The value of amphibians to humans is not widely perceived, despite presenting many compelling reasons for their conservation - Meredith et al. (2016)
A key message I hope to deliver is that despite their size in stature, amphibians and reptiles are far more important than is appreciated or understood. These little vertebrate creatures are so abundant in wetlands and in soils that they cumulatively support many of the planets climate systems. They support the natural resource economy in very significant ways. So my interest in herpetology (amphibians and reptiles = herps) is more than an amusement. I am interested in them from a scientific point of view, because they are ecologically and behaviorally fascinating.
One of my biggest concerns is that amphibians and reptiles are not being valued properly. This is creating issues for their populations, which are in endless retreat. There is no end that is being planned to end the retreat of these creatures from water and land. Another piece of land is removed with each new land development, another resource road cuts into the wetland to forest migration corridor, and the climate warms to reduce the amount of suitable habitat area. What is the limit to this retreat? How much and why should we value of amphibians? The answer to this question is what ultimately drives a large part of my research aspirations and advocacy for conservation.
The standard economists need to learn more about the value and importance of ecosystems, including the organisms that are employed by the sum of their work. Amphibians are working. They are in motion as they filter sediments in wetlands, feed on forest soil insects and dig around the soils, migrate from wetlands into animal burrows where they sometimes perish and decompose, and they symbiotically transport creatures in their skin, including algae, fungi, and bacteria. Hocking and Babbitt (2014), Valencia-Aguilar, Cortés-Gómez, & Ruiz-Agudelo (2013), and West (2018) provide an introduction into the many different types of ecosystem services that herps provide, but discovery of new ecological functions continue.
Cool Amphibian Factoids
Did you know that amphibians regulate mosquito populations to control the spread of human disease (DuRant & Hopkins, 2008; Naz et al. 2019; Rubbo, Lanterman, Falco, & Daniels, 2011)?
Did you now that amphibians transport and subsidize a large volume of minerals and nutrients from wetlands into forests and agricultural area and vice-versa (Capps, Berven, & Tiegs, 2015; Fritz & Whiles, 2018).
Important long-term ecological studies in the 1970 revealed shocking details into the contributions that amphibians provide in forested landscapes. The measures that researchers gathered on their total biomass and energy storage was completely unexpected. Burton & Likens (1975) had discovered that the biomass of Appalachian salamander populations reigned supreme a per-area by weight measurement among vertebrates.
To give some idea on the scale of contributions that amphibians provide, researchers measured and calculated caloric counts and contributions in Appalachian salamanders on a per area scale greater than the annual average human harvest of the world’s marine fishery (Davic & Welsh, 2004):
Recent studies have identified an even greater biomass and larger role of salamanders in retention of carbon in forest soils and cycling of nutrients (Semlitsch, O’Donnell, and Thompson, 2014). Some scientists (see Davic & Welsh, 2004) have reasoned that global decline in amphibians may be significant enough to explain climate change!
The scale of effect from the actions of amphibians is no trivial matter. Even though there is little information on population sizes, one of our local species here in Prince George, BC - the Western Toad - can lay up to 12,000 eggs per female! The massive number of tadpoles would suggest that their numbers are in the billions spread across the North American landscape. Gaining insight into population numbers of Western Toads and other amphibians is one of the goal of my research and conservation efforts, but this is challenging in northern environments where the seasons are short, sometimes chaotic, and the pulses of amphibian surface activity can be brief.
If we can measure population sizes, then we can translate this into indices of biomass, energy, and other contributions to ecosystem functions. Much like keystone species, ecosystem engineers have very important roles in the economy of nature. Ecosystem engineers "...are organisms that directly or indirectly modulate the availability of resources to other species, by causing physical state changes in biotic or abiotic materials" (Jones Lawton, and Shachak 1994).
Financial gains and job creation within natural resource economies are ultimately tied to and founded upon the economies of nature. It is more than a metaphor to state that amphibians and reptiles are employed and working for free. They really are doing work. So when politicians speak of job creation, they are not thinking about employment in the commonwealth. They are often presenting a one-sided perspective on job creation, the human perspective. This creates a dysfunction with the economy of the planet. The economy of nature that keeps us humans alive and living well is subsidized by the physical activities of organisms in ecosystems. This means that migration, bioturbation, and even decomposition must be protected and managed economically, because these processes alters the geo-physical states of the environments we live in.
I have a two professional designations. I'm a registered professional biologist (R.P. Bio.) with the BC College of Applied Biology and I am also a Certified Professional in Erosion and Sediment Control. The second designation is importantly tied to my expertise in herpetology. Western Toads in BC, for example, have been described as ecosystem engineers due to their large role in regulating the distribution of sediments in ponds and streams (Wood and Richardson, 2010). These amphibians are providing regulatory services in sedimentation. It is an interesting comparison, because I have been paid to design and implement plans on construction sites for erosion and sediment control. Western Toads are unrecognized professionals in this field.
When properly funded and supported, ecologists launch investigations to measure and identify rates and amounts of exchange of energy and materials through organisms and the varied environments they inhabit. They create the spreadsheets that give us estimations into the economic contributions of nature. Theories about trophic dynamics were developed in the turn of the 20th century advanced the science in this unrecognized branch of economics. It might seem odd to be making an economic argument for amphibians, but any theory of economics is plainly unscientific if we do not value the reality of power, energy, health services, and artistry within nature. Modern ecologists have expanded early concepts in ecology (e.g., food-webs) to help us map out and recognize the importance of the physical work and modifications to the environment.
These engineered webs have big effects on nutrient and energy dynamics in ecosystems. Niche construction theory has expanded the role of ecosystem engineering processes to address questions concerning evolutionary biology and how the cumulative effects of organism and their actions on the constructed environment alters fitness and selection across generations (Albuquerque et al., 2019).
These ecological theories relate importantly to the topic of ecosystem goods and services. They give us the tools we need to measure and relate their value and importance. Discussing the value and importance of ecosystems is an important part of messaging that is included in my public outreach campaigns.
In those areas where human land use pressure is greatest, amphibian habitat may supply a useful template with which to manage growth and ensure the provision of some ecosystem services. - Baldwin, Powell and Kellert (2011, p. 324)
A burning question of mine is how amphibians and reptiles relate to the natural resource economy. It is through the lens of ecological science that we can clearly confirm that amphibians and reptiles have a huge role in the forestry sector. While they are often left out of economic debates, amphibians definitely play a vital role in sustainable forest management. They also have roles in agriculture and health care through direct control and regulation of soil invertebrates and disease vectors, like mosquitoes. Amphibians are also a source of inspiration in art, children love them, and some of their skin compounds are proving effective in the biomedical field (Deng et al., 2019; Larsen, 2016).
It is important that we keep amphibians and reptiles employed in the forests, in agricultural landscapes, and in our urban centers, given that indirectly and directly improve the health and well-being of our society.
We know very little about the status of populations in the north. What kind of impact are the practices being promoted through legislation and training of young professional foresters having on amphibians? It is well-known that forestry has negative impacts on amphibians (Haggerty, Crisman, & Rohr, 2019). There is no current effort to systematically look into the effects of wide-scale harvesting practices on amphibians in the Boreal forests of BC. Amphibian and reptile populations are spread across the landscape, but the effect of harvesting and inserting new roads through their migratory corridors is not being considered in any serious way through current forest practices, laws, and regulations. I am working to model the effects of forestry on amphibian populations, but it no easy challenge to find the funding and resources needed to work on these creatures where their value is greatly underappreciated. In a future blog, I hope to be reporting on the outcomes of my research into this area that is being actively pursued while I continue to collect data in the field.
Is climate change having an impact? There are already climate change effects on the hydrologic variability and extremes in BC (Déry, Hernández-Henríquez, Owens, Parkes, & Petticrew, 2012). Amphibians are showing signs of climate sensitivity (i.e., declines) in response to changes in water availability (Miller et al., 2018). Temperature and snowpack during the coldest week of winter is related to survivorship rates (Muths et al. 2020) and significant trends of fewer winter snow-dominated durations, with important implications on hydrological and ecological processes (see Allchin and Déry 2017), are projected to negatively impact Western Toad survival. How are these impacts affecting the functions, goods, and services provided by amphibians to human society? This is an area of interest of mine and I have been encouraging student projects to advance research into these types of questions through my affiliation as an adjunct professor in the ecosystem science and management program at UNBC .
One of the most critical reasons for managing amphibians may be found in their role in the regulation of global carbon budgets. Amphibians are a vital part of the global strategy to address climate change. Unfortunately, this is a double-edged sword. Climate change is one of the causal factors implicated in global amphibian declines. Amphibians under stress migrate less and climate change is also altering the nutrient mediated pathways where warming has the potential effect of changing the nutrient concentrations in adults (Norlin, Byström, Karlsson, Johansson, & Liess, 2016).
Ecosystem services contribute more than twice as much to human well-being as global GDP. - Costanza et al. (2014)
Even though the dollar figure for amphibians and the services they provide is likely a significant indicator of our provincial economic wealth, it may take more than calculating and presenting a dollar figure to persuade economists, politicians, and businesses to adjust their budgets and practices. We communicate on the worth of things through budgets. It is culturally how we frame our way of thinking about the world around us.
There is no Department of Amphibians and Reptiles, but we harvest them nonetheless. It is called incidental take as forestry companies extract timber while tracking over habitats occupied and amphibians killed under the tracks of machines. This reduces the amount of ecological work that their populations are able to provide and it puts their future at risk. A lack of understanding into the value and importance of amphibians feeds into a cycle of reduced funding for the conservation and management of amphibians and reptiles. This is a costly mistake. We are loosing the great services that amphibians and reptiles provide to human civilization, our well-being, and the built-in resilience of our planet.
REFERENCES
Albuquerque, U. P., do Nascimento, A. L. B., da Silva Chaves, L., Feitosa, I. S., de Moura, J. M. B., Gonçalves, P. H. S., … Ferreira, W. S. (2019). A brief introduction to niche construction theory for ecologists and conservationists. Biological Conservation, 237, 50–56. https://doi.org/10.1016/j.biocon.2019.06.018
Allchin, M. I. & Déry, S. J. (2017). A spatio-temporal analysis of trends in Northern Hemisphere snow dominated area and duration, 1971–2014. Annals of Glaciology, 58, 21-35.
Baldwin, R. F., Powell, R. B., & Kellert, S. R. (2011). Habitat as Architecture: Integrating Conservation Planning and Human Health. Ambio, 40(3), 322–327. doi:10.1007/s13280-010-0103-7
Burton, T. M., & Likens, G. E. (1975). Energy Flow and Nutrient Cycling in Salamander Populations in the Hubbard Brook Experimental Forest, New Hampshire. Ecology, 56(5), 1068-1080. https://doi.org/10.2307/1936147
Capps, K. A., Berven, K. A., & Tiegs, S. D. (2015). Modelling nutrient transport and transformation by pool-breeding amphibians in forested landscapes using a 21-year dataset. Freshwater Biology, 60(3), 500–511. https://doi.org/10.1111/fwb.12470
Collins, J. P. & Crump, M. L. (2009). Extinction in our Times: Global Amphibian Decline. Oxford University Press. Pp. 304. https://global.oup.com/academic/product/extinction-in-our-times-9780195316940?cc=us&lang=en&
Costanza, R., d’Arge, R., Groot, R. de, Farber, S., Grasso, M., Hannon, B., … Belt, M. van den. (1997). The value of the world’s ecosystem services and natural capital. Nature, 387(6630), 253–260. https://doi.org/10.1038/387253a0
Costanza, R., de Groot, R., Sutton, P., van der Ploeg, S., Anderson, S. J., Kubiszewski, I., … Turner, R. K. (2014). Changes in the global value of ecosystem services. Global Environmental Change, 26, 152–158. https://doi.org/10.1016/j.gloenvcha.2014.04.002
Davic, R. D., & Welsh, H. H. (2004). On the Ecological Roles of Salamanders. Annual Review of Ecology, Evolution, and Systematics, 35(1), 405–434. https://doi.org/10.1146/annurev.ecolsys.35.112202.130116
Daniel J. Hocking and Kimberly J. Babbitt. (2014) Amphibian Contributions to Ecosystem Services. Herpetological Conservation and Biology 9(1):1−17. http://www.herpconbio.org/Volume_9/Issue_1/Hocking_Babbitt_2014.pdf
de Groot, R., Brander, L., van der Ploeg, S., Costanza, R., Bernard, F., Braat, L., … van Beukering, P. (2012). Global estimates of the value of ecosystems and their services in monetary units. Ecosystem Services, 1(1), 50–61. https://doi.org/10.1016/j.ecoser.2012.07.005
Deng, J., Tang, Y., Zhang, Q., Wang, C., Liao, M., Ji, P., … Tan, H. (2019). A Bioinspired Medical Adhesive Derived from Skin Secretion of Andrias davidianus for Wound Healing. Advanced Functional Materials, 29(31), 1809110. https://doi.org/10.1002/adfm.201809110
DuRant, S. E., & Hopkins, W. A. (2008). Amphibian predation on larval mosquitoes. Canadian Journal of Zoology, 86(10), 1159–1164. https://doi.org/10.1139/Z08-097
Fritz, K. A., & Whiles, M. R. (2018). Amphibian-mediated nutrient fluxes across aquatic–terrestrial boundaries of temporary wetlands. Freshwater Biology, 63(10), 1250–1259. https://doi.org/10.1111/fwb.13130
Haggerty, C. J. E., Crisman, T. L., & Rohr, J. R. (2019). Effects of forestry-driven changes to groundcover and soil moisture on amphibian desiccation, dispersal, and survival. Ecological Applications, 29(3), e01870. https://doi.org/10.1002/eap.1870
Jones, C. G., Lawton, J. H., & Shachak, M. (1994). Organisms as Ecosystem Engineers. Oikos, 69(3), 373–386. https://doi.org/10.2307/3545850
Larsen, G. D. (2016). Amputated amphibians advance regenerative medicine. Lab Animal, 45(3), 85. https://doi.org/10.1038/laban.964
Meredith, H. M. R., Van Buren, C. & Antwis R.E. (2016) Making amphibian conservation more effective. Conservation Evidence, 13, 1-5. https://www.conservationevidence.com/individual-study/5558
Miller, D. A. W., Grant, E. H. C., Muths, E., Amburgey, S. M., Adams, M. J., Joseph, M. B., … Sigafus, B. H. (2018). Quantifying climate sensitivity and climate-driven change in North American amphibian communities. Nature Communications, 9(1), 1–15. https://doi.org/10.1038/s41467-018-06157-6
Muths, E., L. L. Bailey, B.A. Lambert, and S. C. Schneider. (2018). Estimating the probability of movement and partitioning seasonal survival in an amphibian metapopulation. Ecosphere, 9(10), e02480. https://doi.org/10.1002/ecs2.2480
Naz, S., Akbar, H., Habib, S. S., Faiq, M., Rais, M., Malik, M. A., & Shafiq, A. Role of anuran tadpoles as biological control for dengue larvae. International Journal of Mosquito Research 2019; 6(3): 22-2. http://www.dipterajournal.com/pdf/2019/vol6issue3/PartA/6-2-11-198.pdf
Norlin, L., Byström, P., Karlsson, J., Johansson, M., & Liess, A. (2016). Climate change will alter amphibian-mediated nutrient pathways: Evidence from Rana temporaria tadpoles in experimental ponds. Freshwater Biology, 61(4), 472–485. https://doi.org/10.1111/fwb.12720
Rubbo, M. J., Lanterman, J. L., Falco, R. C., & Daniels, T. J. (2011). The influence of amphibians on mosquitoes in seasonal pools: Can wetlands protection help to minimize disease risk? Wetlands, 31(4), 799–804. https://doi.org/10.1007/s13157-011-0198-z
Semlitsch, R. D., O’Donnell, K. M., & Thompson, F. R. (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. https://doi.org/10.1139/cjz-2014-0141
Valencia-Aguilar, A., Cortés-Gómez, A. M., & Ruiz-Agudelo, C. A. (2013). Ecosystem services provided by amphibians and reptiles in Neotropical ecosystems. International Journal of Biodiversity Science, Ecosystem Services & Management, 9(3), 257–272. https://doi.org/10.1080/21513732.2013.821168
West, Josh. (2018). Importance of Amphibians: A Synthesis of Their Environmental Functions, Benefits to Humans, and Need for Conservation. In BSU Honors Program Theses and Projects. Item 261. Available at: http://vc.bridgew.edu/honors_proj/261
Wood, S. L. R., & Richardson, J. S. (2010). Evidence for ecosystem engineering in a lentic habitat by tadpoles of the western toad. Aquatic Sciences, 72(4), 499–508. https://doi.org/10.1007/s00027-010-0151-x
updated September 9, 2021
Comentários