Riparius Meigen Research Articles

Beneath the surface: Decoding the impact of Chironomus riparius bioturbation on microplastic dispersion in sedimentary matrix

A detailed understanding of microplastics (MPs) behaviour in freshwater ecosystems is crucial for a proper ecological assessment. This includes the identification of significant transport pathways and net accumulation zones, considering their inherent, and already proven influence on aquatic ecosystems. Bioavailability of toxic agents is significantly influenced by macroinvertebrates' behaviour, such as bioturbation and burrowing, and their prior exposure history. This study investigates the effect of bioturbation activity of Chironomus riparius Meigen, 1804 on the vertical transfer of polyethylene MPs ex-situ. The experimental setup exposes larvae to a scenario of 10× the environmentally relevant high concentration of MPs (80 g m−2). Bioturbation activity was estimated using sediment profile imaging with luminophore tracers. This study demonstrated that spherical MPs are vertically transferred in the sediment due to the bioturbation activity of C. riparius larvae and that their presence influences the intensity of the bioturbation activity over time. The present findings provide a noteworthy contribution to the understanding of the relationship between ecosystem engineers and the dispersion and accumulation of MPs within freshwater ecosystems.

Community characteristics of macroinvertebrates and ecosystem health assessment in Qin River, a main tributary of the Yellow River in China.

To know well the ecosystem health status of Qin River, a main tributary of the Yellow River and the largest river in Jincheng region, macroinvertebrates from 49 sampling sites in the Qin River and its largest tributary, the Dan River, were investigated, and community characteristics were analyzed in the autumn of 2020; a Benthic index of Biotic Integrity (B-IBI) was established based on four metrics by a series of steps. The results showed that a total of 38 species of macroinvertebrates were collected and identified, belonging to 6 orders and 19 families, consisting of 17 Insecta species, 13 Gastropoda species, and 4 Oligochaeta species. Four species in Insecta belonged to EPT (E, Ephemeroptera; P, Plecoptera; T, Trichoptera); 10 species in Insecta belonged to Chironomidae and Tipulidae families. All species in Gastropoda belonged to Basematophora order, and, especially, Bellamya aeruginosa is highly tolerant to nutrients. All species in Oligochaetes belonged to Tubificidae family, which indicates eutrophication and low-dissolved oxygen. The dominant species in the study were Ephemera orientalis, Chironomus riparius Meigen, and Limnodrilus claparedianus. The final B-IBI scores varied from 0.75 to 3.75, with 5 sites in "excellent," 10 sites in "good," 10 sites in "normal" status, 12 sites in "poor" status, 12 sites in "very poor." "Very poor" and "poor" sites were mainly located in the middle reach of the Qin River and upper-middle reach of the Dan River in Jincheng region. B-IBI strongly differentiated the reference sites and impaired sites, suggesting the suitability of the B-IBI in the Qin River basin. Significantly negative correlations between NH4+-N, TN, and B-IBI indicated the B-IBI characterized well the influence of nitrogen pollution.

Study of seasonal distribution of chironominae (Chironomidae: Diptera) in Al- Battar river north Al Kut city / Iraq.

The influence of physical and chemical parameters on the abundance and diversity of subfamily Chironominae(Chironomidae: Diptera) in Al-Battar river north Al-kut city was studied over a period of eight months(Septemper 2012- April 2013) . Eight species of Chironominae were identified Chironomus plumosus (Linnaeus) was the most dominant made up 42.5% ,Chironomus sp. 17.8% ,Einfeldia sp. 13.6%, Chironomus riparius Meigen 10.3%,Chironomus staegeri Lundbeck 10.3%, Lauterborniella sp. 2.6% ,Parachironomus sp. 1.4% and Parachironomus hirtalatus(Beck & Beck) 1.1%. The results of this study showed that were significant correlations between the species and several environmental parameters.C. plumosus, C.staegeri, C.riparius and Einfeldia sp. this group showed significantly positive correlation ( p<0.01 and 0.05) with water depth and NH4-N and showed significantly negative correlation( p<0.01 and 0.05) with water turbidity. Also this group showed negative correlation but not significant with water temperature and NO3-N. C.plumosus showed positive correlation but non significantly with (pH, EC,TDS and NaCL) and showed no significant negative correlation with DO. One species Parachironomus sp. showed significant positive correlation with pH, EC, TDS and NaCL and this species recorded only in September. Parachironomus hirtalatus showed significant negative correlation with water depth and NO3-N. Lauterborniella sp. showed significant positive correlation with dissolved oxygen. Also showed positive correlation but non significantly with temperature, NO3-N, NH4-N, EC, TDS and NaCL and negative correlation but non significantly with pH, turbidity and water depth .Chironomus sp. showed positive and negative correlation but non significantly with ecological factors, so showed positive correlation with EC, TDS, NaCL, water depth and temperature. This species showed negative correlation with pH, DO, turbidity, NO3-N and NH4-N.

Accumulation of polychlorinated biphenyls (PCB) associated with bottom sediments in larvae of Chironomus riparius Meigen

Patterns of bioaccumulation of polychlorinated biphenyls (PCBs) by chironomid larvae (Chironomus riparius Meigen) were studied under laboratory conditions. Larvae were maintained for 20 days, separately in two batches of natural bottom sediments sampled from Rybinsk Reservoir (Russia), each differing in PCB content (425.6 μg / kg or 24.8 μg / kg dry weight, respectively). The study revealed that chironomid larvae accumulated PCBs at levels comparable to the PCB content measured in sediments from each exposure. The bioaccumulation coefficient (1.11 and 1.59, respectively, as per dry weight for compared sediment batches) depended directly on the sum PCB content in sediments. At high sediment PCB content, the ratios of homologous groups of PCBs in larvae and sediment were identical and corresponded to the Aroclor 1254 congeners profile; at lower PCB content, pronounced differences were revealed. In larvae, the ratios of 3, 4, 5, and 6CB homologues were evenly distributed at levels of 20–34 %, while the 4CB homologues prevailed (47 %) in sediments. The content of the latter compounds in larvae was lower than in sediments, and higher for the other homologous groups. The study indicates selective bioaccumulation of various homologous groups of PCBs under conditions of low sediment PCB content.

Exposure to a microplastic mixture is altering the life traits and is causing deformities in the non-biting midge Chironomus riparius Meigen (1804)

The effect of microplastics (MP) exposure on the chironomid species Chironomus riparius Meigen, 1804 was investigated using the OECD sediment and water toxicity test. Chironomid larvae were exposed to an environmentally relevant low microplastics concentration (LC), a high microplastics concentration (HC) and a control (C). The LC was 0.007 g m−2 on the water surface + 2 g m−3 in the water column + 8 g m−2 in the sediment, and the HC was 10 X higher than this for each exposure. The size of the majority of the manufactured microplastic pellets varied between 20 and 100 μm. The MP mixture consisted of: polyethylene-terephtalate (PET), polystyrene (PS), polyvinyl-chloride (PVC) and polyamide (PA) in a ratio of 45%: 15%: 20%: 20%, respectively, for the sediment exposure; 100% polyethylene for the water column exposure; and 50% polyethylene: 50% polypropylene for the water surface exposure. Different endpoints were monitored, including morphological changes in the mandibles and mentums of 4th instar larvae, morphological changes in the wings, mortality, emergence ratio, and developmental time. A geometric morphometric analysis showed a tendency toward widening of the wings, elongation of the mentums and changing the shape of the mandibles in specimens exposed to both concentrations of microplastics. The development time of C. riparius was significantly prolonged by the MP treatment: 13.8 ± 0.5; 14.4 ± 0.6; and 15.3 ± 0.4 days (mean ± SD) in the C, LC, and HC, respectively. This study indicates that even environmentally relevant concentrations of MP mixture have a negative influence on C. riparius, especially at the larval stage.

Malformations of Mouthpart Structures of Chironomusriparius Larvae (Diptera, Chironomidae) under the Effect of Metal-Containing Nanoparticles

The teratogenic effect of metal-containing nanoparticles on the occurrence of malformations in the mouthpart structures of Chironomus riparius Meigen larvae (Diptera, Chironomidae) was confirmed in a long-term experiment. The proportion of larvae with malformations in all the experimental environments was 2.2–8.4 times higher than the control values. Nanoparticles of silver and titanium dioxide (anatase) had the greatest teratogenic effect, the proportion of chironomid larvae with mouthpart deformities reaching 45.3 and 44.6%, respectively.

Induction of Deformities of the Hard-Chitinized Mouthpart Structures of Larvae Chironomus riparius Meigen under Various Contents of Persistent Organic Substances in Bottom Sediments

It is shown that the number of deformations of mouthpart structures of larvae Chironomus riparius reflects the potential danger of contaminated bottom sediments and can serve as a good biomarker when monitoring the ecological status of freshwater ecosystems. The method of quantification of the deformation rate of hard-chitinized structures (mentum and mandibles) has been approbated. It has been revealed that the total amount of polychlorinated biphenyls in bottom sediments affects the portion of larvae with multiple deformations and the relative number of larvae with deformations of mentum and mandibles. Examples of calculating the index of the morphological response of hard-chitinized mouthpart structures of chironomid larvae exposed to bottom sediments with various contents of persistent organic substances are given.

Effects of single and mixture exposure of cadmium and copper in apoptosis and immune related genes at transcriptional level on the midge Chironomus riparius Meigen (Diptera, Chironomidae)

Metals and heavy metals are natural contaminants with an increasing presence in aquatic ecosystems as a result of human activities. Although they are mixed in the water, research is usually focused on analyzing them in isolation, so there is a lack of knowledge about their combined effects. The aim of this work was to assess the damage produced by mixtures of cadmium and copper, two frequent metals used in industry, in the harlequin midge Chironomus riparius (Diptera). The effects of acute doses of cadmium and copper were evaluated in fourth instar larvae by analyzing the mRNA levels of six genes related to apoptosis (DRONC, IAP1), immune system (PO1, Defensin), stress (Gp93), and copper homeostasis (Ctr1). DRONC, Ctr1, and IAP1 transcripts are described here for first time in this species. Individual fourth instar larvae were submitted to 10 μM, 1 μM and 0.1 μM of CdCl2 or CuCl2, and mixture. The employed individuals came from different egg masses. Real-time PCR analysis showed a complex pattern of alterations in transcriptional activity for two genes, DRONC and Gp93, while the rest of them did not show any statistically significant differences. The effector caspase DRONC showed upregulation with the highest concentration tested of the mixture. In case of gp93, chaperone involved in regulation of immune response, differences in expression levels were found with 1 and 10 μM Cu and 0.1 and 10 μM of mixtures, compared to control samples. These results suggest that mixtures affect the transcriptional activity differently and produce changes in apoptosis and stress processes, although it is also possible that Gp93 alteration could be related to the immune system since it is homologous to human protein Gp96, which has been related with Toll-like receptors. In conclusion, cadmium and copper mixtures can affect the population by affecting the ability of larvae to respond to the infection and the apoptosis, an important process in the metamorphosis of insects.

Rapid adaptation to high temperatures in Chironomus riparius.

Effects of seasonal or daily temperature variation on fitness and physiology of ectothermic organisms and their ways to cope with such variations have been widely studied. However, the way multivoltines organisms cope with temperature variations from one generation to the next is still not well understood. The aim of this study was to investigate whether the multivoltine midge Chironomus riparius Meigen (1803) responds mainly via acclimation as predicted by current theories or whether rapid genetic adaptation is involved. To investigate this issue, a common garden approach has been applied. A mix of larvae from five European populations was raised in the laboratory at three different pre‐exposure temperatures (PET): 14, 20, and 26°C. After three and five generations, respectively, larvae were exposed to three treatment temperatures (TT): 14, 20, and 26°C. Mortality was monitored for the first 48 hr and after emergence. After three generations, significant mortality rate differences depended on an interaction of PET and TT. This finding supports the hypothesis that chironomids respond rapidly to climatic variation via adaptive mechanisms and to a lesser extent via phenotypic plasticity. The result of the experiment indicates that three generations were sufficient to adapt to warm temperature, decreasing the mortality rate, highlighting the potential for chironomids to rapidly respond to seasonally changing conditions.

Chromium bioavailability in aquatic systems impacted by tannery wastewaters. Part 2: New insights from laboratory and in situ testing with Chironomus riparius Meigen (Diptera, Chironomidae)

Chromium is widely used as a tanning agent and can become a contaminant of concern in aquatic ecosystems receiving discharges from industrial or artisanal tanning activities. In a companion study, we showed that Cr discharged by tanneries was bioavailable to indigenous chironomids with accumulation via sediment ingestion likely to represent the predominant exposure route. However, Cr accumulation by chironomids did not directly reflect the degree of sediment contamination and the potential adverse effects of Cr accumulation on chironomids were not evaluated. In the present study, chironomids were exposed to homogenised, field-collected sediments in the laboratory and to intact sediments in situ using a customized caging system. Chromium concentrations were assessed in sediments, exposed larvae of laboratory-reared Chironomus riparius and overlying waters of in situ cages. Experimental results of Cr bioaccumulation were compared with expected Cr body burden in chironomids calculated using biodynamic modelling. Our data provided strong support to the hypothesis that Cr bioaccumulation in the field is specifically controlled by the deposition of contaminated suspended particulate matter (SPM) containing a pool of Cr readily bioavailable to surface deposit feeders. Considering freshly deposited SPM as an additional route of exposure for surface deposit feeders leads to a good agreement between the modelling and experimental results. Additionally, a Cr body burden of about 77 μg g−1 d.w. was identified as a tentative threshold above which effects on the growth of C. riparius may appear. While both laboratory and in situ experiments provide evidence for the availability of Cr in aquatic system impacted by tannery wastewaters, standard laboratory exposure conditions may miss additional exposure routes in the field and underestimate possible adverse effects on benthic organisms.

Aquatic silk proteins in Chironomus: A review

Silk proteins secreted by salivary glands in the dipteran insect, Chironomus play a significant role as proteinaceous adhesives for construction of underwater housing nests by larvae. To date, only three Chironomus species, C. tentans Fabricius, C. pallidivittatus Malloch and C. riparius Meigen have been explored for characterization of their aquatic silk protein. Genes coding for silk proteins are located on specific chromosomal ‘puffs’ called Balbiani rings as well as non-Balbiani ring regions. Expression of these genes is closely regulated by developmental and hormonal alterations and environmental factors. Furthermore, pilot studies have postulated that silk proteins probably occur in diverse size classes grouped into large (~1000 kDa), intermediate (100-200 kDa) and small (≤100 kDa). Barring few preliminary reports that date back to the 1990s, the physical and bioproperties of silk from chironomid midges remain largely unknown, leading to paucity of updated information. This review was therefore aimed to compile existing literature database and to highlight the wide possibilities for commercialization of midge larval silk as a novel biopolymer.

Life cycle of natural populations of Metriocnemus (Inermipupa) carmencitabertarum Langton & Cobo 1997 (Diptera: Chironomidae) in The Netherlands: indications for a southern origin?

The life-history and behaviour of the chironomid Metriocnemus (Inermipupa) carmencitabertarum was studied for three years and a comparison was made between two populations in the Netherlands. Key life-history characteristics are reported, including the number of generations (2-5 generations) and duration of larval development (19-55 days). Life-history characteristics differed between the two populations and between generations within a population. These differences were likely related to differences in competitors (mainly Chironomus riparius Meigen) and thermal characteristics of the habitat from variations in water volume and ambient temperature. Results suggested a diapause in summer, when water levels dropped, and not in winter. A clear seasonal pattern in body size was found with pupal length increasing steeply at the beginning of the summer. The increase in body size was positively correlated with mean ambient temperature during larval development. This correlation is in contrast with the Temperature-Size Rule (TSR) in ectotherms, which postulates a negative correlation between temperature and adult body size. The chance of ectotherm predators being present in the habitat is low, which may explain this feature. Life history characteristics supported a recent northward range expansionfor M. (I.) carmencitabertarum due to warmer winters. If correct, it is predicted that the species will be found in Scotland and northern Germany and/or southern Denmark in the near future.

Assessing the suitability of genetic diversity of Chironomus riparius (Meigen) as an indicator of environmental pollution

Reliable and cost-effective indicators are needed to reduce uncertainty in ecological risk assessments of chemicals so that their long-term and evolutionary impacts in the dynamics of stressed biological communities can be accounted for.In the present study we investigate the suitability of genetic diversity as an indicator of ecological disturbance of freshwater ecosystems. For that, we selected three freshwater systems with well-known histories of metal contamination and three nearby reference sites located in Northern Portugal and the effects of metal contamination were assessed both in the levels of genetic diversity of the non-biting midge Chironomus riparius Meigen (at microsatellite markers) and in the diversity and composition of the benthic macroinvertebrate communities.Results showed a remarkable impoverishment in the abundance and diversity of macroinvertebrate communities of metal polluted sites in which most sensitive taxa were eliminated and replaced by more opportunistic ones belonging mainly to Oligochaeta and Diptera. In contrast, no evidence for pollution-induced genetic erosion was found in C. riparius populations in the studied area, with genetic diversity of the species being indeed higher in sites with impoverished macroinvertebrate communities and poor habitat quality.Our findings suggest that there are important limitations to the use of measures of genetic diversity of C. riparius per se to unravel ecological disturbance. Field studies aiming at quantifying pollutant-driven genetic erosion need to carefully consider the ecological and demographic aspects of potential target species.

济南河流大型底栖动物摄食功能群多样性及时空动态

PDF HTML阅读 XML下载 导出引用 引用提醒 济南河流大型底栖动物摄食功能群多样性及时空动态 DOI: 10.5846/stxb201608111643 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 辽宁省优秀人才支持计划项目（LR2015009）；山东省水利厅、山东省财政厅"水生态文明试点科技支撑计划"（SSTWMZCJH-SD02）；济南市水生态时空变异驱动机制及自动监测模式；国家自然科学基金（51279005） Diversity and temporal-spatial dynamics of macroinvertebrate functional feeding groups in the rivers of the Jinan Region Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:2014年春季（5月）、夏季（8月）和秋季（11月）对济南地区24个样点的大型底栖动物和水环境理化因子进行了野外调查。利用多样性指数以及典范对应分析等方法，分析了大型底栖动物群落组成和空间结构特征。结果表明：共采集到大型底栖动物3门57种，分别为节肢动物门、软体动物门和环节动物门。春季、夏季和秋季采集到大型底栖动物45种、35种和33种，春季优势种为霍甫水丝蚓（Limnodrilus hoffmeisteri）和豆螺（Bithynia fuchsiana），夏季优势种为溪流摇蚊（Chironomus riparius）和豆螺（Bithynia fuchsiana），秋季优势种为喜盐摇蚊（Chironomus salinarius）和豆螺（Bithynia fuchsiana）。春季、夏季和秋季密度平均值为2.49×103、0.56×103、1.03×103 个体/m2；生物量平均值为495.59、137.26、109.45 g/m2；Shannon-Wiener指数平均值分别为1.37、1.33和1.17；均匀度指数平均值分别为0.55、0.67和0.59。全地区共划分出大型底栖动物功能摄食类群5类，春季收集者种类最多为20种，夏季刮食者种类最多为12种，秋季收集者与刮食者种类最多为11种，3个季节中收集者密度均占绝对优势，其次为刮食者。典范对应分析表明，春季影响黄河流域和淮河流域大型底栖动物功能摄食类群的主要环境因子是总磷和总氮；夏季影响黄河流域和淮河流域大型底栖动物功能摄食类群的主要环境因子是pH和溶解氧；秋季影响黄河流域和淮河流域大型底栖动物功能摄食类群的主要环境因子是溶解氧和pH。 Abstract:The objective of the study was to show the relationship between the community structure of macroinvertebrate and the associated environmental factors, based on Independent sample t test method, scatter plot analysis method, classification of macroinvertebrate functional feeding groups and Canonical correspondence analysis and other methods in Jinan Region from spring 2014 (May) to autumn 2014(November). We identified 57 macroinvertebrate species,consist of Arthropoda,Mollusca and Annelida,We identified 45,35 and 33 macroinvertebrate species in spring,summer and autumn, Bithynia fuchsiana was the dominant class, followed by Limnodrilus hoffmeisteri,Chironomus riparius Meigen and then Chironomus salinarius Kiffer. The average values of macroinvertebrate densities, Biomass, Shannon-Wiener index and Pielou index ranged from 0.56×103 ind/m2 to 2.49×103 ind/m2, from 109.45 g/m2 to 495.59 g/m2,from 4.55 to 3.75,from0.55 to 0.67 from spring to autumn, respectively. Overall, we categorized these taxa into following five functional feeding groups, Gather-collectors density are dominant.Canonical correspondence analysis results showed that macroinvertebrate community structure was largely determined by the interactions between total phosphorus and total nitrogen in spring in Huang River Basin and Huai River Basin. Dissolved oxygen and pH was the main environmental factors limitation of macroinvertebrate community structure in summer in Huang River Basin and Huai River Basin. In autumn, the primarily environmental factors limiting macroinvertebrate community was dissolved oxygen and pH in Huang River Basin and Huai River Basin. 参考文献 相似文献 引证文献

Hypoxia and anoxia effects on alcohol dehydrogenase activity and hemoglobin content in Chironomus riparius Meigen, 1804

<p>The metabolic effects of low oxygen content on alcohol-dehydrogenase (ADH) activity and hemoglobin (Hb) concentration were investigated in IV-instar larvae of <em>Chironomus riparius </em>(Diptera: Chironomidae) from an Italian stream. Two series of short-term (48 h) experiments were carried out: exposure to (1) progressive hypoxia (95 to 5% of oxygen saturation) and (2) anoxia (at <5% of oxygen saturation). In (1), Hb amount increased with increasing oxygen depletion up to a critical value of oxygenation (about 70% of oxygen saturation). Below this percentage, the Hb amount declined to values comparable with those present in the control. The respiration rate (R) remained almost constant at oxygen saturation >50% and decreased significantly only after 48 h of treatment (= <5% of oxygen saturation) reaching values <100 mmolO<sub>2</sub> gAFDW<sup>-1</sup> h<sup>-1</sup>. ADH activity showed two phases of growth, within the first 14 h and over 18 h of exposure. Overall, we inferred that i) Hb might function as short-term oxygen storage, enabling animals to delay the on-set of anaerobiosis; and ii) alcoholic fermentation co-occurs for a short time with aerobic respiration, becoming the prevalent metabolic pathway below 5% of oxygen saturation (<1 mg L<sup>-1</sup>). These considerations were supported also by results from anoxia exposure (2). In such condition, larvae were visibly stressed, becoming immobile after few minutes of incubation, and ADH reached higher values than in the hypoxia treatment (2.03±0.15 UADH mg prot<sup>-1</sup>). Overall, this study showed a shift from aerobic to anaerobic activity in <em>C. riparius</em> larvae exposed to poorly oxygenated water with an associated alteration of ADH activity and the Hb amount. Such metabolites might be valid candidate biomarkers for the environmental monitoring of running waters.</p>

The effect of zinc oxide nano- and microparticles and zinc ions on freshwater organisms of different trophic levels

Data on the effects of various forms of zinc compounds on the biological parameters of freshwater animals (Ceriodaphnia affinis Lillijeborg, 1862; Chironomus riparius Meigen, 1804; and Brachydanio rerio Hamilton-Buchanan, 1822) are presented. Crustacean Ceriodaphnia affinis is the most sensitive test object studied.

Effects of water temperature on development and heavy metal toxicity change in two midge species of Chironomus riparius and C. yoshimatsui in an era of rapid climate change

AbstractClimate change is the most significant stressor that is anticipated increasingly to affect human and global ecosystems. Arthropods, including insects, are particularly vulnerable to global warming and this group is often used for various ecotoxicological tests. In addition, temperature is one of the most important toxicity‐modifying factors in ecotoxicology. Therefore, temperature dependent toxicological research is required to obtain ecologically relevant conclusions during the current era of rapid climate change. This study shows that two midge species (Chironomus riparius Meigen and C. yoshimatsui Martin et Sublette) exhibit different developmental characteristics and responses to cadmium and lead heavy metals with temperature. The former species is an internationally standardized test species in ecotoxicological studies, whereas the latter species is native to Korea. Hence, even though these two species belong to the same genus, Chironomus, their development differs with temperature, which leads to different responses to heavy metals. There was a decline in developmental time (from egg and larva to pupa) for both species with temperature; however, there was a species difference in the rate of decline. In the acute toxicity test, the 48‐hr LC50 values for cadmium and lead decreased with temperature for both species. In the chronic toxicity test, emergence rates tended to decrease with temperature, except for when C. yoshimatsui was exposed to cadmium.

Toxicological and teratogenic assessment of bottom sediments from the Rybinsk Reservoir

The toxicity of bottom sediments (BSs) from different parts of the Rybinsk Reservoir has been determined by biotesting. Neither acute nor chronic toxicity are detected for ceriodaphnia Ceriodaphnia affinis Lillijeborg in tests with water extracts of sediments from all the investigated stations. The relative number of Chironomus riparius Meigen larvae with deformed mouth structures in the specimens exposed to the BSs of the reservoir is higher than in the control. Abnormalities of the mentum and mandibules (heavily chitinized structures) were the most often observed pathomorphological disturbances. The results of this study suggest that BSs from the stations located near the Cherepovets Industrial Complex (CIC) may be classified as contaminated.

Effects of imidacloprid exposure on Chironomus riparius Meigen larvae: Linking acetylcholinesterase activity to behaviour

Imidacloprid (IMI) is an insecticide that interferes with the transmission of stimuli in the nervous system of insects. It is neurotoxic by mimicking nicotine through its binding to the nicotinic acetylcholine receptor. In this work, experiments comprising 96 h exposure followed by 48 h in clean medium were conducted to evaluate the toxicity of IMI to Chironomus riparius and its potential recovery. Behavioural parameters and AChE activity were assessed. After 96 h exposure to IMI, AChE activity, and the behaviour parameters ventilation and locomotion were reduced. There were no signs of recovery after removal to clean water for 48 h. Ventilation behaviour was the most sensitive parameter and the one with the highest correlation to AChE activity. Despite the possibility that IMI might be having an indirect effect on AChE activity, the behavioural endpoint showed a higher sensitivity than the biochemical response itself. This work highlights the importance of linking parameters with ecological relevance at individual level (behavioural parameters) with biochemical responses, to unravel xenobiotics mode of action.

Acute toxicity analysis of polyelectrolyte microcapsules with zinc oxide nanoparticles and microcapsule shell components using aquatic organisms

Nanocomposite microcapsules with zinc oxide nanoparticles in their shells were fabricated using layer-by-layer assembly. An investigation of the toxic effect of microcapsules and their constituent components was performed for four types of test objects (ceriodaphnids (Ceriodaphnia affinis Lilljeborg), the Ekolyum biosensor (a culture of fluorescent genetically engineered Escherichia coli M-17 bacteria), midge larvae (Chironomus riparius Meigen), and aquarium fish (Brachydanio rerio)). It was established that, for each test object, the poly(allylamine hydrochloride) solution (PAH) used as a constituent component for the microcapsule shell formation has the maximal toxicity. The poly(sodium styrene sulfonate) solution (PSS) and a sample of microcapsules with a shell structure of (PAH/PSS)2(ZnO/PSS)3(PAH/PSS) have the least toxicity among the tested samples. At the same time, a significant decrease in the acute toxicity effect for the suspension of the microcapsules in comparison with their constituent components was detected. In the future, our results can be used in the development of a complex methodology for determining the toxicity parameters of a microcapsule, as well as the polyelectrolytes and inorganic nanoparticle colloids used as the initial material for the fabrication of nanocomposite microcontainers.