Gastropod Species Research Articles

Species richness patterns and community structure of land snail communities along an urban-rural gradient in river floodplains

Urbanisation is widely considered as having a large impact on most native species. However, the species response to urbanisation varies among taxonomic groups, and its generalisation might lead to contradictory or incorrect management decisions in urban planning. Land snails, as an understudied group in this sense, are good subjects to study the impact of urbanisation due to their low dispersal capabilities and mobility. The study aimed to determine how land snail diversity patterns and community structure are influenced by urbanisation through an urban-to-rural gradient. A total of 59 terrestrial gastropod species and more than 4600 individuals were recorded at 24 alluvial sites distributed along an urban-to-rural gradient in three Slovak cities (Bratislava, Zvolen and Prešov). Most species belonged to euryecious, hygrophilous and forest specialist ecological groups; seven species were non-native to Slovakia. The results clearly highlight the negative effect of densely built areas on land snail community structure, since the proportion of indigenous and specialist species decreased progressively towards urban sites. The highest mean number of species was found in suburban zones and the lowest in urban zones, suggesting that most species favour intermediate levels of urbanisation. Some species (e.g. Arion vulgaris) were evenly distributed along the urbanisation gradient, supporting the importance of river floodplains as bio-corridors for the dispersal of gastropods.

Biodiversity dynamics of terrestrial gastropods in the tropical montane rainforests of Nuwara Eliya, Sri Lanka

Sri Lanka is home to 253 terrestrial gastropod species, most of which are endemic. However, limited research has explored the diversity, distribution, and influencing variables of these gastropods. This study sampled gastropods in tropical montane rainforests by establishing 10-50 1m2 sampling plots across 60 randomly selected sites. Among the 46 recorded species, 79% were native, and 17% were exotic. Representative species of the five endemic genera to the island and two endemic semi-slug species were recorded from these forests. Native gastropod species were primarily found in forest interiors, while exotic species inhabited forest buffer regions. The distribution of most native species is influenced by elevation, air temperature, relative humidity, rainfall, and soil pH, while elevation and rainfall play a significant role in the distribution of most exotics. Exotics display broader environmental tolerance compared to natives, enabling exotics to invade the forests. The restricted habitat of many native species within deep canopy forests makes them highly vulnerable to habitat change, whereas exotics thrive under altered conditions.

Prediction of the Breeding and Wintering Ranges of Pomacea canaliculata in China Using Ensemble Models

Pomacea canaliculata is a pest species of freshwater neotropical gastropod that has colonized the coastal regions of southern China since the 1980s and has expanded its range into temperate regions of the Yangtze River Basin. The breeding and overwintering populations of P. canaliculata have increased during its gradual northward expansion over the past 40 years. There is a high likelihood that P. canaliculata can overwinter in areas conducive to breeding due to the impacts of a changing climate. Yet, the potential future changes in the range of P. canaliculata and associated climatic determinants remain unclear. This study examined the relationship between the limits of geographic distribution and key climate variables determining suitability for P. canaliculata breeding and wintering periods using the ensemble species distribution models from the R package BIOMOD2. Future climate suitability and changes were assessed under two representative concentration pathways (RCP 4.5 and RCP 8.5). The predictions indicated that P. canaliculata is most sensitive to monthly minimum temperature and that this species will extend its breeding range towards northern latitudes and will establish increased wintering locations in China. The predictions for both breeding and overwintering populations suggest a northward shift in the most suitable habitat, a reduction of highly suitable areas in the south, and an increase in suitable areas along the center and east of the Yangtze River Basin extending further northwards. Within the context of an overall expansion in P. canaliculata and climate warming, there should be a focus on the center of the Yangtze River Basin in which this species can overwinter for breeding only. Early monitoring and proactive measures to effectively prevent further spread of this species should be prioritized in this region characterized by abundant rice cultivation and fish breeding.

Uso de ferramenta geoespacial para predição da distribuição de Melanoides tuberculata (Müller, 1774) e alguns gastrópodes límnicos nativos encontrados no Brasil

Abstract: One of the most common environmental impacts that has caused irreversible effects on ecosystems is the introduction of exotic species. In addition to the ecological disasters that can be caused, such as the decline and extinction of native species, this phenomenon can generate significant economic losses and the possibility of the spread of parasites that are transmitted by these exotic species. These processes can be accentuated by climate change, which over time alters the global distribution pattern of the affected species, generating cases of niche overlap with species that share similar niches. In this sense, the knowledge about the areas with possible occurrence these species can direct the monitoring and control measures. In this study, we developed current and future prediction models to identify areas of suitability in the Neotropics for Melanoides tuberculata (Müller, 1774) and nine species of mollusks native to the American continent using the ecological niche modeling tool. In addition, we evaluated the ecological niche overlap between the invasive species and the native species of freshwater mollusks to verify whether the effects of climate change would alter the distribution of these organisms. The following methodological procedures were adopted to prepare the forecasting models: records of occurrence of the mollusks in different databases and search of environmental data for climate conditions in current and future scenarios in WorldClim 2.0 (SSP2-4.5 and SSP2-8.5). Besides, modeling procedures using seven packages of R software, evaluation of the models using the true skill statistic (TSS) metric, construction of maps and quantification and overlapping of ecological niche of the species included in the analysis. The results indicated that several areas of the Neotropics are suitable for the occurrence of M. tuberculata in the current scenarios. Moreover, the suitable areas for its occurrence will probably be expanded in both future scenarios. For native species, there were significant differences in relation to the areas of suitability, with a reduction for some species. Niche similarity tests indicated significant overlap only between M. tuberculata and the planorbid Biomphalaria straminea (Dunker, 1848). We discuss that the expansion of M. tuberculata can have negative consequences, including the reduction of native gastropod species and the spread of trematodes of medical and veterinary importance that this mollusk can transmit.

Gastrópodes potenciais hospedeiros intermediários de parasitos na região do Parque Nacional dos Lençóis Maranhenses/Brasil, um destino turístico internacional

Abstract Several aquatic ecosystems present favorable conditions for the establishment of freshwater gastropod populations in Maranhão (Brazil). However, research on these snails in this Brazilian state is more focused on Baixada Maranhense, an endemic area for schistosomiasis in Maranhão. Considering the need to expand information on the occurrence of limnic gastropods in Maranhão, a qualitative study was carried out in the Microregion of Lençóis Maranhenses. The capture of freshwater snails was carried out between June 2016 and November 2019. Were obtained 3,244 specimens of freshwater gastropods: 2,372 specimens of Biomphalaria straminea (Dunker, 1848); 17 specimens of Biomphalaria schrammi (Crosse, 1864); 19 specimens of Drepanotrema lucidum (Pfeiffer, 1939); 115 specimens of (Hydrobiidae; Rissooidea); 24 specimens of Physa marmorata Guilding, 1828; 73 specimens of Pomacea maculata (Perry, 1810); 613 specimens of Pomacea sp. (Perry, 1810). Were also found 11 shells of Biomphalaria glabrata (Say, 1818). The greatest richness of snails was observed in Tutóia. The most abundant species during the study was B. straminea (73,45%). Pomacea sp. was the most representative species with constant frequency (57,15%) in the Lençóis Maranhenses Microregion, present in lentic and lotic ecosystems. The forecast maps indicate the possibility of occurrence and establishment of freshwater gastropods species throughout the investigated region. The presence of gastropods that are hosts of parasites represents a risk to human health, especially in the Lençóis Maranhenses area, which is one of Brazil's tourist destinations. Studies on the occurrence and distribution of limnic gastropods are of great relevance for understanding the conservation status of existing species. Furthermore, they are necessary to monitor snails that act as parasite hosts.

Public parks in the city of Rio de Janeiro, southeast Brazil, and the risk of parasitosis transmission by freshwater gastropods.

Urban parks are not only important for the wellbeing of the human population, but are also widely considered to be potentially important sites for the conservation of biodiversity. However, they may offer risk parasitic infections, such as schistosomiasis and fascioliasis, which are both transmitted by freshwater snails. The present study investigated the occurrence of freshwater gastropods in urban parks of the Brazilian city of Rio de Janeiro, and their possible infection by helminths of medical-veterinary importance. Gastropods were collected from six parks (2021 - 2022) and examined for the presence of larval helminths. In all, 12 gastropod species from different families were collected: Ampullariidae, Assimineidae, Burnupidae, Lymnaeidae, Physidae, Planorbidae, Succineidae, and Thiaridae. The parasitological examination revealed cercaria of three types in five snail species, with the Pleurolophocerca cercariae type in Melanoides tuberculata (the most abundant species), Echinostoma cercariae in Physella acuta and Pomacea maculata, and Virgulate cercariae, in Pomacea sp. and Pomacea maculata. None of the Biomphalaria tenagophila and Pseudosuccinea columella (the most frequent species) specimens were parasitized by Schistosoma mansoni or Fasciola hepatica, respectively. Even so, some parks may represent a considerable potential risk for transmission of both Schistosoma mansoni and Fasciola hepatica, given the presence of these gastropod vectors and the frequent contact of visitors with the waterbodies.

Identifikasi Jenis Gastropoda Conus spp. di Perairan Pesisir Manokwari

Gastropods Conus spp. is a macrozoobenthic organism that is abundant in coastal waters and is consumed by coastal communities. Conus is a carnivorous organism that lives permanently at the bottom of the waters and has the property of accumulating pollutant materials such as pesticides, carbonates and heavy metals into the body's tissues through the food chain. The aim of this study was to identify the gastropods species Conus spp. from the Manokwari Coastal Waters. The available research method is quantitative descriptive research. The target species in this study were gastropods of the genus Conus spp. collected from the Manokwari Coastal Waters. A total of 27 individuals from 6 species of Conus spp. collected from 3 observation stations. Gastropods Conus spp. 6 species were found, namely: 1) Conus leopardus; 2) Conus imperialis; 3) Conus eburneus; 4) Conus virgo; 5) Conus planorbis, and 6) Conus lividus. The air quality parameters measured were within the appropriate range for the Gastropods Conus spp.

A Structural Analysis of Host-Parasite Interactions in Achatina fulica (Giant African Snail) Infected with Angiostrongylus cantonensis.

Angiostrongylus cantonensis is a nematode parasite that resides in the pulmonary arteries of rodents, serving as its definitive hosts. The life cycle involves several species of non-marine gastropods as intermediate hosts, and the African giant snail Achatina fulica is considered one of the most important around the world. Experimental data concerning A. cantonensis infection in the African giant snail remains notably limited. This helminth causes eosinophilic meningitis or meningoencephalitis in humans, representing an emergent zoonosis in Brazil. Understanding the host-parasite relationship through the application of new tools is crucial, given the complex interaction between zoonosis and the intricate mechanisms involving wild/human hosts, parasite adaptation, and dispersion. The objective of this study was to employ SEM as a novel methodology to understand the structural organization of the host tissue, particularly the granuloma formation. This sheds light on the complex balance between A. fulica and A. cantonensis. Nine three-month-old snails were randomly selected and exposed for 24 h to a concentration of 2000 L1/dose of A. cantonensis. A necropsy was performed 37 days after the infection, and the samples were examined using light and scanning electron microscopy (SEM). The histopathological results revealed third-stage larvae of A. cantonensis associated with granulomas distributed throughout the head-foot mass, mantle, and kidney. Scanning electron microscopy of the histological section surface showed that the granuloma is surrounded by a cluster of spherical particles, which are distributed in the region bordering the larvae. This reveal details of the nematode structure, demonstrating how this methodology can enhance our understanding of the role of granulomas in molluscan tissue. The structural characteristics of granuloma formation in A. fulica suggest it as an excellent invertebrate host for A. cantonensis. This relationship appears to provide protection to the parasite against the host's immune defense system while isolating the snail's tissue from potential exposure to nematode antigens.

Gastropod Species Diversity in The Mangrove Bale Area of Poton Bako East Lombok

Gastropoda is a class with the biggest number of species, since a class of Mollusca phylum is generally effectively adjusted to different sorts of marine and freshwater territories to earthbound conditions. So a study was conducted on the diversity of Gastropoda species in the Bale Mangrove Poton Bako East Lombok area with the aim of knowing the types of gastropods that exist in the area. The method used in this study is the quadrat transect method. The results of research on the diversity of gastropod species in the Bale Mangrove Poton Bako East Lombok area found 6 species of Gastropoda including Cerithidea sp, Telebralia sulcata, Nerita undata, Telescopium telescopium, Chicoreus capucinus, Indothais gradate. The average diversity index value of the three stations is H′ = 1.41262991 which means that the diversity of Gastropods in the Bale Mangrove Poton Bako Area of East Lombok is moderate diversity.

Distribution of Commercially Important Edible Mollusc (Bivalvia and Gastropoda) from Six Districts of Terengganu, Malaysia

Terengganu has a large coastal and wetland area where it provides habitat for edible mollusc. The edible molluscs are one of the most important sources of animal protein for the local communities. The distribution of edible molluscs was studied in six districts of the Terengganu coastal waters between August 2020 and March 2022. In each district, samples were purchased from the wet market, fishing villages and roadside outlets every four months interval. A total of 1,043 individuals was observed and 23 species of edible molluscs were recorded from six districts of Terengganu representing 11 families. Bivalves were found to be dominated by 14 species from seven families. The family Cyrenidae (bivalve) was widespread in five districts where Geloina expansa, was recorded in almost all districts. Meanwhile, for gastropods, nine species from four families were found where Ellobiidae (gastropod) was dominant and the most common gastropod species was Faunus ater, which was found in four locations in Terengganu. These species have great commercial value in Terengganu districts as they are sought extensively as food by the locals and also represent one of their sources of financial survival, especially for those living near to coastal areas. This baseline study could serve as a future indicator for the sustainable management of fisheries resources and for further ecological studies.

Comparative genomic analysis of chemosensory-related gene families in gastropods

Chemoreception is critical for the survival and reproduction of animals. Except for a reduced group of insects and chelicerates, the molecular identity of chemosensory proteins is poorly understood in invertebrates. Gastropoda is the extant mollusk class with the greatest species richness, including marine, freshwater, and terrestrial lineages, and likely, highly diverse chemoreception systems. Here, we performed a comprehensive comparative genome analysis taking advantage of the chromosome-level information of two Gastropoda species, one of which belongs to a lineage that underwent a whole genome duplication event. We identified thousands of previously uncharacterized chemosensory-related genes, the majority of them encoding G protein-coupled receptors (GPCR), mostly organized into clusters distributed across all chromosomes. We also detected gene families encoding degenerin epithelial sodium channels (DEG-ENaC), ionotropic receptors (IR), sensory neuron membrane proteins (SNMP), Niemann–Pick type C2 (NPC2) proteins, and lipocalins, although with a lower number of members. Our phylogenetic analysis of the GPCR gene family across protostomes revealed: (i) remarkable gene family expansions in Gastropoda; (ii) clades including members from all protostomes; and (iii) species-specific clades with a substantial number of receptors. For the first time, we provide new and valuable knowledge into the evolution of the chemosensory gene families in invertebrates other than arthropods.

Freshwater Gastropod Diversity in The Selected Lotic Environment, Betong, Sarawak, Borneo

Freshwater Gastropoda can be considered as the biological indicator in ecosystems such as rivers, streams, lakes, and ponds. The objectives of this study are to identify freshwater gastropod species, diversity, and distribution along Sungai Penebak, Sungai Nanga Tiga, and Sungai Kabo in the Betong division. The study was conducted on 10 November 2020. A 50 m transect was laid on the riverbank of all three stations. The existing specimens were counted and collected from each sampling point and stored were taken to the laboratory for species identification. The diversity index and morphological study of freshwater gastropods were performed. Five species of freshwater gastropods belonging to four families were discovered. The five species of freshwater gastropods consisted of Sulcospira pageli, which shows great abundance, followed by Clea nigricans, Brotia costula, Pila ampullacea, and Vittina pennata. The diversity indices of collected Gastropoda species from the different stations, for instance, Shannon-Weiner diversity index (H’), Pielou’s evenness index (J’), and Margalef’s richness index were assessed; where station 3 showed higher diversity of Gastropoda compared to other two stations. The information presented in this paper might be helpful for ecological wealth studies and considered as the baseline data for the stream ecosystem in Sarawak, Malaysia.

Gut Bacteriomes and Ecological Niche Divergence: An Example of Two Cryptic Gastropod Species.

Symbiotic microorganisms may provide their hosts with abilities critical to their occupation of microhabitats. Gut (intestinal) bacterial communities aid animals to digest substrates that are either innutritious or toxic, as well as support their development and physiology. The role of microbial communities associated with sibling species in the hosts' adaptation remains largely unexplored. In this study, we examined the composition and plasticity of the bacteriomes in two sibling intertidal gastropod species, Littorina fabalis and L. obtusata, which are sympatric but differ in microhabitats. We applied 16S rRNA gene metabarcoding and shotgun sequencing to describe associated microbial communities and their spatial and temporal variation. A significant drop in the intestinal bacteriome diversity was revealed during the cold season, which may reflect temperature-related metabolic shifts and changes in snail behavior. Importantly, there were significant interspecies differences in the gut bacteriome composition in summer but not in autumn. The genera Vibrio, Aliivibrio, Moritella and Planktotalea were found to be predominantly associated with L. fabalis, while Granulosicoccus, Octadecabacter, Colwellia, Pseudomonas, Pseudoalteromonas and Maribacter were found to be mostly associated with L. obtusata. Based on these preferential associations, we analyzed the metabolic pathways' enrichment. We hypothesized that the L. obtusata gut bacteriome contributes to decomposing algae and detoxifying polyphenols produced by fucoids. Thus, differences in the sets of associated bacteria may equip their closely phylogenetically related hosts with a unique ability to occupy specific micro-niches.

Mollusks (Gastropoda, Bivalvia) from Miocene cold-seep deposits in northern Italy: revisions and additions

Here, we report on 33 molluscan species from Miocene ’Calcari a Lucina’ hydrocarbon-seep deposits in northern Italy. Three new species are described: the chilodontaid gastropod Putzeysia diversii sp. nov., the lucinid bivalve Miltha (sensu lato) romaniae sp. nov., and Sisonia ultimoi sp. nov., a heterodont bivalve of uncertain taxonomic affinity. Fourteen species are described in open nomenclature. The common but enigmatic gastropod species Phasianema taurocrassa is here suggested to belong to the seguenzioid genus Cataegis. Most gastropod species are inhabitants of the deep-sea floor in general, and are not restricted (obligate) to sites of hydrocarbon-seepage. The gastropod Putzeysia diversii sp. nov. and the bivalve Sisonia ultimoi sp. nov. are the geologically oldest members of their genera known to date. While the genus Putzeysia is geographically restricted to the NE Atlantic Ocean and the Mediterranean Sea, Sisonia ultimoi sp. nov. represents another link of the Miocene Mediterranean seep fauna to that of the central Indo-West Pacific Ocean.

IDENTIFIKASI MAKROZOOBENTOS SEBAGAI BIOINDIKATOR KUALITAS PERAIRAN DI PANTAI TELUK BENOA, BADUNG

Utilization of coastal waters for aquaculture activities or for other activities provides positive value for human welfare but can also provide the potential for reducing water quality. The decline in environmental quality can be seen from changes in components such as biology, chemistry, and beach physics. Changes in chemical and physical components cause sediment to decrease, which will affect the life of marine biotas, such as the community structure, especially the slow-moving and relatively settled biota on the bottom of the waters (macrozoobenthos). Macrozoobenthos are very appropriate to be used as an indicator of changes in water quality due to their benthic nature which is relatively silent or has low mobility so it is strongly influenced by the environment. The purpose of the study was to determine the structure of the macrozoobenthos community and the condition of seawater quality. There were 25 species of gastropods and 3 other classes. The macrozoobenthos species diversity index on the Benoa Bay Coast showed a moderate level of diversity with the highest value of 2.4576. The uniformity index at each station ranges from 0.0894 – 0.5337. The value of the dominance index ranges between 0.000004-0.7656. Based on the relative abundance, the macrobenthos community is dominated by the Gastropod class. The temperature values ??at each station were relatively the same, ranging from 29.3°C– 30.8°C, and the pH was in accordance with quality standards for macrozoobenthos growth. Some indicators of water quality are still below the quality standard threshold, but the concentration of phosphate (PO4) at all locations is already above the predetermined quality standard of 0.015 mg/L?.
 Keyword: Macrozoobenthos; Bioindicator; Benoa Bay; Bali

De novo genome and transcriptome assembly of Kelletia kelletii, a coastal gastropod and fisheries species exhibiting a northern range expansion

Understanding the genomic characteristics of non-model organisms can bridge research gaps between ecology and evolution. However, the lack of a reference genome and transcriptome for these species makes their study challenging. Here, we complete the first full genome and transcriptome sequence assembly of the non-model organism Kellet’s whelk, Kelletia kelletii, a marine gastropod exhibiting a poleward range expansion coincident with climate change. We used a combination of Oxford Nanopore Technologies, PacBio, and Illumina sequencing platforms and integrated a set of bioinformatic pipelines to create the most complete and contiguous genome documented among the Buccinoidea superfamily to date. Genome validation revealed relatively high completeness with low missing metazoan Benchmarking Universal Single-Copy Orthologs (BUSCO) and an average coverage of ∼70x for all contigs. Genome annotation identified a large number of protein-coding genes similar to some other closely related species, suggesting the presence of a complex genome structure. Transcriptome assembly and analysis of individuals during their period of peak embryonic development revealed highly expressed genes associated with specific Gene Ontology (GO) terms and metabolic pathways, most notably lipid, carbohydrate, glycan, and phospholipid metabolism. We also identified numerous heat shock proteins (HSPs) in the transcriptome and genome that may be related to coping with thermal stress during the sessile life history stage. A robust reference genome and transcriptome for the non-model organism K. kelletii provide resources to enhance our understanding of its ecology and evolution and potential mechanisms of range expansion for marine species facing environmental changes.

Species composition of macromolluscs in Barangay Talao-talao, Lucena, Quezon province, Philippines

Degradation of upland vegetation and the continuous environmental insults on coastal ecosystems negatively impact the inhabiting molluscs. In particular, macromolluscs present in the intertidal zones of coastal communities in the Philippines are directly affected by human activities and the fast-changing climate. However, a limited number of studies have investigated the effects of habitat alteration and degradation on the composition and diversity of the Philippines’ intertidal molluscs. Thus, this study assessed the species composition of macromolluscs in Lucena, Quezon, and the underlying environmental and habitat factors that may dictate the presence and abundance of these marine animals. To address these concerns, handpicking and purposive sampling of marine molluscs were conducted in the entire intertidal region of the sampling site. This study reported 62 different species at the intertidal zones of Lucena, Quezon, with species originating from the family Olividae being the most abundant organism among the sampled gastropod and bivalve species in the area. Analysis of the observational differences in molluscan habitat may highlight ecological factors affecting the diversity and abundance of the intertidal fauna. Continuous use of the shoreline for traditional fishing and the close proximity of the port of Lucena and human habitation to the coastal zone may also serve as underlying factors to the lack of live mollusc samples in the intertidal region nearest to the port. Together, these findings suggest a high species composition and abundance of macromolluscs inhabiting the intertidal zone of Lucena, Quezon, highlighting the drastic effects of changing marine ecosystems on the ability of various species to occupy a specific area in the marine environment.

Diversity of marine macro molluscan bivalves and gastropods in the intertidal areas of Barangay Paniman, Caramoan, Camarines Sur, Philippines

There have been very few studies on mollusk diversity in remote areas of the Philippines. The coastal areas of Caramoan, Camarines Sur, are ideal for studying marine molluscs because they have been discovered to be abundant, diverse, and essential to the locals’ livelihood. However, due to the remoteness of the mentioned area, this lack of information remains scientifically lacking. Thus, this study aimed to determine the diversity of marine macro-molluscan bivalves and gastropods in the intertidal areas of Barangay Paniman, Caramoan, Camarines Sur, Philippines. Purposive sampling and transect methods assessed the species composition, abundance, and occurrence of marine macro bivalves and gastropods. The Shannon-Wiener index was used to determine the area’s diversity. A total of 557 individual molluscs were sampled and classified, obtaining 43 species of bivalves from 32 genera and 18 families and 47 species of gastropods from 34 genera and 20 families. The family Veneridae had the highest among the bivalves, and the family Strombidae had the highest species richness among the gastropods. This study provided baseline information on the status of marine macro molluscan bivalves and gastropods in the intertidal area of Barangay Paniman, Caramoan, Camarines Sur, Philippines. As a result, this will provide solid empirical evidence for conservation and sustainability plans.

Invertebrate fauna of the Albian–Lower Cenomanian deposits in the Fars and Isfahan provinces (Firuzabad and Fasakhod sections), Zagros Basin, Central Iran

The Albian- Cenomanian deposits of the Kazhdumi Formation at Zagros Basin (Firuzabad section and Central Iran (Fasakhod section), represents a carbonate sedimentary succession and contain rich and diverse invertebrate macro fauna. Detailed studies on about 200 specimens of invertebrate macro fauna revealed from two stratigraphic intervals led to recognition of 5 species of gastropods; (Liopeplum? sp., Columbellina sp., Cryptaulax? sp., Turritella? sp., Pleurotomaria sp.), 3 species of ammonites; (Knemiceras duberterti, Sphenodiscus sp., Knemiceras persicum), 10 species of bivalves assemblages; (Ceratostreon flabellatum, Cardium? sp., Exogyra (Costagyra) olisiponensis, Neithea (Neithea) quinquecostata, Trigonia sp., Buchia? sp., Cardium? sp., Pseudogyra sp., Ontaria? sp., Nucula? sp., Pleuromia? sp., 1 species of echinoids; Dorocidaris taouzensis with a prolific horizon of Notopocorystes xizangensis of raninoid crabs. The absence of large gastropods and bivalves fauna and abundance of suspension-feeders indicated instability of the substrate, shallow marine paleoenvironment.and a medium energy condition.

Core gut microbes Cloacibacterium and Aeromonas associated with different gastropod species could be persistently transmitted across multiple generations

BackgroundStudies on the gut microbiota of animals have largely focused on vertebrates. The transmission modes of commensal intestinal bacteria in mammals have been well studied. However, in gastropods, the relationship between gut microbiota and hosts is still poorly understood. To gain a better understanding of the composition of gut microbes and their transmission routes in gastropods, a large-scale and long-term experiment on the dynamics and transmission modes of gut microbiota was conducted on freshwater snails.ResultsWe analyzed 244 microbial samples from the digestive tracts of freshwater gastropods and identified Proteobacteria and Bacteroidetes as dominant gut microbes. Aeromonas, Cloacibacterium, and Cetobacterium were identified as core microbes in the guts, accounting for over 50% of the total sequences. Furthermore, both core bacteria Aeromonas and Cloacibacterium, were shared among 7 gastropod species and played an important role in determining the gut microbial community types of both wild and cultured gastropods. Analysis of the gut microbiota at the population level, including wild gastropods and their offspring, indicated that a proportion of gut microbes could be consistently vertically transmitted inheritance, while the majority of the gut microbes resulted from horizontal transmission. Comparing cultured snails to their wild counterparts, we observed an increasing trend in the proportion of shared microbes and a decreasing trend in the number of unique microbes among wild gastropods and their offspring reared in a cultured environment. Core gut microbes, Aeromonas and Cloacibacterium, remained persistent and dispersed from wild snails to their offspring across multiple generations. Interestingly, under cultured environments, the gut microbiota in wild gastropods could only be maintained for up to 2 generations before converging with that of cultured snails. The difference observed in gut bacterial metabolism functions was associated with this transition. Our study also demonstrated that the gut microbial compositions in gastropods are influenced by developmental stages and revealed the presence of Aeromonas and Cloacibacterium throughout the life cycle in gastropods. Based on the dynamics of core gut microbes, it may be possible to predict the health status of gastropods during their adaptation to new environments. Additionally, gut microbial metabolic functions were found to be associated with the adaptive evolution of gastropods from wild to cultured environments.ConclusionsOur findings provide novel insights into the dynamic processes of gut microbiota colonization in gastropod mollusks and unveil the modes of microbial transmission within their guts.1dB18pPYxP-ygVgUJj2q9BVideo