Mazama Newt Conservation

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Welcome to Project Mazama Newt, where we discuss conservation of the Mazama newt.

Introduction[edit]

Anatomical variation between the rough-skinned newt and its subspecies the Mazama newt

The Mazama newt (Taricha granulosa mazamae) is a subspecies of the rough-skinned newt and is endemic to Crater Lake. While the life history of the Mazama newt is incomplete, it is known that the newt colonized Crater Lake around 6,000 years ago.[1] The Mazama newt survives on a diet of snails, aquatic insect larva, and terrestrial insects. [2] The Mazama newt can produce a low toxicity level of tetrodotoxin, a potentially lethal neurotoxin. [3]

Habitat[edit]

Crater Lake[edit]

Crater Lake is located in Klamath County in the southern part of Oregon, approximately 100 miles east of the Pacific Ocean and 80 miles northeast of Medford, the closest well-known town. The caldera, in which the lake occupies, is the result of the violent eruption of Mt. Mazama that took place 7,700 years ago [4]. The Crater Lake caldera is considered to be a dormant volcanic site today, with the most recent eruption occurring between 6,600 and 4,800 years ago [5] [6], which resulted in the creation of Wizard Island in the lake. Mt. Mazama, now the foundation of Crater Lake, was a composite volcano comprised of mostly andesite and decite [7], that started forming about 400,000 years ago and at its peak used to stand approximately 12,000 feet tall [8]. Mt. Mazama itself is part of the High Cascades volcanic chain, which is made up of volcanoes that range from Washington to California.

Aerial photo Crater Lake in Southern Oregon

The Cascadian Mountain chain, and the vulcanism that comes with it, is a result of the subduction of the Juan de Fuca plate underneath the North American plate. This subduction generated the magma supply for each of this volcanoes from Mt. Lassen in California to Mt. Baker in Washington, including Mt. Mazama. Vulcanism and mountain chain creation is a by-product of subduction is because once the subducting plate reaches 100 km the subducting plate starts to melt into magma, and the magma then rises to the surface of the other plate and creates volcanoes. Because it is a former volcanic giant, the lakes altitude is 8,159 feet [9].

The weather at Crater Lake is typical of a high altitude. During the winter months this area experiences significant snowfall with average temperatures ranging from 40*F to 18*F. During the summer months snowfall still occurs but is scarce and temperatures range from 70*F to 35*F depending on the time of day. The average annual lake temperature of Crater Lake is between 59*F and 38*F[10].

Mazama newt habitat[edit]

Mazama newts colonized the shorelines of Crater Lake around 6,000 years ago when the lake was still relatively young [11] and active volcanically. The shoreline of the lake, the primary habitat of the Mazama newt, primarily consists of cobble and boulder-sized rocks weathered and deposited from the cliffs above the shore with alternating bands of bedrock [12]. As adults these newts live mostly on the shoreline, returning to the water to lay their eggs. Larvae and juveniles newts live solely in the waters of Crater Lake. Mazama newts have a longer relationship with water throughout their lives as compared to other species of newts, which makes them more dependent on the conditions and ecology of the water where they spend so much time. When they are in the water, Mazama newts are benthic zone dwellers, meaning they live in the zone of water closest to the floor of the lake [13]. The benthic zone of Crater Lake is typical of that of a caldera; it has a minimal shoreline, steep walls, a fairly flat bottom with the exception of the two newer volcanic features (e.g., Wizard Island), and some volcanic debris [14].

Biological history[edit]

Crater Lake has an intricate, if small, food web. There are four species of blue-green algae, four species of green algae, and over 112 species of diatom algae [15]. There’s also the Drepanocladus moss, which forms massive colonies and can grow in waters up to 460 ft. deep, and the water buttercup, a flowering plant that grows on the surface of the water. The primary consumers are the water flea, the freshwater shrimp, snails, copepods, and bloodworms/midge larvae. The secondary consumers are dragonfly nymphs, tardigrades, and whirligig beetles. The tertiary consumers are the Mazama newts and signal crayfish, the latter being. At the top of the food-web are kokanee salmon and the rainbow trout. In 1888, officials began stocking the lake with seven different species of fish, only two of which survived to today[16].

Conservation status[edit]

Currently the endemic population of Mazama newts are facing the threat of a species commonly known as the signal crayfish, which was introduced to crater lake in 1915. Due to the fact that this species has dominated nearly 80% of the Crater Lake shoreline there has been massive reduction of Mazama newt abundance, leaving them to inhabit the few locations along the shoreline that the signal crayfish have not overrun [17]. Tests have been conducted indicating that the invasion of the crayfish not only reduced the abundance of the newt, but displace the newts from cover which render the newts even more vulnerable to other prey and alter their behavior [18]. Further expansion of the signal crayfish could lead to the eventual extinction of the unique Mazama species [19].

Signal crayfish[edit]

The signal crayfish was introduced to the Crater Lake ecosystem

The species of signal crayfish (Pacifastacus leniusculus ), was introduced to Crater lake in 1915 in an effort by state park officials to create a working food system for the introduced species of fish, including trout and salmon [20]. This system would attract visitors and generate revenue for the park, but had unintentional impacts on the endogenous population of Mazama newts, (Taricha granulosa mazamae). After its introduction in 1915, the signal crayfish has taken over the littoral zone of the lake (approximately 80% of the shoreline), which is also the habitat of Mazama newts, and they share many aspects of the same food web niche [21]. The signal crayfish is omnivorous, having a diet that consists of aquatic insects, detritus, and plant matter; this wide food range allows for the out-competition of endogenous species that have a narrower range of food sources [22]. The signal crayfish expansion and domination of the littoral zone of Crater Lake has caused the severe population decline of the Mazama newt; this is due to competition for food, energy expenditure to avoid aggression, and predation of the crayfish on newts [23].

Conservation strategies[edit]

Proposal 1: Captive breeding and release[edit]

Captive breeding and release programs have been known to be successful in the past. For example, researchers were able to help raise the population size of the Yellow-spotted mountain newts in Western Iran by using this conservation method. [24]

Captive breeding and release programs are done by first capturing sexually mature male and female newts for the purpose of breeding. Once the newts are breed and lay their eggs the adult newts are released back into their natural habitat. However, the eggs are kept and cared for in captivity until they reach their juvenile stage of their life; and then they are reintroduced into their natural habitat.

Proposal 2: Genomic modification[edit]

Directly modifying the genome is a potential option for eradicating the negative impacts of invasive species on ecosystems. Using the CRISPR/Cas9 system certain genes can be removed and replaced with more advantageous genes, that which reduce the impacts of invasive species in ecosystems. CRISPR/Cas9 is a system that takes altered genes, a Cas9 enzyme, and an RNA guide and inserts them into an organism. When said organisms mates, there is a 50% chance that the altered gene will be passed on. When the gene is passed on the Cas9 enzyme, led by the RNA guide cuts out the unwanted gene and then replaces it with the altered gene. The CRISPR/Cas9 is a much more complicated concept, however here it is very generally explained. Eventually the wild type gene will be dominated by the genetically altered gene, and therefore removing the unwanted threats [25].

A recent study on mosquitoes was conducted that had two approaches. One is to genetically alter them so that they are immune to diseases such as malaria and the Zika virus, and the second is to essentially create daughterless offspring thus removing mosquitoes from the equation all together [26]. This same concept could be applied to the signal crayfish in Crater Lake, Oregon. By making daughter-less offspring eventually the crayfish will be removed from the ecosystem and the newts will be able to return to normal abundance. This certainly leads to questions such as, do we want to completely remove crayfish from the ecosystem? What other impacts would the removal of the crayfish have on the ecosystem? This technology is a ways away from being perfected but many studies and tests are being conducted using this idea of gene driving, and the CRISPR/Cas9 technology.

Proposal 3: Biological control[edit]

To control the expansion and aquatic dominance of the signal crayfish over the Mazama newt a course of action could be to introduce a freshwater parasite called Psorospermium haekeli. This species was discovered in 1883 and affects species of crayfish. It resides in the thoracic cavity of the crayfish where it will parasitize the crayfish from its connective tissues and thoracic endothelial tissues that lead to the brain. By the introduction of this freshwater parasite that is specific to only the crayfish population of Crater Lake, we can hinder the relative fitness of the while not disrupting other endogenous aquatic species[27]. This method would be applicable to a cooperative approach with other methods due to it's very specific ecological effect and less than devastating effects. Caution would be advised with the consumption of crayfish with this parasite as studies have not concluded if it is safe for human consumption. Psorospermium haekeli is an amoeba that is speculated to posses many different morphologies, and if cyst morphology exists it could allow for the amoeba to survive in boiling or freezing temperatures, potentially risking consumer health if found to be pathological.

Proposal 4: Physical barriers[edit]

Currently, placing fencing to keep the crayfish from advancing further along the shoreline is being considered for containing the signal crayfish population in Crater Lake. Because signal crayfish don't swim high or burrow deep, all that would be needed is a foot and a half tall metal fence funning in a straight line from the shore into the water. There are several concerns about this. The main concern is that the fences would ruin the lake's aesthetic. Another concern is how far down the fences have to stretch because crayfish have been found at depths of up to 800 feet. Studies are currently being done on whether or not these deepwater residing crayfish return to the shallows[28]. In the Investigation of Crayfish Control Technology Report by the Arizona Fish and Game Department, physical barriers such as fencing were found to be at best temporary solutions, although they can make trapping easier.

Proposal 5: Trapping, predation, and augmentation[edit]

In order to preserve the Mazama newt and protect it from extinction, something has to be done about the increasing signal crayfish population, even if it’s only a temporary solution. Unfortunately once these crayfish are introduced to an ecosystem and allowed to take hold, they are almost impossible to remove or control. In fact, almost all conventional methods, trapping, manual catching, habitat barriers, controlled diseases, increased predation, etc. by themselves have been widely unsuccessful in removing or even managing invasive crayfish populations [29]. North American crayfish are resilient, rapid reproducers, and eat almost anything, from insects, snails, and small fish, to others of their species if necessary [30]. They can even remain fully functioning, albeit sterile, after being exposed to 40 Gy of radiation (four times the letal dose to a human) [31].

In other invasive populations, such as the European green crab (Carcinus maenas) in British Columbia, the method of annual trapping has been shown to be an effective temporary solution to the population size. However due to other factors, immigration of more crabs, a surviving larval population, and a lack of trapping frequency, trapping alone hasn’t been enough to suppress the population to the desired levels for a large amount of time (i.e. longer than a year) [32]. Luckily, Crater Lake is an enclosed ecosystem, so there are no crayfish immigrating to the area; which only leaves the challenge of how to remove or lessen the already existing signal crayfish population from the lake. There is evidence that intensive trapping along with increased fish predation of crayfish populations can drastically reduce crayfish population size [33] and at this time, these measures seem to be the best option for decreasing the crayfish population of Crater Lake. However, though they seem to solve the immediate threat that the crayfish pose to the Mazama newt, these measures also take time and effort, and do not completely remove the crayfish from the area, meaning they would continue to be a threat in the future if not carefully controlled.

Right now the Mazama newt population is very low, with fewer than 12 newts found at any single testing site in the lake (compared to the crayfish found in the hundreds per site) [34]. In other populations, such as North American freshwater mussels (Mollusca: Bivalvia: Unionoida), controlled propagation, augmentation, and reintroduction of the species has worked to boost population size in dire circumstances [35]. In the case of the Mazama newt, controlled propagation, augmentation and reintroduction would be to their benefit in conjunction with heavy trapping and fish predation of the signal crayfish. This step would help return the Mazama newt population to reasonable numbers along with keeping a balance with the available food supply of the lake as to not exceed its capabilities to support the population.

In conclusion, unless we are able to completely remove the signal crayfish population from the lake or create a balance to keep their numbers in check, we will constantly be involved in manually managing the newt and crayfish population numbers. However, if nothing is done, if no steps are taken to ensure the survival of the Mazama newt, it will become extinct while we are all watching.

References[edit]

  1. National Park Service, "Mazama Newt Toxicity", 2018
  2. Farner, Donald S., Kezer J., "Notes on the Amphibians and Reptiles of Crater Lack National Park." The American Midland Naturalist, Vol.50, no.2, 1953
  3. National Park Service, "Mazama Newt Toxicity", 2018
  4. Orr, Elizabeth and William Orr. Oregon Geology. 6th ed., Oregon State University Press, 2014, p. 164.
  5. “Crater Lake - Home.” U.S.G.S., www.usgs.gov/volcanoes/crater-lake/. Accessed 11 June 2020.
  6. Orr, Elizabeth and William Orr. Oregon Geology. 6th ed., Oregon State University Press, 2014, p. 160.
  7. “Crater Lake - Home.” U.S.G.S. www.usgs.gov/volcanoes/crater-lake/. Accessed 11 June 2020.
  8. Orr, William and Elizabeth Orr. Geology of the Pacific Northwest. 2nd ed., Waveland Press, Inc., 2002, p.94.
  9. “Crater Lake - Home.” U.S.G.S., www.usgs.gov/volcanoes/crater-lake/. Accessed 11 June 2020.
  10. “Weather.” N.P.S., 29 Mar. 2020, www.nps.gov/crla/planyourvisit/weather.htm. Accessed 11 June 2020.
  11. “Mazama Newt Distributions.” N.P.S., 28 Feb. 2015, www.nps.gov/crla/learn/nature/newtdistribution.htm. Accessed 12 June 2020.
  12. Girdner, S.F., Ray, A.M., Buktenica, M.W. et al. “Replacement of a unique population of newts (Taricha granulosa mazamae) by introduced signal crayfish (Pacifastacus leniusculus) in Crater Lake, Oregon.” Biol Invasions 20, 721–740 (2018). doi.10.1007/s10530-017-1570-6. Accessed 12 June 2020.
  13. Girdner, S.F., Ray, A.M., Buktenica, M.W. et al. “Replacement of a unique population of newts (Taricha granulosa mazamae) by introduced signal crayfish (Pacifastacus leniusculus) in Crater Lake, Oregon.” Biol Invasions 20, 721–740 (2018). doi.10.1007/s10530-017-1570-6. Accessed 12 June 2020.
  14. Marshak, Steve. Earth Portrait of a Planet. 5th ed., W.W. Norton & Company, Inc., 2015, p.283.
  15. Bacastow, Wesley
  16. “Fishing” Crater Lake National Park Service
  17. Buktenica, M. W., et al. “The Impact of Introduced Crayfish on a Unique Population of Salamander in Crater Lake, Oregon (U.S. National Park Service).” National Parks Service, U.S. Department of the Interior, 4 Sept. 2015, www.nps.gov/articles/parkscience32_1_5-12_buktenica_et_al_3815.htm
  18. Buktenica, M. W., et al. “The Impact of Introduced Crayfish on a Unique Population of Salamander in Crater Lake, Oregon (U.S. National Park Service).” National Parks Service, U.S. Department of the Interior, 4 Sept. 2015, www.nps.gov/articles/parkscience32_1_5-12_buktenica_et_al_3815.htm
  19. Buktenica, M. W., et al. “The Impact of Introduced Crayfish on a Unique Population of Salamander in Crater Lake, Oregon (U.S. National Park Service).” National Parks Service, U.S. Department of the Interior, 4 Sept. 2015, www.nps.gov/articles/parkscience32_1_5-12_buktenica_et_al_3815.htm
  20. Umek, John., Dr. Sundeep, Chandra. The ecology of signal crayfish in two large ultra-oligotrophic ecosystems: Crater Lake and Lake Tahoe. Dissertation. University of Nevada, Reno. 2016.
  21. Buktenica, Mark & Girdner, Scott & Ray, Andrew & Hering, David & Umek, John. The impact of introduced crayfish on a unique population of salamander in Crater Lake, Oregon. Park Science. 32. 5-12. (2015).
  22. Hogger JB. Ecology, population biology, and behaviour. In: Holdich DM, Lowery RS, eds. Freshwater Crayfish. Biology, Management and Exploitation. London, Portland: Croom Helm Ltd., 114-144, 424-479 (1988).
  23. Buktenica, Mark & Girdner, Scott & Ray, Andrew & Hering, David & Umek, John. The impact of introduced crayfish on a unique population of salamander in Crater Lake, Oregon. Park Science. 32. 5-12. (2015)
  24. Mozafar S. Somaya V., Endangered Species Research, "Captive breeding and trial reintroduction of the endangered yellow-spotted mountain newt neurergus microspilotus in western Iran", Vol. 23, 2014
  25. “Gene Drives.” Wyss Institute, Harvard University , 27 Sept. 2019, https://wyss.harvard.edu/technology/gene-drives/
  26. Keele, Jacque. "Using Genetic Manipulation to Control invasive Species. Sept. 2017. https://www.usbr.gov/research/projects/download_product.cfm?id=2670
  27. Vogt, G, and M Rug. “Microscopic Anatomy and Histochemistry of the Crayfish Parasite Psorospermium Haeckeli.” Diseases of Aquatic Organisms, vol. 21, 1995, pp. 79–90., doi:10.3354/dao021079.
  28. Burns, Jess "Perfect Invaders: How Crayfish Are Threatening Crater Lake's Smallest Creatures"
  29. Hyatt, Matthew W., “Investigation of Crayfish Control Technology.” Arizona Fish and Wildlife, www.usbr.gov/lc/phoenix/biology/azfish/pdf/CrayfishFinal.pdf. Accessed 12 June 2020.
  30. Kelly, Daniel. “Struggling Crater Lake Mazama Newts.” Lake Scientist, 8 Dec. 2015, www.lakescientist.com/struggling-crater-lake-mazama-newts/. Accessed 12 June 2020.
  31. Manfrin, Chiara, et al. “Detection and Control of Invasive Freshwater Crayfish: From Traditional to Innovative Methods.” Diversity, 4 January 2019, www.mdpi.com/1424-2818/11/1/5/pdf Accessed 12 June 2020.
  32. Duncombe, Lynda G. and Thomas W. Therriault. “Evaluating trapping as a method to control the European green crab, Carcinus maenas, population at Pipestem Inlet, British Columbia.” REABIC, 14 Feb. 2017, https://www.reabic.net/journals/mbi/2017/2/MBI_2017_Duncombe_Therriault.pdf). Accessed 12 June 2020.
  33. Hein, Catherine, et al. “Intensive trapping and increased fish predation cause massive population decline of an invasive crayfish.” Research Gate, May 2007, www.researchgate.net/publication/262945675_Intensive_trapping_and_increased_fish_predation_cause_massive_population_decline_of_an_invasive_crayfish. Accessed 12 June 2020.
  34. “Mazama Newt Distributions.” N.P.S., 28 Feb. 2015, www.nps.gov/crla/learn/nature/newtdistribution.htm. Accessed 12 June 2020.
  35. Stephen E. McMurray and Kevin J. Roe. "Perspectives on the Controlled Propagation, Augmentation, and Reintroduction of Freshwater Mussels (Mollusca: Bivalvia: Unionoida)," Freshwater Mollusk Biology and Conservation, 20(1), 1-12, 1 Mar. 2017, bioone.org/journals/freshwater-mollusk-biology-and-conservation/volume-20/issue-1/fmbc.v20i1.2017.1-12/Perspectives-on-the-Controlled-Propagation-Augmentation-and-Reintroduction-of-Freshwater/10.31931/fmbc.v20i1.2017.1-12.full Accessed 12 June 2020.