Brackish Water Snails Research Articles

Analyzing the Co-occurrence of Endangered Brackish-Water Snails with Other Species in Ecosystems Using Association Rule Learning and Clustering Analysis

Analyzing the Co-occurrence of Endangered Brackish-Water Snails with Other Species in Ecosystems Using Association Rule Learning and Clustering Analysis

Differences in the expression of soluble proteins in freshwater and brackish‐water ecotypes of the snail Theodoxus fluviatilis

The neritid snail Theodoxus fluviatilis has formed regional subgroups in northern Europe, where it appears in both freshwater (FW) and brackish water (BW) in coastal areas of the Baltic Sea. These ecotypes show clear differences in osmotolerance and in the modes of accumulating organic osmolytes under hyperosmotic stress. We reasoned that the expression patterns of soluble proteins in the two ecotypes may differ as well. BW snails have to deal with a higher salinity (up to 20‰) than FW snails (0.5‰) and also cope with frequent fluctuations in environmental salinity that occur after heavy rains or evaporation caused by extended periods of intense sunshine. Therefore, the protein expression patterns of specimens collected at five different FW and BW sites were analyzed using 2D SDS-PAGE, mass spectrometry, and sequence comparisons based on a transcriptome database for Theodoxus fluviatilis. We identified 89 differentially expressed proteins. The differences in the expression between FW and BW snails may be due to phenotypic plasticity, but may also be determined by local genetic adaptations. Among the differentially expressed proteins, 19 proteins seem to be of special interest as they may be involved in mediating the higher tolerance of BW animals towards environmental change compared with FW animals.

高知県初記録のウスベニツバサカノコ（腹足網：アマオブネ科）

高知県初記録のウスベニツバサカノコ（腹足網：アマオブネ科）

Checklist of the fresh and brackish water snails (Mollusca, Gastropoda) of Bénin and adjacent West African ecoregions

Currently no comprehensive checklist of fresh and brackish water gastropods from Bénin exists, and those for adjacent West African areas are outdated. Yet, such checklists provide essential biodiversity information and a consistent taxonomic and nomenclatural framework for that biodiversity. Here a first checklist of the fresh and brackish water gastropods from Bénin and adjacent West African ecoregions is presented, based on an extensive literature review and field surveys between September 2014 and June 2019 in six major fresh and brackish water ecosystems in Bénin. This inventory includes information on synonymy, species distribution in West Africa, habitats, and conservation status. The fresh and brackish water gastropod fauna includes 60 species, belonging to 28 genera and 16 families. Pachychilidae, Ampullariidae, Neritidae, and Bulinidae were the most diverse families with 9, 8, 7, and 7 species, respectively. However, literature and field data indicated that 23 species observed in West African basins that extend to Bénin do not occur in the territory of Bénin. These species were not detected in our field surveys, most likely because they are rare at collecting sites. Of the 60 species included, five are classified as “Data Deficient”, 43 as “Least Concern”, two as “Nearly Threatened”, one as “Vulnerable”, and six as “Endangered” by the IUCN, whereas the remaining three species were not evaluated. Because the taxonomy of fresh and brackish water gastropods in West Africa is still largely based on morphology, comparative molecular and taxonomic studies may result in substantial revisions of this checklist over the coming years.

Persistence of Habitats and Populations of Small, NativeTryonia(Hydrobiidae) Snails in Brackish Marshes around San Francisco Bay, California, after Severe Drought*

Around the year 2000, populations of inconspicuous, 5-mm hydrobiid snails were discovered at several semi-isolated marshes around San Francisco Bay, California, where freshwater meets salt water. Coring indicated these are native species, including Tryonia porrecta (Mighels, 1845). The present, long-term monitoring at some of these sites with and without these small snails suggested that these abundances tend to be quite stable, through present 2014 sampling. But the recent, record drought since 2012 risked high salinities in these vulnerable brackish areas, including a site with the normally rare California Brackish Water Snail, Tryonia imitator (Pilsbry, 1899). Sites in presently 100% seawater at Elkhorn Slough on nearby Monterey Bay, once with frequent T. imitator brackish water snails yielded only dead shells during this past 15 years, among large, introduced predatory snails. Yet a more isolated site nearby at 50% seawater yielded small (3 mm) T. imitator brackish water snails observed (live) on green algae among pickleweed, at warm (30 °C) water temperatures, with no other gastropod species, soon after rare rains during the drought, in April, 2014. Isolated marshes may have advantages in slowing colonization of invasive species. Despite vulnerability of semi-isolated brackish-water sites to elevated salt during drought, some sites maintained these native snails (without invasive snails) even after drought.

English

Brackish water snail is one of the important intermediate hosts of trematode infections. This kind of snail along the Gulf of Thailand were examined for cercariae, the larval stage of trematodes. The aim of this study was to investigate cercarial infections in brackish water snails in the central and eastern side of the Gulf of Thailand. Snails were collected from 45 sampling sites (20 central areas, 25 eastern areas), between August 2013 and February 2014. A total of 8,532 snails were classified into 12 families, 23 genera and 32 species. Cercarial infections were investigated using shedding and crushing methods. The infection rate was 0.27% (23/8,532). The cercariae were categorized into 5 types and 8 species. The first type, Parapleurophocercous cercariae, consisted of Haplorchis taichui, Heterophyes cercaria I, and Metorchis intermedius. The second type, Xiphidiocercariae, consisted of Ascorhytis charadriformis. The third type, Furcocercous cercariae, consisted of Apharyngostrigea pipientis. The forth type, Cotylomicrocercous cercariae, consisted of Coitocaecum anaspidis. The fifth type, Echinostome cercariae, consisted of Hypoderaeum conoideam and Himasthla interrupta. Seven species of snails were found with trematode infections, comprising of Assiminea brevicula, Cerithidea cingulata, Cerithidea alata, Cerithidea djadjariensis, Cerithidea quadrata, Littorinopsis intermedia, and Sermyla riqueti.   Key words: Cercaria, brackish water snails, trematode, the Gulf of Thailand. &nbsp

Mosaics in the mangroves: allopatric diversification of tree-climbing mudwhelks (Gastropoda: Potamididae:Cerithidea) in the Indo-West Pacific

The Indo-Australian Archipelago (IAA) is the richest area of biodiversity in the marine realm, yet the processes that generate and maintain this diversity are poorly understood and have hardly been studied in the mangrove biotope. Cerithidea is a genus of marine and brackish-water snails restricted to mangrove habitats in the Indo-West Pacific, and its species are believed to have a short pelagic larval life. Using molecular and morphological techniques, we demonstrate the existence of 15 species, reconstruct their phylogeny and plot their geographical ranges. Sister species show a pattern of narrowly allopatric ranges across the IAA, with overlap only between clades that show evidence of ecological differentiation. These allopatric mosaic distributions suggest that speciation may have been driven by isolation during low sea-level stands, during episodes preceding the Plio-Pleistocene glaciations. The Makassar Strait forms a biogeographical barrier hindering eastward dispersal, corresponding to part of Wallace's Line in the terrestrial realm. Areas of maximum diversity of mangrove plants and their associated molluscs do not coincide closely. © 2013 The Natural History Museum. Biological Journal of the Linnean Society © 2013 The Linnean Society of London, 2013, 110, 564–580.

Brackish water snails from Qi?ao Island in the Pearl River estuary, China

Eight brackish water snails belonging to 5 families are described. All the samples were taken from 3 different types of water body. They were taken from 1 littoral of an artificial brackish lake, 1 intertidal zone of a brackish tidal river, and 3 mangrove swamps on Qi'ao Island in the Pearl River estuary, Guangdong Province, southern China. Assiminea estuarina Habe, 1946 and Iravadia (Fairbankia) cochinchinensis Bavey & Dautzenberg, 1910 are new records for China. Cerithidea sinensis Philippi, 1848 was found in a tropical zone for the first time. The finding of Sphaerassiminea brevicula (Pfeiffer, 1855) provided evidence that this species can tolerate brackish or salt water. Iravadia ornata Blanford, 1867 was the most widespread species at the sampling sites. The types of water and habitat temperature mainly affected the distribution of Melanoides tuberculata (Muller, 1774).

和歌川河口域における汽水性希少巻貝ワカウラツボ個体群の変動

和歌川河口域における汽水性希少巻貝ワカウラツボ個体群の変動

Foodborne intestinal flukes in Southeast Asia.

In Southeast Asia, a total of 59 species of foodborne intestinal flukes have been known to occur in humans. The largest group is the family Heterophyidae, which constitutes 22 species belonging to 9 genera (Centrocestus, Haplorchis, Heterophyes, Heterophyopsis, Metagonimus, Procerovum, Pygidiopsis, Stellantchasmus, and Stictodora). The next is the family Echinostomatidae, which includes 20 species in 8 genera (Artyfechinostomum, Acanthoparyphium, Echinochasmus, Echinoparyphium, Echinostoma, Episthmium, Euparyphium, and Hypoderaeum). The family Plagiorchiidae follows the next containing 5 species in 1 genus (Plagiorchis). The family Lecithodendriidae includes 3 species in 2 genera (Phaneropsolus and Prosthodendrium). In 9 other families, 1 species in 1 genus each is involved; Cathaemaciidae (Cathaemacia), Fasciolidae (Fasciolopsis), Gastrodiscidae (Gastrodiscoides), Gymnophallidae (Gymnophalloides), Microphallidae (Spelotrema), Neodiplostomidae (Neodiplostomum), Paramphistomatidae (Fischoederius), Psilostomidae (Psilorchis), and Strigeidae (Cotylurus). Various types of foods are sources of human infections. They include freshwater fish, brackish water fish, fresh water snails, brackish water snails (including the oyster), amphibians, terrestrial snakes, aquatic insects, and aquatic plants. The reservoir hosts include various species of mammals or birds.The host-parasite relationships have been studied in Metagonimus yokogawai, Echinostoma hortense, Fasciolopsis buski, Neodiplostomum seoulense, and Gymnophalloides seoi; however, the pathogenicity of each parasite species and host mucosal defense mechanisms are yet poorly understood. Clinical aspects of each parasite infection need more clarification. Differential diagnosis by fecal examination is difficult because of morphological similarity of eggs. Praziquantel is effective for most intestinal fluke infections. Continued efforts to understand epidemiological significance of intestinal fluke infections, with detection of further human cases, are required.

Growth, reproduction and recruitment of the endangered brackish water snail Iravadia (Fairbankia) sakaguchii (Gastropoda : Iravadiidae)

The population structure and reproductive activity of the brackish water snail Iravadia (Fairbankia) sakaguchii, which lives under partially buried stones on intertidal mudflats, were investigated monthly in the Waka River Estuary, Wakayama, central Japan. Observations of the reproductive organs indicated the main reproductive season as being from June to July. Maturation size was estimated to be approximately 4.0 mm in shell length (SL) in females and 3.9 mm SL in males, there being no significant sexual dimorphism in adult body size. The occurrence of snails smaller than 2 mm SL indicated that recruitment occurred between August and October, all the recruits co-occurring with adults under stones. The recruits grew to a large size (>3 mm SL) and reached maturity in August of the second year (1 year old), longevity being estimated as at least 37–38 months. Throughout the study period of 28 months, the population mostly comprised individuals between 3 and 5 mm SL, with recruits being fewer than older snails. The population density decreased each year, this being attributable to a low level of recruitment.

汽水棲巻貝ワカウラツボ（腹足綱：ワカウラツボ科）の分布に関係する要因

Factors affecting the spatial distribution of the brackish water snail Iravadia (Fairbankia) sakaguchii were investigated in the field in the Waka River Estuary (34°10'N, 135°10'E) of central Japan and in the laboratory. The snails occurred under stones partially buried on intertidal muddy flats. A tracking survey of marked snails released beneath stones revealed that many of the snails moved among the stones. Observations in tide-simulating tanks indicated that most of the snails came out from beneath the stones and were active during both daytime and nighttime submergence. Salinity tolerance tests in the laboratory showed that the snails died within 6 days at 0 psu, 7 days at 5 psu, and 12 days at 10 psu, whereas no snails died during 13 days of exposure to higher salinity conditions (20-35 psu). Neither immigration nor retention rates of snails differed significantly between partially buried stones and non-buried stones artificially placed in the field. This indicates that the extent of burial of the stones is not critical for habitat selection by the snails. Preference tests conducted in the laboratory and in the field revealed that the snails prefer mud to sand under the stones. Retention and survival rates were lower for snails released with stones in the lower intertidal zone than for those released with stones in the middle intertidal zone, and this suggests the importance of tidal exposure in habitat selection of I. (F) sakaguchii.

Distribution of the Brackish Water Snail, Assiminea japonica Martens (Gastropoda : Assimineidae) along Hinuma Water System, Middle Japan, with a Comparison of Population Structure between Observation Sites

Distribution of the Brackish Water Snail, Assiminea japonica Martens (Gastropoda : Assimineidae) along Hinuma Water System, Middle Japan, with a Comparison of Population Structure between Observation Sites

Description and relationships of a new brackish-water snail genus (Gastropoda: Hydrobiidae: Littoridininae) from Hispaniola

Whole-animal anatomy is used in a cladistic analysis of five genera of brackish-water hydrobiids living in the western Atlantic. Antillobia margalefi gen. & sp. nov. (Hydrobiidae: Littoridininae) is described based on specimens from Lago Enriquillo, an inland saline lake in the Dominican Republic. The topology (Hydrobia (Spurwinkia (Heleobia (Heleobops (Antillobia))))) is considerably better than any alternative. Among 27 characters and a total of 39 character states used in the analysis, only two convergences are detected, and these involve the genitalia. Detailed anatomical data are shown to be necessary to assess relationships in the presence of constraints on morphological evolution imposed by a very small size.

Description and relationships of a new brackish-water snail genus (Gastropoda: Hydrobiidae: Littoridininae) from Hispaniola

Whole-animal anatomy is used in a cladistic analysis of five genera of brackish-water hydrobiids living in the western Atlantic. Antillobia margalefi gen. & sp. nov. (Hydrobiidae: Littoridininae) is described based on specimens from Lago Enriquillo, an inland saline lake in the Dominican Republic. The topology ( Hydrobia (Spurwinkia (Heleobia (Heleobops (Antillobia))))) is considerably better than any alternative. Among 27 characters and a total of 39 character states used in the analysis, only two convergences are detected, and these involve the genitalia. Detailed anatomical data are shown to be necessary to assess relationships in the presence of constraints on morphological evolution imposed by a very small size.

The Life Cycle of Cloacitrema michiganensis McIntosh, 1938 (Trematoda: Philophthalmidae)

Experimental infections of Cloacitrema michiganensis were established in chicks by inoculation per cloaca with excysted metacercariae. Ovigerous adults were present 20 days later with eggs containing ocellate miracidia after 21 days. The eggs hatch in utero; the miracidium contains a fully developed redia. Rediae of 2 size groups were present in the digestive gland of the brackish-water snail, Cerithidea californica. Megalurous cercariae are released and encyst on submerged objects. The stages of C. michiganensis resembled those of Parorchis acanthus, a philophthalmid also infecting C. californica, except for differences in the epidermal plate count of their miracidia and in their cercarial stage which was larger in P. acanthus and had a spinuous tegument with a collar of spines.

Two new notocotylid trematodes from birds in Tasmania and their life histories

Paramonostomum caeci n. sp., adults of which occur mainly in the intestinal caeca of Anas supereiliosa, Cygnus atratus and Polioeephalus polioeephalus, is described. It is considered to closely resemble P. malerisehi from which it differs in being only one-third the size, having a spinose tegument and a cirrus covered with tubercles. P. bursae n.sp., adults of which have been found inhabiting the bursa of Fabricius of Anas supereiliosa is described and considered to be most similar to P. alveatum and P. parvum but to differ from them in the distribution of its vitellaria, the position of its ovary relative to the testes and in having a greater number of uterine loops. The domestic duck, Anas platyrhynehos, was found to serve as an experimental host for both new species. A brackish water snail, Coxiella badgerensis, inhabiting Calverts Lagoon in southeast Tasmania serves as a natural intermediate host for P. caeci n.sp. and P. bursae n.sp. and also for two other undescribed notocotylids. Developmental stages (rediae, cercariae and metacercariae) of both new Paramonostomum species are described. The cercaria of P. caeci n. sp. belongs to the Imbricata group, and that of P. bursae n.sp. to the Yenchingensis group.

Present knowledge of the non-marine invertebrate fauna of the Outer Hebrides

SynopsisThe Outer Hebrides, because of their apparent isolation, attracted zoologists in the past who looked for new species and subspecies and some sought to explain the origin of the invertebrate fauna by exotic land connections in preglacial times. These expectations were largely unfulfilled and the speculations are unsupported by geologists or geomorphologists. The non-marine invertebrate fauna is examined from published records, museum collections and special field surveys and the lists total over 2500 species, of which approximately one-third are of general occurrence in the Outer Hebrides. Three species of mites are new to the British fauna and over 700 species, mainly insects, are additions to the Hebridean fauna. The fauna is impoverished compared with the mainland and this may be due to climate and the lack of variety of habitats and the low structure of the vegetative cover. Upland species occur on the moors and some descend to sea level, possibly on account of the low mean temperature in summer. Species with a north western distribution occur in the Odonata, Hemiptera, Lepidoptera, Hymenoptera and Diptera. Species with a discontinuous distribution are discussed and it is suggested that some reached the islands by natural means and others by human agency and there is no evidence of refugia for a glacial relict fauna. Examples are given of insects with a south western distribution arriving by sea in driftwood and five amphiatlantic species, including a freshwater sponge, which may have been brought by migrating birds, a wrack-fly, two strand-line beetles and a mite, which may have been distributed by the Gulf Stream and the North Atlantic Drift.There are no endemic species, but a few so-called subspecies of insects may be restricted to the Outer Hebrides. Changes in the fauna are traceable in a stratified Flandrian shell deposit in Harris, where two species have become extinct, and some insects have also become extinct in St Kilda during the last century. Some of the most conspicuous land snails have arrived in historic times and the most rapid coloniser has been a brackish-water snail which has spread throughout the islands since 1933.

Life Cycle of Procerovum calderoni (Africa and Garcia, 1935), Price, 1940 (Trematoda: Digenea: Heterophyidae)

The life cycle of Procerovum calderoni was demonstrated experimentally in the Philippines. In the operculate brackish water snail, Thiara riquetti, the parapleurolophocercous cercaria develops in rediae and penetrates Mollienesia latipinna which was also found naturally infected. Metacercariae encysted mostly in muscles at the base of the fin cartilages, and developed to ovigerous worms in the small intestines in 8 to 10 days, when fed to laboratory-reared kittens and a puppy.

Three new Microphallid Trematodes from Tasmanian Birds

The morphology of Atriophallophorus coxiellae n.sp., Matritrema calvertensis n.sp., and Microphallus tasmaniae n.sp. (Trematoda: Microphallidae) is described. The description of A. coxiellae is based on metacercariae found encysted in the hepatopancreas and gonads of the brackish water snail Coxiella badgerensis Johnston 1878. Adult, but sexually immature, trematodes taken from the small intestine of the dotterels Charadrius cucullatus Vieillot and Charadrius ruficapillus Temminck, which feed on Coxiella badgerensis, are considered identical with the metacercariae from the snail. The account of Maritrema calvertensis n.sp. is based on adult trematodes found in the lower intestine, caeca, and rectum of the duck, Anas castanea Eyton, and dotterels Charadrius cucullatus and C. melanops Vieillot. From a comparison of metacercariae taken from certain small cysts found in the alnphipod Austrochiltonia australis Sayce 1901, and also in the alimentary tract of the birds, it is assumed that the amphipod is an intermediate host. The description of Microphallus tasmaniae n.sp. is based on adult trematodes found in the intestine, caeca and rectum of Anas castanea and the dotterels Charadrius cucullatus, C. melanops and C. ruficapillus. Certain large cysts found in the amphipod Austrochiltonia australis, and also in the gut of the birds infected with Microphallus tasmaniae n. sp., contained metacercariae almost identical with the adult. It is therefore assumed that the amphipod is an intermediate host of M. tasmaniae n.sp. The definitive and intermediate hosts of the trematodes described were all taken at Calverts Lagoon, Tasmania.