The federally Threatened bog turtle faces a new threat in the northern portion of its contiguous range. On August 5th, the USFWS issued an advisory bulletin that an unusually high number of dead and apparently diseased bog turtles have been reported from four states, including New York and Massachusetts. I received the alert by email from a colleague and the full bulletin is reposted here.
"...The number of bog turtles found dead in their wetland habitat (2 to 4 dead turtles in each of four wetlands in NY and MA) exceeds that which is typically reported.
In some cases, dead bog turtles have been found entirely intact, with no obvious cause of death.
On several live bog turtles, a grayish or whitish substance and/or discoloration has been
documented on the skin of the head, neck and limbs, as well as on the claws. In some cases,
these appear as skin lesions. Scute sloughing and loss of claws and toes has also been observed.
Based on data collected at a Massachusetts site, the symptoms appear to worsen over time.
At this time, the causative agent(s) of the observed symptoms has not been identified..."
This is extremely troubling news. When I was with The Nature Conservancy, bog turtle conservation in Massachusetts, Connecticut and part of Eastern New York was a major focus of my work. The bog turtle is at the extreme northern extrent of its contiguous range in Massachusett. The USFWS Recovery Plan for the bog turtle's northern population identies just three bog turtle sites in the Commonwealth, but two of them are considered good sites and are under conservation management. I am intimately familiar with both of these, and know that if one has lost 2-4 adults to a new threat the viability of what would otherwise be considered a strong and vital population is in grave peril. Past research indicates that the loss of just one breeding adult a year at these sites would be enough to tip the balance toward extirpation.
The 2001 rare species recovery plan records what was known at that time about the threat posted to wild bog turtle populations by disease (my emphasis added):
"...At present, there are no substantiated reports of disease affecting a wild population of bog turtles, although at one site in Columbia County, New York (J. L. Behler, pers. comm) the number of dead turtles is cause for concern; eight dead bog turtles were collected during three visits to the site in 1988 and 1989 ( A. breisch, in Mt. 2000). A sick turtle removed from that population and held for several years in captivity tested positive for upper respiratory distress syndrome (URDS) upon necropy (J. L. Behler, pers. comm.). Although this could indicate a health problem within that communication, it is also possible that the turtle contracted this disease while in captivity. Disease issues have the potential to become a much larger threat to wild bog turtle populations as they are subjected to more handling by researchers or if manipulation of turtle populations is undertaken through the deliberate release into the wild of bog turtles from other areas, zoological collections, or those seized by law enforcement activities. It should be noted that thorough health screening of wild-caught bog turtles has not been a standard practice of researchers, although it may be warranted (Smith in iitt. 2001)..."
I do not know for certain whether all four sites where increased mortality and apparent disease have been observed coincide with those where there has been more handling by researchers, but it is highly likely at least at the first site where such observations were made, because very few people besides researchers even know where the turtles are or would know to report what they had observed to the proper authorities. In the Massachusetts case, only researchers have legal access to the sites.
There is additional publically available data concerning the possibly diseased bog turtle site in new York mentioned in 2001 rare species recovery plan. Beacham's Guide to the Endangered Species of North America (2000) identifies the respiratory disease at that site as Mycoplasma:
"...Of additional concern is the recent (1997) discovery of Mycoplasma (the bacterium that adversely affects the desert tortoise) at a bog turtle site in New York. This disease has the potential to cause significant declines in bog turtle populations. The site where Mycoplasma has been discovered has been identified as one of the best remaining New York sites and lies in a valley with additional, extant sites leading to the possibility of spread of the disease through a significant portion of the remaining bog turtle range in New York State..."
The USFWS disease alert makes no mention of Mycoplasma and instead describes different symptoms. That is what is most alarming about this new threat. An unknown and highly lethal pathogen will take time to analyze, let alone isolate causes and develop a meaningful response. Bog turtles do not have any time. their populations are too small.
Consider that in 2006, a new disease affecting little brown bats in New York was first described for science. Three years later, white nose syndrome is causing up to 90-100% mortality in bat caves from the White Mountains of New Hampsive to sw Virginia. It has affected between 500,000 and 1,000,000 bats of several different species. There is still no absolute cause for this disease, nor a cure. One theory is that human activity may have been an initial vector for the spread of the fungus.
I suspect that the reason this new turtle disease has not yet been reported in Connecticut is that no researcher has been to our few remaining (and much poorer quality) bog turtle sites to check. There has not been a live turtle reported from a couple of these places in years. I am aware that several years ago, one Connecticut turtle was found by a passerby and taken to a public beach where it was spotted by a knowledgable person and ultimately returned to the site where it belonged. My understanding is that this turtle was later found dead.
This leaves open a difficult question. Should researchers visit other bog turtle sites to determine whether they, too, have evidence of increased mortality and apparant disease? Or should they refrain from doing so, given the potential that their activity could be contaminating clean sites? The felt soles of waders are known sources of introducing the microscopic alga Didymosphenia geminata or "Rock Snot" to trout streams. Unless soaked for at least 40 minutes in hot water at least 113° F (45° C) - or for 30 minutes with a 5% solution of dishwashing detergent - what keeps a researcher dry may be killing the very things they care for.