Sunday, October 31, 2010

Atlantic Sea Turtle Population Threatened by Egg Infection

The following press release is from Eurkea Alert. An international team of Mycologists and Ecologists studying Atlantic sea turtles at Cape Verde have discovered that the species is under threat from a fungal infection which targets eggs. The research, published in FEMS Microbiology Letters, reveals how the fungus Fusarium solani may have played a key role in the 30-year decline in turtle numbers.

"In the past 30 years we have witnessed an abrupt decline in the number of nesting beaches of sea turtles worldwide," said Drs. Javier Diéguez-Uribeondo and Adolfo Marco from Consejo Superior de Investigaciones Cientificas- CSIC Spain. "While many of the reasons for this are related to the human impact of the coastal environment it has been suspected that the decline is also due to pathogenic microorganisms."

Fusarium solani is a complex fungal strain which represents over 45 phylogenetic and biological species. The fungus is distributed through soil and can cause serious plant diseases. The fungus is known to have infected at least 111 plant species spanning 87 genera and has also been shown to cause disease in other animals with immunodeficiency.

During embryonic development turtle eggs spend long periods covered by sand under conditions of high humidity and warm temperatures, which are known to favor the growth of soil-born fungi.

Dr Diéguez-Uribeondo's team focused their study on the Loggerhead Sea Turtle (Caretta caretta) population on Boavista Island, Cape Verde, off the West African coast. While Boavista Island represents one of the most important nesting regions for this species a high hatching failure rate is driving population numbers down.

The team sampled egg shells with early and severe symptoms of infection, as well as diseased embryos from sea turtle nests located in Ervatao, Joao Barrosa and Curral Velho beaches and discovered 25 isolates of F. solani associated with egg mass mortalities.

Although this fungal species has been previously described in association with different infections in animals, its relationship to hatching failure had not been investigated before this study.

The finding that strains of F. solani may act as a primary pathogen in loggerhead sea turtles represents an extremely high risk to the conservation of loggerhead sea turtles across the area.

However, the description of these particular fungal strains causing this infection may help in developing conservation programs based on artificial incubation and may aid the development of preventative methods in the field to reduce or totally erase the presence of F. solani in turtle nests.

"This work reveals that a strain of F. solani is responsible for the symptoms observed on turtle nesting beaches," concluded Dr Diéguez-Uribeondo. "This shows that the infection represents a serious risk for the survival of this endangered species, while also showing immunologists and conservationists where to focus their research."

Citation: Sarmiento-Ramírez, J. M., Abella, E., Martín, M. P., Tellería, M. T., López-Jurado, L. F., Marco, A. and Diéguez-Uribeondo, J. (2010), Fusarium solani is responsible for mass mortalities in nests of loggerhead sea turtle, Caretta caretta, in Boavista, Cape Verde. FEMS Microbiology Letters, 312: 192–200. doi: 10.1111/j.1574-6968.2010.02116.x

Two Stories: Amazonian Drought and Biodiversity Politics

 Two stories that have implications for the loss of squamate diversity and the protection of squamates, as well as the rest of the flora and fauna are on the web this morning:

Jeff Tollefson on Nature's web site (October 29, 2010) is reporting on the second Amazonian drought in five years, data from terrestrial weather stations as well as satellites suggest the 2010 drought is broader but less intense than the 2005 drought.The current drought has affected a large area in the northwest, central and southwest Amazon, includes parts of Columbia, Peru and northern Bolivia. Fewer clouds and less rain also translate into higher temperatures, and the maximum temperatures in September are 1 °C higher than 2005, and 2–3 °C higher than average. Water levels in the primary tributary Rio Negro — or Black River — are at historic lows. Deforestation in Brazil has decreased by 85% since 2004, but there have been reports of increased fire activity. that may be related to the drought. Forest fires are generally associated with deforestation, but drought amplifies the impact of fires that are set in order to clear land.

The AAAS web site is carrying a story (October 29, 2010) that negotiators at the Convention on Biological Diversity (CBD) in Nagoya have agreed to take action on the loss of biodiversity. The CBD has representatives from 179 countries and they want to try to ensure the resilience of ecosystems by 2020.They also adopted agreements to generate financing to support these efforts and to share the proceeds of the commercialization of genetic materials with the countries of origin. The strategic plan sets 20 specific targets to achieve by 2020. Key targets include conserving in protected zones at least 17% of the world's terrestrial and inland water areas and 10% of coastal and marine areas, halving the rate of loss of all natural habitats, including forests, and preventing the extinction of known threatened species. As well as eliminating subsidies harmful to biodiversity, managing fisheries sustainably, and minimizing anthropogenic pressures on coral reefs.

Saturday, October 30, 2010

The Aesculapian Snake and Human Activity


Humans (including Homo erectus, Neanderthals, and Homo sapiens), have been in Europe for about 2 million years. Therefore humans have interacted with the European landscape and its fauna for a considerable amount of time. One of the snakes humans have impacted is the Aesculapian Snake, Zamenis longissimus (formerly Elaphe longissimus). It is of interest for its role in Greek mythology and in ancient Greek and Roman medicine. The staff of Aesculapius, a long standing symbol of healing and medicine shows this snake coiled around the staff and the image as well as the snake has been long associated with healing. 

While the Aesculapian Snake appears to be widespread in southern Europe, it has a few, small isolated populations in northern Europe. It is also known from fossil remains in northern areas where it currently does not exist, suggesting that longissimus once had a greater natural distribution than it does today. Or, that human transported this snake, possibly for its medical value into more northern latitudes. The first hypothesis is now seen as the more likely scenario to understanding its current relictual distribution and fossil remains. However, this does not mean humans have not introduced this snake at some localities, a population of Aesculapian Snakes is established in the Welsh Mountain Zoo in and nearby gardens; and it is also living in Regent's Park and along the Regent's Canal in the centre of London. This population is thought to have resulted from animals that escaped from the London Zoo.

Capizzi et al. (2008) examined the food habits the Aesculapian Snake in three areas of central Italy. Their study sites formed a gradient ranging from a natural mixed oak forest to an entirely deforested, urban-agricultural habitat. They looked at the total number of prey items eaten by adults in each study area, and the number of individual snakes that had eaten a given prey species. Body sizes were not different and the diets of both sexes were similar. Snakes living in the more undisturbed habitats ate a greater diversity of prey than snakes in disturbed habitats. Their results demonstrated that habitat alteration by humans drives changes in the composition of the diet of the Aesculapian Snake.

The microhabitats used by the Aesculapian Snake have also been altered by human activity. Lelièvre et al. (2010) found that longissimus used all the anthropogenic structures present in their habitats as refuges, these included: roads, barns, and concrete boards. Despite the low availability of these artificial shelters at their study site, 12% of relocations of radio tracked snakes were using man-made refugia. Their study site lacked large rocks that could provide thermally suitable retreats, and they showed that some artificial refuges had better nocturnal thermal conditions than the available natural shelters. Hiding under roads and covered wood stacks allowed Aesculapian Snakes to maintain higher body temperatures at night than they otherwise could in natural shelters. 

How species responded to past climate change may provide information about how they may respond to changes in the current episode of global warming. Musilová, et al. (2010) examined how the Aesculapian Snake responded to the last global warming event at the Pleistocene–Holocene transition, approximately 5000–8000 years ago using phylogenetic and demographic analyses. The present distribution of this snake in the southern half of Europe is a remnant of a much wider range during the Holocene climatic optimum when populations existed as far north as Denmark. The northern populations disappeared as the climate cooled, and the Aesculapian Snake is now extinct over all of central Europe. The exceptions are a few isolated populations in Germany and the Czech Republic. Musilová, et al. identified two major clades that expanded from their respective western and eastern refugia after the last glacial maximum (18,000–23,000 YA). Snakes from the relictual northern populations were most closely related to the Eastern clade. Thus, the snakes that occupied central and northern Europe during the Holocene climatic optimum were probably derived from the Balkans refugia.  They also identified two small, deep-branching clades: one near the Black Sea, and another in Greece. These clades provided evidence for two additional refugia, which did not successfully contribute to the colonization of central and northern Europe. Their results suggest some populations responded to the mid-Holocene global warming by shifting their ranges further north while other populations of the same species may have been unable to do so. Thus, knowing what populations were able to expand in different species may provide information about what populations will be important for a species’ ability to cope with current and future global warming.

All of this is suggests human altered environments caused changes in the diet, thermal behavior, and geographical distribution of the Aesculapian Snake and that future changes to snake habits can be expected as more human activities change the planet.

Literature
Capizzi, D., M. Capula, L. Rugiero, L. Luiselli. 2008. Dietary patterns of two sympatric Mediterranean snakes (Hierophis viridiflavus and Zamenis longissimus) along a gradient of habitat alteration. The Herpetological Journal 18(3):141-146,

Lelièvre, H., M. Le Hénanff, G. Blouin-Demers, G. Naulleau and O. Lourdais. 2010. Thermal strategies and energetics in two sympatric colubrid snakes with contrasted exposure. Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology 180(3): 415-425

Musilova, R., V. Zavadil, P. Kotlik. 2007. Isolated populations of Zamenis longissimus (Reptilia: Squamata) above the northern limit of the continuous range in Europe: origin and conservation status. Acta Societatis Zoologicae Bohemicae, 71(3-4):197-208.
 

Friday, October 29, 2010

Snakes and Roads

Like many herpetologists, I have spent a considerable amount of time driving roads in search of snakes. Roads can be particularly productive for finding snakes. Since many species are cryptic in their natural habitats - making them difficult to see, most species stand out on roads. Nocturnal species are also relatively easy to see when they are crossing a road because of their reflection in the headlights. Roads have undoubtedly played an important role in the discovery of new knowledge of snakes. But roads are also detrimental to snakes. The Prairie Kingsnake (Lampropeltis calligater) and the Eastern Fox Snake (Pantherophis gloydi) have shown aversions to crossing roads. Roads fragment the habitat, they create edge habitats as the cut through forests, grasslands, and deserts and they may act as barriers for some species. Now, Clark et al. (2010) have demonstrated that even small, recently constructed roads may have a significant impact on the population's genetic structure of some snakes but not others. The authors combined fine-scale molecular genetics with behavioral and ecological data to investigate the impacts of roads on population structure and connectivity. Microsatellite markers were used to characterize genetic variation within and between populations of Timber Rattlesnakes (Crotalus horridus) using dens in regions fragmented by roads. They discovered snake populations that used dens  isolated by roads had  lower genetic diversity and higher genetic differentiation than snakes in hibernacula in contiguous habitat. Snake populations disrupted by roads have fewer matings between populations, than those populations not crossed by roads.  It turns out, roads are extremely effective barriers to gene flow, given how recently they were constructed. Species with a long generation time (10 years), like Timber Rattlesnakes, have been exposed to roads as barriers for a relatively few generations - 7 to 10 generations for the populations studied, and yet their effects can be detected.

R. W. Clark, W. S. Brown, R. Stechert, K. R. Zamudio. 2010. Roads, Interrupted Dispersal, and Genetic Diversity in Timber Rattlesnakes. Conservation Biology, 24:1059–1069.

Varanus bitatawa, A New Monitor Lizard


The Philippines archipelago contains more than 7,100 islands and includes 17 active volcanoes that covers 0.29 million km² in the western Pacific. The archipelago was formed from isolated fragments of continents and islands, some dating back to 30-50 million years ago. Its flora and fauna contain elements from Taiwan, Palawan, and Borneo and show strong affinities with the Sunda Shelf fauna. But the Philippines have a huge endemic fauna, species that are found nowhere else. Historically most of the islands were covered in rain forest, dominated by huge trees of the family Dipterocarpaceae. At higher elevations, montane forests and mossy forests consist mostly of smaller trees; and some areas of the islands contain seasonal forest, mixed forest, savanna, and pine-dominated cloud forest. Thus it is not surprising that the Philippines contain an exceptionally diverse fauna with many still undescribed plants and animals. Luke Welton and colleagues have recently described a new species of giant (2 m), secretive, frugivorous, forest monitor lizard, Varanus bitatawa from the northern Philippines on the island of Luzon. Morphology and DNA data suggest the new species is closely related to Varanus olivaceus, known from southern Luzon and nearby islands. The new species appears to be restricted to forests of the central and northern Sierra Madre mountain range, separating from the range of V. olivaceus by more than 150 km. The name bitatawa is derived from the Agta tribal peoples’ common name for the lizard. The discovery of new large animals is useful for the conservation of the areas they in habitat because it draws attention to biodiversity hot spots and engenders public and political support for protecting biodiversity.

Luke J. Welton, Cameron D. Siler, Daniel Bennett, Avin Diesmos, M. Roy Duya, Roldan Dugay, Edmund Leo B. Rico, Merlijn Van Weerd, and Rafe M. Brown. 2010. A spectacular new Philippine monitor lizard reveals a hidden biogeographic boundary and a novel flagship species for conservation Biology Letters 2010 6:654-658.

A New Night Lizard of the Genus Lepidophyma from Mexico

The Night Lizards (family Xantusiidae) form a small clade of Neotropical lizards that are omnivorous- insectivorous and exceptionally secretive. In some molecular studies the  Xantusiidae form a monophyletic group with Scincidae, Lacertidae, and Cordylidae, the Scincomorpha (Albert, et al. 2009). In another study they form a clade with Scincidae, Gerrhosauridae, and Cordylidae, the Scinciformata (Vidal et al., 2009). Previously, the Night  Lizards had been considered relatives of the geckos, partly due to their fused eye lids that they clean with their tongue, as well as their nocturnal habits. But, Night Lizards are also of interest because some species live in small groups of genetically related individuals, an unusual habit for squamates (see: New Night Lizard Kin Selection Study).

This week Garcia-Vazquez et al. (2010) have described a new species of Lepidophyma, one of four xantusiid genera, from the Sierra Negra in southern Puebla, Mexico. Lepidophyma zongolica is known only from the type locality and distinguished from other members of the genus by a variety of morphological traits including the number of dorsal scales, total of femoral pores, number of the paravertebral rows, number of the toe lamellae and number of gulars. Like most xantusiids the new species lives in crevices between rocks, but this species inhabits remnants of Tropical Evergreen Forest and, to date it has been found only between 94 to 120 m in elevation. While the authors consider the species relative abundant, it was not found in similar microhabitats in agro-ecosystems (croplands or coffee plantations), an indication that L. zongolica may be  sensitive to human disturbance and, that it only occurs in more pristine conditions. The description of this new species increases the number of species in the genus to 19.

Literature
Eva M. Albert, Diego San Mauro, Mario García-París, Lukas Rüber and Rafael Zardoya 2009. Effect of taxon sampling on recovering the phylogeny of squamate reptiles based on complete mitochondrial genome and nuclear gene sequence data. Gene 441(1-2):12-21

Uri O. Garcia-Vazquez, Luis Canesco-Marquez and  Jose L. Aguilar-Lopez. 2010. A new species of night lizard of the genus Lepidophyma (Squamata: Xantusiidae) from southern Puebla, México. Zootaxa 2657: 47–54

Nicolas Vidal and S. Blair Hedges. 2009. The molecular evolutionary tree of lizards, snakes, and amphisbaenians. Comptes Rendus Biologies 332(2-3):129-139

Thursday, October 28, 2010

Longest Snake in Captivity Dies From Cancer

The world's longest snake living in captivity -- a 24-foot python called Fluffy -- has died due to an apparent tumour, say keepers at Ohio's Columbus Zoo. The 18-years-old, 300-pound Reticulated Python apparently held the title of longest snake (in captivity) by Guinness World Records. A necropsy performed at the Ohio State University College of Veterinary Medicine revealed the presence of a mass on her ovary. This snake did not break the record size attained by Collossus at the Pittsburgh Zoo, which reached 28.5 ft.

Tuesday, October 26, 2010

Mississippi Concerned About Burmese Pythons

The following story was posted on the ClarionLedger.com web site today.

Constrictors seen as threat in state
Molly Parker • mparker2@jackson.gannett.com • October 26, 2010

An area lawmaker is eyeing Florida's python problem and wondering if Mississippi should take action to keep nonnative snakes from being released into the wild - intentionally or accidentally."Here comes a tornado, hurricane and these animals get loose, then they're in neighborhoods and somebody's dog, cat or somebody's child gets hurt," said Rep. Earle Banks, D-Jackson. Banks said he doesn't know examples of this happening in Mississippi, "But the point is we don't want this." Banks said he plans to push legislation, as he did last session, that would require the Department of Wildlife, Fisheries and Parks to create a nonnative reptile program and outlaw the release into the wild of snakes and other creatures that are not indigenous to Mississippi. "You can have a 20-foot snake in your house if you want, but what happens if you don't want it? We don't want these reptiles released into the woods and lakes," he said. Banks said he's also working with the Jackson Zoo. But Mississippi snake expert Terry Vandeventer of Byram said Banks' push is fanning panic."We already have a law. The state already has a state regulation of the release of animals into the wild," Vandeventer said. Banks said a ban isn't necessary but wants stricter guidelines on exotic pets. This year, Florida banned individuals from owning Burmese pythons and six other large, exotic reptile species. Pythons have wreaked havoc on delicate ecosystems in south Florida's Everglades National Park. A hunting season was opened last year. In 2009, a Burmese python killed a 2-year-old Florida girl. Human deaths, however, are rare. Justin Ables, owner of The Jungle Exotic Pets and Live Bait in Florence, said he sells a few Burmese pythons "but not a ton." But worrying about Burmese pythons is unwarranted, he said."Here in the wild, they are not going to breed," Ables said. Research is mixed on whether pythons could breed in central Mississippi. A 2009 U.S. Geological Survey on nine constrictor snakes found most of Mississippi, excluding the northern tip, to be a potentially suitable habitat for the Burmese python, said Gary Ervin, associate professor of biological sciences at Mississippi State University."These things represent a predator that we just don't have here and a potentially serious ecological threat because it would be something our native species simply would have no adaptation for dealing with," said Ervin, who studies the impact of nonnative plants on the ecosystem. But Vandeventer, who travels to schools and other venues for snake education, said the study has been disproven "over and over again by reputable scientists. "He (Banks) has been influenced by this shock stuff and that's very clear," Vandeventer said. This winter's freeze killed most of the Burmese pythons in the Everglades, he said, and they wouldn't make it through a Mississippi winter. Ervin also doubted the python's chances to flourish here, and pointed to another paper published this year that followed the success of Burmese pythons in South Carolina. "They found that ones that didn't burrow and try to hibernate died by freezing temperatures," he said. Still, Ervin said he supports Banks' initiative. "I think those sorts of laws are certainly helpful, and there are cases where I wish we had more of that legislation dealing with invasive species in general," he said.As an example, Ervin mentioned Kudzu, a problematic plant in young pine plantation and for utility companies, yet introduced by humans with good intentions decades ago to stabilize the soil and as a cattle forage. Wendy Purvis, owner of The Fish Bowl in Ridgeland, said she doesn't keep Burmese pythons in her store. But Purvis said she will order them for responsible snake handlers.Otherwise, Purvis said she educates people who don't understand what they're getting into. "The snake gets 20 feet long. You have to have a dedicated room and quite a bit of money. They're expensive to feed, and you'll eventually have to move to rabbits," she said. Purvis said putting regulations on the books about how to handle an unwanted snake is a good idea. "They won't survive that first winter," she said. "It would be just like leaving a cat behind when you move for someone else to take care of."

Indian Fossil Snakes and Old Tropical Rainforests


Snakes from the Eocene of India were diverse. Jean-Claude Rage (2002) reported on the early Eocene serpent fauna of India using fossils from the Panandhro Mine in northwestern India. This locality produced a rich snake fauna that was dominated by the highly aquatic palaeophiids. Rage found three families represented in the fossil beds: the aquatic Palaeophiidae; fossils that may be ?Madtsoiidae or Boidae; and a representative  of the Colubroidea. The Palaeophiidae include remains of two species: Pterosphenus kutchensis and Pt. biswasi .They are the earliest known representatives of the genus. Madtsoiidae (or Boidae) were represented by two specimens that do not permit distinction between these two families. If the fossils belong to the Boidae, they would be the earliest representatives of that family in Asia. And the colubroid snake from this site ranks among the earliest Cenozoic representatives of the clade. The possibility that it belongs to the Colubridae could not be eliminated – it had a very light build. If true it would be the earliest known snake in the family Colubridae. Nearly all fossil specimens at the mine belonged to Pterosphenus, a highly aquatic genus. It lived in shallow water, probably in marine environment close to the coasts or in freshwater. In a second paper, Rage and colleagues (2008) reported on a second India early Eocene fossil site, the Vastan Lignite Mine in Gujarat, western India. The fossils included at least 10 species that belong to the Madtsoiidae; Palaeophiidae (Palaeophis and Pterosphenus); Boidae; and several Caenophidia.  The Colubroidea were represented by Russellophis crassus. (Russellophiidae) and by Procerophis sahnii. As well as Thaumastophis missiaeni a caenophidian of uncertain family status. The authors write, “The number of taxa that represent the Colubroidea or at least the Caenophidia, i.e., advanced snakes, is astonishing for the Eocene. This is consistent with the view that Asia played an important part in the early history of these taxa.”  The Vastan Mine fossils come from marine and continental levels and includes highly aquatic, amphibious, and terrestrial snakes. The composition of the fauna from Vastan seems similar to that of the more poorly known early Eocene of Europe.

Also consider the recent discover of Sanajeh indicus by Wilson et al. 2010. Sanajeh was  from the very late Cretaceous and found near Dholi Dungri village in Gujarat, Western India. Sanajeh indicus was preserved in a sauropod dinosaur nesting ground associated with eggs and a hatchling sauropod. The new fossils provided the first evidence of snake predation on hatchling dinosaurs.

Thus the time span between late Cretaceous and the early Eocene of India appears to have been rich is snake species. Today there is evidence to suggest that India had the oldest tropical forests known during this time. Rust et al. (2010), describe the Cambay amber of Gujarat, in western India and fossilized wood as the oldest evidence for tropical forests in Asia. The amber has been chemically linked to dipterocarps (Dipterocarpaceae), a family of hardwood trees that today make up 80 percent of the forest canopy in Southeast Asia. The fossilized wood from this family makes this deposit the earliest record of these plants in India and demonstrates that the family is nearly twice as old as was commonly believed. The forest was like to have been present when portions of the southern supercontinent Gondwana were still connected. The paper also describes 100 species of arthropod representing 55 families and 14 orders. Some of these species are early relatives of highly social, or eusocial, insects like honey bees and stingless bees, rhinotermitid termites, and ants, suggesting that these groups radiated during or just prior to the early Eocene. Many of the Cambay fossils have relatives on other continents—although not where it would be expected. Rather than finding evolutionary ties to Africa and Madagascar, landmasses that India had most recently been linked to as part of Gondwana, the researchers found relatives in Northern Europe, Asia, Australia, and the Americas.

References
Rage J.-C., Bajpai S., Thewissen J. G. M. & Tiwari B. N. 2003. — Early Eocene snakes from
Kutch, Western India, with a review of the Palaeophiidae. Geodiversitas 25 (4):695-716.

Rage, J.-C., A. Folie, R. S. Rana, H. Singh, K. D. Rose, T. Smith. 2008. A Diverse Snake Fauna from the Early Eocene of Vastan Lignite Mine, Gujarat, India. Acta Palaeontologica Polonica, 53 (3):391-403.

Rust, J., H. Singh, R. S. Rana, T. McCann, L. Singh, K. Anderson, N. Sarkar, P. C. Nascimbene, F. Stebner, J C. Thomas, M. S. Kraemer, C. J. Williams, M. S. Engel, A. Sahni, and D. Grimaldi 2010. Biogeographic and evolutionary implications of a diverse paleobiota in amber from the Early Eocene of India. PNAS published ahead of print October 25, 2010, doi:10.1073/pnas.1007407107

Wilson J. A., Mohabey D,M., Peters S.E., Head J.J.  2010. Predation upon Hatchling Dinosaurs by a New Snake from the Late Cretaceous of India. PLoS Biol 8(3): e1000322. doi:10.1371/journal.pbio.1000322

Monday, October 25, 2010

Snakebite, Snake Activity and Climate

Climate has a far reaching impact on organisms, including snakes, like the Coastal Taipan to the left.. The Queensland news media are carrying numerous stories warning people about an increased risk of snakebite. Most recently Jodie Wilson, President of the Australian Veterinary Association of Queensland said yesterday (October 22, 2010) that veterinarians were expecting more envenomations in the coming weeks due to snakes being flushed out by torrential rain and dog owners walking dogs off-leash was apparently exacerbating the number of bites. But more importantly, the number of snakes encountered by pets and humans appears to have increased because of increased rainfall in a La Niña year. Northern and eastern Australia tends to have below normal temperatures during La Niña phase years and the cooling is most extreme from October to March. In contrast, temperatures are much warmer during El Niño years. El Niño occurs when sea surface temperatures in the central to eastern Pacific Ocean are significantly warmer than normal. This recurs every three to eight years and is associated with a strong negative phase in the Southern Oscillation pendulum. In most years (the normal pattern) the Humboldt Current brings  cold water northward along the west coast of South America, a pattern that is enhanced by deep cold water ‘upwelling’ along the Peruvian Coast. The trade winds push the colder water westward and as it flows westward along the equator it picks up heat. The result is the western Pacific is 8 to 10 C warmer than the eastern Pacific. In El Niño years, the normal cold water flow along the South American coast and in the eastern Pacific weakens or may even vanish completely, and the central and eastern Pacific may become almost as warm as the western Pacific. When the eastern Pacific Ocean is much cooler than normal the air rising over the normally warm seas cause moist air to rises higher in the atmosphere causing abundant rainfall over the over eastern and northern Australia, resulting in widespread rain and flooding to Australia – this phase is called La Niña. Thus, the Australia Broadcasting Company is now reporting the wettest September on record for Queensland. Snakes are flooded out of their retreats and move to higher ground.

But the El Nino-La Nina cycle does not only effect snakes and snakebite in Australia. Morrison and Bolger (2002)  monitored reproductive success of individual rufous-crowned sparrows (Aimophila ruficeps) in coastal sage scrub habitat of southern California from 1997 to 1999. They found annual reproductive output of this ground-nesting bird varied strongly with annual variation in rainfall. Birds fledged 3.0 young per breeding pair in 1997, when rainfall was near the long-term mean, 5.1 offspring per pair in 1998, a wet El Niño year. But in the drier 1999 La Niña year  only 0.8 fledglings were produced per pair. The reproductive output was consistent with the hypothesis that food availability was positively correlated with rainfall. But, the factor most responsible for the high reproductive output in 1998 was low early season nest predation which, combined with favorable nesting conditions, enabled more pairs to multiple-brood. Cool, rainy El Niño conditions in 1998 altered the activity of snakes, the main predator of these nests. The authors used video-surveillance of nests and found the California Kingsnake (Lampropeltis getula californiae) and the San Diego Gopher Snake (Pituophis melanoleucus annectens) were the principal nest predators and that they account for 90% of the predation events, where the predators could be identified. More recently, González-Andrade and  Chippaux (2010) evaluated the burden of snake bite in Ecuador in an attempt to identify the difficulties of snake bite management in the country's health facilities. They surveyed national health statistics to estimate the overall incidence and mortality due to snake bites. From1998–2007, the average annual incidence and mortality was respectively 11 and 0.5 per 100 000 inhabitants. The Ecuadorian snakebite incidence increased in the rainy season and in El Niño years. Snake activity changes with cllimate, a simple concept but one with far reaching consequences that are seldom appreciated.

Literature
Morrison, S. and  D. Bolger. 2002.  Variation in a sparrow's reproductive success with rainfall: food and predator-mediated processes. Oecologia 133: 315-324.

González-Andrade, F. and  J.-P. Chippaux. 2010. Snake bite envenomation in Ecuador. Transactions of the Royal Society of Tropical Medicine and Hygiene, 104:588-591.

Sunday, October 24, 2010

Massasauga Envenomations and Conservation

Conservation of venomous snakes can be a hard sell to a public that is fearful and despises snakes. The rattlesnake genus Sistrurus contains two species, one of which, the Massasauga (S. catenatus), is considered endangered over much of its distribution in the eastern North America. The Massasauga is perhaps the most studied snake on the planet and journals are filled with numerous recommendations for its conservation which range from road signs alerting motorists to its presence and under pavement tunnels, to altering footpaths through parks and collecting the last remaining specimens from a population for captive breeding. Legislation to protect such species is an effort but rarely does it change people's behavior. In many places Massasaugas are found near human habitations, usually because developers built the houses in snake habitat, such as drained wetlands, floodplains, or savannas with existing populations of snakes. In these areas humans tend to be a major source of snake mortality. Even though snake populations in these suburban areas tend to be low snakes are often killed by traffic or fearful humans and collected for the pet trade. Gravid females are often the most obvious snakes in the population because they tend to thermoregulate more frequently to maintain optimal temperatures for their embryos. This morning (Sunday, October 24, 2010) the Chicago Tribune is carrying an AP story that suggests Massasauga envenomations are increasing in Lower Michigan. Rattlesnake bites which are usually rare have apparently increased (nobody is keeping track of the numbers), but bites have been reported in: Orion Township, Highland Recreation Area, and Flushing; Spring Harbor Township. Additionally Poison Control at Children's Hospital of Michigan reports at least four bites this year. The increased number of envenomations is being attributed to warmer weather that has lasted into the autumn. It seems likely that the snakes have not only remained active longer, but that people may be spending more time outdoors. This is not good news for the efforts to conserve the snake. It is somewhat ironic that the very first attempt to make an animal resistant to snake venom was done by Henry Sewall, working at the University of Michigan in 1886–1887. Sewall used Pigeons and venom from the Eastern Massasauga (Sistrusus c. catenatus) also known as the "swamp rattler" to demonstrate that organisms could be made resistant to venom. Sewall injected small doses that were gradually increased until the birds could withstand 10 times the lethal dosage. These experiments were the stimulus for developing other antitoxins, not only for snakebites, but for other diseases that resulted from bacterial toxins like diphtheria.

Thursday, October 21, 2010

Singapore Pythons and Snakebites


AsiaOne is reporting a story (October 20, 2010) that describes the presence of two pythons in the past few days in Bendemeer and Tanjong Pagar, alarming passers-by such as information- technology executive C. H. Seah. Last Saturday, the 42-year-old noticed a group of construction workers causing a commotion at a canal in Bendemeer's St George Lane, and so walked up to take a closer look. To his shock, he discovered that they were crowding around a 4m-long python. He sent a photograph of the reptile to citizen-journalism website Stomp. Another python was spotted yesterday outside Tanjong Pagar's Bestway Building in Prince Edward Road. The frightened animal almost bit a man who tried to catch it. Mr Biswajit Guha, Director of Zoology at the Singapore Zoo, advised the public to avoid approaching wild snakes, especially if they appear to be weak, injured or disoriented.

The Wildlife Reserves Singapore (WRS) take the urbanized snakes and put them in quarantine and do health evaluations, some may be micro-chipped, rehabilitated and released back into the wild. WRS has received 127 snakes so far this year, including those confiscated by the Agri-Food & Veterinary Authority. "Snakes prefer thickly planted areas or quiet dark corners," Mr Guha said. "It would be best to keep residential and public areas clear of clutter so that there are no hiding places for them." A spokesperson for Animal Concerns Research and Education Society the society receives about 60 calls each month about snake sightings.

Singapore pythons are of course Broghammerus reticulatus, a species that has become adapted to urbanized environments, living in drains and sewers, feeding on other human commensals. Pythons are apparently a very minor medical hazard to Singapore residents. (Tan 2010) reported  four python bites that were treated in a Singapore hospital over 5 years. The need for surgical intervention in python bites is usually minimal with drainage of abscess and wound debridement for necrotic tissues. However, over the 5 year study period 35 definite snake bites were reported, and the hospital saw another 17 patients that were suspected of sustaining snake bites. None of the bites were from captive snakes, but five bites were sustained while the person was attempting to capture the snake. Most of the snakebites documented showed pain and swelling. Systemic manifestations were generally mild and not all the symptoms are due to systemic envenomation. There were a number of cases of definite and probable snakebites where there was minimal local injury and no systemic effects despite the presence of fang marks (7/26 or 27%). These could be cases of dry bites or bites by a non-venomous snake. Dry bites occur when there is no envenomation despite actual bite by a venomous snake. None of the people who presented with snakebite over the five year period died, and most recovered without additional problems. The island nation is very well developed, but despite the small amount of available habitat the island supports three species of pit vipers, seven species of terrestrial elapids, eleven species of sea snakes - all capable of delivering venom. The total number of snakes reported from the island and surrounding waters is about 75 species.
 
Tan, H. H. 2010. Epidemiology of snakebites from a general hospital in Singapore - a 5-year retrospective review (2004-2008).  Ann. Acad. Med. Singapore 39:640-7.

Tuesday, October 19, 2010

Timber Rattlesnake Conservation in Connecticut


Crotalus horridus


The presence of rattlesnakes is a reminder that America has wild places. Unlike many of the natricids (garter snakes, water snakes, brown snakes)  that common and are often present in urbanized habitat, rattlesnakes often survive better in places with lower human populations. To be sure humans have altered the habitat at times so that rattlesnakes are favored. Cutting old growth forests that offered minimal basking opportunities resulted in increased rattlesnake populations in many areas of the eastern US. At times this resulted in bounties being placed on the pit vipers, and extirpation sometimes followed.

Thus it is welcome news that a well developed eastern state, in this case Connecticut, are interested in protecting remaining populations of timber rattlesnakes. Peter Marteka of the Hartford Courant (October 19, 2010) reports that the town of Glastonbury, CT received a $180,000 grant from the state Department of Environmental Protection to buy the Tiboni property, a 55-Acre parcel in the town's eastern highlands. Connecticut law prevents people from trapping or killing snakes, and most snake mortality these days is from traffic. "This whole area is prime rattlesnake country," town planner John Rook said. "One of the town's goals has been to piece together properties and protect a large, unfragmented area, especially in this part of town." The local, state and the federal governments, as well as groups like the Nature Conservancy, have targeted the 17,500-acre Meshomasic highlands in central Connecticut as an area to be preserved. The highlands run through Bolton, East Hampton, Glastonbury, Hebron, Marlborough and Portland. It seems unusual, but when development has been proposed near a snake habitat, Glastonbury has enforced its strict guidelines that protect the snake's denning and foraging areas. Developers are required to hire herpetologists, educate homeowners about the snake, and limit work to winter, when snakes are hibernating. "It's not only the snakes, but there are neotropical songbirds that thrive in the unfragmented forest areas," Rook said. "These properties have been on the radar screen for a long time and have been a priority for years."