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Survival and behavior of Chinese mystery snails (Bellamya Chinensis) in response to simulated water body drawdowns and extended air exposure
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Nonnative invasive mollusks degrade aquatic ecosystems and induce economic losses worldwide. Extended air exposure through water body drawdown is one management action used for control. In North America, the Chinese mystery snail (Bellamya chinensis) is an invasive aquatic snail with an expanding range, but eradication methods for this species are not well documented. We assessed the ability of B. chinensis to survive different durations of air exposure, and observed behavioral responses prior to, during, and following desiccation events. Individual B. chinensis specimens survived air exposure in a laboratory setting for > 9 weeks, and survivorship was greater among adults than juveniles. Several B. chinensis specimens responded to desiccation by sealing their opercula and/or burrowing in mud substrate. Our results indicate that drawdowns alone may not be an effective means of eliminating B. chinensis. This study lays the groundwork for future management research that may determine the effectiveness of drawdowns when combined with factors such as extreme temperatures, predation, or molluscicides.
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... Although an aquatic mollusc, initial air exposure experiments found that adult snails can survive at least 4 weeks of air exposure and juvenile snails survive 3-14 days (Havel 2011). Other desiccation experiments suggest that adult C. chinensis can survive exposure for longer than 9 weeks (Unstad et al. 2013). Finally, the concentration of calcium required (Table 1) by C. chinensis, at < 2 ppm, is very low compared to other molluscs, such as the zebra mussel (Dreissena polymorpha), quagga mussel (Dreissena rostriformis bugensis), and other calcifying AISs such as banded mystery snail and rusty crayfish (Faxonius rusticus) (Chiu et al. 2002;Latzka et al. 2015). ...
... Commonly employed molluscicides, including rotenone and copper sulphate, are not effective in controlling or eliminating C. chinensis (Haak et al. 2014) and can be toxic to other invertebrates. Drawdowns, in which the water is removed from a specific water body, will likely not eradicate C. chinensis because the species can survive periods of desiccation exceeding 9 weeks (Unstad et al. 2013). Furthermore, long periods of air exposure, or increased predator pressure, has only been found to elevate C. chinensis reproductive rates (Prezant et al. 2006;Unstad et al. 2013; and personal observation of laboratory cultures). ...
... Drawdowns, in which the water is removed from a specific water body, will likely not eradicate C. chinensis because the species can survive periods of desiccation exceeding 9 weeks (Unstad et al. 2013). Furthermore, long periods of air exposure, or increased predator pressure, has only been found to elevate C. chinensis reproductive rates (Prezant et al. 2006;Unstad et al. 2013; and personal observation of laboratory cultures). Juvenile C. chinensis typically hide under rocks and burrow into sediment, so it is impractical to manually cull populations of C. chinensis (Jokinen 1982). ...
Evidence suggests that the Chinese mystery snail, Cipangopaludina chinensis, a freshwater, dioecious, snail of Asian origin has become invasive in North America, Belgium, and the Netherlands. Invasive species threaten indigenous biodiversity and have socioeconomic consequences where invasive. The aim of this review is to synthesize the relevant literature pertaining to C. chinensis in Canada. In doing so, we (i) describe C. chinensis ecosystem interactions in both indigenous (Asia) and non-indigenous habitats (North America and Europe), (ii) identify gaps in the literature, and (iii) determine where the species potential distribution in North America requires further exploration. We also briefly discuss potential management strategies for this species, as an aquatic invasive species (AIS), in Canada. Due to the much larger relative size of adult C. chinensis, multiple feeding mechanisms, and resistance to predation, C. chinensis can out-compete and displace indigenous freshwater gas-tropods and other molluscs. Furthermore, C. chinensis can affect food webs through bottom-up interactions with the bacterial and zooplankton communities by changing nitrogen and phosphorous concentrations. Also, the Chinese literature indicates the potential for C. chinensis to act as a biotransfer of contaminants between polluted ecosystems and consumers. In its indigenous range, C. chinensis was identified as a host for numerous parasites harmful to human and animal consumers alike. A comparison of the Canadian geographical distribution of reported occurrences with that for the United States indicates several potential gaps in Canadian reporting, which merits further investigation and consideration, especially in regard to federal and provincial non-indigenous monitoring and regulations. Southern Ontario had the highest number of reports that were mostly from web-based photo-supported sources. This suggests that interactive citizen science through popular apps backed by well-supported educational campaigns may be a highly effective means of tracking C. chinensis spread, which can be complementary to traditional methods using specimen-vouchered taxonomically verified natural-history collections overseen by professional curators. Résumé : Il semblerait que la vivipare orientale, Cipangopaludina chinensis, un escargot d'eau douce dioïque d'origine asiati-que, soit devenue envahissante en Amérique du Nord, en Belgique et aux Pays-Bas. Les espèces envahissantes menacent la biodiversité indigène et ont des conséquences socio-économiques aux endroits où elles sont envahissantes. L'objectif de cette étude est de faire une synthèse de la littérature pertinente relative à C. chinensis au Canada. Ce faisant, les auteurs (i) décrivent les interactions entre C. chinensis et de l'écosystème dans les habitats indigènes (Asie) et non indigènes (Amérique du Nord et Europe), (ii) identifient les lacunes de la littérature et (iii) déterminent les endroits où la répartition potentielle de l'espèce en Amérique du Nord nécessite une exploration plus approfondie. Ils abordent aussi brièvement les stratégies de gestion possibles pour cette espèce à titre d'espèce aquatique envahissante (EAE) au Canada. En raison de la taille relative beaucoup plus importante de C. chinensis adulte, de multiples mécanismes d'alimentation et de la résistance à la prédation, C. chinensis peut supplanter et déplacer les gastéropodes et les autres mollusques d'eau douce indigènes. En outre, C. chinensis peut affecter les réseaux alimen-taires par des interactions ascendantes avec les communautés bactériennes et zooplanctoniques en modifiant les concentrations d'azote et de phosphore. De plus, la littérature chinoise indique que C. chinensis peut agir comme agent de transfert biologique de contaminants entre les écosystèmes pollués et les consommateurs. Dans son aire de répartition indigène, C. chinensis a été identi-fié comme hôte pour de nombreux parasites dangereux pour les humains et les animaux qui les consomment. Une comparaison de la répartition géographique des signalements au Canada et aux Etats-Unis révèle plusieurs lacunes potentielles dans les signalements canadiens qui doivent être approfondies et prises en compte, notamment en ce qui concerne la surveillance et la réglementation fédérales et provinciales des espèces non indigènes. Le sud de l'Ontario a enregistré le plus grand nombre de signalements qui provenaient pour la plupart de sources photographiques sur Internet. Cela suggère que la science Environ. Rev. Downloaded from cdnsciencepub.com by 156.34.203.170 on 06/16/21 For personal use only. citoyenne interactive, par des applications populaires soutenues par des campagnes d'éducation bien étayées, peut être un moyen très efficace de suivre la propagation de C. chinensis, qui serait complémentaire aux méthodes traditionnelles supervisées par des conservateurs professionnels qui utilisent des collections de spécimens témoins vérifiés sur les plans de l'histoire naturelle et de la taxonomie. [Traduit par la Rédaction]
... Inverse stratifi cation in the winter precludes the event of benthic temperatures reaching less than 0 °C in most temperate lakes (Wetzel 2001). Additionally, B. chinensis has been observed to burrow under adverse conditions (Unstad et al. 2013), perhaps isolating the animal from extreme temperatures. Based on the current evidence and current climatic conditions of the United States and Canada, we suggest that B. chinensis will not be limited geospatially on the basis of current climatic patterns alone. ...
... Although desiccation is a primary source of mortality in animals during drawdowns, it is an improbable method for inducing Bellamya chinensis mass mortality. Bellamya chinensis are capable of closing their operculum extended periods both in and out of water, supporting the ability to withstand dry and hot conditions for at least 8 weeks (Havel 2011, Unstad et al. 2013). Additionally, this study identifi ed an in-water, upper temperature limit of approximately 45 °C. ...
The Chinese mystery snail, Bellamya chinensis (Gray, 1834) is a gastropod native to East Asia and is considered an invasive species in North America where its impacts on native species and ecosystems are not well understood. Scientific literature describing its biology and life history are sparse. Thermal tolerance limits, or the maximum and minimum temperature under which a species can survive, are key to identifying the potential geographical range of a species. The ability of managers to control invasive species is directly impacted by the thermal tolerance limits of a species. We attempted to identify the thermal tolerance limits of B. chinensis in a laboratory setting. Using a random sampling design, we exposed groups of wild-caught B. chinensis to either extreme high or low temperature treatments. We identified the upper temperature tolerance limit as between 40 and 45 °C. This result indicates some hot water management techniques may successfully prevent spread of B. chinensis among waterways. Despite exposing B. chinensis to freezing temperatures for extended periods of time we did not identify a lower temperature limit. Identifying the thermal tolerance limits of this and other invasive species informs predictions of range expansion and identification of potential prevention efforts.
... In cases where non-native snails have strong negative effects on species of conservation concern or on economic interests, the feasibility of snail elimination may be relatively low. Possible strategies include biocontrol, chemical treatments, drying of waterbodies, or manual removal of snails (Carmosini et al., 2018;Halwart, 1994;Horgan, Felix, et al., 2014;Joshi, 2007;Olivier et al., 2016;Unstad et al., 2013). Of these, biocontrol has been utilized in a handful of cases. ...
• Non-native freshwater snails can play important roles as consumers, hosts, and prey. Despite their potential ecological importance, global patterns in non-native snail taxonomy, geography, and ecology have not been documented. Our objectives were to use a semi-quantitative systematic review to describe non-native freshwater snail global diversity, distribution, mechanisms of introduction, and interactions with natural enemies, including parasites and predators.
• Based on 506 relevant publications, we recorded 95 non-native freshwater snail species from 16 families. Six taxonomic families, and pulmonate snails as a group, were over-represented relative to the number of species expected by chance. Eight snail species represented 63% of the research records. A few snail taxa (15%) were widespread global invaders, reported from four or more continents, while most invasions were limited to a single continent. Australia and the Pacific Islands were the largest ‘sink’ for non-native snails, with the greatest difference in the number of non-native taxa relative to native taxa that had spread to other continents.
• Aquarium hobby sales were implicated as the most common mechanism of introduction (41% of species), followed by “hitchhiking” on aquatic vegetation, human consumption, use for biocontrol, transportation in canals, commercial shipping, and outdoor recreation. A search of internet sales posts indicated that four of the six over-represented snail families were readily available for purchase online.
• Non-native snails hosted parasites of wildlife, livestock, and human health importance, yet on average had 80% lower parasite richness in their non-native compared to native range. At least 65 taxa were documented as consumers of non-native snails, including native predators of conservation concern. These findings suggest that non-native snails often are released from parasitism, but may commonly experience biotic resistance from predators.
• Our synthesis emphasizes the relatively high diversity of non-native snails, but the disproportionate role of a few taxonomic groups in driving ecological, economic, and public health challenges. Moving forward, it will be important to limit new snail introductions through policy, education, and monitoring, particularly as the effective control of established snail invasions remains challenging in most ecosystems.
... The ability of snails to bury into the ground, cover their shell mouth with operculum, and persist throughout unfavorable periods in moistened soils allows them to survive. Viviparidae are able to survive for several weeks without water [19,20]. The studied areas of the Novosibirsk reservoir remain dry for 2-3 months, which leads to the death of snails. ...
Mollusks are the macroinvertebrates most commonly introduced into fresh water. In invaded reservoirs, alien mollusks form a large biomass due to their large size. Climate change, water level regulation, and anthropogenic impacts on the environment lead to the drying up of water bodies and the death of littoral macroinvertebrates. To assess the impact of invasive snail mass mortality on water quality, laboratory experiments on the snail tissue decomposition were performed, the potential release of nutrients into aquatic ecosystems was calculated, and the predicted concentrations of nutrients were verified by field studies. The laboratory experiment showed quick decomposition of the common river snail Viviparus viviparus tissues with release into the environment of ammonium and total phosphorus of 2.72 ± 0.14 mg and 0.10 ± 0.02 mg, respectively, per gram of decomposing tissue. The concentrations of ammonium, nitrates, and total phosphorus at the site of snail death reached 2.70 ± 0.10, 3.13 ± 0.38 and 0.30 ± 0.02 mg/L, respectively. This indicates local contamination of the Novosibirsk reservoir littoral with decomposition products. The aquatic management, water level regulation, and control of undesirable species should take into account the likelihood of water quality decreasing as a result of macroinvertebrate mass mortality.
... Female C. chinensis produce large broods of live young. Estimates of > 100 offspring / female/ year have been suggested (Haak 2015;Havel 2011;Stephen et al. 2013;Unstad et al. 2013). Being more resistant to predation than native molluscs due to large size and the presence of a protective operculum "trapdoor" (Haak 2015;Johnson et al. 2009;Karatayev et al. 2009;Olden et al. 2013;Plinski et al. 1978;Sura and Mahon 2011), C. chinensis can become established rapidly within new water bodies. ...
Non-native species that become invasive threaten natural biodiversity and can lead to socioeconomic impacts. Prediction of invasive species distributions is important to prevent further spread and protect vulnerable habitats and species at risk (SAR) from future invasions. The Chinese mystery snail, Cipangopaludina chinensis, native to Eastern Asia, is a non-native, potentially invasive, freshwater snail now widely established across North America, Belgium, and The Netherlands. This species was first reported in Nova Scotia, eastern Canada in 1955, but was not found to be established until the 1990s and now exists at high densities in several urban lakes. Nonetheless, the presence and potential distribution of this species in Nova Scotia remains unknown. Limited resources make it difficult to do a broad survey of freshwater lakes in Nova Scotia, however a species distribution probability model has the potential to direct focus to priority areas. We apply a random forest model in tandem with a combination of water quality, fish community, anthropogenic water use, and geomorphological data to predict C. chinensis habitat in Nova Scotia (NS), Canada. All predicted probabilities of suitable C. chinensisi habitats in Nova Scotia were > 50% and include Cape Breton Island, the Nova Scotia-New Brunswick border, and the Halifax Regional Municipality. Suitable habitats predicted for C. chinensis overlap with many SAR habitats, most notably brook floater mussel, Alasmidonta varicosa, and yellow lampmussel, Lampsila cariosa. Our results indicate that C. chinensis could become widespread throughout NS, appearing first in the aforementioned areas of highest probability. Further research is required to test C. chinensis ecological thresholds in order to improve the accuracy of future species distribution and habitat models, and to determine C. chinensis impacts on native freshwater mussel populations of conservation concern.
... On the surface of the open upper intertidal mudflat, C. cingulata has very limited access to shaded refugia to escape from heat during emersion. Due to the marked decrease in temperature with sediment depth (de Wilde and Berghuis, 1979;Koh and Shin, 1988;Zhang et al., 2020), burying into mud is an important response for surviving this harsh environment, as in the case of other muddy shore species (Rebach, 1974;Unstad et al., 2013;Zhang et al., 2020). In contrast to C. cingulata, C. largillierti prefers to aggregate around rocks on the upper intertidal shore and seldomly buries into mud. ...
Temperature plays a major role in controlling species' distributions, and small-scale variation in the thermal environment are potentially an important factor that governs distributions on a local scale. For untangling the roles of behavioral and physiological adaptations on species' distribution at a small-scale level, we carried out a comparative study of two mudflat snails (genus Cerithidea) by determining these congeners' burying behavior, lethal temperature, cardiac performance and heat-shock protein (hsp70) gene expression. These two sympatric snails occupy different microhabitats on the upper intertidal mudflat. During periods of emersion, C. cingulata inhabits the open mudflat and C. largillierti usually aggregates around small rocks on the upper intertidal mudflat. Our results indicate that the two Cerithidea congeners show different behavioral and physiological responses to high temperature. Compared to C. largillierti, C. cingulata prefers to bury into the mud, has a higher thermal limit and a higher level of inducible expression of hsp70 mRNA, implying important roles of behavioral and physiological adaptations to the harsh thermal environment on the open mudflat. Furthermore, results of generalized additive modelling (GAM) analysis of cardiac performance and coefficient of variation (CV) of hsp70 mRNA expression showed high inter-individual variation in C. cingulata. These results highlight the importance of behavioral and physiological adaptions in sympatric species' distributions on the mudflat and help to shed light on the mechanisms of how small-scale differences in the thermal environment shape sympatric species’ distributions.
... Особенностью вивипарид является живорождение, отрождаются жизнеспособные моллюски уже покрытые раковиной, что существенно увеличивает их шансы на выживание и повышает репродуктивные возможности вида. К размножению живородки приступают уже в первый год жизни, число зародышей варьирует в зависимости от размеров самки и может достигать 85 эмбрионов на одну самку [Жадин, 1928;Stephen et al., 2013]. ...
... For application of copper sulphate and rotenone in aquatic ecosystems in the Netherlands an exemption from the Dutch law on crop protection and biocides is required . Experimental drawdowns resulting in air exposure of B. chinensis have proven to be an ineffective control measure as this species can withstand long periods of desiccation by closing its operculum and its burrowing behaviour (Havel 2011;Unstad et al. 2013;Havel et al. 2014). In Missouri (USA) manual removal was performed using volunteer snorkelers and scuba divers (Hanstein 2012), resulting in the removal of a large amount of mainly adult snails. ...
The Chinese mystery snail, Bellamya (Cipangopaludina) chinensis, was recorded for the first time in 2007 in the Netherlands. By 2016, twelve water bodies (mostly riverine ecosystems) had been colonized by this freshwater snail. These records were the first known introductions of this alien species in the European Union (EU). Insight into the invasiveness and (potential) risks of ecological, socio-economic and public health effects of B. chinensis in Europe is urgently needed due to multiple introductions, permanent establishment and continuing secondary spread. A field survey was carried out to determine dispersal rate, habitat conditions and population characteristics of B. chinensis in the floodplain Eijsder Beemden along the Meuse River. The natural dispersal rate in this area was 0.1 km/yr and the average population density was 0.33 individuals/m2. This species has colonized several floodplain lakes that are hydrologically connected to the Meuse River. New introductions and colonization of the main channels of large rivers are expected to accelerate the dispersal of this species through water flow and shipping vectors. A risk assessment of B. chinensis was performed using the Harmonia+ protocol. Evidence of deliberate and unintentional introductions led to a high score for introduction risk. Risk of establishment was also assessed as high. The risk assessment resulted in a medium score for spread risk due to dispersal by human action. The assessed impact on plant targets or animal targets was very low.
A medium risk was assigned to impacts on environmental targets. Risk of impacts on human targets received a low score. The overall invasion risk was classified as high and environmental impact was medium, resulting in a medium overall risk score. Regulation of B. chinensis trade and an increase in public awareness about its impact are required to prevent new introductions and further spread of this species in Europe. Moreover, there is an urgent need for research concerning the effects of B. chinensis on native biodiversity and ecosystem functioning, and cost-effective management of this species (e.g., eradication, population control and containment measures).
The freshwater Japanese mystery snail ( Heterogen japonica ) was introduced to the United States in the early 1900s and has since established populations throughout the continent. The species has ovoviviparous reproduction (i.e., eggs hatch within the mother and develop inside before being released as juveniles), which is one reason it has been successful. Despite its wide geographic range, little is known about its physiological tolerances. For example, high salinities and temperatures may limit its spread, and determining the species’ tolerance to these environmental factors is crucial to predict its possible range expansion. To test this, 600 juvenile H. japonica (average shell length: 6.0mm, range: 4.5–8.3mm) were collected from 28 females from a lake in Virginia, USA and placed in a fully crossed design to test the interaction between salinity (0.2 and 2 PSU) and temperature (25 °C, 34 °C and 38 °C). Juveniles were monitored for mortality over two weeks. Kaplan–Meier survival analyses determined median survival probabilities, and generalized linear models compared differences in mean survival. All juveniles in 25 °C (except one in 0.2 PSU) survived (N=199/200), and all juveniles in 38 °C died by the end of 14 days (N=200), irrespective of salinity. However, juveniles kept at 38 °C showed higher early (≤4 days) mortality in 0.2 PSU, but lower early mortality in 2 PSU. Importantly, juveniles in 2 PSU survived for ≥2 days (N=294/300) across all temperatures, indicating that there may be scope for expansion through estuaries. Future work should examine temperatures between 34 and 38 °C and salinities above 2 PSU to understand the extent of covariance between salinity and temperature and create mathematical models to estimate survivability and spread.
Over the past decade, mounting evidence has shown the pervasive and escalating harmful impacts of invasive alien species on native species and ecosystems. Thousands of non-native species are established in the United States and many more worldwide. Few areas appear immune to invasions, some of which unfold over decades to centuries as species' ranges slowly expand across the landscape. A plethora of ecological effects have been attributed to invasive species, and other global change processes and widespread habitat destruction will likely multiply these effects. Many conservationists now consider invasive species among the top threats to biological diversity and are grappling with identifying pragmatic, effective solutions. They know that the future will involve mixed assemblages of native and non-native species and have important questions about which invasive species to tackle and which ones to ignore, and even whether to deliberately introduce certain species for restoration. Addressing these issues will push hard against the limits of today's ecological knowledge and our ability to predict the long-term ecological consequences of such decisions. Better envisioning the conservation goals, though, could help to guide the science.
In the 20 years since zebra mussels (Dreissena polymorpha) first appeared in North America, they have become one of our most widespread and abundant freshwater animals, and have fundamentally transformed freshwater food webs and biogeochemistry. Indeed, few human impacts on North American fresh waters have been greater or more far-reaching than the arrival of this single species. Nevertheless, ecological research has been uneven, and important research questions remain unanswered, especially concerning the long-term, large-scale effects of the invasion. Economic impacts have also been incompletely estimated, although they already exceed $100 million. We know little about the extent to which large outreach programs about zebra mussels have changed public knowledge, attitudes, or behaviors, and there are still substantial gaps in policies to curb the establishment, spread, and impacts of species like zebra mussels. Scientific, educational, and policy responses to the zebra mussel invasion highlight our successes and limitations concerning alien species in general.
We report the results of five experiments performed during periods of lowered river water level in Pool 26 of the Mississippi River. Four experiments compared survivorship of zebra mussels (Dreissena polymorpha) and unionid mussels (Unionidae). Under mild spring conditions (March), survivorship of zebra mussels was similar to that of unionid mussels, but during summer (July) survivorship of zebra mussels was lower than that of unionid mussels. Survivorship of zebra mussels was greatest when attached to native unionids, compared with detached zebra mussels and zebra mussels attached rocks. A fifth experiment compared survivorship of 10 species of unionid mussels after 24 hours of aerial exposure. In general, survivorship of thick-shelled species, such as Amblema plicata, was greater than survivorship of thin-shelled species, such as Potamilus ohiensis. The experiments conducted suggest that drawdowns during warm summer conditions could have a profound, negative influence on zebra mussel demography and distribution. In contrast, unionid mussel survival was unaffected by aerial exposure of up to 24 hours during a midsummer drawdown. © 1997 John Wiley & Sons, Ltd.
The Chinese mystery snail (Bellamya chinensis) is an aquatic invasive species found throughout the USA. Little is known about this species’ life history or ecology, and only one population estimate has been published, for Wild Plum Lake in southeast Nebraska. A recent die-off event occurred at this same reservoir and we present a mortality estimate for this B. chinensis population using a quadrat approach. Assuming uniform distribution throughout the newly-exposed lake bed (20,900 m²), we estimate 42,845 individuals died during this event, amounting to approximately 17% of the previously-estimated population size of 253,570. Assuming uniform distribution throughout all previously-reported available habitat (48,525 m²), we estimate 99,476 individuals died, comprising 39% of the previously-reported adult population. The die-off occurred during an extreme drought event, which was coincident with abnormally hot weather. However, the exact reason of the die-off is still unclear. More monitoring of the population dynamics of B. chinensis is necessary to further our understanding of this species’ ecology.
The Chinese mystery snail (Bellamya chinensis) is a non-indigenous, invasive species in freshwater ecosystems of North America. We provide fecundity estimates for a population of these snails in a Nebraska reservoir. We dissected 70 snails, of which 29 were females. Nearly all female snails contained developing young, with an average of 25 young per female. Annual fecundity was estimated at between 27.2 and 33.3 young per female per year. Based on an estimated adult population and the calculated fecundity, the annual production for this reservoir was between 2.2 and 3.7 million young.
The Chinese mystery snail (Bellamya chinensis) is an aquatic invasive species in North America. Little is known regarding this species' impacts on freshwater ecosystems. It is be lieved that population densities can be high, yet no population estimates have been reported. We utilized a mark-recapture approach to generate a population estimate for Chinese mystery snail in Wild Plum Lake, a 6.47-ha reservoir in southeast Nebraska. We calculated, using bias-adjusted Lincoln-Petersen estimation, that there were approximately 664 adult snails within a 127 m2 transect (5.2 snails/m2). If this density was consistent throughout the littoral zone (<3 m in depth) of the reservoir, then the total adult population in this impoundment is estimated to be 253,570 snails, and the total Chinese mystery snail wet biomass is estimated to be 3,119 kg (643 kg/ha). If this density is confined to the depth sampled in this study (1.46 m), then the adult population is estimated to be 169,400 snails, and wet biomass is estimated to be 2,084 kg (643 kg/ha). Additional research is warranted to further test the utility of mark-recapture methods for aquatic snails and to better understand Chinese mystery snail distributions within reservoirs.
Field collections at more than 2900 sites and the examination of many museum collections and literature allowed me to map the historical and current distribution of several freshwater molluscan faunal groups in the Intermountain region of the United States (Great Basin, Colorado River drainage basin, and upper Snake River sub-basin). Historical and current records show that Margaritifera falcata, Anodonta californiensis, and Ferrissia rivularis have drainage-specific distributions, while Valvata utahensis has a specific drainage pattern, and V. californica (new combination) has a dispersed pattern. Shell morphometric data of Valvata and Ferrissia show extensive shell variation between and within populations. Current surveys show that these molluscan populations have been reduced since the colonization by European descendants over the last 150 years. Margaritifera falcata was found to be extirpated from eastern California, Nevada, and Utah and was common in only 1 stream. Anodonta californiensis populations of 10 or more individuals occurred in only 2 of 13 drainages, as well as in 1 isolated spring. Valvata californica was extirpated in 7 of 10 lakes. Ferrissia rivularis was very rare in 6 of 12 drainages. Range declines among these fauna are thought to be related to alterations of habitat caused by grazing, irrigation, and urbanization, as well as the intensive management of sport fish in these waters.
We report the results of five experiments performed during periods of lowered river water level in Pool 26 of the Mississippi River. Four experiments compared survivorship of zebra mussels (Dreissena polymorpha) and unionid mussels (Unionidae). Under mild spring conditions (March), survivorship of zebra mussels was similar to that of unionid mussels, but during summer (July) survivorship of zebra mussels was lower than that of unionid mussels. Survivorship of zebra mussels was greatest when attached to native unionids, compared with detached zebra mussels and zebra mussels attached rocks. A fifth experiment compared survivorship of 10 species of unionid mussels after 24 hours of aerial exposure. In general, survivorship of thick-shelled species, such as Amblema plicata, was greater than survivorship of thin-shelled species, such as Potamilus ohiensis. The experiments conducted suggest that drawdowns during warm summer conditions could have a profound, negative influence on zebra mussel demography and distribution. In contrast, unionid mussel survival was unaffected by aerial exposure of up to 24 hours during a midsummer drawdown. (C) 1997 John Wiley & Sons, Ltd.
First detected in the United States in Idaho's Snake River in 1987, the New Zealand mud snail (NZMS), Potamopyrgus antipodarum, was discovered in Olympia Washington's Capitol Lake in 2009. The snail is not native to North America and may be capable of adversely impacting native species diversity and food web dynamics in aquatic ecosystems. In this study, we evaluated the effect of lowering the lake level during freezing weather on the survival of NZMSs. Both generalized linear models with link function logit and nonlinear mixed effects models were used to investigate the rates of detection and survival with four temporal and environmental predictor variables. The rate of detection of NZMSs was affected by substrate depth and proximity to shore. The location of sample stations (upshore versus offshore), substrate depth, and elapsed time between collection from the field and laboratory processing did not affect survival rates. The survival rate of NZMSs decreased rapidly with time and the predicted survival rate at the conclusion of the freezing episode was 1.8%. The results indicate that lowering the water level during freezing weather can be a highly effective means for controlling the distribution and abundance of NZMSs and reducing the risk of their spread to other water bodies.