Great Pond Snail Lymnaea Stagnalis Research Articles

Dominant gingers – Discovery and inheritance of a new shell polymorphism in the great pond snail Lymnaea stagnalis

AbstractColor polymorphism is a classic study system for evolutionary genetics. One of the most color‐polymorphic animal taxa is mollusks, but the investigation of the genetic basis of color determination is often hindered by their life history and the limited availability of genetic resources. Here, we report on the discovery of shell color polymorphism in a much‐used model species, the great pond snail Lymnaea stagnalis. While their shell is usually beige, some individuals from a Greek population show a distinct red shell color, which we nicknamed Ginger. Moreover, we found that the inheritance fits simple, single‐locus Mendelian inheritance with dominance of the Ginger allele. We also compared crucial life‐history traits between Ginger and wild‐type individuals, and found no differences between morphs. We conclude that the relative simplicity of this polymorphism will provide new opportunities for a deeper understanding of the genetic basis of shell color polymorphism and its evolutionary origin.

A novel and unique refraction-based optical recording system for pharmacological investigations on isolated muscle preparations

In the field of neuroscience and ecotoxicology, there is a great need for investigating the effect(s) of a variety of different chemicals (e.g., pharmacologically active compounds, pesticides, neurotransmitters, modulators) at different biological levels. Different contractile tissue preparations have provided excellent model systems for in vitro pharmacological experiments for a long time. However, such investigations usually apply mechanical force transducer-based approaches. Thus, a rapid, easy, cheap, digital, and reproducible in vitro pharmacological method based on an effective, ‘non-invasive’ (compared to the force-transducer approaches), refraction-based optical recording approach and isolated heart preparations was developed.•A versatile and unique refraction-based optical recording system with a Java application was developed.•The recording system was tested and validated on isolated heart preparations obtained from the widely used invertebrate model organism, the great pond snail (Lymnaea stagnalis).•The recording system illustrates the progression of technology from the mechanical force transducer system and can represent a suitable tool in ecotoxicology or neuroscience.

Ключові види тварин в екосистемах заходу України

The attention in the article is paid to the key species research importance. Their classification was discussed in our article published in “Studia Biologica” (Y. Tsaryk, O. Reshetylo, I. Tsaryk, Biol. Stud. 2019: 13(1); 161–168). The main emphasis was made on ecological key species, while other categories were analyzed as well (protective, social etc.). A row of potential key species in different ecosystems was proposed based on the original field research. So, such phytophagous insects like the alder leaf beetles Agelastica alni, Linaeidea aenea, and the mother of pearl moth Patania ruralis are proposed to be the key species in forest ecosystems. Altogether in terrestrial ecosystems such species as the common carder bee Bombus pascuorum and the buff-tailed bumblebee B. terrestris are tend to be the key species among the pollinators (excluding European honey bee Apis mellifera). Ants are important invertebrate key species as well: Formica – in forest ecosystems, Lasius, Myrmica and Tetramorium – shrub and meadow ones. Almost the same we can say about some species of amphibians (the common toad Bufo bufo, the common frog Rana temporaria, and the edible frog Pelophylax esculentus). Eurasian jay Garrulus glandarius, the great tit Parus major, and woodpeckers, the great spotted woodpecker Dendrocopos major in particular, are among the birds’ key species on our minds. European otter Lutra lutra is the possible key species in freshwater ecosystems. Zooplankton as a whole community might be considered a key “species” too. The great pond snail Lymnaea stagnalis is the key species among freshwater mollusks. The fish of Barbatula, Cobitis, Sabanejewia, Misgurnus genera, and Eudontomyzon representatives are the key species in streams and rivers. European beaver Castor fiber, European otter L. lutra, the white stork Ciconia ciconia, and reed warblers are thought to be the key species in semiaquatic ecosystems. The presented data about the key species need further research on their population and consortive organizations, as well as their functional role in the support of ecosystem stability under the environmental stochasticity, has to be clarified.

Combined impact of toxicants and helminths on great pond snail (Lymnaea stagnalis L.) homeostasis stability

Anthropogenic pressure on the hydrosphere has led to the progressive increase in its pollution by various components of both industrial and domestic effluents. The surfactants, which are the components of synthetic detergents, are among the most dangerous for aquatic organisms. The effect of different concentrations of detergent “Ushastyi nian” produced by “Vinnytsiapobutkhim” was studied in concentrations of 2.5, 5, 10, 20, 40 mg/dm3 on a number of physic-chemical parameters of the homeostasis of haemolymph of Lymnaea stagnalis (Linnaeus, 1758). The investigated great pond snails were intact or infected with various life cycle stages (maternal and daughter redia, cercariae) of the trematode Echinoparyphium aconiatum Dietz, 1909. The studied material includes 315 individuals of mollusсs collected by hand in the reservoirs of the drainage and reclamation system in the basin of the Teteriv River (right-bank tributary of the Middle Dnieper river) in Central Polissya (Zatyshshia village, Zhytomyr Region). The toxicological experiment was conducted by standard scheme according to (Alekseev, 1981). It was preceded by a mandatory (Khlebovich, 1981) 15-day acclimation of animals intended for toxicological examination to aquarium conditions (volume of aquaria 20 l, density of molluscs 3–4 individuals/l, water temperature 20–22 °C, pH 7.9–8.4, oxygenation 8.1 to 8.5 mg O2/dm3). The presence of molluscs in toxic environments was accompanied by the development of a responsive reaction such as poisoning. The most obvious symptoms were quantitative changes in the values of physic-chemical parameters of their haemolymph, which largely ensure its homeostasis. These parameters include the total protein level, the specific gravity, and pH. In these molluscs, about 90 % of the total haemolymph protein is represen­ted by haemocyanin. It determines, due to its powerful buffering properties, both the level of oxygen capacity and water-osmotic pressure in the body of molluscs. The pathological process, which develops as a result of combined toxicant and helminthic invasion impact on L. stagnalis expresses more clear, quick and higher toxicant concentration, helminthic invasion intensity and durability level of different lifecycle stages of trematodes. The experimental molluscs defend themselves against the affected values of the mentioned indicators of stability of homeostasis by the set of inherent protective and adaptive reactions (rapid behavioral, physiological and biochemical ones). They aimed at maintaining the viability of individuals. The effectiveness of protective and adaptive reactions in trematode-infected molluscs was significantly lower compared to non-infected individuals. The degree of cumulative damaging effect of the toxicant and parasites was determined not only by the concentration of surfactants. To a large extent it depended on both the rate of the infection and the stage of the life cycle of parasites. The pathogenic effect of the latter on their mollusc hosts decreased as follows: “old” (maternal) redia > “young” (daughter) redia > cercariae.

A lysine residue from an extracellular turret switches the ion preference in a Cav3 T-Type channel from calcium to sodium ions

Cav3 T-type calcium channels from great pond snail Lymnaea stagnalis have a selectivity-filter ring of five acidic residues, EE(D)DD. Splice variants with exons 12b or 12a spanning the extracellular loop between the outer helix IIS5 and membrane-descending pore helix IIP1 (IIS5-P1) in Domain II of the pore module possess calcium selectivity or dominant sodium permeability, respectively. Here, we use AlphaFold2 neural network software to predict that a lysine residue in exon 12a is salt-bridged to the aspartate residue immediately C terminal to the second-domain glutamate in the selectivity filter. Exon 12b has a similar folding but with an alanine residue in place of lysine in exon 12a. We express LCav3 channels with mutated exons Ala-12b-Lys and Lys-12a-Ala and demonstrate that they switch the ion preference to high sodium permeability and calcium selectivity, respectively. We propose that in the calcium-selective variants, a calcium ion chelated between Domain II selectivity-filter glutamate and aspartate is knocked-out by the incoming calcium ion in the process of calcium permeation, whereas sodium ions are repelled. The aspartate is neutralized by the lysine residue in the sodium-permeant variants, allowing for sodium permeation through the selectivity-filter ring of four negatively charged residues akin to the prokaryotic sodium channels with four glutamates in the selectivity filter. The evolutionary adaptation in invertebrate LCav3 channels highlight the involvement of a key, ubiquitous aspartate, "a calcium beacon" of sorts in the outer pore of Domain II, as determinative for the calcium ion preference over sodium ions through eukaryotic Cav1, Cav2, and Cav3 channels.

Sublethal cadmium exposure in the freshwater snail Lymnaea stagnalis meets a deficient, poorly responsive metallothionein system while evoking oxidative and cellular stress

The Great Pond snail Lymnaea stagnalis (Gastropoda, Hygrophila) is a wide-spread freshwater gastropod, being considered as a model organism for research in many fields of biology, including ecotoxicology. The aim of the present study was to explore the Cd sensitivity of L. stagnalis through the measurement of a biomarker battery for oxidative, toxic and cellular stress. The interpretation of biomarker parameters occurred against the background of a truncated metallothionein protein with a limited Cd-binding capacity. Individuals of L. stagnalis were exposed through 14 days to uncontaminated water (controls) or to low (30 μg · L−1) or high (50 μg · L−1) Cd concentrations. The digestive gland of control and low-Cd exposed snails was processed for transcriptional analysis of the Metallothionein (MT) gene expression, and for determination of biomarkers for oxidative stress, toxicity and cellular stress. Digestive gland supernatants of high-Cd exposed snails were subjected to chromatography and subsequent analysis by spectrophotometry. It was shown that the MT system of L. stagnalis is functionally deficient, with a poor Cd responsiveness at both, the transcriptional and the protein expression levels. Instead, L. stagnalis appears to rely on alternative detoxification mechanisms such as Cd binding by phytochelatins and metal inactivation by compartmentalization within the lysosomal system. In spite of this, however, traces of Cd apparently leak out of the pre-determined detoxification pathways, leading to adverse effects, which is clearly indicated by biomarkers of oxidative and cellular stress.

The growth characteristics and survival rates of great pond snail (Lymnaea stagnalis L.) juvenile under the heavy metal impact

The study of the long-term effects of toxic substances, in particular, heavy metals, on aquatic organisms is currently a topical issue, due to the increase of anthropogenic pressure on the hydrosphere. The embryonic and juvenile stages of mollusks are more sensitive to toxic effects than adult ones. Consequently, the effects of different concentrations of heavy metal in the aquatic environment on the growth and survival rates of Lymnaea stagnalis juveniles were evaluated. In a chronic toxicological experiment, we used chronic lethal, sublethal, and subthreshold concentrations of heavy metals. We conducted 12 toxicological chronic experiments, lasting 60 days, with 1070 specimens of L. stagnalis juveniles. The toxic effect of heavy metals exposure in the aquatic environment in young individuals is manifested at much lower concentrations than in adults. The heavy metals ions affect the shell height of L. stagnalis juveniles even at the embryonic stage, which is manifested in some cases in the acceleration of their growth, in others – in its slowing down. The chronic experiment indicated that the values of shell height growth of juveniles in most cases correlate with the values of the total body weight growth. Under the influence of sublethal concentrations of heavy metal ions, the survival rates of juveniles are 3–4 times lower than the control. In solutions containing chronic lethal concentrations of Co2+ and Mn2+, up to 80–90% of juveniles die. The sharper and more rapid response of young snails to toxic effects compared to adult animals can be explained by embryo intoxication.

A combined bioinformatics and LC-MS-based approach for the development and benchmarking of a comprehensive database of Lymnaea CNS proteins.

Applications of key technologies in biomedical research, such as qRT-PCR or LC-MS-based proteomics, are generating large biological (-omics) datasets which are useful for the identification and quantification of biomarkers in any research area of interest. Genome, transcriptome and proteome databases are already available for a number of model organisms including vertebrates and invertebrates. However, there is insufficient information available for protein sequences of certain invertebrates, such as the great pond snail Lymnaea stagnalis, a model organism that has been used highly successfully in elucidating evolutionarily conserved mechanisms of memory function and dysfunction. Here, we used a bioinformatics approach to designing and benchmarking a comprehensive central nervous system (CNS) proteomics database (LymCNS-PDB) for the identification of proteins from the CNS of Lymnaea by LC-MS-based proteomics. LymCNS-PDB was created by using the Trinity TransDecoder bioinformatics tool to translate amino acid sequences from mRNA transcript assemblies obtained from a published Lymnaea transcriptomics database. The blast-style MMSeq2 software was used to match all translated sequences to UniProtKB sequences for molluscan proteins, including those from Lymnaea and other molluscs. LymCNS-PDB contains 9628 identified matched proteins that were benchmarked by performing LC-MS-based proteomics analysis with proteins isolated from the Lymnaea CNS. MS/MS analysis using the LymCNS-PDB database led to the identification of 3810 proteins. Only 982 proteins were identified by using a non-specific molluscan database. LymCNS-PDB provides a valuable tool that will enable us to perform quantitative proteomics analysis of protein interactomes involved in several CNS functions in Lymnaea, including learning and memory and age-related memory decline.

Cadmium impact on the growth and survival rate of great pond snail (Lymnaea stagnalis) in the chronic experiment

Cadmium impact on the growth and survival rate of great pond snail (Lymnaea stagnalis) in the chronic experiment

Neuronal Transcriptome Analysis of a Widely Recognised Molluscan Model Organism Highlights the Absence of Key Proteins Involved in the De Novo Synthesis and Receptor-Mediation of Sex Steroids in Vertebrates

Over the last ten years, the interpretation of the presence of vertebrate sex steroids in molluscs has changed dramatically. Evidence has been accumulating that CYP11A and CYP19A genes (encoding cholesterol side-chain cleavage enzyme and aromatase), that are crucial for the biosynthesis of sex steroids in vertebrates, as well as key functional sex steroid receptors, are missing in molluscan genomes. To provide further evidence, we sequenced the whole transcriptome of the central nervous system of the great pond snail (Lymnaea stagnalis) and screened it for sequences homologous to those used in the generally accepted vertebrate sex steroidogenesis pathway as well as the known sex steroid receptor-related genes (such as CYP11A, CYP19A, 3β-HSD, nPR, and nAR). Our screening confirmed the absence of several key sequences that are essential to accomplish a full sex steroid biosynthesis pathway similar to that of vertebrates. There was also no evidence for nuclear sex steroid receptors. Our findings support the contention that molluscan endocrinology differs from the well-characterized vertebrate endocrine system.

Functional characterization and related evolutionary implications of invertebrate gonadotropin-releasing hormone/corazonin in a well-established model species

In vertebrates, gonadotropin-releasing hormone (GnRH) peptide is the central mediator of reproduction. Homologous peptides have previously also been identified in molluscan species. However, emerging evidence suggests that these molecules might serve diverse regulatory functions and proposes to consider them as corazonin (CRZ). We previously isolated the full-length cDNA of the invGnRH/CRZ peptide (termed ly-GnRH/CRZ) in the well-established invertebrate model species, the great pond snail Lymnaea stagnalis; however, its predicted functions remain to be verified. In this study, we first confirmed the presence of the deduced active peptide from the central nervous system of L. stagnalis. Further, we performed in vivo and in vitro studies to explore the functions of ly-GnRH/CRZ. Injection of sexually mature specimens with synthetic active peptide had an inhibitory effect on locomotion and an acceleratory effect on egg-laying, but had no effect on feeding. The previously predicted modulatory effect of ly-GnRH/CRZ was supported by its identified co-localization with serotonin on the surface of the heart atria. Lastly, we demonstrated not only the presence of ly-GnRH/CRZ in the penial complex but also that ly-GnRH/CRZ-containing neurons project to the efferent penis nerve, suggesting ly-GnRH/CRZ may directly modulate the motor output of this peripheral tissue. Overall, our findings strongly support that ly-GnRH/CRZ is a multifunctional neuropeptide. These results contribute to the understanding of the GnRH superfamily and, more broadly, disciplines such as comparative endocrinology and neurobiology.

In the great pond snail (Lymnaea stagnalis), two stressors that individually enhance memory in combination block memory formation

Stress plays an important role in memory formation in the great pond snail (Lymnaea stagnalis (Linnaeus, 1758)). Individual stressors have been shown to enhance or to perturb long-term memory (LTM) formation. However, when snails perceive a combination of two stressors, it is unclear the outcome with regards to LTM formation. Here we first show that when L. stagnalis are exposed individually to either a predator stressor (crayfish effluent (CE), which is a kairomone) or a thermal stressor (30 °C), LTM formation is enhanced. In their natural environment, L. stagnalis may experience temperatures approaching 30 °C and they may encounter crayfish at the same time. How such a combination of stressors alters adaptive behaviour is unknown. Here we show that when these two stressors are combined, LTM formation is blocked. Since boiling CE inactivates the kairomone, we used previously boiled CE that we combined with the thermal stressor and found that LTM formation is again enhanced. These data show that (i) it cannot accurately be predicted how a combination of stressors when combined interact to alter LTM formation and (ii) there is a difference between hot CE and room temperature CE.

The Great Pond Snail (Lymnaea stagnalis) as a Model of Aging and Age-Related Memory Impairment: An Overview.

With the increase of life span, normal aging and age-related memory decline are affecting an increasing number of people; however, many aspects of these processes are still not fully understood. Although vertebrate models have provided considerable insights into the molecular and electrophysiological changes associated with brain aging, invertebrates, including the widely recognized molluscan model organism, the great pond snail (Lymnaea stagnalis), have proven to be extremely useful for studying mechanisms of aging at the level of identified individual neurons and well-defined circuits. Its numerically simpler nervous system, well-characterized life cycle, and relatively long life span make it an ideal organism to study age-related changes in the nervous system. Here, we provide an overview of age-related studies on L. stagnalis and showcase this species as a contemporary choice for modeling the molecular, cellular, circuit, and behavioral mechanisms of aging and age-related memory impairment.

Can Green Tea Alleviate the Effects of Stress Related to Learning and Long-Term Memory in the Great Pond Snail (Lymnaea stagnalis)?

Stress and anxiety have become more prevalent issues in recent years and teenagers are especially at high risk. Recent studies show that experiencing stress while learning can impair brain-cell communication, thus inhibiting learning. Green tea is believed to have the opposite effect, aiding in learning and memory retention. Lymnaea stagnalis is a pond snail with a simple nervous system and easily observable behaviors, making it an excellent model organism for human neurobiology. In this study, we used L. stagnalis to explore the relationship between green tea and a stressor that impairs memory formation to determine the effects of both green tea and stress on the snails’ ability to learn, form, and retain memories. Memory was assessed using a conditioning procedure known as conditioned taste aversion (CTA), where snails are exposed to a sweet substance followed by a bitter taste with the number of biting responses being recorded. For the CTA groups, a total of 33 snails in 3 separate cohorts (Control (i.e. no stress), stressed, and stressed with green tea) was used in the trainings. Our results indicated that the best learning and memory occurred in the combination stressed with green tea group, specifically for long-term memory, although snails displayed good learning and memory during the short-term and intermediate trials. Stress was shown to be harmful to snail learning and memory for short-term, intermediate, and long-term memory. Thus, green tea not only alleviated the effects of stress, but also improved the snails’ ability to learn and remember compared to their control counterparts (not stressed) group.

Progestogen-induced alterations and their ecological relevance in different embryonic and adult behaviours of an invertebrate model species, the great pond snail (Lymnaea stagnalis)

The presence of oral contraceptives (basically applying estrogens and/or progestogens) poses a challenge to animals living in aquatic ecosystems and reflects a rapidly growing concern worldwide. However, there is still a lack in knowledge about the behavioural effects induced by progestogens on the non-target species including molluscs. In the present study, environmental progestogen concentrations were summarised. Knowing this data, we exposed a well-established invertebrate model species, the great pond snail (Lymnaea stagnalis) to relevant equi-concentrations (1, 10, 100, and 500 ng L−1) of mixtures of four progestogens (progesterone, drospirenone, gestodene, levonorgestrel) for 21 days. Significant alterations were observed in the embryonic development time, heart rate, feeding, and gliding activities of the embryos as well as in the feeding and locomotion activity of the adult specimens. All of the mixtures accelerated the embryonic development time and the gliding activity. Furthermore, the 10, 100, and 500 ng L−1 mixtures increased the heart rate and feeding activity of the embryos. The 10, 100, and 500 ng L−1 mixtures affected the feeding activity as well as the 1, 10, and 100 ng L−1 mixtures influenced the locomotion of the adult specimens. The differences of these adult behaviours showed a biphasic response to the progestogen exposure; however, they changed approximately in the opposite way. In case of feeding activity, this dose-response phenomenon can be identified as a hormesis response. Based on the authors’ best knowledge, this is the first study to investigate the non-reproductive effects of progestogens occurring also in the environment on molluscan species. Our findings contribute to the global understanding of the effects of human progestogens, as these potential disruptors can influence the behavioural activities of non-target aquatic species. Future research should aim to understand the potential mechanisms (e.g., receptors, signal pathways) of progestogens induced behavioural alterations.

Identification, presence, and possible multifunctional regulatory role of invertebrate gonadotropin-releasing hormone/corazonin molecule in the great pond snail (Lymnaea stagnalis)

In the last years, our interpretation of the origin and function of the gonadotropin-releasing hormone (GnRH) neuropeptide superfamily has changed substantially. A main driver for these conceptual changes came from increased investigations into functions and evolutionary lineage of previously identified molluscan GnRH molecules. Emerging evidence suggests not only reproductive, but also diverse biological effects of these molecules and proposes they should most likely be called corazonin (CRZ). Clearly, a more global understanding requires further exploration of species-specific functions and structure of invGnRH/CRZ peptides. Towards this goal, we have identified the full-length cDNA of invGnRH/CRZ peptide in an invertebrate model species, the great pond snail Lymnaea stagnalis, termed ly-GnRH/CRZ, and characterized the transcript and peptide distribution in the central nervous system (CNS) and peripheral organs. Our results are consistent with previous data that molluscan GnRHs are more related to CRZs and serve diverse functions. Hence, our findings support the notion that peptides originally termed molluscan GnRH are multifunctional modulators and that nomenclature change should be taken into consideration.

Accumulation and histopathological effects of cadmium on the great pond snail Lymnaea stagnalis Linnaeus, 1758 (Gastropoda: Pulmonata)

Toxic metal ions are an important stress factor for a living organism. In this study, accumulation and histopathological changes in foot, mantle and hepatopancreas of great pond snail, Lymnaea stagnalis exposed to different Cadmium (Cd) concentrations in laboratory conditions were investigated. Great pond snails were exposed to sublethal concentrations of 7.92 μg/L, 15.85 μg/L, 31.7 μg/L and 63.4 μg/L Cd. At the end of 7, 14, 21 and 28 days, snail foot, mantle and hepatopancreas were removed to investigate and determine Cd accumulation and histopathological alterations by light microscopy. Cd levels determined in hepatopancreas were higher than those measured from the foot and the mantle of studied specimens. A positive correlation was found between Cd levels in tissues and exposure days. As a result of Cd application, we observed increase in the number of mucosit, pigment and protein cells and desquamation in the epithelium in the foot, atrophy in muscle fibrils, connective tissue cells and increase in the lipid vacuoles in the mantle, increase in the lipid vacuoles and amoebocyte in the hepatopancreas. The severity of the alterations resulting from Cd increased with dose-time dependent.

Accumulation of polybrominated diphenyl ethers and microbiome response in the great pond snail Lymnaea stagnalis with exposure to nylon (polyamide) microplastics

Microplastics attract widespread attention, including for their potential to transport toxic chemicals in the form of plasticisers and associated hydrophobic organic chemicals, such as polybrominated diphenyl ethers (PBDEs). The aims of this study were to investigate how nylon (polyamide) microplastics may affect PBDE accumulation in snails, and the acute effects of nylon particles and PBDEs on survival, weight change and inherent microbiome diversity and community composition of the pond snail Lymnaea stagnalis. Snails were exposed for 96 h to BDEs-47, 99, 100 and 153 in the presence and absence of 1% w/w nylon microplastics in quartz sand sediment. No mortality was observed over the exposure period. Snails not exposed to microplastics lost significantly more weight compared to those exposed to microplastics. Increasing PBDE concentration in the sediment resulted in an increased PBDE body burden in the snails, however microplastics did not significantly influence total PBDE uptake. Based on individual congeners, uptake of BDE 47 by snails was significantly reduced in the presence of microplastics. The diversity and composition of the snail microbiome was not significantly altered by the presence of PBDEs nor by the microplastics, singly or combined. Significant effects on a few individual operational taxonomic units (OTUs) occurred when comparing the highest PBDE concentration with the control treatment, but in the absence of microplastics only. Overall within these acute experiments, only subtle effects on weight loss and slight microbiome alterations occurred. These results therefore highlight that L. stagnalis are resilient to acute exposures to microplastics and PBDEs, and that microplastics are unlikely to influence HOC accumulation or the microbiome of this species over short timescales.

Using the Biotic Ligand Model framework to investigate binary metal interactions on the uptake of Ag, Cd, Cu, Ni, Pb and Zn in the freshwater snail Lymnaea stagnalis

There is growing interest in the development of mechanistically-based models, such as the Biotic Ligand Model (BLM), for assessing the environmental risk of metal mixtures. However, the derivation of such models requires insights into the mechanisms of multimetal interactions that are often lacking for aquatic organisms. In the present study, we investigated how binary mixtures of six metals (Ag, Cd, Cu, Ni, Pb and Zn) interact for uptake in the great pond snail Lymnaea stagnalis, a freshwater species particularly sensitive to metals in chronic exposure. For each metal, short-term (2–3 h) uptake experiments on juvenile snails were performed with the metal alone and in combination with a second metal, at concentrations encompassing the chronic toxicity concentration range. These experiments showed significant binary metal interactions for 7 out of 15 mixtures. Most interactions were inhibitory in nature, not reciprocal and caused by either Ag or Cu. They led to relative changes of uptake that did not exceed 50% within the range of metal chronic toxicity. The BLM proved to be successful at explaining most of the interactions, via competitive inhibition. This study is in support of using bioavailability-based models, such as the BLM, to model metal mixture interactions in L. stagnalis.

Simultaneous exposure to a pulsed and a prolonged anthropogenic stressor can alter consumer multifunctionality

Ecosystems face multiple anthropogenic threats globally, and the effects of these environmental stressors range from individual‐level organismal responses to altered system functioning. Understanding the combined effects of stressors on process rates mediated by individuals in ecosystems would greatly improve our ability to predict organismal multifunctionality (e.g. multiple consumer‐mediated functions). We conducted a laboratory experiment to test direct and indirect, as well as immediate and delayed effects of a heat wave (pulsed stress) and micropollutants (MPs) (prolonged stress) on individual consumers (the great pond snail Lymnaea stagnalis) and their multifunctionality (i.e. consumption of basal resources, growth, reproduction, nutrient excretion and organic‐matter cycling). We found that stressful conditions increased the process rates of multiple functions mediated by individual consumers. Specifically, the artificial heat wave increased process rates in the majority of the quantified functions (either directly or indirectly), whereas exposure to MPs increased consumption of basal resources which led to increases in the release of nutrients and fine particulate organic matter. Moreover, snails exposed to a heat wave showed decreased reproduction and nutrient excretion after the heat‐wave, indicating the potential for ecologically relevant delayed effects. Our study indicates that the immediate and delayed effects of stressors on individual organisms may directly and indirectly impact multiple ecosystem functions. In particular, delayed effects of environmental stress on individual consumers may cumulatively impede recovery due to decreased functioning following a perturbation. Reconciling these results with studies incorporating responses at higher levels of biological complexity will enhance our ability to forecast how individual responses upscale to ecosystem multifunctionality.