Wednesday, June 13, 2012

New threats call for new partnerships in wildlife conservation

 New threats call for new partnerships in wildlife conservation

Note: This piece ran in the Sunday, June 3, News-Gazette, but I haven't figured out a way to fit it into a radio spot so there's no audio version of it. -rk

Last spring, some mushroom hunters made a strange and unsettling discovery at Forest Glen Preserve in Vermilion County, a group of about 50 dead box turtles. Or, to be more precise, the closed, empty shells of the deceased turtles.

According to Chris Phillips, who is a herpetologist with the Illinois Natural History Survey, a division of the Prairie Research Institute at the University of Illinois, a total of 65 shells were ultimately found in the area. They were dispersed in a way suggesting they had died where they lived--that is, they had not become infected elsewhere and been dumped there.

What killed them? Phillips says the shells yielded few clues. Unlike the shells of turtles that have died under normal circumstances, they were devoid of any soft tissue, but the bones of the pelvic and shoulder girdle were inside. This was odd since it meant that the animals were in their shells when they died and nothing scavenged them enough to get the bones out.

Sealing themselves off from enemies is, in most cases, an excellent defense for eastern box turtles, which may live to an age of 50 years or more, even in the wild. But the turtles involved in last year’s die-off at Forest Glen obviously met up with an out-of-the-ordinary foe.

[Photos: above, a healthy eastern box turtle (Chris Phillips); below, Matt Allendar draws blood from a turtle with its shell propped open (Rob Kanter).]

Fortunately, it was possible to identify a culprit through an examination of living turtles discovered in the same area. Phillips and others collected 12 of them. Of those 12, five were missing all or part of a leg, the result of an aggressive bacterial infection that subsequently killed them, too.

If Phillips had been the only researcher to handle the living turtles found at Forest Glen, he might never have even witnessed the grisly effect the infection had on them. That’s because the ecological and genetic data he collects can be taken while a turtle’s shell is closed, with the head and legs out of view.

But Phillips was examining the turtles together with Matt Allender, who is a wildlife veterinarian and instructor in comparative biosciences at the UI. Allender’s assessment of the turtles required waiting until they opened their shells, and at that point their affliction was apparent.

Phillips and Allender, who have known each other since Allender was a student in Phillips’ UI herpetology class in 2000, are collaborating in a one-of-a-kind effort to combine long-term ecological data about box turtles with periodic health assessments.

Phillips and his students from the UI Department of Natural Resources and Environmental Sciences seek to understand how certain populations of box turtles in east central Illinois are faring over time. Toward that end, they’ve been capturing and marking turtles at three sites in the Vermilion Valley since 2009. Such work allows for an assessment of the status of the population now, and provides data to predict the likelihood the population will survive 50 or 100 years into the future. This is the classic wildlife ecology approach that has been practiced for decades. 

Allender and his students from the College of Veterinary Medicine seek to profile the health of turtle populations at a given time by analyzing the physical condition of individual animals.

Much of their analysis is done through blood work.  They monitor the immune system by checking for anemia or elevated white blood cell counts. They test for the presence of ranavirus, a pathogen that has been linked to mass deaths of a variety of reptiles and amphibians worldwide. And they look for evidence of exposure to environmental toxins, such as lead and zinc, which compromise health by suppressing the immune system, even at low levels.

Such work has not typically been integrated with wildlife ecology in the past, but Allender thinks it could play an important role in future conservation decisions. For example, he says it could provide evidence of whether or not turtles experience health effects from living in habitats dominated by invasive species, or how the extent of habitat available affects a population’s capacity to withstand disease.

There was a time in the not too distant past when the threat of disease scarcely entered the calculations of people who were concerned with the welfare of wildlife, and habitat seemed to be everything. It was widely assumed that if people could just preserve or reconstruct the right amount of the right kind of habitat, they could ensure the continued existence of many species, especially ones facing no immediate threats of overexploitation or exposure to obvious toxins.

Such thinking caused Phillips to assume that he and Allender were parting ways for good back in 2000. “Knowing that Matt was going to vet school, I thought, that's too bad, I'll never run into this bright kid again.  He's going to treat cats and dogs, or end up at a zoo.  It didn't dawn on me at that time that there was even a remote chance that I would ever need to collaborate with a vet.  Even when he approached me about doing a Master’s degree on the health of massasauga rattlesnakes at our study site near Carlyle (Illinois), I thought, well, as long as he doesn't get in our way.”

More recently, however, the emergence of devastating pathogens in a variety of species around the world has caused Phillips and others who have spent their careers doing traditional wildlife ecology to reconsider. As Phillips puts it, “Habitat does little good when entire populations are destroyed by disease.” 

Perhaps the most well known of these is the notorious white-nose syndrome, which has killed North American bats by the millions since its emergence in 2006, wiping out entire colonies of some species as it spreads.

Among reptiles and amphibians, two diseases have had dramatic impacts around the world. A chytrid fungus, B. dendrobatidis, has led to the extinction of localized frog and toad populations in many places, and possibly entire species in some cases. Ranaviruses have killed numbers of amphibians ranging from one to 1,500 in populations where they have struck across the Unites States, Canada, and western Europe. Ranaviruses have been proposed as a major threat to biodiversity in North America.

Close to home, Allender recently identified a fungus, Chrysosporium, as the cause of death for four of the eastern massasauga rattlesnakes from the already dwindling population near Carlyle. (Massassaugas are already classified as endangered in the state, and they appear to be headed for federal listing soon, too.) According to Allender, the genus Chrysosporium infection has long been a problem among captive reptiles, but this species of Chysosporium has not previously been identified as a problem in captive or wild animals.

At the same time Chrysosporium has become a problem for massasaugas in Illinois, it has also caused significant losses among struggling populations of timber rattlesnakes in New Hampshire and Massachusetts, where it was also not previously known as a problem. In fact, since the December 2011 publication of a paper about the infection in Illinois, Allender has received nearly a dozen reports of similar infections from five states east of the Mississippi.

The turtles involved in last year’s die-off at Forest Glen were afflicted by none of the above maladies, but rather a bacterial infection.

According to Allender, the bacterium responsible for it occurs in many environments. While it’s capable of infecting a wide range of hosts, including birds and mammals, it is also commonly present without causing infection. He suspects that the health of the afflicted turtles had already been compromised in some other way, and hopes that further study will reveal how.

Allender says he has never seen such an infection in his previous work with box turtles, and he knows of no other reports of it elsewhere. He’s certain it’s not a one-time occurrence, though, since five of the turtles he and Phillips captured for study at another site this year exhibited lesions similar to those on the turtles from Forest Glen.

Whether or not this bacterial infection turns out to be a large-scale, ongoing problem for box turtles, Phillips and Allender both see it as a clear indicator of the need for biologists and veterinarians to cooperate in the cause of wildlife conservation.