Christopher Bock, Natural Resource Conservation
Jonathan Eckerson, Natural Resource Conservation
Lisa Fossa, Animal Science
Salamanders are vertebrates that have evolved over the last 150-200 million years to be very ecologically diverse (Davic & Welsh, 2004, p. 405). There are over 400 species in 59 genera and 10 families spread around the world, 234 of these are found in North America (p. 405). Of the 234 species of salamander found in North America, 67 (29%) are listed as imperiled or critically imperiled (p. 405).Salamanders play a crucial role in forest ecosystems and make up a high percentage of forest biomass. In the Mark Twain National Forest in Missouri, it was estimated that across an area of 275580 ha (2755.8 km2), there were 1.88-2.65 billion salamanders that made up 1485.2–2093.5 metric tons (mt) of wet biomass (Semlitsch, O’Donnell, & Thompson, 2014, p. 1003). In the Hubbard Brook experimental forest of New Hampshire, it was estimated that five salamander species had a combined average density of 2950 salamanders/ha (0.29/m2) and a biomass of 0.00177 mt/ha wet weight, which was 2.6 times the combined wet-weight biomass of all birds in the watershed at the peak of breeding season and at the very least equal to that of small mammals (Davic and Welsh, 2004, p. 407). Salamanders are also an abundant source of energy and nutrients for birds, fish, reptiles, mammals, and decomposers (p. 421). Salamanders play the role of a voracious predator and keep arthropod populations in balance (Why Salamanders Matter, n.d.). They are considered “keystone predators”, meaning they prevent dominant prey from monopolizing limited resources, thus providing balance to the ecosystem. The role they play has a disproportionately large effect on the ecosystem relative to their abundance (p. 417). This role salamanders play as keystone predators is critical in the trophic processes at the leaf litter-soil interface in temperate forest ecosystems. And with soils globally being the third largest carbon pool, the key role salamanders play in maintaining this healthy ecosystem cannot be understated (Best & Welsh, 2014, p. 16). Salamanders are also exceptional indicators of environmental health as their skin is moist and permeable, meaning that they are vulnerable to toxins and droughts (United States Geological Survey, 2017). Salamanders are incredible vertebrates that play a crucial role in the forest ecosystems that make up Amherst. Apparent by their enormous densities and high species richness in North America, Salamanders play a significant role in maintaining healthy forests and have evolved over millions of years to do so (Best & Welsh, 2014, p. 15).
Given that salamanders play such a pivotal role forest ecosystems, the numerous threats that they face is alarming. It comes as no surprise that one of the underlying causes of threatened salamander populations is climate change. Physiological adaptations such as shifts in growth rates in ectothermic salamanders (ectothermic organisms depend on external sources to regulate their internal body temperature) have occured due to climate change. Over a 55 year period in the Appalachian Mountains of New York, five salamander species saw an 8% reduction in the average adult body size (Caruso, Sears, Adams & Lips, 2014, p. 1758). With increasing external temperatures there is a decrease in activity rates, leading to reduced foraging and thus reduced growth. Salamanders with decreased body size are then more susceptible to issues breeding (p. 1758). Salamanders depend on water bodies to breed, however, climate change will see a decrease in precipitation and an increase in droughts. Chandler, Rypel, Jiao, Haas and Gorman (2016), found that breeding conditions for salamanders would become unsuitable in the future due to a decrease in precipitation and an increase in drought (para. 1). From 1993 to 2014, wetland hydroperiods (a period of time during which a wetland is covered by water) in the southeastern US decreased by 36% in duration (Chandler, Rypel, Jiao, Haas & Gorman, 2016, para. 30). Factors such as this leads to unsuitable breeding conditions and a shift in the timing of salamander breeding (para. 18). During a drought in the Cascade Mountains of Oregon, salamander size was an average of 15.8% smaller than in the previous year without a drought (Kaylor, VerWey, Cortes, 2019, p. 58). There is also increased displacement due to severe weather events occurring more regularly as a result of climate change (Deitchler, Davenport & Lowe, 2015, p. 239). Climate change presents many challenges for salamander and it’s an ever increasing problem. However, we cannot stop climate change at a town level. In order to mitigate the effects of climate change on salamanders, an increase in amphibian road crossings and land protection is needed in order to drop salamander mortality and connect breeding areas.
Salamanders are also under enormous threat through habitat fragmentation due to human caused factors such as roads and development. The primary threat to many species of salamanders in Amherst is the loss of habitat through development, logging, and other human activities. The Massachusetts Audubon reported that from 2005 – 2013, an average of 13 acres a day were lost to development in Massachusetts and over 50,000 acres of forest were lost during that time frame (Massachusetts Audubon, 2013).
For 500 breeding pools assessed in central and western Massachusetts, the median road mortality rate was estimated to be 17% annually for salamanders moving 100 m and 37% for salamanders moving 500 m. According to Gibbs and Shriver (2005), road mortality >10-20% could lead to the expiration of local salamander populations in many areas (Gibbs & Shriver, 2005, p. 288). Roads seeing traffic of over 1000 cars per day can be absolutely detrimental to populations, and with many roads in Amherst seeing over 1,000 vehicles a day, some even up to 23,000, this is a serious issue (Town of Amherst, 2007, p. 2; Gibbs & Shriver, 2005, p. 288).
With this severe habitat fragmentation occurring through habitat loss and road mortality, local populations become subject to loss of gene flow, inbreeding depression, and thus even expiration of the population. Populations of red-backed salamanders sampled from both fragmented and contiguous landscapes have shown the effects of habitat fragmentation, with the populations in the contiguous habitat showing far greater genetic diversity than those in fragmented habitat (Noël, Ouellet, Galois & Lapointe, 2006, p. 604). For red-backed salamanders, genetic diversity is highly correlated with fitness. This is especially true in regards to the salamanders having the ability to adapt to the changing environment (p. 604). Roads create barriers to breeding areas via high salamander mortality and unpassable structures while development results in severe habitat loss.
With the important role salamanders play in forest ecosystems, there would be catastrophic negative impacts that would occur with their removal. There would be a loss of balance and undoubtedly a negative domino effect throughout forest ecosystems. The forests of Amherst would become degraded and even more vulnerable to the impacts of climate change. The health of forest and wetland ecosystems also contribute billions of dollars to the economy by supporting industries such as fishing and timber, as well as recreation (USGS, 2017).
Our proposal is to mitigate the threats of climate change on salamanders by increasing the connectivity of salamander breeding areas through land protection and the building of more tunnels. These tunnels provide solace for the salamanders during the first warm spring rain, it serves as the main highway to reach the vernal pools. Conservation and protection of these salamanders is crucial when considering the benefits they apply for the Amherst ecosystem. While climate change will certainly impact not just salamanders, but for all life and Amherst has a huge reason for trying to put focus on the salamander crossing tunnels that have already been constructed.
The town of Amherst is already home to the first tunnel system designed to help salamanders reach the vernal pools that they breed in each spring. These first two tunnels were an experimental design funded by the British Fauna and Floral Preservation Society and the ACO Polymer in Germany. They were built in 1987 on Henry Street and sit 200ft apart from each other. They are currently maintained by the Hitchcock Center with the help of volunteers, who work to keep the tunnels clear from debris and perform general maintenance on them each year (Henry Street Salamander Tunnels, Hitchcock Center for the Environment, n.d). With the success of these tunnels, more have been built in other communities and studies have been done to prove the effectiveness of the already existing salamander tunnels in Amherst. (Hedrick, Linden, Cordero, Watt, O’Roark, Cox, & Sutherland, 2019). Jackson (1996, p. 3), reported that 75.9 percent of the animals that reached the entrance to the tunnels successfully passed through them. It was found that with an increase in ambient light to the tunnels through perhaps grating in the road, a higher percentage of salamanders would pass through the tunnels. With the already strong community in Amherst dedicated to helping the salamanders reach the areas they need to in order to breed and the building supplies that are already donated for the yearly maintenance, we have a strong foundation in place for improvement. Helldin and Petrovan (2019) found that at all road sites with salamander mortality mitigation structures in place there was a decrease in mortality. The number of salamanders saved per night varied between 25 and 200 individuals (p. 6). We as a community have the dedication, support, and materials necessary to renovate the already existing tunnels so they are up to the current standards.
How do we propose we make that happen? By focusing more on the development and expansion of the current tunnel, we can have a direct positive impact on salamander populations since there will be more pathways to the vernal pools and current tunnels will have less traffic. With this method, more salamanders are able to safely migrate from upland areas to the vernal pools and with a higher success rate of reaching the vernal pools, more female salamanders will be able to reproduce and add to the total count of local Amherst salamanders. Tunnel success rates for Amherst salamanders is shown to improve for the years 2016 to 2018 (Hedrick, Linden, Cordero, Watt, O’Roark, Cox, & Sutherland, 2019). In 2016, a total of 124 salamanders were counted and the tunnel success rate was 11.3% (also includes fence climbers) and 20.6% for salamanders who reached the tunnels. In 2017, 108 salamanders were counted with a success rate of 13.9% and 21.1% of the salamanders who reached the tunnels had used them correctly. 25% of the salamanders had used the lit tunnel while 14.8% of salamanders used the dark tunnel. In 2018, a total of 357 salamanders were counted, only 8.9% had reached the tunnels and used them successfully. The construction of these tunnels can be recognized as an effective way to benefit the population of salamanders, seeing as it provides assistance to salamanders who would otherwise get run over by the flowing traffic above. When looking at the current results of the number of salamanders that were able to successfully cross using the salamander crossing tunnels, it is evident that the tunnels are beneficial for already existing salamander populations. Considering that these tunnels were built in 1987, a control mechanism for making it so these tunnels provide the maximum amount of effectiveness for helping boost the population, building more tunnels could prove to work.
Also, when looking at the 2017 recorded data, it is evident that salamander crossing success rate was more successful for the lit tunnels opposed to the dark tunnels, so we can determine that the salamanders are more likely to succeed in crossing under the road when using a lit tunnel. From the results, the “light at the end of the tunnel in 2017” hypothesis is because salamanders are attracted to artificial lighting since “glow sticks increased the average number of captures of spotted salamanders by more than three times, Jefferson salamanders by nearly four times” (Jeff Mulhollem. 2017). A team of researchers at Penn State found that “glow sticks — cheap, self-contained, short-term light-sources — attract the creatures to traps set in vernal pools where they come to reproduce in the spring.” (Jeff Mulhollem. 2017.) The use of artificial lighting combined with the tunnels for salamander crossing could equal maximum efficiency for salamander success rate. Expansion of the already existing tunnel blueprint could certainly be negotiated through the Hitchcock Center, and with the help of volunteer work plus the cost of materials for expansion could prove to be both feasible and effective when it comes to protecting salamander populations from the effects of climate change, salamander resting grounds could also be another control mechanism for protecting salamanders from the harsh elements.
Along with the addition of more tunnels, protecting land surrounding the crossing tunnels to ensure their success is a crucial part of our proposal. Policy in Massachusetts focuses on protecting breeding sites for salamanders, and while that’s important, upland habitat areas that are slightly higher in elevation and do not have water above ground also need to be protected (McGarigal, Compton & Gamble, 2008, p. 25). If breeding sites are protected but surrounding upland habitats are not, the breeding sites are susceptible to becoming isolated and thus less productive (p. 25). There is also a positive relationship between the amount of forest surrounding a breeding site and the presence of species such as the Spotted and Jefferson Salamanders, meaning protecting forest is crucial (Porej, Micacchion & Hetherington, 2004, p. 406). The purchase of Eastman Lot, owned by the Cowls, by the town of Amherst would go a long way towards conserving land important to salamanders. Protecting land surrounding the tunnel crossings would eliminate the risk of development and ensure that there is healthy upland forest allowing the salamander populations to flourish.
The problems that people could have with our proposal include the necessary money and support required to make it successful. The maintenance of the existing tunnels is funded, but asking for more money from donors or finding new potential donors to construct new tunnels is asking a lot. The original tunnels required substantial funding from both the British Fauna and Floral Preservation Society and the ACO Polymer in Germany (Henry Street Salamander Tunnels, Hitchcock Center for the Environment). With all of the current maintenance being done by volunteers, it’s going to be incredibly difficult to gather even more volunteers in order to construct new tunnels and then continue to provide yearly maintenance to the new and existing tunnels. Raising awareness will help bring in volunteers but with the majority of the construction and maintenance needing to be done over the winter getting people will be difficult. Not many people care enough about the salamander population to do manual labor during the harsh New England winter.
Salamanders play an irreplaceable role in forest ecosystems and their continued success in playing this role depends on us. With the important role that forests play in sustaining a healthy environment, Amherst must give direct attention to the issue of salamander protection. Development and connectivity poses numerous threats to salamander populations within the town of Amherst, Massachusetts. On top of this, climate change is an increasing threat to salamanders. With increased connectivity of upland areas to breeding areas through adding more amphibian road crossing tunnels, salamander mortality can be greatly reduced during migration. Protecting the land surrounding the crossing tunnels allows more insurance towards the continued success of these tunnels and eliminates the threat of development. Together, these methods will help stem the threat that climate change poses on salamanders and it puts them in the best position to succeed through adapting.
Gibbs, J. P., & Shriver, W. G. (2005). Can road mortality limit populations of pool-breeding amphibians? Wetlands Ecology and Management, 13(3), 281–289. doi: 10.1007/s11273-004-7522-9
Town of Amherst. (2007). Planning Amherst Together. Planning Amherst Together. Amherst, MA.
Fast Facts. (2013). Retrieved November 17, 2019, from https://www.massaudubon.org/our-conservation-work/advocacy/shaping-the-future-of-your-community/publications-community-resources/losing-ground-report/fast-facts.
Noël, S., Ouellet, M., Galois, P., & Lapointe, F.-J. (2006). Impact of urban fragmentation on the genetic structure of the eastern red-backed salamander. Conservation Genetics, 8(3), 599–606. doi: 10.1007/s10592-006-9202-1
Saving Salamanders: Vital to Ecosystem Health. (2017, December 12). Retrieved November 17, 2019, from https://www.usgs.gov/news/saving-salamanders-vital-ecosystem-health.
Semlitsch, R., O’Donnell, K., & Thompson, F. (2014). Abundance, biomass production, nutrient content, and the possible role of terrestrial salamanders in Missouri Ozark forest ecosystems. Canadian Journal of Zoology, 92(12), 997–1004. doi: 10.1139/cjz-2014-0141
McGarigal, K., Compton, B. W., & Gamble, L. (2008). Marbled Salamander (Ambystoma opacum) Conservation Plan for Massachusetts.
Porej, D., Micacchion, M., & Hetherington, T. E. (2004). Core terrestrial habitat for conservation of local populations of salamanders and wood frogs in agricultural landscapes. Biological Conservation, 120(3), 399–409. doi: 10.1016/j.biocon.2004.03.015
Brandon P. Hedrick, Abby Vander Linden, Samantha A. Cordero, Edward Watt, Patrick M. O’Roark, Samantha L. Cox, Christopher Sutherland. (2019). Keeping salamanders off the streets: Evaluating one of the first US amphibian road tunnels 30 years later. bioRxiv 569426; doi: https://doi.org/10.1101/569426.
Jackson, Scott & Griffin, Curtice & Griffin, C. (1998). A Strategy for Mitigating Highway Impacts on Wildlife. Proceedings of the International Conference on Wildlife Ecology and Transportation.
Davic, R. D., & Welsh, H. H. (2004). On the Ecological Roles of Salamanders. Annual Review of Ecology, Evolution, and Systematics, 35(1), 405–434. doi: 10.1146/annurev.ecolsys.35.112202.130116
Why Salamanders Matter. (2018, March 16). Retrieved from https://www.savethesalamanders.com/why-salamanders-matter/.
Best, M. L., & Welsh, J. H. H. (2014). The trophic role of a forest salamander: impacts on invertebrates, leaf litter retention, and the humification process. Ecosphere, 5(2). doi: 10.1890/es13-00302.1
Caruso, N. M., Sears, M. W., Adams, D. C., & Lips, K. R. (2014). Widespread rapid reductions in body size of adult salamanders in response to climate change. Global Change Biology, 20(6), 1751–1759. doi: 10.1111/gcb.12550
Chandler, H. C., Rypel, A. L., Jiao, Y., Haas, C. A., & Gorman, T. A. (2016). Hindcasting Historical Breeding Conditions for an Endangered Salamander in Ephemeral Wetlands of the Southeastern USA: Implications of Climate Change. Plos One, 11(2). doi: 10.1371/journal.pone.0150169
Deitchler, E. A., Davenport, J. M., & Lowe, W. H. (2015). Homing behavior of the northern spring salamander, gyrinophilus porphyriticus, in a northeastern united states headwater stream. Herpetological Conservation and Biology, 10(1), 235-241.
Kaylor, M. J., VerWey, B. J., Cortes, A., & Warren, D. R. (2019). Drought impacts to trout and salamanders in cool, forested headwater ecosystems in the western cascade mountains, OR. Hydrobiologia, 833(1), 65-80. doi:10.1007/s10750-019-3882-2