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A prolific aquatic invasive species, the quagga mussel (Dreissena rostriformis bugensis), broadly impacts freshwater systems by altering ecosystem structure and function, damaging infrastructure, and limiting recreational boating opportunities. Quagga mussel populations have become established in several Western U.S. reservoirs which feed hydroelectric power facilities. Impacted facilities incur increased operational and maintenance costs and are at risk of power generation disruption. Current habitat suitability models suggest additional reservoirs are susceptible to successful invasion should introduction occur. The U.S. Bureau of Reclamation has detected additional quagga mussel introductions to numerous reservoirs, yet these populations appear not to have persisted. To further refine quagga habitat suitability models, we examined how reservoir surface elevation patterns, or storage dynamics, vary across reservoirs of three quagga mussel population statuses: established (i.e., established population confirmed), suspect (i.e., introduction detected without population establishment), and negative (i.e., no introduction detected). For this work, "drawdown events" or periodic water surface elevation declines, were operationally defined based on relevance to quagga desiccation mortality. Our comparisons of reservoir drawdown properties revealed that water-level declines were typically greater in suspect and negative reservoirs than in reservoirs with established quagga populations. Further, suspect reservoirs typically had less frequent, yet in many cases longer duration drawdown events than established reservoirs. Therefore, the magnitude and duration of drawdowns potentially have negative impacts on quagga population establishment in a novel environment. Managed large-magnitude and long-duration drawdowns may serve as a risk-reduction strategy for quagga invasion prevention. [ABSTRACT FROM AUTHOR]

The invasive alien false mussels Mytilopsis leucophaeata cochleata and Dreissena polymorpha (Dreissenidae) have established populations in the North Sea canal in the Netherlands that connects the harbours of Amsterdam with the North Sea. The favourable and unfavourable salinity ranges of both species were earlier studied in long-term outdoor mesocosm experiments. Their occurrence in salinity gradients in estuaries or canals connecting seaways to freshwater harbours provides information on their salinity tolerance under field conditions. By the combination of laboratory experiments and field data using the same source population a high predictability can be expected for establishment of the gradients facilitated by constructions. The reliability of experimentally derived salinity-tolerance limits for both dreissenid species was tested using data on their distribution in a salinity gradient of the littoral zone along the North Sea canal. The mussels used for the survival experiments in mesocosms were also collected from this canal. Favourable salinity ranges for adult survival in the mesocosms were 0.2 – 17.5 for M. leucophaeata cochleata and 0.2 – 6.0 for D. polymorpha. Unfavourable salinities were outside these ranges and led to high and fast mortality of these species. Mytilopsis leucophaeata cochleata was present over nearly the whole length of the North Sea canal with the highest densities close to the sea sluices where also the highest salinities and water temperatures were measured. Their densities in the canal decreased gradually at larger distances from the sea. Dreissena polymorpha co-exists with M. leucophaeata cochleata at the east end of the canal with low salinity due to the influence of freshwater of the river Rhine. The occurrence of D. polymorpha was restricted to a salinity below 4 and M. leucophaeata cochleata only occurred at a salinity above 1.5 (maximum value measured in the canal 9.2). Shorter salinity gradients with lower salinity ranges provided additional information on the co-existence of both species. Co-existence was observed at a salinity range of 1.5–3.3 (own data), 1.0–3.5 (Van Couwelaar and Van Dijk 1989), both in the North Sea canal, and 0.2–2.8, in the Canal through Voorne (Janssen and Janssen-Kruit 1967). These data correspond with studies of both species by Walton (1996) in the Hudson River (salinity range 0–3). Found salinity ranges in the North Sea canal for both species match with the tolerance results obtained by mesocosm experiments. A new invading dreissenid mussel Dreissena rostriformis bugensis and a mytilid Ischadium recurvum occur in the North Sea canal since 2006 and 2012, respectively. Competition between recent and earlier invaders is likely when salinity tolerances are similar. It has already been observed that D. rostriformis bugensis outcompetes D. polymorpha under freshwater conditions (Bij de Vaate et al. 2014; Matthews et al. 2014). Ischadium recurvum has the potential to colonize large parts of the canal and to be a strong competitor of M. leucophaeata cochleata (Goud et al. 2019). Since January 2022, the new ‘Zeesluis IJmuiden’ with the biggest locks in the world is in use, affecting the probability of population establishment of new introduced and invasive alien mussel species. [ABSTRACT FROM AUTHOR]

Compared to the data collected in 2016, pronounced changes in the malacofauna inhabiting the Shershnevskoye Reservoir (city of Chelyabinsk) were discovered in August 2022 at inshore sampling stations near the dam. Mollusks of the family Sphaeriidae have disappeared from the community of bivalves. The species Dreissena polymorpha (Pallas, 1771) of the family Dreissenidae predominated the malacofauna in 2022. Analysis of the size and age structure of the D. polymorpha population showed that the maximum age of mollusks was 5 years. The collected data indicate that D. polymorpha has successfully invaded the Shershnevskoye Reservoir in the period since 2016 and naturalized there. [ABSTRACT FROM AUTHOR]

The present study aimed to evaluate and compare feeding responses of the non-native and native bivalves, the dark false mussel Mytilopsis leucophaeata and the scorched mussel Brachidontes darwinianus, respectively, by offering different concentrations of seston from the coastal lagoon where these species coexist after dark false mussel introduction (Rodrigo de Freitas Lagoon, Rio de Janeiro-Brazil). For this purpose, independent laboratory experiments were carried out under five concentrations of seston to test the differences in clearance and ingestion rates of bivalves as a function of increasing concentrations of suspended particulate matter (SPM) on seston. In addition, from the integrated analysis of data obtained in experiments, it can be inferred about the efficiency levels of these species to remove SPM from seston and their effects on water turbidity and nutrient concentrations (total carbon, nitrogen, and phosphorus). Our hypothesis was that the non-native bivalve is more efficient to clear and ingest SPM from seston compared to the native one, which may lead to competitive advantages to the successful invasion of M. leucophaeata in coastal lagoons. Native species did not show a significant difference in clearance and ingestion rates with increasing concentrations of seston. Whereas the non-native bivalve showed a slight tendency to increase its clearance and ingestion rates with the increase in seston concentrations, evidencing its plasticity to adjust its feeding responses. The native bivalve was significantly more efficient to clear and ingest SPM at the lower seston concentration (i.e., close to natural concentrations found in the lagoon) compared to the non-native bivalve, which, on the other hand, showed a significant increase in its ingestion rates at the higher concentration tested (140 mg SPM L-1). Thus, the present results did not suggest food competition between the non-native M. leucophaeata and the native B. darwinianus in the introduced system. However, M. leucophaeata increased its feeding response with experimental increment in seston concentration, which suggests species ability to benefit from conditions of increased inputs of organic matter and higher primary production that could mediate its establishment in introduced systems. [ABSTRACT FROM AUTHOR]

Mytilopsis leucophaeata is an estuarine bivalve native from the Gulf of Mexico and Southeast USA, and it was introduced in Europe, Asia, Caribbean, South America and Northeast USA, showing massive colonization skills. In Brazil, the single invasion records of M. leucophaeata occur in the city of Rio de Janeiro, i.e., in the Rodrigo de Freitas Lagoon and in the Marapendi Lagoon. We conducted a new series of fieldworks in estuaries from the Rio de Janeiro state in order to evaluate the propagation of this invasive bivalve, aiming sites with proper salinities for the establishment of M. leucophaeata. A new record is given for the Maricá-Guarapina lagoon system, where M. leucophaeata mainly colonizes hard substrata (such as piers and rocks), reaching a mean density up to 43,375 specimens/m2; however, aggregates of M. leucophaeata were also observed in the soft substratum. Based on mitochondrial sequences, the taxonomic identification of the invasive bivalve was confirmed. The associated fauna to the agglomerates of M. leucophaeata in the lagoon system comprises amphipods, barnacles, tanaidaceans, isopods, crabs, polychaetes and snails. The expansion of M. leucophaeata requires a continuous investigation due to the great circulation of boats in the littoral of the Rio de Janeiro state and the increased chance of new introductions. [ABSTRACT FROM AUTHOR]

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Abstract The zebra mussel (Dreissena polymorpha) has all traits required to effectively colonize the aquatic environment and consequently reduce the diversity of native bivalves. We hypothesized that the zebra mussel chooses lake outlets characterized by medium current velocity and good food conditions. Here, we analyzed differences between bivalve abundances in lake outlets with varying environmental conditions such as the Carlson Index (trophy status), depth, width, current velocity, bed vegetation coverage, and type of bottom substrate. The results showed that the zebra mussel inhabits outlets that provide food (high trophy outlets) and have a mineral bed and a medium current velocity (ca. 0.2–0.3 m/s). The following main factors seem to be favorable for colonizing such outlets: (1) easy access to high amounts of food due to the increased density of the suspension drifting from the lake and (2) easy transport of the zebra mussel larvae from the lake to the downstream. The zebra mussel larvae drifting with the current may colonize the downstream. An increase in lake trophy may indirectly cause an increase in biological invasions in rivers.

Aim: To assess spatio‐temporal and taxonomic patterns of available information on the costs of invasive freshwater bivalves, as well as to identify knowledge gaps. Location: Global. Time period: 1980–2020. Taxon studied: Bivalvia. Methods: We synthesize published global economic costs of impacts from freshwater bivalves using the InvaCost database and associated R package, explicitly considering the reliability of estimation methodologies, cost types, economic sectors and impacted regions. Results: Cumulative total global costs of invasive macrofouling bivalves were $ 63.7 billion (2017 US$) across all regions and socio‐economic sectors between 1980 and 2020. Costs were heavily biased taxonomically and spatially, dominated by two families, Dreissenidae and Cyrenidae (Corbiculidae), and largely reported in North America. The greatest share of reported costs ($ 31.5 billion) did not make the distinction between damage and management. However, of those that did, damages and resource losses were one order of magnitude higher ($ 30.5 billion) than control or preventative measures ($ 1.7 billion). Moreover, although many impacted socio‐economic sectors lacked specification, the largest shares of costs were incurred by authorities and stakeholders ($ 27.7 billion, e.g., public and private sector interventions) and through impacts on public and social welfare ($ 10.1 billion, e.g., via power/drinking water plant and irrigation system damage) in North America. Average cost estimates over the entire period amounted to approximately $ 1.6 billion per year, most of which was incurred in North America. Main conclusions: Our results highlight the burgeoning economic threat caused by invasive freshwater bivalves, offering a strong economic incentive to invest in preventative management such as biosecurity and rapid response eradications. Even if the damages and resource losses are severely understated because economic impacts are lacking for most invaded countries and invasive bivalve species, these impacts are substantial and likely growing. [ABSTRACT FROM AUTHOR]

The zebra mussel (Dreissena polymorpha) has all traits required to effectively colonize the aquatic environment and consequently reduce the diversity of native bivalves. We hypothesized that the zebra mussel chooses lake outlets characterized by medium current velocity and good food conditions. Here, we analyzed differences between bivalve abundances in lake outlets with varying environmental conditions such as the Carlson Index (trophy status), depth, width, current velocity, bed vegetation coverage, and type of bottom substrate. The results showed that the zebra mussel inhabits outlets that provide food (high trophy outlets) and have a mineral bed and a medium current velocity (ca. 0.2–0.3 m/s). The following main factors seem to be favorable for colonizing such outlets: (1) easy access to high amounts of food due to the increased density of the suspension drifting from the lake and (2) easy transport of the zebra mussel larvae from the lake to the downstream. The zebra mussel larvae drifting with the current may colonize the downstream. An increase in lake trophy may indirectly cause an increase in biological invasions in rivers. [ABSTRACT FROM AUTHOR]

The introduction of mussels of the family Dreissenidae into the cooling pond of one of the nuclear power plants (NPP) of Ukraine, the Khmelnitsky NPP (north-western region), has caused significant changes both in the contour and in the pelagic parts of the techno-ecosystem. The following three periods were considered: (1) before the introduction of Dreissena polymorpha, (2) during the peak of its population development and (3) after the introduction of a second species of Dreissena and declining of abundance of Dreissenidae. We recorded a decrease in taxonomic richness and abundance of phytoplankton with the increase of the effect of D. polymorpha. No such changes were registered for the zooplankton community. The relationship between the biomass of phytoplankton and zooplankton were quite complex. In addition, the relations of diversity indicators of the phyto- and zooplankton communities were different during the three study periods: negative in the first, positive in the second and none in the third period. We concluded that the invasion of Dreissenidae into the water bodies and its effect on the ecosystems should be considered not only from the standpoint of their direct influence on the water transparency and phytoplankton abundance; this invasion could affect all the components of the pelagic and contour subsystems. [ABSTRACT FROM AUTHOR]

Impacts of dreissenid mussels (Dreissena spp.) on Great Lakes ecosystems are well documented, and a better understanding of mechanisms that cause variation in dreissenid abundance is needed. An outstanding question is how much dreissenid biomass is consumed by fish predation. A significant difficulty for investigating dreissenid consumption by fish is that dreissenids in stomachs are often a mix of indigestible shell and flesh, which can bias bioenergetics models and estimates of daily ration. Here, we develop an analysis to convert crushed shell and flesh mixtures found in fish diets to dry weight of digestible dreissenid flesh. Quagga Dreissena rostiformis bugensis and zebra Dreissena polymorpha mussels were used in separate dry weight analyses simulating stomach contents ranging from individual mussels to aggregates of each species. A species-specific dry weight relationship was observed when comparing flesh-only dry weight to total dry weight (shell + flesh) for individual dreissenid but not for aggregates. Thus, the model is applicable in providing more precise estimates of dreissenid flesh dry weight in fish diets. [ABSTRACT FROM AUTHOR]

Dreissenid mussels can alter nutrient cycling and algal productivity in many freshwater ecosystems. But their effects on sedimentary phosphorus dynamics remain largely undefined. Here, we report evidence that dreissenids affect the concentrations of five sedimentary phosphorus fractions and total phosphorus. During our study, zebra mussels were still common and coexisted with quagga mussels in many parts of the basin. The relative abundances varied across the basin, which we characterized as five west-to-east alternating zones where zebra mussels dominated zones I (coastal) and III, quagga mussels dominated zones II and IV, and few dreissenids were present in zone V. The phosphorus fractions exhibited variation concordant with and therefore potentially influenced by dreissenids. Concentrations of all fractions and TP were consistently greater in sediments where quagga mussels dominated than in sediments where zebra mussels dominated. The responses to the absence versus presence of dreissenids were mixed, with Res-P being significantly affected, NaCl-Pi and HCl-Pi being moderately affected, and NaOH-Pi being least affected. Although such dreissenid effects were somewhat altered by in-lake biogeochemical cycling and transfer, we found that elevated levels of NaCl-Pi in dreissenid-present sediments, especially in quagga-dominated sediments, could be linked to recent eutrophication and harmful algal blooms in the basin. [ABSTRACT FROM AUTHOR]

Early detection is paramount for attempts to remove invasive non-native species (INNS). Traditional methods rely on physical sampling and morphological identification, which can be problematic when species are in low densities and/or are cryptic. The use of environmental DNA (eDNA) as a monitoring tool in freshwater systems is becoming increasingly acceptable and widely used for the detection of single species. Here we demonstrate the development and application of standard PCR primers for the detection of two freshwater invasive species which are high priority for monitoring in the UK and elsewhere: the Dreissenid mussels; Dreissena rostriformis bugensis (Andrusov, 1987) and D. polymorpha (Pallas, 1771). We carried out a rigorous validation process for testing the new primers, including DNA detection and degradation experiments in mesocosms, and a field comparison with traditional monitoring protocols. eDNA from single individuals of both mussel species could be detected within four hours of the start of the mesocosm experiment. In field trials, the two mussel species were detected at all sites where the species are known to be present, and eDNA consistently outperformed traditional kick-net sampling for species detection. These results demonstrate the applicability of standard PCR for eDNA detection of freshwater invasive species. [ABSTRACT FROM AUTHOR]

Aquatic part of Khmelnitsky Nuclear Power Plant teсhnoeсosуstem was studied during the periods of operation of one (1998–2001) and two power units (2005–2016). Changes in species composition, as well as abundance and biomass dynamics of phytoplankton, zooplankton, zoobenthos, zooperiphyton, and higher aquatic plants in the cooling pond and channels were found to be related to both technogenic and biogenic factors. The invasion of alien species constantly occurred in the teсhnoeсosуstem. Thirteen invader species were noted during the period of research. Invasion of Zebra mussel (Dreissena polymorpha) and submerged plant Najas marina prevented regular operation of the system; sponge Eunapius carteri reached mass development. Some invaders appeared for a short period; others naturalized, but did not reach the mass development. The phenomenon of contourization associated with the invasion and the mass development of the powerful filter feeder – Zebra mussel was observed in the ecosystem during the period of research. Signs of contourization (for example, a significant increase of water transparency) were observed already in years 2–3 after the invasion of the clam; significant changes in the pelagic subsystem were observed only in years 5–6. At the time of the invasion of the second dreissenid species (D. bugensis), population of D. polymorpha was in the stage of stabilization at low level of abundance. The assumption of the possible outbreak of D. bugensis abundance during the first years after its invasion was not confirmed. Thus, the successional processes in the teсhnoeсosуstem are determined not only by technogenic and natural abiotic, but also biotic factors

Caves are some of the least-known ecosystems on Earth and long-term ecological studies and population size estimates are very rare. Genus Congeria is a Tertiary relict that comprises three species from Dinaric karst area; C. kusceri, C. jalzici and C. mulaomerovici, each with very limited distribution. They are the only known cave bivalves and in contrast to many other cave species, they form populations with high densities. We estimated that the population of C. kusceri in Jama u Predolcu is between 72,454 and 72,906 individuals. The highest density occurred between one and three meters depth, and reached maximum of 1,625 individuals per square meter. Here we also present the results of a two-year water temperature and water level survey in several C. kusceri and C. jalzici localities. Data loggers showed that C. jalzici occurs in colder caves and higher water level oscillations then C. kusceri. From our data, it is obvious that the natural hydrological conditions in Congeria habitats were seriously altered. This and a series of other threats led to Congeria species being highly endangered. During low water levels, a part of the bivalve population becomes exposed to air in most localities. Uniquely, they are active during that period and are able to survive those conditions for more than 2 months.

An inspection was carried out at shrimp farms located South West of Lake Maracaibo (Zulia State, Venezuela), with high incidences of mussel bivalve. Morphological and genetic analysis helped to identify the species as the dark false mussel Mytilopsis leucophaeata Conrad, 1831, and this is the first record of the species from tropical waters of northern South America. The highest incidences of mussels were detected in ponds and channels but no live mussels were observed in the coastal intertidal area surrounding the entrances of the farms, although empty shells were detected there, suggesting their former presence. The environmental conditions of the artificial system of shrimp culture, is a niche suitable for the proliferation of the bivalve. The consequences of the presence of this bivalve in the production of shrimp are discussed. [ABSTRACT FROM AUTHOR]

Highlights • Interactions among stressors in ecosystems are common but hard to predict. • We identified interactions by pairing a systematic review with expert elicitation. • Many potential interactions (esp. synergies) were proposed but poorly studied. • Nutrient loading and invasive species were often the stressors in these interactions. • We used a conceptual model to integrate several potential interactions. Abstract Co-occurrence of environmental stressors is ubiquitous in ecosystems, but cumulative effects are difficult to predict for effective indicator development. Individual stressors can amplify (synergies) or lessen (antagonisms) each other's impacts or have fully independent effects (additive). Here we use the Laurentian Great Lakes, where a multitude of stressors have been studied for decades, as a case study for considering insights from both a systematic literature review and an expert elicitation (or structured expert judgment) to identify stressor interactions. In our literature search for pairs of stressors and interaction-related keywords, relatively few studies (9%, or 6/65) supported additive interactions with independent stressor effects. Instead, both antagonisms (42%, or 27/65) and synergies (49%, or 32/65) were common. We found substantial evidence for interactions of invasive dreissenid mussels with nutrient loading and between pairs of invasive species (predominantly dreissenids × round goby), yet both sets of records included mixtures of synergies and antagonisms. Complete quantification of individual and joint effects of stressors was rare, but effect sizes for dreissenid mussels × nutrient loading supported an antagonism. Our expert elicitation included discussion in focus groups and a follow-up survey. This process highlighted the potential for synergies of nutrient loading with dreissenid mussels and climate change as seen from the literature review. The elicitation also identified additional potential interactions less explored in the literature, particularly synergies of nutrient loading with hypoxia and wetland loss. To stimulate future research, we built a conceptual model describing interactions among dreissenid mussels, climate change, and nutrient loading. Our case study illustrates the value of considering results from both elicitations and systematic reviews to overcome data limitations. The simultaneous occurrence of synergies and antagonisms in a single ecosystem underscores the challenge of predicting the cumulative effects of stressors to guide indicator development and other management and restoration decisions. [ABSTRACT FROM AUTHOR]

First records of invasive bivalve freshwater mollusc species Mytilopsis leucophaeata (Conrad, 1831) and Corbicula fluminalis (O. F. Müller, 1774) in Georgia are reported. No native or alien extant dreissenid species have ever been recorded form this region so far. A finding of C. fluminalis in Georgia is also a new record for the country though this species inhabits the rivers of adjacent Azerbaijan. Apart from two mentioned bivalve molluscs three non-indigenous gastropod species are registered from Georgia: freshwater Ferrisia californica (Rowell, 1863) and Physella acuta (Draparnaud, 1805) and land snail Eobania vermiculata (O. F. Müller, 1774). [ABSTRACT FROM AUTHOR]

Fauna Europaea provides a public web-service with an index of scientific names (including important synonyms) of all living European land and freshwater animals, their geographical distribution at country level (up to the Urals, excluding the Caucasus region), and some additional information. The Fauna Europaea project covers about 230,000 taxonomic names, including 130,000 accepted species and 14,000 accepted subspecies, which is much more than the originally projected number of 100,000 species. This represents a huge effort by more than 400 contributing specialists throughout Europe and is a unique (standard) reference suitable for many users in science, government, industry, nature conservation and education. For the Mollusca-Bivalvia, data from 5 families (Margaritiferidae, Unionidae, Sphaeriidae, Cyrenidae, Dreissenidae) containing 55 species are included in this paper. European freshwater bivalves belong to the Orders Unionoida and Cardiida. All the European unionoids are included in the superfamily Unionoidea, the freshwater mussels or naiads. The European cardiids belong to the following three superfamilies: Cardioidea, Cyrenoidea and Dreissenoidea. Among the Unionoidea there are the most imperilled animal groups on the planet while the Cardioidea includes the cosmopolitan genus Pisidium, the Cyrenoidea the Asiatic clam (Corbicula fluminea) and the Dreissenoidea the famous invasive zebra mussel (Dreissena polymorpha). Basic information is summarized on their taxonomy and biology. Tabulations include a complete list of the current estimated families, genera and species.

Highlights • Biomarker responses in sympatric dreissenid populations were studied. • Impact of diverse stressors was assessed both in the field and in laboratory. • Different biomarker responses were observed between species and populations. • These differences are probably related to invasion dynamics and local adaptation for both species. • Some advices are provided concerning the use of these species for biomonitoring. purpose. Abstract Dreissenid mussels, well-known invaders of the northern hemisphere, also constitute good biomonitors for freshwater quality assessment. Whereas the oldest, Dreissena polymorpha , is relatively well-known, the new invasive, Dreissena rostriformis bugensis , has been very little characterized. The aim of this study was to compare subcellular biomarker responses within these species, by taking into account inter- and intra-specific variability in biomarker responses during a multi-stress assessment. Indeed, due to local environmental conditions and genetic background, biomarker responses can be different between populations of a given species, not only between species. To evaluate these differential responses, we sampled mussels on two sites where they are both present in sympatry (plus another D. r. bugensis population), and we exposed these populations in laboratory to different stressors: thermal stress (12 or 17 °C), dietary stress (fed or unfed), contamination (nickel at 0, 20 and 500 μg L−1) and exposure duration (0, 4 or 8 days). Results mainly evidenced strong inter-species and inter-population differences, underlining the need to discriminate correctly between the two species and to know well the populations used in biomonitoring. Results also evidenced thermal and food stress-related effects. The numerous data obtained during this multi-stress experiment also highlight the complexity of working on several stressors and analysing the associated results. [ABSTRACT FROM AUTHOR]

Lake stratification produces sharp gradients in temperature and pelagic resources which have cascading effects on the traits of aquatic populations, including invasive species and their ecosystem impacts. We study the consequences of such common environmental gradients on the demography of quagga mussels, one of the world's most aggressive invasive species. Coupling a series of in situ experiments with a biophysical model of the pelagic community, we quantify mussel growth and recruitment in littoral vs. profundal benthic habitats of eastern Lake Erie. We found that both severe food depletion and cold temperatures in the hypolimnion during summer stratification cause mussels to grow twice as slowly and currently inhibit recruitment in profundal compared to littoral habitats. Together with the high biomass and large mean mussel size found in long‐term monitoring surveys in the profundal habitats, our results imply that mussels successfully colonizing profundal habitats have relatively long lifespans with low growth rates, and therefore lower productivity, compared to mussels in shallow areas. Consequently, the bulk of dreissenid biomass in Lake Erie and other Great Lakes found in the vast but resource‐poor profundal habitats may have very limited impacts on epilimnetic communities compared to mussels in littoral areas. By contrast, mussels in profundal habitats strongly reduce food availability to hypolimnetic communities throughout the year. Thus, our results explain how the ecosystem impacts of sessile freshwater invaders are likely to vary among habitats and lakes depending on the relative size of profundal populations and the extent of stratification. [ABSTRACT FROM AUTHOR]

The genus Mytilopsis includes some of the most invasive estuarine bivalves in the world, and M. leucophaeata (native to the Gulf of Mexico) and M. sallei (indigenous in the Caribbean Sea) are the most often reported species. Molecular investigations of the COI gene in invasive populations of M. leucophaeata in Europe found only one haplotype, whereas the invasive M. sallei in Asia had high haplotype diversity. The present study investigated COI variability of invasive populations previously identified as M. leucophaeata in Brazil, located at the cities of Recife and Rio de Janeiro. Our genetic analysis revealed that the record of M. leucophaeata from Recife appears erroneous; this population forms a clade adjacent to but genetically separated from the Asian M. cf. sallei. Similarly, samples from Rio de Janeiro clustered close to but not within European/North American sequences of M. leucophaeata. The Automatic Barcode Gap Discovery test suggested the existence of three species: M. leucophaeata, M. cf. sallei (Asia), and M. cf. sallei (Recife), which merit confirmation with nuclear DNA sequences. The discovery of two lineages of Mytilopsis in Brazil augments concerns about their expansion. [ABSTRACT FROM AUTHOR]

Abstract: Dreissenid mussels Dreissena bugensis (quagga mussel) and Dreissena polymorpha (zebra mussel) are prolific invasive species to the freshwaters of the United States and Western Europe. In the Great Lakes, D. polymorpha has initially dominated the system since its invasion in the mid‐1980s; however, recently D. bugensis has displaced D. polymorpha as the dominant species. Dreissena bugensis has several competitive advantages over D. polymorpha, including greater tolerances to deeper and colder waters and lower respiration rates. Nevertheless, physiological differences between the species remain largely unknown. The oxidative stress response is a mechanism used by all organisms to mitigate environmental stress by reducing oxygen radicals in the body, and comparing this mechanism between similar species can be useful for understanding how different species compete in aquatic environments. We compared oxidative stress biomarkers (lipid peroxidation [LPO] and catalase [CAT] activity) in mussels after exposure to 4 stressors (i.e., high densities, temperature, hypoxia, and polychlorinated biphenyls [PCBs]) independently and in combinations of 2 stressors. Overall, D. bugensis had lower LPO and CAT activity than D. polymorpha when exposed to single stressors; however, in multiple stressor treatments D. bugensis had increased LPO, especially with high temperatures and PCBs. The lower lipid damage in D. bugensis compared with D. polymorpha under single stressor conditions may come at the cost of the ability to respond to multiple stressors. Environ Toxicol Chem 2018;37:1643–1654. © 2018 SETAC [ABSTRACT FROM AUTHOR]

Stress biomarkers, which can outline impacts of contaminants in aquatic biota at the biochemical level, are increasingly used as early warning tools in environmental monitoring. Reliable biomarker based assessment schemes, however, request appropriate knowledge of baseline levels of selected endpoints, and the potential influence of a range of natural influencing factors (both abiotic and biotic) as well. In this study, we examined the interspecies variability of various biomarkers (metallothioneins (MT), ethoxyresorufin-O-deethylase activity (EROD), lipid peroxidation (LPO), DNA strand breaks (DNA_sb), vitellogenin-like proteins (Vtg)) in Dreissena polymorpha and Dreissena bugensis inhabiting either pristine- or moderately impacted sites of Lake Balaton (Hungary). Levels of all biomarkers considered revealed low interspecies variability in the two dreissenid species at all sampling sites, with consistently higher (but statistically insignificant) values in Dreissena polymorpha . Levels of all biomarkers varied within the two investigated seasons, with significant influence of the reproduction cycle particularly on the levels of metallothioneins and vitellogenin-like proteins. Each biomarker considered was elevated by October, with significantly higher values in the mussels inhabiting harbours. Insignificant spatial and temporal variability in the general health indicators (condition index, total protein content) of dreissenids was observed, which, in parallel with evident rise in biomarker levels, apparently suggest that the anthropogenic impacts in harbours affect mussel fitness yet at sub organismal level. Our data might serve useful basis for future environmental monitoring surveys, especially in habitats where the progressive replacement of Dreissena polymorpha by Dreissena bugensis is taking place, as the interspecies variability in susceptibility to chemical stress of the two species is well comparable. [ABSTRACT FROM AUTHOR]

In this study, we investigated larval settlement and metamorphosis of the invasive foulerMytilopsis salleiexposed to ions, neurotransmitters and blockers inhibiting their respective actions. Excess K+effectively induced larval settlement and metamorphosis, while the voltage-gated potassium channel blocker, TEA, significantly inhibited the K+inducing effect, suggesting that a voltage-gated potassium channel may play a role inM. salleisettlement and metamorphosis. Excess Ca2+did not induce larval settlement and metamorphosis, while Mg2+andinhibited both. Among the neurotransmitters, GABA did not induceM. salleilarvae to settle and metamorphose at 10−6–10−4 M concentrations, while 5 × 10−5–10−4 Ml-DOPA (a dopamine precursor), 5 × 10−6–10−4 M dopamine (an epinephrine precursor) and 5 × 10−5–10−4 M epinephrine significantly induced larval settlement and metamorphosis, indicating the presence of an epinephrine biosynthesis pathway in this species and its role in the regulation of larval settlement and metamorphosis. Furthermore, the inducing effect of dopamine onM. salleisettlement and metamorphosis was inhibited by SCH23390, a selective D1 dopamine receptor antagonist. Similarly, the inducing effect of epinephrine was inhibited by chlorpromazine, anα1-adrenergic antagonist, suggesting that the D1 dopamine receptor andα1-adrenoceptor may play active roles in the processes of settlement and metamorphosis ofM. salleilarvae. Here, we have shown for the first time the responses of larval settlement and metamorphosis of dreissenid mussels to pharmacologically active compounds. The results provide new insights into the biochemical mechanisms underlying larval settlement and metamorphosis ofM. sallei, which may be useful to develop effective strategies to control this invasive fouling organism. [ABSTRACT FROM PUBLISHER]

Biomarkers of oxidative stress such as catalase (CAT), glutathione S-transferase (GST), glutathione reductase (GR) activity, and malondialdehyde and reduced glutathione content, as well as heavy metal concentrations (HM: Pb, V, Cr, Mn, Co, Ni, Cu, Zn, and Cd), were studied in Dreissena polymorpha tissues. Mussels were collected on three sites located on the Rybinskoe Reservoir different in levels of anthropogenic pressure: the most polluted sites were 1 and 2 and site 3 was relatively clean. Mussels from sites 1 and 2 had higher concentrations of HM (Pb, V, Cr, Mn, Ni, Cu, and Mn) and their response to the pollutant action was manifested in increased processes of lipid peroxidation (LPO), the activation of CAT, and elevated level of GHS. [ABSTRACT FROM AUTHOR]

This study presents a species-specific DNA-based marker for detection of the zebra mussel Dreissena polymorpha, recognized as one of the worst invasive species worldwide., The marker was developed in silico and experimentally tested on environmental samples. Gel and capillary electrophoreses for visualization of the PCR products were compared., Marker specificity and sensitivity were assessed in vitro by cross-amplifications and serial dilutions, respectively. The method allows detecting at least 0.7 ng of Dreissena DNA per μL and cross-species amplification was not found in any case., Next-generation sequencing (NGS) metabarcoding (PCR amplification and massive sequencing of a DNA barcode) was used as an independent method for verifying presence of Dreissena DNA molecules in environmental plankton samples collected from the south-eastern Baltic Sea., The consistency between NGS results reporting presence of Dreissena and positive PCR amplification of the marker from the plankton samples confirmed the efficacy of this highly reproducible, fast, cheap and technically easy method., Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Caves are some of the least-known ecosystems on Earth and long-term ecological studies and population size estimates are very rare. Genus Congeria is a Tertiary relict that comprises three species from Dinaric karst area; C. kusceri, C. jalzici and C. mulaomerovici, each with very limited distribution. They are the only known cave bivalves and in contrast to many other cave species, they form populations with high densities. We estimated that the population of C. kusceri in Jama u Predolcu is between 72,454 and 72,906 individuals. The highest density occurred between one and three meters depth, and reached maximum of 1,625 individuals per square meter. Here we also present the results of a two-year water temperature and water level survey in several C. kusceri and C. jalzici localities. Data loggers showed that C. jalzici occurs in colder caves and higher water level oscillations then C. kusceri. From our data, it is obvious that the natural hydrological conditions in Congeria habitats were seriously altered. This and a series of other threats led to Congeria species being highly endangered. During low water levels, a part of the bivalve population becomes exposed to air in most localities. Uniquely, they are active during that period and are able to survive those conditions for more than 2 months. [ABSTRACT FROM AUTHOR]

This article presents results of long-term studies of the communities of Zebra mussel and Quagga mussel in the cooling pond of the Chernobyl Nuclear Power Plant (Ukraine). The peculiarities of the sequential invasion of these two species and the formation of consortium-type communities by them are considered. [ABSTRACT FROM AUTHOR]

The data on the abundance and biomass of dreissenid underyearlings in macrophyte stands in different zones of the mouth part of a small tributary of Rybinsk Reservoir are presented. The highest density and biomass of underyearlings are recorded in the transient zone of the reservoir and the river mouth cross section. It is shown that the number of dreissenid underyearlings inhabiting the mouth area has not changed considerably in the years with unfavorable meteorological conditions. [ABSTRACT FROM AUTHOR]

The abundance dynamics of adult dreissenids ( Dreissena polymorpha (Pallas) and D. bugensis Andrusov) and of their larvae and the spatial distribution of the abundance of veligers and their role in the functioning of the plankton community have been analyzed on the basis of the data of original long-term monitoring (2004-2013) in Rybinsk Reservoir. The dreissenid veligers are most abundant in the summer time (July to August) when their number is comparable to that of the filter-feeding crustaceans and their biomass is close to that of rotifers. Before 2010 the production of veligers during the vegetation season comprised about 5% of the production of metazooplankton and the food consumption was about 1% of the primary production of phytoplankton. Pelagic invertebrate predators consumed about 90% of the production of veligers for the vegetation period. After 2010, the abundance of dreissenid larvae and their functional characteristics decreased by a factor of 5-6. Trophic relationships between zooplankton and veligers are discussed. [ABSTRACT FROM AUTHOR]

The results of our long-term studies of populations of two dreissenid species ( Dreisena polymorpha Pallas, 1771 and D. bugensis Andrusov, 1897) in Rybinsk and Gorkii reservoirs have been analyzed. New habitats of D. bugensis have been found in Rybinsk Reservoir. [ABSTRACT FROM AUTHOR]

This review summarizes published data on the genetic markers used in studies of dreissenide invasions. Causes of genetic differences between local populations are discussed. It is shown that information about the genetic diversity of populations obtained by marker polymorphism analysis should be compared to study invasion directions. [ABSTRACT FROM AUTHOR]

Silver carp (Hypophthalmichthys molitrix) and bighead carp (H. nobilis) are poised to invade the Laurentian Great Lakes. Zebra mussels (Dreissena polymorpha) and quagga mussels (D. rostriformis bugensis) have shifted nutrient pathways towards the benthos, partly through deposition of feces and rejected food particles called biodeposits. When biodeposit material was fed to bighead and silver carp, they fed on the material, but on average lost weight. Energy density between fed and unfed fish did not differ, but a few individual fish did gain weight on the biodeposits diet. Our results demonstrate that biodeposits might be considered a supplemental food for bigheaded carps. [ABSTRACT FROM AUTHOR]

Rapid assessment sampling for target species is a fast cost-effective method aimed at determining the presence, abundance and distribution of alien and native harmful aquatic organisms and pathogens that may have been introduced by shipping. In this study, the method was applied within a large tropical port expected to have a high species diversity. The port of Kaohsiung was sampled for bivalve molluscan species that attach using a byssus. Such species, due to their biological traits, are spread by ships to ports worldwide. We estimated the abundance and distribution range of one dreissenid ( Mytilopsis sallei ) and four mytilids ( Brachidontes variabilis , Arcuatula senhousa , Mytilus galloprovincialis , Perna viridis ) known to be successful invaders and identified as potential pests, or high-risk harmful native or non-native species. We conclude that a rapid assessment of their abundance and distribution within a port, and its vicinity, is efficient and can provide sufficient information for decision making by port managers where IMO port exemptions may be sought. [ABSTRACT FROM AUTHOR]

The benthic stages of Dreissenidae and Mytilidae may be dispersed over long distances while attached to ship hulls. Alternatively, larvae may be transported by water currents and in the ballast and bilge water of ships and vessels. To gain insight into dispersal potential and habitat suitability, survival of the benthic stages of two invasive dreissenid species ( Dreissena polymorpha and Mytilopsis leucophaeata) and one mytilid species ( Mytilus edulis) chosen based on their occurrence in fresh, brackish and sea water, respectively, were tested in relation to salinity. They were exposed to various salinities in mesocosms during three long-term experiments at outdoor temperatures. Mussel survival was studied without prior acclimation, reflecting conditions experienced when attached to ship hulls while travelling along a salinity gradient from fresh or brackish water to sea water, or vice versa. Initially, mussels react to salinity shock by temporarily closing their valves, suspending ventilation and feeding. However, this cannot be maintained for long periods and adaptation to higher salinity must eventually occur. Bivalve survival was monitored till the last specimen of a test cohort died. The results of the experiments allowed us to distinguish favorable (f.: high tolerance) and unfavorable (u.: no or low tolerance) salinity ranges in practical salinity units (PSU) for each species, viz. for D. polymorpha 0.2-6.0 PSU (f.), 7.0-30.0 PSU (u.), for M. leucophaeata 0.2-17.5 PSU (f.), 20.0-30.0 PSU (u.) and for M. edulis 10.5-36.0 PSU (f.), 0.2-9.0 and 40 PSU (u.). At the unfavorable salinities, all mussels died within 14 days of initial exposure with the exception of M. edulis (23-30 days). The maximum duration of survival of single specimens of D. polymorpha was 318 days at a salinity of 3.2 PSU, of M. leucophaeata 781 days at 15.0 PSU and of M. edulis 1052 days at 15.0 PSU. The number of days survived was compared with the duration of actual ship voyages to estimate the real world survival potentials of species dependent of salinity changes, travel distances and durations. The conclusion is that salinity shocks during the trip were survived within the favorable salinity range but that the species tolerate only for a few weeks the unfavorable salinity range. This functions as a barrier for dispersal. However, at faster and more frequent shipping in the future salinity can become no longer very important as a dispersal barrier. [ABSTRACT FROM AUTHOR]

Nuisance growth of the alga Cladophora, reported from Lake Ontario since the 1930s, abated in the decades following implementation of phosphorus control measures in the 1970s. Our examination of beach fouling records and historical observations of algal biomass has confirmed literature reports that a resurgence in nuisance growth of Cladophora has occurred since invasion of Great Lakes waters by dreissenids. Our findings indicate that the growth rate of Cladophora (specific rate of net photosynthesis) has decreased by 44% since 1972 in response to phosphorus controls. However, improved transparency, a response to mussel activity, has increased the maximum depth colonizable by Cladophora by a factor of 5 over that same interval. The net result is a sixfold increase in production potential since the late 1980s (the Post-P Management II Period) and a threefold increase since the 1970s (the Pre-P Management Period). Although the Cladophora resurgence has been driven by dreissenid modification of the light environment, phosphorus management remains the only alternative for reversing and ameliorating nuisance conditions. Elucidation of the nature of the Cladophora resurgence will aid decision-makers in maintaining a focus on phosphorus management as the appropriate means of remediating nuisance growth of the alga. [ABSTRACT FROM AUTHOR]

Dreissena spp. (zebra and quagga mussels) are invasive to North America and increase light to the benthos, provide hard structure for algal attachment, and may contribute limiting nutrients to benthic algae, thereby facilitating algal blooms. We conducted experiments to determine how Dreissena affect nutrient stoichiometry and growth of Lyngbya wollei and Cladophora glomerata, two benthic algal species recently increasing in biomass in parts of the Laurentian Great Lakes, combined with a field survey to determine the likelihood of L. wollei co-occurrence with Dreissena. L. wollei had a significantly higher concentration of carbon, nitrogen, phosphorus, potassium, and sulfur when grown with live Dreissena. C. glomerata had greater biomass in tanks with live Dreissena, but did not have significant increases in nutrient concentration like L. wollei did. Neither algal species increased in growth due to the added structure of Dreissena shells. L. wollei biomass was greater in the presence of Dreissena during 1 year (of two) of our field survey. This field survey also showed that L. wollei and Dreissena are likely to co-occur. These results suggest that Dreissena provide several nutrients to benthic algae, and these added resources can promote algal growth and consequently blooms. [ABSTRACT FROM AUTHOR]