Wednesday, April 21, 2010

Oh those poor bats...

As summer approaches, I can't help but think of going caving again. Crawling through tight spaces and climbing down cliffs is such an adrenaline rush; plus it's a great way to learn some pretty cool science. Please allow me to encourage you to go!

I hear people saying all the time that being short has its perks, but I know of one situation in which it's a curse. While at Mammoth Cave, our guide took us to a drop which they call the Lion's Head. As you can see, I'm (yes, that's me!) hanging on for dear life (actually I'm having the time of my life)! Even though the floor is about 5 feet under me I still don't want to fall. Plus there's a huge stalagmite below not pictured prepared to attack, giving the formation the title of the Lion's Head. However, the tour guides there are helpful and make sure that you get down safely. Anyway, aside from the crazy expeditions, you can learn many things from going on a tour like this. You can learn about the glittering water in the cave that contains many organisms and certain minerals. You can also learn about certain epidemics that are affecting certain native species. For example, bats living in the caves are starting to contract a particular fungus. This fungus grows on their noses, killing them and affecting their natural behavior. This is known as the white nose syndrome and has effected many bats. It can be transferred to bats via humans. The syndrome also spreads amongst bats. I find this interesting and important because the bat population is steadily decreasing due to this malicious killer. Since the introduction of the white nose syndrome, the bat population in 2 New York caves was found to be reduced by 75% [1]. This disease has spread to other caves in North America and researchers are studying this more to gain more of an insight into what it is and how to treat it.

I did a little more research on the subject because I want to know more about it. I found one paper by Courtin et al titled "Pathologic Findings and Liver Elements in Hibernating Bats With White-Nose Syndrome" that discussed this disease. The paper gave a great overview of the disease and did a nice job This malicious disease first appeared in 2006 in a New York cave and then spread throughout the Northeast during the winters of 2007 and 2008. By 2009 it had found its way to Pennsylvania and Virginia [1]. The bats most commonly affected are the little brown, northern-long eared, and big brown species. When they examined some of the bats, they found lesions on the muzzle and wings. Geomyces destructans, a white fungus, was found around these lesions. Behavioral differences were also seen. Some of the bats flew out of the caves in the middle of winter during hibernation and some even flew during the day. What is interesting about this study is that they analyzed the lesions and looked to see if there were any metals or minerals at abnormal levels. This could correlate to the disease [1].

For this experiment, they collected dead or almost-dead bats with the disease. They collected two groups: one for microbiological examination and the other for metal and mineral analysis. In the examination group they found that the dead bats had fungus that started to penetrate the basement membrane of the root sheaths and into surrounding tissues, but this was not the case in the almost-dead bats. They also found that the body weights of the bats were on the low side. They found that the fungal hyphae grew along the hair follicles and also went along the surface of the skin in hairless places such as on the wings. One interesting thing Courtin et al discussed was that this type of fungus is that it can extend into the epidermis, near the noncorneal layers as well as the sebaceous glands [1]. While examining the bats, they also found that there was fungus growing, as well as gram-negative bacteria, in the dermal-epidermal interface. They also found no organ failure in these bats.

In the second group, they analyzed the livers for different metals. They found that most metal levels varied and were not consistent. Courtin et al collected several different species of bats (they are listed above). They found, along with other labs, that the little brown bat is more commonly afflicted with the fungus, whereas the the big brown bats are not. They believe this could be due to the areas in which the big brown bats hibernate. They hibernate in drier, ventilated areas whereas the little brown bats do not. So, in conclusion, their home choice could have an effect on their susceptibility to this fungus [1].

I don't know about you, but I can't help but think of these poor bats. So, if you do go caving, please, don't touch the bats. Even though the Mammoth Cave bats have not seen this fungus as of now, there is still the potential that it could be introduced.

[1] Courtin, F., Stone, W. B., Risatti, G., Gilbert, K., & Van Kruiningen, H. (2010). Pathologic findings and liver elements in hibernating bats with white-nose syndrome. Veterinary pathology, 47(2), 214-219.

Photo of bat from Courtin et al, (2010).

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