Freshwater Molluscs Research Articles

Quantitative PCR (qPCR) assay for the specific detection of the Chinese mystery snail (Cipangopaludina chinensis) in the UK.

Cipangopaludina chinensis Gray 1833 is an East Asian freshwater snail and invasive species in many parts of the world (Global Invasive Species Database, 2022). Within the UK, it was first found at the Pevensey Levels, Sussex, and has since been reported at a second site at Southampton Common, Hampshire. Both sites are designated as Sites of Special Scientific Interest (SSSI) for their wildlife importance. Although the impacts of this species within the UK have not yet been investigated several exotic parasites of the snail have been reported and research suggests that its presence can negatively impact native snail species. This is especially important at the Pevensey Levels due to the presence of the rare freshwater mollusc Anisus vorticulus (Little Whirlpool Rams's-horn snail). Here, we have developed a qPCR-based eDNA assay for the detection of C. chinensis and compared water samples tested for eDNA with results from manual survey of the ditches at the Pevensey Levels. Our eDNA analysis exhibited an overall observed percentage agreement of 80% with a kappa coefficient of agreement between manual and eDNA surveys of 0.59 (95% CI 0.31 to 0.88). Some samples which were qPCR negative for C. chinensis were positive by manual survey, and vice versa revealing the potential for improved overall detection rates when using a combination of manual and eDNA methodologies. eDNA analysis can therefore augment manual survey techniques for C. chinensis as a relatively quick and inexpensive tool for collecting presence and distribution data that could be used to inform further manual surveys and control measures within the ditches.

Composition and distribution of freshwater mollusks in the Pantanal biome, Mato Grosso State, Brazil

Composition and distribution of freshwater mollusks in the Pantanal biome, Mato Grosso State, Brazil

RUSAVA-2, A NEW LOCALITY OF MID-PLEISTOCENE FAUNA AND PALYNOFLORA IN UKRAINE: GEOLOGY, PALAEONTOLOGY, PALAEOGEOGRAPHY AND RELATIVE GEOCHRONOLOGY

This paper reports the results of field geological studies of Rusava-2 section recently discovered in Vinnytsia Region and an examination of the fossil fauna and palynoflora from the locality to provide a deeper and integrated characterisation of the Pleistocene deposits of the Middle Dniester area of Ukraine. Ten taxa of mammals were identified in the alluvial series of the terrace: Equus (Equus) mosbachensis, Bison sp., Cervus sp., Vulpes cf. vulpes, Ochotona ex gr. pusilla, Prolagurus cf. posterius, Arvicola mosbachensis, Mimomys sp., Microtus sp., Allocricetus bursae. The invertebrate fossils represent the ostracod Pseudocandona compressa, 11 species and subspecies of Pleistocene freshwater molluscs, and also include redeposited gastropod shells of the Sarmatian age. A palaeogeographic reconstruction of the development of the terrace complex deposits was made and a relative geological age of the alluvial sediments of the terrace was estimated. The numbering of the Pleistocene terraces of Ukrainian rivers was discussed and the chronocorrelative terraces were proposed to be described as geological bodies with paleontological-chronostratigraphic characteristics. The conducted palynological analysis of the subaerial sediment cover of the terrace suggests a change in vegetation from the meadow-steppe type through coniferous-birch communities to coniferous forests with a small admixture of broadleaved trees. The biostratigraphic analysis indicates the correlation of the subaqueous sediments of the Rusava-2 section with the early Middle Neopleistocene deposits and with the above-floodplain Zavadivka-Dnieper terraces containing the fauna of the Babel therioassociation and flora of the Zavadivka thermochrone.

Efficacy of Molecular Identification Using DNA Barcoding Technique of Freshwater Edible Molluscs from Nagaland, India

Freshwater molluscs are widely utilized for food and medicine in many regions of the world. One such area in India is the northeast, where tribal and economically underdeveloped communities consume freshwater molluscs. Because they are an inexpensive source of protein and offer food security, livelihoods, and medicine, these molluscs are in great demand. In the present work, molecular identification and documentation of the edible gastropods of Nagaland is done. Throughout the twentieth century, identification was based on morphology and anatomy. However, the identification based on morphological structure is challenging due to the existence of cryptic species that shows similar morphology which can lead to erroneous identification of species. Freshwater molluscs shells are highly varied and exhibit convergence evolution and hence may not always accurately indicate systematic boundaries. Thus, DNA bar-coding is a potential method for taxonomic identification process that can mitigate this problem. It uses genetic markers such as cytochrome oxidase I (COI) gene, 16S rDNA and 18S rDNA. In the present study COI mitochondrial gene is used. A fragment of COI gene is sequenced and their DNA is compared to the existing sequences in the genomic library. The sequence is then submitted in NCBI to obtain accession number. A total of 7 species of edible freshwater molluscs belonging to two class bivalvia and gastropoda was collected from local fishery ponds, confined water bodies, rivers, streams, and were identified. The identified species with their accession number is as follows, Lamellidens marginalis (ON209524), Parreysia corrugata (OM074301), Indonaia subclatharata (OM075118), Indonaia caerulea (OM076974), Bellamaya bengalensis (OM056888), Paludomus sp (OM078498), Brotia costula (OM056887). The study provides substantial support for COI's effectiveness as a prime marker for DNA barcoding of Indian edible freshwater gastropods and bivalves.

Updated systematic inventory of the non-marine (land & freshwater) molluscs occurring in the insular territory of Trinidad & Tobago, a physiographic and bioecological extension of Venezuela in the Southeastern Caribbean and immediate Atlantic Ocean

Introduction: Simultaneously with the malacological studies carried about the country of Venezuela (Agudo-Padrón 2023 a-b), since 2014 the “Projeto AM” (Brazil) has carried parallel out taxonomic, bioecological and conservation research of the non-marine (land & freshwater) molluscs present in the immediate neighbor territory insular of “Trinidad & Tobago”. To date, these aspects of the natural history of this geographic region, located in the Northern sector of South America, have been regularly studied. Objective: Substantial updating of this knowledge through an exhaustive review of the regional malacological literature of historical and recent nature available. Methodology: Between 2014 and the present, a sequential review of the species occasionally referred to in the regional literature was carried out, examined from the perspective of the current taxonomy in force. Results and conclusions: Verification and determination of seventy-seven (77) referred taxons, including 64 land/ terrestrial (60 species & 4 subspecies) and 13 aquatic (limnic/ freshwater) forms/ species (9 gastropods & 4 bivalves), taxonomically grouped into thirty-two (32) families and fifty-five (55) genera.

Agricultural Use of Insecticides Alters Homeostatic Behaviors and Cognitive Ability in Lymnaea stagnalis.

Lymnaea stagnalis is an ecologically important, stress-sensitive, freshwater mollusk that is at risk for exposure to insecticides via agricultural practices. We provide insight into the impact insecticides have on L. stagnalis by comparing specific behaviors including feeding, locomotion, shell regeneration, and cognition between snails collected at two different sites: one contaminated by insecticides and one not. We hypothesized that each of the behaviors would be altered in the insecticide-exposed snails and that similar alterations would be induced when control snails were exposed to the contaminated environment. We found no significant differences in locomotion, feeding, and shell regeneration of insecticide-exposed L. stagnalis compared with nonexposed individuals. Significant changes in feeding and shell repair were observed in nonexposed snails inhabiting insecticide-contaminated pond water. Most importantly, snails maintained and trained in insecticide-contaminated pond water did not form configural learning, but this cognitive deficit was reversed when these snails were maintained in insecticide-free pond water. Our findings conclude that insecticides have a primarily negative impact on this higher form of cognition in L. stagnalis. Environ Toxicol Chem 2023;00:1-12. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Construction of the Phylogeny of Freshwater Mollusks by Paleozoogeographic Data Based on the Example of the Family Margaritiferidae (Bivalvia)

Construction of the Phylogeny of Freshwater Mollusks by Paleozoogeographic Data Based on the Example of the Family Margaritiferidae (Bivalvia)

The fragile ecology in Iraq’s Mesopotamian marshlands endangered and restructured by a sharp increase in salinity

In southern Iraq, the Mesopotamian marshes have suffered for decades from a decrease in freshwater input from both rivers Tigris and Euphrates. The Shatt Al-Arab River and East Hammar marsh in southern Iraq were affected by a salt wedge that advanced from the Arabian Gulf during July and August 2018, causing a rapid and sharp increase in salinity levels. A monthly monitoring program has revealed an invasion of saltwater species from the Gulf accompanied by the disappearance of native species of freshwater. Seven submerged aquatic plant species disappeared. Thus, the number of freshwater phytoplankton species decreases. It was found that the quality and quantity of small zooplankton significantly changed, resulting in the disappearance of many freshwater species, and the number of freshwater mollusks significantly decreased. A marsh was invaded by two species of marine shrimp that were previously unrecorded, and native freshwater fish species were drastically affected. East Hammar’s fragile ecology is rapidly shifting from oligosaline to estuarine, devastating an important environmental resource and endangering a culturally unique setting.

Evaluation of metal pollution related to human health risk in freshwater snail Viviparus contectus (Millet, 1813) as a potential bioindicator species in Lake Habitat (Turkey).

Freshwater mollusks are employed as bioindicators for the assessment of water quality in biomonitoring studies since the water quality of natural resources is crucial for humans. The freshwater snail species known as Viviparus contectus (Viviparidae: Gastropoda) is one that people eat. Here, the levels of heavy metals (Cd, Cr, Pb, As, Zn, and Cu) in water and V. contectus samples were determined. An Inductively Coupled Plasma Atomic Emission Spectrometer (ICP-AES, Spectro Arcos, vertical plasma) was used for the analysing the heavy metal concentrations in water and freshwater snail samples. The results of the current investigation demonstrated that freshwater snails accumulated metals in their water and soft tissues in the following orders: Pb > Cr = Zn = Cu = Cd = As and Zn > Cu > Pb > Cd > As = Cr. Autumn was the time of year when higher amounts of heavy metals (As, Cr, Cu, Zn, and Hg) were found. Pb content in the freshwater snail samples was strongly impacted by seasonal fluctuations (P 0.05). For adults, the EDI (estimated daily intake) values were lower than the TDI (tolerable daily intake) values, and the HI (hazard index) values were below 1. Freshwater snail samples had Zn and Pb levels that were over the FAO/WHO, Turkish Food Codex, JECFA, and EC limit values. Except for Pb, the water study shows mean metal concentrations below the USEPA, Turkish Pollution Control Regulation, and World Health Organisation maximum allowed levels. Aquatic ecosystems were negatively impacted by anthropogenic activities overall, and this study can provide a helpful data set for investigations on metallic contamination in water bodies and biomonitoring in freshwater ecosystems.

Global freshwater mollusc invasion: pathways, potential distribution, and niche shift

Global freshwater mollusc invasion: pathways, potential distribution, and niche shift

An extinct species of Tchangmargarya (Gastropoda: Viviparidae) from quaternary lacustrine deposits of a group of vanished lakes in Yunnan, China

ABSTRACT An extinct freshwater molluscan fauna has been discovered from Quaternary lacustrine deposits of a recently vanished group of lakes and surrounding lacustrine deposits in the Luliang Basin, Yunnan Province, China. Three species of Tchangmargarya He, 2013 are dominant and distributed sympatrically here. One of them is new to science. Here we describe the three Tchangmargarya species from the Luliang Basin, including the new species, Tchangmargarya cuan n. sp., and compare the species composition of this fauna with the other extant lacustrine mollusc fauna of Yunnan. The vanished lakes group in Luliang is the first case of sympatric distribution within Tchangmargarya. It is considered to have once been a diversity hotspot of Tchangmargarya and represents a vanished Quaternary lacustrine habitat in Yunnan.

DNA metabarcoding reveals rangewide variation in aquatic diet of a riparian avian insectivore, the Prothonotary Warbler

Abstract Riparian avian insectivores not only depend on terrestrial insect prey but also benefit from the inclusion of aquatic prey during critical life-history periods. Diets identified herein show that Prothonotary Warbler (Protonotaria citrea) nestlings were provisioned with aquatic prey throughout the breeding season across their range, but with variation in prey frequency of occurrence and taxonomy. Anthropogenic activity and climate change may impact the trophic link especially between aquatic and riparian habitats by altering the presence, abundance, and timing of prey availability. Thus, we used DNA metabarcoding of fecal samples to quantify the frequency of occurrence of nestling diet items at 9 sites across their breeding range that differed in expected aquatic prey consumption. We analyzed spatial and temporal differences in the occurrence and multivariate diet assemblages of each prey source. Lepidoptera was the predominant terrestrial prey occurring in diets across space and time, whereas emergent aquatic insects and freshwater mollusks in aquatic diet exhibited greater variation. The frequency of emergent aquatic prey occurrence in nestling diets ranged from 61% to 100% across sites and was greater for early-season nestlings. The seasonal decrease in aquatic prey consumption indicates a potential temporal shift in the nutritional landscape from aquatic to terrestrial prey sources and a possible nutritional phenological mismatch for early nestlings as climate change advances the timing of insect emergence. Our findings also suggest that Prothonotary Warblers respond to environmental variability by consuming alternative prey and argue for future research investigating the extent to which shifting diets have nutritional consequences for riparian nestlings.

Snails on the plate: Edible freshwater molluscs of Northeast India

Snails on the plate: Edible freshwater molluscs of Northeast India

DISTRIBUTION PATTERN OF TREMATODES IN A LARGE SETTLEMENT OF THE PONTO-AZOV MOLLUSK LITHOGLYPHUS NATICOIDES (C. PFEIFFER 1828) (GASTROPODA, HYDROBIIDAE) FROM THE UPPER SECTION OF THE UGLICH RESERVOIR (UPPER VOLGA BASIN)

The Ponto-Azov gastropod mollusk Lithoglyphus naticoides (C. Pfeiffer, 1828) naturalized in the Uglich Reservoir relatively recently (in 2013-2015). The main objective of this study is a comparative analysis of the species diversity and structure of trematode communities in different biotopes, occupied by L. naticoides after the initial phase of its spread in the upper section of this water body (downstream the city of Dubna), characterized by a complex hydrological regime. Approximate coordinates of the geographical center of the large settlement of L. naticoides are 56°53ʹN, 37°25ʹE. It is found that by 2019-2021 the average density of L. naticoides in this settlement reached a consistently high value of about 450 ind./m2. Judging by the variability of shell height in adult mature L. naticoides individuals, even within the same settlement, optimum habitat conditions for this mollusk differ significantly in different biotopes. In a comparative aspect, data from two main hydrobiological sampling locations are considered: in the open part of the reservoir and at the mouth of a large tributary - the Dubna River. It is shown that at both locations the species composition of trematodes in L. naticoides is similar and includes, in particular, parthenitae of Apophallus muehlingi (Jägerskiöld, 1899), Apophallus (= Rossicotrema ) donicus (Skrjabin et Lindtrop, 1919), Parasymphylodora markewitschi Kulakowskaja, 1947, Nicolla skrjabini (Iwanitzky, 1928). However, Sanguinicola volgensis (Razin, 1929) parthenitae, dominant in L. naticoides in the open part of the reservoir, is not found in the sample of mollusks from the mouth of the Dubna River. As compared to the sampling site in the open part of the reservoir, at the mouth of the Dubna River the level of infection with parthenitae of other species is significantly lower: N. skrjabini and P. markewitschi - 7 times, Apophallus spp. - 8 times, Xiphidiocercaria sp. - 13 times. The ratio of males to females among mature individuals of L. naticoides turns out to be close to 1:1, which is usual for many freshwater mollusks. In general, the high occurrence (the infection prevalence - the proportion of infected individuals in the host sample P±SE, %) in the open part of the reservoir indicates the presence of prerequisites for serious outbreaks of helminthoses: Xiphidiocercaria sp. (9.16±2.52%), Apophallus spp. (11.45±2.78%), P. markewitschi (7.63±2.32%), N. skrjabini (7.63±2.32%), S. volgensis (63.36±4.21%). At the same time, according to the data obtained, further spread of L. naticoides in some tributaries of reservoirs in the Upper Volga basin may not have such serious parasitological consequences.

Freshwater Molluscs of Konaseema District, Andhra Pradesh, India

Field surveys conducted in Konaseema district of Andhra Pradesh, especially from river Korangi and Coringa wildlife sanctuary area, revealed 21 species of molluscs belonging to 18 genera and 12 families. Of which 7 species viz., Tricula montana, Stenothyra woodmasoniana, Stenothyra deltae, Stenothyra ornata, Gangetia miliacea, Assiminea francessi and Sermyla riquetii recorded for the first time from the state. The shell characters, distribution and the current status of these species are discussed in this paper.

THE KUYALNYKIAN REGIONAL STAGE OF THE EUXINIAN AREA OF THE EASTERN PARATETHYS AND THE POSSIBILITY OF DETERMINING THE NEOGENE-QUATERNARY BOUNDARY (PIACENZIAN-GELASIAN) IN THE SOUTHERN UKRAINIAN DEPOSITS

The Kuyalnykian regional stage is a stage of evolution of the Euxine Basin of the Eastern Paratethys with its own conditions for the existence of biota. During that time, the estuarine-marine conditions in southern Ukraine prevailed, leading to the development of various geological formations. However, to date, the Kuyalnykian does not have the official status of a regional stratigraphic unit, either in the Neogene stratigraphic scheme of the Eastern Paratethys or in the Neogene stratigraphic scheme of southern Ukraine, also there is no generalised (formal) description of it as a separate regional stratigraphic unit. The lowering of the Neogene–Quaternary boundary from 1.8 to 2.595 Ma led to a discussion about tracing it in the middle of the Kuyalnykian deposits. This study provides a comprehensive analysis of lithofacies, biostratigraphy (molluscs, ostracods, nannofossils, small mammals), palaeomagnetic and paleogeographic data to obtain a holistic view of the stratigraphy of the Kuyalnykian deposits in southern Ukraine. As a result, we acquired a generalized description and regional stratigraphic scheme of the Kuyalnykian, introduced new local stratigraphic units, obtained criteria for tracing the Neogene-Quaternary boundary, and clarified which part of the Kuyalnykian deposits are of Pliocene age and remain on the pre-Quaternary geological maps, and which of them are already of Pleistocene age and should be transferred to the Quaternary geological maps. The Euxine Basin of the Eastern Paratethys during Kuyalnykian was characterised by euryhaline brackish water, freshwater mollusc assemblages, brackish water and freshwater ostracods assemblages that existed in estuarine-marine environments. The Kuyalnykian deposits are divided into two regional substages and be determinated in the Northern Peri-Black Sea Region, Northern Azov Region, the northern part of the Crimean Peninsula and the Kerch Peninsula. We established the following lithostratigraphic units of the Kuyalnykian for southern Ukraine: the Zamorske Formation in the central and eastern part of the Kerch Peninsula; The Mysove Formation in the northwestern part of the Kerch Peninsula and the eastern part of the Crimean Peninsula is partly Kuyalnykian; the upper part of the Bekhtery Formation on the Left Bank of the Lower Dnieper in the Skadovsk and Holoprystan districts belongs to the lower regional substage of the Kuyalnykian; the Kuyalnyk Formation in the Northern Peri-Black Sea region and Northern Azov region, in the north of the Crimean Peninsula belongs to the upper regional substage of the Kuyalnykian. The age of the Kuyalnykian deposits has been determined based on palaeomagnetic and faunal data. The lower boundary of the Kuyalnykian regional stage is 3.6 Ma which coincides with the boundary of the Hilbert-Gauss palaeomagnetic epochs. The boundary between the Lower and Upper substages is 2.59 Ma (the Gauss-Matuyama boundary). The upper boundary of the Kuyalnykian is set at different stratigraphic levels; it dates 1.780 Ma (the upper boundary of the Olduvai Subchron) in the Indol structural facies zone and also ~1.500 Ma (perhaps above the Gils Subchron, based on small mammal data) or ~0.990 Ma (above the Jaramillo Subchron, based on palaeomagnetic data) in the Western and Eastern structural facies zones of the Northern Black Sea Region, the Northern Azov Region, and the Sivash structural facies zone. This diachrony of the upper Kuyalnykian boundary is explained by environmental difference: while in more marine and “deep water” conditions (Indol structural facies zone) the Kuyalnykian molluscs have already changed to “Gurian (sensu lato)”, in relatively remote estuaries (the Northern Black Sea Region, Northern Azov Region) the Kuyalnykian fauna still “survived”. In addition, it should be noted that the palaeomagnetic dates obtained from studied sections of the Northern Black Sea region are not “absolute” and therefore may be reinterpreted in the future.

Unravelling the resilience of the KGK VI population from the Gumelnița site (Romania) through stable isotopes

The Gumelnița site belongs to the Kodjadermen-Gumelnița-Karanovo VI (KGK VI) communities (c. 4700–3900 cal BC) and comprises the tell-type settlement and its corresponding cemetery. This paper reconstructs the diet and lifeways of the Chalcolithic people in the northeastern Balkans using archaeological remains found at the Gumelnița site (Romania). A multi-bioarchaeological investigation (archaeobotany, zooarchaeology, anthropology) was conducted on vegetal, animal, and human remains, alongside radiocarbon dating and stable isotope analyses (δ13C, δ15N) of humans (n = 33), mammals (n = 38), reptiles (n = 3), fishes (n = 8), freshwater mussels shells (n = 18), and plants (n = 24). According to the results of δ13C and δ15N values and FRUITS, the inhabitants of Gumelnița had a diet based on crops and using natural resources, such as fish, freshwater molluscs and game. Although domestic fauna was occasionally exploited for meat, it had a role in providing secondary products. Crops were heavily manured, and chaff and other crop waste may have been necessary fodder for cattle and sheep. Dogs and pigs fed on human waste, although the diet of the latter is more similar to that of wild boars. Foxes had a diet close to dogs, which may indicate synanthropic behaviour. Radiocarbon dates were calibrated with the percentage of freshwater resources obtained by FRUITS. As a result, the corrected dates for the freshwater reservoir effect (FRE) have a delay of an average of 147 years. According to our data, this agrarian community developed a subsistence strategy under the pressure of some climatic changes that started after 4300 cal BC, corresponding to KGK VI rapid collapse/decline episode tracked recently (that begins around 4350 cal BC). This matching of our data in the two models (climatic and chrono-demographic) allowed us to capture the economic strategies that led to the resilience of those people more than other contemporary KGK VI communities.

Filtration capabilities of freshwater mussel (Lamellidens marginalis) and apple snail (Pila globosa) and their potential impacts on freshwater integrated multitrophic aquaculture systems

Aim: The study aimed to assess the relative filtration rates of an indigenous freshwater mussel, Lamellidens marginalis and an indigenous freshwater snail, Pila globosa, and their suitability for incorporation into freshwater integrated multi-trophic aquaculture (FIMTA) systems. Methodology: An indoor experimental trial was conducted in a wet laboratory (temperature: 30.5 ± 0.5, light intensity: 2000 lux, light cycle: L: D: 12hr: 12hr). The trial was performed in glass aquaria in triplicate filled with algae rich water to assess their filtration rate. Simultaneously, the impacts of these two molluscs on inorganic nitrogen and phosphorus were evaluated. Results: L. marginalis exhibited filtration rates of 934.7± 0.07 cells min-1 mussel-1 and 13.79 ± 0.04 cells g-1 min-1) against 261.8 ± 10.15 cells min-1 snail-1 and 9.74±0.15 cells g-1 min-1 for P globosa. Similarly, the mussel also exhibited markedly higher turbidity and chlorophyll clearance capacity (p<0.05) in comparison to snail, especially during initial 6-12 hr when initial concentrations of algal population, turbidity and Chl-a were high. Notably, the oxygen consumption and ammonia excretion rates were greater for snail than mussel after 24hr and at the end of the experiment. Interpretation: The results provide quantitative information on the filtration capacity of two indigenous freshwater molluscs that have considerable local food as well as economic value and would pave the way for their utilization as ecological engineers, especially organic extractive in freshwater integrated multi-trophic aquaculture (FIMTA) system. It is concluded from the study that L. marginalis was more efficient in extracting almost four times algal cells than, P. globosa. Key words: Eutrophication, Filtration, Lamellidens marginalis, Pila globosa

First record of an autochthonous community of fluviatile freshwater molluscs from the Middle/Late Miocene Upper Freshwater Molasse (southern Germany)

First record of an autochthonous community of fluviatile freshwater molluscs from the Middle/Late Miocene Upper Freshwater Molasse (southern Germany)

INVASION OF THE THIARID SNAIL Melanoides tuberculata (MOLLUSCA) IN A CONSERVATION AREA OF THE SEMIARID REGION OF BRAZIL

This paper records the invasive gastropod Melanoides tuberculata in a limnetic ecosystem located in integral protection area in the semiarid region of the state of Paraíba in northeast Brazil. Live individuals were collected and photographed along shallow margins of the Piranhas Reservoir associated with different types of substrates. Photographic quadrants were used to calculate the number of living individuals and empty shells on different substrates. Individuals of M. tuberculata were found at five sampling sites in the littoral zone on different types of substrates with densities ranging of 13 ind.(m2)-1 to 22 ind.(m2)-1. The average density of individuals was: 18 ind.(m2)-1 on thin sediment, 15 ind.(m2)-1 on gravel and 20 ind.(m2)-1 on rocks. Empty shells were extremely abundant in the terrestrial zone of the reservoir. We did not observe native species of freshwater molluscs in the marginal areas of the reservoir in which the specimens of M. tuberculata were found. Knowledge about the distribution, establishment and impact caused of M. tuberculata in limnetic ecosystems of the Brazilian semi-arid region needs to be better studied in order to ascertain the degree of impact on native species and environmental modifications that reflect negatively on ecosystems.