Freshwater Bivalve Molluscs Research Articles

Первые находки беззубки Anodonta anatina (Linnaeus, 1758) (Unionidae, Bivalvia) в р. Синяя - бассейн р. Лена, Саха (Якутия)

The first data on the freshwater bivalve mollusks Anodonta anatina (Linnaeus, 1758) in the Sinyaya River, the left tributary of the Lena River, found within the Sinyaya Pillars natural park, are presented. The information on the species occurrence in the Lena River basin in the Sakha Republic (Yakutia) is generalized.

THE BIOCHEMICAL RESPONSES OF BIVALVE MOLLUSCS TO NEUROLEPTIC CHLORPROMAZINE ARE COMPARABLE WITH THE RESPONSES OF HIGHER VERTEBRATES

Pharmaceuticals such as chlorpromazine (Cpz) are emerging aquatic pollutants with potential effects on non-target organisms. However, its effects on aquatic organisms remain limited and inconclusive. The aim of this study was to compare the responses to Cpz in marine and freshwater bivalve molluscs. Methods. Mytilus galloprovincialis and Unio tumidus were exposed to pM and nM concentrations of Cpz for 14 days and analysed 16 parameters, including cytotoxicity, oxidative/reductive stress responses, metallothionein concentration and biotransformation enzymes in the digestive gland. Results. In both species, Cpz increased EROD activity, possibly leading to the formation of reactive metabolites. Marine mussels exposed to Cpz I and II showed increased GST activity, suggesting detoxification, whereas freshwater mussels showed decreased GST activity, suggesting higher Cpz toxicity. Activation of the GTPase dynamin in U. tumidus exposed to Cpz I confirmed the effect of Cpz on endocytosis. Oxidative stress responses were observed in both species, with changes in oxidative/reductive stress responses, suggesting toxic effects of Cpz. GSH and metallothionein concentrations increased in all exposures, while the NADH/NAD+ ratio increased significantly in U. tumidus. Loss of lysosomal membrane stability was observed in all exposed groups, with CtD efflux detected only in mussels. Differences in caspase-3 activity were also observed between species. Conclusion. Cpz showed adverse effects on vertebrates at μM concentrations, while mussels were affected at pM to nM concentrations, indicating concentration-dependent interspecies effects. Stress responses were similar between species, suggesting that marine molluscs are a potential model for assessing the adverse effects of Cpz on higher vertebrates.

Effect of Mercury on Behaviour of the Freshwater Bivalves L. marginalis in Different Time Hours

The present study includes the behavioral changes of freshwater bivalve mollusks L. marginalis due to acute toxicity of mercury. Different physiological and morphologically changes were observed in experimental animals it includes protective response, foot movements and its secretion, response to external stimuli, mucus secretion of gills and diapedesis. In this concept to improve that any toxicants or any molluscicide were responsible for the alternations in behavioural of animal body. From obtained results, we concluded the toxicity of mercuric chloride was responsible for the behavioral changes in freshwater bivalve mollusks L. marginalis.

NEW DATA ON RELATIONSHIPS BETWEEN FISHES (CYPRINIDAE) AND MOLLUSKS (BIVALVIA, MARGARITIFERIDAE, UNIONIDAE) IN THE RUSSIAN FAR EAST

The fi ndings of bitterling (Rhodeus sericeus) eggs and larvae in the gill chambers of freshwater bivalve mollusks from Razdolnaya River basin are discussed. Bitterling eggs and larvae were registered in Margaritifera dahurica pearl mussels from Komarovka river, a tributary of Razdolnaya River, on the territory of the Ussuriysky Nature Reserve. Bitterling larvae at diff erent stages of development were also found in Nodularia douglasiae mussels from Razdolnaya River.

First comparative assessment of contamination by plastics and non-synthetic particles in three bivalve species from an Italian sub-alpine lake

This study aimed to compare the contamination from plastics and non-synthetic particles in the three freshwater bivalve mollusks Unio elongatulus, (native) and Corbicula fluminea and Dreissena polymorpha (invasive), collected in Lake Maggiore, the second greatest Italian lake. Organisms were collected from eight sites located throughout the lake, during three years (2019–2021). The quali-quantitative characterization of particles has been carried out using a Fourier Transform Infrared Microscope System (μFT-IR). Results showed that both plastics and non-synthetic particles released in the water are taken up by bivalves, even though low intake-up to 6 particles/individuals-were measured for all the three species. Microfibers of both synthetic (polyester, polyamide) and natural (cellulose) origin represented the particles mostly ingested by bivalves. A significant decrease of particle loads was observed in 2020 with respect to 2019 and 2021, significantly different for D. polymorpha and U. elongatulus, suggesting a transient reduction of the particle release in the lake in this year. Our findings highlight the need to improve the understanding of the mechanisms of uptake and clearance of these contaminants by filter feeding organisms, and their adverse consequences in realistic environmental conditions.

Peculiarities of Unio tumidus and Unio Pictorum (Unionidae) Adaptive Reactions to the Water Temperature Increase in the Microcosm

The paper deals with adaptive reactions of the freshwater bivalve mollusks of the family Unionidae under water temperature increase to the critical values in the model ecosystem - the microcosm. It was found that the water temperature increase resulted in changes of the metabolic processes, namely decrease of the total protein and glycogen content in gills of <i>Unio tumidus</i> and <i>U. pictorum.</i> Under critical temperatures (30±0.5°C), high activity of LDHase and decrease of K<sup>+</sup>/Na<sup>+</sup>-ATPase activity was registered, as well as increase of the filtration rate and oxygen consumption. Considerable need for oxygen was conditioned by oxidation of the energy substrates for instant production of energy for the adaptive processes. However, prolonged impact of increased temperature and thus high rate of metabolic processes in the mollusks can result in exhaustion of the energy resources available for key biological processes, such as growth and reproduction. These results confirmed that over the water temperatures rise owing to the global climate change, many populations of the freshwater bivalves can appear dangerously close to the upper limit of the thermal tolerance.

Seasonal Changes in Biochemical Composition of Freshwater Bivalve Mollusc Lamellidens marginalis (Lamark) from Purna River Near Jafrabad (M.S.) India

Seasonal Changes in Biochemical Composition of Freshwater Bivalve Mollusc Lamellidens marginalis (Lamark) from Purna River Near Jafrabad (M.S.) India

A global synthesis of ecosystem services provided and disrupted by freshwater bivalve molluscs.

ABSTRACTIdentification of ecosystem services, i.e. the contributions that ecosystems make to human well‐being, has proven instrumental in galvanising public and political support for safeguarding biodiversity and its benefits to people. Here we synthesise the global evidence on ecosystem services provided and disrupted by freshwater bivalves, a heterogenous group of >1200 species, including some of the most threatened (in Unionida) and invasive (e.g. Dreissena polymorpha) taxa globally. Our systematic literature review resulted in a data set of 904 records from 69 countries relating to 24 classes of provisioning (N = 189), cultural (N = 491) and regulating (N = 224) services following the Common International Classification of Ecosystem Services (CICES). Prominent ecosystem services included (i) the provisioning of food, materials and medicinal products, (ii) knowledge acquisition (e.g. on water quality, past environments and historical societies), ornamental and other cultural contributions, and (iii) the filtration, sequestration, storage and/or transformation of biological and physico‐chemical water properties. About 9% of records provided evidence for the disruption rather than provision of ecosystem services. Synergies and trade‐offs of ecosystem services were observed. For instance, water filtration by freshwater bivalves can be beneficial for the cultural service ‘biomonitoring’, while negatively or positively affecting food consumption or human recreation. Our evidence base spanned a total of 91 genera and 191 species, dominated by Unionida (55% of records, 76% of species), Veneroida (21 and 9%, respectively; mainly Corbicula spp.) and Myoida (20 and 4%, respectively; mainly Dreissena spp.). About one third of records, predominantly from Europe and the Americas, related to species that were non‐native to the country of study. The majority of records originated from Asia (35%), with available evidence for 23 CICES classes, as well as Europe (29%) and North America (23%), where research was largely focused on ‘biomonitoring’. Whilst the earliest record (from 1949) originated from North America, since 2000, annual output of records has increased rapidly in Asia and Europe. Future research should focus on filling gaps in knowledge in lesser‐studied regions, including Africa and South America, and should look to provide a quantitative valuation of the socio‐economic costs and benefits of ecosystem services shaped by freshwater bivalves.

Evaluation of interactive effects of phosphorus-32 and copper on marine and freshwater bivalve mollusks

Purpose Contaminants seldom occur in isolation in the aquatic environment. While pollution of coastal and inland water bodies has received considerable attention to date, there is limited information on potential interactive effects between radionuclides and metals. Whether by accidental or controlled release, such contaminants co-exist in aquatic ecosystems and can pose an enhanced threat to biota. Using a range of biological responses, the study aimed to evaluate relative interactive effects on representative freshwater and marine bivalve species. Methods An integrated, multi-biomarker approach was adopted to investigate response to copper (Cu, 18 μg L−1), a known environmentally relevant genotoxic metal and differing concentrations of phosphorus-32 (32P; 0.1 and 1 mGy d−1), alone and in combination in marine (Mytilus galloprovincialis) and freshwater (Dreissena polymorpha) mussels. Genetic and molecular biomarkers were determined post-exposure and included DNA damage (as measured by the comet assay), micronuclei (MN) formation, γ-H2AX foci induction and the expression of key stress-related genes (i.e. hsp70/90, sod, cat, gst). Results Overall, using a tissue-specific (i.e. gill and digestive gland) approach, genotoxic response was reflective of exposures where Cu had a slight additive effect on 32P-induced damage across the species (but not all), cell types and dose rates. Multivariate analysis found significant correlations between comet and γ-H2AX assays, across both the tissues. Transcriptional expression of selected genes were generally unaltered in response to contaminant exposures, independent of species or tissues. Conclusions Our study is the first to explore the interactive effects of ionizing radiation (IR) and Cu on two bivalve species representing two ecological habitats. The complexity of IR-metal interactions demonstrate that extrapolation of findings obtained from single stressor studies into field conditions could be misrepresentative of real-world environments. In turn, environmental protective strategies deemed suitable in protecting biota from a single, isolated stressor may not be wholly adequate.

Global Crystallographic Texture of Freshwater Bivalve Mollusks of the Unionidae Family from Eastern Europe Studied by Neutron Diffraction.

The crystallographic texture of the whole valves of bivalve mollusks from the family Unionidae Unio pictorum Linnaeus, 1758 and Anodonta cygnea Linnaeus, 1758 is studied using pole figures measured using neutron diffraction. The use of neutron diffraction, in contrast to X-rays, makes it possible to study the valves without destroying them. Thus, we can discuss the study of the global texture of the entire valve. It was revealed that the pole figures of aragonite in the valves repeat their shape. The pole density maxima for U. pictorum from the Danube Delta and the Gulf of Finland in the Baltic Sea, living at different salinities and temperatures, differs by 0.41 mrd. The maximum value of the crystallographic texture for A. cygnea from the Danube Delta was also measured (5.07 mrd). In terms of texture sharpness, it surpasses the shell of marine bivalve mollusks, which are partially or completely composed of aragonite. Although U. pictorum and Mya arenaria Linnaeus, 1758 have different microstructures, their pole figures are very similar in isolines pattern, but differ in pole density maxima. No relationship was found between the crystallographic texture and the microstructure in U. pictorum. In addition, we report good qualitative agreement between aragonite X-ray pole figures of Sinanodonta woodiana Lea, 1834 from the Czech river Luznice, and neutron pole figures of U. pictorum from the Danube Delta.

First Immunodetection of Sensory and Nervous Systems of Parasitic Larvae (Glochidia) of Freshwater Bivalve Nodularia douglasiae.

Most freshwater mussels have an unusual life cycle that requires host fish species for larval (glochidia) development and dispersal. Glochidia have a unique morphological structure that adapts to parasitic lifestyles and survival. The morphology of the glochidial shells of most Unionoidea, a group of freshwater bivalve mollusks, has been studied in detail using light and scanning electron microscopy. This study summarizes our data on the glochidia shell morphology of the Asian mussel Nodularia douglasiae from two localities in the Primorsky Territory, the Russian Far East. In contrast to the shell morphology of glochidia, little is known about the neurodevelopment of the Unionoidea. Herein, we first demonstrate that the structures of the sensory, muscle, and nervous systems of the glochidia larvae of N. douglasiae differ dramatically from those of the comparable larval systems of marine bivalve species, as revealed through alpha-acetylated tubulin, serotonin (5-HT), and FMRFamide antibodies as well as phalloidin for detection of F-actin and whole-mount confocal microscopy. We found that the glochidia sensory system included four pairs of tubulin-lir multicilia hair cells. Non-ciliar tubulin-lir cells synthesize the neuropeptide FMRFamide and are identified as afferent neurons collecting information from peripheral tubulin-lir hair sensory cells to nervous regulators. The glochidia’s muscular system was represented by a smooth adductor, retractors, and minor muscle bundles associated with the shell and visceral organs. The 5-HT-lir larval system is arranged most simply and consists of two immunopositive neurons innervating the adductor. The FMRFamide-lir system is more complicated and consists of several neuronal centers comprising neuronal bodies and their neurites in different areas of the larva. The FMRFamide-lir neurons are closely associated with sensory hair cells, and others, together with 5-HT-lir neurons, may be involved in the anlagen of adult ganglia. Thus, the nervous system of N. douglasiae glochidia is drastically different from other mollusks and lophotrochozoans because of the absence of an apical organ and the location and composition of FMRFamide and 5-HT cells. Morphological, molecular, and behavioral investigations of Unionoidea taxa need to be further conducted to investigate the parasite-host relationship, nerve-dependent regulation of parasite behavior, and evolution of mollusks.

Ultrastructure of the gill ciliary epithelium of Limnoperna fortunei (Dunker 1857), the invasive golden mussel

BackgroundLimnoperna fortunei is a freshwater bivalve mollusc originally from southern Asia that invaded South America in the 1990’s. Due to its highly efficient water pumping and filtering, and its capacity to form strong adhesions to a variety of substrates by byssus thread, this invasive species has been able to adapt to several environments across South America, causing significant ecological and economic damages. By gaining a deeper understanding of the biological and ecological aspects of L. fortunei we will be able to establish more effective strategies to manage its invasion. The gills of the mollusc are key structures responsible for several biological functions, including respiration and feeding. In this work, we characterized the ultrastructure of L. fortunei gills and its ciliary epithelium using light microscopy, transmission and scanning electron microscopies. This is the first report of the morphology of the epithelial cells and cilia of the gill of L. fortunei visualized in high resolution.ResultsThe analysis showed highly organized and abundant ciliary structures (lateral cilia, laterofrontal cirri and frontal cilia) on the entire length of the branchial epithelium. Mitochondria, smooth endoplasmic reticulum and glycogen granules were abundantly found in the epithelial cells of the gills, demonstrating the energy-demanding function of these structures. Neutral mucopolysaccharides (low viscosity mucus) were observed on the frontal surface of the gill filaments and acid mucopolysaccharides (high viscosity mucus) were observed to be spread out, mainly on the lateral tract. Spherical vesicles, possibly containing mucus, could also be observed in these cells. These findings demonstrate the importance of the mucociliary processes in particle capture and selection.ConclusionsOur data suggest that the mechanism used by this mollusc for particle capture and selection could contribute to a better understanding of key aspects of invasion and also in the establishment of more efficient and economically viable strategies of population control.

Accumulation of microplastics in the bivalve mollusc Unio tumidus under experimental and field exposures

Background. An increased production and widespread use of plastics have made microplastic (MP) pollution a serious environmental problem. Most of MP found in the marine environment comes from rivers, however, the freshwater pollution by MP is less studied. Filter-feeding organisms, like bivalve molluscs, are the primary target orga­nisms for MP. Nevertheless, the studies of MP accumulation in the bivalves mainly focus on the marine species and depend on expensive equipment. The goal of this study was to detect the presence of MP in the body of freshwater bivalve mollusc Unio tumidus from a typical field site in Western Ukraine and under laboratory sub-chronic exposure to microplastic at a typical concentration for freshwater. Materials and Methods. For the study, we exposed molluscs to waterborne MP (0.1–0.5 mm) in the concentration of 1.0 mg L-1 corresponding to ~850 items L-1 for 14 days and analysed the concentration of MP in the soft tissues and water every two days. The molluscs and water from the field site, confirmed as polluted one, were also analysed. To estimate the number of MP particles, we used a modified method based on the cleavage of biological materials with potassium hydroxide and hydrogen peroxide and microscopic analysis of MP after the staining with fluorescent Nile Red dye. Results. The MP concentration in the soft tissues of the specimens from the refe­rence site was 9.5 items per soft body and demonstrated a bell-shaped response curve throughout the 14-days exposure with maximum of 327.0 items per body on the 10th day and a negative correlation with the concentration of MP in the experimental tank that changed within the range of 590–790 items L-1. The level of MP in the field specimens from the polluted area was 76.5 items per body, and in the water, it was about 103 items L-1. The maximum MP abundance factor, calculated as CFi = Ci/C0 (utilising the value 9.5 as C0), was 83.18 and 8.05 for 10 days of exposure and field specimens, correspondingly. Conclusion. These data indicate the high accumulative ability of U. tumidus towards microplastics and draw attention to the utilizing of this species for the biomonitoring of microplastics pollution and depuration of surface waters from it.

Shifted mineral ions transport in the mollusk Unio pictorum exposed to environmental concentrations of diclofenac

Previous studies showed that diclofenac (DCF), when released in the environment, can be toxic to aquatic animals (fish and mollusks), affecting gills, which are the main organ of ionic regulation. This study focuses on detecting the effects of relevant environmental concentrations of DCF (0.1–1 μg L−1) on the transport of main mineral cations, i.e. sodium (Na), potassium (K), calcium (Ca), and magnesium (Mg), by widely distributed freshwater bivalve mollusks Unio pictorum. After 96-h exposure to river aerated water at 25 °C with DCF concentrations of 0 (control), 0.1 (treatment I), and 1 μg L−1 (treatment II), the mollusks were transferred to deionized water, and daily (for 7 days) concentrations of these cations in the medium have been measured. Animals exposed to 1 μg L−1 DCF maintained the ionic balance between the organism and the diluted medium at a significantly higher level of Na, K, and Mg ions in water compared to the control and animals exposed to 0.1 μg L−1 DCF. At 0.1 μg L−1 DCF, the greater loss concerning the control (p < 0.05) was found only for Na ion. There were no differences in the dynamics of Ca ions between control and both treatments. This study showed that detectable environmental concentrations of DCF in natural waters can influence the transport of main cations required by freshwater animals to maintain their ionic balance, and the observed effect (elevated ion loss) is ion-specific and also dose-dependent.

Operativnyy analiz stvorochnoy aktivnosti mollyuskov v avtomatizirovannykh sistemakh ekologicheskogo biomonitoringa

The article describes features of the operational analysis of valve activity of freshwater (Unio pictorum) and marine (Black Sea mussel Mytilus galloprovincialis) bivalve molluscs for created automated systems of bioelectronic environmental control. The studies used measuring data obtained from long-term field and laboratory experiments using instruments developed by the author. The assessment of the mollusc general behavioral characteristics expressed in the dynamics and amplitude of group valve activity as a response to various effects made it possible to determine typical behavioral response models of toxic effects in the aquatic control environment. For the operational analysis, the main statistical indicators are identified, which are used to create software algorithms for automatic decision-making of the environmental biomonitoring system. As these indicators are used first of all the group time-sliding estimates of the synchronism of mollusc reactions, the data of valve activity averaged in different time intervals and the gape level (group and individual). The existence of established models, specified calculated numerical indicators and their permissible limits will ensure the standardization of the approach to detection of toxic factors and further implementation of such biomonitoring systems at control points.

Why are so many Northern European aquatic invertebrates missing in red-listing and how can we improve assessments for those?

The biodiversity crisis is advancing rapidly. One tool to measure extinction risk is the Red List of Threatened Species which follows the IUCN evaluation criteria (International Union for Conservation of Nature). Many aquatic invertebrates in Northern Europe are completely missing a red listing process and are evaluated as Data Deficient (DD) or Not Evaluated (NE). In our project, we focus on marine crustaceans and freshwater molluscs (Bivalvia). A systematic survey of more than 440 crustacean and 44 molluscan species in 12 Northern European countries shows that while many freshwater bivalve molluscs and marine crustaceans have existing molecular barcodes as well as digital occurrence records in databases (e.g. in GBIF, the Global Biodiversity Information Facility), there exists no evaluation process or regular monitoring for those species and their population status. With such a high level of non-evaluation of species status, species action plans (for single species or multi-taxon approaches) are far away from reality. In general, traditional monitoring methods based on observational surveys are known to be inefficient, costly and time consuming. e-DNA allows us to detect species with a high level of sensitivity as long as those assays are well validated. Molecular occurrence records can be used to detect rare species and to collect population information. In our Swedish project, we are metabarcoding sediment and plankton samples using metazoan and taxon-specific primers to detect threatened aquatic species. During 2019 and 2020, we collected samples at 15 localities in two marine protected areas for marine crustaceans and at 15 different localities for freshwater molluscs at the Swedish west coast. At each location plankton, sediment and traditional aquatic monitoring samples were taken. The idea is to compare how the methods perform in finding rare species, which could improve the data for those groups so they can be evaluated in the next round of red listing (2025) in Sweden. During the entire project, there is an on-going dialogue with stakeholders and experts from the Swedish Species Information Centre, responsible for the red listing process in the country.

Evolutionary insights on a novel mussel-specific foot protein-3α gene family

Silky byssus threads enable a number of marine and freshwater bivalve mollusks to attach themselves to hard substrates. Byssus production is an energy-costly process, which accompany the switch from planktonic to sessile life. Pointing the attention to a small foot protein (fp-3α) first identified in Perna viridis and abundantly secreted during the bissogenesis, we report the presence of a fp-3α gene family in species of the Mytilus complex, byssogenic bivalve mollusks mostly inhabiting marine waters. In the genome of Mytilus galloprovincialis we identified twelve fp-3α genes showing differences in exon-intron organization and suggesting that, as in the case of arthropod and mollusk defensins, exon shuffling could have played an important role in the evolution of this gene family. Also, the different tissue expression patterns of these mussel genes support their functional diversification. All predicted fp-3α proteins curiously possess a Csαβ three-dimensional motif based on 10 highly conserved cysteines and exhibit structural similarity to invertebrate defensins. The role of these small cysteine-rich proteins in supporting the byssus-mediated mussel adhesion or their action as host defence peptides remains to be established with further study.

Effect of Monsoon Climate in Accurate Size of Histological Variations in Gonads of Freshwater Bivalve Mollusc Corbicula regularis

Effect of Monsoon Climate in Accurate Size of Histological Variations in Gonads of Freshwater Bivalve Mollusc Corbicula regularis

Biomarkers of Oxidative Stress in Freshwater Bivalve Mollusks (Review)

An analysis of published data and data of our own on the features of using biomarkers of oxidative stress in bivalve mollusks for ecotoxicological studies of fresh waters is presented. Various protective mechanisms of the antioxidant system in Bivalvia in response to the action of organic contaminants and heavy metals are described. Several examples of the use of bivalve mollusks as a biological model in freshwater monitoring are considered. It is shown that the indices of oxidative stress of bivalve mollusks are informative markers of anthropogenic pollution.

Physiological and Metabolic Responses of Marine Mussels Exposed to Toxic Cyanobacteria Microcystis aeruginosa and Chrysosporum ovalisporum.

Toxic cyanobacterial blooms are a major contaminant in inland aquatic ecosystems. Furthermore, toxic blooms are carried downstream by rivers and waterways to estuarine and coastal ecosystems. Concerning marine and estuarine animal species, very little is known about how these species are affected by the exposure to freshwater cyanobacteria and cyanotoxins. So far, most of the knowledge has been gathered from freshwater bivalve molluscs. This work aimed to infer the sensitivity of the marine mussel Mytilus galloprovincialis to single as well as mixed toxic cyanobacterial cultures and the underlying molecular responses mediated by toxic cyanobacteria. For this purpose, a mussel exposure experiment was outlined with two toxic cyanobacteria species, Microcystis aeruginosa and Chrysosporum ovalisporum at 1 × 105 cells/mL, resembling a natural cyanobacteria bloom. The estimated amount of toxins produced by M. aeruginosa and C. ovalisporum were respectively 0.023 pg/cell of microcystin-LR (MC-LR) and 7.854 pg/cell of cylindrospermopsin (CYN). After 15 days of exposure to single and mixed cyanobacteria, a depuration phase followed, during which mussels were fed only non-toxic microalga Parachlorella kessleri. The results showed that the marine mussel is able to filter toxic cyanobacteria at a rate equal or higher than the non-toxic microalga P. kessleri. Filtration rates observed after 15 days of feeding toxic microalgae were 1773.04 mL/ind.h (for M. aeruginosa), 2151.83 mL/ind.h (for C. ovalisporum), 1673.29 mL/ind.h (for the mixture of the 2 cyanobacteria) and 2539.25 mL/ind.h (for the non-toxic P. kessleri). Filtering toxic microalgae in combination resulted in the accumulation of 14.17 ng/g dw MC-LR and 92.08 ng/g dw CYN. Other physiological and biochemical endpoints (dry weight, byssus production, total protein and glycogen) measured in this work did not change significantly in the groups exposed to toxic cyanobacteria with regard to control group, suggesting that mussels were not affected with the toxic microalgae. Nevertheless, proteomics revealed changes in metabolism of mussels related to diet, specially evident in those fed on combined cyanobacteria. Changes in metabolic pathways related with protein folding and stabilization, cytoskeleton structure, and gene transcription/translation were observed after exposure and feeding toxic cyanobacteria. These changes occur in vital metabolic processes and may contribute to protect mussels from toxic effects of the toxins MC-LR and CYN.