The members of the Springsnails (genus Pyrgulopsis) account for a substantial amount of the diversity of western North American aquatic biota. As utilization of water habits increases, the threats to the diversity of Springtails has dramatically risen. Prior, the neglect of biodiversity has caused considerable impacts to Springsnail populations. Growing concerns have caused a growing conservation force with several species being listed under the Endangered Species Act, and ecosystem rehabilitation. Despite this, numerous anthropogenic threats still pose problems, namely habitat fragmentation and invasive molluscs.
These are worrisome in consideration of the evolutionary history of Springsnails. The evolutionary history of Springsnails impacts the population’s reaction to these novel threats. The derived traits which are of note include range, population, habitat and correlating adaptations. Conservation measures, such as naturalizing habitats, require these traits to be considered. Recent molecular studies have given more tools to understand the phylogeography, life history, and genetics of snail populations, such as P. bruneaunsi. Furthermore, the prior studies have highlighted the roles Pyrgulopsis play within the ecosystem that are vital to the overall health of the environment.
Despite this, there is a lack of major conversation surrounding Springsnail conservation. This presentation is an attempt to demonstrate the importance of Springsnails evolutionary history when considering conservation measures.
Springsnails, or Pyrgulopsis is a western American hydrobiid gastropod. Pyrgulopsis is one of the most species rich genus of fresh-water molluscs in the Americas, with 126 to 133 recognized species. These typically tiny, water breathing molluscs are distributed throughout the West. Typically, they can be found in small, spring fed environments, contributing to their common name.
Within the Great Basin, Springsnails are typically found in perennial wetlands.
Pyrgulopsis diversity can be seen throughout the Great Basin region. The springsnail being one of the most diverse species in aquatic ecosystems shows its importance in these small stream areas.
-Insert more about diversity, include SSA finding and some implication
-Why would diversity increase their importance
-Find more sources on diversity in Great Basin wetlands
The lack of literature about Great Basin springsnails
-Explain the gap to an extent
-Why this makes their conservation more significant to the scientific community
The importance of the evolutionary history of Springsnails lies in their management implications. By understanding the mechanisms behind the evolution of Springsnails, their ecological role, behavior and development become more clear. Because of this, a proper outline of their history is important to make proper management decisions.
The evolutionary history of springsnails prior to the 2000s was widely unknown. This was due to a couple of key facts. Foremost, the anatomy of Gastopoda are not typically well suited for fossilization; their soft bodies hardly ever fossilize, leaving just their hard shells. This is a particular issue with Pyrgulopsis associated anatomy. The shell typical of Springsnails is relatively hard to fossilize due to being thin and minute. Secondly, the taxonomy of Mollusca is widely understudied considering their relative abundance; there have been several major revisions and additions to the taxonomy in recent years Because of the above reasonings, molecular studies have been key to the understanding of the evolutionary history of Springtails.
Since the development of more complex molecular studies, Springsnail evolutionary history has become more apparent. The origins of Pyrgulopsis arise from a series of Neogenic drainage transfers involving the Missouri River Basin. A speculated Neogene drainage basin near the Missouri River Basin is the purpose origin for the genus. During this time, a series of geologic events caused stream capture events, which is thought to have caused the Neogene drainage basin to flow across the northern continental divide. In turn, drainage basin which was thought to flow southward from Missouri river to Idaho then further south. As a result, the headwater of this late Neogene drainage poured over southeastern Nevada into what is now the Great Basin. This hypothesis is corroborated with molluscan as well as geographic studies.
Furthermore, the recent migration of Pyrgulopsis into Eastern Great Basin across the Wasatch divide further supports the headwater transfer hypothesis. The phylogeographic structure of Pyrgulopsis kolobenisis across the Wasatch divide shows similarities. The genetic similarity between the two geographically isolated populations implies recent displacement.
In terms of Springsnail conservation, the phylogeography of a given species is of particular note.
Importance of Springsnails:
Springsnails are a species that is often missed when looking at a stream and small water ecosystems. The species of focus in the great basin is the Pyrgulopsis bruneaunsi which is located in mainly stream, pond and spring ecosystems. The springsnail plays a vital role in keeping these stream type ecosystems healthy and would be considered an indicator species for this ecosystem. These springsnails have a vast importance, “in suitable habitats throughout much of western North America, which suggests a possibly important role in ecosystem function (e.g., as primary consumers); they are also useful indicators of perennial water sources” (Hershler, 2014). These snails are not only important indicator species, but play a role of primary consumer in this ecosystem. As a primary consumer these springsnails, “help make life possible for countless other species sharing their desert-oasis homes, converting algae, microorganisms and decaying matter into edibles for other invertebrates, fish, birds, turtles, amphibians and small mammals” (Curry, 2012). This important function of the springsnails could classify them as a keystone species and solidifies the indicator species label. The springsnails by converting algae and decaying matter into edibles helps with the spring water quality. These springsnails allow for nutrient recycling and shape water chemistry. These species are vastly important and are the controller of the food chain and “Without them, food chains would unravel and wetland living conditions could fall fatally out of whack” (Curry, 2012). The food chain support that these springsnails provide are definitely an important role to all of the other species that inhabit these great basin small water ecosystems. The springsnails play an important role, but are an understudied species and with many new species being discovered all the time, “The hydrobiid gastropod genus Pyrgulopsis (133 species) is one of the most diverse elements of the western North America aquatic biota” (Liu, 2012). This springsnails being so diverse shows that they must have a specialized, but very important role in the stream and spring ecosystems across the great basin.
There are certain threats to different species of springsnails. Most of these threats are human induced such as groundwater mining and livestock grazing. With the groundwater mining comes the threat of toxic chemicals such as copper leaking into spring systems. “Copper is acutely toxic to, and directly affects, primary producers and decomposers, which are key players in essential processes such as the nutrient cycle in freshwater ecosystems,” (Gardham 2015). The effects of copper were studied on phytoplankton, periphyton and other similar organisms in an outdoor facility. The study concluded that there are both direct and indirect effects from copper contamination in the water. Direct effects included decreased macrophyte growth and subsurface organic matter decomposition. “These latter responses were attributed to indirect effects, due to a reduction in grazing pressure from snails, particularly Physa Acuta, in the higher copper contaminated mesocosms,” (Gardham, 2015). What the study showed is that copper indirectly affected snail grazing pressures. Grazing pressures correlate with algal growth, so a change in grazing pressure could cause different characteristics to the ecosystems that the snails live in. Springsnails are known to have a narrow geographic distribution which makes them susceptible to extinction at a local level. “Owing to their strong groundwater dependency, and typically narrow geographic ranges, often consisting of a single spring or spring complex, springsnails are especially vulnerable to extirpation and extinction in the case of local endemics,” (Hershler 1998). With the changing climate, more springsnail species are going to become extinct. Studies show that between 10 and 20 thousand species have become extinct or imperiled from human interactions. Studies also show that freshwater species around the world have been on a decline since the 1970s. Springsnails have been subject to harm through groundwater pumping which dries up the spring that the springsnails are narrowly living in. The springsnails go extinct due to, “Groundwater pumping and depletion in western North America [which] is occurring rapidly” (Aeschbach-Hertig and Gleeson, 2012). This has caused the elimination of several springsnail species, including Pyrgulopsis brandi, which became extinct in the early 1970s, after the spring complex near Palomas, Chihuahua, (its single locality) dried as a consequence of groundwater pumping.
The large number of dried springs that are scattered throughout the West suggests the likelihood of additional, unrecorded springsnail extinctions.
The threat posed by aquifer drawdown is exacerbated in several parts of the West (which are underlain by well-integrated subsurface drainage networks), where local groundwater extraction potentially jeopardizes entire regional faunas
The common practice of capturing and diverting surface flows (e.g., for agricultural or pastoral uses) has also had a devastating impact on springsnail populations. For example a population of Pyrgulopsis longiglans became extirpated after spring flows were diverted to stock tanks. In cases in which a portion of the groundwater discharge continues to flow onto the landscape, springsnails may persist, albeit in a smaller habitat
Species invasions are known to have contributed to the decline of native mollusks in the United States. The negative effects of invasive mussels are well-known, but freshwater snails and spring environments have received much less attention. Considerable numbers of non-native species have been introduced into spring environments, both intentionally and inadvertently. At least fifty nonnative fish taxa and several invertebrate taxa have been introduced into aquatic communities in the Great Basin. Nonnative aquatic species were introduced to the Great Basin from other parts of North America and from Europe, Asia, Africa, and South America, and many of these introduced species are now widespread
The springsnail has been relatively unnoticed by the scientific community until recently, which has only been minor attention and little research completed. Since the early 1900s when increased study of the springsnail began at least five different species have gone extinct. With about 80% of the remaining species being placed on the endangered species list(Hershler, 2012). Increased conservation of wildlife in the west has led to increased monitoring of the species. In the past two decades there has also been an increasing amount of springsnail conservation activities in the Great Basin and the American Southwest. An extensive field survey of Great Basin springsnails in the 1990s resulted in the description of 58 new species and established a baseline for the conservation status. The Nature Conservancy and the Desert Research Institute recently assessed the current condition of a large number of the springsnail localities in Nevada, and follow-up actions are planned to reduce threats from livestock grazing and to restore impaired sites. Extensively modified springsnail habitats in the Ash Meadows Wildlife Refuge have been restored by the removal of impoundments, the rerouting of discharge into historical flow channels, and the eradication of introduced cichlids and crayfish. The U.S. Bureau of Reclamation’s recent spring management guide is the best example of a conservation effort to maintain springsnail habitats and populations. It covers numerous spring species and functions, and specifically discusses springsnail conservation. Aside from this effort, habitat protection in the form of riparian, spring, or stream system maintenance constitutes the primary range-wide conservation action in place to conserve populations of Pyrgulopsis. Numerous programs are in place from multiple state and federal agencies that protect and conserve riparian, spring, and stream systems on the lands for which they are responsible.