Distribution Of Freshwater Snails Research Articles

Identification of freshwater snail species and survey of their trematode infections in Ordos, China

In order to investigate and study the species and distribution of freshwater snails in Ordos area of Inner Mongolia, as well as the trematode infection in different periods, and to provide a scientific basis for the effective prevention and control of livestock trematodiasis. In this paper, freshwater snails distributed in Ordos were widely collected for morphological identification, and PCR amplification of freshwater snails COI gene and ITS2 gene was carried out with the help of molecular biology. At the same time, microscopic examination was used to observe the trematode infection of freshwater snails in two different periods from May to July and July to September, and the molecular biology of the trematodes was identified. The results showed that the 1796 freshwater snails collected belonged to two orders, three families and four genera, i.e. Bellamya, Radix, Galba, and Gyraulus. Microscopic examination of snails showed that the infection rate of trematode larvae from July to September was significantly higher than that from May to July. The collected trematodes were identified as five species, namely Cotylurus marcogliesei, Fasciola hepatica, Fasciola gigantica, Paramphistomum cervi, and Parastrigea robusta. The combination of freshwater snail species in Ordos and the infection of trematode in snails showed that a large number of freshwater snails were infected with trematodes, especially from July to September, when there is more rain and suitable climate, which causes serious harm to local livestock.

Temperature affects predation of schistosome-competent snails by a novel invader, the marbled crayfish Procambarus virginalis.

The human burden of environmentally transmitted infectious diseases can depend strongly on ecological factors, including the presence or absence of natural enemies. The marbled crayfish (Procambarus virginalis) is a novel invasive species that can tolerate a wide range of ecological conditions and colonize diverse habitats. Marbled crayfish first appeared in Madagascar in 2005 and quickly spread across the country, overlapping with the distribution of freshwater snails that serve as the intermediate host of schistosomiasis-a parasitic disease of poverty with human prevalence ranging up to 94% in Madagascar. It has been hypothesized that the marbled crayfish may serve as a predator of schistosome-competent snails in areas where native predators cannot and yet no systematic study to date has been conducted to estimate its predation rate on snails. Here, we experimentally assessed marbled crayfish consumption of uninfected and infected schistosome-competent snails (Biomphalaria glabrata and Bulinus truncatus) across a range of temperatures, reflective of the habitat range of the marbled crayfish in Madagascar. We found that the relationship between crayfish consumption and temperature is unimodal with a peak at ~27.5°C. Per-capita consumption increased with body size and was not affected either by snail species or their infectious status. We detected a possible satiation effect, i.e., a small but significant reduction in per-capita consumption rate over the 72-hour duration of the predation experiment. Our results suggest that ecological parameters, such as temperature and crayfish weight, influence rates of consumption and, in turn, the potential impact of the marbled crayfish invasion on snail host populations.

Seasonal Abundance and Distribution of Freshwater Snails in Different Beels of Gopalganj District, Bangladesh

In Bangladesh, there are thousands of beels (a natural deep depression) exist in different sizes. Most of these large beels have become shrunken quite considerably in recent decades. Those beels are the potential source of snails. Gopalganj district of Bangladesh has lots of beels from where people collect huge amount of Mollusca species from the time immemorial. At present, the abundance is decreasing drastically due to uncontrolled catch. The seasonal abundance and distribution of Mollusca species in selected beel areas has been studied to know the real scenario. Surveys was conducted at summer (May-June), rain (September-October) and winter (December-January) season year round based on the observations and sampling in each six points (each of 16m2 area per point) of a beel, As such six selected beels in each Upazila of Gopalganj district have been considered under study. Sampling was done with the help of Sieves (0.2 mm, 2.0 mm and 4.75 mm), Cast nets, small hand nets and hand-picking methods and count. In this study, five snail species were found throughout the survey period where Lomba shamuk (Lymnaea stagnalis) was exhibited the highest in number than others. The highest average number (600 no/16m2) of snail was found in Gopalganj sadar Upazila at rainy season and the species comprised of only lomba shamuk. In case of Chakti shamuk (Macrochlamys indica), the highest average number (519 no/16m2) was also found in Gopalganj sadar upazila at the same period. The abundance of average number of Ghecho shamuk (Lymnaea luteola) was found low for all studied Upazila and this species was totally absent in Muksudpur. These findings may help the concern authority to take proper decisions on meaningful steps. Ultimately these findings may help the nature from the extinction of Mollusca species.

Morphological Identification and Distribution of Freshwater Snails (Gastropods: Mollusca) in Greater Zab River, Kurdistan Region, Iraq

Morphological Identification and Distribution of Freshwater Snails (Gastropods: Mollusca) in Greater Zab River, Kurdistan Region, Iraq

Assessment of schistosomiasis transmission in the River Nile at Greater Cairo using malacological surveys and cercariometry.

Continuous field studies on the abundance and distribution of freshwater snails and cercarial populations are important for schistosomiasis control programs. In the present work, snail surveys and cercariometry were conducted for four successive seasons at 12 sites on the Nile River banks in the area of Greater Cairo to identify potential transmission foci for schistosomiasis. In addition, water physicochemical parameters were recorded. The results showed that the electrical conductivity, total dissolved solids, dissolved oxygen, and pH were within the permissible levels, except that the water temperature increased, especially in the spring season. Malacological surveys identified 10 native snail species at the studied sites of the Nile River, namelyBulinus truncatus, Biomphalaria alexandrina, Lymnaea natalensis, Lanistes carinatus, Cleopatra bulimoides, Melanoides tuberculata, Helisoma duryi, Bellamya unicolor, Physa acuta, Thedoxus niloticus,andone invasive snail species,Thiara scabra. The calculated diversity index indicated that the structure of snails' habitats was poor, while Evenness index indicated that the individuals were not distributed equally. Natural infection results identified no schistosome cercariae inB. truncatusandB. alexandrina. However, the cercariometry recoveredSchistosomacercariae in all the surveyed sites during all seasons with variable distribution. The preceding data suggest that there are still some active transmission foci for schistosomiasis infection in the Nile River. Moreover, the present finding highlights the importance of cercariomety as a complementary approach to snail samplings for identifying the transmission foci for schistosomiasis.

Physicochemical Changes and Abundance of Freshwater Snails in Anambra River (Nigeria) During the Rainy Season

Abstract Rapid diversification is a way of responding to environmental change for freshwater organisms. This work examined the physicochemical changes and abundance of freshwater snails in Anambra River (Nigeria) during the rainy season. Field studies were conducted fortnightly from June to August 2019 at three stations of the river namely: Otuocha (station I), Otunsugbe (station II), and Ukwubili (station III) about 8.35 kilometers apart from each other. A scoop net of 2 cm mesh size and handpicking was used to sample freshwater snails randomly and water samples were taken to the laboratory for physicochemical analysis. A total of 896 freshwater snails belonging to 6 species (Afropomus balanoidea, Pomacea maculata, Lymnea stagnalis, Lanistes ovum, Pila wernei, and Saulea vitrea) were collected. Pomacea maculata was the most dominant species with a relative abundance of 45.87 %, while Saulea vitrea was the least dominant species with a relative abundance of 2.34 %. There was a significant negative correlation between dissolved oxygen and Pomacea maculate (r = –0.877, p = 0.002) and a positive correlation between dissolved oxygen and Stagnalis lymnea (r = 0.840, p = 0.005). The diversity of species was highest at Otuocha (1.171) followed by Ukwubili (1.133) and Otunsugbe (0.856) with average mean temperatures of (23.1 ±0.1) °C, (27.30 ±0.00) °C, and (26.80 ±0.03) °C respectively. The distribution of freshwater snails was influenced by the physicochemical variability of Anambra River during the rainy season. Therefore, further studies for a longer time and different seasons to examine the impact of physicochemical changes on the snail distribution are encouraged.

Distribution and abundance of freshwater snails in Warwade Dam, Dutse, Northern Nigeria

Preliminary investigation in August, 2017 reported the presence of Lymnaea natalensis, Bellamya unicolor, Melanoides tuberculata and Bulinus globosus in order of increasing abundance and distribution in Warwade dam, Dutse, Jigawa State, Nigeria. A follow up study was carried out from April to October, 2019 to reveal further details on the abundance and distribution of freshwater snails in relation to some physiochemical factors of the dam. Four sampling sites; human activity, vegetation cover, lentic and lotic were selected for the study along the bank of the dam. Freshwater snails were collected using long handled scoop net with mesh 0.2mm complemented by hand picking methods in the four sampling sites. Water samples from the sampling sites were analyzed in the laboratory using standard procedures. A total of 2,027 of freshwater snails belonging to ten species were identified. Bulinus globosus 12(0.6%) and Lymnaea natalensis 12(0.6%) had the lowest abundance and distribution while Melanoides tuberculata 1553(76.6%) had the highest. Snail abundance was highest in site characterized by human activities (670) followed by vegetation (482), lotic (442) and lentic (433) waters. Most of the physico-chemical factors measured appeared to favour the growth and survival of fresh water snails. pH (p = 0.01), water current (p = <0.01) and magnesium ion concentration (p = < 0.01) varied significantly across the four sites. Only calcium ion concentration was significantly associated with snail abundance (p = 0.04). Snail abundance showed weak positive relationship with water temperature, color, turbidity and concentration of magnesium ion. The dam habours about ten species of freshwater snails in different abundance and distribution with M. tuberculata being the most abundant throughout the period of investigation. The dominance of M. tuberculata over other species particularly those of medical and veterinary importance could have positive implication for their control in the dam.

Relationship between Physico-Chemical Parameters and the Population Distribution of Fresh Water Snails in Amassoma Community and Niger Delta University Campuses, Bayelsa State, Nigeria

Evaluating the presence of fresh water snails in a location is germane in establishing a snail-borne disease control program. The purpose of the study was to see how physicochemical parameters influenced the population distribution of four fresh water snails (Lymnaea natalensis, Bulinus globosus, Biomphalaria pfeiffer, and Melanoides spp.) in the Amassoma community and Niger Delta University between March, 2021 and May 2021. Snails were gathered by plucking and scooping them by hand. Snail was identified using standard pictorial keys. Physicochemical of the water of the snail habitat were measured using standard in-situ apparatus across eight sites. Physico chemical measured were temperature, pH, conductivity, BOD, turbidity, salinity, and alkalinity. A total of 258 snails were gathered from the eight (8) different sites. In all sites, Lymnaea natalensis was more abundant. Bulinus globosus, Biomphalaria pfeiffer, and Melanoides spp. were among the other snails discovered. Lymnaea had negative correlation with pH, conductivity, BOD, and alkalinity and a positive correlation with salinity and temperature. Bulinus had a positive relationship with pH, salinity, and conductivity and a negative correlation with temperature, turbidity, BOD, and alkalinity. Biomphalaria had a positive correlation with temperature, pH, salinity, turbidity, and alkalinity Melanoides had positive correlations with Temperature, pH, salinity, BOD, and alkalinity and a negative correlation with turbidity and concentration. The was correlation between snails and snails. The presence of these snails suggests that the Amassoma village and Niger Delta University campuses are potential hotspots for a variety of snail-borne diseases.

Predicting the habitat suitability of Schistosoma intermediate host Bulinus truncatus, its predatory aquatic insect Odonata nymph, and the associated aquatic plant Ceratophyllum demersum using MaxEnt.

Schistosomiasis is one of the most important parasitic diseases in tropical and subtropical areas. Its prevalence is associated with the distribution of freshwater snails, which are their intermediate hosts. Thus, control of freshwater snails is the solution to reduce the transmission of this disease. This will be achieved by understanding the relationship between the snails and their habitats including natural enemies and associated aquatic plants as well as the factors affecting their distribution. In this study, Maximum Entropy model (MaxEnt) was used for mapping and predicting the possible geographic distribution of Bulinus truncatus snail (the intermediate host of Schistosoma haematobium), Odonata nymph (predatory aquatic insect), and Ceratophyllum demersum (the associated aquatic plant) in Egypt based on topographic and climatic factors. The models of the investigated species were evaluated using the area under receiver operating characteristic curve. The results showed that the potential risk areas were along the banks of the Nile River and its irrigation canals. In addition, the MaxEnt models revealed some similarities in the distribution pattern of the vector, the predator, and the aquatic plant. It is obvious that the predictive distribution range of B. truncatus was affected by altitude, precipitation seasonality, isothermality, and mean temperature of warmest quarter. The presence of B. truncatus decreases with the increase of altitude and precipitation seasonality values. It could be concluded that the MaxEnt model could help introducing a predictive risk map for Schistosoma haematobium prevalence and performing better management strategies for schistosomiasis.

The effect of physico chemical parameter on the distribution of fresh water snails in the Federal Capital Territory, Abuja, Nigeria

Some species of freshwater snails are known to be intermediate hosts of biomedical importance. This study was conducted to identify some physico-chemical parameters of water bodies associated with the distribution of freshwater snail species in the Federal Capital Territory, Abuja. Eight water bodies in four locations were surveyed for the presence of freshwater snails. Five physico chemical parameters (pH, temperature, dissolved oxygen content, salinity and water speed) were measured using standard water meters. A correlation matrix between the water parameters and the snail species were analysed. A total of 1,225 freshwater snails belonging to eight species and families were collected in the study area. These were Bulinus truncatus 304 (24.8%), B. umbilicatus 162 (13.2%), B. globosus 138 (11.3%), Biomphalaria pfeifferi 138 (11.3%), Aplexa waterloti 190 (15.5%), Physa acuta 96 (7.8%), Lymnea natalensis (15.8%). and Melanoides tuberculata 3 (0.2%). Three of these snail species {B. globosus, B. Pfeffeiri and L. natalensis} which are known intermediate hosts of schistosomes were reasonably present in the study area. Out of the five water parameters investigated, two (Dissolved oxygen content and salinity) were found to significantly associated with the distribution of freshwater snail species in the area (P<0.05). The study recommends freshwater snail control intervention to interrupt the transmission and spread of human and animal diseases in the area.

KEANEKARAGAMAN DAN KOMPOSISI KEONG AIR TAWAR (MOLLUSCA: GASTROPODA) DI BEBERAPA SITU KABUPATEN BOGOR DAN KABUPATEN SUKABUMI

Many small lakes in Bogor and surrounding areas continue to shrink by silting and land conversion that will affect the diversity of aquatic fauna species, including freshwater snails. Research on the diversity and distribution of freshwater snails was conducted in Bogor Regency (Situ Cilalay, Situ Ciriung, Situ Kabantenan) and Sukabumi (Situ Gunung) in September-November 2017. This study identified freshwater snail species, analyzed the similarity of species composition and distribution, and analyzed the influencing environmental factors. Snail sampling from each lake was carried out at three stations using 5 x 1 m2 plots. A total of 936 individual specimens from 12 stations have been collected and identified, consisting of 7 families and 12 species of freshwater snails. Filopaludina javanica dominates the population in Situ Cilalay, Situ Ciriung, and Situ Kabantenan with the presence of 417 individuals (44.5%), while Melanoides tuberculata is the most widely distributed species found in 11 of 12 stations. The presence of two species, Clea sp. found in Situ Cilalay and Polypylis kennardi found in Situ Ciriung and Situ Kabantenan, has not been reported previously.

Population Dynamics, Diversity and Distribution of Freshwater Snails in Zobe Dam, Dutsin-Ma, North-Western Nigeria

Freshwater snails are crucial in assessing the ecological status of water bodies beside their economic, public and veterinary health importance. Hence, ecological studies pertaining to their abundance, diversity and distribution become paramount. A total of 1664 freshwater snails were sampled in Zobe Dam and the physicochemical parameters of the water body were analyzed on a monthly basis from April to September 2017 following standard protocols. Among the 1664 snails collected, 788 (47.94%) were Lymnaea natalensis, 492 (29.93%) were Bulinus trophicus and 364 (26.14%) were Bulinus forskalii. The study revealed monthly and spatial variation in the population of snails. Diversity and distribution of snails in Zobe Dam was influenced by pH, dissolved oxygen, conductivity and turbidity. Coefficient of correlation (r) between snail species and the physicochemical parameters of water such as dissolved oxygen, turbidity and conductivity had a strong positive correlation with all the three species while pH was found to have a weak positive correlation with only Lymnaea natalensis. In conclusion, Lymnaea natalensis was the most abundant in population of snails inhabiting Zobe Dam and the population of snail varied with the physicochemical parameters of the water body.

세종 · 대전시 일부 지역의 담수패류 분포와 유미유충 감염실태 조사

세종 · 대전시 일부 지역의 담수패류 분포와 유미유충 감염실태 조사

The influence of industrial environment on the distribution of freshwater snails in Uppersilesian Industrial Region

The influence of industrial environment on the distribution of freshwater snails in Uppersilesian Industrial Region

Identification of Medically Important Snails of Miangran Lake in Izeh, Khuzestan Province of Iran

Background: Some freshwater snails are acting as intermediate hosts for digenetic trematodes. Studies on distribution of freshwater snails are important to determine the transmission patterns of the trematoda. Objectives: The current study aimed to identify medically important snails of Miangran Lake in Izeh, Khuzestan province, Iran. Materials and Methods: Sampling was conducted in fourteen sites around Miangran Lake in 2014. The collected samples were placed in plastic containers containing 70% ethyl alcohol, prior to consideration. The identification was carried out according to shell characteristics. Data were analyzed descriptively. Results: All sampling sites were positive for medically important snails. Overall, nine genera and thirteen species were identified. The most diversity in genus was found in Melanopsis. Five genera of snails detected in the study with known medical importance include: Bithynia spp., Bulinus spp., Lymnaea spp., Melanoides spp. and Melanopsis spp. Melanoides spp. was observed in thirteen and Bellamya spp. was identified in two sites. Also, in this study Melanoides spp., Bulinus spp., and Lymnaea spp. were widespread snails around Miangran Lake. Conclusions: The reason for difference in the detected snail genera in sampling sites may be due to various physicochemical factors. According to the current study, medically important snails exist in Miangran Lake and they could be a source of trematode infections for the local people. Controlling measures after comprehensive studies should be applied.

Modelling climate change impact on the spatial distribution of fresh water snails hosting trematodes in Zimbabwe.

BackgroundFreshwater snails are intermediate hosts for a number of trematodes of which some are of medical and veterinary importance. The trematodes rely on specific species of snails to complete their life cycle; hence the ecology of the snails is a key element in transmission of the parasites. More than 200 million people are infected with schistosomes of which 95% live in sub-Saharan Africa and many more are living in areas where transmission is on-going. Human infection with the Fasciola parasite, usually considered more of veterinary concern, has recently been recognised as a human health problem. Many countries have implemented health programmes to reduce morbidity and prevalence of schistosomiasis, and control programmes to mitigate food-borne fascioliasis. As these programmes are resource demanding, baseline information on disease prevalence and distribution becomes of great importance. Such information can be made available and put into practice through maps depicting spatial distribution of the intermediate snail hosts.MethodsA biology driven model for the freshwater snails Bulinus globosus, Biomphalaria pfeifferi and Lymnaea natalensis was used to make predictions of snail habitat suitability by including potential underlying environmental and climatic drivers. The snail observation data originated from a nationwide survey in Zimbabwe and the prediction model was parameterised with a high resolution Regional Climate Model. Georeferenced prevalence data on urinary and intestinal schistosomiasis and fascioliasis was used to calibrate the snail habitat suitability predictions to produce binary maps of snail presence and absence.ResultsPredicted snail habitat suitability across Zimbabwe, as well as the spatial distribution of snails, is reported for three time slices representative for present (1980-1999) and future climate (2046-2065 and 2080-2099).ConclusionsIt is shown from the current study that snail habitat suitability is highly variable in Zimbabwe, with distinct high- and low- suitability areas and that temperature may be the main driving factor. It is concluded that future climate change in Zimbabwe may cause a reduced spatial distribution of suitable habitat of host snails with a probable exception of Bi. pfeifferi, the intermediate host for intestinal schistosomiasis that may increase around 2055 before declining towards 2100.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-014-0536-0) contains supplementary material, which is available to authorized users.

Modelling climate change impact on the spatial distribution of fresh water snails hosting trematodes in Zimbabwe

Freshwater snails are intermediate hosts for a number of trematodes of which some are of medical and veterinary importance. The trematodes rely on specific species of snails to complete their life cycle; hence the ecology of the snails is a key element in transmission of the parasites. More than 200 million people are infected with schistosomes of which 95% live in sub-Saharan Africa and many more are living in areas where transmission is on-going. Human infection with the Fasciola parasite, usually considered more of veterinary concern, has recently been recognised as a human health problem. Many countries have implemented health programmes to reduce morbidity and prevalence of schistosomiasis, and control programmes to mitigate food-borne fascioliasis. As these programmes are resource demanding, baseline information on disease prevalence and distribution becomes of great importance. Such information can be made available and put into practice through maps depicting spatial distribution of the intermediate snail hosts. A biology driven model for the freshwater snails Bulinus globosus, Biomphalaria pfeifferi and Lymnaea natalensis was used to make predictions of snail habitat suitability by including potential underlying environmental and climatic drivers. The snail observation data originated from a nationwide survey in Zimbabwe and the prediction model was parameterised with a high resolution Regional Climate Model. Georeferenced prevalence data on urinary and intestinal schistosomiasis and fascioliasis was used to calibrate the snail habitat suitability predictions to produce binary maps of snail presence and absence. Predicted snail habitat suitability across Zimbabwe, as well as the spatial distribution of snails, is reported for three time slices representative for present (1980-1999) and future climate (2046-2065 and 2080-2099). It is shown from the current study that snail habitat suitability is highly variable in Zimbabwe, with distinct high- and low- suitability areas and that temperature may be the main driving factor. It is concluded that future climate change in Zimbabwe may cause a reduced spatial distribution of suitable habitat of host snails with a probable exception of Bi. pfeifferi, the intermediate host for intestinal schistosomiasis that may increase around 2055 before declining towards 2100.

The occurrence and distribution of freshwater snails in a heavily industrialised region of Poland (Upper Silesia)

Anthropogenic water bodies namely fish ponds, clay pits, sand pits, dam reservoirs or mining subsidence pools are the characteristic feature of Upper Silesian landscape. In the study, the gastropod communities occurring in 296 anthropogenic water bodies were discussed in relation to their distribution in macroregions of Upper Silesia, role in industrialised and urbanised environment and the significance for regional biodiversity. In period 1998–2002, 31 freshwater gastropod species were found in the study area. It is noteworthy, that the anthropogenic water habitats of Upper Silesia provide a refuge for several rare and vulnerable species, among them e.g. Anisus leucostoma (Millet, 1813), Gyraulus rossmaessleri (V. Auerswald, 1852) and Hippeutis complanatus (Linnaeus, 1758).

Distribution and habitats of Gyraulus costulatus, potential snail intermediate host of intestinal flukes of the family Echinostomatidae in South Africa

This paper focuses on the geographical distribution and habitats of Gyraulus costulatus as reflected by the 736 localities currently on record in the database of the National Freshwater Snail Collection (NFSC) of South Africa. Although a wide variety of water body types was reported for this species, the largest number of samples were yielded by rivers, streams and dams which were described as perennial with predominantly fresh and clear water. A mainly stony substrate and the presence of aquatic vegetation were recorded for the majority of localities at the time of survey. An integrated decision tree constructed from the data indicated that altitude, temperature and water bodies were the most important of the factors investigated that determined the documented geographical distribution of this species in South Africa. This was supported by the effect size values calculated separately for each factor. Since the early eighties of the previous century, surveys to monitor and update the geographical distribution of freshwater snails and snail-borne parasitic diseases have been relegated to a low priority issue and this is a matter of concern. It is recommended that the exact role of G. costulatus in the epidemiology of economically important helminth parasites in South Africa should be investigated.

Distribution of freshwater snails in the man-made Oyan Reservoir, Ogun State, Nigeria

The factors influencing patterns of snail distribution in Oyan Reservoir, a typically medium sized man-made reservoir in southwest Nigeria, were investigated once a month, for 28 months (August 1990-November 1992). During each monthly visit, seven stations were sampled for relative snail density, vegetation cover and physical and chemical properties of the lake water. Statistical analyses were performed to determine the influence of these factors on snail abundance and distribution. Seven aquatic snail species were found in the reservoir, namely Bulinus globosus, B. forskalii, B. truncatus, Lymnaea natalensis, Indoplanorbis exustus, Potadoma freethi and Potadoma moerchi. The relative proportion of these species was 17.6% (B. globosus), 16.1% (B. forskalii), 0.2% (B. truncatus), 12.9% (L. natalensis), 23.4% (I. exustus) and 29.8% (both Potadoma spp. combined) of 28 183 snails collected over the study period. The seasonal trends of the species were variable but basically bimodal with peaks in August (rainy season) and November/December (early dry season). These trends were similar to the water level and rainfall patterns, suggesting that seasonal changes in snail density were probably influenced by these factors. Spatial distribution of each snail species was similar along each shoreline but significantly different across the E-W transect. Similar trends occurred for conductivity, dissolved oxygen and biochemical oxygen demand suggesting that these factors may have affected snail distribution across shorelines. Ten species of aquatic vegetation were identified, six of which correlated positively and significantly with various snail species. The most important of the associating vegetation was Impatiens irvingii which correlated with all snail species and served as an indicator plant for Indoplanorbis exustus, an introduced snail species in Nigeria.