Exotic Snail Research Articles

Distribution and occurrence of the exotic digenetic trematode (Centrocestus formosanus), its exotic snail intermediate host (Melanoides tuberculatus), and rates of infection of fish in springs systems in western Texas

We examined the distribution and co-occurrence of the exotic digenetic trematode Centrocestus formosanus, its exotic intermediate host the red-rim melania snail Melanoides tuberculatus, and rates of infection of fish in 10 spring systems throughout western Texas during 1999 and 2011. Four of the spring systems (East Sandia Springs, Independence Creek, Big Bend National Park Refugium Pond, and Clear Creek) did not contain red-rim melania snails in 1999 and 2011. Four spring systems that were populated with snails (San Felipe Creek, San Solomon Springs, Phantom Lake, and Diamond Y Springs) contained the trematode and were positive for branchial infection in fish except Diamond Y Springs which contained uninfected snails and fish. Since 1999, two additional spring systems, Pinto Creek and Devils River, contained the trematode. We found a high prevalence of branchial infection for fish collected regardless of species. Seventeen of the 21 species of fish collected from the spring systems were positive for infection by trematodes. On average, the most infected genera were Micropterus and Lepomis followed in decreasing order by Etheostoma, Dionda, Astyanax, Cichlasoma, Notropis, Cyprinella, Gambusia, Ictalurus, and Hypostomus. Seven state-listed or federally listed species we collected had a relatively high percentage (mean = 52%) of developing metacercarial cysts except E. grahami (mean = 14%). Our laboratory study suggests that, for Gambusia, rates of infection by trematodes are species–specific with G. affinis having significantly more cysts than did G. nobilis and G. gaigei. Our work extended the documented range of red-rim melania snails and C. formosanus in Texas.

The potential ecological impact of the exotic snail Pomacea canaliculata on the Thai native snail Pila scutata

ABSTRACT: The aims of this study were to compare food consumption, growth rates, time to reach food, and food preferences of the golden apple snail (Pomacea canaliculata) and the Thai native snail (Pila scutata). The eggs of the two species collected from natural habitats were hatched in the laboratory. Snails of one month were raised together and separately to determine growth rates and food consumption. It was found that the growth rate of P. canaliculata was significantly faster than that of P. scutata when both were raised together and when they were raised separately. Both snails grew better when raised separately. P. canaliculata consumed significantly more food than P. scutata. When raised separately, P. canaliculata crawled to food at a significantly faster rate than P. scutata. On average, P. canaliculata and P. scutata took 8.2± 3.2 and 15.1± 3.1 min, respectively, to reach the food offered. To test for food preferences, four local species of aquatic plants, namely Hydrilla verticillata, Nymphaea lotus, Salvinia cucullata, and Alternanthera triandra were provided to both snails. It was discovered that P. canaliculata consumed all the four different food species offered. In contrast, P. scutata tended to feed on S. cucullata rather than the other species. It is concluded that P. canaliculata was superior to P. scutata in terms of growth rates, food consumption, and was also non-selective for food and therefore there is no doubt that in a shared habitat, P. canaliculata will influence P. scutata.

Rapid population growth countered high mortality in a demographic study of the invasive snail, Melanoides tuberculata (Müller, 1774), in Florida

Melanoides tuberculata, an exotic thiarid snail that originated in the Middle East, eastern Africa, and Southeast Asia, has invaded subtropical and tropical areas worldwide. This study provided a detailed picture of the characteristics of a population in central Florida. We collected 40 specimens of Melanoides tuberculata from a cool spring and cultured them and 54 of their offspring in the laboratory for 7 and 10 months, respectively. For both the adults and their F1 offspring, weekly or bimonthly measurements of individuals and counts of offspring produced estimates of growth, age at first reproduction, offspring production, and survival. From these measurements, we produced estimates of birth and death rates and a growth curve using a monomolecular model. We estimated predation rates on the snails with a three-day incubation of small (1–4 mm) M. tuberculata with crayfish in the laboratory. Finally, we produced a static life table from measurements of ~2,200 specimens of M. tuberculata collected from the spring. Growth and reproduction measurements from the laboratory indicated that the snails grew rapidly and were prolific. Only initial size significantly explained any variation in the growth of individuals and only first clutch size explained any variation in fecundity. Nonpredatory mortality in the laboratory was low, but crayfish-induced mortality was high. The life table analysis suggested that the spring population was stable and that mortality was extremely high on the smallest individuals, such as those used in the crayfish predation rate measurements, and on the largest individuals. Therefore, the potential of M. tuberculata to invade new habitats and quickly establish populations may be the result of its high population growth rate, but its population growth may be checked by local predators, such as crayfish and perhaps snail-eating turtles and raccoons.

The presence of an exotic snail, Pomacea maculata, inhibits growth of juvenile Florida apple snails, Pomacea paludosa

The presence of an exotic snail, Pomacea maculata, inhibits growth of juvenile Florida apple snails, Pomacea paludosa

An Artificial Perch to Help Snail Kites Handle an Exotic Apple Snail

In the United States, the Snail Kite (Rostrhamus sociabilis plumbeus) is a federally endangered species and restricted to the wetlands of south-central Florida where the current population numbers less than 1,500. The Snail Kite is an extreme dietary specialist, previously feeding almost exclusively on one species of snail, the Florida Apple Snail (Pomacea paludosa). Within the past decade, an exotic species of apple snail, the Island Apple Snail (Pomacea insularum), has become established on lakes in central Florida. Island Apple Snails are larger than the native Florida Apple Snails, and Snail Kites handle the exotic snails less efficiently. Juvenile Snail Kites, in particular, have lower daily energy balances while feeding on Island Apple Snails. An inexpensive, easy-to-construct platform was developed that would provide Snail Kites with a flat, stable surface on which to extract snails. The platform has the potential to reduce the difficulties Snail Kites experience when handling exotic snails, and may benefit the Snail Kite population as a whole. Initial observations indicate that Snail Kites use the platforms frequently, and snails extracted at the platforms are larger than snails extracted at other perches.

Fecundity and Survival Advantages of an Exotic Gastropod Compared to a Native Species

Abstract: In Argentina the exotic snail Physa acuta Draparnaud, 1805 is predominant in environments previously inhabited by the native species Stenophysa marmorata Guilding, 1828, raising the question of whether this could have occurred because of differences in survival or reproductive strategies. To analyze the life cycle of these two species, I used the horizontal—life-table method and considered the number and proportion of viable of eggs per oviposition. Although both species suffered a high degree of mortality during the first weeks after oviposition, both the rate and the force of mortality was much greater during the reproductive period, so that the survival curve was not as markedly concave as with other gastropods. Physa acuta survived longer than S. marmorata, began its reproductive period earlier, and had a longer and more continuous reproductive stage. The number of ovipositions per snail was not different between the two species; but since the mean number of eggs per oviposition was higher i...

Cercarial Dermatitis Transmitted by Exotic Marine Snail

Cercarial dermatitis (swimmer's itch) is caused by the penetration of human skin by cercariae of schistosome parasites that develop in and are released from snail hosts. Cercarial dermatitis is frequently acquired in freshwater habitats, and less commonly in marine or estuarine waters. To investigate reports of a dermatitis outbreak in San Francisco Bay, California, we surveyed local snails for schistosome infections during 2005-2008. We found schistosomes only in Haminoea japonica, an Asian snail first reported in San Francisco Bay in 1999. Genetic markers place this schistosome within a large clade of avian schistosomes, but do not match any species for which there are genetic data. It is the second known schistosome species to cause dermatitis in western North American coastal waters; these species are transmitted by exotic snails. Introduction of exotic hosts can support unexpected emergence of an unknown parasite with serious medical or veterinary implications.

Erratum to: Linking calcification by exotic snails to stream inorganic carbon cycling

Erratum to: Linking calcification by exotic snails to stream inorganic carbon cycling

Linking calcification by exotic snails to stream inorganic carbon cycling

Biotic calcification is rarely considered in freshwater C budgets, despite calculations suggesting that calcifying animals can alter inorganic C cycling. Most studies that have quantified biocalcification in aquatic ecosystems have not directly linked CO(2) fluxes from biocalcification with whole-ecosystem rates of inorganic C cycling. The freshwater snail, Melanoides tuberculata, has achieved a high abundance and 37.4 g biomass m(-2) after invading Kelly Warm Springs in Grand Teton National Park. This high biomass suggests that introduced populations of Melanoides may alter ecosystem processes. We measured Melanoides growth rates and biomass to calculate the production of biomass, shell mass, and CO(2). We compared Melanoides biomass and inorganic C production with ecosystem C pools and fluxes, as well as with published rates of CO(2) production by other calcifying organisms. Melanoides calcification in Kelly Warm Springs produced 12.1 mmol CO(2) m(-2) day(-1) during summer months. We measured high rates of gross primary productivity and respiration in Kelly Warm Springs (-378 and 533 mmol CO(2) m(-2) day(-1), respectively); CO(2) produced from biocalcification increased net CO(2) production in Kelly Warm Springs from 155 to 167 mmol CO(2) m(-2) day(-1). This rate of CO(2) production via biocalcification is within the published range of calcification by animals. But these CO(2) fluxes are small when compared to ecosystem C fluxes from stream metabolism. The influence of animals is relative to ecosystem processes, and should always be compared with ecosystem fluxes to quantify the importance of a specific animal in its environment.

Effects of an exotic prey species on a native specialist: Example of the snail kite

Despite acknowledging that exotic species can exhibit tremendous influence over native populations, few case studies have clearly demonstrated the effects of exotic prey species on native predators. We examined the effects of the recently introduced island apple snail ( Pomacea insularum) on the foraging behavior and energetics of the endangered snail kite ( Rostrhamus sociabilis plumbeus) in Florida. We conducted time-activity budgets: (i) on kites foraging for native Florida apple snails ( Pomacea paludosa) in major wetland units within the kites’ range that had not been invaded by the exotic island apple snail and (ii) on kites foraging for exotic apple snails in Lake Tohopekaliga, the only major wetland utilized by the snail kite that had suffered a serious invasion of P. insularum. When foraging for P. insularum, snail kites dropped a greater proportion of snails, and they experienced increased handling times and decreased consumption rates; however, kites foraging for P. insularum also spent a smaller proportion of the day in flight. Estimates of net daily energy balances between kites feeding on P. insularum versus P. paludosa were comparable for adults, but juveniles experienced energetic deficiencies when feeding on the exotic snail. Due to this discrepancy, we hypothesize that wetlands invaded by P. insularum, such as Lake Tohopekaliga, may function as ecological traps for the snail kite in Florida by attracting breeding adults but simultaneously depressing juvenile survival. This study highlights the conservation implications and importance of elucidating the effects that exotic species have on native specialists, especially those that are endangered, because subtle influences on behavior may have significant population consequences.

Use of Ice‐Water and Salt Treatments to Eliminate an Exotic Snail, the Red‐Rim Melania, from Small Immersible Fisheries Equipment

AbstractIce‐water and salt treatments were evaluated for disinfection of small immersible fisheries equipment contaminated with a nonindigenous tropical snail, the red‐rim melania Melanoides tuberculatus. This introduced species can displace native snails and transmit trematodes directly to fish and indirectly to other animals, including humans. The red‐rim melania has a well‐developed operculum that protects it from desiccation and allows it to remain viable for days on dry fisheries equipment. Treatments were produced by adding 10 kg of salt and 33.3 kg of ice to 66.6 L of water (salt–ice‐water [SIW]) or by adding 40 kg of ice to 32 L of water (ice‐water only [IW]) and were tested for various periods (0.17 min to 24 h) to find exposures that would kill 100% of the treated snails. Temperatures produced in the test containers ranged from −6.3°C to −2.4°C for SIW and from 0°C to 4.9°C for IW. The survival of snails in saltwater‐only (SW) treatments (10 kg of NaCl in 100 L of water) was also tested. Three size‐groups of snails were tested: 2–4‐, 15–20‐, and 30–40‐mm shell heights. Exposure periods that resulted in an estimated 0% survival for the 15–20‐mm snails were 35.8 min for SIW, 179.6 min for IW, and 423.6 min for SW. The calculated amounts of time (regression analysis) required to kill 100% of the three size‐groups of snails exposed to the SIW treatment were 17.8 min for 30–40‐mm snails, 35.8 min for 15–20‐mm snails, and 67.5 min for 2–4‐mm snails.

Occurrence of the exotic freshwater snail Melanoides tuberculatus (Mollusca: Gastropoda: Thiaridae) in an estuary of north-eastern Brazil

Occurrence of the exotic freshwater snail Melanoides tuberculatus (Mollusca: Gastropoda: Thiaridae) in an estuary of north-eastern Brazil

Biomphalaria havanensis Identified as a Potential Intermediate Host for the Digenetic Trematode Bolbophorus damnificus

AbstractThe digenetic trematode Bolbophorus damnificus has been associated with mortalities in commercial channel catfish Ictalurus punctatus in the Mississippi Delta. In the life cycle of B. damnificus, the only confirmed first intermediate host is the ram's horn snail Planorbella trivolvis. Recently, the exotic snail Biomphalaria havanensis has been isolated in several channel catfish ponds in the Mississippi Delta. The aim of this study was to determine whether this invasive snail species could also serve as a first intermediate host in the B. damnificus life cycle. Bolbophorus damnificus ova were collected from an American white pelican Pelecanus erythrorhynchos that had been artificially infected with B. damnificus metacercariae; the ova were then introduced into an aquarium with parasite‐negative B. havanensis. Bolbophorus damnificus cercariae (confirmed by polymerase chain reaction) were detected in B. havanensis 45 d after exposure to B. damnificus ova. The snails continued to shed B. damnificus cercariae throughout the 80‐d postexposure examination period. Before this research, the only reported natural B. damnificus infection of snails involved P. trivolvis. This study indicates that the range of snail hosts is broader than previously suspected. A survey should be implemented to identify additional snail species that can serve as hosts for B. damnificus. Further research should determine whether B. havanensis is a natural host for B. damnificus, and if so the prevalence of B. havanensis in commercial channel catfish ponds should be assessed.

Application of Household Disinfectants to Control New Zealand Mudsnails

AbstractThe New Zealand mudsnail Potamopyrgus antipodarum was recently discovered in Colorado, thereby expanding its invasion of the western United States. This exotic snail may invade streams through transport on angling gear and fishery equipment. Previous studies have demonstrated that some household cleaning products are lethal to New Zealand mudsnails and can be used to disinfect waders and boots. Two disinfectants, antibacterial Formula 409 All‐Purpose Cleaner and Sparquat 256, were compared as potential control agents. Snails were submersed for 5 or 10 min in one of two Formula 409 solutions (50% or 100%) or one of three Sparquat 256 solutions (1.6, 3.1, or 4.7%). We used distilled water as the control treatment. Snail mortality at 48 h and 56 d after exposure was evaluated. Our findings suggest that the current recommendation (5‐min application of 50% Formula 409) is not sufficient; half of the snails survived this treatment in our study. In contrast, a 10‐min exposure to 100% Formula 409 or to a Sparquat 256 solution of at least 3.1% resulted in 100% snail mortality. In addition to its effectiveness in controlling New Zealand mudsnails, Sparquat 256 has also proven useful as a disinfectant for whirling disease spores and other fish pathogens.

Density effects of native and exotic snails on growth in juvenile apple snails Pomacea paludosa (Gastropoda: Ampullariidae): a laboratory experiment

Pomacea paludosa (native Florida apple snail) is found in wetlands in the southeastern United States. Pomacea insularum is an exotic apple snail which has invaded wetlands in Florida and co-occurs with P. paludosa. The effect of changes in density on growth in native juvenile snails was studied by manipulating native juvenile density, native adult density and exotic adult density in a set of laboratory experiments. Growth decreased when native juvenile densities (without adults) increased from four to eight snails per 38-l aquarium. The presence of adults of either species decreased juvenile growth and also decreased juvenile survival. One exotic adult had the equivalent effect of three to four native adults. Based on the response of native juveniles to exotic adults, populations of the native apple snail P. paludosa could be negatively impacted by expansion of the exotic snail P. insularum.

Habitat influences snail community structure and trematode infection levels in a spring-fed river, Texas, USA

The spring-fed Comal River in Texas, USA, has been impounded and channelized resulting mainly in a lentic environment with four headwater spring runs. We sampled two spring runs (lotic sites) and two lentic sites seasonally from April 2001 through April 2002 to assess (1) co-occurrence of native and exotic snail species (as determined by interspecific association), (2) the importance of habitat conditions in structuring relationships among these species, and (3) the distribution of snails infected with exotic trematode parasites. Three exotic and four endemic species of aquatic snails were collected, but only Elimia comalensis (Prosobranchia: Pleuroceridae, native), Melanoides tuberculatus, and Tarebia granifera (Prosobranchia: Thiaridae, exotic) were in sufficient densities for further analyses. Tarebia granifera was positively associated with both M. tuberculatus (χ2 = 18.5, P < 0.001) and E. comalensis (χ2 = 7.3, P < 0.01), although the co-occurrence between the two exotics was much stronger. Melanoides tuberculatus and E. comalensis exhibited a strong, negative association (χ2 = 10.9, P < 0.001). The weaker co-occurrence between E. comalensis with the thiarids appeared to be driven by differences in habitat use by the thiarids and native E. comalensis. In lentic habitats, densities of M. tuberculatus and T. granifera were similar but differed significantly from E. comalensis whose densities were 200 times less than the exotic snails. In lotic spring runs, densities of T. granifera and E. comalensis were similar, but differed significantly from M. tuberculatus whose densities were 10 times fewer. Lower densities of M. tuberculatus and T. granifera in habitat conditions common to the spring runs may explain why exotic snail interactions were less with the native E. comalensis than with each other. The native snail, E. comalensis, was not infected with any trematodes, while 6.1% of M. tuberculatus and 4.8% of T. granifera were infected with exotic trematodes. Distributions of infected snails were aggregated; such that most infected snails were found in lentic habitats with silt substrates and moderate to high levels of detritus. Continued declines in spring-flows due to aquifer withdrawals and droughts will increase lentic habitats that may lead to increased densities of T. granifera and M. tuberculatus and their concomitant parasites.

Linking Exotic Snails to Carbon Cycling in Kelly Warm Springs, Grand Teton National Park

Biotic calcification has yet to be considered in most freshwater carbon budgets, despite previous calculations that suggest the importance of calcifying animals in altering inorganic carbon cycling. The freshwater snail, Melanoides tuberculata, has achieved a high abundance and a biomass of 34.2 g AFDM m-2 after invading Kelly Warm Springs in Grand Teton National Park approximately five years ago. This high biomass suggests that introduced populations of Melanoides may alter ecosystem processes. We measured Melanoides growth rates and biomass to calculate the production of biomass, shell mass, and C02 for comparison with ecosystem carbon pools and fluxes. Melanoides calcification in Kelly Warm Springs produced up to 10.4 mmol C02 m-2 day-1 during summer months. Despite extremely high primary production and respiration in Kelly Warm Springs (-379 mmol C02 m-2 day-1 and 445 mmol C02 m-2 day-1 , respectively), C02 produced from biotic calcification increased total C02 production in Kelly Warm Springs from 65.9 to 76.3 mmol C02 m-2 day-1 . This rate of C02 production via biotic calcification is within the range of those previously calculated for freshwater systems and suggests the importance of considering the role of calcification in inorganic carbon budgets for areas dominated by calcifying organisms.

Spread of an exotic fish-gill trematode

Centrocestus formosanus, the gill trematode, has caused serious losses among fish raised by tropical fish producers since the early 1980s and is believed to be harmful to wild fish populations, including the federally listed endangered fountain darter (Etheostoma fonticola), in the Comal River near San Marcos, Texas. The parasite appears to infect in many fishes from Hawaii, Florida, Texas, and Utah. The gill trematode has a complex life cycle involving definitive hosts (aquatic birds and occasionally some mammals) and intermediate hosts (aquatic snails and several fish species). In the United States, the green heron (Butorides virescens) and the great egret (Ardea alba) serve as definitive hosts. The first intermediate host, the red-rim melania (Melanoides tuberculatus), an exotic snail, has been found in 15 southern and western states. This snail exhibits resistance to desiccation, molluscicides, and disinfectants and has been documented to out-compete established mollusks. Both the gill trematode and its exotic snail host continue to spread in the United States.

INVADING HERBIVORY: THE GOLDEN APPLE SNAIL ALTERS ECOSYSTEM FUNCTIONING IN ASIAN WETLANDS

We investigated the effects of an exotic snail, the golden apple snail (Pomacea canaliculata) on biodiversity and ecosystem functioning in tropical wetland ecosystems. This large snail (up to 80-mm shell height) has invaded large parts of Southeast Asia during recent decades. A survey of natural wetlands in Thailand showed that high densities of the snail were associated with almost complete absence of aquatic plants, high nutrient concentrations, and high phytoplankton biomass, that is, a complete shift in both ecosystem state and function. A field experiment demonstrated that grazing by the snail can cause the loss of aquatic plants, a change toward dominance of planktonic algae, and thereby a shift toward turbid water. Estimates of biologically fixed nutrients released through snails grazing on aquatic plants revealed that phosphorus releases were sufficient to explain the recorded increase in phytoplankton biomass. Hence, our study demonstrates how an herbivore may trigger a shift from clear water and macrophyte dominance to a turbid state dominated by planktonic algae. This shift and the continuing aggressive invasion of this exotic species are detrimental to the integrity and functioning of wetland ecosystems, and to the services these provide in Southeast Asia.

Exotic Snails Dominate Nitrogen and Carbon Cycling in a Highly Productive Stream

Exotic Snails Dominate Nitrogen and Carbon Cycling in a Highly Productive Stream