/crowlab/pseudogymnoascus-destructans/.

6. Morner, T., D. L. Obendorf, M. Artois, and M. H. Woodford. "Surveillance and monitoring of wildlife diseases." Revue Scientifique et Technique-Office International des Epizooties 21, no. 1 (2002): 67-76.

7. Daszak, P. “Emerging Infectious Diseases of Wildlife-- Threats to Biodiversity and Human Health.” Science 287, no. 5452 (January 21, 2000): 443–49. doi:10.1126/science.287.5452.443. http://www.sciencemag.org/content/287/5452/443.full.