Sunday, February 26, 2012

Friday Roundup-Eating Roadkill and Turtle Troubles in Canada

A New York Snapping Turtle
Protecting Snapping Turtles in Canada.  The distribution and range of a species is often heavily influenced by climate and habitat. If an area does not have suitable climate or habitat for a species, they cannot occur there. It's that simple. Polar Bears would not be comfortable in tropical jungles and you will not find Green Iguanas basking on icecaps. It gets a little more complicated at the edges of a species' range. In these borderline areas, the climate is often adequate for a species to live there, but it is not a perfect fit. This makes the species relatively more vulnerable to threats and dangers, like disease or harvesting by humans.

Snapping turtles, Chelydra serpentina, are a fairly common species found throughout eastern and central North America. But, they reach the northern extent of their range in Canada. Snapping Turtles rely on the environment to help regulate their body temperature and metabolism. And, as others have noted extensively, it can be tough for some species to adjust to northern latitudes.

Roads present unique dining opportunities
I've written previously about recent concern in many different areas (like Georgia and Alabama) about unregulated harvest of turtles. Now we can add Ontario, Canada to the list. Those in support of a ban on turtle harvesting say too many turtles are killed by cars and those that are harvested for food contain high levels of PCBs and mercury. Not quite the condiments I would choose.

Speaking of Roadkill (and Dinner). A recent article from The Ecologist ponders the ethics, legality, and gross-factor of eating animals, like squirrels, that have been run over by cars. I am guilty of eating both deer and rattlesnake found on road (the deer was most exceptional, the rattlesnake was perhaps a tad overcooked). I would be very interested to know of your experiences with similarly tenderized meals.


A Tiger Salamander, of the Ambystomatid family


Continuing the Theme of Roadkill. Every year, many salamanders (particularly those within the Ambystomatid family) conduct migrations from the forest (where they spend most of their time) to wetlands (where they mate and reproduce). The timing of these migrations vary depending on where the salamanders are in North America, but they often occur in late winter or early spring during cold rains. When roads have been constructed in between forests and wetlands, salamanders may find that their historic migration routes now include a deadly gauntlet over a paved highway. The New York Times offers this story about a group of volunteers concerned about the plight of Spotted Salamanders, Ambystoma maculatum, making their way across the Natchez Trace Parkway in Mississippi.

A Georgia Snapping Turtle
Snapping Turtles Are Not the Only Species in Trouble at the Edge of Their Range. The state of Vermont used to pay bounties on Timber Rattlesnakes, Crotalus horridus. Now, after decades of persecution, one of the rarest species in the state is getting a helping hand.

A New Threat for a Historically Persecuted Species. As if rattlesnakes did not have enough to worry about with the loss of their habitats and bad reputation, now Eastern Massasaugas, Sistrurus catenatus, are thought to be succumbing to a deadly fungus in Illinois. It is not yet known how widespread of a concern this new threat may be. You can read more here.

A Sunburn May be the Least of Our Concerns. I have always questioned the logic of coating our bodies with insect repellent. If a tiny insect brain knows enough to stay away from these harmful chemicals, I am not sure why we would risk spraying it all over ourselves. Elizabeth Preston at Inkfish summarizes a recent article that describes how fish metabolism is altered when they are exposed to commercially produced nanoparticles (like those present in suntan lotion, for example).



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Want to learn more? Citations to relevant scientific articles are provided below.

Cedervall, T., Hansson, L., Lard, M, Frohm, B, & Linse, S (2012). Food Chain Transport of Nanoparticles Affects Behaviour and Fat Metabolism in Fish PLoS ONE, 7 (2)

de Solla SR, Bishop CA, Lickers H, & Jock K (2001). Organochlorine pesticides, PCBs, dibenzodioxin, and furan concentrations in common snapping turtle eggs (Chelydra serpentina serpentina) in Akwesasne, Mohawk Territory, Ontario, Canada. Archives of environmental contamination and toxicology, 40 (3), 410-7 PMID: 11443374

Allender MC, Dreslik M, Wylie S, Phillips C, Wylie DB, Maddox C, Delaney MA, & Kinsel MJ (2011). Chrysosporium sp. infection in eastern massasauga rattlesnakes. Emerging infectious diseases, 17 (12), 2383-4 PMID: 22172594

Friday, February 17, 2012

The Chemistry of Turtles

The following article is a guest post by Sean Sterrett. I would like to feature more guest posts here in the future; please contact me if you're interested in contributing. Want to see more posts from Sean or other potential future guest bloggers? Encourage them by letting them know what you think in the Comments. Don't forget to subscribe to this blog here.

Sean Sterrett currently lives in Athens, Georgia and is a Ph.D. student at the University of Georgia researching the ecological roles that reptiles play in aquatic ecosystems.  Sean hails originally from Indiana, where he received his B.Sc. degree in Biology from Butler University.  Sean first travelled to Athens in 2004 to pursue a M.Sc. degree; he studied the impacts of land use on riverine turtle communities (I wrote about helping him with his fieldwork here).  Sean is an avid freshwater kayaker (a great way to see turtles), vegetable gardener and homebrewer.  

The field of conservation biology is often described as having arisen in response to urgent and global biodiversity losses in the latter part of the 20th century.  Since then, scientists have dedicated their careers (and lots of money) into figuring out how to improve the ability of animal populations to persist while conserving the habitats that they rely on.  Most scientists would agree that there are two major reasons for learning about how humans have impacted wildlife and natural ecosystems: intrinsic and ecological values.

Intrinsic value, or the ethical value placed upon something for its own sake, is one reason that people are inspired to learn about and study animals and ecosystems.  This has even led to a new sub-discipline of ecological philosophy known as "deep ecology."  For me, intrinsic value is rather simple to describe. I do not want to live in a world without its amazing animals, like tigers, elephants, pythons and sea turtles. Recognizing that I valued these animals inspired me to become a biologist.

The ecological value of animals, on the other hand, is more challenging to pinpoint.  Numerous studies have described what happens when certain species are reduced in numbers or even removed from their natural habitats. One striking example involves Gray Wolves, Canis lupus, in Yellowstone National Park. After being persecuted for many years, all of the wolves in Yellowstone National Park were killed off (they have since been reintroduced). Surprisingly, the disappearance of the wolf had trickling effects all the way down to evergreen trees.  Here’s how it happened: when wolves were removed, the pressure was taken off of populations of prey, such as Elk, Cervus elaphus. Elk are herbivorous and feed heavily on plant material.  Therefore, when the wolves were removed from the equation, elk populations grew larger and browsed plants at an increased rate.  So, wolves indirectly influenced forest structure and vegetation communities. These types of indirect effects are known in the ecological literature as trophic cascades.

Historically, top predators kept many of these cascades in check. Because I study reptilian ecology, it is worth mentioning that there are likely similar impacts occurring due to the loss of other top predators, such as Eastern Diamondback Rattlesnakes, Crotalus adamanteus. However, many of these impacts have yet to be studied or measured.

Predator and prey relationships are not the only ways wildlife species influence their surroundings. Here, I want to highlight the chemical roles of vertebrate animals.  Many studies have described how fish recycle and transport nutrients within aquatic ecosystems.  For example, gizzard shad (a small fish) feed in the bottom of lakes and can liberate stored nutrients, which then become incorporated into food webs. I would hope this might impress you?  If not, I will add that this type of nutrient "addition" to a lake can meet or even exceed external sources of nutrients, such as streams or atmospheric inputs.  There is a growing body of research describing how nutrients flow through ecosystems. After reading many papers on the subject, I now consider the world as one big chemical reaction. 

Trapping turtles may sometimes offer big surprises
When I was an undergraduate at Butler University in Indianapolis, Indiana, I was more interested in helping out on the Urban Turtle Ecology Research Project (UTERP) than studying for chemistry classes. Ironically, now as a PhD. student at the University of Georgia, those same laws of chemistry that I did not want to learn are now major components of my current research on turtle ecology.  So, how is it possible to integrate freshwater turtles and chemistry?

Well, just like the gizzard shad, turtles eat a variety of plants and animals.  Part of what they eat goes toward growing and maintenance of their body.  Other parts are used as energy for reproduction.  When turtles excrete ("poo" and "wee"), they are getting rid of waste materials that they don't need.  But one creature’s waste is another’s treasure. That "waste" material is made of elemental nutrients (remember the periodical table of elements?). These nutrients are used by many other life forms, especially aquatic plants and algae, which make up the base of most food webs.

There are many different species of freshwater turtle and some can be found in just about every type of wetland, including those uninhabitable by other animals. Turtles can make up a significant amount of animal biomass in aquatic ecosystems (the total weight of turtles in a lake can be close to the weight of all the fish). They also have some interesting characteristics that make them different from fishes and other aquatic organisms in their habitats.  First, turtles live very long lives. Each animal can influence its aquatic habitat for many years.  Second, turtles have one of the most formidable evolutionary defense structures of any animal: a shell. Their shell is composed largely of bone, which is packed full of calcium and phosphorus. When a turtle dies and decomposes, these nutrients are then released into the environment.

Incubation trials of riverine turtles
 in the Lower Flint River Basin
One objective of my doctoral research is to figure out how turtles impact aquatic ecosystems via excretion and retention of nutrients; nutrients that are necessary for functioning aquatic ecosystems.  I'm studying these questions using very common species in the southeastern U.S., a global hotspot for turtle diversity.  The photo below shows how I'm approaching the problem of determining the rates of excretion from turtles.  This process involves first catching turtles, then placing them in filtered water and taking a series of water samples for nutrient analysis.  Although it sounds simple, the process is labor intensive and logistically challenging, especially considering the hefty amount of materials I need to pack into my remote field sites, some of which are most accessible by boat.

So...turtles are certainly important members of aquatic ecosystems as consumers. I hope my research allows us to determine how they are chemically influencing their habitats and other animals. What if there weren’t any turtles around, would their chemical roles be missed?






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Subscribe to this blog by e-mail here. Want to learn more? Check out these articles.

RIPPLE, W., & BESCHTA, R. (2004). Wolves and the Ecology of Fear: Can Predation Risk Structure Ecosystems? BioScience, 54 (8) DOI: 10.1641/0006-3568(2004)054[0755:WATEOF]2.0.CO;2

SCHAUS, M., VANNI, M., WISSING, T., BREMIGAN, M., GARVEY, J., & STEIN, R. (1997). Nitrogen and phosphorus excretion by detritivorous gizzard shad in a reservoir ecosystem Limnology and Oceanography, 42 (6), 1386-1397 DOI: 10.4319/lo.1997.42.6.1386

Friday Roundup-Alabama Turtles, Florida Pythons, and Mystery Meat

Are Alabama Turtles the Next Target? A couple weeks ago, I wrote about how Georgia recently enacted new laws to help protect their native turtle populations. By creating limits on the number of turtles one person can catch, the Georgia Department of Natural Resources hoped to regulate the likely-unsustainable harvest. Turtle populations just do not grow fast enough to replace the many individuals that were being removed and shipped overseas for food.

Because it is now more difficult to profit off of catching turtles in Georgia (and Florida has even stricter regulations), there is some concern that out-of-state turtle harvesters have turned their attention to Alabama. In recent years, Alabama has shown that they take turtle conservation seriously. We will have to wait and see if they follow the lead of Georgia and Florida and respond to citizens' comments by approving new regulations.

Auburn Dogs on the Hunt for Florida Pythons: In recent years, there have been many legitimate concerns raised about pythons prowling through south Florida. These pythons, likely descended from released (or escaped) pets, are having big impacts on native wildlife populations. And, it doesn't look like there is much to stop them from expanding their range.

Researchers have been working hard to develop and evaluate different methods of tracking down wild pythons. Some Auburn colleagues of mine recently revealed their preferred strategy: using specially trained dogs. Last summer I spent some time in the Everglades helping out on their project, I have been meaning to write more about it here...

What's the Catch of the Day? I have written in the past about how I feel it is important to know where your food is coming from. But, figuring out this information first requires that you know what you are eating. If you like seafood, this can be surprisingly difficult.

From the blog Salamander Hours comes an interesting summary of some recent research that uses DNA analyses to show that seafood products are often mislabeled. The species you are eating is often not the species listed in the ingredients. In some cases, these analyses can reveal that rare species, species that should not be harvested, are showing up in supermarkets disguised as something else.

What do Marine Biologists do? From the Deep Sea News blog, an amusing graphic regarding perceptions of what marine biologists do. I think much can be also be applied to us biologists that tend to work on land.




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Links to some relevant scientific articles are provided below:

Hart, K., Schofield, P., & Gregoire, D. (2012). Experimentally derived salinity tolerance of hatchling Burmese pythons (Python molurus bivittatus) from the Everglades, Florida (USA) Journal of Experimental Marine Biology and Ecology, 413, 56-59 DOI: 10.1016/j.jembe.2011.11.021


Dorcas ME, Willson JD, Reed RN, Snow RW, Rochford MR, Miller MA, Meshaka WE Jr, Andreadis PT, Mazzotti FJ, Romagosa CM, & Hart KM (2012). Severe mammal declines coincide with proliferation of invasive Burmese pythons in Everglades National Park. Proceedings of the National Academy of Sciences of the United States of America, 109 (7), 2418-22 PMID: 22308381

Friday, February 3, 2012

Friday Roundup-Rattlesnake Festivals and New Vipers Discovered

Making Strides in Georgia: In recent weeks, there have been many news stories coming out of Georgia that demonstrate how committed individuals and organizations have been making great strides in reptile conservation.

I have written previously about rattlesnake roundups in the southeastern United States (as have others). These events encourage people to catch rattlesnakes over the course of the year and transport them to one of a handful of Georgia and Alabama towns. At the roundups, the snakes are displayed, generally mistreated, and then killed. Many people who support these events dismiss critics as simply animal-rights fanatics. Although it is true that the individual animals captured for the roundups are killed, there are also concerns about wildlife populations and their habitats. Recent research has demonstrated that the sizes of the rattlesnakes brought into the roundups are decreasing over time, this is a sure-sign that populations are being over-harvested. In addition, collecting rattlesnakes often involves techniques that are damaging to natural habitats, like pouring gasoline down Gopher Tortoise burrows.

Many conservation organizations have offered assistance to roundup organizers if they wanted to transition to more wildlife-friendly events, but these offers have generally not been well-received.

That's not entirely true. Fitzgerald, Georgia stopped rounding up rattlesnakes and now holds a wild chicken festival; I encourage everyone to support that city by attending this annual event.

But recently, some big news from Claxton, Georgia. The Evans County Wildlife Club, which has organized the Claxton Rattlesnake Roundup since 1968, will no longer buy or sell wild rattlesnakes. Appropriately, they have switched the name of their event to the Claxton Rattlesnake and Wildlife Festival. From the article I link to above, the president of the Evans County Wildlife Club states,


 “We want to shift gears from a rattlesnake roundup where everybody came to see rattlesnakes to a wildlife festival where we’re promoting wildlife and educating people about wildlife and the conservation of wildlife. I think we can open this event up and the possibilities for our promoting and protecting wildlife are endless.”


I urge everyone to support the decision of the Evans County Wildlife Club by attending their festival, in the second week of March. Kudos to Claxton and all the organizations that helped assist with the transition.


Also from Georgia is the recent news that people will no longer be able to harvest as many turtles as they want. In the last few years, a lot of concern has been raised about the commercial exploitation of freshwater turtles. Apparently, people have been trapping turtles and then exporting these animals to other countries, where they are eaten. If it was only a few turtles, there would not have been much fuss, but we are talking about thousands upon thousands of our turtles being shipped off each year. 


In response to this threat to our native turtle populations, several southeastern states quickly adopted regulations that would limit this unregulated exploitation. But, Georgia was slow to act. Now, they've made up for their tortoise pace. Trappers can still harvest turtles, but the scale of this activity has been reduced to help ensure Georgia's turtles don't disappear overseas.


Congratulations to Georgia for working to stop unregulated harvest of their native species.


A New Species of Viper in Tanzania: Researchers have identified a new species of viper from the mountains of Tanzania. The exact location is being kept secret so snake-fanciers do not invade the area to collect the snake, which may already be highly imperiled. In fact, it has been suggested that the species is critically endangered because of the loss of its habitat. In response, the researchers have initiated some non-traditional conservation strategies.


What Does a Binturong Butt Smell Like? Many zookeepers will already know the answer to this question (popcorn). But, this article, which explains how some animals use scents to communicate, reminded me of the scent of Eastern Diamondback Rattlesnake musk (which I think smells like Doritos).

How Are Snakes Related? The business of figuring out how different species of snakes are related is a complicated matter. If you were at all intrigued by the discussion of snapping turtle genetics in the comments section of my last blog post, check out this relatively technical blog explaining snake relationships.


Rat Snake Freakout: Finally, just for fun. Here is another example of a harmless Florida species being mistaken for an exotic python.



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Much of what I write is based on my experience in the field. However, I also rely on the research of others. Links to relevant scientific articles are provided below.

D. B. Means (2009). EFFECTS OF RATTLESNAKE ROUNDUPS ON THE EASTERN DIAMONDBACK RATTLESNAKE (CROTALUS ADAMANTEUS) Herpetological Conservation and Biology, 4, 132-141

Brown, D., Farallo, V., Dixon, J., Baccus, J., Simpson, T., & Forstner, M. (2011). Freshwater turtle conservation in Texas: harvest effects and efficacy of the current management regime The Journal of Wildlife Management, 75 (3), 486-494 DOI: 10.1002/jwmg.73