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One means of eradicating invasive molluscs is through dewatering or desiccation. Here, I show a practical approach for determining desiccation tolerance of molluscs. Laboratory studies of desiccation tolerance are usually conducted at constant humidity levels, with the amount of time to death, provided as an end point. However, in the natural environment humidity can vary hourly and time to death at a constant humidity is not relevant. A more practical method to determine desiccation tolerance is by measuring water loss. Additionally, knowing the length–weight relationship and desiccation tolerance one can calculate the predicted desiccated weight of a mollusc that would ensure 95% mortality. I used this approach for two invasive aquatic snails, the red-rimmed melania, Melanoides tuberculata and the quilted melania Tarebia granifera . Snails were placed in individual dry vials and every 24 h a subset was weighed to determine water mass lost, followed by the addition of water to determine survival. Survival analyses were conducted to determine percent water mass lost that would result in 95% mortality. This approach for determining desiccation resistance can be a useful control tool for a variety of invasive organisms and is not dependent on temperature or humidity.

Molluscs are the second largest and most speciose invertebrate phylum after Arthropoda. There are around 7000 freshwater molluscs that play an important role in the ecosystem. Although many of these freshwater species are very restricted in their habitats, due to the increase in globalisation, trade, and transport, freshwater molluscs get introduced to new environments, becoming problematic to the native biodiversity and humans. Our compilation reveals 28 invasive freshwater molluscs globally, which reportedly cause serious problems to the native biodiversity, including economic loss, agriculture, and others. The major pathways of introduction for the freshwater molluscs are found to be accidental/unintentional (e.g. as hitchhikers with macrophytes, ballast water, aquarium waste disposal) and pet trade. We obtained the distribution records for 28 species from global databases like Global Biodiversity Information Facility (GBIF), iNaturalist, and the published and grey literature. The species distribution modelling reveals Europe, South America, and Eastern North America as the most vulnerable regions. Niche dynamics analysis shows 14 species with lower and nine species with high niche overlap across the native and introduced ranges. Two species i.e. Corbicula fluminea and Physella acuta follow niche conservatism.

We summarized existing knowledge on Dreissena polymorpha (the zebra mussel) and D. r. bugensis (the quagga mussel), including data on their taxonomy, systematics, evolution, life cycle, reproduction, feeding, growth and longevity, population dynamics, interspecific competition, habitat requirements, and distribution within and among waterbodies. We analyzed the history of spread of both species and the major pathways and vectors of their spread in Europe and North America. Special consideration was given to their ecological and economic impacts and their natural enemies, like waterfowl, fishes, and parasites, as well as the prevention of their introduction, early detection, control, and containment. We also outlined the most salient ecosystem services provided by zebra and quagga mussels, including water purification, nutrient recycling, culling the effects of eutrophication, biomonitoring, and their role as a food resource for fish and waterfowl. Finally, we identified major knowledge gaps and key studies needed to better understand the biology, ecology, and impacts of these aggressive freshwater invaders. Our review indicates that much crucial information on the quagga mussel is still missing, including key life history parameters, like spawning cues, fecundity, and longevity, particularly for the profundal zone of deep lakes.

With the biodiversity crisis continuing unchecked, we need to establish levels and drivers of extinction risk, and reassessments over time, to effectively allocate conservation resources and track progress towards global conservation targets. Given that threat appears particularly high in freshwaters, we assessed the extinction risk of 1428 randomly selected freshwater molluscs using the IUCN Red List Categories and Criteria, as part of the Sampled Red List Index project. We show that close to one-third of species in our sample are estimated to be threatened with extinction, with highest levels of threat in the Nearctic, Palearctic and Australasia and among gastropods. Threat levels were higher in lotic than lentic systems. Pollution (chemical and physical) and the modification of natural systems (e.g. through damming and water abstraction) were the most frequently reported threats to freshwater molluscs, with some regional variation. Given that we found little spatial congruence between species richness patterns of freshwater molluscs and other freshwater taxa, apart from crayfish, new additional conservation priority areas emerged from our study. We discuss the implications of our findings for freshwater mollusc conservation, the adequacy of a sampled approach and important next steps to estimate trends in freshwater mollusc extinction risk over time.

Invasion of alien species is one of the major environmental problems in the globalised world. Therefore, identifying pathways for the introduction and spread of alien species can help to mitigate their impact on invaded ecosystems. This study focused on the freshwater snail Gyraulus chinensis , which invades Europe from eastern Eurasia, where it is native. It was first recorded in Europe about 50 years ago and has since expanded its distribution. However, its origin and the mechanisms of its spread have not yet been studied. Therefore, we performed molecular identification and estimated its origin and dispersal mechanisms based on a literature review, molecular phylogenetics, and population genetics. We found that the haplotypes of G. chinensis in Europe are closely related to southern East Asia, namely Hong Kong, Taiwan, and the Ryukyu Islands. The results also suggest multiple introductions, mainly due to the diversity of haplotypes detected in European G. chinensis populations. Currently, the distribution and invasion of the species in the outdoor environments are concentrated in southern Europe, probably due to thermal constraints. However, the species has been recorded in many indoor habitats in the northern part of Europe, indicating a high potential for its spread in the warmer world.

In mollusk aquaculture, a large number of Vibrio species are considered major pathogens. Conventional methods based on DNA amplification and sequencing used to accurately identify Vibrio species are unsuitable for monitoring programs because they are time-consuming and expensive. The aim of this study was, therefore, to develop the MALDI-TOF MS method in order to establish a rapid identification technique for a large panel of Vibrio species. We created the EnviBase containing 120 main spectra projections (MSP) of the Vibrio species that are potentially responsible for mollusk diseases, comprising 25 species: V. aestuarianus, V. cortegadensis, V. tapetis and species belonging to the Coralliilyticus, Harveyi, Mediterranei, and Orientalis clades. Each MSP was constructed by the merger of raw spectra obtained from three different media and generated by three collaborating laboratories to increase the diversity of the conditions and thus obtain a good technique robustness. Perfect discrimination was obtained with all of the MSP created for the Vibrio species and even for very closely related species as V. europaeus and V. bivalvicida. The new EnviBase library was validated through a blind test on 100 Vibrio strains performed by our three collaborators who used the direct transfer and protein extraction methods. The majority of the Vibrio strains were successfully identified with the newly created EnviBase by the three laboratories for both protocol methods. This study documents the first development of a freely accessible database exclusively devoted to Vibrio found in marine environments, taking into account the high diversity of this genus.Key points• Development of a MALDI-TOF MS database to quickly affiliate Vibrio species.• Increase of the reactivity when faced with Vibrio associated with mollusk diseases.• Validation of MALDI-TOF MS as routine diagnostic tool.

In this review, we synthesize the current knowledge of the biology, ecology, and impact of Sinanodonta freshwater mussels (Bivalvia, Unionidae), native to East Asia, that have successfully invaded Europe, Central America, North Africa, and several Asian regions. The main introduction pathways of Sinanodonta were reconstructed based on DNA sequence data and distribution records. We show that invasive lineages of Sinanodonta belong to three species, namely, S. woodiana s. str. (“temperate invasive” lineage), S. pacifica (“tropical invasive” lineage), and S. lauta . Their generalist fish-dispersed larvae, short life span, high fecundity, use by humans for multiple purposes, and ability to establish populations in anthropogenically disturbed conditions were identified as crucial traits driving their invasions. Information on the consequences is scarcer, but Sinanodonta can impact native species through larval parasitism, host fish/food competition, and parasite transmission. In addition, ecosystem effects through their filtration—biodeposition—excretion activity and the occurrence of massive die-offs were detected. Ecosystem services and disservices have not yet been quantified, even at local scales, and management methods in the invasive range are understudied. A better understanding of Sinanodonta ecology, impacts, and management options is urgently needed to make informed decisions and set realistic and impactful restoration goals.

The Western Balkans hosts the richest subterranean aquatic gastropod fauna in the world. The main factors shaping intraspecies diversity are thought to be isolation and endemism. In the genus Belgrandiella, minute snails inhabiting subterranean waters and springs in Central Europe and Balkans, molecular studies have shown much fewer valid species than previously anticipated. The present study applies mitochondrial cytochrome c oxidase subunit I, histone 3, and RAPD analysis, to check the inter- and intraspecies genetic diversity in 36 Belgrandiella populations from caves, springs and interstitial aquifers. The level of gene flow is assessed to check if these snails form a widespread genetically uniform metapopulation or rather follow the highly endemic pattern. The studied populations have been assigned to six species. In the most widely distributed B. kusceri from 21 populations, 60 sequenced specimens represent 16 haplotypes. While the same haplotypes are present in distant populations, gene flow between the other populations is low. Nei distances for RAPD show no geographic pattern. The interspecies differences in COI evidently confirm the time of speciation in Pleistocene, before karstification, which rejects speciation within isolated caves. The pattern observed in Belgrandiella seems more similar to the one described in Montenegrospeum than in Kerkia.