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Sample records for freshwater cladoceran daphnia

  1. How does the cladoceran Daphnia pulex affect the fate of Escherichia coli in water?

    PubMed Central

    Burnet, Jean-Baptiste; Faraj, Tarek; Cauchie, Henry-Michel; Joaquim-Justo, Célia; Servais, Pierre; Prévost, Michèle; Dorner, Sarah M.

    2017-01-01

    The faecal indicator Escherichia coli plays a central role in water quality assessment and monitoring. It is therefore essential to understand its fate under various environmental constraints such as predation by bacterivorous zooplankton. Whereas most studies have examined how protozooplankton communities (heterotrophic nanoflagellates and ciliates) affect the fate of E. coli in water, the capacity of metazooplankton to control the faecal indicator remains poorly understood. In this study, we investigated how the common filter-feeding cladoceran, Daphnia pulex, affects the fate of E. coli under different experimental conditions. Daphnia ingested E. coli and increased its loss rates in water, but the latter rates decreased from 1.65 d-1 to 0.62 d-1 after a 1,000-fold reduction in E. coli initial concentrations, due to lower probability of encounter between Daphnia and E. coli. The combined use of culture and PMA qPCR (viability-qPCR) demonstrated that exposure to Daphnia did not result into the formation of viable but non-culturable E. coli cells. In lake water, a significant part of E. coli population loss was associated with matrix-related factors, most likely due to predation by other bacterivorous biota and/or bacterial competition. However, when exposing E. coli to a D. pulex gradient (from 0 to 65 ind.L-1), we observed an increasing impact of Daphnia on E. coli loss rates, which reached 0.47 d-1 in presence of 65 ind.L-1. Our results suggest that the filter-feeder can exert a non-negligible predation pressure on E. coli, especially during seasonal Daphnia population peaks. Similar trials using other Daphnia species as well as stressed E. coli cells will increase our knowledge on the capacity of this widespread zooplankter to control E. coli in freshwater resources. Based on our results, we strongly advocate the use of natural matrices to study these biotic interactions in order to avoid overestimation of Daphnia impact. PMID:28178322

  2. Life table evaluation of the effects of cadmium exposure on the freshwater cladoceran, Moina macrocopa

    SciTech Connect

    Wong, C.K.; Wong, P.K. )

    1990-01-01

    Of many organisms in freshwater environments, crustacean zooplankton appears to be the most sensitive to cadmium. In spite of the importance of zooplankton in freshwater communities and the sensitivity of zooplankters to cadmium toxicity, little information on the effects of cadmium on zooplankton species other than Daphnia is available. The freshwater cladoceran Moina macrocopa Straus is widely distributed. In Hong Kong it is common in small ponds and rice paddies and is mass cultured by local fish farmers as a fish food. Its small size and high reproductive rate in the laboratory make it an ideal test organism for aquatic toxicologists. The purpose of this paper is to use the life table method to study the effect of cadmium on the survival and reproductive capacity of this commercially important zooplankter.

  3. Toxicity of ivermectin on cladocerans: comparison of toxic effects on Daphnia and Ceriodaphnia species.

    PubMed

    Lopes, Christelle; Charles, Sandrine; Vollat, Bernard; Garric, Jeanne

    2009-10-01

    Interspecies differences in contaminant sensitivity are measured to assess environmental risk based on species sensitivity distribution. The present study was intended to demonstrate the importance of studying the effects of contaminants on the life-history traits of various species. To do this, we compared the effects of ivermectin on the survival, growth, and reproduction of two cladoceran species (Daphnia magna and Ceriodaphnia dubia) and two strains of D. magna (one Japanese and one European). Ivermectin is widely used against endo- and ectoparasites in livestock and pets and is known for its high toxicity. Local aquatic ecosystems can be contaminated due to direct excretion into surface waters, but few data are available about the chronic effects of ivermectin on aquatic organisms. Adult daphnids were exposed to concentrations from 0 to 1 ng/L. Our results show a significant effect on all the life-history traits measured and reveal inter- and intraspecies differences. The no-observed-effect concentration found for growth and reproduction is 0.0003 ng/L for D. magna versus 0.001 ng/L for C. dubia, and the lowest-observed-effect concentration is 0.001 ng/L for D. magna versus 0.01 ng/L for C. dubia. C. dubia is smaller than D. magna and appeared to be less sensitive to ivermectin. The European strain of D. magna exhibited less resistance than the Japanese strain. A bias in the sex ratio was observed for all strains tested.

  4. Bioavailability and toxicity of trace metals to the cladoceran Daphnia magna in relation to cadmium exposure history

    NASA Astrophysics Data System (ADS)

    Guan, Rui

    The cladoceran Daphnia magna is widely used in freshwater bioassessments and ecological risk assessments. This study designed a series of experiments employing radiotracer methodology to quantify the trace metals (mainly Cd and Zn) biokinetics in D. magna under different environmental and biological conditions and to investigate the influences of different Cd exposure histories on the bioavailability and toxicity of trace metals to D. magna. A bioenergetic-based kinetic model was finally applied in predicting the Cd accumulation dynamics in D. magna and the model validity under non-steady state was assessed. Cd assimilation was found in this study to be influenced by the food characteristics (e.g., metal concentration in food particles), the metal exposure history of the animals, and the genetic characteristics. Some of these influences could be interpreted by the capacity and/or competition of those metal binding sites within the digestive tract and/or the detoxifying proteins metallothionein (MT). My study demonstrated a significant induction of MT in response to Cd exposure and it was the dominant fraction in sequestering the internal nonessential trace metals in D. magna. The ratio of Cd body burden to MT might better predict the Cd toxicity on the digestion systems of D. magna than the Cd tissue burden alone within one-generational exposure to Cd. It was found that metal elimination (rate constant and contribution of different release routes) was independent of the food concentration and the dietary metal concentration, implying that the elimination may not be metabolically controlled. The incorporation of the bioenergetic-based kinetic model, especially under non-steady state, is invaluable in helping to understand the fate of trace metals in aquatic systems and potential environmental risks. The dependence of biokinetic parameters on environmental factors rather than on genotypes implies a great potential of using biokinetics in inter-laboratory comparisons.

  5. Acute and chronic ecotoxicological effects of four pharmaceuticals drugs on cladoceran Daphnia magna.

    PubMed

    de Oliveira, Laira L Damasceno; Antunes, Sara Cristina; Gonçalves, Fernando; Rocha, Odete; Nunes, Bruno

    2016-01-01

    The occurrence of pharmaceuticals in the aquatic environment has received increasing attention in recent years, as concerns have risen about their environmental persistence, biological activity and different effects toward nontarget organisms. Considering the magnitude of concentrations (ng L(-1) to mg L(-1)) and their often-specific modes of action, the assessment of physiological responses of exposed aquatic biota may provide significant information regarding the potential ecological consequences of exposure to these contaminants. The present study intended to assess the acute and chronic effects of four pharmaceuticals: acetaminophen, chlorpromazine, diclofenac sodium and propranolol in the cladoceran species Daphnia magna. Parameters such as immobility, total of offspring and rate of population increase were analyzed. Results of acute exposures showed a considerable variability of toxicity among pharmaceuticals, with the following ranking of toxicity: diclofenac (EC50 = 123.3 mg L(-1)) < propranolol (EC50 = 5.531 mg L(-1)) < acetaminophen (EC50 = 2.831 mg L(-1)) < chlorpromazine (EC50 = 1.805 mg L(-1)). The chronic toxicity data showed the exertion of reproductive adverse effects. The compounds chlorpromazine and propranolol caused a significant decrease in fecundity, and the rate of population increase parameter suffered a significant decrease from 0.33 mg L(-1) to 0.128 mg L(-1) onwards, respectively. The levels of exposure to which our test organism was acutely and chronically exposed were above those already reported in the wild. Nevertheless, the extensive production, prescription and release of pharmaceuticals drugs will continue to grow in the future, and consequently their loadings to the environment can result in potential long-term ecological risks to aquatic biota.

  6. Genomic identification of a putative circadian system in the cladoceran crustacean Daphnia pulex

    PubMed Central

    Tilden, Andrea R.; McCoole, Matthew D.; Harmon, Sarah M.; Baer, Kevin N.; Christie, Andrew E.

    2011-01-01

    Essentially nothing is known about the molecular underpinnings of crustacean circadian clocks. The genome of Daphnia pulex, the only crustacean genome available for public use, provides a unique resource for identifying putative circadian proteins in this species. Here, the Daphnia genome was mined for putative circadian protein genes using Drosophila melanogaster queries. The sequences of core clock (e.g. CLOCK, CYCLE, PERIOD, TIMELESS and CRYPTOCHROME 2), clock input (CRYPTOCHROME 1) and clock output (PIGMENT DISPERSING HORMONE RECEPTOR) proteins were deduced. Structural analyses and alignment of the Daphnia proteins with their Drosophila counterparts revealed extensive sequence conservation, particularly in functional domains. Comparisons of the Daphnia proteins with other sequences showed that they are, in most cases, more similar to homologs from other species, including vertebrates, than they are to those of Drosophila. The presence of both CRYPTOCHROME 1 and 2 in Daphnia suggests the organization of its clock may be more similar to that of the butterfly Danaus plexippus than to that of Drosophila (which possesses CRYPTOCHROME 1 but not CRYPTOCHROME 2). These data represent the first description of a putative circadian system from any crustacean, and provide a foundation for future molecular, anatomical and physiological investigations of circadian signaling in Daphnia. PMID:21798832

  7. Effects of Ammonia and Density on Filtering of Commensal and Pathogenic Escherichia coli by the Cladoceran Daphnia magna.

    PubMed

    Nørgaard, Louise Solveig; Roslev, Peter

    2016-12-01

    Grazing by cladocerans can reduce the survival of enteric bacteria associated with fecal pollution. This study examined the potential of Daphnia magna to filter commensal and pathogenic Escherichia coli of human origin. Grazing on commensal and pathogenic bacteria was comparable, but slightly greater at 20 compared to 15 and 25°C. Filtering activity was strongly dependent on D. magna and E. coli densities at environmentally relevant bacterial concentrations. Maximum feeding rates were >10(7) cells h(-1) daphnid(-1), clearance rates were 1-6 mL h(-1) daphnid(-1), and filtering was independent of bacterial cell sizes between 0.7 and 1.8 µm. Filtering and ingestion of E. coli by D. magna was susceptible to acute inhibition by unionized ammonia with a 24 h EC50 of 0.18 mg L(-1) NH3-N, and a LOEC of 0.09 mg L(-1) NH3-N. The study indicated that biological and chemical constraints should be considered when applying Daphnia for attenuation of fecal pollution.

  8. Sensitivity of Costa Rica's native cladoceran Daphnia ambigua and Simocephalus serrulatus to the organophosphate pesticide ethoprophos.

    PubMed

    Arias-Andrés, María; Torres, Freylan Mena; Vargas, Seiling; Solano, Karla

    2014-01-01

    The study of pesticide toxicity in aquatic environments is assessed with ecotoxicological tests and most research has been performed using species from temperate regions. In the present study, series of acute (48 hrs) toxicity tests to compare the sensibility of two indigenous cladocera of Costa Rica and two reference species were used in temperate regions to the organophosphate pesticide, Ethoprophos. Additionally, reproduction tests using S. serrulatus with sub lethal concentrations of ethoprophos and a control were assayed to check its sensitivity over a longer period exposure. The sensitivity of Costa Rica's native species Daphnia ambigua (EC50 48 hr: 12.9 +/- 3.0 microg(l(-1)) and Simocephalus serrulatus (10.6 +/- 2.1 microg l(-1)) to ethoprophos were higher (p < 0.05) when compared to the exotic species Daphnia magna (289.8 +/- 77.4 microg l(-1)), and were comparable to that of the more widely distributed species, Ceriodaphnia dubia (18.2 +/- 5.2 microg l(-1)). No effect on S. serrulatus reproduction was observed at concentrations between 1 and 4 microg l(-1). This study provides information that can be considered in the selection of species for ecosystem studies of pesticide toxicity in neotropical regions.

  9. Gravity Perception in a Cladoceran-zooplankter: Anatomy of Antennal Socket Setae of Daphnia Magna

    NASA Technical Reports Server (NTRS)

    Meyers, D. G.

    1985-01-01

    Night orientation in Daphnia magna was recently associated with setae on the basal socket of the swimming antennae. Daphnids are suspected of maintaining nocturnal equilibrium by monitoring the gravity vector through upward setal deflections caused by sinking between antennal swimming strokes. Setae appear to be hydrodynamic rheoceptors that sense the gravity vector indirectly by mechanoreceptivity to the direction and velocity of water currents. Neuroanatomical stains have revealed cell bodies at the base of the setal shafts, dendritic connections through to the distal ends of the shafts, and axonal tracts around the antennal socket connecting with an additional cell body and continuing toward the brain. These anatomical observations combined with previous scanning electron microscopy studies suggest that the setae are similar to mechanoreceptors and propreceptors used by higher crustaceans to sense water currents and gravity, and maintained balance.

  10. A comparison of the response of Simocephalus mixtus (Cladocera) and Daphnia magna to contaminated freshwater sediments.

    PubMed

    Martínez-Jerónimo, Fernando; Cruz-Cisneros, Jade Lizette; García-Hernández, Leonardo

    2008-09-01

    The southeast region of Mexico is characterized by intensive oil industry activities carried out by the national public enterprise Petróleos Mexicanos (PEMEX). The freshwater lagoon "El Limón", located in the municipality of Macuspana, state of Tabasco, Mexico, has received over 40 years discharges of untreated waste waters from the Petrochemical Complex "Ciudad PEMEX", located on the border of the lagoon. To assess the toxicity of the sediments and, hence, to obtain information on the biological effects of these contaminating discharges, the cladoceran Simocephalus mixtus was used as a test organism in acute (48h) and chronic (12d) toxicity assays. For comparison purposes, bioassays were also conducted with the reference cladoceran Daphnia magna. The sediments of this lagoon contain important amounts of metals and hydrocarbons that have been accumulated over time; however, the acute tests only registered reduced lethal effects on the test organisms (maxima of 10% and 17% mortality for D. magna and S. mixtus, respectively). This may be due to low bioavailability of the pollutants present in the sediments. On the other hand, partial or total inhibition and delay in the start of reproduction, reduction in clutch sizes, reduced survival, as well as reduction in the size of adults and offspring were recorded in the chronic assays. The most evident chronic effects were found in S. mixtus; in this species, reproduction was inhibited up to 72%, whereas D. magna was only affected by 24%. We determined that S. mixtus is a more sensitive test organism than D. magna to assess whole-sediment toxicity in tropical environments, and that chronic exposure bioassays are required for an integrated sediment evaluation. The sediments from "El Limón" lagoon induced chronic intoxication responses and, therefore, remediation measures are urgently needed to recover environmental conditions suitable for the development of its aquatic biota.

  11. Chronic exposure to diclofenac on two freshwater cladocerans and Japanese medaka.

    PubMed

    Lee, Jinyoung; Ji, Kyunghee; Lim Kho, Young; Kim, Pilje; Choi, Kyungho

    2011-07-01

    Consequences of long-term exposure to diclofenac up to 3 months were evaluated using freshwater crustaceans (Daphnia magna and Moina macrocopa) and a fish (Oryzias latipes). Marked decrease of reproduction was observed at 25 mg/L for D. magna, and at 50 mg/L for M. macrocopa. Three-month exposure of fish to 0.001-10 mg/L of diclofenac resulted in significant decreasing trend in hatching success and delay in hatch. The hatching of the eggs produced from the fish exposed to 10 mg/L was completely interfered, while fertility of the parent generation was not affected. Gonadosomatic index (GSI) of female fish was also affected at 10 mg/L. Predicted no effect concentration of diclofenac was estimated at 0.1 mg/L, which is a few orders of magnitude greater than those observed in ambient water. Therefore direct impact of diclofenac exposure is not expected. However its bioaccumulation potential through food web should warrant further evaluation.

  12. CHRONIC EFFECTS OF THE HERBICIDE DIURON ON FRESHWATER CLADOCERANS,AMPHIPODS,MIDGES,MINNOWS,WORMS, AND SNAILS

    EPA Science Inventory

    The chronic effects of the herbicide diuron on survival and reproduction of Daphnia pulex, and survival and growth of the amphipod Hyalella azteca, the midge Chironomus tentans, juvenile and embro/larval fathead minnows, Pimephales promelas, annelid worms, Lumbriculus variegatus,...

  13. Chronic toxicity of azoxystrobin to freshwater amphipods, midges, cladocerans, and mussels in water-only exposures.

    PubMed

    Kunz, James L; Ingersoll, Chris G; Smalling, Kelly L; Elskus, Adria A; Kuivila, Kathryn M

    2017-02-09

    Understanding the effects of fungicides on nontarget organisms at realistic concentrations and exposure durations is vital for determining potential impacts on aquatic ecosystems. Environmental concentrations of the fungicide azoxystrobin have been reported up to 4.6 μg/L in the United States and 30 μg/L in Europe. The objective of the present study was to evaluate the chronic toxicity of azoxystrobin in water-only exposures with an amphipod (Hyalella azteca; 42-d exposure), a midge (Chironomus dilutus; 50-d exposure), a cladoceran (Ceriodaphnia dubia; 7-d exposure), and a unionid mussel (Lampsilis siliquoidea; 28-d exposure) at environmentally relevant concentrations. The potential photo-enhanced toxicity of azoxystrobin accumulated by C. dubia and L. siliquoidea following chronic exposures to azoxystrobin was also evaluated. The 20% effect concentrations (EC20s) based on the most sensitive endpoint were 4.2 μg/L for H. azteca reproduction, 12 μg/L for C. dubia reproduction and C. dilutus emergence, and >28 μg/L for L. siliquoidea. Hyalella azteca was more sensitive to azoxystrobin compared with the other 3 species in the chronic exposures. No photo-enhanced toxicity was observed for either C. dubia or L. siliquoidea exposed to ultraviolet light in control water following azoxystrobin tests. The results of the present study indicate chronic effects of azoxystrobin on 3 of 4 invertebrates tested at environmentally relevant concentrations. The changes noted in biomass and reproduction have the potential to alter the rate of ecological processes driven by aquatic invertebrates. Environ Toxicol Chem 2017;9999:1-8. Published 2017 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

  14. Toxicity of laundry detergent components to a freshwater cladoceran and their contribution to detergent toxicity.

    PubMed

    Warne, M S; Schifko, A D

    1999-10-01

    The toxicity of 39 laundry detergent components including surfactants, enzymes, builders, fabric brighteners, fillers, and coloring agents to the cladoceran Ceriodaphnia cf. dubia was determined. The difference between the most and the least toxic components was approximately 17,000-fold and 1,000,000-fold for the mg/L and mmol/L EC50 data, respectively. Two of the components had high toxicity (EC50 values < 1 mg/L), 11 moderate toxicity (EC50 values between 1 and 10 mg/L), and the remaining 26 components had low toxicity (EC50 values > 10 mg/L). Analysis revealed that mixtures of the components interacted antagonistically, additively, and synergistically. On a molarity basis the most toxic group of compounds was the surfactants followed by the brighteners. The most toxic individual components included sodium carboxymethyl cellulose, sodium silicate solution, four brighteners, sodium perborate tetrahydrate, and the surfactants. Many of the most toxic components, however, contributed very little to the toxicity of the detergents due to being present in the detergents at low concentrations. The main contributors to the toxicity of detergents were the sodium silicate solution and the surfactants-with the remainder of the components contributing very little to detergent toxicity. The potential for acute aquatic toxic effects due to the release of secondary or tertiary sewage effluents containing the breakdown products of laundry detergents may frequently be low. However, untreated or primary treated effluents containing detergents may pose a problem. Chronic and/or other sublethal effects that were not examined in this study may also pose a problem.

  15. Arginine kinase in the cladoceran Daphnia magna: cDNA sequencing and expression is associated with resistance to toxic Microcystis.

    PubMed

    Lyu, Kai; Zhang, Lu; Zhu, Xuexia; Cui, Guilian; Wilson, Alan E; Yang, Zhou

    2015-03-01

    Nutrient loading derived from anthropogenic activities into lakes have increased the frequency, severity and duration of toxic cyanobacterial blooms around the world. Although herbivorous zooplankton are generally considered to be unable to control toxic cyanobacteria, populations of some zooplankton, including Daphnia, have been shown to locally adapt to toxic cyanobacteria and suppress cyanobacterial bloom formation. However, little is known about the physiology of zooplankton behind this phenomenon. One possible explanation is that some zooplankton may induce more tolerance by elevating energy production, thereby adding more energy allocation to detoxification expenditure. It is assumed that arginine kinase (AK) serves as a core in temporal and spatial adenosine triphosphate (ATP) buffering in cells with high fluctuating energy requirements. To test this hypothesis, we studied the energetic response of a single Daphnia magna clone exposed to a toxic strain of Microcystis aeruginosa, PCC7806. Arginine kinase of D. magna (Dm-AK) was successfully cloned. An ATP-gua PtransN domain which was described as a guanidine substrate specificity domain and an ATP-gua Ptrans domain which was responsible for binding ATP were both identified in the Dm-AK. Phylogenetic analysis of AKs in a range of arthropod taxa suggested that Dm-AK was as dissimilar to other crustaceans as it was to insects. Dm-AK transcript level and ATP content in the presence of M. aeruginosa were significantly lower than those in the control diet containing only the nutritious chlorophyte, Scenedesmus obliquus, whereas the two parameters in the neonates whose mothers had been previously exposed to M. aeruginosa were significantly higher than those of mothers fed with pure S. obliquus. These findings suggest that Dm-AK might play an essential role in the coupling of energy production and utilization and the tolerance of D. magna to toxic cyanobacteria.

  16. The Interactive Effects of Ammonia and Microcystin on Life-History Traits of the Cladoceran Daphnia magna: Synergistic or Antagonistic?

    PubMed Central

    Yang, Zhou; Lü, Kai; Chen, Yafen; Montagnes, David J. S.

    2012-01-01

    The occurrence of Microcystis blooms is a worldwide concern that has caused numerous adverse effects on water quality and lake ecology. Elevated ammonia and microcystin concentrations co-occur during the degradation of Microcystis blooms and are toxic to aquatic organisms; we studied the relative and combined effects of these on the life history of the model organism Daphnia magna. Ammonia and microcystin-LR treatments were: 0, 0.366, 0.581 mg L−1 and 0, 10, 30, 100 µg L−1, respectively. Experiments followed a fully factorial design. Incubations were 14 d and recorded the following life-history traits: number of moults, time to first batch of eggs, time to first clutch, size at first batch of eggs, size at first clutch, number of clutches per female, number of offspring per clutch, and total offspring per female. Both ammonia and microcystin were detrimental to most life-history traits. Interactive effects of the toxins occurred for five traits: the time to first batch of eggs appearing in the brood pouch, time to first clutch, size at first clutch, number of clutches, and total offspring per female. The interactive effects of ammonia and microcystin appeared to be synergistic on some parameters (e.g., time to first eggs) and antagonistic on others (e.g., total offspring per female). In conclusion, the released toxins during the degradation of Microcystis blooms would result, according to our data, in substantially negative effect on D. magna. PMID:22403641

  17. Chronic effects of temperature and nitrate pollution on Daphnia magna: Is this cladoceran suitable for widespread use as a tertiary treatment?

    PubMed

    Maceda-Veiga, Alberto; Webster, Gordon; Canals, Oriol; Salvadó, Humbert; Weightman, Andrew J; Cable, Jo

    2015-10-15

    Effluent clarification and disinfection are major challenges in wastewater management. The cladoceran Daphnia magna has been proposed as a cost-effective and ecosystem-friendly option to clarify and disinfect secondary effluents, but its efficacy has not been fully tested under different sewage conditions. The present study explores the effects of temperature and nitrate on the efficacy of D. magna as a tertiary treatment at two different scales (individual assays and microcosms). Individual assays were employed to determine direct effects of temperature and/or nitrate on D. magna cultured in a suspension of organic matter. Using microcosms under the same environmental conditions, we explored the clearing efficacy of D. magna interacting with a natural microbial community. Individual assays revealed that D. magna mortality increased by 17% at 26 °C, 21% at >250 mg NO3(-)/l and by 60% at 26 °C and at >250 mg NO3(-)/l, and individuals displayed reduced body size, filtering rates and fecundity when compared to those at 21 °C and <40 mg NO3(-)/l. Improved performance under these conditions was also mirrored in the microcosms, with a higher density of D. magna (>100 ind/l) at 21 °C and <40 mg NO3(-)/l compared to the number (0-21 ind/l) at 26 °C and/or >250 mg NO3(-)/l. In the microcosms at 21 °C and <40 mg NO3(-)/l, turbidity and the density of bacteria, protists and micro-metazoa decreased in relation to those at 26 °C and/or >250 mg NO3(-)/l. Each treatment developed a unique and characteristic microbial assemblage, and D. magna was identified as the major driver of the community structure of protists and micro-metazoa. This enabled us to determine taxa vulnerability to D. magna grazing, and to re-define their tolerance thresholds for nitrate. In conclusion, this study increases our knowledge of how microbes respond to temperature and nitrate pollution, and highlights that D. magna efficacy as a tertiary treatment can be seriously

  18. Cladoceran zooplankton abundance under clear and snow-covered ice

    USGS Publications Warehouse

    DeBates, T.J.; Chipps, S.R.; Ward, M.C.; Werlin, K.B.; Lorenzen, P.B.

    2003-01-01

    We described the distribution of cladoceran zooplankton under the ice in a natural, glacial lake. Local light availability apparently altered the spatial distribution of cladocerans. Light levels measured under snow-covered areas (0.178 lux) were an order of magnitude less than those measured at the same depth under clear ice (1.750 lux). Cladoceran density under snow-covered areas was significantly higher (Bosmina spp.=3.34/L; Daphnia spp.=0.61/L) than cladoceran abundance under clear ice (Bosmina spp.=0.91/L; Daphnia spp.=0.19/L).

  19. Feeding and filtration rates of zooplankton (rotifers and cladocerans) fed toxic cyanobacterium (Microcystis aeruginosa).

    PubMed

    Pérez-Morales, Alfredo; Sarma, S S S; Nandini, S

    2014-11-01

    Microcystis aeruginosa is generally dominant in many Mexican freshwater ecosystems interacting with zooplankton species. Hence, feeding and filtration rates were quantified for three cladoceran (Daphnia pulex, Moina micrura and Ceriodaphnia dubia) and three rotifer species (Brachionus calyciflorus, Brachionus rubens and Plationus patulus) using sonicated M. aeruginosa alone or mixed with Scenedesmus acutus in different proportions (25, 50 and 75%, based on cell density), offering a combined initial density of 100,000 cells·ml(-1). All the three cladoceran species ingested M. aeruginosa (100-300 cells ind(-1) min(-1)) when fed exclusively with cyanobacterium. When green alga offered as exclusive diet, the number of cells ingested by the tested cladocerans varied from 80 to 400 cells ind(-1) min(-1). Compared to cladocerans, rotifers in general consumed much lower quantity (< 200 cells ind(-1) min(-1)) of M. aeruginosa and S. acutus. The filtration rate for Daphnia pulex was inversely related to the proportion of green alga in the diet. For other tested cladocerans, no such clear trend was evident. In mixed treatments containing M. aeruginosa, the filtration rate of Daphnia was highest (about 220 μl ind(-1) min(-1)) when the medium contained 75% of S. acutus. Among the rotifer species, P. patulus filtered highest volume (100 μl ind(-1) min(-1) from mixed diets containing higher proportions (50 or 75%) of M. aeruginosa. Thus, there were species-specific differences in the filtration and feeding rates of zooplankton when offered mixed diets of green algae and toxic cyanobacteria. These probably explain the coexistence of different zooplankton species in Microcystis-dominant waterbodies.

  20. Symbiotic bacteria contribute to increasing the population size of a freshwater crustacean, Daphnia magna.

    PubMed

    Peerakietkhajorn, Saranya; Tsukada, Koji; Kato, Yasuhiko; Matsuura, Tomoaki; Watanabe, Hajime

    2015-04-01

    The filter-feeding crustacean Daphnia is a key organism in freshwater ecosystems. Here, we report the effect of symbiotic bacteria on ecologically important life history traits, such as population dynamics and longevity, in Daphnia magna. By disinfection of the daphniid embryos with glutaraldehyde, aposymbiotic daphniids were prepared and cultured under bacteria-free conditions. Removal of bacteria from the daphniids was monitored by quantitative polymerase chain reaction for bacterial 16S rRNA gene. The population of aposymbiotic daphniids was reduced 10-folds compared with that of the control daphniids. Importantly, re-infection with symbiotic bacteria caused daphniids to regain bacteria and increase their fecundity to the level of the control daphniids, suggesting that symbiotic bacteria regulate Daphnia fecundity. To identify the species of symbiotic bacteria, 16S rRNA genes of bacteria in daphniids were sequenced. This revealed that 50% of sequences belonged to the Limnohabitans sp. of the Betaproteobacteria class and that the diversity of bacterial taxa was relatively low. These results suggested that symbiotic bacteria have a beneficial effect on D. magna, and that aposymbiotic Daphnia are useful tools in understanding the role of symbiotic bacteria in the environmental responses and evolution of their hosts.

  1. Absence of sterols constrains carbon transfer between cyanobacteria and a freshwater herbivore (Daphnia galeata).

    PubMed Central

    von Elert, Eric; Martin-Creuzburg, Dominik; Le Coz, Jean R

    2003-01-01

    A key process in freshwater plankton food webs is the regulation of the efficiency of energy and material transfer. Cyanobacterial carbon (C) in particular is transferred very inefficiently to herbivorous zooplankton, which leads to a decoupling of primary and secondary production and the accumulation of cyanobacterial biomass, which is associated with reduced recreational quality of water bodies and hazards to human health. A recent correlative field study suggested that the low transfer efficiency of cyanobacterial C is the result of the absence of long-chain polyunsaturated fatty acids (PUFA) in the diet of the zooplankton. By supplementation of single-lipid compounds in controlled growth experiments, we show here that the low C transfer efficiency of coccal and filamentous cyanobacteria to the keystone herbivore Daphnia is caused by the low sterol content in cyanobacteria, which constrains cholesterol synthesis and thereby growth and reproduction of the herbivore. Estimations of sterol requirement in Daphnia suggest that, when cyanobacteria comprise more than 80% of the grazed phytoplankton, growth of the herbivore may be limited by sterols and Daphnia may subsequently fail to control phytoplankton biomass. Dietary sterols therefore may play a key role in freshwater food webs and in the control of water quality in lakes dominated by cyanobacteria. PMID:12816661

  2. Chronic effects of contaminated sediment on Daphnia magna and Chironomus tentans

    SciTech Connect

    Nebeker, A.V.; Onjukka, S.T.; Cairns, M.A.

    1988-10-01

    Chronic tests were conducted with Daphnia magna (cladoceran) and Chironomus tentans (midge) to determine their usefulness as test organisms for chronic sediment assays, and to estimate the potential long-term impact of contaminated freshwater sediments and contaminated Superfund site soils on freshwater invertebrates. These two species have been used successfully in acute sediment tests, and have been shown to be useful in chronic tests in water--only bioassays.

  3. Chronic effects of contaminated sediment on Daphnia magna and Chironomus tentans (journal version)

    SciTech Connect

    Nebeker, A.V.; Onjukka, S.T.; Cairns, M.A.

    1988-01-01

    Chronic tests were conducted with Daphnia magna (cladoceran) and Chironomus tentans (midge) to determine their usefulness as test organisms for chronic sediment assays, and to estimate the potential long-term impact of contaminated freshwater sediments and contaminated Superfund-site soils on freshwater invertebrates. These two species were used successfully in acute sediment tests and were shown to be useful in chronic tests in water.

  4. Effects of chromium, copper, nickel, and zinc on survival and feeding of the cladoceran Moina macrocopa

    SciTech Connect

    Wong, C.K.

    1992-10-01

    Heavy metals are widely recognized as highly toxic and dangerous. Past research activities on heavy metal pollution in Hong Kong have emphasized coastal environmentals. Since the main sources of heavy metals are the discharge and spillage of wastewater from electroplating factories, concentrations of heavy metals in streams and pools near industrial areas may be higher than those in coastal waters. Electroplating wastewater in Hong Kong contains high levels of chromium, copper, nickel and zinc. The toxicity of these heavy metals to the aquatic organisms has been extensively reviewed. Toxicity information for invertebrates shows that crustaceans are among the most sensitive organisms. Of the crustacean species tested, cladocerans appear to be the most susceptibile. Cladocerans are important components of many aquatic ecosystems. Despite their importance in many freshwater communities and their sensitivity to heavy metal toxicity, information on the toxicity of heavy metals to cladocerans is limited except for several Daphnia species. In Hong Kong the freshwater cladoceran Moina macrocopa occurs in small ponds and rice paddies and is mass cultured by some farmers as a high quality fish food. The objectives of this study are to determine the effects of various heavy metals on the survival and feeding of M. macrocopa. 12 refs., 2 figs., 1 tab.

  5. Effect of the dispersion of oil in freshwater based on time-dependent Daphnia magna toxicity tests

    SciTech Connect

    Vindimian, E.; Vollat, B.; Garric, J. )

    1992-02-01

    The purpose of this work is the study of the time dependence of the acute toxicity of oil and dispersants on a sensitive freshwater organism: Daphnia magna. Two different oils were used: a crude oil from the southwest of France and a gas oil free from volatile substances after being equilibrated with atmosphere. Two commercial dispersants were used: British Petroleum Enersperse 1037 and Dasic Freshwater for this study.

  6. Bacterial epibionts of Daphnia: a potential route for the transfer of dissolved organic carbon in freshwater food webs.

    PubMed

    Eckert, Ester M; Pernthaler, Jakob

    2014-09-01

    The identification of interacting species and elucidation of their mode of interaction may be crucial to understand ecosystem-level processes. We analysed the activity and identity of bacterial epibionts in cultures of Daphnia galeata and of natural daphnid populations. Epibiotic bacteria incorporated considerable amounts of dissolved organic carbon (DOC), as estimated via uptake of tritiated leucine: three times more tracer was consumed by microbes on a single Daphnia than in 1 ml of lake water. However, there was virtually no incorporation if daphnids were anaesthetised, suggesting that their filtration activity was essential for this process. Microbial DOC uptake could predominantly be assigned to microbes that were located on the filter combs of daphnids, where the passage of water would ensure a continuously high DOC supply. Most of these bacteria were Betaproteobacteria from the genus Limnohabitans. Specifically, we identified a monophyletic cluster harbouring Limnohabitans planktonicus that encompassed sequence types from D. galeata cultures, from the gut of Daphnia magna and from daphnids of Lake Zurich. Our results suggest that the epibiotic growth of bacteria related to Limnohabitans on Daphnia spp. may be a widespread and rather common phenomenon. Moreover, most of the observed DOC flux to Daphnia in fact does not seem to be associated with the crustacean biomass itself but with its epibiotic microflora. The unexplored physical association of daphnids with heterotrophic bacteria may have considerable implications for our understanding of carbon transfer in freshwater food webs, that is, a trophic 'shortcut' between microbial DOC uptake and predation by fish.

  7. "In vitro" evaluation of the bacterivore potential of three Cladoceran species occurring in tropical and subtropical regions.

    PubMed

    Hayashi-Martins, L H; Mansano, A S; Hisatugo, K F; Rocha, O; Seleghim, M H R

    2017-03-16

    Cladocerans occupy an important position among the bacterial consumers in freshwater food webs, being relatively non-selective filter feeders that can exert a strong impact on microbial populations. We evaluated the bacterivory potential of three cladocerans species of subtropical and tropical occurrence (Ceriodaphnia silvestrii, Daphnia gessneri and Ceriodaphnia cornuta) at different life stages, by scanning electron microscopy (SEM) and by the quantification of their bacterial consumption rates using fluorescently labeled bacteria (FLB). All species showed filter mesh sizes sufficiently narrow to retain bacteria. The largest distance between setules was found in primiparous C. cornuta, and the smallest in neonate D. gessneri. The lowest ingestion (IR) and removal (RR) rates were observed in primiparous C. silvestrii and the highest values were observed in adults of D. gessneri. We conclude that bacteria may be considered an important food supplement, particularly for neonates who presented smaller intersetular distances and higher filtration rates than the other life stages.

  8. Relationship between solubility and toxicity of coal liquefaction materials to the freshwater crustacean, Daphnia magna

    SciTech Connect

    Dauble, D.D.; Gray, R.H.; Scott, A.J.; Thomas, B.L.

    1985-11-01

    The potential ecological risk from complex coal liquids that may be released to freshwater ecosystems is ultimately dependent on both the degree of solubility of parent material and the toxic properties of constitutent compounds that an organism is exposed to. Thus, highly water-soluble components that remain bioavailable and are present in the water column at acutely toxic concentrations pose a problem for many aquatic organisms. We screened coal liquids derived from several processes and under different process designs to evaluate the acute toxicity of their water-soluble fractions (WSFs) to Daphnia magna. The solubility of materials treated varied and WSFs ranged from 44 to 2260 mg/L total carbon (TC). The most soluble materials in water exhibited greater toxicity based on percent dilution of the WSF. However, toxicity was similar for all materials tested when based on soluble components (TC in solution). Chemical characterization of the WSFs indicated that phenols comprised the majority of the TC in solution. Because toxicity based on total phenols was generally greater than that for individual phenolics tested separately, other soluble chemical classes in the complex mixtures likely contribute to observed toxicity.

  9. Uptake and effects of microplastic textile fibers on freshwater crustacean Daphnia magna.

    PubMed

    Jemec, Anita; Horvat, Petra; Kunej, Urban; Bele, Marjan; Kržan, Andrej

    2016-12-01

    Microplastic fibers (MP) from textile weathering and washing are increasingly being recognized as environmental pollutants. The majority of studies on the bioavailability and effects of microplastic focused on small polystyrene spherical plastic particles, while less data are available for fibers and for other materials besides polystyrene. We investigated the ingestion and effects of ground polyethylene terephthalate (PET) textile microfibers (length range: 62-1400 μm, width 31-528 μm, thickness 1-21.5 μm) on the freshwater zooplankton crustacean Daphnia magna after a 48 h exposure and subsequent 24 h of recovery in MP free medium and algae. The majority of ingested fibers by D. magna were around 300 μm, but also some very large twisted MP fibers around 1400 μm were found inside the gut. Exposure to these fibers results in increased mortality of daphnids after 48 h only in the case where daphnids were not pre-fed with algae prior to experiment, but no effect was found when daphnids were fed before the experiments. Regardless of the feeding regime, daphnids were not able to recover from MP exposure after additional 24 h incubation period in a MP free medium with algae. The uptake and effects of PET textile MP on D. magna are presented here for the first time.

  10. Effect of copper contaminated food on the life cycle and secondary production of Daphnia laevis.

    PubMed

    Rocha, Giseli S; Tonietto, Alessandra E; Lombardi, Ana T; Melão, Maria da G G

    2016-11-01

    In aquatic environments, copper (Cu) plays important physiological roles in planktonic food chain, such as electron transfer in photosynthesis and constituting proteins that transport oxygen in some arthropods, while at higher concentrations it is toxic on these organisms and higher trophic levels. The combined effects of natural (e.g. volcanic activity) and anthropogenic sources (e.g. mining waste) contribute to the increase in copper pollution in different ecosystems and regions around the world. In the present study, we evaluated the bioaccumulation and effect of Cu on Raphidocelis subcapitata (freshwater algae), and the influence of Cu-contaminated food (algae) on Daphnia laevis (tropical cladoceran). The amount of copper accumulated in microalgae and cladoceran was quantified, and life-history parameters of D. laevis such as growth, reproduction and longevity were measured. The cell density of Cu exposed R. subcapitata declined, and cladoceran fed with contaminated food had lower longevity, production of eggs and neonates, and reduced secondary production. A concentration dependent increase in Cu accumulation was observed in the microalgae, while the opposite occurred in the animal, indicating a cellular metal regulatory mechanism in the latter. However, this regulation seems not to be sufficient to avoid metal induced damages in the cladoceran such as decreased longevity and reproduction. We conclude that diet is an important metal exposure route to this cladoceran, and the assessment of chronic contamination during the complete life cycle of cladoceran provides results that are similar to those observed in natural environments, especially when native organisms are investigated.

  11. Dormant Progagule Banks of Cladoceran Communites and Hatching Success from the Sedimentin China

    NASA Astrophysics Data System (ADS)

    Zhu, Chi; Wang, Shui; Kong, Fan-xiang

    2017-01-01

    The resources of cladoceran communitesin lakes in typical eutrophic shallow lakes in Chinawere investigated. Diapausing eggs of cladocerans were collected from the surface sediment of typical eutrophic shallow lakes and then hatched in the laboratory. The most common and dominant genera were Bosmina sp., Ceriodaphnia sp., Alona sp. and Moina sp. The density of large cladocerans in the hatchlings was lower than the small cladocerans (Bosmina, Ceriodaphnia, Alonaand Moina). The distribution and abundance and species of Daphnia community were significantly influenced by TN and fish community.

  12. Free ionic nickel accumulation and localization in the freshwater zooplankter, Daphnia magna

    SciTech Connect

    Hall, T.M.

    1982-01-01

    The processes which lead to the accumulation of free ionic nickel (radioactive) from solution by Daphnia magna were studied and incorporated into a model which describes accummulation at different concentrations. Adsorption proved to be a relatively small component of nickel accummulation. The accummulation rate eventually approached zero, which represented an equilibrium between uptake and loss of nickel. However, elimination experiments did reveal a pool of relatively static nickel. The appearance and distribution of nickel within five body parts (body fluid, carapace, gut, filtering appendages, and eggs) of D. magna supported the accummulation data and added to the understanding of the pathways of nickel through the organism.

  13. Sensitivity of Daphnia species to phosphorus-deficient diets.

    PubMed

    Seidendorf, Bernd; Meier, Nadine; Petrusek, Adam; Boersma, Maarten; Streit, Bruno; Schwenk, Klaus

    2010-02-01

    The life history of freshwater cladocerans such as Daphnia spp. is strongly affected by their environment. Factors such as temperature, food quantity and even the presence or absence of predators influence growth, reproduction and morphology of individuals. Recently, it has also become clear that the quality of the food can affect various life history traits of Daphnia. More specifically, the effect of the elemental composition of algae, expressed as the C:P ratio, has been studied intensively. Daphnia species differ in their response to differences in the C:P ratio of their food. Until now, it has been unclear whether these species differences are driven by phylogenetic constraints or by adaptation to particular environmental conditions. Here we present laboratory experiments with 12 Daphnia species from three different subgenera originating from a broad range of habitats. We compared somatic growth rates and sensitivity to variation in the nutrient stoichiometry of the food with habitat parameters, taking into account the phylogenetic history of the species. No associations between fitness and habitat parameters were detected. However, we found a trade-off between sensitivity to P-deficient diets and the maximum growth rate on a P-sufficient diet. In several cases, this trade-off helps to explain the association between species distribution and habitat parameters. We observed no correlation of the sensitivity to P limitation with the phylogenetic history of the genus Daphnia. Thus, we conclude that the differential responses among Daphnia species to variation in P content in food were driven mainly by adaptations to their local habitats, and are not constrained by deep evolutionary patterns.

  14. Toxicity of soybean rust fungicides to freshwater algae and Daphnia magna.

    PubMed

    Ochoa-Acuña, Hugo G; Bialkowski, Walter; Yale, Gowri; Hahn, Leighanne

    2009-05-01

    Soybeans are intensively grown over large swaths of land in the Midwestern US. Introduction of the pathogenic fungus responsible for Soybean Rust (Phakopsora pachyrhizi) will likely result in a significant increase in the environmental load of strobilurin and conazole fungicides. We determined the toxicity of six such fungicides to the unicellular algae Pseudokirchneriella subcapitata and the aquatic invertebrate, Daphnia magna. We found that levels of concern of some fungicides were lower than annual average runoff concentrations predicted for Indiana. Our results suggest that pyraclostrobin and propiconazole, and to a lesser extent tebuconazole, may cause impacts to algae and daphnids in areas where soybeans are intensively grown. More studies are needed to describe the ecological effects of sublethal exposures to these fungicides, as well as monitoring environmental concentrations in watersheds where these fungicides are applied to soybeans.

  15. In vivo biodegradation of colloidal quantum dots by a freshwater invertebrate, Daphnia magna.

    PubMed

    Kwon, Dongwook; Kim, Min Jung; Park, Chansik; Park, Jaehong; Choi, Kyungho; Yoon, Tae Hyun

    2012-06-15

    Impacts of planktonic invertebrate, Daphnia magna, on the speciation of colloidal quantum dots (QD) were investigated using fluorescence spectromicroscopic technique. Well-dispersed (GA/TOPO)QD were prepared by forming a supramolecular assembly of hydrophobic (TOPO)QD with biomacromolecules (i.e., Gum Arabic, GA). Biological degradation of this nanomaterial was monitored by fluorescence spectromicroscopic methods. Our study confirmed the major uptake pathway of manufactured nanomaterials and in vivo biodegradation processes in a well-known toxicity test organism, D. magna. In addition, we also found that D. magna can induce significant deterioration of aquatic media by releasing fragments of partially degraded QD colloids. These biological processes may significantly change the predicted toxicities of nanomaterials in aquatic environments. Thus, we propose that the impacts of aquatic living organisms on the environmental fate of manufactured nanomaterials (MNs) should be carefully taken into account when assessing the risk of MNs to the environment and human health.

  16. Survival of daphnia magna and hyalella azteca in cadmium-spiked water and sediment

    SciTech Connect

    Nebeker, A.V.; Onjukka, S.T.; Cairns, M.A.; Krawczyk, D.F.

    1986-01-01

    Freshwater sediments and water were spiked with cadmium (Cd) in the laboratory, and toxicity tests were conducted with the cladoceran Daphnia magna and the amphipod Hyalella azteca to determine if Cd in the sediment would cause increased toxicity. The 48-h LC50 values for Daphnia in tests without sediment were 36, 33, 24, and 40 micrograms/L total Cd. Calculated free-ion (Cd/sup 2 +/)LC50 values for the same tests were 28, 25, 18 and 31 micrograms/L. LC50 values (48-h) determined for total Cd(uncentrifuged water sample) in the sediment-containing beakers were 252, 69, and 122 micrograms/L for Daphnia. LC50 values for dissolved Cd(centrifuged 10,000 rpm) in the sediment-containing beakers were 61, 27, and 100 micrograms/L for Daphnia. Higher total Cd LC50 values indicate that Cd adsorbed to soluble organic material was not biologically available. No significant mortality of Daphnia or Hyalella occurred in the flow-through tests in which sediment contained the same levels of Cd as in the static tests. Mortality was similar in beakers with and without Cd-spiked sediment, indicating that Cd in the sediment and adsorbed to organic materials was not available to cause increased mortality.

  17. Correlation between heavy metal acute toxicity values in Daphnia magna and fish

    SciTech Connect

    Khangarot, B.S.; Ray, P.K.

    1987-04-01

    In the toxicant bioassays, invertebrates with special reference to aquatic arthropod species have been of recent interest as test models due to the need for developing nonmammalian tests system. The cladoceran Daphnia magna bioassays have several practical advantages. D. magna has been used as a useful test species and its sensitivity to environmental pollutants have been recognized as a general representative of other freshwater zooplankton species. The objectives of this study were to determine the acute toxicity of various heavy metals to Daphnia magna for 48 h of exposure and to compare these values with the existing LC50 values for rainbow trout (Salmo gairdneri); which is commonly used as a test animal in aquatic bioassay studies.

  18. Effects of food availability on the acute and chronic toxicity of the insecticide methomyl to Daphnia spp.

    PubMed

    Pereira, Joana Luísa; Gonçalves, Fernando

    2007-11-01

    The widespread increase of pesticides application in crops threats vicinal freshwater lentic ecosystems, frequently leading to their contamination. Due to their position in the aquatic food web, the responses to these pesticide inputs of freshwater filter-feeding zooplankters, as daphnids, provide relevant information the general risk to the ecosystem of xenobiotics. Moreover, cladoceran grazers often face fluctuations in food availability due to the phytoplankton dynamics in lentic water bodies, and food acquisition naturally conditions their fitness. In this study, the responses of Daphnia magna, and of three genotypes within the Daphnia longispina complex, to acute and chronic exposures of methomyl, were assessed. In addition, we focused on whether the food level can model the Daphnia life-history responses to the insecticide. Results showed that methomyl was acutely and chronically toxic to both D. magna and the D. cf longispina populations at very low concentrations, and remarkable differences in sensitivity were noticed when comparing the responses to the toxic among taxa/genotypes. Furthermore, food availability conditioned the overall fitness of the species although not interacting specifically on the response to the toxicant stress.

  19. Production and release of cyclic AMP by Daphnia pulex: implications of grazing activity

    SciTech Connect

    Francko, D.A.; Wetzel, R.G.

    1982-04-01

    Daphnia pulex, a common cladoceran zooplankton species, contains tissue cAMP concentrations similar to those found in algae, bacteria, and aquatic macrophytes. Daphnia release significant quantities of cAMP into the extracellular medium. Release of algal cellular cAMP as a result of digstive degradation of algal cells may also be an important source of dissolved cAMP in lakewater.

  20. Production and release of cyclic AMP by Daphnia pulex: implications of grazing activity

    SciTech Connect

    Francko, D.A.; Wetzel, R.G.

    1982-04-01

    Daphnia pulex, a common cladoceran zooplankton species, contains tissue cAMP concentrations similar to those found in algae, bacteria, and aquatic macrophytes. Daphnia release significant quantities of cAMP into the extracellular medium. Release of algal cellular cAMP as a result of digestive degradation of algal cells may also be an important source of dissolved cAMP in lakewater.

  1. Retroconversion of docosapentaenoic acid (n-6): an alternative pathway for biosynthesis of arachidonic acid in Daphnia magna.

    PubMed

    Strandberg, Ursula; Taipale, Sami J; Kainz, Martin J; Brett, Michael T

    2014-06-01

    The aim of this study was to assess metabolic pathways for arachidonic acid (20:4n-6) biosynthesis in Daphnia magna. Neonates of D. magna were maintained on [(13)C] enriched Scenedesmus obliquus and supplemented with liposomes that contained separate treatments of unlabeled docosapentaenoic acid (22:5n-6), 20:4n-6, linoleic acid (18:2n-6) or oleic acid (18:1n-9). Daphnia in the control treatment, without any supplementary fatty acids (FA) containing only trace amounts of 20:4n-6 (~0.3% of all FA). As expected, the highest proportion of 20:4n-6 (~6.3%) was detected in Daphnia that received liposomes supplemented with this FA. Higher availability of 18:2n-6 in the diet increased the proportion of 18:2n-6 in Daphnia, but the proportion of 20:4n-6 was not affected. Daphnia supplemented with 22:5n-6 contained ~3.5% 20:4n-6 in the lipids and FA specific stable isotope analyses validated that the increase in the proportion of 20:4n-6 was due to retroconversion of unlabeled 22:5n-6. These results suggest that chain shortening of 22:5n-6 is a more efficient pathway to synthesize 20:4n-6 in D. magna than elongation and desaturation of 18:2n-6. These results may at least partially explain the discrepancies noticed between phytoplankton FA composition and the expected FA composition in freshwater cladocerans. Finally, retroconversion of dietary 22:5n-6 to 20:4n-6 indicates Daphnia efficiently retain long chain n-6 FA in lake food webs, which might be important for the nutritional ecology of fish.

  2. BIOENERGETICS OF A SEMI-TROPICAL CLADOCERAN, DAPHNIA LUMHOLTZI

    EPA Science Inventory

    The bioenergetics of D.lumholtzi from Kentucky Lake, USA was investigated across a wide range of temperatures and food concentrations...This suggests a physiological adaptation to competitive ability under differing climatic conditions.

  3. Hormonal induction of undescribed males resolves cryptic species of cladocerans.

    PubMed

    Kim, Keonho; Kotov, Alexey A; Taylor, Derek J

    2006-01-22

    Cyclic parthenogens have a mixed breeding system with both meiotic and ameiotic eggs. Although investment in sexual stages is often synchronized with seasonal cycles, the degree of investment is a quantitative trait associated with habitat instability. Populations of cyclic parthenogens from stable environments, such as large lakes and oceans, generally show reduced or undetectable investment in males. Indeed, males of many species of lacustrine cyclic parthenogens are unknown to science. Methyl farnesoate (MF), a crustacean juvenile hormone, has been implicated as an inducer of male formation in Daphnia magna (Crustacea: Cladocera), a denizen of unstable habitats with marked sexual recruitment. Here, we show experimentally that MF induces male production in four distantly related lacustrine species of cladocerans under growth conditions unfavourable for male production. The males of three species are new to science. Unlike females, the anatomy of the previously unknown males of Bosmina (Lunobosmina) oriens permitted ready morphological diagnosis of sibling species and subfossils. The results suggest that the role for MF in the sex determination of cladocerans is general.

  4. Morphology of the Daphnia nervous system: a comparative study on Daphnia pulex, Daphnia lumholtzi, and Daphnia longicephala.

    PubMed

    Weiss, Linda C; Tollrian, Ralph; Herbert, Zsofia; Laforsch, Christian

    2012-12-01

    The freshwater crustacean Daphnia is well known for its phenotypic plasticity, in which environmental cues are perceived by the nervous system and transformed into phenotypic adaptations beneficial under current conditions. Critical knowledge regarding the distribution and localization of neuronal antigens or neurotransmitters and differentially expressed proteins is sparse. Here, we applied immunohistochemical and histological-staining methods in combination with confocal laser scanning microscopy on whole mount preparations in Daphnia pulex, Daphnia longicephala, and Daphnialumholtzi. We document the nervous system, elements of the sensory system, and cell clusters with secretory characteristics in the Daphnia head. This is the first report on the nervous system of the species D.longicephala and D.lumholtzi. The methods established in this investigation will help to foster research on specific neuronal mechanisms in this rapidly advancing model system of life science research.

  5. A novel apparatus for evaluating contaminant effects on feeding activity and heart rate in Daphnia spp.

    PubMed

    Lari, Ebrahim; Steinkey, Dylan; Pyle, Greg G

    2017-01-01

    Cladoceran are animals of significant importance to freshwater bodies such that changes in their populations may result in drastic shifts in the food web. Numerous studies have investigated the effects of toxicants, and the effects of chemical and physical habitat changes to these animals. Most of these studies investigated more general endpoints such as mortality, reproduction, growth, and food consumption over time, and less frequently examined molecular endpoints such as enzyme activity or gene expression. However, behavioral and physiological endpoints that link the organism and molecular level endpoints are scarce. In this study, we designed an apparatus that allows for the simultaneous investigation of three essential behavioral and physiological endpoints in Daphnia, including ventilation, food uptake rate, and heart rate. Using our apparatus, we studied the effect of cadmium (Cd), suspended particles, and food on the beating rate of thoracic limbs and the frequency of mandible rolling in Daphnia magna. We also studied the effect of temperature on the heart and thoracic limb beat frequency. The results show that both Cd and suspended particles reduce the activity of mandibles and thoracic limbs. Thoracic limb movements and heart rate increased gradually with temperature. Our toxicity tests show that changes in feeding, ventilation, and heart rate are easily detected using this method.

  6. Reproductive switching analysis of Daphnia similoides between sexual female and parthenogenetic female by transcriptome comparison

    PubMed Central

    Zhang, Ya-Nan; Zhu, Xiu-Yun; Wang, Wen-Ping; Wang, Yi; Wang, Lu; Xu, Xiao-Xue; Zhang, Kun; Deng, Dao-Gui

    2016-01-01

    The water flea Daphnia are planktonic crustaceans commonly found in freshwater environment that can switch their reproduction mode from parthenogenesis to sexual reproduction to adapt to the external environment. As such, Daphnia are great model organisms to study the mechanism of reproductive switching, the underlying mechanism of reproduction and development in cladocerans and other animals. However, little is known about the Daphnia’s reproductive behaviour at a molecular level. We constructed a genetic database of the genes expressed in a sexual female (SF) and a parthenogenetic female (PF) of D. similoides using Illumina HiSeq 2500. A total of 1,763 differentially expressed genes (865 up- and 898 down-regulated) were detected in SF. Of the top 30 up-regulated SF unigenes, the top 4 unigenes belonged to the Chitin_bind_4 family. In contrast, of the top down-regulated SF unigenes, the top 3 unigenes belonged to the Vitellogenin_N family. This is the first study to indicate genes that may have a crucial role in reproductive switching of D. similoides, which could be used as candidate genes for further functional studies. Thus, this study provides a rich resource for investigation and elucidation of reproductive switching in D. similoides. PMID:27671106

  7. Contribution of cyclic parthenogenesis and colonization history to population structure in Daphnia.

    PubMed

    Thielsch, Anne; Brede, Nora; Petrusek, Adam; de Meester, Luc; Schwenk, Klaus

    2009-04-01

    Cyclic parthenogenesis, the alternation of parthenogenetic and sexual reproduction, can lead to a wide scope of population structures, ranging from almost monoclonal to genetically highly diverse populations. In addition, sexual reproduction in aquatic cyclic parthenogens is associated with the production of dormant stages, which both enhance potential gene flow among populations as well as impact local evolutionary rates through the formation of dormant egg banks. Members of the cladoceran genus Daphnia are widely distributed key organisms in freshwater habitats, which mostly exhibit this reproduction mode. We assessed patterns of genetic variation within and among populations in the eurytopic and morphologically variable species Daphnia longispina, using data from both nuclear (13 microsatellite loci) and mitochondrial (partial sequencing of the 12S rRNA gene) markers from a set of populations sampled across Europe. Most populations were characterized by very high clonal diversity, reflecting an important impact of sexual reproduction and low levels of clonal selection. Among-population genetic differentiation was very high for both nuclear and mitochondrial markers, and no strong pattern of isolation by distance was observed. We also did not observe any substantial genetic differentiation among traditionally recognized morphotypes of D. longispina. Our findings of high levels of within-population genetic variation combined with high among-population genetic differentiation are in line with predictions of the monopolization hypothesis, which suggests that in species with rapid population growth and potential for local adaptation, strong priority effects due to monopolization of resources lead to reduced levels of gene flow.

  8. Differences in susceptibility of five cladoceran species to two systemic insecticides, imidacloprid and fipronil.

    PubMed

    Hayasaka, Daisuke; Korenaga, Tomoko; Suzuki, Kazutaka; Sánchez-Bayo, Francisco; Goka, Koichi

    2012-03-01

    Differences in susceptibility of five cladocerans to the neonicotinoid imidacloprid and the phenyl-pyrazole fipronil, which have been dominantly used in rice fields of Japan in recent years, were examined based on short-term (48-h), semi-static acute immobilization exposure tests. Additionally, we compared the species sensitivity distribution (SSD) patterns of both insecticides between two sets of species: the five tested cladocerans and all other aquatic organisms tested so far, using data from the ECOTOX database of U.S. Environmental Protection Agency (USEPA). The sensitivity of the test species to either imidacloprid or fipronil was consistent, spanning similar orders of magnitude (100 times). At the genus level, sensitivities to both insecticides were in the following descending order: Ceriodaphnia > Moina > Daphnia. A positive relationship was found between body lengths of each species and the acute toxicity (EC(50)) of the insecticides, in particular fipronil. Differences in SSD patterns of imidacloprid were found between the species groups compared, indicating that test cladocerans are much less susceptible than other aquatic species including amphibians, crustaceans, fish, insects, mollusks and worms. However, the SSD patterns for fipronil indicate no difference in sensitivity between cladocerans tested and other aquatic organisms despite the greater exposure, which overestimates the results, of our semi-static tests. From these results, Ceriodaphnia sp. should be considered as more sensitive bioindicators (instead of the standard Daphnia magna) for ecotoxicological assessments of aquatic ecosystems. In addition, we propose that ecotoxicity data associated with differences in susceptibility among species should be investigated whenever pesticides have different physicochemical properties and mode of action.

  9. Comet Assay on Daphnia magna in eco-genotoxicity testing.

    PubMed

    Pellegri, Valerio; Gorbi, Gessica; Buschini, Annamaria

    2014-10-01

    Detection of potentially hazardous compounds in water bodies is a priority in environmental risk assessment. For the evaluation and monitoring of water quality, a series of methodologies may be applied. Among them, the worldwide used toxicity tests with organisms of the genus Daphnia is one of the most powerful. In recent years, some attempts were made to utilize Daphnia magna in genotoxicity testing as many of the new environmental contaminants are described as DNA-damaging agents in aquatic organisms. The aim of this research was to develop a highly standardized protocol of the Comet Assay adapted for D. magna, especially regarding the isolation of cells derived from the same tissue (haemolymph) from newborn organisms exposed in vivo. Several methods for haemolymph extraction and different Comet Assay parameters were compared. Electrophoretic conditions were adapted in order to obtain minimum DNA migration in cells derived from untreated organisms and, at the same time, maximum sensitivity in specimens treated with known genotoxicants (CdCl2 and H2O2). Additional tests were performed to investigate if life-history traits of the cladoceran (such as the age of adult organisms that provide newborns, the clutch size of origin, the number of generations reared in standard conditions) and the water composition as well, might influence the response of the assay. This study confirms the potential application of the Comet Assay in D. magna for assessing genotoxic loads in aqueous solution. The newly developed protocol could integrate the acute toxicity bioassay, thus expanding the possibility of using this model species in freshwater monitoring (waters, sediment and soil elutriates) and is in line with the spirit of the EU Water Framework Directive in reducing the number of bioassays that involve medium-sized species.

  10. Aquatic toxicity of cartap and cypermethrin to different life stages of Daphnia magna and Oryzias latipes.

    PubMed

    Kim, Younghee; Jung, Jinyong; Oh, Sorin; Choi, Kyungho

    2008-01-01

    Cartap and cypermethrin, which are among the most widely used pesticides in many countries, are considered safe because of their low mammalian toxicity and their low persistence in the environment. However, recent findings of endocrine-disrupting effects and developmental neurotoxicity have raised concerns about the potential ecological impacts of these pesticides. We evaluated the aquatic toxicity of cartap [S,S'-(2-dimethylaminotrimethylene) bis(thiocarbamate), unspecified hydrochloride] and cypermethrin [(RS)-alpha-cyano-3-phenoxybenzyl-(1RS,3RS,1RS,3SR)-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylate], both individually and combined, on different life stages of the freshwater cladoceran Daphnia magna and a freshwater teleost, Japanese medaka (Oryzias latipes). The 96-hr Daphnia median effective concentrations (EC50s) for cartap and cypermethrin were 91.0 microg/L and 0.00061 microg/L, respectively. Rapid recovery of Daphnia was observed after short-term pulsed exposure to cartap and cypermethrin; there were no adverse effects on reproduction or survival 20 d after a 24 hr exposure to cartap up to 1240 microg/L and cypermethrin up to 1.9 microg/L. Chronic continuous exposure (for 21 d) of 7-d-old Daphnia to cypermethrin significantly reduced the intrinsic population growth rate in a concentration-dependent manner. However, because the intrinsic population growth rates were all above zero, populations did not decrease even at the highest experimental concentration of 200 ng/L. Exposure of Daphnia neonates (< 24 hr old) to cypermethrin for 21 d caused significant, sub-lethal reproduction-related problems, such as increased time to first brood, reduced brood size, and reduced total brood number, at 0.0002, 0.002, and 0.2 ng/L cypermethrin, but the intrinsic population growth rate was not significantly affected. Oryzias latipes was relatively more resistant to both pesticides. In particular, embryos appeared to be more resistant than juveniles or adults

  11. The effects of ultraviolet-B radiation on freshwater invertebrates: Experiments with a solar simulator

    USGS Publications Warehouse

    Hurtubise, R.D.; Havel, J.E.; Little, E.E.

    1998-01-01

    There is concern that decreases in stratospheric ozone will lead to hazardous levels of ultraviolet-B (UV-B) radiation at the Earth's surface. In clear water, UV-B may penetrate to significant depths. The purpose of the current study was to compare the sensitivity of freshwater invertebrates to UV-B. We used a solar simulator, calibrated to match local ambient solar radiation, to expose five species of freshwater invertebrates to enhanced levels of UV-B radiation. UV-B measurements in a eutrophic pond revealed that 10% of the irradiance penetrated to 30-cm depth and 1% to 57-cm depth. The irradiance at the upper 5-20 cm was comparable to levels used in the simulator. Median lethal dose (LD50) values were determined for the cladocerans Ceriodaphnia reticulata, Scapholeberis kingii (two induced color morphs), and Daphnia magna; the ostracod Cyprinotus incongruens; and the amphipod Hyalella azteca. Among the species, 96-h LD50 estimates were quite variable, ranging from 4.2 to 84.0 ??W cm-2. These estimates indicated S. kingii to be highly sensitive and H. azteca, C. reticulata, and D. magna to be moderately sensitive, whereas the ostracod C. incongruens was very tolerant to UV-B radiation. Overall, this study suggests that, in shallow ponds without physical refuges, UV-B radiation would have the strongest effects upon cladocerans and amphipods occurring in the water column, whereas ostracods would be better protected.

  12. Tolerance to Copper and to Salinity in Daphnia longispina: Implications within a Climate Change Scenario

    PubMed Central

    Leitão, João; Ribeiro, Rui; Soares, Amadeu M. V. M.; Lopes, Isabel

    2013-01-01

    Considering IPPC climate change scenarios, it is pertinent to predict situations where coastal ecosystems already impacted with chemical contamination became exposed to an additional stressor under a future scenario of seawater intrusion. Accordingly, the present study aimed at evaluating if a negative association between tolerance to a metal and to saltwater exists among genotypes of a freshwater organism. For this, five clonal lineages of the cladoceran Daphnia longispina O.F. Müller, exhibiting a differential tolerance to lethal levels of copper, were selected. Each clonal lineage was exposed to lethal and sublethal concentrations of sodium chloride (assumed as a protective surrogate to evaluate the toxicity of increased salinity to freshwater organisms). Mortality, time to release the first brood and total number of neonates per female were monitored and the somatic growth rate and intrinsic rate of natural increase were computed for each clonal lineage. Data here obtained were compared with their lethal responses to copper and significant negative correlations were found. These results suggest that genetically eroded populations of D. longispina, due to copper or salinity, may be particularly susceptible to a later exposure to the other contaminant supporting the multiple stressors differential tolerance. PMID:23990877

  13. Tolerance to copper and to salinity in Daphnia longispina: implications within a climate change scenario.

    PubMed

    Leitão, João; Ribeiro, Rui; Soares, Amadeu M V M; Lopes, Isabel

    2013-01-01

    Considering IPPC climate change scenarios, it is pertinent to predict situations where coastal ecosystems already impacted with chemical contamination became exposed to an additional stressor under a future scenario of seawater intrusion. Accordingly, the present study aimed at evaluating if a negative association between tolerance to a metal and to saltwater exists among genotypes of a freshwater organism. For this, five clonal lineages of the cladoceran Daphnia longispina O.F. Müller, exhibiting a differential tolerance to lethal levels of copper, were selected. Each clonal lineage was exposed to lethal and sublethal concentrations of sodium chloride (assumed as a protective surrogate to evaluate the toxicity of increased salinity to freshwater organisms). Mortality, time to release the first brood and total number of neonates per female were monitored and the somatic growth rate and intrinsic rate of natural increase were computed for each clonal lineage. Data here obtained were compared with their lethal responses to copper and significant negative correlations were found. These results suggest that genetically eroded populations of D. longispina, due to copper or salinity, may be particularly susceptible to a later exposure to the other contaminant supporting the multiple stressors differential tolerance.

  14. Effects of millimeter wave carbon fibers on filter-feeding freshwater invertebrates.

    PubMed

    Soucek, David J; Dickinson, Amy; Cropek, Donald M

    2010-05-01

    The purpose of our study was to investigate the sub-lethal effects of millimeter wave carbon fibers (MWCF), a military obscurant, on filter-feeding freshwater invertebrates. We observed decreased survival, reproduction, and oxygen consumption in Daphnia magna at realistic loading rates. In experiments with the Asiatic clam (Corbicula fluminea), soft tissue dry weight and tissue condition index were not significantly different among control and MWCF exposed treatments; however, using a (15)N labeled alga as food, we observed decreased nitrogen turnover in tissues of clams exposed to MWCF, suggesting lower filtering or ingestion rates. Our findings combined with previous demonstrations of MWCF toxicity to green algae suggest that over a period of several months, bivalve growth may be inhibited, and cladoceran populations may be even more strongly affected by MWCF. Given that these fibers are persistent, further experiments should be conducted to determine the longer-term effects of contamination of water bodies with MWCF.

  15. Physiological responses of Daphnia pulex to acid stress

    PubMed Central

    Weber, Anna K; Pirow, Ralph

    2009-01-01

    Background Acidity exerts a determining influence on the composition and diversity of freshwater faunas. While the physiological implications of freshwater acidification have been intensively studied in teleost fish and crayfish, much less is known about the acid-stress physiology of ecologically important groups such as cladoceran zooplankton. This study analyzed the extracellular acid-base state and CO2 partial pressure (PCO2), circulation and ventilation, as well as the respiration rate of Daphnia pulex acclimated to acidic (pH 5.5 and 6.0) and circumneutral (pH 7.8) conditions. Results D. pulex had a remarkably high extracellular pH of 8.33 and extracellular PCO2 of 0.56 kPa under normal ambient conditions (pH 7.8 and normocapnia). The hemolymph had a high bicarbonate concentration of 20.9 mM and a total buffer value of 51.5 meq L-1 pH-1. Bicarbonate covered 93% of the total buffer value. Acidic conditions induced a slight acidosis (ΔpH = 0.16–0.23), a 30–65% bicarbonate loss, and elevated systemic activities (tachycardia, hyperventilation, hypermetabolism). pH 6.0 animals partly compensated the bicarbonate loss by increasing the non-bicarbonate buffer value from 2.0 to 5.1 meq L-1 pH-1. The extracellular PCO2 of pH 5.5 animals was significantly reduced to 0.33 kPa, and these animals showed the highest tolerance to a short-term exposure to severe acid stress. Conclusion Chronic exposure to acidic conditions had a pervasive impact on Daphnia's physiology including acid-base balance, extracellular PCO2, circulation and ventilation, and energy metabolism. Compensatory changes in extracellular non-bicarbonate buffering capacity and the improved tolerance to severe acid stress indicated the activation of defense mechanisms which may result from gene-expression mediated adjustments in hemolymph buffer proteins and in epithelial properties. Mechanistic analyses of the interdependence between extracellular acid-base balance and CO2 transport raised the question of

  16. Comparative population growth of Ceriodaphnia dubia and Daphnia pulex (Cladocera) exposed to zinc toxicity.

    PubMed

    Sanchez-Ortiz, Jonathan Raul; Sarma, S S S; Nandini, S

    2010-01-01

    Population growth of two cladocerans (Ceriodaphnia dubia and Daphnia pulex) exposed to 4 different concentrations of ZnCl(2) (0.125, 0.25, 0.5 and 1.0 mg L(-1), plus controls) at one algal food (Scenedesmus acutus) density (0.5 X 10(6) cells mL(-1)) was quantified for 30 days. Population densities of C. dubia and D. pulex decreased with increasing concentration of Zn in the medium. At a concentration of 1 mg L(-1) of ZnCl(2), both C. dubia and D. pulex did not reproduce and died within a week. The peak population densities of C. dubia ranged from 0.2 to 6.0 ind. mL(-1), depending on the Zn level in the medium, whereas this range was lower for D. pulex (0.2 to 4.1 ind. mL(-1)). The peak population density was inversely related to the Zn concentration. The rate of population increase (r) varied from -0.12 to +0.14 and -0.02 to +0.23 per day for C. dubia and D. pulex, respectively, depending on the Zn level in the medium. Statistically, both the peak population density and the r were significantly affected by the heavy metal concentration in the medium. Multiple comparison tests showed that the rate of population increase (r) of D. pulex in the lowest ZnCl(2) level (0.125 mg L(-1)) was significantly higher than controls. However, under similar conditions, the r of C. dubia was significantly lower than controls. With a further increase in Zn level, the growth rates of both the cladoceran species were significantly reduced as compared to controls. The results are discussed in relation to published data on the toxicity of zinc to freshwater zooplankton.

  17. The use of freshwater and saltwater animals to distinguish between the toxic effects of salinity and contaminants in irrigation drain water

    USGS Publications Warehouse

    Ingersoll, Christopher G.; Dwyer, F.J.; Burch, S.A.; Nelson, M.K.; Buckler, D.R.; Hunn, J.B.

    1992-01-01

    Irrigation drain waters entering Stillwater Wildlife Management Area (SWMA) in south-western Nevada contain elevated levels of salinity and several inorganic contaminants (As, B, Cu, Li, Mo, and Sr). Mortalities of fish and waterfowl at the management area are believed to be associated with the poor water quality of the drains. The objective of the present study was to use fresh-water and saltwater animals to distinguish between the toxic effects of salinity and contaminants in effluent samples collected from irrigation drain waters. Static acute effluent tests were conducted with water collected from four sites at SWMA. Animals acclimated or cultured in fresh water (fathead minnows, Pimephales promelas; amphipods, Hyalella azteca; cladocerans, Daphnia magna) and salt water (striped bass, Morone saxatilis; amphipods, Hyalella azteca; and cladocerans, Daphnia magna) were used to separate toxic effects of salinity from the effects of inorganic contaminants in the drain water. One drain water (TJ drain, salinity 19 parts per thousand (grams per liter), osmolality 503 mmol/kg, hardness 3,780 mg/L as CaCO3) was toxic only to freshwater animals and saltwater cultured daphnids; water from a receiving pond (Pintail Bay, salinity 23 g/L, osmolality 542 mmol/kg, hardness 830 mg/L as CaCO3) was toxic to both freshwater and saltwater animals. Acute tests conducted with reconstituted waters representative of the Pintail Bay sample indicated that atypical ion ratios were toxic to striped bass and amphipods, even without the addition of inorganic contaminants. However, the addition of inorganic contaminants representative of the Pintail Bay sample increased the toxicity of this reconstituted water. These findings indicate that the toxicity of the TJ drain sample was related mainly to elevated salinity and that the toxicity of the Pintail Bay sample was a function of inorganic contamination and atypical ion ratios in combination with elevated salinity.

  18. Toxic effects of chemical dispersant Corexit 9500 on water flea Daphnia magna.

    PubMed

    Toyota, Kenji; McNabb, Nicole A; Spyropoulos, Demetri D; Iguchi, Taisen; Kohno, Satomi

    2017-02-01

    In 2010, approximately 2.1 million gallons of chemical dispersants, mainly Corexit 9500, were applied in the Gulf of Mexico to prevent the oil slick from reaching shorelines and to accelerate biodegradation of oil during the Deepwater Horizon oil spill. Recent studies have revealed toxic effects of Corexit 9500 on marine microzooplankton that play important roles in food chains in marine ecosystems. However, there is still little known about the toxic effects of Corexit 9500 on freshwater zooplankton, even though oil spills do occur in freshwater and chemical dispersants may be used in response to these spills. The cladoceran crustacean, water flea Daphnia magna, is a well-established model species for various toxicological tests, including detection of juvenile hormone-like activity in test compounds. In this study, we conducted laboratory experiments to investigate the acute and chronic toxicity of Corexit 9500 using D. magna. The acute toxicity test was conducted according to OECD TG202 and the 48 h EC50 was 1.31 ppm (CIs 0.99-1.64 ppm). The reproductive chronic toxicity test was performed following OECD TG211 ANNEX 7 and 21 days LOEC and NOEC values were 4.0 and 2.0 ppm, respectively. These results indicate that Corexit 9500 has toxic effects on daphnids, particularly during the neonatal developmental stage, which is consistent with marine zooplankton results, whereas juvenile hormone-like activity was not identified. Therefore, our findings of the adverse effects of Corexit 9500 on daphnids suggest that application of this type of chemical dispersant may have catastrophic impacts on freshwater ecosystems by disrupting the key food chain network. Copyright © 2016 John Wiley & Sons, Ltd.

  19. Chronic toxicity of silver nitrate to Ceriodaphnia dubia and Daphnia magna, and potential mitigating factors.

    PubMed

    Naddy, Rami B; Gorsuch, Joseph W; Rehner, Anita B; McNerney, Gina R; Bell, Russell A; Kramer, James R

    2007-08-15

    We investigated the chronic toxicity of Ag, as silver nitrate, using two freshwater aquatic cladoceran species, Ceriodaphnia dubia and Daphnia magna, to generate data for the development of a chronic ambient water quality criterion for Ag. Preliminary studies with C. dubia showed variable results which were related to the equilibration time between food and silver. Follow-up testing was conducted using a 3h equilibration time, which stabilized dissolved Ag concentrations and the toxicity of Ag(+). Results with C. dubia conducted individually (1 per cup, n=10) and in mass (30 per chamber, n=2) gave similar results once similar standardized equilibration times were used. The maximum acceptable toxicant concentration (MATC) of Ag to C. dubia and D. magna was 9.61 and 3.00microg dissolved Ag/L, respectively. The chronic toxicity of Ag(+) to C. dubia was also evaluated in the presence of: (1) dissolved organic carbon (DOC) and (2) sulfide. The addition of DOC (0.4mg/L) resulted in a approximately 50% decrease in toxicity while the addition of sulfide (75.4nM) deceased toxicity by 42%. Whole-body Ag concentration in D. magna was positively correlated with increased levels of Ag exposure, however; we observed a non-statistical decrease in whole-body Na levels, an estimator of sodium homeostasis.

  20. Chronic toxicity of chlordane to Daphnia magna and Ceriodaphnia dubia: a comparative study.

    PubMed

    Manar, Rachid; Vasseur, Paule; Bessi, Hlima

    2012-02-01

    Chronic toxicity of chlordane, an organochlorine insecticide, was assessed on Ceriodaphnia dubia under standardized conditions of testing. Results were compared to Daphnia magna to determine the sensitivity of the two freshwater cladoceran species to this persistent organic pollutant (POP) and to explore the possibility of using the 7-day C. dubia test as an alternative to the 21-day D. magna test in chronic toxicity assessment of POPs. The NOEC-7d value of chlordane on reproduction of C. dubia (2.9 μg/L) was much higher than the NOEC-21d value of D. magna (0.18 μg/L), attesting that the 7-day test on C. dubia was less sensitive than the 21-day reproduction test on D. magna to chlordane. However, extending the period of exposure of C. dubia to chlordane from 7 to 14 days led to a NOEC-14d value similar to the NOEC-21d value in D. magna (0.18 μg/L). This study highlights the usefulness of prolonging the exposure time of the reproduction test in C. dubia from 7 to 14 days to increase the performances of the reproduction test on C. dubia for assessing chronic toxicity of POPs.

  1. Biomonitoring of cyanotoxins in two tropical reservoirs by cladoceran toxicity bioassays.

    PubMed

    da S Ferrão-Filho, Aloysio; Soares, Maria Carolina S; de Freitas Magalhães, Valeria; Azevedo, Sandra M F O

    2009-02-01

    This study evaluates the potential for the use of cladocerans in biomonitoring of cyanobacterial toxins. Two zooplankton species (Daphnia gessneri and Moina micrura) were cultivated in the laboratory for use in acute (48 h) and chronic (10 days) bioassays. Water samples were collected from two reservoirs and diluted in mineral water at four concentrations. Survivorship in the acute bioassays was used to calculate LC50, and survivorship and fecundity in chronic bioassays were used to calculate the intrinsic population growth rate (r) and the EC50. Analysis of phytoplankton in the water samples from one reservoir revealed that cyanobacteria were the dominant group, represented by the genera Anabaena, Cylindrospermopsis, and Microcystis. Results of bioassays showed adverse effects including death, paralysis, and reduced population growth rate, generally proportional to the reservoir water concentration. These effects may be related to the presence of cyanobacteria toxins (microcystins or saxitoxins) in the water.

  2. Production of male neonates in four cladoceran species exposed to a juvenile hormone analog, fenoxycarb.

    PubMed

    Oda, Shigeto; Tatarazako, Norihisa; Watanabe, Hajime; Morita, Masatoshi; Iguchi, Taisen

    2005-06-01

    Previous studies have found that exposure of a cyclic parthenogen, the water flea Daphnia magna (Cladocera, Crustacea), to juvenile hormones and their analogs results in the production of neonates of male sex at concentration-dependent rates. We conducted reproduction experiments in four different species (Moina macrocopa, M. micrura, Ceriodaphnia dubia and C. reticulata) of cladoceran to test for the first time whether the occurrence of this phenomenon after exposure of the parent to such hormones is a generalized phenomenon. In the presence of a juvenile hormone analog, fenoxycarb, all four species produced male neonates and showed reduced rates of reproduction. The estimated median effective concentration (EC50) for the production of male neonates varied with species, ranging from 0.60 x 10(3) to 9.3 x 10(3) ng/l. Although there was a wide range of sensitivity to fenoxycarb, the production of male neonates in all four species demonstrates that this phenomenon is a common response to juvenile hormone analogs and further suggests that these hormones are capable of initiating sexual reproduction in cladocerans, most of which exhibit cyclic parthenogenesis.

  3. Effects of aqueous stable fullerene nanocrystals (nC60) on the food conversion from Daphnia magna to Danio rerio in a simplified freshwater food chain.

    PubMed

    Tao, Xianji; Li, Cuilan; Zhang, Bo; He, Yiliang

    2016-02-01

    Understanding the nanomaterial potential to the food conversion of two food chain levels is important in the ecosystem assessment as manufactured nanomaterials are being released into the environment. In this investigation, the food conversion from Daphnia magna (D. magna) (prey) to Danio rerio (D. rerio) (predator) was used as the study object of aqueous stable fullerene nanocrystals (nC60). Accumulated nC60 of D. magna was determined as the nominal initial exposure concentration for D. rerio. The results of 21-d dietary exposure experiment demonstrate that nC60 in D. magna decreased the body weight growths and condition factors of D. rerio, and reduced the food conversion ratio by 20% (from D. magna to D. rerio). Further, the experiments present that nC60 decrease three digestive enzymes activities of trypsinase, lipase, and amylase by 30, 29, and 55% in vivo, and by 60, 90, and 42% in vitro, respectively. Both in vivo and in vitro experiments indicated that nC60 was involved with the decrements of digestive enzymes activities. These decrements in digestive enzymes activities may be due to the deactivation caused by the adsorption of nC60 particles onto the surface or active center of digestive enzymes. Sum up, these results not only describe the nC60 deleterious effects on the food conversion from D. magna to D. rerio, but also provide some information regarding a probable food conversion inhibition mechanism of nC60.

  4. The protective roles of TiO2 nanoparticles against UV-B toxicity in Daphnia magna.

    PubMed

    Liu, Jie; Wang, Wen-Xiong

    2017-03-22

    Aquatic environments are increasingly under environmental stress due to ultraviolet (UV) radiation and potential inputs of nanoparticles with intense application of nanotechnology. In this study, we investigated the interaction between UV-B radiation and titanium nanoparticles (TiO2-NPs) in a model freshwater cladoceran Daphnia magna. UV-B toxicity to Daphnia magna was examined when the daphnids were exposed to a range of TiO2-NPs concentrations with an initial 5 or 10min of 200μW/cm(2) UV-B radiation. In addition, UV-B toxicity was also examined in the presence of TiO2-NPs in the body of daphnids. Our results demonstrated that the daphnid mortality under UV-B radiation decreased significantly in the presence of TiO2-NPs both in the water and in the body, indicating that TiO2-NPs had some protective effects on D. magna against UV-B. Such protective effect was mainly caused by the blockage of UV-B by TiO2-NPs adsorption. UV-B produced reactive oxygen species (ROS) in the water and in the daphnids, which was not sufficient to cause mortality of daphnids over short periods of radiation. Previous studies focused on the effects of TiO2-NPs on the toxicity of total UV radiation, and did not attempt to differentiate the potential diverse roles of UV-A and UV-B. Our study indicated that TiO2-NPs may conversely protect the UV-B toxicity to daphnids.

  5. Reprint of "Chronic toxicity of silver nitrate to Ceriodaphnia dubia and Daphnia magna, and potential mitigating factors".

    PubMed

    Naddy, Rami B; Gorsuch, Joseph W; Rehner, Anita B; McNerney, Gina R; Bell, Russell A; Kramer, James R

    2007-08-30

    We investigated the chronic toxicity of Ag, as silver nitrate, using two freshwater aquatic cladoceran species, Ceriodaphnia dubia and Daphnia magna, to generate data for the development of a chronic ambient water quality criterion for Ag. Preliminary studies with C. dubia showed variable results which were related to the equilibration time between food and silver. Follow-up testing was conducted using a 3 h equilibration time, which stabilized dissolved Ag concentrations and the toxicity of Ag(+). Results with C. dubia conducted individually (1 per cup, n=10) and in mass (30 per chamber, n=2) gave similar results once similar standardized equilibration times were used. The maximum acceptable toxicant concentration (MATC) of Ag to C. dubia and D. magna was 9.61 and 3.00 microg dissolved Ag/L, respectively. The chronic toxicity of Ag(+) to C. dubia was also evaluated in the presence of: (1) dissolved organic carbon (DOC) and (2) sulfide. The addition of DOC (0.4 mg/L) resulted in a approximately 50% decrease in toxicity while the addition of sulfide (75.4 nM) deceased toxicity by 42%. Whole-body Ag concentration in D. magna was positively correlated with increased levels of Ag exposure, however; we observed a non-statistical decrease in whole-body Na levels, an estimator of sodium homeostasis.

  6. First record of Daphnia lumholtzi Sars in the Great Lakes

    USGS Publications Warehouse

    Muzinic, Christopher J.

    2000-01-01

    Adults of the cladoceran Daphnia lumholtzi, native to Australia, Africa, and parts of Asia, were first collected in August 1999 in Lake Erie. Individuals were collected near East Harbor State Park, Lakeside, Ohio from vertical plankton net tows. The average number of D. lumholtzi that were found (0.03/L) indicate that D. lumholtzi is beginning to establish itself in Lake Erie. The morphology of this Daphnia differs greatly from native species because of its elongated head and tail spine. This sighting is important because it acknowledges yet another exotic invader into the Great Lakes basin and it also shows that this, normally, warm water species continues to expand its range northward.

  7. Environmental Effects of Dredging. Use of Daphnia Magna to Predict Consequences of Bioaccumulation.

    DTIC Science & Technology

    1987-03-01

    and biological effects in the freshwater crustacean, Daphnia magna (commonly known as the water flea). Procedures presented here for a 28-day Daphnia ... magna toxicity test could be used in screening for water-column toxicity resulting from open-water disposal of a specific dredged material. As a part

  8. Effect of ultraviolet light on toxicity of the PAH fluoranthene to freshwater organisms

    SciTech Connect

    Brooke, L.T.; Cox, D.; Kahl, M.; Spehar, R.L.

    1994-12-31

    Certain polyaromatic hydrocarbons (PAHs) can be activated by irradiation with ultraviolet light in the near UV waveband to increase their biocidal qualities. Fluoranthene is one of the PAHs that has this capacity. Ten species of freshwater animals and one species of freshwater plant were acutely exposed to several concentrations of fluoranthene in the presence of additional UV light and to standard light conditions. Tests were conducted using flow-through static or renewal techniques. Fluoranthene concentrations were measured using high pressure liquid chromatography. UV light was produced by UV-emitting fluorescent lamps. UV-C was removed from the spectrum by cellulose triacetate filters. Separate measurements were made of spectral ranges 310 to 390, 265 to 328 and < 320 nm. All species tested except for a dragonfly, Ophiogomphus sp. were more sensitive to fluoranthene in the presence of UV light ranging from 449 to 926 {mu}W/CM{sup 2} than the same species exposed to this chemical in tests using standard light conditions. Sensitivity increased by factors of {<=}32 times in these tests. Two species were tested for effects of UV light during chronic exposure. The cladoceran, Daphnia magna, showed a 17.1 fold increase in sensitivity to fluoranthene due to UV light and the fathead minnow showed a 5.77 fold increase. Results show that water quality criteria for fluoranthene should be adjusted for UV light effects.

  9. Bioassays on Illinois Waterway Dredged Material.

    DTIC Science & Technology

    1992-12-01

    48-hr) toxicity tests were conducted with two species, Pimephales promelas (the fathead minnow) and Daphnia magna (a freshwater cladoceran). A...chronic (21-day) toxicity test was also conducted using Daphnia magna . Animals were exposed separately to different concentrations of filtered and...unfiltered elutriates prepared from Acute, Cadmium, Daphnia magna , Pimephales promela, Ammonia, Chronic, Elutriate, Sediment, Bioassay, Cladoceran, Fathead

  10. Potassium enrichment stimulates the growth and reproduction of a clone of Daphnia dentifera.

    PubMed

    Civitello, David J; Hite, Jessica L; Hall, Spencer R

    2014-07-01

    Nutrient limitation commonly constrains organisms in natural ecosystems. Typically, ecologists focus on limitation by N and P. However, other nutrients can limit growth or reproduction. Here we focus on K limitation of invertebrate consumers (Daphnia dentifera) and phytoplankton in freshwater lakes. All organisms require K for several metabolic processes. In freshwater, K could limit growth because low external concentrations can increase the energetic costs of accumulating K. Furthermore, in a study linking K to disease, we previously found that K enrichment of water from one low-K lake stimulated the growth and reproduction of Daphnia. Here we test whether K could limit the production of Daphnia and phytoplankton across lakes and years. We repeated a life table experiment using water collected from a low-K lake during a different year. K again stimulated Daphnia reproduction. We also enriched water from 12 lakes with K or P and measured short-term growth of Daphnia and the resident algal community. Both nutrients increased Daphnia growth in five lakes. However, only P enhanced algal production. P stimulation of Daphnia positively correlated with algal quantity and the ratio of C to P in seston. However, K stimulation of Daphnia was not correlated with these factors or the background concentration of K. Thus, this study shows repeatable K-limited animal physiology in nature. Further, we can exclude the hypothesis that K stimulates Daphnia indirectly by enhancing algal production. These patterns call for future physiological studies to uncover the mechanistic basis of K limitation in natural systems.

  11. Effect of deltamethrin (pyrethroid insecticide) on two clones of Daphnia magna (Crustacea, Cladocera): a proteomic investigation.

    PubMed

    Toumi, Héla; Boumaiza, Moncef; Immel, Françoise; Sohm, Bénédicte; Felten, Vincent; Férard, Jean-François

    2014-03-01

    Deltamethrin is a class II pyrethroid insecticide commonly used in agriculture. It is hazardous to freshwater ecosystems, especially for the cladoceran Daphnia magna (Straus 1820). The results of our previous studies based on acute and chronic ecotoxicity experiments revealed differences in the sensitivity between two different clones. In this work, to investigate deltamethrin toxicity mechanisms in two clones of D. magna, we used a proteomic approach in order to analyze changes in protein expression profiles after 48 h of exposure. We detected 1339 spots; then applying statistical criteria (ANOVA p<0.001 and minimum fold change 1.5), only 128 spots were significantly different in the normalized volume. Among the preselected proteins there were 88 up-regulated and 40 down-regulated proteins. Results showed differences in sensitivities after deltamethrin exposure between the clones. Moreover, using the 2-DIGE method, proteomic investigation for deltamethrin exposure proved to be a reliable and powerful approach to investigate effects of deltamethrin as part of research for new metabolic and cellular biomarkers. After identification by mass spectrometry, there were 39 proteins recognized and identified, in which 21 and 18 were up- and down-regulated, respectively, in deltamethrin-exposed clone A compared to three other conditions (controls of each clone and deltamethrin-exposed clone 2). Up- and down-regulated proteins belonged to 12 biological processes (i.e. metabolic processes, apoptosis and stimulus response) and 5 molecular functions (i.e. catalytic activity, binding, structural molecular activity, antioxidant and receptor activities). Identification of these deregulated proteins opens a new way in discovering new molecular targets and putative biomarkers in daphnids exposed to deltamethrin.

  12. Rapid changes in water hardness and alkalinity: Calcite formation is lethal to Daphnia magna.

    PubMed

    Bogart, Sarah J; Woodman, Samuel; Steinkey, Dylan; Meays, Cindy; Pyle, Greg G

    2016-07-15

    There is growing concern that freshwater ecosystems may be negatively affected by ever-increasing anthropogenic inputs of extremely hard, highly alkaline effluent containing large quantities of Ca(2+), Mg(2+), CO3(2-), and HCO3(-) ions. In this study, the toxicity of rapid and extreme shifts in water hardness (38-600mg/L as CaCO3) and alkalinity (30-420mg/L as CaCO3) to Daphnia magna was tested, both independently and in combination. Within these ranges, where no precipitation event occurred, shifts in water hardness and/or alkalinity were not toxic to D. magna. In contrast, 98-100% of D. magna died within 96h after exposure to 600mg/L as CaCO3 water hardness and 420mg/L as CaCO3 alkalinity (LT50 of 60h with a 95% CI of 54.2-66.0h). In this treatment, a CaCO3 (calcite) precipitate formed in the water column which was ingested by and thoroughly coated the D. magna. Calcite collected from a mining impacted stream contained embedded organisms, suggesting field streams may also experience similar conditions and possibly increased mortality as observed in the lab tests. Although further investigation is required to determine the exact fate of aquatic organisms exposed to rapid calcite precipitation in the field, we caution that negative effects may occur more quickly or at lower concentrations of water hardness and alkalinity in which we observed effects in D. magna, because some species, such as aquatic insects, are more sensitive than cladocerans to changes in ionic strength. Our results provide evidence that both calcite precipitation and the major ion balance of waters should be managed in industrially affected ecosystems and we support the development of a hardness+alkalinity guideline for the protection of aquatic life.

  13. High bioconcentration of titanium dioxide nanoparticles in Daphnia magna determined by kinetic approach.

    PubMed

    Fan, Wenhong; Liu, Lingling; Peng, Ruishuang; Wang, Wen-Xiong

    2016-11-01

    The environmental risk assessments of titanium dioxide nanoparticles (TiO2 NPs) have drawn wide attention and one of the required critical information is the bioconcentration potentials of these nanoparticles in aquatic organisms. In the present study, the bioconcentration of six commercially available TiO2 NPs with different sizes and surface properties were quantified in a freshwater cladoceran Daphnia magna using kinetic modeling approach. We first calculated the uptake rate constant (ku) and depuration rate constant (ke) of TiO2 NPs and then employed a first-order kinetic model to predict the bioconcentration factors (BCF) at different TiO2 NPs concentrations. Both the ku and ke of TiO2 NPs were significantly affected by the exposure concentration and the nanoparticle property. The predicted BCF values in D. magna of six TiO2 NPs ranged from 2.40×10(5)L/kg to 1.52×10(6)L/kg, and had no clear correlation with the exposure concentration. Large nominal size resulted in a lower BCF of TiO2 NPs at lower exposure concentration. Higher hydrophobicity and Al(OH)3 coating also resulted in a higher BCF. All the six TiO2 NPs in this study were therefore considered very bioaccumulative. More attention should be paid to bioconcentration in the environmental risk assessments of TiO2 NPs, and the physicochemical properties of TiO2 NPs should be taken into account.

  14. First records of a European cladoceran, Bythotrephes cederstroemi, in Lakes Erie and Huron

    USGS Publications Warehouse

    Bur, Michael T.; Klarer, David M.; Krieger, Kenneth A.

    1986-01-01

    Adult forms of the cladoceran Bythotrephes cederstroemi Schoedler (Cercopagidae), a widespread European freshwater zooplankter, occurred in the stomachs of four common species of Lake Erie fish (yellow perch, Perca flavescens; white perch, Morone americana; white bass, M. chrysops; and walleye, Stizostedion vitreum vitreum) collected in early October 1985. The fish were collected at several stations in the nearshore open waters of the central basin between Ashtabula and Huron, Ohio. Other investigators have seen this species in other locations in Lake Erie and also in Lake Huron. The report of B. cederstroemi in Lake Huron in December 1984 appears to be the first record of this species in North America.

  15. Suitability of five cladoceran species from Mexico for in situ experimentation.

    PubMed

    Lopes, Isabel; Moreira-Santos, Matilde; Rendón-von Osten, Jaime; Baird, Donald J; Soares, Amadeu M V M; Ribeiro, Rui

    2011-01-01

    Although they are highly suited for site-specific risk assessment, little attention has been given to in situ ecotoxicological experimentation in tropical regions. This study intended to assess the suitability of five freshwater cladocerans from Mexico for in situ experiments. Juveniles of Ceriodaphnia cornuta, Macrothrix triserialis group, Simocephalus vetulus, Diaphanosoma birgei, and Pseudosida cf. ramosa, from two populations, were used to perform seven day laboratory and in situ experiments. Pseudosida cf. ramosa was very sensitive to handling and was discarded from further evaluations. Ceriodaphnia cornuta reproduced significantly more neonates, with smaller coefficients of variation, than M. triserialis and S. vetulus. Also due to its worldwide distribution in the tropics, C. cornuta is suggested to be highly suitable for in situ experiments.

  16. Microcystin accumulation in cladocerans: first evidence of MC uptake from aqueous extracts of a natural bloom sample.

    PubMed

    Ferrão-Filho, Aloysio S; Herrera, Natalia A; Echeverri, Luis Fernando

    2014-09-01

    Bioaccumulation of microcystins (MC) in zooplankton has been shown in several studies, mainly in field samples. A few studies, however, have demonstrated MC bioaccumulation in laboratory experiments. Although ingestion of cell-bound MC is considered the main route of MC accumulation, another important source is the MC from the dissolved fraction (DMC). This study reports the accumulation of DMC from aqueous extracts of natural bloom samples in three cladoceran species: Moina micrura, Daphnia laevis and Daphnia similis. Animals were exposed for 96 h to aqueous extracts of lyophilized matter from two bloom samples from Colombian reservoirs in different concentrations (25-1000 mg DW L(-1)). Analysis by HPLC-MS detected MC-LR in these samples at concentrations of 434-538 μg g(-1). For the analysis of MC in animal tissues the samples were homogenized and sonicated in methanol:water (75%) and analyzed by ELISA. Results showed that the animals uptake of MC increased with increasing exposure concentrations of aqueous extracts, with M. micrura and D. laevis clones presenting the highest MC concentrations in their tissues (up to 1170-1260 μg g(-1)) while D. similis the lowest (184 μg g(-1)). This study shows, for the first time, that MC uptake from dissolved fraction by zooplankton is possible, not only from the ingestion of seston or cell-bound MC as previously demonstrated.

  17. ULTRAVIOLET RADIATION AND ARSENIC INTERACTIONS: EFFECTS ON CLADOCERANS

    EPA Science Inventory

    The effects of arsenic and ultraviolet radiation (UV) on cladocerans have been examined separately, however the interaction of these two stresses has not been explored. Potential synergism between these two stresses is possible as arsenic is known to inhibit repair of UV induced ...

  18. Morphological changes in Daphnia galeata induced by a crustacean terpenoid hormone and its analog.

    PubMed

    Oda, Shigeto; Kato, Yasuhiko; Watanabe, Hajime; Tatarazako, Norihisa; Iguchi, Taisen

    2011-01-01

    Terpenoid hormones in insects (i.e., juvenile hormones) have various effects on physiology, morphology, and behavior, producing a wide range of phenotypic variation. Recent studies have shown that sex determination in cladoceran crustaceans is under the strong control of a major terpenoid hormone of crustaceans, methyl farnesoatote (MF). It can be easily conceived that MF is also a major determinant of other traits in cladocerans. In the present study, morphological changes known as antipredatory responses in a cladoceran Daphnia galeata in response to exposure to MF and a juvenile hormone-mimicking pesticide, fenoxycarb, were investigated. Morphological change was studied using neonates less than 24 h old, exposed either to MF at the concentrations from 1.9 to 30 µg/L, or fenoxycarb at the concentrations from 13 to 200 ng/L, for 6 d. Animals developed a longer helmet at 1.9 µg/L of MF and 25 ng/L of fenoxycarb, and showed a concentration-dependent elongation. However, the tail spine was reduced in size in a concentration-dependent manner. Results of the present study not only give new insight into the mechanisms of inducible defenses in cladocerans, but also provide invaluable information to understand ecological and evolutionary consequences of endocrine disruption through the shift in biological interaction between predator and prey.

  19. Acute toxicity of copper, ammonia, and chlorine to glochidia and juveniles of freshwater mussels (Unionidae)

    USGS Publications Warehouse

    Wang, N.; Ingersoll, C.G.; Hardesty, D.K.; Ivey, C.D.; Kunz, J.L.; May, T.W.; Dwyer, F.J.; Roberts, A.D.; Augspurger, T.; Kane, C.M.; Neves, R.J.; Barnhart, M.C.

    2007-01-01

    The objective of the present study was to determine acute toxicity of copper, ammonia, or chlorine to larval (glochidia) and juvenile mussels using the recently published American Society for Testing and Materials (ASTM) Standard guide for conducting laboratory toxicity tests with freshwater mussels. Toxicity tests were conducted with glochidia (24- to 48-h exposures) and juveniles (96-h exposures) of up to 11 mussel species in reconstituted ASTM hard water using copper, ammonia, or chlorine as a toxicant. Copper and ammonia tests also were conducted with five commonly tested species, including cladocerans (Daphnia magna and Ceriodaphnia dubia; 48-h exposures), amphipod (Hyalella azteca; 48-h exposures), rainbow trout (Oncorhynchus mykiss; 96-h exposures), and fathead minnow (Pimephales promelas; 96-h exposures). Median effective concentrations (EC50s) for commonly tested species were >58 ??g Cu/L (except 15 ??g Cu/L for C. dubia) and >13 mg total ammonia N/L, whereas the EC50s for mussels in most cases were 40 ??g/L and above the FAV in the WQC for chlorine. The results indicate that the early life stages of mussels generally were more sensitive to copper and ammonia than other organisms and that, including mussel toxicity data in a revision to the WQC, would lower the WQC for copper or ammonia. Furthermore, including additional mussel data in 2007 WQC for copper based on biotic ligand model would further lower the WQC. ?? 2007 SETAC.

  20. Revision of the Old World Daphnia (Ctenodaphnia) similis group Cladocera: Daphniidae).

    PubMed

    Popova, Ekaterina V; Petrusek, Adam; Kořínek, Vladimír; Mergeay, Joachim; Bekker, Eugeniya I; Karabanov, Dmitry P; Galimov, Yan R; Neretina, Tatyana V; Taylor, Derek J; Kotov, Alexey A

    2016-09-02

    Species of the genus Daphnia O.F. Müller, 1785 (Cladocera: Daphniidae) have become very important models in evolutionary biology research. Previous morphological and genetic evidence suggests that numerous closely related "species groups" exist within the subgenus Daphnia (Ctenodaphnia) Dybowski & Grochowski, 1895, containing both described and undescribed species. The Daphnia similis group is among these species groups. The aim of the present paper is to revise the taxonomy of the Daphnia (Ctenodaphnia) similis group in the Old World with both morphological and genetic evidence (based on mitochondrial COI and 12S rRNA genes). We found that there are at least four species in the Old World D. similis species group: D. similis Claus, 1876; D. sinensis Gu, Xu, Li, Dumont et Han, 2013; D. similoides Hudec, 1991 and D. inopinata sp. nov. These four taxa of the similis-group, confused previously with D. similis, have different distributional ranges in the Old World, from extremely wide, spanning several biogegraphic regions (as D. sinensis), to regional endemics (D. similoides) and even species known so far from a single locality (D. inopinata sp. nov.). The Daphnia similis group provides another example in the cladocerans whereby the study of males yields more valuable characters for taxonomy than the study of parthenogenetic females.

  1. Effect of vertebrate and invertebrate kairomones on the life history of Daphnia magna Straus (Crustacea: Branchiopoda).

    PubMed

    Chakri, Khemissa; Touati, Laïd; Alfarhan, Ahmed H; Al-Rasheid, Khaled A S; Samraoui, Boudjéma

    2010-01-01

    The history of selection of Daphnia magna populations living in North African temporary ponds may differ from populations inhabiting permanent ponds. Laboratory experiments were conducted to examine the effect of fish Gambusia holbrooki and invertebrate Notonecta glauca kairomones on the life history traits of the freshwater Cladocera Daphnia magna Straus. With fish kairomones, Daphnia reproduced early and had a significantly smaller size at first reproduction (SFR) and a smaller size of neonates compared to control. In contrast, daphnids reared in water treated with Notonecta glauca had no effect on the age at first reproduction but females were also smaller and produced smaller neonates.

  2. Calcium interacts with temperature to influence Daphnia movement rates

    PubMed Central

    Roszell, Jordan; Heyland, Andreas; Fryxell, John M.

    2016-01-01

    Predicting the ecological responses to climate change is particularly challenging, because organisms might be affected simultaneously by the synergistic effects of multiple environmental stressors. Global warming is often accompanied by declining calcium concentration in many freshwater ecosystems. Although there is growing evidence that these changes in water chemistry and thermal conditions can influence ecosystem dynamics, little information is currently available about how these synergistic environmental stressors could influence the behaviour of aquatic organisms. Here, we tested whether the combined effects of calcium and temperature affect movement parameters (average speed, mean turning frequency and mean-squared displacement) of the planktonic Daphnia magna, using a full factorial design and exposing Daphnia individuals to a range of realistic levels of temperature and calcium concentration. We found that movement increased with both temperature and calcium concentration, but temperature effects became considerably weaker when individuals were exposed to calcium levels close to survival limits documented for several Daphnia species, signalling a strong interaction effect. These results support the notion that changes in water chemistry might have as strong an effect as projected changes in temperature on movement rates of Daphnia, suggesting that even sublethal levels of calcium decline could have a considerable impact on the dynamics of freshwater ecosystems. PMID:28083097

  3. Impacts of zooplankton composition and algal enrichment on the accumulation of mercury in an experimental freshwater food web.

    PubMed

    Pickhardt, Paul C; Folt, Carol L; Chen, Celia Y; Klaue, Bjoern; Blum, Joel D

    2005-03-01

    There is a well documented accumulation of mercury in fish to concentrations of concern for human consumption. Variation in fish Hg burden between lakes is often high and may result from differences in Hg transfer through lower levels of the food web where mercury is bioconcentrated to phytoplankton and transferred to herbivorous zooplankton. Prior research derived patterns of mercury accumulation in freshwater invertebrates from field collected animals. This study provides results from controlled mesocosm experiments comparing the effects of zooplankton composition, algal abundance, and the chemical speciation of mercury on the ability of zooplankton to accumulate mercury from phytoplankton and transfer that mercury to planktivores. Experiments were conducted in 550-L mesocosms across a gradient of algal densities manipulated by inorganic nutrient additions. Enriched, stable isotopes of organic (CH3(200HgCl)) and inorganic (201HgCl2) mercury were added to mesocosms and their concentrations measured in water, seston, and three common zooplankton species. After 2 weeks, monomethylmercury (MMHg) concentrations were two to three times lower in the two copepod species, Leptodiaptomus minutus and Mesocyclops edax than in the cladoceran, Daphnia mendotae. All three zooplankton species had higher MMHg concentrations in mesocosms with low versus high initial algal abundance. However, despite higher concentrations of inorganic mercury (HgI) in seston from low nutrient mesocosms, there were no significant differences in the HgI accumulated by zooplankton across nutrient treatments. Bioaccumulation factors for MMHg in the plankton were similar to those calculated for plankton in natural lakes and a four-compartment (aqueous, seston, macrozooplankton, and periphyton/sediments) mass balance model after 21 days accounted for approximately 18% of the CH3(200Hg) and approximately 33% of the 201Hg added. Results from our experiments corroborate results from field studies and

  4. Relative sensitivity of one freshwater and two marine acute toxicity tests as determined by testing 30 offshore E & P chemicals.

    PubMed

    Sverdrup, Line E; Fürst, Charlotte S; Weideborg, Mona; Vik, Eilen A; Stenersen, Jørgen

    2002-01-01

    Acute toxicity of 30 offshore E & P (Exploration and Production) chemicals was measured using the three standard test organisms Daphnia magna (freshwater cladoceran), Acartia tonsa (marine copepod) and Skeletonema costatum (marine diatom alga). Test chemicals included 20 water-soluble and 10 (partially) non-soluble products. For 22 out of the 30 chemicals, the difference in sensitivity between the three tests varied within one order of magnitude. A very good correlation was found between the two marine tests (r = 0.96, P < 0.01, n = 30), and a correlation coefficient of r = 0.78 (P < 0.01, n = 30) was found between D. magna and both A. tonsa and S. costatum, individually. When the comparison of D. magna and A. tonsa sensitivity was based only on the water-soluble chemicals, a significantly higher correlation was obtained (r = 0.84, n = 20), indicating that the sample preparation method used for the (partially) non-soluble chemicals (the water accommodated fraction (WAF) method) induces additional variation between tests performed with different test media. (Partially) non-soluble chemicals are characterised by phase separation or precipitation at the concentrations used for testing. In a WAF-based test, each test concentration/exposure level is prepared separately, and following mixing and separation, only the water phase is used for testing. Toxicity is related to the amount of substance originally added to the mixing vessels. For 25 of the 30 chemicals, D. magna was found to be less sensitive than the marine copepod by a factor >2. The generally higher sensitivity of the marine toxicity tests compared to the Daphnia test emphasise the importance of using marine data for environmental hazard classification as well as for environmental risk assessment purposes.

  5. Increases of Chamber Height and Base Diameter Have Contrasting Effects on Grazing Rate of Two Cladoceran Species: Implications for Microcosm Studies

    PubMed Central

    Pan, Ying; Zhang, Yunshu; Peng, Yan; Zhao, Qinghua; Sun, Shucun

    2015-01-01

    Aquatic microcosm studies often increase either chamber height or base diameter (to increase water volume) to test spatial ecology theories such as “scale” effects on ecological processes, but it is unclear whether the increase of chamber height or base diameter have the same effect on the processes, i.e., whether the effect of the shape of three-dimensional spaces is significant. We orthogonally manipulated chamber height and base diameter and determined swimming activity, average swimming velocity and grazing rates of the cladocerans Daphnia magna and Moina micrura (on two algae Scenedesmus quadricauda and Chlorella vulgaris; leading to four aquatic algae-cladoceran systems in total) under different microcosm conditions. Across all the four aquatic systems, increasing chamber height at a given base diameter significantly decreased the duration and velocity of horizontal swimming, and it tended to increase the duration but decrease the velocity of vertical swimming. These collectively led to decreases in both average swimming velocity and grazing rate of the cladocerans in the tall chambers (at a given base diameter), in accordance with the positive relationship between average swimming velocity and grazing rate. In contrast, an increase of base diameter at a given chamber height showed contrasting effects on the above parameters. Consistently, at a given chamber volume increasing ratio of chamber height to base diameter decreased the average swimming velocity and grazing rate across all the aquatic systems. In general, increasing chamber depth and base diameter may exert contrasting effects on zooplankton behavior and thus phytoplankton-zooplankton interactions. We suggest that spatial shape plays an important role in determining ecological process and thus should be considered in a theoretical framework of spatial ecology and also the physical setting of aquatic microcosm experiments. PMID:26273836

  6. Changes in food (Chlorella) levels and the acute toxicity of cadmium to Daphnia carinata and Eschinisca triserialis

    SciTech Connect

    Chandini, T.

    1988-09-01

    Inasmuch as cadmium is known to be toxic to both fish and aquatic invertebrates due to bioaccumulation and biomagnification potential, the present study was initiated to determine the acute effects of cadmium on two cladoceran species - Daphnia carinata and Echinisca triserialis commonly found in fresh waters of Delhi. The two species in the extreme ends of the size continuum and were chosen to determine the magnitude of toxicity in relation to body size. As extraneous abiotic and biotic factors such as temperature, pH, food have been shown to greatly modify a pollutant stress, the present study was conducted with the objective of determining if differences in food levels could modify the acute toxicity effects of cadmium on these cladocerans. An attempt has also been made to compare these results with previous studies on cadmium toxicity.

  7. Toxicity of vanadium to different freshwater organisms

    SciTech Connect

    Beusen, J.M.; Neven, B.

    1987-08-01

    The aim of this study is to determine the acute and subchronic toxicity of vanadium for various species of freshwater fish. The long-term toxicity and the effect of vanadium on the reproduction of Daphnia magna is also evaluated and compared with the toxicity of other metals.

  8. Reverse osmosis sampling does not affect the protective effect of dissolved organic matter on copper and zinc toxicity to freshwater organisms.

    PubMed

    De Schamphelaere, K A C; Unamuno, V I R; Tack, F M G; Vanderdeelen, J; Janssen, C R

    2005-02-01

    Dissolved organic matter (DOM) plays a significant role in protecting freshwater organisms against metal toxicity. To study this, reverse osmosis (RO) has been widely used as a highly efficient method for rapid collection of large quantities of DOM from natural surface waters. The objective of this study was to examine the potential impact of the RO isolation technique on the protective effects of DOM on the toxicity of copper and zinc to the cladoceran Daphnia magna and the green alga Pseudokirchneriella subcapitata. DOM was concentrated from a natural surface water using RO and at the same time a natural (unconcentrated) surface water was taken. The concentrated DOM was rediluted to the level of the natural water to obtain the so-called reconstituted water. Chemical analyses and toxicity tests were performed with both the natural surface water and the reconstituted water. First, most chemical parameters were not significantly changed by the RO sampling. For both copper and zinc, no significant differences were observed in 48 h-EC50s for D. magna and in 72 h-EC50s for P. subcapitata between the reconstituted water and the natural water. Hence, it may be concluded that reverse osmosis does not significantly affect the protective effect of natural DOM against copper and zinc toxicity.

  9. Development and validation of a Daphnia magna four-day survival and growth test method

    EPA Science Inventory

    Zooplankton are an important part of the aquatic ecology of all lakes and streams. As a result, numerous methods have been developed to assess the quality of waterbodies using various zooplankton species. Included in these is the freshwater species Daphnia magna. Current test me...

  10. SALINITY TOLERANCE OF DAPHNIA MAGNA AND POTENTIAL USE FOR ESTUARINE SEDIMENT TOXICITY TESTS

    EPA Science Inventory

    Daphnia magna Straus, a common organism used for freshwater sediment toxicity tests, was evaluated to determine its tolerance to salinity and suitability for tests with estuarine water and sediments. Daphnids were exposed for 2 to 21 days to salinity in a variety of water-only te...

  11. Comparative acute freshwater hazard assessment and preliminary PNEC development for eight fluorinated acids.

    PubMed

    Hoke, Robert A; Bouchelle, Laurie D; Ferrell, Barbra D; Buck, Robert C

    2012-05-01

    Short-term 48, 72 and 96-h aquatic toxicity tests were conducted to evaluate the acute toxicity of eight fluorinated acids to the cladoceran, Daphnia magna, the green alga, Pseudokirchneriella subcapitata, and the rainbow trout, Oncorhynchus mykiss or the fathead minnow, Pimephales promelas. The eight fluorinated acids studied were tridecafluorohexyl ethanoic acid (6:2 FTCA), heptadecafluorooctyl ethanoic acid (8:2 FTCA), 2H-dodecafluoro-2-octenoic acid (6:2 FTUCA), 2H-hexadecafluoro-2-decenoic acid (8:2 FTUCA), 2H,2H,3H,3H-undecafluoro octanoic acid (5:3 acid), 2H,2H,3H,3H-pentadecafluoro decanoic acid (7:3 acid), n-perfluoropentanoic acid (PFPeA) and n-perfluorodecanoic acid (PFDA). The results of the acute toxicity tests conducted during this study suggest that the polyfluorinated acids, 8:2 FTCA, 8:2 FTUCA, 6:2 FTCA, 6:2 FTUCA, 7:3 acid and 5:3 acid, and the perfluorinated acids PFPeA and PFDA, are generally of low to medium concern based on evaluation of their acute freshwater toxicity (EC/LC50s typically between 1 and >100 mg L(-1)) using the USEPA TSCA aquatic toxicity evaluation paradigm. For the polyfluorinated acids, aquatic toxicity generally decreased as the number of fluorinated carbons decreased and as the overall carbon chain length decreased from 12 to 8. Acute aquatic toxicity of the 5 and 10 carbon perfluorocarboxylic acids (EC/LC50s between 10.6 and >100 mg L(-1)) was greater or similar to that of the 6-9 carbon perfluorocarboxylic acids (EC/LC50s>96.5 mg L(-1)). This study also provides the first report of the acute aquatic toxicity of the 5:3 acid (EC/LC50s of 22.5 to >103 mg L(-1)) which demonstrated less aquatic toxicity than the 7:3 acid (EC/LC50s of 0.4-32 mg L(-1)). The cladoceran, D. magna and the green alga, P. subcapitata had generally similar EC50 values for a given substance while fish were typically equally or less sensitive with the exception that PFPeA was most toxic to fish. Predicted no-effect concentrations (PNECs) were

  12. Effects of dietary copper on life-history traits of a tropical freshwater cladoceran.

    PubMed

    Gusso-Choueri, P K; Choueri, R B; Lombardi, A T; Melão, M G G

    2012-05-01

    Life-history parameters of Ceriodaphnia cornuta (Cladocera: Daphniidae) fed on Pseudokirchneriella subcapitata (Chlorophyceae) exposed to different copper concentrations were investigated. C. cornuta individuals were reared in four treatments: (a) reconstituted water and non-contaminated algae (RW); (b) reconstituted water and copper-contaminated algae with either 1.28 × 10(-13) (10(-7)Cu) or (c) 1.93 × 10(-13) g Cu cell(-1) (10(-6)Cu); and (d) natural water from a local reservoir and non-contaminated algae (NW). Copper content in C. cornuta individuals increased as diet-borne exposure increased (RW < 10(-7)Cu < NW < 10(-6)Cu), except for NW individuals, which exhibited higher copper body burden than RW and 10(-7)Cu individuals, suggesting that some copper was available in the natural water. The results suggest that subacute levels of dietary copper stimulated C. cornuta's growth and reproduction, whereas organisms reared on reconstituted water showed nutritional deficiency. Depending on copper exposure concentration, either growth (lower Cu concentration) or reproduction (higher Cu concentration) was further stimulated, suggesting that an alteration of resource allocation is involved in diet-borne copper exposure. Because differences among treatments were only significantly different after day 12 of the experiment, our results reinforce that full life-cycle tests are more appropriate than the standard 7 day or three-brood chronic bioassays used to evaluate dietary copper effects at low, chronic copper inputs and that the use of standard test-organisms may not address site-specific situations for tropical environments.

  13. Daphnia versus copepod impact on summer phytoplankton: functional compensation at both trophic levels.

    PubMed

    Sommer, Ulrich; Sommer, Frank; Santer, Barbara; Zöllner, Eckart; Jürgens, Klaus; Jamieson, Colleen; Boersma, Maarten; Gocke, Klaus

    2003-05-01

    Here we report on a mesocom study performed to compare the top-down impact of microphagous and macrophagous zooplankton on phytoplankton. We exposed a species-rich, summer phytoplankton assemblage from the mesotrophic Lake Schöhsee (Germany) to logarithmically scaled abundance gradients of the microphagous cladoceran Daphnia hyalinaxgaleata and of a macrophagous copepod assemblage. Total phytoplankton biomass, chlorophyll a and primary production showed only a weak or even insignificant response to zooplankton density in both gradients. In contrast to the weak responses of bulk parameters, both zooplankton groups exerted a strong and contrasting influence on the phytoplankton species composition. The copepods suppressed large phytoplankton, while nanoplanktonic algae increased with increasing copepod density. Daphnia suppressed small algae, while larger species compensated in terms of biomass for the losses. Autotrophic picoplankton declined with zooplankton density in both gradients. Gelatinous, colonial algae were fostered by both zooplankton functional groups, while medium-sized (ca. 3,000 microm3), non-gelatinous algae were suppressed by both. The impact of a functionally mixed zooplankton assemblage became evident when Daphnia began to invade and grow in copepod mesocosms after ca. 10 days. Contrary to the impact of a single functional group, the combined impact of both zooplankton groups led to a substantial decline in total phytoplankton biomass.

  14. Physiological interaction of Daphnia and Microcystis with regard to cyanobacterial secondary metabolites.

    PubMed

    Sadler, Thomas; von Elert, Eric

    2014-11-01

    Cyanobacterial blooms in freshwater ecosystems are a matter of high concern with respect to human health and ecosystem services. Investigations on the role of cyanobacterial secondary metabolites have largely been confined to microcystins, although cyanobacteria produce a huge variety of toxic or inhibitory secondary metabolites. Mass occurrences of toxic cyanobacteria strongly impact freshwater zooplankton communities; especially the unselective filter feeder Daphnia. Daphnids have been shown to successfully suppress bloom formation. However, the opposite situation, i.e. the suppression of Daphnia populations by cyanobacteria can be observed as well. To understand these contradictory findings the elucidation of the underlying physiological mechanisms that help daphnids to cope with cyanotoxins is crucial. We fed Daphnia magna with the cyanobacterium Microcystis aeruginosa PCC7806 for 24h and used high-resolution LCMS analytics to analyze the Microcystis cells, the Daphnia tissue and the surrounding medium in order to investigate the fate of seven investigated cyanobacterial compounds (cyanopeptolins A-C, microcyclamide 7806A and aerucyclamides B-D). For none of these bioactive compounds evidence for biotransformation or biodegradation by Daphnia were found. Instead feeding and subsequent release experiments point at the importance of transport mechanisms in Daphnia with regard to the cyanopeptolins A and C and microcyclamide 7806A. In addition we found hints for new inducible defense mechanism in Microcystis against predation by Daphnia. These putative defense mechanisms include the elevated production of toxic compounds other than microcystins, as could be demonstrated here for aerucyclamide B and D, cyanopoeptolin B and microcyclamide 7806A. Moreover, our data demonstrate the elevated active export of at least one cyanobacterial compound (microcyclamide 7806A) into the surrounding medium as a response to grazer presence, which might constitute an entirely new

  15. Chronic toxicity of chloride to freshwater species: effects of hardness and implications for water quality guidelines.

    PubMed

    Elphick, James R F; Bergh, Kelli D; Bailey, Howard C

    2011-01-01

    Toxicity tests using nine freshwater species (Ceriodaphnia dubia, Daphnia magna, Oncorhynchus mykiss, Pimephales promelas, Lumbriculus variegatus, Tubifex tubifex, Chironomus dilutus, Hyallela azteca, and Brachionus calyciflorus) were conducted to evaluate their sensitivity to chloride. Acute-to-chronic ratios (ACRs) from these tests indicate the ACR of 7.59 employed by the United States Environmental Protection Agency (U.S. EPA) in deriving its water quality guideline for chloride may be conservative; a revised ACR of 3.50 is presented here. The endpoints used to calculate the ACR included 24-h to 96-h median lethal concentrations (LC50s) for acute tests, and 48-h to 54-d inhibition concentration (ICx) values for growth or reproduction for chronic exposures. Data from the present chronic toxicity tests, and other investigators, were used to propose a water quality guideline for long-term exposure to chloride using a species sensitivity distribution (SSD) approach. The 5th percentile from the SSD was calculated as 307 mg/L and proposed as the water quality guideline. Cladocerans were the most sensitive species in the dataset. Ceriodaphnia dubia was used to evaluate the relationship between water hardness and sensitivity to chloride. A strong relationship was observed and was used to establish a hardness-related equation to modify the proposed water quality guideline on the basis of water hardness, resulting in values ranging from 64 mg/L chloride at 10 mg/L hardness to 388 mg/L chloride at 160 mg/L hardness (as CaCO₃). These data suggest that current water quality guidelines for chloride may be overly conservative in water with moderate-to-high hardness, and may not be sufficiently protective under soft-water conditions.

  16. TEMPORAL AND QUANTITATIVE CHANGES IN SEXUAL REPRODUCTIVE CYCLING OF THE CLADOCERAN DAPHNIA MAGNA BY A JUVENILE HORMONE ANALOG. (R826129)

    EPA Science Inventory

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  17. A comparison of the chronic effects of human pharmaceuticals on two cladocerans, Daphnia magna and Ceriodaphnia dubia.

    PubMed

    Constantine, L A; Huggett, D B

    2010-08-01

    Scientific researchers and regulators are focusing attention on trace quantities of pharmaceuticals in wastewater effluents and surface waters, resulting in an increased level of concern regarding the potential environmental impact of these compounds. The current European regulatory guideline requires evaluation of the chronic effects of active pharmaceutical ingredients on Daphniamagna. Based on the life cycle of D. magna, chronic studies to establish survival and reproductive endpoints require a 21 d exposure period. A similar organism, Ceriodaphniadubia, has a shorter life cycle and therefore survival and reproductive endpoints may be established following 7d of exposure. No observed effect concentrations and lowest observed effect concentrations for survival and reproduction were obtained for D. magna and C. dubia following exposure to six human pharmaceuticals and two metabolites (i.e. celecoxib, linezolid, varenicline, sunitinib, Compound A, ziprasidone and the M1 and M4 metabolites of torcetrapib). These data were evaluated to determine whether one organism may be considered more sensitive. Survival and reproduction data obtained from the C. dubia study provide similar outcomes to D. magna when determining the predicted environmental concentration/predicted no effect concentration (PEC/PNEC) ratios for surface water. Based on these data, C. dubia may be used as a cost-effective alternative and representative invertebrate species when assessing the potential risk of human pharmaceuticals.

  18. About the interest of a zooplankton compartment in pond systems: methodology to study the growth kinetic of Daphnia pulex on Scenedesmus sp.

    PubMed

    Liady, M N D; Tangou, T T; Fiogbe, E D; Cauchie, H-M; Vasel, J-L

    2015-01-01

    A reliable characterization of cladocerans' growth kinetic on their substrates is crucial for the estimation of their biochemical conversion rate in pond models. Although many studies reported cladocerans' growth inhibitions by high chlorophyceae contents, their growth kinetics had continued to be described in many pond system models by Monod-type kinetic, which describes growth saturation by high substrate contents, but fails to explain the disappearance of cladocerans observed during chlorophyceae's bloom periods. This study aimed to develop a methodology and assess whether growth-inhibition-type models used to describe microbial growth kinetics can be applicable to cladocerans. Experiments were carried out using Daphnia pulex populations and Scenedesmus sp. First, biomass of D. pulex was measured through digital image processing (DIP) during growth experiments. Then, three candidate models (i.e., Andrews, Edward and Haldane models), along with the Monod model, were fitted to the observed data and compared. The results showed that the DIP technique provided reliable results for estimating the biomass of D. pulex. Our findings show that the candidate growth inhibition-type models satisfactorily described D. pulex's growth kinetic (86% variance accounted for). Scenesdemus sp. were not strong inhibitors of the growth of D. pulex (high inhibition constant and low half-saturation constant found).

  19. Exposure to D2-like dopamine receptor agonists inhibits swimming in Daphnia magna.

    PubMed

    Barrozo, Enrico R; Fowler, David A; Beckman, Matthew L

    2015-10-01

    Daphnia are freshwater crustaceans that have been used for decades in ecotoxicology research. Despite the important role that Daphnia have played in environmental toxicology studies, very little is known about the neurobiology of Daphnia. Although many studies have investigated the swimming movements of these "water fleas", few studies have examined the underlying neurochemical basis for these movements. To characterize the locomotor effect of drugs in Daphnia, a two-dimensional video imaging tool was developed and animal tracking was performed with freely available software, CTRAX. Due to the central role that dopamine plays in the movement of animals, we sought to determine the role of dopamine receptor signaling in Daphnia movement by characterizing the effect of ten drugs that are agonists or antagonists of dopamine receptors. At 1, 2, and 6h of treatment with a 10μM drug, several dopamine receptor agonists with documented effects on the D2-like class of receptors decreased the movement. Further, we determined behavioral inhibition values (IC50) at 1h of treatment for (1R,3S)-1-(aminomethyl)-3-phenyl-3,4-dihydro-1H-isochromene-5,6-diol (A68930) to be 1.4μM and for bromocriptine to be 6.6μM. This study describes a new method to study Daphnia swimming and establishes this organism as a useful model for studies of dopaminergic signaling. Specifically, this study shows that a dopamine receptor signaling pathway, mediated by putative D2-like receptors, is involved in the control of Daphnia swimming behavior. Due to its ease of use and its rich motor program we propose that Daphnia should be considered for future studies of dopamine neuron toxicity and protection.

  20. Comparative Developmental Staging of Female and Male Water Fleas Daphnia pulex and Daphnia magna During Embryogenesis.

    PubMed

    Toyota, Kenji; Hiruta, Chizue; Ogino, Yukiko; Miyagawa, Shinichi; Okamura, Tetsuro; Onishi, Yuta; Tatarazako, Norihisa; Iguchi, Taisen

    2016-02-01

    The freshwater crustacean genus Daphnia has been used extensively in ecological, developmental and ecotoxicological studies. Daphnids produce only female offspring by parthenogenesis under favorable conditions, but in response to various unfavorable conditions and external stimuli, they produce male offspring. Although we reported that exogenous exposure to juvenile hormones and their analogs can induce male offspring even under female-producing conditions, we recently established a male induction system in the Daphnia pulex WTN6 strain simply by changing day-length. This male and female induction system is suitable for understanding the innate mechanisms of sexual dimorphic development in daphnids. Embryogenesis has been described as a normal plate (developmental staging) in various daphnid species; however, all studies have mainly focused on female development. Here, we describe the developmental staging of both sexes during embryogenesis in two representative daphnids, D. pulex and D. magna, based on microscopic time-course observations. Our findings provide the first detailed insights into male embryogenesis in both species, and contribute to the elucidation of the mechanisms underlying sexual differentiation in daphnids.

  1. Induction of male production in clones of Daphnia pulex by the juvenoid hormone methyl farnesoate under short photoperiod.

    PubMed

    Lampert, Winfried; Lampert, Kathrin P; Larsson, Petter

    2012-08-01

    The juvenile hormone, methyl farnesoate (MF), and its analog insecticides have been used successfully to induce the production of males in cladocerans under long-day conditions in the laboratory. However, without hormone addition Daphnia do not usually produce male offspring under long photoperiods, while short photoperiods are a stimulus for the induction of males. We used 21 clones of Daphnia pulex differing in their propensity to produce males under short-day conditions to test whether the treatment with MF would result in an additive effect of shifting the sex ratio towards males. Contrary to our expectations, clones with a high tendency of male production showed a reduced sex ratio in response to MF treatment under short-day conditions, but clones that produced normally few males or did not produce males were stimulated by 700 nM MF to produce up to 40% males. We suggest that the endocrine disruptive effect of MF or juvenile hormone analogs in the field may depend on the clonal composition of the cladoceran population and on the natural photoperiod. This may affect the seasonal occurrence of sexual reproduction and eventually cause a mismatch between the presence of males and ephippial females.

  2. Toxicity of cerium and thorium on Daphnia magna.

    PubMed

    Ma, Yuhui; Wang, Jingkun; Peng, Can; Ding, Yayun; He, Xiao; Zhang, Peng; Li, Na; Lan, Tu; Wang, Dongqi; Zhang, Zhaohui; Sun, Fuhong; Liao, Haiqing; Zhang, Zhiyong

    2016-12-01

    Cerium (Ce) and thorium (Th) are always thought to be chemically similar and have comparable toxic properties on living organisms. In the present study, the acute and chronic toxicity of these two elements to freshwater crustacean Daphnia magna were investigated in the modified reconstituted water (6mg/L KCl, 123mg/L MgSO4·7H2O, and 294mg/L CaCl2·2H2O in Milli-Q water, pH 7.8). It seemed that Ce and Th had comparable acute toxicity on Daphnia: 24/48h EC50 for Th and Ce were 7.3/4.7μM and 16.4/10.7μM, respectively. However, Ce was present as soluble ions while all of Th was present as particulate ThO2 in the exposure medium. Considering their different chemical forms and bioavailability, the toxic mechanisms of Ce(3+) and ThO2 on Daphnia would be totally different. To our knowledge, this is the first time to investigate the aquatic toxicity of thorium and cerium based on their actual chemical speciation in the exposure medium. The results also suggest that more attention should be paid on the detrimental effect of Th in the form of particulate ThO2.

  3. [Final thermal preference in parthenogenetic females of Daphnia magna Straus (Crustacea: Cladocera) acclimated to various temperatures].

    PubMed

    Verbitskiĭ, V B; Verbitskaia, T I

    2011-01-01

    The final thermal preference (FTP) range in parthenogenetic females of cladoceran Daphnia magna was assessed by "acute" and "chronic" methods. The first method included 4-month acclimation to different temperatures in the range of 14.2 +/- 0.7 to 27.1 +/- 0.3 degrees C; the "chronic" method was characterized by long-term acclimation to +20 degrees C. Two ranges of FTP were found for D. magna, 13.3-15.4 degrees C and 20.2-26.2 degrees C. The thermal preference ofdaphnids and the temperature of acclimation were correspondingly linearly. The range of FTP was independent of the season. The food-searching activity of D. magna rose in April, when the FTP range increased, and the FTP was less pronounced.

  4. The ecoresponsive genome of Daphnia pulex

    SciTech Connect

    Colbourne, John K.; Pfrender, Michael E.; Gilbert, Donald; Thomas, W. Kelley; Tucker, Abraham; Oakley, Todd H.; Tokishita, Shinichi; Aerts, Andrea; Arnold, Georg J.; Basu, Malay Kumar; Bauer, Darren J.; Caceres, Carla E.; Carmel, Liran; Casola, Claudio; Choi, Jeong-Hyeon; Detter, John C.; Dong, Qunfeng; Dusheyko, Serge; Eads, Brian D.; Frohlich, Thomas; Geiler-Samerotte, Kerry A.; Gerlach, Daniel; Hatcher, Phil; Jogdeo, Sanjuro; Krijgsveld, Jeroen; Kriventseva, Evgenia V; Kültz, Dietmar; Laforsch, Christian; Lindquist, Erika; Lopez, Jacqueline; Manak, Robert; Muller, Jean; Pangilinan, Jasmyn; Patwardhan, Rupali P.; Pitluck, Samuel; Pritham, Ellen J.; Rechtsteiner, Andreas; Rho, Mina; Rogozin, Igor B.; Sakarya, Onur; Salamov, Asaf; Schaack, Sarah; Shapiro, Harris; Shiga, Yasuhiro; Skalitzky, Courtney; Smith, Zachary; Souvorov, Alexander; Sung, Way; Tang, Zuojian; Tsuchiya, Dai; Tu, Hank; Vos, Harmjan; Wang, Mei; Wolf, Yuri I.; Yamagata, Hideo; Yamada, Takuji; Ye, Yuzhen; Shaw, Joseph R.; Andrews, Justen; Crease, Teresa J.; Tang, Haixu; Lucas, Susan M.; Robertson, Hugh M.; Bork, Peer; Koonin, Eugene V.; Zdobnov, Evgeny M.; Grigoriev, Igor V.; Lynch, Michael; Boore, Jeffrey L.

    2011-02-04

    This document provides supporting material related to the sequencing of the ecoresponsive genome of Daphnia pulex. This material includes information on materials and methods and supporting text, as well as supplemental figures, tables, and references. The coverage of materials and methods addresses genome sequence, assembly, and mapping to chromosomes, gene inventory, attributes of a compact genome, the origin and preservation of Daphnia pulex genes, implications of Daphnia's genome structure, evolutionary diversification of duplicated genes, functional significance of expanded gene families, and ecoresponsive genes. Supporting text covers chromosome studies, gene homology among Daphnia genomes, micro-RNA and transposable elements and the 46 Daphnia pulex opsins. 36 figures, 50 tables, 183 references.

  5. Translocation of 40 nm diameter nanowires through the intestinal epithelium of Daphnia magna.

    PubMed

    Mattsson, Karin; Adolfsson, Karl; Ekvall, Mikael T; Borgström, Magnus T; Linse, Sara; Hansson, Lars-Anders; Cedervall, Tommy; Prinz, Christelle N

    2016-10-01

    Nanowires (NWs) have unique electrical and optical properties of value for many applications including lighting, sensing, and energy harnessing. Consumer products containing NWs increase the risk of NWs being released in the environment, especially into aquatic ecosystems through sewage systems. Daphnia magna is a common, cosmopolitan freshwater organism sensitive to toxicity tests and represents a likely entry point for nanoparticles into food webs of aquatic ecosystems. Here we have evaluated the effect of NW diameter on the gut penetrance of NWs in Daphnia magna. The animals were exposed to NWs of two diameters (40 and 80 nm) and similar length (3.6 and 3.8 μm, respectively) suspended in water. In order to locate the NWs in Daphnia, the NWs were designed to comprise one inherently fluorescent segment of gallium indium phosphide (GaInP) flanked by a gallium phosphide (GaP) segment. Daphnia mortality was assessed directly after 24 h of exposure and 7 days after exposure. Translocation of NWs across the intestinal epithelium was investigated using confocal fluorescence microscopy directly after 24 h of exposure and was observed in 89% of Daphnia exposed to 40 nm NWs and in 11% of Daphnia exposed to 80 nm NWs. A high degree of fragmentation was observed for NWs of both diameters after ingestion by the Daphnia, although 40 nm NWs were fragmented to a greater extent, which could possibly facilitate translocation across the intestinal epithelium. Our results show that the feeding behavior of animals may enhance the ability of NWs to penetrate biological barriers and that penetrance is governed by the NW diameter.

  6. Translocation of 40 nm diameter nanowires through the intestinal epithelium of Daphnia magna

    PubMed Central

    Mattsson, Karin; Adolfsson, Karl; Ekvall, Mikael T.; Borgström, Magnus T.; Linse, Sara; Hansson, Lars-Anders; Cedervall, Tommy; Prinz, Christelle N.

    2016-01-01

    Abstract Nanowires (NWs) have unique electrical and optical properties of value for many applications including lighting, sensing, and energy harnessing. Consumer products containing NWs increase the risk of NWs being released in the environment, especially into aquatic ecosystems through sewage systems. Daphnia magna is a common, cosmopolitan freshwater organism sensitive to toxicity tests and represents a likely entry point for nanoparticles into food webs of aquatic ecosystems. Here we have evaluated the effect of NW diameter on the gut penetrance of NWs in Daphnia magna. The animals were exposed to NWs of two diameters (40 and 80 nm) and similar length (3.6 and 3.8 μm, respectively) suspended in water. In order to locate the NWs in Daphnia, the NWs were designed to comprise one inherently fluorescent segment of gallium indium phosphide (GaInP) flanked by a gallium phosphide (GaP) segment. Daphnia mortality was assessed directly after 24 h of exposure and 7 days after exposure. Translocation of NWs across the intestinal epithelium was investigated using confocal fluorescence microscopy directly after 24 h of exposure and was observed in 89% of Daphnia exposed to 40 nm NWs and in 11% of Daphnia exposed to 80 nm NWs. A high degree of fragmentation was observed for NWs of both diameters after ingestion by the Daphnia, although 40 nm NWs were fragmented to a greater extent, which could possibly facilitate translocation across the intestinal epithelium. Our results show that the feeding behavior of animals may enhance the ability of NWs to penetrate biological barriers and that penetrance is governed by the NW diameter. PMID:27181920

  7. How does the Taquari River influence in the cladoceran assemblages in three oxbow lakes?

    PubMed

    Panarelli, E A; Güntzel, A M; Borges, C N

    2013-11-01

    This study examined the cladoceran assemblages in three oxbow lakes of the Taquari River floodplain, near the transition between the plateau and the plain. We sought to answer the following questions: does the Taquari River function as a geographical barrier or dispersal corridor for Cladocera? Can different degrees of connection induce different structures in the assemblages in each lake? Cladocerans and limnological variables were sampled every other month for one year. Forty-one species were recorded, four of which were common to all the lakes. Our results indicated that the different degrees of connection between the river and the oxbow lakes favoured environmental heterogeneity and diversification in the cladoceran assemblages. The greatest dissimilarity between the two lakes connected with the river indicates that in this case the river functions better as a barrier than a dispersal corridor.

  8. Small RNA Sequencing Based Identification of MiRNAs in Daphnia magna.

    PubMed

    Ünlü, Ercan Selçuk; Gordon, Donna M; Telli, Murat

    2015-01-01

    Small RNA molecules are short, non-coding RNAs identified for their crucial role in post-transcriptional regulation. A well-studied example includes miRNAs (microRNAs) which have been identified in several model organisms including the freshwater flea and planktonic crustacean Daphnia. A model for epigenetic-based studies with an available genome database, the identification of miRNAs and their potential role in regulating Daphnia gene expression has only recently garnered interest. Computational-based work using Daphnia pulex, has indicated the existence of 45 miRNAs, 14 of which have been experimentally verified. To extend this study, we took a sequencing approach towards identifying miRNAs present in a small RNA library isolated from Daphnia magna. Using Perl codes designed for comparative genomic analysis, 815,699 reads were obtained from 4 million raw reads and run against a database file of known miRNA sequences. Using this approach, we have identified 205 putative mature miRNA sequences belonging to 188 distinct miRNA families. Data from this study provides critical information necessary to begin an investigation into a role for these transcripts in the epigenetic regulation of Daphnia magna.

  9. Chronic toxicity of hydrogen peroxide to Daphnia magna in a continuous exposure, flow-through test system

    USGS Publications Warehouse

    Meinertz, J.R.; Greseth, Shari L.; Gaikowski, M.P.; Schmidt, L.J.

    2008-01-01

    A flow-through, continuous exposure test system was developed to expose Daphnia magna to an unstable compound. 35% Perox-Aid?? is a specially formulated hydrogen peroxide (a highly oxidative chemical) product approved for use in U.S. aquaculture and therefore has the potential to be released from aquaculture facilities and pose a risk to aquatic invertebrates. The study objective was to assess the effects of 35% Perox-Aid?? on an aquatic invertebrate by evaluating the survival, growth, production, and gender ratio of progeny from a representative aquatic invertebrate continuously exposed to 35% Perox-Aid??. The study design consisted of 6 treatment groups (10 test chambers each) with target hydrogen peroxide concentrations of 0.0, 0.32, 0.63, 1.25, 2.5, and 5.0??mg L- 1. The study was initiated with < 24-h-old Daphnia (1 daphnid per chamber) that were exposed to hydrogen peroxide for 21??days. Hydrogen peroxide concentrations ??? 1.25??mg L- 1 had no significant effect on Daphnia time to death compared to controls and no significant effect on the time to first brood production and the number of broods produced. Concentrations ??? 0.63??mg L- 1 had no significant effect on the total number of young produced. Concentrations ??? 0.32??mg L- 1 had a negative effect on Daphnia growth. Hydrogen peroxide had no significant effect on the gender ratio of young produced. All second generation Daphnia were female. A continuous discharge of hydrogen peroxide into aquatic ecosystems is not likely to affect cladocerans if the concentration is maintained at ??? 0.63??mg L- 1 for less than 21??days.

  10. Role of B-esterases in assessing toxicity of organophosphorus (chlorpyrifos, malathion) and carbamate (carbofuran) pesticides to Daphnia magna.

    PubMed

    Barata, Carlos; Solayan, Arun; Porte, Cinta

    2004-02-10

    In this study, the cladoceran Daphnia magna was exposed to two model organophosphorous and one carbamate pesticides including malathion, chlorpyrifos and carbofuran to assess acetylcholinesterase (AChE) and carboxylesterase (CbE) inhibition and recovery patterns and relate those responses with individual level effects. Our results revealed differences in enzyme inhibition and recovery patterns among the studied esterase enzymes and pesticides. CbE was more sensitive to organophosphorous than AChE, whereas both CbE and AChE showed equivalent sensitivities to the carbamate carbofuran. Recovery patterns of AChE and CbE activities following exposure to the studied pesticides were similar with 80-100% recoveries taking place 12 and 96 h after exposure to organophosphorous and carbamates pesticides, respectively. The physiological role of AChE and CbE inhibition patterns in Daphnia was examined by using organophosphorous and carbamate compounds alone and with specific inhibitors of CbE. Under exposure to organophosphorous pesticides, survival of Daphnia juveniles was impaired at AChE inhibition levels higher than 50% whereas under exposure to the carbamate carbofuran low levels of AChE inhibition affected mortality. Inhibition of CbE by 80-90% increased toxicity to organophosphorous and carbamate pesticides by up to two- and four-fold, respectively. Our results suggest that both AChE and CbE enzymes are involved in determining toxicity of Daphnia to the studied chemicals and that AChE inhibition levels higher than 50% can be considered of environmental concern to Daphnia species.

  11. Comparative analysis between native and reference cladocerans to assess the toxic effects of products used by the oil industry in Mexico.

    PubMed

    Muñoz-Mejía, Guillermo; Zavala-Olivares, Gerardo; Martínez-Jerónimo, Fernando

    2007-08-01

    In this study, native cladocerans, Scapholeberis armata freyi and Macrothrix elegans, were collected from the region and their offspring were used as test organisms to assess the effects of 18 corrosion and scale inhibitors, widely used to protect oil pipelines. Daphnia magna and Ceriodaphnia dubia were used as international reference species, and their sensitivity was compared to native species and assessed with the reference toxicant Cr(VI). We also determined the correlation between the native and the reference species. Corrosion inhibitors were grouped according to their uses and acute toxicity gradient; those used for multifunction pipelines are considered moderately toxic (LC(50) of 10 to 100 mg/L), and the remainder as toxic (LC(50) between 1.0 and 10 mg/L). Scale inhibitors are considered non-toxic, since the LC(50) for the 4 species exceeded 2,000 mg/L. Sensitivity test to Cr(VI) indicated that M. elegans was the least sensitive species. There was a high correlation (> 90%) in sensitivity among M. elegans, D. magna, and C. dubia to the corrosion inhibitors used. Hence, it is feasible to use these native species from Southeast Mexico as substitutes of the typical reference species.

  12. Freshwater Macroinvertebrates.

    ERIC Educational Resources Information Center

    Nalepa, T. F.

    1978-01-01

    Presents a literature review of freshwater biology particularly freshwater macroinvertebrates and their effect on water pollution, covering publications of 1976-77. A list of 158 references is also presented. (HM)

  13. Linking genes to communities and ecosystems: Daphnia as an ecogenomic model.

    PubMed

    Miner, Brooks E; De Meester, Luc; Pfrender, Michael E; Lampert, Winfried; Hairston, Nelson G

    2012-05-22

    How do genetic variation and evolutionary change in critical species affect the composition and functioning of populations, communities and ecosystems? Illuminating the links in the causal chain from genes up to ecosystems is a particularly exciting prospect now that the feedbacks between ecological and evolutionary changes are known to be bidirectional. Yet to fully explore phenomena that span multiple levels of the biological hierarchy requires model organisms and systems that feature a comprehensive triad of strong ecological interactions in nature, experimental tractability in diverse contexts and accessibility to modern genomic tools. The water flea Daphnia satisfies these criteria, and genomic approaches capitalizing on the pivotal role Daphnia plays in the functioning of pelagic freshwater food webs will enable investigations of eco-evolutionary dynamics in unprecedented detail. Because its ecology is profoundly influenced by both genetic polymorphism and phenotypic plasticity, Daphnia represents a model system with tremendous potential for developing a mechanistic understanding of the relationship between traits at the genetic, organismal and population levels, and consequences for community and ecosystem dynamics. Here, we highlight the combination of traits and ecological interactions that make Daphnia a definitive model system, focusing on the additional power and capabilities enabled by recent molecular and genomic advances.

  14. Toxicity of various silver nanoparticles compared to silver ions in Daphnia magna

    PubMed Central

    2012-01-01

    Background To better understand the potential ecotoxicological impacts of silver nanoparticles released into freshwater environments, the Daphnia magna 48-hour immobilization test was used. Methods The toxicities of silver nitrate, two types of colloidal silver nanoparticles, and a suspension of silver nanoparticles were assessed and compared using standard OECD guidelines. Also, the swimming behavior and visible uptake of the nanoparticles by Daphnia were investigated and compared. The particle suspension and colloids used in the toxicity tests were well-characterized. Results The results obtained from the exposure studies showed that the toxicity of all the silver species tested was dose and composition dependent. Plus, the silver nanoparticle powders subsequently suspended in the exposure water were much less toxic than the previously prepared silver nanoparticle colloids, whereas the colloidal silver nanoparticles and AgNO3 were almost similar in terms of mortality. The silver nanoparticles were ingested by the Daphnia and accumulated under the carapace, on the external body surface, and connected to the appendages. All the silver species in this study caused abnormal swimming by the D. magna. Conclusion According to the present results, silver nanoparticles should be classified according to GHS (Globally Harmonized System of classification and labeling of chemicals) as "category acute 1" to Daphnia neonates, suggesting that the release of nanosilver into the environment should be carefully considered. PMID:22472056

  15. Population responses of Daphnia magna, Chydorus sphaericus and Asellus aquaticus in pesticide contaminated ditches around bulb fields.

    PubMed

    Ieromina, O; Peijnenburg, W J G M; de Snoo, G R; Vijver, M G

    2014-09-01

    The goal of this study was to investigate the effects of ambient concentrations of pesticides combined with abiotic factors on the key aquatic species Daphnia magna, Chydorus sphaericus and Asellus aquaticus by means of 21 days field exposure experiments. In situ bioassays were deployed in ditches around flower bulb fields during spring and autumn 2011-2012. The results showed that phosphate was the most variable parameter followed by pesticides expressed as toxic units, as the main factors explaining differences between sites. Variation in reproduction and growth of cladoceran D. magna was largely explained by nutrients, whereas dissolved oxygen contributed mostly to variations in reproduction of C. sphaericus. Dissolved organic carbon contributed to variations in growth of the detrivore A. aquaticus. It is concluded that abiotic stressors rather than pesticides contributed significantly to the performance of aquatic invertebrates.

  16. Effects of chemical stress on the population dynamics of Daphnia magna: a comparison of two test procedures

    SciTech Connect

    van Leeuwen, C.J.; Niebeek, G.; Rijkeboer, M.

    1987-08-01

    Ten substances were tested to compare two methods that can be used in chronic toxicity studies with the Cladoceran Daphnia magna. In semistatic experiments with cohorts (life-table studies) survival appeared to be a dominant factor in exponential population growth. Specific inhibition of reproduction as a result of toxic stress was observed only in tests with bromide and 2,4-dichloroaniline. For some substances (cadmium, bichromate, metavanadate, and bromide) individual growth (carapace length) was found to be a sensitive parameter. In intermittent-flow experiments with small expanding populations the yield (carrying capacity) proved to be a highly sensitive parameter, probably owing to the fact that in these tests populations grow logistically, i.e., become additionally stressed by food limitation. Chemically induced reductions in food ingestion and conversion efficiency may thus become very predominant. In view of the place of these crustaceans in the food web such reductions in the carrying capacity would seem to be of great ecotoxicological importance.

  17. Reproductive aspects of marine cladocerans Penilia avirostris and Pseudevadne tergestina (Crustacea, Branchiopoda) in the outer part of Guanabara Bay, Brazil.

    PubMed

    Marazzo, A; Valentin, J L

    2004-08-01

    The objective of this study was to report on some aspects of marine cladoceran reproduction in Guanabara Bay. Samples were collected during 1985 using a conical net with 200 microm mesh. Two species were identified: Penilia avirostris and Pseudevadne tergestina. Both species disappeared from the plankton in winter. Two months before this phenomenon, parthenogenetic females displayed reduction in brood size, while gamogenetic individuals appeared among the populations. This sequence of events is generally typical of marine cladoceran populations in temperate waters.

  18. Environmental effects of dredging. Use of daphnia magna to predict consequences of bioaccumulation

    SciTech Connect

    1987-03-01

    Results reported herein represent a portion of the laboratory research evaluating the relationship between mercury and cadmium tissue residues and biological effects in the freshwater crustacean, Daphnia magna (commonly known as the water flea). Procedures presented here for a 28-day Daphnia magna toxicity test could be used in screening for water-column toxicity resulting from open-water disposal of a specific dredged material. As a part of its regulatory and dredging programs, the U. S. Army Corps of Engineers often conducts, or requires to be conducted, an assessment of the potential for bioaccumulation of environmental contaminants from sediment scheduled for dredging and open-water disposal. There is, at present, no generally accepted guidance available to aid in the interpretation of the biological consequences of bioaccumulation. To provide an initial basis for such guidance, the Environmental Laboratory is conducting both literature database analyses and experimental laboratory studies as part of the Long-Term Effects of Dredging Operations (LEDO) Program.

  19. Adsorption, uptake and distribution of gold nanoparticles in Daphnia magna following long term exposure.

    PubMed

    Botha, Tarryn Lee; Boodhia, Kailen; Wepener, Victor

    2016-01-01

    Gold nanoparticles (nAu) have recently been studied and developed within the biological and photothermal therapeutic contexts. The major clinical interest is within the application of novel drug delivery systems. Environmental exposure to nanoparticles can occur in different stages of the lifecycle of the product; from their synthesis, applications, product weathering and their disposal. Freshwater Daphnids, specifically Daphnia magna, have been used since the 1960s as a standard species in acute and chronic aquatic toxicity testing. Visualization of the interactions and uptake of nAu by D. magna was related to reproduction and molting patterns. Exposure to nAu was done using a chronic reproduction test performed for 14 days at six concentrations (0.5mg/L, 2mg/L, 5mg/L, 10mg/L, 15mg/L and 20mg/L). Microscopy was used to determine whether there was any uptake or interaction of nAu with daphnia. However the concentration of nAu in the media and the charge of particles played a role in the uptake and surface adsorption. As exposure concentrations of nAu increased it appeared that the nAu aggregated onto the surface and in the gut of the organisms in higher concentrations. There was no evidence of nAu internalization into the body cavity of the daphnia. Aquatic exposure to nAu resulted in increased adhesion of the particles to the carapace of daphnia, ingestion and uptake into the gut of daphnia and had no significant effect on reproduction and molting patterns.

  20. Comparative toxicity of selenate, selenite, seleno-DL-methionine and seleno-DL-cystine to Daphnia magna

    SciTech Connect

    Maier, K.J.; Foe, C.G.; Knight, A.W. )

    1993-04-01

    Elevated concentrations of the trace element selenium (Se) have resulted in the degradation of several aquatic ecosystems. This study evaluated the comparative toxicity of several aqueous chemical species of selenium to an aquatic cladoceran, Daphnia magna. Responses to mixtures of these selenium forms, varying the sulfate concentration, were also examined. Initial experiments compared the toxicity of aqueous forms of selenate, selenite, seleno-DL-methionine, and seleno-DL-cystine to neonate Daphnia magna, resulting in 4-h LC50 values of 2.84, 0.55, 0.31, and 2.01 mg Se per liter, respectively. Immobilization was an acute sublethal response observed during exposure to the organic selenium forms only. The 48-h IC50 values were 0.045 and 0.52 mg Se per liter for seleno-DL-methionine and seleno-DL-cystine, respectively. Evaluation of the invertebrate response to various combinations of selenate, selenite, and seleno-DL-methionine demonstrated that the toxicities of these forms of selenium are additive. Increasing the concentration of sulfate decreased, varied, and left unaffected the toxicities of selenate, selenite, and seleno-DL-methionine, respectively. These results indicate that both the chemical form of selenium and the sulfate concentration can influence the toxicity of selenium.

  1. Effects of inorganic turbidity and reservoir floods on the feeding and population dynamics of Cladoceran zooplankton

    SciTech Connect

    Shuman, J.R.

    1988-01-01

    Clearance rates of {sup 32}P-labeled yeast cell tracer particles and gravimetric seston analysis were used to estimate in situ seston ingestion rates of Daphnia parvula and Bosmina along the seston gradient in Tuttle Creek Reservoir, near Manhattan, Kansas. An ingestion rate depression occurred for both species at the highest seston concentration. The smallest animals, Bosmina, had a lower incipient limiting concentration and exhibited a stronger ingestion rate depression. The fecundity and abundance of Daphnia parvula, grown in enclosures along the seston gradient prior to the ingestion rate measurements, were highest at the river inflow region. Reservoir Bosmina, however, were least abundant and had the lowest fecundity at the river inflow region. The abundance of Bosmina, calanoid copepods, and cyclopoid copepods were lower following large storm inflows in the late spring of 1983 and 1984, while the abundance of Diaphanosoma and Moina were similar. Both open reservoir and in situ enclosure populations of Daphnia pulex were reduced following the storm inflow, while only enclosure populations of Daphnia parvula were lower. Diaphanosoma and calanoid copepods dominated the zooplankton during sampling from spring through fall 1984, particularly in midsummer when temperatures were greater than 25{degree}C. Daphnids dominated numerically during the fall baseflow period.

  2. Annotation of the Daphnia magna nuclear receptors: comparison to Daphnia pulex.

    PubMed

    Litoff, Elizabeth J; Garriott, Travis E; Ginjupalli, Gautam K; Butler, LaToya; Gay, Claudy; Scott, Kiandra; Baldwin, William S

    2014-11-15

    Most nuclear receptors (NRs) are ligand-dependent transcription factors crucial in homeostatic physiological responses or environmental responses. We annotated the Daphnia magna NRs and compared them to Daphnia pulex and other species, primarily through phylogenetic analysis. Daphnia species contain 26 NRs spanning all seven gene subfamilies. Thirteen of the 26 receptors found in Daphnia species phylogenetically segregate into the NR1 subfamily, primarily involved in energy metabolism and resource allocation. Some of the Daphnia NRs, such as RXR, HR96, and E75 show strong conservation between D. magna and D. pulex. Other receptors, such as EcRb, THRL-11 and RARL-10 have diverged considerably and therefore may show different functions in the two species. Curiously, there is an inverse association between the number of NR splice variants and conservation of the LBD. Overall, D. pulex and D. magna possess the same NRs; however not all of the NRs demonstrate high conservation indicating the potential for a divergence of function.

  3. Cloning and expression analysis of a transformer gene in Daphnia pulex during different reproduction stages.

    PubMed

    Chen, Ping; Xu, Shan-Liang; Zhou, Wei; Guo, Xiao-Ge; Wang, Chun-Lin; Wang, Dan-Li; Zhao, Yun-Long

    2014-05-01

    The full-length cDNA of a transformer gene (Dptra) was cloned from the cladoceran Daphnia pulex using RACE. Dptra expression was assessed by qPCR and whole-mount in situ hybridization in different reproductive stages. The Dptra cDNA, 1652bp in length, has a 1158-bp open reading frame that encodes a 385 amino acid polypeptide containing one Sex determination protein N terminal (SDP_N) superfamily, eight putative phosphorylation sites, and an arginine-serine (RS)-rich domain at the N-terminus. Dptra showed 81%, 53%, 51% and 45% identity to orthologous genes in Daphnia magna, Apis mellifera, Apis cerana and Bombus terrestris, respectively. Phylogenetic analysis based on deduced amino acid sequences revealed that Dptra clustered in the hymenopteran clade and was most closely related to D. magna and A. mellifera. qPCR showed that Dptra expression increased significantly (P<0.05) in different reproductive stages in the following order: male, ephippial female, parthenogenetic female, resting egg and juvenile female. Dptra expression is significantly different between males and females and it is significantly greater in ephippial females and males than in parthenogenetic D. pulex (with summer eggs). Whole-mount in situ hybridization revealed that Dptra was expressed at different levels between males and females. In males, hybridization signals were found in the first antennae, second antennae and thoracic limb, whereas expression levels in the corresponding sites of parthenogenetic and ephippial females were relatively weak. This suggests that the Dptra gene plays significant roles in switching modes of reproduction and in sexual differentiation.

  4. Acute toxicity of PCB congeners to Daphnia magma and Pimephales promelas

    SciTech Connect

    Dillon, T.M. ); Burton, W.D.S. )

    1991-02-01

    The acute toxicity (EC50/LC50) of commercial PCB mixtures has been reported to range from 2.0 to 283 ug/L. Because PCBs are very hydrophobic most biological studies have utilized a carrier solvent to facilitate introduction of PCBs into aqueous solution. As a result, biological effects are often reported at exposure concentrations exceeding water solubility. The purpose of this work was to evaluate the comparative toxicity of selected PCB congeners without carrier solvents. These tests were conducted on early life stages of two sensitive freshwater organisms, Daphnia magna and Pimephales promelas.

  5. Assessing the chronic toxicity of atrazine, permethrin, and chlorothalonil to the cladoceran Ceriodaphnia cf. dubia in laboratory and natural river water.

    PubMed

    Phyu, Yin Latt; Palmer, C G; Warne, M St J; Dowse, R; Mueller, S; Chapman, J; Hose, G C; Lim, R P

    2013-04-01

    The majority of ecotoxicological data are generated from standard laboratory-based experiments with organisms exposed in nonflowing systems using highly purified water, which contains very low amounts of dissolved organic matter and suspended particulates. However, such experimental conditions are not ecologically relevant. Thus, there is a need to develop more realistic approaches to determining toxicity, including both lethal and sublethal effects. This research provides information on the effect of natural water constituents, such as suspended particulates and dissolved organic matter, in river water (RW) on the chronic toxicity (7-day reproductive impairment) of the pesticides atrazine, chlorothalonil, and permethrin to the freshwater cladoceran Ceriodaphnia cf. dubia. Standard bioassays were conducted under standard laboratory and more environmentally realistic conditions (using RW). The 7-day IC25 (reproduction impairment) values of atrazine, chlorothalonil, and permethrin to C. cf. dubia ranged from 862.4 to >1000, 51.3 to 66.4, and 0.19 to 0.23 μg/L, respectively. Using the Globally Harmonized System of Classification and Labelling of Chemicals, atrazine is classified as moderately to highly toxic, whereas permethrin and chlorothalonil were both highly toxic. The presence of dissolved organic matter and suspended particles in natural RW did not significantly (p > 0.05) change the toxicity of any of the pesticides to C. cf. dubia compared with that tested in laboratory water (LW). For the tested pesticides, toxicity testing in LW provided an adequate estimate of the hazard posed.

  6. Death by indigestion? Particle binding of contaminants by algae and dietary uptake by Daphnia

    SciTech Connect

    Taylor, G.J.; Baird, D.J.; Soares, A.M.V.M.

    1995-12-31

    Freshwater algae, as with all suspended particulate matter in the water column, exhibit a net negative charge, which results in an affinity for positively charged species, such as toxic metal cations. Such cations will readily adsorb to algal cell surfaces, particularly at low metal concentrations. Work conducted to date, with cadmium and cells of the green algae Chlorella vulgaris, has shown that there are two contrasting effects produced by the particulate adsorption of cadmium on the toxicity of the metal to Daphnia. At sub-lethal concentrations of cadmium, the ingestion of algal cells by Daphnia is inhibited, resulting in reduced growth and reproduction. Experiments comparing the effect of algal bound and free ionic forms of cadmium demonstrate that this inhibition is almost entirely due to the surface bound fraction. However, at free cadmium concentrations that are lethal to Daphnia, algal cells were found to reduce toxicity. Further studies using slow-motion video analysis of tethered animals have confirmed this, by showing that algal-bound cadmium produces a more rapid and severe feeding inhibition response than free cadmium. These results raise several questions for ecotoxicology. Does the contrasting role of algal cells in increasing toxicity at sub-lethal levels, while reducing toxicity at lethal levels call into question the common assumption that a mechanistic link exists between acute and chronic toxicity? How can this phenomenon be controlled in laboratory experiments? How will the surface binding of contaminants in the field affect the extrapolation of laboratory results to the natural environment?

  7. Development of a Daphnia magna DNA microarray for evaluating the toxicity of environmental chemicals.

    PubMed

    Watanabe, Hajime; Takahashi, Eri; Nakamura, Yuko; Oda, Shigeto; Tatarazako, Norihisa; Iguchi, Taisen

    2007-04-01

    Toxic chemical contaminants have a variety of detrimental effects on various species, and the impact of pollutants on ecosystems has become an urgent issue. However, the majority of studies regarding the effects of chemical contaminants have focused on vertebrates. Among aquatic organisms, Daphnia magna has been used extensively to evaluate organism- and population-level responses of invertebrates to pollutants in acute toxicity or reproductive toxicity tests. Although these types of tests can provide information concerning hazardous concentrations of chemicals, they provide no information about their mode of action. Recent advances in molecular genetic techniques have provided tools to better understand the responses of aquatic organisms to pollutants. In the present study, we adapted some of the techniques of molecular genetics to develop new tools, which form the basis for an ecotoxicogenomic assessment of D. magna. Based on a Daphnia expressed sequence tag database, we developed an oligonucleotide-based DNA microarray with high reproducibility. The DNA microarray was used to evaluate gene expression profiles of neonatal daphnids exposed to several different chemicals: Copper sulfate, hydrogen peroxide, pentachlorophenol, or beta-naphthoflavone. Exposure to these chemicals resulted in characteristic patterns of gene expression that were chemical-specific, indicating that the Daphnia DNA microarray can be used for classification of toxic chemicals and for development of a mechanistic understanding of chemical toxicity on a common freshwater organism.

  8. The complete mitochondrial genome of the Chinese Daphnia pulex (Cladocera, Daphniidae)

    PubMed Central

    Geng, Xuexia; Cheng, Ruixue; Xiang, Tianyi; Deng, Bin; Wang, Yaling; Deng, Daogui; Zhang, Haijun

    2016-01-01

    Abstract Daphnia pulex has played an important role in fresh-water ecosystems. In this study, the complete mitochondrial genome of Daphnia pulex from Chaohu, China was sequenced for the first time. It was accomplished using long-PCR methods and a primer-walking sequencing strategy with genus-specific primers. The mitogenome was found to be 15,306 bp in length. It contained 13 protein-coding genes, two rRNA genes, 22 tRNA genes and a typical control region. This research revealed an overall A+T content of 64.50%. All of the 22 typical animal tRNA genes had a classical clover-leaf structure except for trnS1, in which its DHU arm simply formed a loop. The lengths of small and large rRNA were 744 bp and 1,313 bp, respectively. The A+T-rich region was 723 bp in length, which is longer than that from the North American species (689 bp). In terms of structure and composition, many similarities were found between the Chinese and North American Daphnia pulex. PMID:27667940

  9. Increased risk of phosphorus limitation at higher temperatures for Daphnia magna.

    PubMed

    Persson, Jonas; Wojewodzic, Marcin Włodzimierz; Hessen, Dag Olav; Andersen, Tom

    2011-01-01

    Invertebrate herbivores frequently face growth rate constraints due to their high demands for phosphorus (P) and nitrogen (N). Temperature is a key modulator of growth rate, yet the interaction between temperature and P limitation on somatic growth rate is scarcely known. To investigate this interaction, we conducted a study on the somatic growth rate (SGR) of the cladoceran Daphnia magna, known to be susceptible to P-limitation. We determined the SGR across a broad range of dietary P content of algae (carbon (C):P ratios (125-790), and at different temperatures (10-25°C). There was a strong impact of both temperature and C:P ratio on the SGR of D. magna, and also a significant interaction between both factors was revealed. The negative effect of dietary C:P on growth rate was reduced with decreased temperature. We found no evidence of P limitation at lowest temperature, suggesting that enzyme kinetics or other measures of food quality overrides the demands for P to RNA and protein synthesis at low temperatures. These findings also indicate an increased risk of P limitation and thus reduced growth efficiency at high temperatures.

  10. Effect of carbaryl (carbamate insecticide) on acetylcholinesterase activity of two strains of Daphnia magna (Crustacea, Cladocera).

    PubMed

    Toumi, Hela; Bejaoui, Mustapha; Touaylia, Samir; Burga Perez, Karen F; Ferard, Jean François

    2016-11-01

    The present study was designed to investigate the effect of carbaryl (carbamate insecticide) on the acetylcholinesterase activity in two strains (same clone A) of the crustacean cladoceran Daphnia magna. Four carbaryl concentrations (0.4, 0.9, 1.8 and 3.7 µg L(-1)) were compared against control AChE activity. Our results showed that after 48 h of carbaryl exposure, all treatments induced a significant decrease of AChE activities whatever the two considered strains. However, different responses were registered in terms of lowest observed effect concentrations (LOEC: 0.4 µg L(-1) for strain 1 and 0.9 µg L(-1) for strains 2) revealing differences in sensitivity among the two tested strains of D. magna. These results suggest that after carbaryl exposure, the AChE activity responses can be also used as a biomarker of susceptibility. Moreover, our results show that strain1 is less sensitive than strain 2 in terms of IC50-48 h of AChE activity. Comparing the EC50-48 h of standard ecotoxicity test and IC50-48 h of AChE inhibition, there is the same order of sensitivity with both strains.

  11. Toxicity of inorganic and organic selenium to Daphnia magna (cladocera) and Chironomus riparius (diptera)

    USGS Publications Warehouse

    Ingersoll, Christopher G.; Dwyer, F.J.; May, T.W.

    1990-01-01

    Elevated concentrations of selenium (Se) have been previously measured in biota sampled from the Kesterson National Wildlife Refuge (KNWR) in the San Joaquin Valley of central California. We conducted acute and chronic toxicity tests with the cladoceran Daphnia magna and the midge Chironomus riparius to determine the toxicity or bioaccumulation of waterborne Se in a reconstituted water similar to the San Joaquin River. Daphnids were more acutely sensitive than midges to the toxic effects of inorganic Se. An organic form of Se (seleno-[L]-methionine) was extremely toxic to daphnids, but was relatively nontoxic to midges. In long-term exposure to a 6:1 mixture of selenate to selenite (a mixture representative of KNWR), the emergence time of adult midges was delayed at Se concentrations ≥ 837 μg/L. Daphnid reproduction and intrinsic rate of natural increase (r) were reduced at Se concentrations ≥ 348 μg/L and growth of adults was reduced at ≥ 156 μg/L. Whole body Mg, K and Na concentrations in daphnids were not affected by chronic Se exposure; however, whole body Ca concentration increased at intermediate Se exposure concentrations. In addition, whole body Cl concentration was reduced at 711 μg Se/L. Daphnids accumulated potentially toxic concentrations of Se from water that may adversely affect fish or waterfowl through the food chain.

  12. A mechanistic model of contaminant-induced feeding inhibition in Daphnia magna

    SciTech Connect

    Allen, Y.; Calow, P.; Baird, D.J.

    1995-09-01

    Particles in water ubiquitously carry a net negative charge. It was hypothesized that the interaction between suspended particles and pollutants in water results in a process of adsorption that can be related to the charge of the pollutant concerned, and that this is a potential route of pollutant uptake by aquatic animals such as particle-grazing zooplankton. Experiment with the alga Chlorella vulgaris were conducted to test the hypotheses that pollutant-induced feeding inhibition in the cladoceran Daphnia magna was dependent on this mechanism. Using compounds differing in charge, results supported the hypothesis that, while all compounds were capable of causing feeding inhibition, electropositive species such as cadmium induced effects close to the chronic no-effect concentration, whereas electronegative species such as vanadium induced effects only at or close to lethal levels. It was suggested that for those compounds capable of causing feeding inhibition at sublethal concentrations, this inhibition would be a key mechanism impairing reproduction and growth, with potential consequences of grazing animals at population and community levels in natural ecosystems.

  13. Is acetylcholinesterase a biomarker of susceptibility in Daphnia magna (Crustacea, Cladocera) after deltamethrin exposure?

    PubMed

    Toumi, Héla; Boumaiza, Moncef; Millet, Maurice; Radetski, Claudemir Marcos; Felten, Vincent; Férard, Jean François

    2015-02-01

    In the present study, we explored the possibility of using the acetylcholinesterase (AChE) as a biomarker after deltamethrin (pyrethroid insecticide) exposure with three strains of the cladoceran Daphnia magna. Four calculated time-weighted deltamethrin concentrations (20.1, 40.3, 80.6 and 161.3 ng L(-1)) were compared against control acetylcholinesterase activity. Our results showed that after 48 h of deltamethrin exposure, all treatments induced a significant decrease of AChE activities whatever the three considered strains. However, diverse responses were registered in terms of lowest observed effect concentrations (LOEC: 80.6 ng L(-1) for strain 1 and 20.1 ng L(-1) for strains 2 and 3) revealing differences in sensitivity among the three tested strains of D. magna. Our results suggest that after deltamethrin exposure, the AChE activity responses can be also used as a biomarker of susceptibility (i.e., variation of strain specific response). Moreover, our results show that strain 1 is the less sensitive in terms of IC50-48 h of AChE, whereas it became the most sensitive when considering the EC50-48 h estimated in the standard ecotoxicity test.

  14. Production of male neonates in Daphnia magna (Cladocera, Crustacea) exposed to juvenile hormones and their analogs.

    PubMed

    Oda, Shigeto; Tatarazako, Norihisa; Watanabe, Hajime; Morita, Masatoshi; Iguchi, Taisen

    2005-12-01

    We exposed the water flea Daphnia magna (Cladocera, Crustacea) to either juvenile hormone I (JH I), juvenile hormone II (JH II), or the juvenile hormone-mimicking insecticides kinoprene, hydroprene, epofenonane, or fenoxycarb. By 21-day reproduction tests, we investigated the effects on the number of neonates born per female and the offspring sex ratio. All six chemicals induced D. magna to produce male neonates; the male sex ratio of the offspring increased as the chemical concentration increased. EC50 values for production of male neonates were estimated as 400 (JH I), 410 (JH II), 190 (kinoprene), 2.9 (hydroprene), 64 (epofenonane), and 0.92 (fenoxycarb) microg/l. The number of neonates produced was reduced with all chemicals at the concentrations investigated. At the EC50 for male production, five of the six chemicals reduced the reproductive rate to less than 50%; the exception was epofenonane, which caused only a slight reduction in reproductive rate. These results were similar to those obtained for five juvenoids studied previously, one of which was studied here again. There are now 10 chemical substances--all juvenile hormones or their analogs-that are known to induce D. magna to produce male neonates. This suggests that juvenile hormone is involved in initiating male production followed by sexual reproduction in D. magna, and probably in most cladocerans that exhibit cyclic parthenogenesis.

  15. Increased risk of phosphorus limitation at higher temperatures for Daphnia magna

    PubMed Central

    Wojewodzic, Marcin Włodzimierz; Hessen, Dag Olav; Andersen, Tom

    2010-01-01

    Invertebrate herbivores frequently face growth rate constraints due to their high demands for phosphorus (P) and nitrogen (N). Temperature is a key modulator of growth rate, yet the interaction between temperature and P limitation on somatic growth rate is scarcely known. To investigate this interaction, we conducted a study on the somatic growth rate (SGR) of the cladoceran Daphnia magna, known to be susceptible to P-limitation. We determined the SGR across a broad range of dietary P content of algae (carbon (C):P ratios (125–790), and at different temperatures (10–25°C). There was a strong impact of both temperature and C:P ratio on the SGR of D. magna, and also a significant interaction between both factors was revealed. The negative effect of dietary C:P on growth rate was reduced with decreased temperature. We found no evidence of P limitation at lowest temperature, suggesting that enzyme kinetics or other measures of food quality overrides the demands for P to RNA and protein synthesis at low temperatures. These findings also indicate an increased risk of P limitation and thus reduced growth efficiency at high temperatures. PMID:20803219

  16. Reproductive value and the cost of reproduction in Daphnia carinata and Echinisca triserialis (crustacea:cladocera) exposed to food and cadmium stress

    SciTech Connect

    Chandini, T. )

    1991-07-01

    Organisms vary in terms of stopping growth and starting to breed. This is an important criterion for fitness. In the struggle for existence, advantage rests with those organisms which are most efficient in utilizing available energy for reproduction. The Reproductive Value (RV) of any organism can be partitioned into reproduction occurring at the present age (m{sub x}) and that occurring in all subsequent classes which is the Residual Reproductive Value (RRV). Under optimal conditions, the reproductive value will be maximized and any deviations from normal reproductive patterns result in energy expenditure by the organisms, reducing their RV. The present study is a laboratory investigation on the effects of food and cadmium stress on the RV and the RRV of the two cladocerans Echinisca triserialis and Daphnia carinata. The present study also attempts to test the cost of reproduction hypothesis' on whether the energy invested by organisms at a particular time in reproduction could affect their future survival and reproduction.

  17. Freshwater Wetlands.

    ERIC Educational Resources Information Center

    Naturescope, 1986

    1986-01-01

    Provides descriptions about freshwater wetlands, such as marshes, swamps, and bogs. Contains three learning activities which deal with unusual wetland plants, the animals and plants in a typical marsh, and the effects of a draught on a swamp. Included are reproducible handouts and worksheets for two of the activities. (TW)

  18. Effects of acid precipitation on Daphnia magna

    SciTech Connect

    Parent, S.; Cheetham, R.D.

    1980-08-01

    Pollutants derived from fossil fuel combustion and precipitated from the atmosphere have substantially increased in the past decades. These materials, precipitated in such industrialized areas as southeastern Canada, have caused considerable alterations in aquatic ecosystems. Precipitation over most of the eastern United States is presently 10 to 500 times more acidic than is natural. Most affected aquatic ecosystems contain oligotrophic waters in regions of thin poorly buffered soils. Zooplankton are an important link in food chains of aquatic ecosystems and their disappearance or decline could drastically affect trophic relationships. Declines in zooplankton density in response to acid precipitation have been reported and short term survival of Daphnia pulex between pH 4.3 and 10.4; however, its potential for reproduction was limited to a fairly narrow range. Anderson (1944) noted the advantages of using daphnia as test organisms, and concluded that Daphnia magna was representative of other abundant zooplankton in sensitivity to toxic substances.

  19. Climate Effects on High Latitude Daphnia via Food Quality and Thresholds

    PubMed Central

    Przytulska, Anna; Bartosiewicz, Maciej; Rautio, Milla; Dufresne, France; Vincent, Warwick F.

    2015-01-01

    Climate change is proceeding rapidly at high northern latitudes and may have a variety of direct and indirect effects on aquatic food webs. One predicted effect is the potential shift in phytoplankton community structure towards increased cyanobacterial abundance. Given that cyanobacteria are known to be a nutritionally poor food source, we hypothesized that such a shift would reduce the efficiency of feeding and growth of northern zooplankton. To test this hypothesis, we first isolated a clone of Daphnia pulex from a permafrost thaw pond in subarctic Québec, and confirmed that it was triploid but otherwise genetically similar to a diploid, reference clone of the same species isolated from a freshwater pond in southern Québec. We used a controlled flow-through system to investigate the direct effect of temperature and indirect effect of subarctic picocyanobacteria (Synechococcus) on threshold food concentrations and growth rate of the high latitude clone. We also compared the direct effect of temperature on both Daphnia clones feeding on eukaryotic picoplankton (Nannochloropsis). The high latitude clone had a significantly lower food threshold for growth than the temperate clone at both 18 and 26°C, implying adaptation to lower food availability even under warmer conditions. Polyunsaturated fatty acids were present in the picoeukaryote but not the cyanobacterium, confirming the large difference in food quality. The food threshold for growth of the high latitude Daphnia was 3.7 (18°C) to 4.2 (26°C) times higher when fed Synechococcus versus Nannochloropsis, and there was also a significant negative effect of increased temperature and cyanobacterial food on zooplankton fatty acid content and composition. The combined effect of temperature and food quality on the performance of the high latitude Daphnia was greater than their effects added separately, further indicating the potentially strong indirect effects of climate warming on aquatic food web processes. PMID

  20. Climate Effects on High Latitude Daphnia via Food Quality and Thresholds.

    PubMed

    Przytulska, Anna; Bartosiewicz, Maciej; Rautio, Milla; Dufresne, France; Vincent, Warwick F

    2015-01-01

    Climate change is proceeding rapidly at high northern latitudes and may have a variety of direct and indirect effects on aquatic food webs. One predicted effect is the potential shift in phytoplankton community structure towards increased cyanobacterial abundance. Given that cyanobacteria are known to be a nutritionally poor food source, we hypothesized that such a shift would reduce the efficiency of feeding and growth of northern zooplankton. To test this hypothesis, we first isolated a clone of Daphnia pulex from a permafrost thaw pond in subarctic Québec, and confirmed that it was triploid but otherwise genetically similar to a diploid, reference clone of the same species isolated from a freshwater pond in southern Québec. We used a controlled flow-through system to investigate the direct effect of temperature and indirect effect of subarctic picocyanobacteria (Synechococcus) on threshold food concentrations and growth rate of the high latitude clone. We also compared the direct effect of temperature on both Daphnia clones feeding on eukaryotic picoplankton (Nannochloropsis). The high latitude clone had a significantly lower food threshold for growth than the temperate clone at both 18 and 26°C, implying adaptation to lower food availability even under warmer conditions. Polyunsaturated fatty acids were present in the picoeukaryote but not the cyanobacterium, confirming the large difference in food quality. The food threshold for growth of the high latitude Daphnia was 3.7 (18°C) to 4.2 (26°C) times higher when fed Synechococcus versus Nannochloropsis, and there was also a significant negative effect of increased temperature and cyanobacterial food on zooplankton fatty acid content and composition. The combined effect of temperature and food quality on the performance of the high latitude Daphnia was greater than their effects added separately, further indicating the potentially strong indirect effects of climate warming on aquatic food web processes.

  1. Bioavailability of fluoranthene in freshwater sediment toxicity tests

    SciTech Connect

    Suedel, B.C.; Rodgers, J.H. Jr. ); Clifford, P.A. )

    1993-01-01

    To examine equilibrium-partitioning model predictions of interstitial water concentrations of fluoranthene as part of the equilibrium-partitioning (EqP) approach to sediment quality criteria development, the bioavailability (toxicity) of fluoranthene-amended sediment to Hyalella azteca, Daphnia magna, and Chironomus tentans was determined. Fluoranthene was added to three freshwater sediments with similar organic carbon content. Predicted interstitial water concentrations from the equilibrium-partitioning model were similar to measured interstitial water concentrations for WRFS and TR sediment, but the model underpredicted measured values for LF sediment by a factor of two. EC50s for Daphnia magna, Hyalella azteca, and Chironomus tentans in interstitial water were a factor of two to five greater for LF than for WRFS and TR sediments. Factors other than organic carbon content of sediments probably contributed to the variability in bioavailability of fluoranthene. Based on 10-d sediment toxicity tests with Hylella azteca, Daphnia magna, and Chironomus tentans, organic carbon-normalized sediment concentrations were better predictors of toxicity than interstitial water and bulk sediment fluoranthene concentrations. In 10-d aqueous-phase tests with fluoranthene, Chironomus tentans and Hyalella azteca were twice as sensitive as Daphnia magna.

  2. Surface binding of contaminants by algae: Consequences for lethal toxicity and feeding to Daphnia magna straus

    SciTech Connect

    Taylor, G. |; Baird, D.J.; Soares, A.M.V.M.

    1998-03-01

    Freshwater algae, as with all suspended particulate matter in the water column, exhibit a net negative charge resulting in an affinity for positively charged species, such as toxic metal cations, which will readily adsorb to algal cell surfaces. In this study, the adsorption of a representative toxic metal cadmium cation (Cd{sup 2+}) to a freshwater algal species, Chlorella vulgaris, was investigated using environmentally realistic concentrations of both. A further study of the effects of this particulate adsorption of Cd{sup 2+} on lethal toxicity and feeding in Daphnia magna was conducted. Two apparently contrasting effects were observed. For the D. magna feeding study, cell ingestion was inhibited, leading to reduced growth and reproduction. Experiments comparing the effect of algal-bound cadmium and dissolved forms of cadmium demonstrate that this inhibition is almost entirely due to the surface-bound fraction of ions. However, at concentrations of dissolved cadmium that are lethal to Daphnia, algal cells were found to reduce toxicity. Such findings indicate the importance of food ration in laboratory-based toxicity tests as well as the difficulty in predicting the environmental fate and effect of contaminants using such tests.

  3. Spectral absorbance of benthic cladoceran carapaces as a new method for inferring past UV exposure of aquatic biota

    NASA Astrophysics Data System (ADS)

    Nevalainen, Liisa; Rautio, Milla

    2014-01-01

    We developed a method for measuring fossil cladoceran (Branchiopoda) carapace absorbance to infer past ultraviolet radiation (UV) exposure in lakes. This was done under the presumptions that cladocerans synthesize photoprotective compounds, of which melanin is the main UV-absorbing pigment, to their exoskeletons and melanin is preserved in sedimentary cladoceran remains. We extracted large-sized cladoceran (benthic Alona spp.) carapaces from subsections of sediment cores from two environmentally divergent lakes; a humic boreal forest lake in eastern Finland (past 1500 years) and a clear-water mountain lake in the Austrian Alps (past 300 years). We measured the absorbance of extracted carapaces with a spectrophotometer under visible light and UV wavelengths using an adapter, which was designed to hold the microfossils. When compared to the spectrum of synthetic melanin, the shapes of absorbance spectra at the 700-280 nm range suggested that the fossil carapaces contained melanin. The carapace absorbance under UV throughout the sediment cores was significantly higher in the clear-water alpine lake than in the humic boreal lake reflecting differences in the general underwater UV and optical environments between the sites. In addition, carapace absorbance was significantly higher during the Little Ice Age (LIA) than during pre- or post-LIA periods in both lakes. In the alpine lake, this was most likely a response to increased underwater UV induced by reduced primary production and more transparent water column during the cold summers of LIA, whereas reduced input of carbon compounds from the catchment through elongated permafrost and ice-cover periods likely induced higher water transparency in the boreal lake during this cold climate phase. We conclude that fossil melanin provides a good estimation of past underwater UV exposure in lakes with large cladoceran carapaces preserved in sediments and that the method introduced here is easy and cost- and time

  4. In situ toxicity testing with locally collected Daphnia

    SciTech Connect

    Snyder-Conn, E.

    1993-07-01

    Daphnia middlendorffiana from local tundra ponds were transplanted into five reserve pits (sumps with used drilling wastes and precipitation) at drill sites in the Prudhoe Bay oil field. Concurrently, Daphnia were transplanted into tundra ponds adjacent to the reserve pits (near ponds), into more distant but connected ponds (distant ponds), and into control ponds to evaluate the toxicity of the fluids along contaminant gradients. Twenty adult Daphnia were placed in eight waxed flow-through containers and exposed to the conditions of each test site. In each exposure container, the ratios of the number of dead Daphnia to the total number of adult Daphnia, the number of young Daphnia to the total number of adult Daphnia, the number of molting Daphnia to the total number of adult Daphnia, and the number of released ephippia to the total number of adult Daphnia were determined. The results not only indicate the utility of in situ testing of invertebrate toxicity but suggest that under certain conditions in situ tests may be more sensitive than traditional laboratory toxicity tests.

  5. Biotransformation and bioconcentration of pyrene in Daphnia magna.

    PubMed

    Akkanen, Jarkko; Kukkonen, Jussi V K

    2003-06-19

    Water fleas (Daphnia magna) were exposed to [14C]pyrene in the presence and absence of piperonyl butoxide (PBO), a general cytochrome P450 (CYP) inhibitor, in organic carbon-free artificial freshwater (AFW, DOC<0.2 mg l(-1)) and in natural lake water (DOC=19.9 mg l(-1)) for 24 h. The bioconcentration of total radioactivity after 24 h exposure was 50% lower in the natural lake water, indicating decreased bioavailability of pyrene by the dissolved organic matter. However, the proportions of parent compound were only ca. 12 and 19% of the total body burden in daphnids exposed in AFW and natural lake water, respectively. Therefore, the tissue concentration of the parent pyrene was not significantly different in the daphnids exposed in the two different waters. Due to extensive biotransformation the bioconcentration factor (BCF) of parent pyrene was only 16 and 23% of the BCF calculated on the basis of total radioactivity in the daphnids in AFW and natural lake water, respectively. The proportion of parent pyrene was significantly higher (over 60%) in the daphnids exposed simultaneously to PBO, which indicates the involvement of CYP monooxygenases in the biotransformation. Furthermore, increasing PBO concentration decreased the accumulation of total radioactivity in AFW but not in the natural lake water. The data demonstrate capability and importance of CYP monooxygenases in biotransformation of polycyclic aromatic hydrocarbons in D. magna.

  6. Acute and chronic toxicity of veterinary antibiotics to Daphnia magna.

    PubMed

    Wollenberger, L; Halling-Sørensen, B; Kusk, K O

    2000-04-01

    The acute and chronic toxicity of nine antibiotics used both therapeutically and as growth promoters in intensive farming was investigated on the freshwater crustacean Daphnia magna. The effect of the antibiotics metronidazole (M), olaquindox (OL), oxolinic acid (OA), oxytetracycline (OTC), streptomycin (ST), sulfadiazine (SU), tetracycline (TC), tiamulin (TI) and tylosin (TY) was tested in accordance to the ISO (1989) and OECD (1996) standard procedures. The acute toxicities (48-h EC50 value, mg/l) in decreasing order were OA (4.6), TI (40), SU (221), ST (487), TY (680) and OTC (approximately 1000). NOECs were 340 mg/l for TC and 1000 mg/l for M and OL. Toxic effect on reproduction occurred generally at concentrations, which were one order of magnitude below the acute toxic levels. The chronic toxicity (EC50 values, mg/l) in the D. magna reproduction test in decreasing order were TI (5.4), SU (13.7), TC (44.8) and OTC (46.2). The NOECs (mg/l) obtained in the reproduction test with OA, ST, TY and M were 0.38 for OA, 32 for ST, 45 for TY and 250 for M. The observed toxicity of OA to D. magna indicates that this substance, which is a commonly used feed additive in fish farms, has a potential to cause adverse effects on the aquatic environment.

  7. Methods For Collecting , Culturing And Performing Toxicity Tests With Daphnia ambigua

    SciTech Connect

    Specht, Winona L.

    2005-07-01

    Toxicity tests conducted on water collected from impacted locations in SRS streams often failed chronic toxicity tests and sometimes failed acute toxicity tests (Specht 1995). These findings prompted SRS to determine the cause of the failures. Some SRS NPDES outfalls were also failing chronic toxicity tests, even though no toxicant could be identified and when TIEs were performed, none of the TIE treatments removed the toxicity. Ultimately, it was determined that the failures were due to the low hardness of SRS surface waters, rather than to the presence of a toxicant. The species of cladoceran that the EPA recommends for toxicity testing, Ceriodaphnia dubia, is stressed by the very low hardness of SRS waters. SRS developed an alternate species toxicity test that is similar to the EPA test, but uses an indigenous cladoceran, Daphnia ambigua (Specht and Harmon, 1997; Harmon et al., 2003). In 2001, SCDHEC approved the use of D. ambigua for toxicity testing at SRS, contingent upon approval by EPA Region 4. In 2002, EPA Region 4 approved the use of this species for compliance toxicity testing at SRS. Ultimately, the use of this species demonstrated that SRS effluents were not toxic, and most toxicity testing requirements were removed from the NPDES permit that was issued in December 2003, with the exception of one round of chronic definitive testing on outfalls A-01, A-11, and G-10 just before the next NPDES permit application is submitted to SCDHEC. Although the alternate species test was developed at SRS (1996-1998), the culture was transferred to a contract toxicity testing lab (ETT Environmental) located in Greer, SC in 1998. ETT Environmental became certified by SCDHEC to perform toxicity tests using D. ambigua in 2002, and at this time is the only laboratory certified by SCDHEC to perform tests with this species. Because of the expense associated with maintaining the D. ambigua culture for several years when no toxicity testing is required, SRS decided to suspend

  8. Evaluation of Daphnia ambigua for Routine Aquatic Toxicity Testing at the Savannah River Site

    SciTech Connect

    Specht, W.L.; Harmon, S.M.

    1997-09-01

    Short-term whole effluent toxicity testing, which is currently a requirement of the U.S. EPA`s National Pollution Discharge Elimination System (NPDES), commonly uses the cladoceran species Ceriodaphnia dubia. Despite the advantages to using a common test species to model the toxic effects of effluents, it could be argued that toxicity test results would be more meaningful if a wider variety of test organisms were commonly used. One particular argument against C. dubia is that tests conducted with this species do not always reflect local, site-specific conditions. The careful selection and use of an indigenous test species would produce a more realistic model of local instream effects and would account for regional differences in water quality. Permitted effluent discharges from Savannah River Site (SRS), a government weapons facility operated by the U.S. Department of Energy, require toxicity testing with C. dubia. However, water quality in these receiving streams is markedly different (lower pH and hardness) from standard laboratory water used for the culturing and testing of C. dubia, and it has been shown that this receiving water presents varying degrees of toxicity to C. dubia. Based on these results, it is possible that toxic effects observed during an effluent study could be the result of test organism stress from the dilution water and not the effects of SRS effluents. Therefore, this study addressed the substitution of C. dubia with an indigenous cladoceran species, Daphnia ambigua for routine regulatory testing at SRS. Given the indigenous nature of this species, combined with the fact that it has been successfully cultured by other investigators, D. ambigua was ideal for consideration as a replacement for C. dubia, but further study of the overall success and sensitivity of laboratory-reared D. ambigua was required. This investigation determined that D. ambigua could be laboratory cultured with only minimal changes to established regulatory protocol and

  9. The water flea Daphnia magna (Crustacea, Cladocera) as a test species for screening and evaluation of chemicals with endocrine disrupting effects on crustaceans.

    PubMed

    Tatarazako, Norihisa; Oda, Shigeto

    2007-02-01

    The water flea Daphnia magna (Crustacea, Cladocera) is a cyclical parthenogen, which can reproduce both by parthenogenesis and by sexual reproduction. With its ease of handling in the laboratory, several testing methods using D. magna exist for regulatory toxicity testing. Recently, several studies revealed that one of the major hormone groups in insects and crustaceans, juvenile hormones, are involved in the shift of reproductive mode from parthenogenesis to sexual reproduction (production of male neonates). Using offspring sex ratio as a new endpoint has made it possible to identify chemicals with juvenile hormone-like effects on crustaceans. The testing method using D. magna, in which offspring sex ratio is incorporated as a new endpoint, is now being proposed to the OECD as an enhanced version of the existing OECD Test Guideline 211: Daphnia magna reproduction test. No other clear-cut endpoint for identifying juvenile-hormone disrupting effects has ever been found in crustaceans than the induction of male neonates production in cladocerans. In this regard, it is expected that testing methods using D. magna are suitable for screening and risk assessment of chemicals with juvenile-hormone disrupting effects.

  10. Effect of nutrient limitation of cyanobacteria on protease inhibitor production and fitness of Daphnia magna.

    PubMed

    Schwarzenberger, Anke; Sadler, Thomas; Von Elert, Eric

    2013-10-01

    Herbivore-plant interactions have been well studied in both terrestrial and aquatic ecosystems as they are crucial for the trophic transfer of energy and matter. In nutrient-rich freshwater ecosystems, the interaction between primary producers and herbivores is to a large extent represented by Daphnia and cyanobacteria. The occurrence of cyanobacterial blooms in lakes and ponds has, at least partly, been attributed to cyanotoxins, which negatively affect the major grazer of planktonic cyanobacteria, i.e. Daphnia. Among these cyanotoxins are the widespread protease inhibitors. These inhibitors have been shown (both in vitro and in situ) to inhibit the most important group of digestive proteases in the gut of Daphnia, i.e. trypsins and chymotrypsins, and to reduce Daphnia growth. In this study we grew cultures of the cyanobacterium Microcystis sp. strain BM25 on nutrient-replete, N-depleted or P-depleted medium. We identified three different micropeptins to be the cause for the inhibitory activity of BM25 against chymotrypsins. The micropeptin content depended on nutrient availability: whereas N limitation led to a lower concentration of micropeptins per biomass, P limitation resulted in a higher production of these chymotrypsin inhibitors. The altered micropeptin content of BM25 was accompanied by changed effects on the fitness of Daphnia magna: a higher content of micropeptins led to lower IC50 values for D. magna gut proteases and vice versa. Following expectations, the lower micropeptin content in the N-depleted BM25 caused higher somatic growth of D. magna. Therefore, protease inhibitors can be regarded as a nutrient-dependent defence against grazers. Interestingly, although the P limitation of the cyanobacterium led to a higher micropeptin content, high growth of D. magna was observed when they were fed with P-depleted BM25. This might be due to reduced digestibility of P-depleted cells with putatively thick mucilaginous sheaths. These findings indicate that

  11. Mesozooplankton affinities in a recovering freshwater estuary

    NASA Astrophysics Data System (ADS)

    Chambord, Sophie; Maris, Tom; Colas, Fanny; Van Engeland, Tom; Sossou, Akoko-C.; Azémar, Frédéric; Le Coz, Maïwen; Cox, Tom; Buisson, Laetitia; Souissi, Sami; Meire, Patrick; Tackx, Michèle

    2016-08-01

    Water quality of the Scheldt estuary (Belgium/The Netherlands) has considerably improved in recent years, especially in the upstream, freshwater reaches. Within the zooplankton community, the copepod Eurytemora affinis, typically abundant in brackish water and quasi-absent from freshwater before 2007, has since substantially developed in the latter, where it now represents 90% of the crustacean mesozooplankton community. Simultaneously, cyclopoid copepod abundance has greatly decreased, while cladoceran abundance did not change. The study aim was: 1) to verify if the zooplankton community described for the period 2007-2009 by Mialet et al. (2011) has stabilized until present, and 2) to look for the environmental conditions favouring E. affinis development and causing changes in the upstream freshwater zooplankton community. The 2002-2012 temporal evolution of the zooplankton distribution at three stations in the upstream freshwater Scheldt estuary was analyzed. Water quality remained better after 2007 than before, and some factors revealed continuous improvement in annual mean concentrations (e.g. increase in O2, decrease in BOD5 and NH4sbnd N concentration). The increase in oxygen and the decrease in NH4sbnd N concentration, together with low discharge during summer were the main environmental factors explaining the development and timing of E. affinis in the upstream freshwater reach. In this reach, E. affinis maximal abundance is shifted to higher temperatures (summer) compared to its typical maximum spring abundance peak in the brackish zone of the Scheldt estuary and in most temperate estuaries. The changes in zooplankton community followed a temporal and spatial gradient induced by the spatio-temporal evolution of water quality improvement. The most downstream station (3) allowed E. affinis development (oxygen concentration > 4 mg L-1; NH4sbnd N concentration < 2 mg L-1, discharge (Q) < 50 m3 s-1) from 2007 onwards, and this station showed the highest E

  12. Magnetic characterization of Daphnia resting eggs

    SciTech Connect

    Sakata, Masanobu; Kawasaki, Tamami . E-mail: tamami@rtri.or.jp; Shibue, Toshimichi; Takada, Atsushi; Yoshimura, Hideyuki; Namiki, Hideo

    2006-12-15

    This study characterized the magnetic materials found within Daphnia resting eggs by measuring static magnetization with a superconducting quantum interference device (SQUID) magnetometer, after forming two types of conditions, each of which consists of zero-field cooling (ZFC) and field cooling (FC). Magnetic ions, such as Fe{sup 3+}, contained in Daphnia resting eggs existed as (1) paramagnetic and superparamagnetic particles, demonstrated by a magnetization and temperature dependence of the magnetic moments under an applied magnetic field after ZFC and FC, and (2) ferromagnetic particles with definite magnetic moments, the content of which was estimated to be very low, demonstrated by the Moskowitz test. Conventionally, biomagnets have been directly detected by transmission electron microscopes (TEM). As demonstrated in this study, it is possible to nondestructively detect small biomagnets by magnetization measurement, especially after two types of ZFC and FC. This nondestructive method can be applied in detecting biomagnets in complex biological organisms.

  13. Determinants of Daphnia clonal diversity in lakes

    SciTech Connect

    Kolasa, J.; Mort, M.

    1987-07-01

    Populations of Daphnia show high clonal diversity in large lakes. Hypothetically, this diversity may be maintained by either intrinsic population mechanisms such as reproductive strategies or by structuring properties of habitat such as heterogeneity and associated scale differences. To discriminate between these two classes of factors the authors have applied a predictive hierarchichal model to clone data from 9 northern German lakes (46 clones; N=1236). The model operated reliably by using ecological ranges (a course measure of heterogeneity) of taxa. Concordance of observed patterns and predictions of the model would favor the heterogeneity hypothesis, while the opposite result would suggest greater influence of population-based mechanisms in explaining clonal diversity/abundance patterns. The results of their analysis point towards habitat heterogeneity as the dominant determinant of diversity and abundance structure of Daphnia populations in lakes.

  14. A comparison of the toxicity of 30 reference chemicals to Daphnia magna and Daphnia pulex

    SciTech Connect

    Lilius, H.; Haestbacka, T.; Isomaa, B.

    1995-12-01

    To determine whether significant differences exist in the sensitivity of different Daphnia species to toxicants, the acute toxicity of the first 30 MEIC (multicenter evaluation of in vitro cytotoxicity) reference chemicals was determined in two species of Daphnia: D. magna and D. pulex. Correlation and regression analysis of the EC50 data for immobilization showed a very good concordance (r = 0.97, slope = 1.02). A comparison between the EC50 data obtained for D. magna by two laboratories independently for the 50 MEIC chemicals also showed a good concordance (r = 0.93, slope = 0.91). In both comparisons the regression line did not differ significantly from the regression line for a 1:1 regression. The authors conclude that their study, including a set of reference chemicals, indicates that is no difference in the overall sensitivity of the two Daphnia species and the two clones of D. magna.

  15. Seasonal succession of cladocerans and phytoplankton and their interactions in a shallow eutrophic lake (Lake Vela, Portugal)

    NASA Astrophysics Data System (ADS)

    Abrantes, N.; Antunes, S. C.; Pereira, M. J.; Gonçalves, F.

    2006-01-01

    Lake Vela is a polymictic shallow lake exhibiting some characteristics typical of an advanced trophic state, namely, the permanently turbid water, the reduction in biodiversity, and the recurrent occurrence of Cyanobacteria blooms, which occasionally lead to large fish kills. This study was carried out in order to understand the seasonal variation of Lake Vela's phytoplankton and cladoceran communities and their interactions under advanced eutrophic conditions. When comparing our results with general models of plankton succession observed in other temperate and tropical lakes we found some coherence between several seasonal events. Our results suggest that phytoplankton is mainly regulated by nutrients ("bottom-up" effect). However, the warm mediterranean temperatures had an important role in the phytoplankton succession, being responsible for the rapid and intense Cyanobacteria development in spring and summer. Our work also demonstrated that phytoplankton is one of the main factors responsible for the seasonal structure of the community of cladocerans, which are well related to changes in algae diversity and abundance, being the Cyanobacteria having major impact. Moreover, the occurrence of a massive Cyanobacteria bloom during the study, which induced anoxia and consequent fish kill, enhanced the structuring role that fish have on the cladoceran seasonal succession and the effects of this episode in the normal seasonal succession of plankton.

  16. Trophic transfer of paralytic shellfish toxins from the cladoceran (Moina mongolica) to larvae of the fish (Sciaenops ocellatus).

    PubMed

    Jiang, Tian-Jiu; Wang, Da-Zhi; Niu, Tao; Xu, Yi-Xiao

    2007-10-01

    The dynamic transmission and transformation of paralytic shellfish toxins (PSTs) from the toxic dinoflagellate Alexandrium tamarense to the cladoceran Moina mongolica and subsequently to the larvae of the fish Sciaenops ocellatus were investigated under laboratory conditions. The results showed that PSTs could be transferred to S. ocellatus when they preyed on PST-containing M. mongolica. During the experimental period, A. tamarense, M. mongolica and the digestive glands of the fish larvae contained C(1/2) toxins, and the viscera of S. ocellatus contained neoSTX. The proportion of beta toxin (C2) in C(1+2) toxins increased when PSTs were transferred from A. tamarense to M. mongolica, but in the subsequent transfer from M. mongolica to S. ocellatus the proportion of alpha toxin (C1) increased. During depuration, the contents of C1 and C2 toxins in fish larvae decreased with the duration of depuration, but neoSTX remained relatively constant. The present results indicated that, using a cladoceran as the vector, PSTs can be transferred from toxic algae to a high trophic level fish and metabolized in the fish. Future work should address the metabolic characteristics of PSTs in cladocerans and the end result when they are transferred to fishes.

  17. Environmental boundaries of marine cladoceran distributions in the NW Mediterranean: Implications for their expansion under global warming

    NASA Astrophysics Data System (ADS)

    Atienza, Dacha; Sabatés, Ana; Isari, Stamatina; Saiz, Enric; Calbet, Albert

    2016-12-01

    We studied the horizontal and vertical distributions of marine cladocerans across the Catalan Sea shelf (NW Mediterranean) in July and September 2003, and in June and July 2004. At the seasonal scale, Penilia avirostris appears first in June in the southern region, where temperatures are warmer, and its populations develop northward during the summer. Evadne-Pseudevadne did not show a clear pattern, likely because several species were pooled. In 2003 successive heat waves affecting southwestern Europe resulted in surface seawater temperatures about 2 °C higher than usual across the whole study region. These high temperatures were associated with much lower abundance of P. avirostris. Overall, the mesoscale distributions of cladocerans were associated with the presence of low salinity, productive and stratified waters of continental origin, and negatively linked to the intrusion of offshore waters. On the vertical scale P. avirostris was located within or above the thermocline, whereas Evadne-Pseudevadne was much shallower; no evidence of diel migration was detected in either group. Our study provides new insights regarding the environmental limits for marine cladocerans in the NW Mediterranean; in the particular case of P. avirostris that knowledge can define the likely boundaries of its new distributions as it expands poleward under climate change.

  18. Molecular mechanisms of tolerance to cyanobacterial protease inhibitors revealed by clonal differences in Daphnia magna.

    PubMed

    Schwarzenberger, Anke; Kuster, Christian J; Von Elert, Eric

    2012-10-01

    Protease inhibitors of primary producers are a major food quality constraint for herbivores. In nutrient-rich freshwater ecosystems, the interaction between primary producers and herbivores is mainly represented by Daphnia and cyanobacteria. Protease inhibitors have been found in many cyanobacterial blooms. These inhibitors have been shown (both in vitro and in situ) to inhibit the most important group of digestive proteases in the daphnid's gut, that is, trypsins and chymotrypsins. In this study, we fed four different Daphnia magna genotypes with the trypsin-inhibitor-containing cyanobacterial strain Microcystis aeruginosa PCC 7806 Mut. Upon exposure to dietary trypsin inhibitors, all D. magna genotypes showed increased gene expression of digestive trypsins and chymotrypsins. Exposure to dietary trypsin inhibitors resulted in increased activity of chymotrypsins and reduced activity of trypsin. Strong intraspecific differences in tolerance of the four D. magna genotypes to the dietary trypsin inhibitors were found. The degree of tolerance depended on the D. magna genotype. The genotypes' tolerance was positively correlated with the residual trypsin activity and the different IC(50) values of the trypsins. On the genetic level, the different trypsin loci varied between the D. magna genotypes. The two tolerant Daphnia genotypes that both originate from the same lake, which frequently produces cyanobacterial blooms, clustered in a neighbour-joining phylogenetic tree based on the three trypsin loci. This suggests that the genetic variability of trypsin loci was an important cause for the observed intraspecific variability in tolerance to cyanobacterial trypsin inhibitors. Based on these findings, it is reasonable to assume that such genetic variability can also be found in natural populations and thus constitutes the basis for local adaptation of natural populations to dietary protease inhibitors.

  19. Predator-induced defences in Daphnia longicephala: location of kairomone receptors and timeline of sensitive phases to trait formation.

    PubMed

    Weiss, Linda C; Leimann, Julian; Tollrian, Ralph

    2015-09-01

    The freshwater crustacean Daphnia adapts to changing predation risks by forming inducible defences. These are only formed when they are advantageous, saving associated costs when the defence is superfluous. However, in order to be effective, the time lag between the onset of predation and the defence formation has to be short. Daphnia longicephala develop huge protective crests upon exposure to chemical cues (kairomones) from its predator the heteropteran backswimmer Notonecta glauca. To analyse time lags, we determined kairomone-sensitive stages and the developmental time frames of inducible defences. Moreover, we looked at additive effects that could result from the summation of prolonged kairomone exposure. Kairomones are perceived by chemoreceptors and integrated by the nervous system, which alters the developmental program leading to defence formation. The underlying neuronal and developmental pathways are not thoroughly described and surprisingly, the location of the kairomone receptors is undetermined. We show that D. longicephala start to sense predator cues at the onset of the second juvenile instar, defences develop with a time lag of one instar and prolonged kairomone exposure does not impact the magnitude of the defence. By establishing a method to reversibly impair chemosensors, we show the first antennae as the location of kairomone-detecting chemoreceptors. This study provides fundamental information on kairomone perception, kairomone-sensitive stages, developmental time frames and lag times of inducible defences in D. longicephala that will greatly contribute to the further understanding of the neuronal and developmental mechanisms of predator-induced defences in Daphnia.

  20. Can the teleconnection indices explain the interannual variability of Daphnia phenology ? A case study in Lake Iseo, northern Italy.

    NASA Astrophysics Data System (ADS)

    Beluzzi, Stefano; Leoni, Barbara; Salmaso, Nico; Manca, Marina

    2013-04-01

    In the last years, increasing interest has been shown on the impact of inter-annual climate variability on zooplankton. Several teleconnection indices have been successfully applied in order to explain inter-annual variations in zooplankton and phytoplankton seasonal dynamics. During the winter months (December-February), the East Atlantic pattern (EADJF) and the Eastern Mediterranean Pattern (EMPDJF) showed a clear relationship with the variables directly connected with the winter climate and limnological variables in the large lakes south of the Alps. A recent study carried out in the lakes Maggiore and Garda confirmed that the impact of the winter large scale atmospheric patterns was detectable also on the phenology of Daphnia populations. We extended the same approach to zooplankton of Lake Iseo, the fourth largest and deepest italian lake, with costant characteristic of meso-eutrophy during last decades. We analysed data from 1998 to 2012, focusing on population dynamics of Daphnia sp., the most important larger filter feeder in this lake. The results showed a link between the interannual climate fluctuations and the development of Daphnia. Our observations are consistent with the patterns obtained in the lakes Maggiore and Garda. Overall, the results confirm that these indices may help to detect and predict the effect of the impact of climate change on populations and freshwater ecosystems.

  1. No Evidence for Activity Adjustment in Response to Increased Density in Daphnia magna

    PubMed Central

    Sereni, Laura; Einum, Sigurd

    2015-01-01

    Increased population density may lead to a decrease in energy available for growth and reproduction via effects on the activity level of individuals. Whilst this may be of particular importance for organisms that compete for defendable resources and/or have a high frequency of social interactions, it is less obvious how individual activity should covary with population density when food resources are not defendable or direct interactions among individuals are negligible. Based on observations that there is a general negative relationship between population density and metabolism it has been suggested that organisms actively reduce activity under increased density to accommodate an expected decrease in food availability. However, in the absence of direct activity measurements the validity of this hypothesis is unclear. Here we test for such anticipatory adjustments of activity levels in the planktonic cladoceran Daphnia magna Straus, a filter feeder whose food resources are not defendable, meaning that density responses can be evaluated in the absence of direct interactions. We tested for changes in activity in response to two separate density cues, one being the direct physical and visual stimuli resulting from being in the vicinity of conspecifics (‘direct density experiment’), and the other being the detection of olfactory cues in their environment (‘olfactory cue experiment’). Ten genetically distinct clones were used to evaluate the potential for genetic variation in these responses. Our measures of activity were highly repeatable, and there was significant variation in activity among clones. Furthermore, this clonal variation was consistent in the ‘direct density’ and ‘olfactory cue’ experiments. The estimated evolvability of the trait (1.3–3.2%) was within the range typically observed in behavioural traits. However, there was no indication that the activity level of individuals respond to population density, either directly to actual density

  2. Genetic Diversity of Daphnia pulex in the Middle and Lower Reaches of the Yangtze River

    PubMed Central

    Wang, Wenping; Zhang, Kun; Deng, Daogui; Zhang, Ya-Nan; Peng, Shuixiu; Xu, Xiaoxue

    2016-01-01

    Increased human activities and environmental changes may lead to genetic diversity variations of Cladocerans in water. Daphnia pulex are distributed throughout the world and often regarded as a model organism. The 16S rDNA, cytochrome c oxidase subunit I (COI), and 18S genes were used as molecular marks. The genetic diversity and phylogeny of D. pulex obtained from 10 water bodies in the middle and lower reaches of the Yangtze River were studied. For 16S rDNA, COI gene, and 18S gene, the A+T content (65.4%, 58.4%, and 54.6%) was significantly higher than the G+C content (34.6%, 41.6% and 45.4%). This result was consistent with higher A and T contents among invertebrates. Based on the genetic distances of 16S rDNA and COI genes, the genetic differences of D. pulex from 10 water bodies located in the middle and lower reaches of the Yangtze River in China was minimal (0%–0.8% for 16S rDNA and 0%–1.5% for COI gene). However, D. pulex evolved into two branches in the phylogenetic trees, which coincided with its geographical distribution. Compared with D. pulex from other countries, the average genetic distance of D. pulex obtained from 10 water bodies in the middle and lower reaches of the Yangtze River reached 9.1%–10.5%, thereby indicating that D. pulex may have evolved into different subspecies. PMID:27015539

  3. Chronic toxicity of a homologous series of alcohol ethoxylate surfactants to Daphnia magna

    SciTech Connect

    Gillespie, W.B. Jr.; Rodgers, J.H. Jr.; Wong, D.C.L.; Dorn, P.B.

    1995-12-31

    The effects of three homologous nonionic surfactants were evaluated in a series of 21 d Daphnia magna flow-through laboratory experiments. No observed effects concentrations and effects concentrations for survival and reproduction were determined for three linear alcohol ethoxylate (LAE) surfactants with average carbon chain lengths of 10, 12.5, and 14.5 and average ethylene oxide units/mole of 6, 6.5, and 7, respectively. Mean measured concentrations of LAE in laboratory experiments ranged from 0.91 to 16.91 mg/L, 0.38 to 5.21 mg/L and 0.31 to 1.83 mg/L for C{sub 10}, C{sub 12.5}, and C{sub 14.5} LAEs, respectively. Daphnid survival NOECs were 2.8 mg/L (C{sub 10}), 1.8 mg/L (C{sub 12.5}), and 0.79 mg/L (C{sub 14.5}). Daphnid survival and reproduction were equally sensitive to the C{sub 10} and C{sub 14.5} surfactants, however, reproduction was more sensitive than survival for the C{sub 12.5} surfactant. Reproduction NOECs were 2.8, 0.77, and 0.79 mg/L for the C{sub 10}, C{sub 12.5}, and C{sub 14.5} LAEs, respectively. The 21 d chronic survival NOECs for daphnids were similar to NOECs for cladoceran densities obtained in outdoor stream mesocosm studies conducted at the University of Mississippi Field Station. These results indicate a relationship of approximately 1:1 between the chronic laboratory and field results.

  4. Probabilistic ecological hazard assessment of parabens using Daphnia magna and Pimephales promelas.

    PubMed

    Dobbins, Laura L; Usenko, Sascha; Brain, Richard A; Brooks, Bryan W

    2009-12-01

    Parabens are common antimicrobial agents found in thousands of pharmaceuticals and personal care products. Parabens are introduced into aquatic ecosystems from wastewater treatment plant effluents and have been detected in surface waters in the low microgram per liter range. Although these compounds display low toxicity in mammals, paraben toxicity to aquatic organisms has not been investigated. Standardized acute and subchronic endpoints in larval fish (Pimephales promelas) and cladoceran (Daphnia magna) models were examined for seven different parabens (methyl-, ethyl-, isopropyl-, propyl-, isobutyl-, butyl-, benzylparaben), which encompassed a range of log P values. Paraben 48 h median lethal concentration values (LC50) ranged from 4.0 to 24.6 mg/L in D. magna and 3.3 to >160.0 mg/L in fathead minnow. Growth and reproduction in D. magna had lowest-observed-effect concentrations (LOECs) ranging from 0.12 to 9.0 mg/L and 1.5 to 6.0 mg/L, respectively. Fathead minnow growth was adversely affected at levels ranging from 1.0 to 25.0 mg/L. Aquatic toxicity of the parabens was inversely related to lipophilicity, suggesting that responses using standardized endpoints resulted from narcosis. Utilizing toxicity benchmark concentrations (e.g., LC50s, LOECs) for each compound, chemical toxicity distributions, a probabilistic hazard assessment technique, were developed to assess the probabilities of detecting parabens that elicit a response at or below a given concentration. For the responses assessed in the present study, the 5th centile values (the concentration at which 5% of parabens elicit a response) ranged from 15 microg/L to 2.43 mg/L, with D. magna growth eliciting the lowest 5th centile value and acute D. magna mortality eliciting the highest. The distributions demonstrated that at environmentally relevant concentrations in developed countries there is limited acute or subchronic aquatic hazard of parabens to the organisms and responses examined.

  5. Evaluation of ecotoxicological effects of drugs on Daphnia magna using different enzymatic biomarkers.

    PubMed

    Oliveira, Laira L D; Antunes, Sara C; Gonçalves, Fernando; Rocha, Odete; Nunes, Bruno

    2015-09-01

    The increasing occurrence of pharmaceutical drugs in the aquatic environment is cause of concern, due to the possibility of toxic phenomena in non-target species, including oxidative stress and neurotoxicity. The present study aimed to assess the acute effect of four widely used therapeutic agents: acetaminophen (analgesic), chlorpromazine (antipsychotic), diclofenac (anti-inflammatory) and propranolol (antihypertensive), in the cladoceran species Daphnia magna. Considering the involvement of the mentioned compounds in the impairment of cholinesterasic activity and modifications in cellular redox systems, the purpose of this study was to analyze their effects on biomarkers of neuronal regulation, such as total cholinesterases (ChEs), and enzymatic oxidative stress defense, including as catalase (CAT), glutathione-S-transferases (GSTs), and total and selenium-dependent glutathione-peroxidase (total GPx; Se-GPx) activities. Exposure to acetaminophen caused a significant inhibition of AChE and Se-GPx activities in D. magna relative to the control. Among the biomarkers of oxidative stress, only the activity of CAT was significantly altered in concentration of 0.001mg L(-1) of chlorpromazine, which was not always consistent with the literature. Diclofenac caused a significant inhibition of AChE and Se-dependent GPx, and also in total GPx activities. Propranolol was responsible for a significant decrease in the activity of the latter two enzymes, and also a slight increase of GSTs activity. The results indicated that the exposure to all the tested compounds induced alterations on the cellular redox status in the studied species. In addition, acetaminophen and diclofenac were shown to have the capability of interfering with D. magna neurotransmission, through the inhibition of ChEs. Our data enlighten the need for more research on the ecological consequences of pharmaceuticals in non-target organisms.

  6. Use of Daphnia Magna to Assess Potentially Contaminated Buildings.

    DTIC Science & Technology

    1992-06-01

    Random concrete core samples taken from a loading dock were used in determining the toxicity of concrete to Daphnia magna . The cores were ground to...powder and analyzed for volatiles and chemical agents before being subjected to aquatic toxicology studies using Daphnia magna . Particle size, pH, and

  7. Toxicity and genotoxicity of the quaternary ammonium compound benzalkonium chloride (BAC) using Daphnia magna and Ceriodaphnia dubia as model systems.

    PubMed

    Lavorgna, Margherita; Russo, Chiara; D'Abrosca, Brigida; Parrella, Alfredo; Isidori, Marina

    2016-03-01

    The toxicity and genotoxicity of the cationic surfactant benzalkonium chloride (BAC) were studied using Daphnia magna and Ceriodaphnia dubia as model systems. Acute and chronic toxicity testing were performed according to the international standard guidelines and the genotoxicity was detected through the comet assay on cells from whole organisms in vivo exposed. Acute effects occurred at concentrations in the order of tens of μg/L in D. magna and hundreds of μg/L in C. dubia. Chronic effects were found at one order of magnitude less than short-term effects maintaining the same difference in sensitivity between D. magna and C. dubia. BAC induced relevant DNA damage, in both cladocerans; the lowest adverse effect levels were 0.4 and 4 ng/L for D. magna and C. dubia, respectively. As these effective concentrations are far lower than BAC occurrence in surface waters (units of μg/L) a concerning environmental risk cannot be excluded. The findings of this study showed that D. magna and C. dubia, could be used as model organisms to detect acute and chronic toxicity as well as genotoxicity at the whole organism level.

  8. Toxicity of two types of silver nanoparticles to aquatic crustaceans Daphnia magna and Thamnocephalus platyurus.

    PubMed

    Blinova, Irina; Niskanen, Jukka; Kajankari, Paula; Kanarbik, Liina; Käkinen, Aleksandr; Tenhu, Heikki; Penttinen, Olli-Pekka; Kahru, Anne

    2013-05-01

    Although silver nanoparticles (NPs) are increasingly used in various consumer products and produced in industrial scale, information on harmful effects of nanosilver to environmentally relevant organisms is still scarce. This paper studies the adverse effects of silver NPs to two aquatic crustaceans, Daphnia magna and Thamnocephalus platyurus. For that, silver NPs were synthesized where Ag is covalently attached to poly(vinylpyrrolidone) (PVP). In parallel, the toxicity of collargol (protein-coated nanosilver) and AgNO₃ was analyzed. Both types of silver NPs were highly toxic to both crustaceans: the EC50 values in artificial freshwater were 15-17 ppb for D. magna and 20-27 ppb for T. platyurus. The natural water (five different waters with dissolved organic carbon from 5 to 35 mg C/L were studied) mitigated the toxic effect of studied silver compounds up to 8-fold compared with artificial freshwater. The toxicity of silver NPs in all test media was up to 10-fold lower than that of soluble silver salt, AgNO₃. The pattern of the toxic response of both crustacean species to the silver compounds was almost similar in artificial freshwater and in natural waters. The chronic 21-day toxicity of silver NPs to D. magna in natural water was at the part-per-billion level, and adult mortality was more sensitive toxicity test endpoint than the reproduction (the number of offspring per adult).

  9. Cloning, expression and cellular localization of Daphnia pulex senescence-associated protein, DpSAP.

    PubMed

    Liu, Ajing; Kong, Ling; Zhang, Mingqing; Wu, Donglei; Wang, Danli; Zhao, Yunlong

    2014-01-25

    Daphnia (water fleas) are small crustaceans that undergo an unusual switch from asexual to sexual reproduction that is dependent on environmental conditions. In this study, a senescence-associated protein (SAP) from the common freshwater species Daphnia pulex was cloned using primers based on homologous sequences and rapid amplification of cDNA ends (RACE). Real-time PCR was employed to quantify the expression of D. pulex SAP (DpSAP) in individual organisms. The role of DpSAP in the reproductive transformation was further investigated in both parthenogenetic and sexual females by using digoxin-labeled SAP RNA probes and RNA whole-mount in situ hybridization. DpSAP was more highly expressed in sexual females, indicating a role in growth and reproduction. Cellular localization studies using RNA whole-mount in situ hybridization showed specific expression in the second tentacle joints. These expression patterns suggest an important role for DpSAP in the reproductive transformation of D. pulex.

  10. Chronic toxicity of ibuprofen to Daphnia magna: Effects on life history traits and population dynamics.

    PubMed

    Heckmann, Lars-Henrik; Callaghan, Amanda; Hooper, Helen L; Connon, Richard; Hutchinson, Thomas H; Maund, Steve J; Sibly, Richard M

    2007-08-01

    The non-steroidal anti-inflammatory drug (NSAID) ibuprofen (IB) is a widely used pharmaceutical that can be found in several freshwater ecosystems. Acute toxicity studies with Daphnia magna suggest that the 48h EC(50) (immobilisation) is 10-100 mgIBl(-1). However, there are currently no chronic IB toxicity data on arthropod populations, and the aquatic life impacts of such analgesic drugs are still undefined. We performed a 14-day exposure of D. magna to IB as a model compound (concentration range: 0, 20, 40 and 80 mgIBl(-1)) measuring chronic effects on life history traits and population performance. Population growth rate was significantly reduced at all IB concentrations, although survival was only affected at 80 mgIBl(-1). Reproduction, however, was affected at lower concentrations of IB (14-day EC(50) of 13.4 mgIBl(-1)), and was completely inhibited at the highest test concentration. The results from this study indicate that the long-term crustacean population consequences of a chronic IB exposure at environmentally realistic concentrations (ngl(-1) to microgl(-1)) would most likely be of minor importance. We discuss our results in relation to recent genomic studies, which suggest that the potential mechanism of toxicity in Daphnia is similar to the mode of action in mammals, where IB inhibits eicosanoid biosynthesis.

  11. Ecological constraints on sensory systems: compound eye size in Daphnia is reduced by resource limitation.

    PubMed

    Brandon, Christopher S; Dudycha, Jeffry L

    2014-08-01

    Eye size is an indicator of visual capability, and macroevolutionary patterns reveal that taxa inhabiting dim environments have larger eyes than taxa from bright environments. This suggests that the light environment is a key driver of variation in eye size. Yet other factors not directly linked with visual tasks (i.e., non-sensory factors) may influence eye size. We sought to jointly investigate the roles of sensory (light) and non-sensory factors (food) in determining eye size and ask whether non-sensory factors could constrain visual capabilities. We tested environmental influences on eye size in four species of the freshwater crustacean Daphnia, crossing bright and dim light levels with high and low resource levels. We measured absolute eye size and eye size relative to body size in early and late adulthood. In general, Daphnia reared on low resources had smaller eyes, both absolutely and relatively. In contrast to the dominant macroevolutionary pattern, phenotypic plasticity in response to light was rarely significant. These patterns of phenotypic plasticity were true for overall diameter of the eye and the diameter of individual facets. We conclude that non-sensory environmental factors can influence sensory systems, and in particular, that resource availability may be an important constraint on visual capability.

  12. Toxicity of Vertimec® 18 EC (active ingredient abamectin) to the neotropical cladoceran Ceriodaphnia silvestrii.

    PubMed

    Casali-Pereira, Maressa P; Daam, Michiel A; de Resende, Juliana C; Vasconcelos, Ana M; Espíndola, Evaldo L G; Botta, Clarice M R

    2015-11-01

    The aim of the present study was to evaluate the toxicity of abamectin to the neotropical cladoceran Ceriodaphnia silvestrii. To this end, acute and chronic bioassays were conducted with the commercial formulation Vertimec® 18 EC. In addition, the toxicity of water samples taken from a microcosm experiment evaluating the effects of a single application (144μga.i./L) and two applications (2×36μga.i./L) of Vertimec® 18 EC, in the presence or absence of a tadpole species (Lithobates catesbeianus), was also assessed. The acute LC50-48h for immobilization was 1.47μga.i./L and chronic NOEC-8d for survival and fertility (number of neonates per female) were 169 and 84nga.i./L, respectively. Irrespective of the presence of tadpoles, water samples from the microcosms applied with the single concentration of 144μga.i./L remained toxic until the end of the experiment, even when samples were diluted 32 times with culture medium. Water in the repeated pesticide treatment showed a similar toxic response after both applications. Toxicity of water samples from the microcosms was lower than that expected based on the generated LC50 values, which is explained by a potential reduced bioavailability of the test compound resulting from absorbance to organic material. Potential side-effects on C. silvestrii related with the use of Vertimec® 18 EC in Brazil and the suitability of this species for tropical toxicity testing are discussed.

  13. Acute toxicity of the herbicide bromoxynil to Daphnia magna

    USGS Publications Warehouse

    Buhl, Kevin J.; Hamilton, Steven J.; Schmulbach, James C.

    1993-01-01

    The acute toxicities of technical-grade bromoxynil octanoate (BO) and two commercial formulations, Buctril® and Bronate®, to < 24-h-old neonate Daphnia magna (Straus) were determined in soft, hard, and oligosaline water. In addition, effects of life stage, feeding, aging the herbicide, and exposure duration on BO toxicity to daphnids were investigated. Regardless of formulation, life stage, and water quality, BO was found to be extremely to highly toxic to daphnids in standard tests; 48-h EC50 values ranged from 41 to 161 m̈g/L. Bromoxynil octanoate was the most toxic to neonates in soft water and the least toxic in hard water. The acute toxicities of the three bromoxynil herbicides to a given age group of daphnids were similar within the same water type. Overall, neonates and 7-d-old adults were more sensitive than 14- or 15-d-old adults to each herbicide. Feeding daphnids during the toxicity test significantly decreased BO toxicity compared to not feeding them. Aging BO (as Buctril) in hard water decreased its toxicity, and the rate of deactivation was rapid, with an estimated half-life of biological activity of 13 h. Daphnids immobilized by exposures to toxic BO concentrations for ≤ 6 h recovered their mobility, whereas exposures of 18 and 24 h to BO produced toxic effects in daphnids similar to those exposed for 48 h. These results indicated that standard continuous exposure tests may not adequately predict the acute toxicity of BO to freshwater animals in the field.

  14. Historical metal concentrations in lacustrine food webs revealed using fossil ephippia from Daphnia.

    PubMed

    Wyn, B; Sweetman, J N; Leavitt, P R; Donald, D B

    2007-04-01

    Metal contamination of freshwater ecosystems is increasingly prevalent due to anthropogenic activities such as metal smelting and fossil fuel combustion. While toxicological studies focus on aqueous metal concentrations that result in lethal or sublethal responses, currently the only method for reconstructing a lake's metal contamination history is through an examination of the sedimentary deposits. In this paper, we suggest that cladoceran diapausing eggs (ephippia), which are abundant in nature and accumulate maternally derived metals, can be used to measure historical variations in biologically relevant metals that derive from the water column (water, diet). Linear regressions of total metal content against ephippia density or mass were strong (R2 > 0.80, P < 0.04) and revealed that metals were incorporated into ephippia with little contamination from the sediment matrix. Comparison of metal concentrations in ephippia and bulk sediments from three lakes demonstrated that some metals associated with urban sources (Cd, Cr, Mo) were preferentially concentrated in ephippia, whereas concentrations of other metals indicating landscape erosion (Al, Ca, Fe, Mn) exhibited greater concentrations in bulk sediments than in diapausing eggs. Because historical changes in metals within fossils and bulk sediments were uncorrelated in most instances, past variation in the metal content of ephippia provided a unique history of food web exposure to metals in the water column.

  15. Annotation of the Daphnia magna nuclear receptors: Comparison to Daphnia pulex

    PubMed Central

    Litoff, Elizabeth J; Garriott, Travis E.; Ginjupalli, Gautam K.; Butler, LaToya; Gay, Claudy; Scott, Kiandra; Baldwin, William S.

    2014-01-01

    Most Nuclear Receptors (NRs) are ligand-dependent transcription factors crucial in homeostatic physiological responses or environmental responses. We annotated the D. magna NRs and compared them to D. pulex and other species, primarily through phylogenetic analysis. Daphnia species contain 26 NRs spanning all seven gene subfamilies. Thirteen of the 26 receptors found in Daphnia species phylogenetically segregate into the NR1 subfamily, primarily involved in energy metabolism and resource allocation. Some of the Daphnia NRs, such as RXR, HR96, and E75 show strong conservation between D. magna and D. pulex. Other receptors, such as EcRb, THRL-11 and RARL-10 have diverged considerably and therefore may show different functions in the two species. Curiously, there is an inverse association between the number of NR splice variants and conservation of the LBD. Overall, D. pulex and D. magna possess the same NRs; however not all of the NRs demonstrate high conservation indicating the potential for a divergence of function. PMID:25239664

  16. Development of formulated reference sediments for freshwater and estuarine sediment testing

    SciTech Connect

    Suedel, B.C.; Rodgers, J.H. Jr. . Dept. of Biology)

    1994-07-01

    Sediments collected at various field locations may have chemical and physical constituents that influence test results and may contain organisms that cannot be readily removed. Thus, reference sediments are needed that can be formulated to match diverse freshwater and estuarine sediments encountered in comprehensive testing programs. This research evaluated formulated reference sediments in terms of (a) their ability to match field-collected sediments both chemically and physically; (b) their suitability as habitant (survival and reproduction) for typical invertebrate toxicity testing species (Hyalella azteca Saussure, Chironomus tentans Fabricius, and Daphnia magna Straus) during chronic exposures; and (c) their suitability as a substrate for Hyalella azteca, Chironomus tentans, Daphnia magna, Ceriodaphnia dubia Richard, and Pimephales promelas Rafinesque in 14-d whole-sediment exposures. Formulated reference sediments were prepared to match naturally occurring sediments with respect to particle-size distribution, organic matter, organic carbon, pH, solids, CEC, but not redox potential. After preparation, a conditioning period of at least 7 d was required for pH stabilization of formulated reference sediments. In culture experiments, formulated reference sediments was suitable for Hyalella azteca, Chironomus tentans, and Daphnia magna survival and reproduction for 56,40, and 28 d, respectively. Hyalella azteca, Chironomus tentans, Daphnia magna, Ceriodaphnia dubia and Pimephales promelas survival was [>=] 88% in 14-d exposures to formulated reference sediment. Formulated reference sediments may reduce some unexplained physical, chemical, or biological toxicity'' of field-collected sediments (e.g., organic matter) that may influence toxicity testing results.

  17. Do high concentrations of microcystin prevent Daphnia control of phytoplankton?

    PubMed

    Chislock, Michael F; Sarnelle, Orlando; Jernigan, Lauren M; Wilson, Alan E

    2013-04-15

    Toxin-producing cyanobacteria have frequently been hypothesized to limit the ability of herbivorous zooplankton (such as Daphnia) to control phytoplankton biomass by inhibiting feeding, and in extreme cases, causing zooplankton mortality. Using limnocorral experiments in hyper-eutrophic ponds located in Alabama and Michigan (U.S.A.), we tested the hypothesis that high levels of cyanobacteria and microcystin, a class of hepatotoxins produced by several cyanobacterial genera, prevent Daphnia from strongly reducing phytoplankton abundance. At the start of the first experiment (Michigan), phytoplankton communities were dominated by toxic Microcystis and Anabaena (∼96% of total phytoplankton biomass), and concentrations of microcystin were ∼3 μg L⁻¹. Two weeks after adding Daphnia pulicaria from a nearby eutrophic lake, microcystin levels increased to ∼6.5 μg L⁻¹, yet Daphnia populations increased exponentially (r = 0.24 day⁻¹). By the third week, Daphnia had suppressed phytoplankton biomass by ∼74% relative to the no Daphnia controls and maintained reduced phytoplankton biomass until the conclusion of the five-week experiment. In the second experiment (Alabama), microcystin concentrations were greater than 100 μg L⁻¹, yet a mixture of three D. pulicaria clones from eutrophic lakes in southern MI increased and again reduced phytoplankton biomass, in this case by over 80%. The ability of Daphnia to increase in abundance and suppress phytoplankton biomass, despite high initial levels of cyanobacteria and microcystin, indicates that the latter does not prevent strong control of phytoplankton biomass by Daphnia genotypes that are adapted to environments with abundant cyanobacteria and associated cyanotoxins.

  18. CRISPR/Cas-mediated targeted mutagenesis in Daphnia magna.

    PubMed

    Nakanishi, Takashi; Kato, Yasuhiko; Matsuura, Tomoaki; Watanabe, Hajime

    2014-01-01

    The water flea Daphnia magna has been used as an animal model in ecology, evolution, and environmental sciences. Thanks to the recent progress in Daphnia genomics, genetic information such as the draft genome sequence and expressed sequence tags (ESTs) is now available. To investigate the relationship between phenotypes and the available genetic information about Daphnia, some gene manipulation methods have been developed. However, a technique to induce targeted mutagenesis into Daphnia genome remains elusive. To overcome this problem, we focused on an emerging genome editing technique mediated by the clustered regularly interspaced short palindromic repeats/CRISPR-associated (CRISPR/Cas) system to introduce genomic mutations. In this study, we targeted a functionally conserved regulator of eye development, the eyeless gene in D. magna. When we injected Cas9 mRNAs and eyeless-targeting guide RNAs into eggs, 18-47% of the survived juveniles exhibited abnormal eye morphology. After maturation, up to 8.2% of the adults produced progenies with deformed eyes, which carried mutations in the eyeless loci. These results showed that CRISPR/Cas system could introduce heritable mutations into the endogenous eyeless gene in D. magna. This is the first report of a targeted gene knockout technique in Daphnia and will be useful in uncovering Daphnia gene functions.

  19. Pesticide toxicity index for freshwater aquatic organisms

    USGS Publications Warehouse

    Munn, Mark D.; Gilliom, Robert J.

    2001-01-01

    The U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program is designed to assess current water-quality conditions, changes in water quality over time, and the effects of natural and human factors on water quality for the Nation's streams and ground-water resources. For streams, one of the most difficult parts of the assessment is to link chemical conditions to effects on aquatic biota, particularly for pesticides, which tend to occur in streams as complex mixtures with strong seasonal patterns. A Pesticide Toxicity Index (PTI) was developed that combines pesticide exposure of aquatic biota (measured concentrations of pesticides in stream water) with toxicity estimates (standard endpoints from laboratory bioassays) to produce a single index value for a sample or site. The development of the PTI was limited to pesticide compounds routinely measured in NAWQA studies and to toxicity data readily available from existing databases. Qualifying toxicity data were found for one or more types of test organisms for 75 of the 83 pesticide compounds measured in NAWQA samples, but with a wide range of bioassays per compound (1 to 65). There were a total of 2,824 bioassays for the 75 compounds, including 287 48-hour EC50 values (concentration at which 50 percent of test organisms exhibit a nonlethal response) for freshwater cladocerans, 585 96-hour LC50 values (concentration lethal to 50 percent of test organisms) for freshwater benthic invertebrates, and 1,952 96-hour LC50 values for freshwater fish. The PTI for a particular sample is the sum of toxicity quotients (measured concentration divided by the median toxicity concentration from bioassays) for each detected pesticide. The PTI can be calculated for specific groups of pesticides and for specific taxonomic groups.While the PTI does not determine whether water in a sample is toxic, its values can be used to rank or compare the toxicity of samples or sites on a relative basis for use in further analysis or

  20. Population dynamics of the tropical cladoceran Ceriodaphnia rigaudi Richard, 1894 (Crustacea: Anomopoda). Effect of food type and temperature.

    PubMed

    Martinez-Jeronimo, Fernando; Ventura-Lopez, Claudia

    2011-07-01

    The knowledge of population effects of food on tropical, filter-feeding cladocerans is scarce because a reduced number of species has been extensively studied. Ceriodaphnia rigaudi Richard 1894, a small-sized cladoceran distributed mainly in tropical and subtropical regions of the world, was studied. The aim of this study was to contribute to the knowledge of the reproductive biology of a poor-known Cladoceran; for this we assessed the effect of feeding and temperature on the reproduction and life cycle of this species. Three microalga species (Pseudokirchneriella subcapitata, Ankistrodesmus falcatus, and Chlorella vulgaris) were supplied as food each at a concentration of 12 mg l(-1) (dry weight, equivalent to 1.3 x 10(6), 0.4 x 10(6) and 1.35 x 10(6) cell m1(-1), respectively, and equivalent to 7.8 microg C ml(-1), at two temperatures (20 and 25 degrees C). We evaluated, among other responses, longevity, total progeny, survival, life expectancy at birth and fecundity. Organisms fed with the microalgae A. falcatus and P subcapitata presented both higher longevity (30.7 +/- 5.91, 26.6 +/- 3.59 days, respectively) and total progeny (45 +/- 13.80, 40.7 +/- 0.66 neonates female (-1) values than those organisms fed C. vulgaris (13.5 +/- 4.63 days and 17.6 +/- 6.19 neonates female (-1), respectively). On the other hand, temperature affected significantly the population parameters of C. rigaudi, recording maximal longevity values (56.1 +/- 9.41 days) at 20 degrees C in organisms fed A. falcatus; however, age at first reproduction and total progeny were negatively affected by this temperature: sexual maturation of the females was delayed until the age of 16 days and the number of neonates produced was smaller (9.8 +/- 3.45 with C. vulgaris; 24.7 +/- 6.01 with P subcapitata, and 35.5 +/- 8.59 neonates female(-1) with A. falcatus). The best reproductive responses for C. rigaudi in this study were obtained with A. falcatus at degrees 25 degrees C.

  1. Gri freshwater str model and computer program: Overview, validation, and application. Topical report, April 1992-June 1994

    SciTech Connect

    Tietge, J.E.; Mount, D.R.; Gulley, D.D.

    1994-12-01

    The objective of this research was to develop a statistical relationship between concentrations of major ions and acute toxicity responses for three common freshwater organisms. These relationships, Freshwater Salinity Toxicity Relationships (FW STR), can be used to predict the acute toxicity of saline waters and aid in the management of regulated discharges from the gas industry. Laboratory toxicity tests using three common laboratory species (Ceriodaphnia dubia, Daphnia magna, and fathead minnows (Pimephales promelas)) were conducted on over 3,000 combinations of major ions (sodium, potassium, calcium, magnesium, chloride, sulfate, and bicarbonate).

  2. Influence of dissolved organic carbon on toxicity of copper to a unionid mussel (Villosa iris) and a cladoceran (Ceriodaphnia dubia) in acute and chronic water exposures

    USGS Publications Warehouse

    Wang, Ning; Mebane, Christopher A.; Kunz, James L.; Ingersoll, Christopher G.; Brumbaugh, William G.; Santore, Robert C.; Gorsuch, Joseph W.; Arnold, W. Ray

    2011-01-01

    Acute and chronic toxicity of copper (Cu) to a unionid mussel (Villosa iris) and a cladoceran (Ceriodaphnia dubia) were determined in water exposures at four concentrations of dissolved organic carbon (DOC; nominally 0.5, 2.5, 5, and 10 mg/L as carbon [C]). Test waters with DOC concentrations of 2.5 to 10 mg C/L were prepared by mixing a concentrate of natural organic matter (Suwannee River, GA, USA) in diluted well water (hardness 100 mg/L as CaCO3, pH 8.3, DOC 0.5 mg C/L). Acute median effect concentrations (EC50s) for dissolved Cu increased approximately fivefold (15–72 μg Cu/L) for mussel survival in 4-d exposures and increased about 11-fold (25–267 μg Cu/L) for cladoceran survival in 2-d exposures across DOC concentrations from 0.5 to 10 mg C/L. Similarly, chronic 20% effect concentrations (EC20s) for the mussel in 28-d exposures increased about fivefold (13–61 μg Cu/L for survival; 8.8–38 μg Cu/L for biomass), and the EC20s for the cladoceran in 7-d exposures increased approximately 17-fold (13–215 μg Cu/L) for survival or approximately fourfold (12–42 μg Cu/L) for reproduction across DOC concentrations from 0.5 to 10 mg C/L. The acute and chronic values for the mussel were less than or approximately equal to the values for the cladoceran. Predictions from the biotic ligand model (BLM) used to derive the U.S. Environmental Protection Agency's ambient water quality criteria (AWQC) for Cu explained more than 90% of the variation in the acute and chronic endpoints for the two species, with the exception of the EC20 for cladoceran reproduction (only 46% of variation explained). The BLM-normalized acute EC50s and chronic EC20s for the mussel and BLM-normalized chronic EC20s for the cladoceran in waters with DOC concentrations of 2.5 to 10 mg C/L were equal to or less than the final acute value and final chronic value in the BLM-based AWQC for Cu, respectively, indicating that the Cu AWQC might not adequately protect the mussel from acute and

  3. Influence of dissolved organic carbon on toxicity of copper to a unionid mussel (Villosa iris) and a cladoceran (Ceriodaphnia dubia) in acute and chronic water exposures.

    PubMed

    Wang, Ning; Mebane, Christopher A; Kunz, James L; Ingersoll, Christopher G; Brumbaugh, William G; Santore, Robert C; Gorsuch, Joseph W; Arnold, W Ray

    2011-09-01

    Acute and chronic toxicity of copper (Cu) to a unionid mussel (Villosa iris) and a cladoceran (Ceriodaphnia dubia) were determined in water exposures at four concentrations of dissolved organic carbon (DOC; nominally 0.5, 2.5, 5, and 10 mg/L as carbon [C]). Test waters with DOC concentrations of 2.5 to 10 mg C/L were prepared by mixing a concentrate of natural organic matter (Suwannee River, GA, USA) in diluted well water (hardness 100 mg/L as CaCO(3) , pH 8.3, DOC 0.5 mg C/L). Acute median effect concentrations (EC50s) for dissolved Cu increased approximately fivefold (15-72 µg Cu/L) for mussel survival in 4-d exposures and increased about 11-fold (25-267 µg Cu/L) for cladoceran survival in 2-d exposures across DOC concentrations from 0.5 to 10 mg C/L. Similarly, chronic 20% effect concentrations (EC20s) for the mussel in 28-d exposures increased about fivefold (13-61 µg Cu/L for survival; 8.8-38 µg Cu/L for biomass), and the EC20s for the cladoceran in 7-d exposures increased approximately 17-fold (13-215 µg Cu/L) for survival or approximately fourfold (12-42 µg Cu/L) for reproduction across DOC concentrations from 0.5 to 10 mg C/L. The acute and chronic values for the mussel were less than or approximately equal to the values for the cladoceran. Predictions from the biotic ligand model (BLM) used to derive the U.S. Environmental Protection Agency's ambient water quality criteria (AWQC) for Cu explained more than 90% of the variation in the acute and chronic endpoints for the two species, with the exception of the EC20 for cladoceran reproduction (only 46% of variation explained). The BLM-normalized acute EC50s and chronic EC20s for the mussel and BLM-normalized chronic EC20s for the cladoceran in waters with DOC concentrations of 2.5 to 10 mg C/L were equal to or less than the final acute value and final chronic value in the BLM-based AWQC for Cu, respectively, indicating that the Cu AWQC might not adequately protect the mussel from acute and

  4. Influence of dissolved organic carbon on toxicity of copper to a unionid mussel (Villosa iris) and a cladoceran (Ceriodaphnia dubia) in acute and chronic water exposures

    USGS Publications Warehouse

    Wang, N.; Mebane, C.A.; Kunz, J.L.; Ingersoll, C.G.; Brumbaugh, W.G.; Santore, R.C.; Gorsuch, J.W.; Arnold, W.R.

    2011-01-01

    Acute and chronic toxicity of copper (Cu) to a unionid mussel (Villosa iris) and a cladoceran (Ceriodaphnia dubia) were determined in water exposures at four concentrations of dissolved organic carbon (DOC; nominally 0.5, 2.5, 5, and 10mg/L as carbon [C]). Test waters with DOC concentrations of 2.5 to 10mgC/L were prepared by mixing a concentrate of natural organic matter (Suwannee River, GA, USA) in diluted well water (hardness 100mg/L as CaCO3, pH 8.3, DOC 0.5mgC/L). Acute median effect concentrations (EC50s) for dissolved Cu increased approximately fivefold (15-72??gCu/L) for mussel survival in 4-d exposures and increased about 11-fold (25-267??gCu/L) for cladoceran survival in 2-d exposures across DOC concentrations from 0.5 to 10mgC/L. Similarly, chronic 20% effect concentrations (EC20s) for the mussel in 28-d exposures increased about fivefold (13-61??gCu/L for survival; 8.8-38??gCu/L for biomass), and the EC20s for the cladoceran in 7-d exposures increased approximately 17-fold (13-215??gCu/L) for survival or approximately fourfold (12-42??gCu/L) for reproduction across DOC concentrations from 0.5 to 10mgC/L. The acute and chronic values for the mussel were less than or approximately equal to the values for the cladoceran. Predictions from the biotic ligand model (BLM) used to derive the U.S. Environmental Protection Agency's ambient water quality criteria (AWQC) for Cu explained more than 90% of the variation in the acute and chronic endpoints for the two species, with the exception of the EC20 for cladoceran reproduction (only 46% of variation explained). The BLM-normalized acute EC50s and chronic EC20s for the mussel and BLM-normalized chronic EC20s for the cladoceran in waters with DOC concentrations of 2.5 to 10mgC/L were equal to or less than the final acute value and final chronic value in the BLM-based AWQC for Cu, respectively, indicating that the Cu AWQC might not adequately protect the mussel from acute and chronic exposure, and the cladoceran

  5. Determination of bioactivity of chemical fractions of liquid wastes using freshwater and saltwater algae and crustaceans

    SciTech Connect

    Walsh, G.E.; Garnas, R.L.

    1983-03-01

    Complex wastes from industrial and municipal outfalls were fractionated chemically and tested for toxicity with freshwater and saltwater algae and crustaceans. The organic fraction of each waste was subfractionated into acid-, base-, and neutral-extractable portions, and the inorganic fraction was subfractionated into its anion and cation components. All wastes affected growth of the algae Skeletonema costatum (saltwater) and Monoraphidium capricornutum (freshwater) or survival of Mysidopsis bahia (saltwater) and Daphnia magna (freshwater). Usually, bioactivity was limited to one or two subfractions. In some cases, algal growth was stimulated by a fraction or subfraction, whereas stimulation was not detected in whole waste. It is suggested that fractionation must be done in order to estimate the full potential impact of complex wastes on aquatic systems. The method can also be used to identify toxic factors before application of cost-effective control technology.

  6. Development of a microinjection system for RNA interference in the water flea Daphnia pulex

    PubMed Central

    2013-01-01

    Background The ubiquitous, freshwater microcrustacean Daphnia pulex provides a model system for both human health research and monitoring ecosystem integrity. It is the first crustacean to have a well annotated, reference genome assembly that revealed an unusually high gene count highlighted by a large gene orphanage,-i.e., previously uncharacterized genes. Daphnia are capable of either clonal or sexual reproduction, making them ideally suited for genetic manipulation, but the establishment of gene manipulation techniques is needed to accurately define gene functions. Although previous investigations developed an RNA interference (RNAi) system for one congener D. magna, these methods are not appropriate for D. pulex because of the smaller size of their early embryos. In these studies, we develop RNAi techniques for D. pulex by first determining the optimum culture conditions of their isolated embryos and then applying these conditions to the development of microinjection techniques and proof-of-principle RNAi experiments. Results We found that isolated embryos were best cultured on a 2% agar plate bathed in 60 mM sucrose dissolved in M4 media, providing optimal conditions for microinjections. Then, we injected double-stranded (ds)RNA specific to the Distal-less gene (Dll), which is a homeobox transcription factor essential for limb development in invertebrates and vertebrates. Injected embryos presented with defects in the second antenna and appendage development, and dsRNA induced the degradation of Dll mRNAs, indicating that this technique successfully inhibited transcription of the target gene. Conclusions We developed a microinjection system for RNAi studies in D. pulex. These techniques add to the growing genomic toolbox and enhance the genetic tractability of this important model for environmental, evolutionary, and developmental genomics. PMID:24188141

  7. Evaluation of Daphnia Magna Neonate Viability under Low Temperature Exposure Conditions

    DTIC Science & Technology

    2007-01-25

    code) Evaluation of Daphnia magna Neonate Viability under Low Temperature Exposure Conditions Prepared For: United States Army...LIST OF ATTACHMENTS ATTACHMENT I DAPHNIA MAGNA 21-DAY REPRODUCTION TEST DATA – FIRST SERIES (JULY 28, 2006 - AUGUST 18, 2006...I ATTACHMENT II DAPHNIA MAGNA 21-DAY REPRODUCTION TEST DATA – SECOND SERIES (SEPTEMBER 19, 2006 - OCTOBER 21, 2006) ....II

  8. Cloning, expression and localization of the Daphnia carinata transformer gene DcarTra during different reproductive stages.

    PubMed

    Kong, Ling; Lv, Weiwei; Huang, Youhui; Liu, Zhiquan; Yang, Yang; Zhao, Yunlong

    2015-07-25

    In this study, the full-length cDNA of the Transformer (Tra) gene from the common freshwater species Daphnia carinata (DcarTra; GenBank accession no. KJ735445) was cloned using primers based on homologous sequences and rapid amplification of cDNA ends (RACE). The relative expression and localization of DcarTra and the cellular abundance of the DcarTra protein during different sexual phases were subsequently investigated. The full-length DcarTra cDNA was 1620 bp with an ORF of 1143 bp encoding a 380 amino acid polypeptide. Phylogenetic analysis identified closely related genes in Daphnia magna and Daphnia pulex, and more distantly related genes in other insects. Quantitative PCR showed that DcarTra expression was highest in males, followed by sexual females, and lowest in parthenogenetic females. Whole-mount in situ hybridization showed that DcarTra was mainly expressed in the thoracic limbs, ovaries and rectum in parthenogenetic females, and in the joints of second antennae, ovaries, rectum and ventral processes in sexual females. Western blotting showed two differently phosphorylated forms of the Tra protein. When Tra is phosphorylated, DcarTra protein levels were much higher in males than in two females. Otherwise, when Tra is dephosphorylated, the highest Tra protein levels were in sexual females, which revealed that D. carinata can control the sexual transition via these two forms. Together these results suggest that DcarTra plays significant roles in the reproductive transformation of D. carinata and dephosphorylation of DcarTra may be the trigger for females to transform into males.

  9. Submerged Macrophytes Mitigate Direct and Indirect Insecticide Effects in Freshwater Communities

    PubMed Central

    Brogan, William R.; Relyea, Rick A.

    2015-01-01

    Understanding how ecological interactions mitigate the impacts of perturbations such as pesticides in biological communities is an important basic and applied question for ecologists. In aquatic ecosystems, new evidence from microcosm experiments suggests that submerged macrophytes can buffer cladocerans from pulse exposures to the widely used insecticide malathion, and that mitigation increases with macrophyte density. However, whether these results scale up to more complex aquatic communities where ecological interactions such as competition can alter toxicity is unknown. Further, macrophyte abilities to mitigate different insecticide exposure scenarios (i.e. single versus repeated pulses) have never been tested. To address these gaps, we performed a factorial mesocosm experiment examining the influence of four macrophyte treatments (0, 10, 50, or 100 Elodea Canadensis shoots planted per mesocosm) crossed with three malathion exposure scenarios (no insecticide, single pulse, repeated pulses) on aquatic communities containing zooplankton, phytoplankton, periphyton, two snail species, and larval amphibians. In the absence of macrophytes, single malathion pulses caused short-term declines in cladoceran abundance followed by their rapid recovery, which precluded any indirect effects (i.e. trophic cascades). However, repeated malathion pulses caused cladoceran extinctions, resulting in persistent phytoplankton blooms and reduced abundance of one snail species. In contrast, with macrophytes present, even at low density, malathion had no effect on any taxa. We also discovered novel effects of macrophytes on the benthic food web. In the two highest macrophyte treatments, we observed trends of reduced periphyton biomass, decreased abundance of one snail species, and decreased amphibian time to and mass at metamorphosis. To our knowledge, this is the first evidence of negative submerged macrophyte effects on amphibians, a taxa of global conservation concern. Our findings

  10. Genetic determination of tolerance to lethal and sublethal copper concentrations in field populations of Daphnia longispina.

    PubMed

    Lopes, I; Baird, D J; Ribeiro, R

    2004-01-01

    In order to study the effects of environmental pollution on the genetic diversity of natural populations, two field populations of the cladoceran Daphnia longispina were sampled: one in a reference site (uncontaminated) and the other in a site historically stressed with acid mine drainage (AMD). Five hypotheses were formulated: (1) the stressed population presents a higher tolerance to lethal levels of copper than the reference population, (2) differences in tolerance to lethal levels, observed between the two populations, are due to the loss of sensitive lineages, (3) differences in tolerance to lethal levels of copper between the two populations are due to the appearance of new genotypes, (4) the acquisition of tolerance to lethal levels of copper involved changes in life-history patterns and fitness costs under optimal conditions, and (5) historical contamination by AMD resulted in tolerance differences to sublethal levels between populations, within categories similarly tolerant to lethality, specifically, lineages with similar tolerance to lethal levels from both populations show differences in tolerance to sublethal levels, the stressed population being more tolerant to sublethal levels of contamination than the reference population. Over 125 acclimated cloned lineages, from each population, were exposed to different copper concentrations for 24 hours. At the end of each assay, mortality and feeding inhibition were monitored. Life-cycle traits under optimal conditions were also monitored (time to first brood, number of neonates per brood, inter-brood time, body length, and ingested algae). At lethal levels of copper, significant differences were found in the frequency of sensitive lineages between the two populations. The stressed population did not include the most sensitive lineages, though the most tolerant ones were also present in the reference population. Thus, the hypothesis of presence of new genotypes in the stressed population resulting in an

  11. The ABC transporter gene family of Daphnia pulex

    PubMed Central

    Sturm, Armin; Cunningham, Phil; Dean, Michael

    2009-01-01

    Background The large gene superfamily of ABC (ATP-binding cassette) transporters encodes membrane proteins involved in trafficking processes across biological membranes and further essential cell biological functions. ABC transporters are evolutionary ancient and involved in the biochemical defence against toxicants. We report here a genome-wide survey of ABC proteins of Daphnia pulex, providing for the first time information on ABC proteins in crustacea, a primarily aquatic arthropod subphylum of high ecological and economical importance. Results We identified 64 ABC proteins in the Daphnia genome, which possesses members of all current ABC subfamilies A to H. To unravel phylogenetic relationships, ABC proteins of Daphnia were compared to those from yeast, worm, fruit fly and human. A high conservation of Daphnia of ABC transporters was observed for proteins involved in fundamental cellular processes, including the mitochondrial half transporters of the ABCB subfamily, which function in iron metabolism and transport of Fe/S protein precursors, and the members of subfamilies ABCD, ABCE and ABCF, which have roles in very long chain fatty acid transport, initiation of gene transcription and protein translation, respectively. A number of Daphnia proteins showed one-to-one orthologous relationships to Drosophila ABC proteins including the sulfonyl urea receptor (SUR), the ecdysone transporter ET23, and the eye pigment precursor transporter scarlet. As the fruit fly, Daphnia lacked homologues to the TAP protein, which plays a role in antigene processing, and the cystic fibrosis transmembrane conductance regulator (CFTR), which functions as a chloride channel. Daphnia showed two proteins homologous to MDR (multidrug resistance) P-glycoproteins (ABCB subfamily) and six proteins homologous to MRPs (multidrug resistance-associated proteins) (ABCC subfamily). However, lineage specific gene duplications in the ABCB and ABCC subfamilies complicated the inference of function. A

  12. Gene transcription, metabolite and lipid profiling in eco-indicator daphnia magna indicate diverse mechanisms of toxicity by legacy and emerging flame-retardants.

    PubMed

    Scanlan, Leona D; Loguinov, Alexandre V; Teng, Quincy; Antczak, Philipp; Dailey, Kathleen P; Nowinski, Daniel T; Kornbluh, Jonah; Lin, Xin Xin; Lachenauer, Erica; Arai, Audrey; Douglas, Nora K; Falciani, Francesco; Stapleton, Heather M; Vulpe, Chris D

    2015-06-16

    The use of chemical flame-retardants (FR) in consumer products has steadily increased over the last 30 years. Toxicity data exist for legacy FRs such as pentabromodiphenyl ether (pentaBDE), but less is known about effects of new formulations. To address this issue, the toxicity of seven FR chemicals and formulations was assessed on the freshwater crustacean Daphnia magna. Acute 48-h nominal LC50 values for penta- and octabromodiphenyl ether (pentaBDE, octaBDE), Firemaster 550 (FM550), Firemaster BZ-54 (BZ54), bis(2-ethylhexyl) tetrabromophthalate (BEH-TEBP), triphenyl phosphate (TPhP), and nonbrominated BEH-TEBP analog bis(2-ethylhexyl) phthalate (BEHP) ranged from 0.058 mg/L (pentaBDE) to 3.96 mg/L (octaBDE). mRNA expression, (1)H NMR-based metabolomic and lipidomic profiling at 1/10 LC50 revealed distinct patterns of molecular response for each exposure, suggesting pentaPBDE affects transcription and translation, octaBDE and BEH-TEBP affect glycosphingolipid biosynthesis and BZ54 affects Wnt and Hedgehog signal pathways as well as glycosaminoglycan degradation. Brominated components of FM550 (i.e., BZ54) were significantly higher in Daphnia after 48 h following 1/10 LC50 exposure. FM550 elicited significant mRNA changes at five concentrations across a range from 1/10(6) LC50 to 1/2 LC50. Analyses suggest FM550 impairs nutrient utilization or uptake in Daphnia.

  13. Stable isotope composition in Daphnia is modulated by growth, temperature, and toxic exposure: implications for trophic magnification factor assessment.

    PubMed

    Ek, Caroline; Karlson, Agnes M L; Hansson, Sture; Garbaras, Andrius; Gorokhova, Elena

    2015-06-02

    The potential for using stable isotope analysis in risk assessment of environmental contaminants is crucially dependent on the predictability of the trophic transfer of isotopes in food webs. The relationship between contaminant levels and trophic position of consumers is widely used to assess biomagnification properties of various pollutants by establishing trophic magnification factors (TMF). However, contaminant-induced variability of the isotopic composition in biota is poorly understood. Here, we investigated effects of toxic exposure on δ(15)N and δ(13)C values in a consumer, with a main hypothesis that these effects would be largely mediated via growth rate and metabolic turnover of the test animals. The cladoceran Daphnia magna was used in two experiments that were conducted to manipulate growth and body condition (assayed as C:N ratio) by food availability and temperature (Experiment 1) and by toxic exposure to the pesticide lindane (Experiment 2). We found a significant negative effect of growth rate and a positive effect of temperature on the consumer-diet discrimination factor for δ(15)N and δ(13)C, with no effects on the C:N ratio (Experiment 1). In lindane-exposed daphnids, a significant growth inhibition was observed, with concomitant increase in metabolic costs and significantly elevated size-specific δ(15)N and δ(13)C values. Moreover, a significantly higher incorporation of carbon relative to nitrogen, yet a concomitant decrease in C:N ratio was observed in the exposed animals. Together, these results have methodological implications for determining trophic positions and TMF in polluted environments, where elevated δ(15)N values would translate into overestimated trophic positions and underestimated TMF. Furthermore, altered δ(13)C values may lead to erroneous food-chain assignment of the consumer in question.

  14. Uncovering ultrastructural defences in Daphnia magna--an interdisciplinary approach to assess the predator-induced fortification of the carapace.

    PubMed

    Rabus, Max; Söllradl, Thomas; Clausen-Schaumann, Hauke; Laforsch, Christian

    2013-01-01

    The development of structural defences, such as the fortification of shells or exoskeletons, is a widespread strategy to reduce predator attack efficiency. In unpredictable environments these defences may be more pronounced in the presence of a predator. The cladoceran Daphnia magna (Crustacea: Branchiopoda: Cladocera) has been shown to develop a bulky morphotype as an effective inducible morphological defence against the predatory tadpole shrimp Triops cancriformis (Crustacea: Branchiopoda: Notostraca). Mediated by kairomones, the daphnids express an increased body length, width and an elongated tail spine. Here we examined whether these large scale morphological defences are accompanied by additional ultrastructural defences, i.e. a fortification of the exoskeleton. We employed atomic force microscopy (AFM) based nanoindentation experiments to assess the cuticle hardness along with tapping mode AFM imaging to visualise the surface morphology for predator exposed and non-predator exposed daphnids. We used semi-thin sections of the carapace to measure the cuticle thickness, and finally, we used fluorescence microscopy to analyse the diameter of the pillars connecting the two carapace layers. We found that D. magna indeed expresses ultrastructural defences against Triops predation. The cuticle in predator exposed individuals is approximately five times harder and two times thicker than in control daphnids. Moreover, the pillar diameter is significantly increased in predator exposed daphnids. These predator-cue induced changes in the carapace architecture should provide effective protection against being crushed by the predator's mouthparts and may add to the protective effect of bulkiness. This study highlights the potential of interdisciplinary studies to uncover new and relevant aspects even in extensively studied fields of research.

  15. The Time- and Age-dependent Effects of the Juvenile Hormone Analog Pesticide, Pyriproxyfen on Daphnia magna Reproduction

    PubMed Central

    Ginjupalli, Gautam K.; Baldwin, William S.

    2013-01-01

    Pyriproxyfen is an insecticidal juvenile hormone analog that perturbs insect and tick development. Pyriproxyfen also alters parthenogenic reproduction in non-target cladoceran species as it induces male production that can lead to a decrease in fecundity, a reduction in population density, and subsequent ecological effects. In this study, we investigate the impacts of pyriproxyfen on Daphnia magna reproduction using a series of male production screening assays. These assays demonstrate that pyriproxyfen increases male production in a concentration-dependent fashion with an EC50 of 156 pM (50.24 ng L-1); a concentration considered environmentally relevant. Furthermore, pyriproxyfen decreases overall fecundity at all ages tested (7, 14, 21-d old female parthenogenic daphnids). Juvenile (3-d old) and reproductively mature (10-d old) female daphnids were also exposed to 155 pM pyriproxyfen for 2 – 12 d and reproduction measured for 16 d to compare the effects of short-term and prolonged exposures, and determine the potential for recovery. Results indicate that longer pyriproxyfen exposures (8–12 d) extend male production and decrease reproduction; however, daphnids exposed for only 2–4 d recover and produce a relatively normal abundance of neonates. In addition, juvenile daphnids are also very sensitive to pyriproxyfen, but the primary effect on juvenile daphnids is reduced reproduction and protracted development not male production. Taken together, continued use of pyriproxyfen around water bodies needs due caution because of its potential adverse effects with significant developmental delays and male production compounded by prolonged exposure. PMID:23714148

  16. Single and combined toxicity of pharmaceuticals at environmentally relevant concentrations in Daphnia magna--a multigenerational study.

    PubMed

    Dietrich, Sabine; Ploessl, Florian; Bracher, Franz; Laforsch, Christian

    2010-03-01

    Pharmaceuticals are continuously discharged into the environment, resulting in the chronic exposure of aquatic organisms to these compounds. In this multigenerational study, we examined the influence of four pharmaceuticals (carbamazepine (CBZ), diclofenac (DIC), 17alpha-ethinylestradiol (EE2) and metoprolol (MET)) as single substances and as a drug mixture at environmentally relevant concentrations on life-history and morphological parameters over six generations of the cladoceran Daphnia magna. Detectable effects of the used pharmaceuticals occured in the first observed generation, followed by an acclimation period and a recurrence of drug effects in later generations: daphnids exposed to MET were affected by the pharmaceutical, resulting in a decreased body length at first reproduction in the generations F0, F3 and F4 and in a reduced number of offspring in the generations F0 and F4. Similar effects were observed in daphnids exposed to EE2. DIC delayed age at first reproduction in the F0 and F2 generations and increased the body length of neonates in the generations F1 and F5. Daphnids exposed to CBZ showed a delay in the age at first reproduction for the F0 generation only. The drug mixture reduced the age at first reproduction of daphnids in the F0 and F2 generation and increased the body length at first reproduction in the generations F0 and F3. Neither the single drugs nor the pharmaceutical mixture influenced the successive generations of D. magna in a steady way. Thus, multigenerational studies are necessary to prevent insufficient assessments on the impact of pharmaceuticals in aquatic ecosystems.

  17. The time- and age-dependent effects of the juvenile hormone analog pesticide, pyriproxyfen on Daphnia magna reproduction.

    PubMed

    Ginjupalli, Gautam K; Baldwin, William S

    2013-08-01

    Pyriproxyfen is an insecticidal juvenile hormone analog that perturbs insect and tick development. Pyriproxyfen also alters parthenogenic reproduction in non-target cladoceran species as it induces male production that can lead to a decrease in fecundity, a reduction in population density, and subsequent ecological effects. In this study, we investigate the impacts of pyriproxyfen on Daphnia magna reproduction using a series of male production screening assays. These assays demonstrate that pyriproxyfen increases male production in a concentration-dependent fashion with an EC50 of 156pM (50.24ngL(-1)); a concentration considered environmentally relevant. Furthermore, pyriproxyfen decreases overall fecundity at all ages tested (7, 14, 21-d old female parthenogenic daphnids). Juvenile (3-d old) and reproductively mature (10-d old) female daphnids were also exposed to 155pM pyriproxyfen for 2-12d and reproduction measured for 16d to compare the effects of short-term and prolonged exposures, and determine the potential for recovery. Results indicate that longer pyriproxyfen exposures (8-12d) extend male production and decrease reproduction; however, daphnids exposed for only 2-4d recover and produce a relatively normal abundance of neonates. In addition, juvenile daphnids are also very sensitive to pyriproxyfen, but the primary effect on juvenile daphnids is reduced reproduction and protracted development not male production. Taken together, continued use of pyriproxyfen around water bodies needs due caution because of its potential adverse effects with significant developmental delays and male production compounded by prolonged exposure.

  18. [Acute Toxicity of Coptis chinensis Rhizome Extracts to Daphnia carinata].

    PubMed

    Chen, Ya-nan; Yuan, Ling

    2015-10-01

    Coptis chinensis rhizome and preparations were widely used for the treatment of fish diseases in aquaculture. the acute toxicological effect of CRE on lethal, movement and phototaxis was studied on Daphnia carinata monoclone as a test animal in the present experiment. The results showed that CRE was acute toxic to this animal and alkaloids berberine concentrations in CRE changed in the following sequence: half lethal > half inhibitory > limitable, which led to a significant change in phototaxis index of Daphnia carinata. The concentration of CRE for the significant change in phototaxis index was 4.27 mg x L(-1), which was lower than the concentration in water to cure the fish diseases and this conclusion indicated an ecological risk of this antibiotic to Daphnia carinata in aquaculture. In addition, the concentration of CRE in phototaxis index was changed from 30.62 times at 48th hour to 36.51 times at 24th hour that were lower than half lethal concentration. Detecting phototaxis index was easy and only 3 hours was required, so utilizing the quickly change of Daphnia carinata phototaxis can be an effective method to monitor the toxicity effect of CRE on Daphnia carinata. The abuse of rhizome or preparations in aquaculture might destroy the aquatic food chain, resulting in an imbalance of aquatic ecosystems.

  19. Temperature and kairomone induced life history plasticity in coexisting Daphnia

    USGS Publications Warehouse

    Bernot, R.J.; Dodds, W.K.; Quist, M.C.; Guy, C.S.

    2006-01-01

    We investigated the life history alterations of coexisting Daphnia species responding to environmental temperature and predator cues. In a laboratory experiment, we measured Daphnia life history plasticity under different predation risk and temperature treatments that simulate changing environmental conditions. Daphnia pulicaria abundance and size at first reproduction (SFR) declined, while ephippia (resting egg) formation increased at high temperatures. Daphnia mendotae abundance and clutch size increased with predation risk at high temperatures, but produced few ephippia. Thus, each species exhibited phenotypic plasticity, but responded in sharply different ways to the same environmental cues. In Glen Elder reservoir, Kansas USA, D. pulicaria dominance shifted to D. mendotae dominance as temperature and predation risk increased from March to June in both 1999 and 2000. Field estimates of life history shifts mirrored the laboratory experiment results, suggesting that similar phenotypic responses to seasonal cues contribute to seasonal Daphnia population trends. These results illustrate species-specific differences in life history plasticity among coexisting zooplankton taxa. ?? Springer-Verlag 2006.

  20. Sucralose Induces Biochemical Responses in Daphnia magna

    PubMed Central

    Eriksson Wiklund, Ann-Kristin; Adolfsson-Erici, Margaretha; Liewenborg, Birgitta; Gorokhova, Elena

    2014-01-01

    The intense artificial sweetener sucralose has no bioconcentration properties, and no adverse acute toxic effects have been observed in standard ecotoxicity tests, suggesting negligible environmental risk. However, significant feeding and behavioural alterations have been reported in non-standard tests using aquatic crustaceans, indicating possible sublethal effects. We hypothesized that these effects are related to alterations in acetylcholinesterase (AChE) and oxidative status in the exposed animals and investigated changes in AChE and oxidative biomarkers (oxygen radical absorbing capacity, ORAC, and lipid peroxidation, TBARS) in the crustacean Daphnia magna exposed to sucralose (0.0001–5 mg L−1). The sucralose concentration was a significant positive predictor for ORAC, TBARS and AChE in the daphnids. Moreover, the AChE response was linked to both oxidative biomarkers, with positive and negative relationships for TBARS and ORAC, respectively. These joint responses support our hypothesis and suggest that exposure to sucralose may induce neurological and oxidative mechanisms with potentially important consequences for animal behaviour and physiology. PMID:24699280

  1. The response of European Daphnia magna Straus and Australian Daphnia carinata King to changes in geomagnetic field.

    PubMed

    Krylov, Viacheslav V; Bolotovskaya, Irina V; Osipova, Elena A

    2013-03-01

    This study investigates the effects of lifelong exposure to reversed geomagnetic and zero geomagnetic fields (the latter means absence of geomagnetic field) on the life history of Daphnia carinata King from Australia and Daphnia magna Straus from Europe. Considerable deviation in the geomagnetic field from the usual strength, leads to a decrease in daphnia size and life span. Reduced brood sizes and increased body length of neonates are observed in D. magna exposed to unusual magnetic background. The most apparent effects are induced by zero geomagnetic field in both species of Daphnia. A delay in the first reproduction in zero geomagnetic field is observed only in D. magna. No adaptive maternal effects to reversed geomagnetic field are found in a line of D. magna maintained in these magnetic conditions for eight generations. Integrally, the responses of D. magna to unusual geomagnetic conditions are more extensive than that in D. carinata. We suggest that the mechanism of the effects of geomagnetic field reversal on Daphnia may be related to differences in the pattern of distribution of the particles that have a magnetic moment, or to moving charged organic molecules owing to a change in combined outcome and orientation of the geomagnetic field and Earth's gravitational field. The possibility of modulation of self-oscillating processes with changes in geomagnetic field is also discussed.

  2. Chronic toxicity of erythromycin thiocyanate to Daphnia magna in a flow-through, continuous exposure test system

    USGS Publications Warehouse

    Meinertz, J.R.; Schreier, T.M.; Bernardy, J.A.

    2011-01-01

    Approval of a new animal drug application for AQUAMYCIN 100?? (erythromycin thiocyanate; ET) to treat freshwater salmonid species with bacterial kidney disease is being pursued in the US. As part of the approval process, ETs impact on an aquatic environment had to be described in an environmental assessment. The environmental assessment was lacking data to characterize the effect ET would have on a chronically exposed aquatic invertebrate organism. A major step to fulfilling the environmental assessment was completed after conducting a comprehensive study continuously exposing Daphnia magna to ET for 21 days. Results indicated that the no observable effect concentration for ET was 179 ??g/L. ?? 2011 Springer Science+Business Media, LLC (outside the USA).

  3. The good, the bad and the plenty: interactive effects of food quality and quantity on the growth of different Daphnia species.

    PubMed

    Bukovinszky, Tibor; Verschoor, Antonie M; Helmsing, Nico R; Bezemer, T Martijn; Bakker, Elisabeth S; Vos, Matthijs; de Senerpont Domis, Lisette N

    2012-01-01

    Effects of food quality and quantity on consumers are neither independent nor interchangeable. Although consumer growth and reproduction show strong variation in relation to both food quality and quantity, the effects of food quality or food quantity have usually been studied in isolation. In two experiments, we studied the growth and reproduction in three filter-feeding freshwater zooplankton species, i.e. Daphnia galeata x hyalina, D. pulicaria and D. magna, on their algal food (Scenedesmus obliquus), varying in carbon to phosphorus (C∶P) ratios and quantities (concentrations). In the first experiment, we found a strong positive effect of the phosphorus content of food on growth of Daphnia, both in their early and late juvenile development. Variation in the relationship between the P-content of animals and their growth rate reflected interspecific differences in nutrient requirements. Although growth rates typically decreased as development neared maturation, this did not affect these species-specific couplings between growth rate and Daphnia P-content. In the second experiment, we examined the effects of food quality on Daphnia growth at different levels of food quantity. With the same decrease in P-content of food, species with higher estimated P-content at zero growth showed a larger increase in threshold food concentrations (i.e. food concentration sufficient to meet metabolic requirements but not growth). These results suggest that physiological processes such as maintenance and growth may in combination explain effects of food quality and quantity on consumers. Our study shows that differences in response to variation in food quality and quantity exist between species. As a consequence, species-specific effects of food quality on consumer growth will also determine how species deal with varying food levels, which has implications for resource-consumer interactions.

  4. Terrestrial carbohydrates support freshwater zooplankton during phytoplankton deficiency

    PubMed Central

    Taipale, Sami J.; Galloway, Aaron W. E.; Aalto, Sanni L.; Kahilainen, Kimmo K.; Strandberg, Ursula; Kankaala, Paula

    2016-01-01

    Freshwater food webs can be partly supported by terrestrial primary production, often deriving from plant litter of surrounding catchment vegetation. Although consisting mainly of poorly bioavailable lignin, with low protein and lipid content, the carbohydrates from fallen tree leaves and shoreline vegetation may be utilized by aquatic consumers. Here we show that during phytoplankton deficiency, zooplankton (Daphnia magna) can benefit from terrestrial particulate organic matter by using terrestrial-origin carbohydrates for energy and sparing essential fatty acids and amino acids for somatic growth and reproduction. Assimilated terrestrial-origin fatty acids from shoreline reed particles exceeded available diet, indicating that Daphnia may convert a part of their dietary carbohydrates to saturated fatty acids. This conversion was not observed with birch leaf diets, which had lower carbohydrate content. Subsequent analysis of 21 boreal and subarctic lakes showed that diet of herbivorous zooplankton is mainly based on high-quality phytoplankton rich in essential polyunsaturated fatty acids. The proportion of low-quality diets (bacteria and terrestrial particulate organic matter) was <28% of the assimilated carbon. Taken collectively, the incorporation of terrestrial carbon into zooplankton was not directly related to the concentration of terrestrial organic matter in experiments or lakes, but rather to the low availability of phytoplankton. PMID:27510848

  5. Toxicity of six heterocyclic nitrogen compounds to Daphnia pulex

    SciTech Connect

    Perry, C.M.; Smith, S.B.

    1988-10-01

    The authors determined the relative toxicities to the aquatic crustacean Daphnia pulex of the six heterocyclic nitrogen compounds: 3-(1-methyl-2-pyrrolidinyl)pyridine (nicotine), 2-pyrrolidinone, 1-methylpyrrolidine, 2-(2-hydroxyethyl)pyridine, 2-amino-4,6-dimethylpyridine, and 2-amino-4,7(1H,8H)-pteridinedione(isoxanthopterin). These compounds were selected because they were detected in lake trout or walleyes and were commercially available. Daphnia pulex was used as the test organism because it is endemic to the Great Lakes, is easy to culture, has parthenogenic reproduction, constant genetic makeup over generations, and is sensitive to ecological stress.

  6. The acute toxicity of thallium to freshwater organisms: Implications for risk assessment.

    PubMed

    Tatsi, Kristi; Turner, Andrew; Handy, Richard D; Shaw, Benjamin J

    2015-12-01

    The acute toxicity of Tl(I) to the microalga, Pseudokirchneriella subcapitata, the planktonic crustaceans, Daphnia magna and Daphnia pulex, and early-life stage of the zebrafish, Danio rerio, has been studied according to OECD protocols. Toxicological end-point concentrations for the microalga ranged from 17 μg l(-1) for a 72 h EyC25 (yield inhibition) to 80 μg l(-1) for a 72 h ErC50 (growth inhibition). Daphnia were less sensitive to Tl, with 48 h EC50s of about 1000 μg l(-1) and 1200 μg l(-1) for D. magna and D. pulex, respectively; however, end-point concentrations were reduced considerably (to about 510 μg l(-1) and 730 μg l(-1), respectively) when experiments were repeated in dechlorinated Plymouth tap water (rather than OECD medium). The 96 h LC50 for D. rerio was 870 μg l(-1) but a variety of sub-lethal effects, including enlargement of yolk sac and reduction in heart beat rate, were observed when larvae were exposed to lower concentrations. Based on these results, a predicted no effect concentration (PNEC) for Tl in freshwaters of 0.087 μg l(-1) is proposed. The PNEC is an order of magnitude lower than the only (Canadian) water quality guideline for Tl that appears to exist, and is lower than Tl concentrations reported in freshwaters impacted by historical or contemporary metal mining. Our results are also consistent with previous studies that employ different organisms and end-points in that Tl toxicity is dependent on the concentration of K+, the biogeochemical analogue of Tl+. Accordingly, regulation of Tl in the freshwater environment should factor in the relative abundance of K.

  7. Linear solvation energy relationships for toxicity of selected organic chemicals to Daphnia pulex and Daphnia magna

    USGS Publications Warehouse

    Passino, Dora R.M.; Hickey, James P.; Frank, Anthony M.

    1988-01-01

    In the Laurentian Great Lakes, more than 300 contaminants have been identified in fish, other biota, water, and sediment. Current hazard assessment of these chemicals by the National Fisheries Research Center-Great Lakes is based on their toxicity, occurrence in the environment, and source. Although scientists at the Center have tested over 70 chemicals with the crustacean Daphnia pulex, the number of experimental data needed to screen the huge array of chemicals in the Great Lakes exceeds the practical capabilities of conducting bioassays. This limitation can be partly circumvented, however, by using mathematical models based on quantitative structure-activity relationships (QSAR) to provide rapid, inexpensive estimates of toxicity. Many properties of chemicals, including toxicity, bioaccumulation and water solubility are well correlated and can be predicted by equations of the generalized linear solvation energy relationships (LSER). The equation we used to model solute toxicity is Toxicity = constant + mVI/100 + s (π* + dδ) + bβm + aαm where VI = intrinsic (Van der Waals) molar volume; π* = molecular dipolarity/polarizability; δ = polarizability 'correction term'; βm = solute hydrogen bond acceptor basicity; and αm = solute hydrogen bond donor acidity. The subscript m designates solute monomer values for α and β. We applied the LSER model to 48-h acute toxicity data (measured as immobilization) for six classes of chemicals detected in Great Lakes fish. The following regression was obtained for Daphnia pulex (concentration = μM): log EC50 = 4.86 - 4.35 VI/100; N = 38, r2 = 0.867, sd = 0.403 We also used the LSER modeling approach to analyze to a large published data set of 24-h acute toxicity for Daphnia magna; the following regression resulted, for eight classes of compounds (concentration = mM): log EC50 = 3.88 - 4.52 VI/100 - 1.62 π* + 1.66 βm - 0.916 αm; N = 62, r2 = 0.859, sd = 0.375 In addition we developed computer software that identifies

  8. Freshwater mussels of Florida

    USGS Publications Warehouse

    Williams, James D.; Butler, Robert S.; Warren, Gary L.; Johnson, Nathan A.

    2014-01-01

    An exhaustive guide to all aspects of the freshwater mussel fauna in Florida,Freshwater Mussels of Florida covers the ecology, biology, distribution, and conservation of the many species of bivalve mollusks in the Sunshine State. In the past three decades, researchers, the public, businesses that depend on wildlife, and policy makers have given more attention to the threatened natural diversity of the Southeast, including freshwater mussels. This compendium meets the increasingly urgent need to catalog this imperiled group of aquatic organisms in the United States.

  9. Freshwater in situ toxicity testing: Daphnia magna, Ceriodaphnia dubia, Pimephales promelas, Hyalella azteca and Chironomus tentans

    SciTech Connect

    Burton, G.A. Jr.

    1995-12-31

    The use of traditional laboratory toxicity test species in field exposures have proven to be a valuable assessment tool for monitoring effluent, water, sediment and storm water quality. Mimicking fluctuating exposures of stressors with associated interactions with differing physico-chemical variables is difficult. In situ exposures are conducted for similar time periods measuring similar response endpoints as in more traditional laboratory tests. However, organisms are transferred to the field and exposed in various types of test chambers. The author has observed responses which are similar and which are significantly different from simultaneous laboratory exposures. Temperature, dissolved oxygen, suspended solids, natural light, flow, and predation may affect in situ responses, but are often removed from laboratory exposures. The strengths and weaknesses observed with these test systems over the past few years will be reviewed.

  10. Multigenerational effects of carbendazim in Daphnia magna.

    PubMed

    Silva, Ana Rita R; Cardoso, Diogo N; Cruz, Andreia; Pestana, João L T; Mendo, Sónia; Soares, Amadeu M V M; Loureiro, Susana

    2017-02-01

    Carbendazim is a fungicide largely used in agriculture as a plant protection product. As a result of agricultural runoffs, drainage, and leaching, it reaches surface waters at concentrations possibly hazardous to aquatic communities. Because of potential and continuous release of carbendazim to aquatic systems, long-term exposure to aquatic organisms should be addressed. To fill the knowledge gap, the present study evaluated the responses of multiple generations of Daphnia magna (clone K6) to an environmentally relevant concentration of carbendazim (5 μg/L). Twelve successive generations were evaluated, and the effects in these offspring were compared with those from a control population. Neonates' fitness was assessed through immobilization, reproduction, and feeding activity tests, along with the comet assay for in vivo DNA damage evaluation. Recovery from long-term exposure was also assessed. In the F5 generation, the results revealed that when daphnids were re-exposed to carbendazim, DNA damage was higher in daphnids continuously exposed to carbendazim than those from clean medium. After daphnids were moved to a clean medium, a low recovery potential was observed for DNA damage. Daphnids exposed continuously for 6 generations (F6) to carbendazim displayed an increase in feeding rates when re-exposed to carbendazim compared with F6 daphnids reared in clean medium. Continuous exposure of daphnids to carbendazim induced a significant increase in DNA damage from the F0 to the F12 generation. Deleterious effects of the multigenerational exposure to carbendazim were more prominent at a subcellular level (DNA damage) compared with the individual level. Environ Toxicol Chem 2017;36:383-394. © 2016 SETAC.

  11. Single dietary amino acids control resting egg production and affect population growth of a key freshwater herbivore.

    PubMed

    Koch, Ulrike; Martin-Creuzburg, Dominik; Grossart, Hans-Peter; Straile, Dietmar

    2011-12-01

    The enormous success of the genus Daphnia in freshwater ecosystems is at least partially due to their cyclical parthenogenetic life cycle, in which asexual and sexual reproduction alternate periodically. This temporal change between reproductive strategies allows for (1) rapid population growth via subitaneously developing eggs when environmental conditions are appropriate and (2) the maintenance of genetic diversity via sexual reproduction and the production of resting eggs when environmental conditions deteriorate. We show here that dietary amino acids are involved in triggering the switch between reproductive modes in Daphnia pulex. Supplementation experiments demonstrate that specific dietary amino acids, in particular arginine and histidine, avert crowding-induced resting egg production, enhance subitaneous reproduction by increasing algal food quality and, as a combined effect of both processes, increase population growth rates. These findings suggest that the availability of single dietary amino acids potentially affects the seasonal dynamics and long-term persistence of Daphnia populations in the field, which may have consequences for the efficiency of carbon transfer and thus the trophic structure of freshwater food webs.

  12. Freshwater Harmful Algal Blooms

    EPA Pesticide Factsheets

    EPA is seeking regular and early career applications proposing innovative research on the prediction, prevention, control and mitigation of freshwater HABs as well as the drivers, life cycle patterns, and fate of and effects from from less-common, less

  13. Using Daphnia to Teach Critical Thinking about Biological Research.

    ERIC Educational Resources Information Center

    Gray, Dianne

    1996-01-01

    Lists suggestions for improving experiments involving effects of various chemicals on Daphnia heart rate. Concludes that the real value of these experiments lies in what they teach about variations in the response of living things to chemicals and the difficulties researchers encounter when doing experiments with living things. (JRH)

  14. A DAPHNIA MAGNA SHORT-TERM SURVIVAL AND GROWTH TEST

    EPA Science Inventory

    With the change in acceptable test temperatures for invertebrate toxicity tests from <20oC to 25oC, it is now possible to use Daphnia magna for short-term chronic testing. When cultured at 25oC the dry weight of <24 hr old D. magna ranges from 7 to 15 g depending upon nutrition,...

  15. Evaluation of MWNT toxic effects on daphnia and zebrafish embryos

    NASA Astrophysics Data System (ADS)

    Olasagasti, Maider; Alvarez, Noelia; Vera, Carolina; Rainieri, Sandra

    2009-05-01

    Organisms of daphnia (Daphnia magna) and zebrafish (Danio rerio) embryos were exposed to a range of different concentrations of COOH-functionalized MWCNT suspended in an aqueous solution of Tween 20. Immobilization of daphnia and growth retardation, inhibition and malformation of zebrafish embryos were the endpoints tested after 24 and 48 hours. Immobilization of daphnia could be observed from 3 to 16 ppm and an increasing mortality of zebrafish embryo was detected at all the concentration tested. To identify more subtle toxic effects, we took advantage of the extensive information available on the zebrafish genome and monitored by RT-PCR the expression patterns of different zebrafish genes that could act as toxicity bio-markers. At some of the concentrations tested, changes in the expression profiles of the genes examined were detected. Our results suggest that MWCNT could potentially represent a risk to human health and environment, therefore a wider range of concentrations and further testing of this molecules should be carried out to define possible limitations in their use.

  16. Effects of the artificial sweetener sucralose on Daphnia magna and Americamysis bahia survival, growth and reproduction.

    PubMed

    Huggett, D B; Stoddard, K I

    2011-10-01

    The artificial sweetener sucralose has been detected in municipal wastewater effluent and surface waters at concentrations ranging from ng/L to low μg/L. Few chronic ecotoxicological data are available in the peer reviewed literature with respect to sucralose. To address this data gap, 21 d Daphnia magna and 28 d Americamysis bahia (mysid shrimp) studies were conducted to assess the effects of sucralose on the survival, growth and reproduction of these organisms. Concentrations ⩽1800mg/L resulted in no statistically significant reduction in D. magna survival or reproduction. Survival, growth and reproduction of mysid shrimp were unaffected by ⩽93mg/L sucralose. The no observable effect concentration (NOEC) and lowest observable effect concentration (LOEC) for the D. magna study were 1800 and >1800mg/L, respectively. The NOEC and LOEC for the mysid study were 93 and >93mg/L, respectively. Collectively, these data suggest that the concentrations of sucralose detected in the environment are well below those required to elicit chronic effects in freshwater or marine invertebrates.

  17. Physiological and biochemical perturbations in Daphnia magna following exposure to the model environmental estrogen diethylstilbestrol

    SciTech Connect

    Baldwin, W.S.; Milam, D.L.; LeBlanc, G.A.

    1995-06-01

    The estrogenic properties of many environmental contaminants, such as DDE and PCBs, have been associated with reproductive failure in a variety of vertebrate species. While estrogens have been measured in many invertebrate species, the function of this hormone in invertebrates is controversial. The objective of the present study was to identify possible physiological and biochemical target sites for the estrogenic effects of some xenobiotics on the freshwater crustacean Daphnia magna using the model environmental estrogen diethylstilbestrol (DES). Chronic exposure of daphnids to 0.50 mg/L DES reduced molting frequency among first-generation juveniles and decreased fecundity of second-generation daphnids. Adult first-generation daphnids chronically exposed to DES, as well as adult daphnids acutely exposed to DES for only 48 h, were examined for steroid hormone metabolic capabilities using testosterone as the model steroid. The rate of elimination of two major hydroxylated metabolites of testosterone was significantly reduced, and elimination of glucose conjugates of testosterone was significantly elevated from exposure to 0.50 mg/L DES. These results demonstrate that multigeneration exposure of daphnids to DES results in reduced fecundity and altered steroid metabolic capabilities. Thus, some arthropods, like vertebrates, are sensitive to the effects of endocrine-disrupting chemicals.

  18. Selection on incremental variation of eye size in a wild population of Daphnia.

    PubMed

    Brandon, C S; James, T; Dudycha, J L

    2015-11-01

    Several studies of eye morphology have analysed macroevolutionary patterns in the diversity of eyes, and although these studies are often linked to environment or behaviour, they provide only indirect evidence of selection. Specific data to show the microevolutionary potential for adaptation by natural selection in eye morphology have been lacking. We document directional selection on eye size, an important determinant of visual capabilities, in a wild population of the freshwater microcrustacean Daphnia. We show that even slight changes in eye size may have major consequences for fitness. An increase in eye diameter of 19.9 μm - slightly more than one standard deviation - is associated with an increase in clutch size of one egg, or an increase of nearly 20% of the mean clutch size. Furthermore, relative eye size is genetically variable and thus could evolve in response to the observed selective pressure. We conclude that selection on incremental variation in eye size may have led to differences observed on broader taxonomic scales.

  19. Cohorts and populations in chronic toxicity studies with Daphnia magna: a cadmium example

    SciTech Connect

    van Leeuwen, C.J.; Luttmer, W.J.; Griffioen, P.S.

    1985-02-01

    Two semistatic life table experiments with Daphnia magna were carried out on reconstituted and Lake Ijssel water. The nontoxic concentrations for cadmium with respect to the intrinsic rate of natural increase, derived from age-specific survival and fecundity were 1 and 3.2 micrograms/liter, respectively. Body length appeared to be a sensitive parameter. A third intermittent-flow experiment was started with small, exponentially growing populations. These populations had a stable age distribution, were composed of cohorts of different ages and showed an almost perfect logistic growth. Cadmium was shown to reduce the upper numerical limit (carrying capacity) for D. magna and was inversely related to this parameter: log Y = 2.85 -0.20 log (Cd); r = -0.99. A nontoxic concentration could not be established. Based on the background concentration of cadmium, a freshwater quality criterion of 0.1 microgram/liter is proposed. The results are used to discuss several shortcomings of the current methods. Finally it is stated that the introduction of the concepts of population dynamics in reproduction tests with D. magna is a realistic step towards ecotoxicology.

  20. The effect of a low iron diet and early life methylmercury exposure in Daphnia pulex

    PubMed Central

    Hudson, Sherri L.; Doke, Dzigbodi A.; Gohlke, Julia M.

    2016-01-01

    Iron (Fe) deficiency increases risk for adverse health outcomes in humans; however little is known about the potential interaction with methylmercury (MeHg) exposure. Studies testing multiple stressor hypotheses are expensive and time consuming in mammalian model systems; therefore, determining relevance of alternative models is important. Daphnia pulex were fed standard or low-Fe diets of freshwater algae, Ankistrodesmus falcatus. MeHgCl (1600 ng/L) or vehicle was added to culture media for 24 h during early life, and the combinatorial effects of a low-Fe diet and MeHg exposure on lifespan, maturation time, and reproduction were evaluated. Lipid storage effects were measured using image analysis of Oil Red O staining and triacylglyceride quantification. Our results show a dose-dependent reduction in lifespan in D. pulex fed low Fe diets. Lipid analysis suggests an interactive effect of diet and MeHg exposure, with MeHg exposure increasing lipid storage in D. pulex fed a low-Fe diet. These findings suggest the effects of dietary iron intake and early life MeHg exposure in D. pulex may be mediated by changes in energetics that result in differential lipid storage. Therefore, lipid storage in D. pulex may be a useful screen for detecting long-term effects of multiple stressors early in life. PMID:26806633

  1. Daphnia magna transcriptome by RNA-Seq across 12 environmental stressors

    PubMed Central

    Orsini, Luisa; Gilbert, Donald; Podicheti, Ram; Jansen, Mieke; Brown, James B.; Solari, Omid Shams; Spanier, Katina I.; Colbourne, John K.; Rush, Douglas; Decaestecker, Ellen; Asselman, Jana; De Schamphelaere, Karel A.C.; Ebert, Dieter; Haag, Christoph R.; Kvist, Jouni; Laforsch, Christian; Petrusek, Adam; Beckerman, Andrew P.; Little, Tom J.; Chaturvedi, Anurag; Pfrender, Michael E.; De Meester, Luc; Frilander, Mikko J.

    2016-01-01

    The full exploration of gene-environment interactions requires model organisms with well-characterized ecological interactions in their natural environment, manipulability in the laboratory and genomic tools. The waterflea Daphnia magna is an established ecological and toxicological model species, central to the food webs of freshwater lentic habitats and sentinel for water quality. Its tractability and cyclic parthenogenetic life-cycle are ideal to investigate links between genes and the environment. Capitalizing on this unique model system, the STRESSFLEA consortium generated a comprehensive RNA-Seq data set by exposing two inbred genotypes of D. magna and a recombinant cross of these genotypes to a range of environmental perturbations. Gene models were constructed from the transcriptome data and mapped onto the draft genome of D. magna using EvidentialGene. The transcriptome data generated here, together with the available draft genome sequence of D. magna and a high-density genetic map will be a key asset for future investigations in environmental genomics. PMID:27164179

  2. Effects of Microcystis aeruginosa on life history of water flea Daphnia magna

    NASA Astrophysics Data System (ADS)

    Liu, Liping; Li, Kang; Chen, Taoying; Dai, Xilin; Jiang, Min; Diana, James S.

    2011-07-01

    Cyanobacterial blooms in eutrophic freshwater systems are a worldwide problem, creating adverse effects for many aquatic organisms by producing toxic microcystins and deteriorating water quality. In this study, microcystins (MCs) in Microcystis aeruginosa, and Daphnia magna exposed to M. aeruginosa, were analyzed by HPLC-MS, and the effects of M. aeruginosa on D. magna were investigated. When D. magna was exposed to M. aeruginosa for more than 2 h, Microcystin-LR (MC-LR) was detected. When exposed to 1.5 × 106, 3 × 106, 0.75 × 107, and 1.5 × 107 cell/mL of M. aeruginosa for 96 h, average survival of D. magna for treatments were 23.33%, 33.33%, 13.33%, 16.67%, respectively, which were significantly lower than the average 100% survival in the control group ( P < 0.05). The adverse effects of M. aeruginosa on body length, time for the first brood, brood numbers, gross fecundity, lifespan, and population growth of D. magna were density-dependent. These results suggest that the occurrence of M. aeruginosa blooms could strongly inhibit the population growth of D. magna through depression of survival, individual growth and gross fecundity. In the most serious situations, M. aeruginosa blooms could undermine the food web by eliminating filter-feeding zooplankton, which would destroy the ecological balance of aquaculture water bodies.

  3. Effect of Clonal Selection on Daphnia Tolerance to Dark Experimental Conditions

    PubMed Central

    Gitzen, Robert A.; Williamson, Craig E.; González, Maria J.

    2016-01-01

    Recent studies have demonstrated substantial effects of environmental stress that vary among clones. Exposure to ultraviolet radiation (UV) is an important abiotic stressor that is highly variable in aquatic ecosystems due to diel and seasonal variations in incident sunlight as well as to differences in the UV transparency of water among water bodies, the depth distribution of organisms, and the ability of organisms to detect and respond to UV. In contrast to the convention that all UV is damaging, evidence is accumulating for the beneficial effects of exposure to low levels of UV radiation. Whereas UV has been frequently observed as the primary light-related stressor, herein we present evidence that dark conditions may be similarly “stressful” (reduction of overall fitness), and stress responses vary among clones of the freshwater crustacean Daphnia parvula. We have identified a significant relationship between survivorship and reduced fecundity of clones maintained in dark conditions, but no correlation between tolerance of the clones to dark and UV radiation. Low tolerance to dark conditions can have negative effects not only on accumulated stresses in organisms (e.g. the repair of UV-induced damage in organisms with photolyase), but potentially on the overall physiology and fitness of organisms. Our results support recent evidence of the beneficial effects of low-level UV exposure for some organisms. PMID:27434210

  4. Finely tuned response of native prey to an invasive predator in a freshwater system.

    PubMed

    Bourdeau, Paul E; Pangle, Kevin L; Reed, Emily M; Peacor, Scott D

    2013-07-01

    Lack of shared evolutionary history reduces the expectation that native prey will detect and respond to invasive predators. Four mechanisms may explain the adaptive response that is nevertheless seen in various systems: prey may perceive the invasive predator through cue similarity with preexisting predators, cues of conspecifics eaten by the invasive predator, a learned response based on experience with the invasive predator (e.g., cue association), and cues from the invasive predator that are specific to it. We performed laboratory experiments in which zooplankton (Daphnia mendotae) responded adaptively to the zooplanktivore Bythotrephes longimanus (migrating downward), showed no response to taxonomically similar predatory cladocerans, and responded adaptively to more taxonomically distant native fish (migrating downward) and native shrimp (migrating upward). Conspecific cues associated with Bythotrephes predation actually reduced the response of D. mendotae to Bythotrephes. Combined with previous experiments that rule out learning, our experiments rule out the first three mechanisms above, demonstrating that D. mendotae respond to cues specific to and produced directly by Bythotrephes. This finely tuned response may be retained from an ancestral species that coevolved with Bythotrephes in its native range, or may have rapidly evolved due to strong selection by the invasive predator.

  5. Community and ecosystem responses to a pulsed pesticide disturbance in freshwater ecosystems.

    PubMed

    Downing, Amy L; DeVanna, Kristen M; Rubeck-Schurtz, C Nichole; Tuhela, Laura; Grunkemeyer, Heather

    2008-08-01

    Pesticides have been shown to be detrimental to key groups of freshwater organisms including cladocerans, odonates, and amphibians. However, less is known about the response of freshwater communities and ecosystems to pesticide disturbances as they occur in nature. Using outdoor aquatic mesocosms, we assembled identical and diverse replicate freshwater plankton food webs obtained from an adjacent pond. We established three pesticide treatments consisting of pulses of a common pesticide Sevin with the active ingredient carbaryl, at concentrations of 0.1, 1 and 20 microg carbaryl/ml, and a pesticide-free control treatment. We monitored the response of microbial, phytoplankton, and zooplankton communities in addition to oxygen concentrations. Carbaryl concentrations peaked shortly after Sevin application and degraded quickly and treatment differences were undetectable after 30 days. Zooplankton richness, diversity, abundance, and oxygen concentrations all decreased in pulsed treatments, while phytoplankton and microbial abundance increased. Zooplankton composition in the high pesticide treatment consisted primarily of rotifers as compared to dominance by copepods in the other three treatments. While many of the community and ecosystem properties showed signs of recovery within 40 days after the pulsed pesticide disturbance, important and significant differences remained in the microbial, phytoplankton and zooplankton communities after the pesticide degraded.

  6. Freshwater shrimps as sensitive test species for the risk assessment of pesticides in the tropics.

    PubMed

    Daam, Michiel A; Rico, Andreu

    2016-08-17

    The aquatic risk assessment of pesticides in tropical areas has often been disputed to rely on toxicity data generated from tests performed with temperate species. Given the differences in ecosystem structure between temperate and tropical ecosystems, test species other than those used in temperate regions have been proposed as surrogates for tropical aquatic effect assessments. Freshwater shrimps, for example are important components of tropical freshwater ecosystems, both in terms of their role in ecosystem functioning and their economic value. In the present study, available toxicity data of (tropical and sub-tropical) freshwater shrimps for insecticides and fungicides were compiled and compared with those available for Daphnia magna and other aquatic invertebrates. Freshwater shrimps appeared to be especially sensitive to GABA-gated chloride channel antagonist and sodium channel modulator insecticides. However, shrimp taxa showed a moderate and low sensitivity to acetylcholinesterase inhibiting insecticides and fungicides respectively. Implications for the use of freshwater shrimps in tropical pesticide effect assessments and research needs are discussed.

  7. Toxic effect of selenium on the zooplankton, Daphnia magna and Daphnia pulicaria, in water and the food source (Chlamydomonas reinhardtii)

    SciTech Connect

    Boyum, K.W.

    1984-01-01

    Acute and chronic toxicity experiments were performed on the zooplankton, Daphnia magna and Daphnia pulicaria, to investigate the toxicity of selenium on these aquatic invertebrates. The acute 48 h LC/sub 50/ of sodium selenate for Daphnia magna and Daphnia pulicaria were 1.01 and 0.25 mg Se/1, respectively. The 48 h LC/sub 50/ of sodium selenite for D. magna and D. pulicaria were 0.45 and 0.006 mg Se/1, respectively. Chronic 28-day toxicity tests were performed on D. magna at 0.05, 0.10, 0.50, and 1.00 mg Se/1 as sodium selenate in the water and with two food types. One food type was algae raised in clean Lake Michigan water and the second treatment was algae raised in media with selenium concentrations corresponding to those in the water cited above. When compared to Daphnia fed selenium-free algae, D. magna fed selenium-laden algae had greater survival, a greater number of offspring produced, and a greater intrinsic growth rate, r, at the toxicant concentration in the water of 0.05, 0.10, and 0.50 mg Se/1. These parameters were, however, lower than those observed in the controls. Uptake of /sup 75/Se as sodium selenate in D. magna was reduced in the presence of selenium-laden algae and DL-selenomethionine, while L-methionine increased the uptake of /sup 75/Se. Selenium bound to an amino acid such as Dl-selenomethionine or organically bound within an algal food source appears to be preferentially incorporated thereby reducing the uptake of inorganic forms from the water.

  8. Toxicity to freshwater organisms from oils and oil spill chemical treatments in laboratory microcosms.

    PubMed

    Bhattacharyya, S; Klerks, P L; Nyman, J A

    2003-01-01

    Toxicity and temporal changes in toxicity of freshwater-marsh-microcosms containing South Louisiana Crude (SLC) or diesel fuel and treated with a cleaner or dispersant, were investigated using Chironomus tentans, Daphnia pulex, and Oryzias latipes. Bioassays used microcosm water (for D. pulex and O. latipes) or soil slurry (for C. tentans) taken 1,7, 31, and 186 days after treatment. SLC was less toxic than diesel, chemical additives enhanced oil toxicity, the dispersant was more toxic than the cleaner, and toxicities were greatly reduced by day 186. Toxicities were higher in the bioassay with the benthic species than in those with the two water-column species. A separate experiment showed that C. tentans' sensitivity was intermediate to that of Tubifex tubifex and Hyallela azteca. Freshwater organisms, especially benthic invertebrates, thus appear seriously effected by oil under the worst-case-scenario of our microcosms. Moreover, the cleaner and dispersant tested were poor response options under those conditions.

  9. Toxicological effects of military fog oil obscurant on Daphnia magna and Ceriodaphnia dubia in field and laboratory exposures.

    PubMed

    Cropek, Donald M; Esarey, Joan C; Conner, Cassie L; Goran, Jacob M; Smith, Thomas; Soucek, David J

    2008-08-01

    Our purpose was to determine if the acute and sub-lethal effects of fog oil, an obscurant used for military training, could be observed in realistic field exposures. To this end, we exposed Daphnia magna to oil fogs under actual release conditions at a U.S. Army training site. Guided by field investigations, acute toxicity experiments were conducted in the laboratory with the more sensitive species Ceriodaphnia dubia to test the hypothesis that dissolution of fog oil constituents into water is minimal and actual contact by organisms with the water surface is required to cause toxicity. We conducted further experiments to test the hypothesis that vaporization of fog oil alters its chemical composition and toxicity to freshwater invertebrates. In the field, daphnid mortality was minimal more than 5 m from the point of fog generation, but sub-lethal effects were more extensive. Both field and laboratory experiments suggested that physical contact with oils on the water surface was the most important factor driving toxicity. To our knowledge, this is the first attempt to evaluate toxicological endpoints with freshwater invertebrates in field exposures with fog oil.

  10. Toxicity of brominated volatile organics to freshwater biota.

    PubMed

    Binet, Monique T; Stauber, Jenny L; Adams, Merrin S; Rhodes, Stuart; Wech, Janine

    2010-09-01

    As part of a larger study investigating the fate and effects of brominated volatile organic compounds (VOCs) in contaminated groundwaters discharging to surface waters, the toxicity of 1,2 dibromoethene (DBE) and 1,1,2-tribromoethene (TriBE) to freshwater aquatic biota was investigated. Their toxicity to bacteria (Microtox(R)), microalgae (Chlorella sp.), cladocerans (Ceriodaphnia dubia), duckweed (Lemna sp.) and midges (Chironomus tepperi) was determined after careful optimization of the test conditions to minimize chemical losses throughout the tests. In addition, concentrations of DBE and TriBE were carefully monitored throughout the bioassays to ensure accurate calculation of toxicity values. 1,2-Dibromoethene showed low toxicity to most species, with concentrations to cause 50% lethality or effect (LC/EC50 values) ranging from 28 to 420 mg/L, 10% lethality or effect (LC/EC10 values) ranging from 18 to 94 mg/L and no-observed-effect concentrations (NOECs) ranging from 22 to 82 mg/L. 1,1,2-Tribromoethene was more toxic than DBE, with LC/EC50 values of 2.4 to 18 mg/L, LC/EC10 values of 0.94 to 11 mg/L and NOECs of 0.29 to 13 mg/L. Using these limited data, together with data from the only other published study on TriBE, moderate-reliability water quality guidelines (WQGs) were estimated from species sensitivity distributions. The proposed guideline trigger values for 95% species protection with 50% confidence were 2 mg/L for DBE and 0.03 mg/L for TriBE. The maximum concentrations of DBE and TriBE in nearby surface waters (3 and 1 microg /L, respectively) were well below these WQGs, so the risk to the freshwater environment receiving contaminated groundwater inflows was considered to be low, with hazard quotients <1 for both VOCs. Environ.

  11. Effects of 17alpha-ethinylestradiol on the reproduction of the cladoceran species Ceriodaphnia reticulata and Sida crystallina.

    PubMed

    Jaser, Wolfgang; Severin, Gabriele F; Jütting, Uta; Jüttner, Ingrid; Schramm, Karl Werner; Kettrup, Antonius

    2003-01-01

    Single-species tests allow the assessment of chronical effects of endocrine disruptors on organisms under laboratory conditions. In the current study, three-generation tests with Ceriodaphnia reticulata and Sida crystallina were carried out to examine the influence of the synthetic hormone 17alpha-ethinylestradiol (EE) on the reproduction of these cladoceran species. For each species, six different concentrations (10-500 microg/l EE) and two controls were tested with eight replicates for a duration of 4 weeks. The test was initiated by transferring one neonate individual into a test vessel which was incubated under standardized conditions. Every 2 days, the medium was renewed and life history parameters such as survivorship of the adults and juveniles, clutch size, first appearance and number of produced offspring were investigated. Acute toxicity tests showed that C. reticulata (EC50 (24 h) 1814 microg/l) was more sensitive towards the substance compared to S. crystallina (EC50 (24 h) >4100 microg/l). The juvenile phase of S. crystallina was significantly shorter at concentrations above 100 microg/l EE. For C. reticulata, 17alpha-ethinylestradiol caused a higher mortality of the newly hatched juveniles at EE concentrations above 200 microg/l. No effects were found for mortality of adult animals, birth rate, number of juveniles per female and net reproduction rate of S. crystallina and C. reticulata. Thus, sublethal effects on parental generation exposed to EE lead to disturbances in reproduction and to affection of their offspring. Negative consequences for the population dynamic cannot be excluded, e.g. the decrease of a population.

  12. An evaluation of the residual toxicity and chemistry of a sodium hydroxide-based ballast water treatment system for freshwater ships.

    PubMed

    Elskus, Adria A; Ingersoll, Christopher G; Kemble, Nile E; Echols, Kathy R; Brumbaugh, William G; Henquinet, Jeffrey W; Watten, Barnaby J

    2015-06-01

    Nonnative organisms in the ballast water of freshwater ships must be killed to prevent the spread of invasive species. The ideal ballast water treatment system (BWTS) would kill 100% of ballast water organisms with minimal residual toxicity to organisms in receiving waters. In the present study, the residual toxicity and chemistry of a BWTS was evaluated. Sodium hydroxide was added to elevate pH to >11.5 to kill ballast water organisms, then reduced to pH <9 by sparging with wet-scrubbed diesel exhaust (the source of CO2 ). Cladocerans (Ceriodaphnia dubia), amphipods (Hyalella azteca), and fathead minnows (Pimephales promelas) were exposed for 2 d to BWTS water under an air atmosphere (pH drifted to ≥9) or a 2.5% CO2 atmosphere (pH 7.5-8.2), then transferred to control water for 5 d to assess potential delayed toxicity. Chemical concentrations in the BWTS water met vessel discharge guidelines with the exception of concentrations of copper. There was little to no residual toxicity to cladocerans or fish, but the BWTS water was toxic to amphipods. Maintaining a neutral pH and diluting BWTS water by 50% eliminated toxicity to the amphipods. The toxicity of BWTS water would likely be minimal because of rapid dilution in the receiving water, with subsurface release likely preventing pH rise. This BWTS has the potential to become a viable method for treating ballast water released into freshwater systems.

  13. Influence of food, aquatic humus, and alkalinity on methylmercury uptake by Daphnia magna

    SciTech Connect

    Monson, B.A.; Brezonik, P.L.

    1999-03-01

    Six-day-old Daphnia magna were exposed to low concentrations of methylmercury (MeHg) in synthetic freshwater and synthetic food. Uptake kinetics were determined in 24- to 72-h experiments, measuring both the loss of Hg from water and accumulation in D. magna. Dose-uptake response was linear for MeHg concentrations up to 4.0 ng/L; an initial concentration of 2.0 ng/L was used when other factors were varied. Concentrations of total Hg and MeHg in water and D. magna were measured in treatments with varied hardness and alkalinity, aquatic humus (AH), and food spiked with MeHg versus water spiked with MeHg. Uptake rate coefficients were derived from two versions of a first-order, two-compartment model. The first version assumed constant MeHg concentration; the second accounted for changing MeHg concentration in water over time. Both models accounted for a nonzero starting concentration of MeHg in plankton. Fitted rate coefficients were higher for the second model than the first: the uptake coefficient (k{sub u}) was nine times higher; the depuration coefficient (k{sub d}) was twice as high. Assuming a constant MeHg concentration for a one-time spike thus underestimated the rate coefficient. The source of MeHg was compared by exposing D. magna for 48 h to MeHg at 2 ng/L in food or water. Daphnia magna accumulated significantly more inorganic Hg (i.e., Hg{sup 2+}) from spiked food than from spiked water, but accumulation of MeHg was the same from both sources. A similar response was found when D. magna were exposed to a lake water extraction of AH at concentrations of C at 3 and 10 mg/L. At the higher AH concentration, total Hg in daphnids was higher, but MeHg was lower, suggesting that AH was a source of inorganic Hg but reduced the bioavailability of MeHg. Exposure of D. magna to MeHg at 2 ng/L in hard or soft water adjusted to pH 6.7 showed no significant difference in MeHg uptake, supporting an argument that hardness and alkalinity per se do not affect MeHg uptake by

  14. Acute dysprosium toxicity to Daphnia pulex and Hyalella azteca and development of the biotic ligand approach.

    PubMed

    Vukov, Oliver; Smith, D Scott; McGeer, James C

    2016-01-01

    The toxicological understanding of rare earth elements (REEs) in the aquatic environment is very limited but of increasing concern. The objective of this research is to compare the toxicological effect of the REE dysprosium to the freshwater invertebrates Daphnia pulex and Hyalella azteca and in the more sensitive organism, understand the toxicity modifying influence of Ca, Na, Mg, pH and dissolved organic matter (DOM). Standard methods (Environment Canada) were followed for testing and culture in media of intermediate hardness (60mg CaCO3 mg/L) at pH 7.8 with Ca at 0.5, Na 0.5, Mg 0.125 (mM) and 23°C. Acute toxicity tests were done with <24h old neonates for 48h in the case of D. pulex and with 2-9 days old offspring for 96h tests with Hyalella. The potential protective effect of cationic competition was tested with Ca (0.5-2.0mM), Na (0.5-2.0mM) and Mg (0.125-0.5mM). The effect of pH (6.5-8.0) and Suwannee River DOM complexation (at dissolved organic carbon (DOC) concentrations of 9 and 13mg C/L) were evaluated. Dissolved Dy concentrations were lower than total (unfiltered) indicating precipitation, particularly at higher concentrations. Acute toxicity of Dy to H. azteca and D. pulex revealed Hyalella to be 1.4 times more sensitive than Daphnia. Additions of Ca and Na but not Mg provided significant protection against Dy toxicity to Hyalella. Similarly, low pH was associated with reduction in toxicity. Exposures which were pH buffered with and without MOPS were significantly different and indicated that MOPS enhanced Dy toxicity. DOM also mitigated Dy toxicity. Biotic ligand based parameters (LogK values) were calculated based on free ion relationships as determined by geochemical equilibrium modeling software (WHAM ver. 7.02). The logK value for Dy(3+) toxicity to Hyalella was 7.75 while the protective influence of Ca and Na were 3.95 and 4.10, respectively. This study contributes data towards the development of site specific water quality guidelines and

  15. Production and utilization of dissolved adenosine 5'-triphosphate in marine and freshwater ecosystems

    SciTech Connect

    Peele, E.R.

    1985-01-01

    Concentrations of dissolved adenosine triphosphate (DATP) were influenced primarily by in situ biological processes such as uptake by heterotrophic microorganisms and release by either phytoplankton or zooplankton or through zooplankton-phytoplankton interactions. Rapid turnover of dissolved ATP via uptake by bacterioplankton was observed in an estuary (Sapelo Island, Georgia) and two freshwater lakes (Lake Oglethorpe, Georgia and Lago Lake, Georgia). Turnover times for DATP, based on microbial assimilation of (/sup 3/H)ATP, were on the order of hours to days in all three environments. DATP was not taken up intact by the natural microbial populations; rather, it was degraded to adenine, ribose and inorganic phosphate prior to or during transport. The primary mechanism for DATP uptake was via dephosphorylation of the nucleotide and cleavage of resultant nucleoside to adenine and ribose which then entered the cells by separate transport systems. The rate of DATP assimilation by freshwater microorganisms varied markedly-over a diel cycle. Results from microcosm experiments in which the authors compared the rates of DATP release by phytoplankton (Chlamydomonas sp.) alone, zooplankton (Daphnia sp.) alone or phytoplankton and zooplankton together under feeding conditions supported those hypotheses. Net extracellular release of DATP by Chlamydomonas was negligible in short-term experiments, and in systems containing both Daphnia and Chlamydomonas, changes in DATP over time were approximately 3-fold greater than the sum of changes observed in systems containing either organism alone.

  16. Toxicity Determination of Explosive Contaminated Soil Leachates to Daphnia magna Using an Adapted Toxicity Characteristic Leaching Procedure

    DTIC Science & Technology

    1993-06-01

    An adapted toxicity characteristic leaching procedure was used to determine toxicity of soils to Daphnia magna . Soil samples were collected from U.S...vol/vol). Contaminated boils, Munition residues, Daphnia magna , EC50 Toxicity.

  17. Medical-biological aspects of radiation effects in Daphnia magna

    NASA Astrophysics Data System (ADS)

    Sarapultseva, E.; Uskalova, D.; Savina, N.; Ustenko, K.

    2017-01-01

    We have shown that γ-irradiation at doses of 100 and 1000 mGy significantly compromised fecundity and reproductive success of the directly exposed D. magna. These effects were also observed among the non-exposed first-generation progeny of irradiated parents, thus implying the manifestation of transgenerational effects in Daphnia. We have also shown that compromised viability of irradiated D. magna can be attributed cytotoxic effects of irradiation. It would therefore appear that the compromised viability may be attributed to the cytotoxic effects resulted from epigenetic changes affecting some metabolic pathways involved in detoxification of free-radicals. Additionally we have analyzed more distant progeny of irradiated at doses of 10, 100 and 1000 mGy Daphnia. Our data demonstrated that multicellular crustacean D. magna represent a very useful experimental model for analyse of long-term effects of ionising radiation at the organismal level.

  18. Effects of stoichiometric dietary mixing on Daphnia growth and reproduction.

    PubMed

    Acharya, Kumud; Kyle, Marcia; Elser, James J

    2004-02-01

    Herbivores often encounter nutritional deficiencies in their diets because of low nutrient content of plant biomass. Consumption of various diet items with different nutrient contents can potentially alleviate these nutritional deficiencies. However, most laboratory studies and modeling of herbivorous animals have been done with diets in which all food has uniform nutrient content. It is not clear whether heterogeneous versus uniform food of equal overall nutrient content is of equivalent nutritional value. We tested the effects of dietary mixing on performance of a model organism, Daphnia. We fed two species of Daphnia ( D. galeata, D. pulicaria) with diets of equivalent bulk stoichiometric food quality (C:P) and studied whether they would produce equivalent performance when C:P was uniform among cells or when the diet involved a mixture of high C:P and low C:P cells. Daphnia were fed saturating and limiting concentrations of a uniform food of moderate C:P (UNI) or mixtures (MIX) of high C:P (LOP) and low C:P (HIP) algae prepared to match C:P in UNI. Daphnia were also fed HIP and LOP algae separately. Juvenile growth rate and adult fecundity were measured. D. galeata performance in UNI and MIX treatments did not differ, indicating that partitioning of C and P among particles did not affect dietary quality. Similarly, D. pulicaria's performance was similar in the MIX and UNI treatments but only at low food abundance. In the high food treatment, both growth and reproduction were higher in the MIX treatment, indicating some benefit of a more heterogeneous diet. The mechanisms for this improvement are unclear. Also, food quality affected growth and reproduction even at low food levels for both D. pulicaria and D. galeata. Our results indicate that some species of zooplankton can benefit from stoichiometric heterogeneity on diet.

  19. Collaborative Study of Daphnia magna Static Renewal Assays.

    DTIC Science & Technology

    1986-01-01

    Report for Contract DAMD17-80-C-OO11, titled "Determination of the Toxicity to Aquatic Orarisms of HMX and Related Wastewater Constituents." The...identify by block number) Collaborative, interlaboratory, Daphnia magna, static renewal, copper. sodium pentachlorophenate, toxicity , 120. A(ITRAcr...identified to all collaborative laboratories. This material, sodium pentachlorophenate (NaPCP), served as the reference toxicant , and enabled the

  20. Acute toxicity and QSAR of chlorophenols on Daphnia magna

    SciTech Connect

    Devillers, J.; Chambon, P.

    1986-10-01

    Chlorophenols which are released into natural waters from various industrial processes and from agricultural uses have been recognized as a group of chemical substances potentially hazardous to the aquatic environment. Therefore it is important to estimate their toxic impact on biota. Thus, the scope of this research was to obtain acute toxicity data for seventeen chlorophenols towards Daphnia magna and to explore the possibilities of deriving QSAR's (quantitative structure-activity relationship) from the above values.

  1. Responses of alkaline phosphatase activity in Daphnia to poor nutrition.

    PubMed

    Wagner, Nicole D; Frost, Paul C

    2012-09-01

    The use of biochemical and molecular indices of nutritional stress have recently been promoted for their potential ability to assess the in situ nutritional state of zooplankton. The development and application of these indicators should at least consider the cross-reactivity with other nutritional stressors. We examined the potential usefulness of body alkaline phosphatase activity (APA) as an indicator of dietary phosphorus (P) stress in Daphnia. We measured growth rate, body P-content, and body APA of two species of Daphnia (D. magna, D. pulex) grown for different periods under diverse dietary conditions. We found P-poor food reduced daphnid growth rates and body P-content, while body APA increased in both species. However, body APA increased in P-sufficient D. magna and D. pulex that were feeding on cyanobacterial compared to green algal food, despite no differences in animal body P content. Body APA increased in D. magna fed P-poor food whether cyanobacterial or algal. Body APA also varied with age and other nutritional stresses (low food quantity, nitrogen-poor algae) in both daphnid species. Our results demonstrate that whole body homogenate APA in Daphnia is not singularly responsive to P-poor food, which will complicate or limit its future usefulness and application as an indicator of dietary P-stress in metazoans.

  2. Silver nanoparticle-specific mitotoxicity in Daphnia magna.

    PubMed

    Stensberg, Matthew C; Madangopal, Rajtarun; Yale, Gowri; Wei, Qingshan; Ochoa-Acuña, Hugo; Wei, Alexander; McLamore, Eric S; Rickus, Jenna; Porterfield, D Marshall; Sepúlveda, Maria S

    2014-12-01

    Silver nanoparticles (Ag NPs) are gaining popularity as bactericidal agents in commercial products; however, the mechanisms of toxicity (MOT) of Ag NPs to other organisms are not fully understood. It is the goal of this research to determine differences in MOT induced by ionic Ag(+) and Ag NPs in Daphnia magna, by incorporating a battery of traditional and novel methods. Daphnia embryos were exposed to sublethal concentrations of AgNO3 and Ag NPs (130-650 ng/L), with uptake of the latter confirmed by confocal reflectance microscopy. Mitochondrial function was non-invasively monitored by measuring proton flux using self-referencing microsensors. Proton flux measurements revealed that while both forms of silver significantly affected proton efflux, the change induced by Ag NPs was greater than that of Ag(+). This could be correlated with the effects of Ag NPs on mitochondrial dysfunction, as determined by confocal fluorescence microscopy and JC-1, an indicator of mitochondrial permeability. However, Ag(+) was more efficient than Ag NPs at displacing Na(+) within embryonic Daphnia, based on inductively coupled plasma-mass spectroscopy (ICP-MS) analysis. The abnormalities in mitochondrial activity for Ag NP-exposed organisms suggest a nanoparticle-specific MOT, distinct from that induced by Ag ions. We propose that the MOT of each form of silver are complementary, and can act in synergy to produce a greater toxic response overall.

  3. Ecological genomics in Daphnia: stress responses and environmental sex determination.

    PubMed

    Eads, B D; Andrews, J; Colbourne, J K

    2008-02-01

    Ecological genomics is the study of adaptation of natural populations to their environment, and therefore seeks to link organism and population level processes through an understanding of genome organization and function. The planktonic microcrustacean Daphnia, which has long been an important system for ecology, is now being used as a genomic model as well. Here we review recent progress in selected areas of Daphnia genomics research. Production of parthenogenetic male offspring occurs through environmental cues, which clearly involves endocrine regulation and has also been studied as a toxicological response to juvenoid hormone analog insecticides. Recent progress has uncovered a putative juvenoid cis-response element, which together with microarray analysis will stimulate further research into nuclear hormone receptors and their associated transcriptional regulatory networks. Ecotoxicological studies indicate that mRNA profiling is a sensitive and specific research tool with promising applications in environmental monitoring and for uncovering conserved cellular processes. Rapid progress is expected to continue in these and other areas, as genomic tools for Daphnia become widely available to investigators.

  4. Freshwater Marsh. Habitat Pac.

    ERIC Educational Resources Information Center

    Fish and Wildlife Service (Dept. of Interior), Washington, DC.

    The materials in this educational packet are designed for use with students in grades 4 through 7. They consist of an overview, three lesson plans and student data sheets, and a poster. The overview describes how the freshwater marsh is an important natural resource for plant, animal, and human populations and how the destruction of marshes causes…

  5. The influence of bacteria-dominated diets on Daphnia magna somatic growth, reproduction, and lipid composition.

    PubMed

    Taipale, Sami J; Brett, Michael T; Pulkkinen, Katja; Kainz, Martin J

    2012-10-01

    We explored how dietary bacteria affect the life history traits and biochemical composition of Daphnia magna, using three bacteria taxa with very different lipid composition. Our objectives were to (1) examine whether and how bacteria-dominated diets affect Daphnia survival, growth, and fecundity, (2) see whether bacteria-specific fatty acid (FA) biomarkers accrued in Daphnia lipids, and (3) explore the quantitative relationship between bacteria availability in Daphnia diets and the amounts of bacterial FA in their lipids. Daphnia were fed monospecific and mixed diets of heterotrophic (Micrococcus luteus) or methanotrophic bacteria (Methylomonas methanica and Methylosinus trichosporium) and two phytoplankton species (Cryptomonas ozolinii and Scenedesmus obliquus). Daphnia neonates fed pure bacteria diets died after 6-12 days and produced no viable offspring, whereas those fed pure phytoplankton diets had high survival, growth, and reproduction success. Daphnia fed a mixed diet with 80% M. luteus and 20% of either phytoplankton had high somatic growth, but low reproduction. Conversely, Daphnia fed mixed diets including 80% of either methane-oxidizing bacteria and 20% Cryptomonas had high reproduction rates, but low somatic growth. All Daphnia fed mixed bacteria and phytoplankton diets had strong evidence of both bacteria- and phytoplankton-specific FA biomarkers in their lipids. FA mixing model calculations indicated that Daphnia that received 80% of their carbon from bacteria assimilated 46 ± 25% of their FA from this source. A bacteria-phytoplankton gradient experiment showed a strong positive correlation between the proportions of the bacterial FA in the Daphnia and their diet, indicating that bacterial utilization can be traced in this keystone consumer using FA biomarkers.

  6. Thermal variation and factors influencing vertical migration behavior in Daphnia populations.

    PubMed

    Glaholt, Stephen P; Kennedy, Meghan L; Turner, Elizabeth; Colbourne, John K; Shaw, Joseph R

    2016-08-01

    The antipredator behavior diel vertical migration (DVM), common in aquatic keystone species Daphnia, involves daily migration from warmer surface waters before dawn to cooler deeper waters after dusk. Plasticity in Daphnia DVM behavior optimizes fitness via trade-offs between growth, reproduction, and predator avoidance. Migration behavior is affected by co-varying biotic and abiotic factors, including light, predator cues, and anthropogenic stressors making it difficult to determine each factor's individual contribution to the variation in this behavior. This study aims to better understand this ecologically significant behavior in Daphnia by: (1) determining how Daphnia pulicaria thermal preferences vary within and among natural populations; (2) distinguishing the role of temperature verses depth in Daphnia vertical migration; and (3) defining how two anthropogenic stressors (copper and nickel) impact Daphnia migratory behavior. Simulated natural lake stratification were constructed in 8L (0.5m tall, 14.5cm wide) water columns to monitor under controlled laboratory conditions the individual effects of temperature gradients, depth, and metal stressors on Daphnia vertical migration. Three major findings are reported. First, while no difference in thermal preference was found among the four populations studied, within lake populations variability among isolates was high. Second, decoupling temperature and depth revealed that depth was a better predictor of Daphnia migratory patterns over temperature. Third, exposure to environmentally relevant concentrations of copper or nickel inhibited classic DVM behavior. These findings revealed the high variability in thermal preference found within Daphnia populations, elucidated the individual roles that depth and temperature have on migratory behavior, and showed how copper and nickel can interfere with the natural response of Daphnia to fish predator cues. Thus contributing to the body of knowledge necessary to predict how

  7. Comparative ovarian microarray analysis of juvenile hormone-responsive genes in water flea Daphnia magna: potential targets for toxicity.

    PubMed

    Toyota, Kenji; Williams, Timothy D; Sato, Tomomi; Tatarazako, Norihisa; Iguchi, Taisen

    2017-03-01

    The freshwater zooplankton Daphnia magna has been extensively employed in chemical toxicity tests such as OECD Test Guidelines 202 and 211. Previously, it has been demonstrated that the treatment of juvenile hormones (JHs) or their analogues to female daphnids can induce male offspring production. Based on this finding, a rapid screening method for detection of chemicals with JH-activity was recently developed using adult D. magna. This screening system determines whether a chemical has JH-activity by investigating the male offspring inducibility. Although this is an efficient high-throughput short-term screening system, much remains to be discovered about JH-responsive pathways in the ovary, and whether different JH-activators act via the same mechanism. JH-responsive genes in the ovary including developing oocytes are still largely undescribed. Here, we conducted comparative microarray analyses using ovaries from Daphnia magna treated with fenoxycarb (Fx; artificial JH agonist) or methyl farnesoate (MF; a putative innate JH in daphnids) to elucidate responses to JH agonists in the ovary, including developing oocytes, at a JH-sensitive period for male sex determination. We demonstrate that induction of hemoglobin genes is a well-conserved response to JH even in the ovary, and a potential adverse effect of JH agonist is suppression of vitellogenin gene expression, that might cause reduction of offspring number. This is the first report demonstrating different transcriptomics profiles from MF and an artificial JH agonist in D. magna ovary, improving understanding the tissue-specific mode-of-action of JH. Copyright © 2016 John Wiley & Sons, Ltd.

  8. Evidence for the Stepwise Stress Model: Gambusia holbrooki and Daphnia magna under acid mine drainage and acidified reference water stress.

    PubMed

    Gerhardt, Almut; Janssens de Bisthoven, Luc; Soares, Amadeu M V

    2005-06-01

    The Stepwise Stress Model (SSM) states that a cascade of regulative behavioral responses with different intrinsic sensitivities and threshold values offers increased behavioral plasticity and thus a wider range of tolerance for environmental changes or pollutant exposures. We tested the SSM with a widely introduced fish Gambusia holbrooki (Girard) (Pisces, Poeciliidae) and the standard laboratory test species Daphnia magna Straus (Crustacea, Daphniidae). The stress was simulated by short-term exposure to acid mine drainage (AMD) and to acidified reference water (ACID). Recording of behavioral responses with the multispecies freshwater biomonitor (MFB) generated continuous time-dependent dose-response data that were modeled in three-dimensional (3D) surface plots. Both the pH-dependent mortalities and the strong linear correlations between pH and aqueous metals confirmed the toxicity of the AMD and ACID gradients, respectively, for fish and Daphnia, the latter being more sensitive. AMD stress at pH < or = 5.5 amplified circadian rhythmicity in both species, while ACID stress did so only in G. holbrooki. A behavioral stepwise stress response was found in both species: D. magna decreased locomotion and ventilation (first step) (AMD, ACID), followed by increased ventilation (second step) (AMD). G. holbrooki decreased locomotion (first step) (AMD, ACID) and increased ventilation at intermediate pH levels (second step) (AMD). Both species, although from different taxonomic groups and feeding habits, followed the SSM, which might be expanded to a general concept for describing the behavioral responses of aquatic organims to pollution. Stepwise stress responses might be applied in online biomonitors to provide more sensitive and graduated alarm settings, hence optimizing the "early warning" detection of pollution waves.

  9. Comments on cladocerans of crater lakes of the Nevado de Toluca Volcano (Central Mexico), with the description of a new species, Alona manueli sp. nov.

    PubMed

    Sinev, Artem Y; Zawisza, Edyta

    2013-01-01

    Cladoceran communities of two lakes of Nevado de Toluca Volcano, Central Mexico, were studied. A new species of Aloninae, Alona manueli sp. nov., is described. It was previously confused with Palearctic Alona intermedia Sars, 1862, but clearly differs from it in the morphology of postabdomen, head shield and head pores, and thoracic limbs. Position of Alona manueli sp. nov. within the genus is unclear, it did not belong to any species-group within Alona s. lato. Other species recorded in the studied lakes are Alona ossiani Sinev, 1998, Alonella pulchella Herrick, 1884, Chydorus belonging to sphaericus-group, Eurycercus longirostris Hann, 1982 and Pleuroxus cf. denticulatus Birge, 1879.

  10. The Effects of Natural and Anthropogenic Microparticles on Individual Fitness in Daphnia magna

    PubMed Central

    Schür, Christoph; Jarsén, Åsa; Gorokhova, Elena

    2016-01-01

    Concerns are being raised that microplastic pollution can have detrimental effects on the feeding of aquatic invertebrates, including zooplankton. Both small plastic fragments (microplastics, MPs) produced by degradation of larger plastic waste (secondary MPs; SMPs) and microscopic plastic spheres used in cosmetic products and industry (primary MPs; PMPs) are ubiquitously present in the environment. However, despite the fact that most environmental MPs consist of weathered plastic debris with irregular shape and broad size distribution, experimental studies of organism responses to MP exposure have largely used uniformly sized spherical PMPs. Therefore, effects observed for PMPs in such experiments may not be representative for MP-effects in situ. Moreover, invertebrate filter-feeders are generally well adapted to the presence of refractory material in seston, which questions the potential of MPs at environmentally relevant concentrations to measurably affect digestion in these organisms. Here, we compared responses to MPs (PMPs and SMPs) and naturally occurring particles (kaolin clay) using the cladoceran Daphnia magna as a model organism. We manipulated food levels (0.4 and 9 μg C mL-1) and MP or kaolin contribution to the feeding suspension (<1 to 74%) and evaluated effects of MPs and kaolin on food uptake, growth, reproductive capacity of the daphnids, and maternal effects on offspring survival and feeding. Exposure to SMPs caused elevated mortality, increased inter-brood period and decreased reproduction albeit only at high MP levels in the feeding suspension (74% by particle count). No such effects were observed in either PMP or kaolin treatments. In daphnids exposed to any particle type at the low algal concentration, individual growth decreased by ~15%. By contrast, positive growth response to all particle types was observed at the high algal concentration with 17%, 54% and 40% increase for kaolin, PMP and SMP, respectively. When test particles comprised

  11. The Effects of Natural and Anthropogenic Microparticles on Individual Fitness in Daphnia magna.

    PubMed

    Ogonowski, Martin; Schür, Christoph; Jarsén, Åsa; Gorokhova, Elena

    2016-01-01

    Concerns are being raised that microplastic pollution can have detrimental effects on the feeding of aquatic invertebrates, including zooplankton. Both small plastic fragments (microplastics, MPs) produced by degradation of larger plastic waste (secondary MPs; SMPs) and microscopic plastic spheres used in cosmetic products and industry (primary MPs; PMPs) are ubiquitously present in the environment. However, despite the fact that most environmental MPs consist of weathered plastic debris with irregular shape and broad size distribution, experimental studies of organism responses to MP exposure have largely used uniformly sized spherical PMPs. Therefore, effects observed for PMPs in such experiments may not be representative for MP-effects in situ. Moreover, invertebrate filter-feeders are generally well adapted to the presence of refractory material in seston, which questions the potential of MPs at environmentally relevant concentrations to measurably affect digestion in these organisms. Here, we compared responses to MPs (PMPs and SMPs) and naturally occurring particles (kaolin clay) using the cladoceran Daphnia magna as a model organism. We manipulated food levels (0.4 and 9 μg C mL-1) and MP or kaolin contribution to the feeding suspension (<1 to 74%) and evaluated effects of MPs and kaolin on food uptake, growth, reproductive capacity of the daphnids, and maternal effects on offspring survival and feeding. Exposure to SMPs caused elevated mortality, increased inter-brood period and decreased reproduction albeit only at high MP levels in the feeding suspension (74% by particle count). No such effects were observed in either PMP or kaolin treatments. In daphnids exposed to any particle type at the low algal concentration, individual growth decreased by ~15%. By contrast, positive growth response to all particle types was observed at the high algal concentration with 17%, 54% and 40% increase for kaolin, PMP and SMP, respectively. When test particles comprised

  12. Effects of Juvenile Host Density and Food Availability on Adult Immune Response, Parasite Resistance and Virulence in a Daphnia-Parasite System

    PubMed Central

    Schoebel, Corine N.; Auld, Stuart K. J. R.; Spaak, Piet; Little, Tom J.

    2014-01-01

    Host density can increase infection rates and reduce host fitness as increasing population density enhances the risk of becoming infected either through increased encounter rate or because host condition may decline. Conceivably, potential hosts could take high host density as a cue to up-regulate their defence systems. However, as host density usually covaries with food availability, it is difficult to examine the importance of host density in isolation. Thus, we performed two full-factorial experiments that varied juvenile densities of Daphnia magna (a freshwater crustacean) and food availability independently. We also included a simulated high-density treatment, where juvenile experimental animals were kept in filtered media that previously maintained Daphnia at high-density. Upon reaching adulthood, we exposed the Daphnia to their sterilizing bacterial parasite, Pasteuria ramosa, and examined how the juvenile treatments influenced the likelihood and severity of infection (Experiment I) and host immune investment (Experiment II). Neither juvenile density nor food treatments affected the likelihood of infection; however, well-fed hosts that were well-fed as juveniles produced more offspring prior to sterilization than their less well-fed counterparts. By contrast, parasite growth was independent of host juvenile resources or host density. Parasite-exposed hosts had a greater number of circulating haemocytes than controls (i.e., there was a cellular immune response), but the magnitude of immune response was not mediated by food availability or host density. These results suggest that density dependent effects on disease arise primarily through correlated changes in food availability: low food could limit parasitism and potentially curtail epidemics by reducing both the host’s and parasite’s reproduction as both depend on the same food. PMID:24736707

  13. Neverland regulates embryonic moltings through the regulation of ecdysteroid synthesis in the water flea Daphnia magna, and may thus act as a target for chemical disruption of molting.

    PubMed

    Sumiya, Eri; Ogino, Yukiko; Toyota, Kenji; Miyakawa, Hitoshi; Miyagawa, Shinichi; Iguchi, Taisen

    2016-11-01

    Embryo development in arthropods is accompanied by a series of moltings. A cladoceran crustacean Daphnia magna molts three times before reaching first instar neonate during embryogenesis. Previous studies argued ecdysteroids might regulate D. magna embryogenesis. However, no direct evidence between innate ecdysteroids fluctuation and functions has been forthcoming. Recently, we identified genes involved in ecdysteroid synthesis called, neverland (neverland1 and neverland 2) and shade and in the ecdysteroid degradation (Cyp18a1). To understand the physiological roles of ecdysteroids in D. magna embryos, we performed expression and functional analyzes of those genes. Examining innate ecdysteroids titer during embryogenesis showed two surges of ecdysteroids titer at 41 and 61 h after oviposition. The first and second embryonic moltings occurred at each ecdysteroid surge. Expression of neverland1 and shade began to increase before the first peak in ecdysteroid. Knockdown of neverland1 or shade by RNAi technique caused defects in embryonic moltings and subsequent development. The ecdysteroids titer seemingly decreased in nvd1-knowckdown embryos. Knockdown of Cyp18a1 resulted in early embryonic lethality before the first molting. Our in situ hybridization analysis revealed that nvd1 was prominently expressed in embryonic gut epithelium suggesting the site for an initial step of ecdysteroidgenesis, a conversion of cholesterol to 7-dehydrocholesterol and possibly for ecdysone production. Taken together, de novo ecdysteroid synthesis by nvd1 in the gut epithelial cells stimulates molting, which is indispensable for D. magna embryo development. These findings identify neverland as a possible target for chemicals, including various pesticides that are known to disrupt molting, development and reproduction. Copyright © 2016 John Wiley & Sons, Ltd.

  14. An evaluation of aquatic toxicity data with a population growth model for application to environmental hazard assessment. [Ceriodaphnia dubia:a3; Daphnia magna:a3

    SciTech Connect

    Burton, W.D.

    1991-05-01

    Acute and chronic bioassays with the cladocerans Ceriodaphnia dubia and Daphnia magna were conducted using four chemicals, each having a different mode of action. The chemicals were: cadmium (chloride), pentachlorophenol (PCP), 1-octanol, and 1-naphthyl-N-methylcarbamate (carbaryl). The data obtained from the tests were used to compare species sensitivities, endpoint sensitivities, and the relative toxicities of the chemicals. In the acute bioassays, estimates of the median lethal concentrations (48-h LC{sub 50}S) were used to compare the species sensitivities. Ceriodaphnia dubia was more sensitive than D. magna to all four chemicals, and carbaryl was the most toxic chemical to both species. The sensitivity of three endpoints (survival, reproduction and the intrinsic rate of natural increase, r) were used to evaluate the chronic toxicity of the four chemicals to C. dubia and D. magna. Survival, reproduction and r all declined with greater concentrations of the chemicals. These effects were evident in both the 7- or 14-d exposures. The lowest observed effect concentration (LOEC) determined from studies with the four chemicals showed that neither survival nor reproduction was consistently the more sensitive endpoint for either C. dubia or D. magna. The LOECs for r were the same for both exposure durations for each species. The data from this study demonstrate that the calculations of r from chronic toxicity data can provide equally sensitive bioassay results for protecting the environment, while eliminating conflicting interpretations of toxicant effects on separate endpoints. Furthermore, statistical decisions drawn from comparisons of the toxicity of exposure concentrations with the controls may not provide the most ecologically meaningful criteria for environmental protection. 103 refs., 16 figs., 15 tabs.

  15. The Quantification of Representative Sequences pipeline for amplicon sequencing: case study on within-population ITS1 sequence variation in a microparasite infecting Daphnia.

    PubMed

    González-Tortuero, E; Rusek, J; Petrusek, A; Gießler, S; Lyras, D; Grath, S; Castro-Monzón, F; Wolinska, J

    2015-11-01

    Next generation sequencing (NGS) platforms are replacing traditional molecular biology protocols like cloning and Sanger sequencing. However, accuracy of NGS platforms has rarely been measured when quantifying relative frequencies of genotypes or taxa within populations. Here we developed a new bioinformatic pipeline (QRS) that pools similar sequence variants and estimates their frequencies in NGS data sets from populations or communities. We tested whether the estimated frequency of representative sequences, generated by 454 amplicon sequencing, differs significantly from that obtained by Sanger sequencing of cloned PCR products. This was performed by analysing sequence variation of the highly variable first internal transcribed spacer (ITS1) of the ichthyosporean Caullerya mesnili, a microparasite of cladocerans of the genus Daphnia. This analysis also serves as a case example of the usage of this pipeline to study within-population variation. Additionally, a public Illumina data set was used to validate the pipeline on community-level data. Overall, there was a good correspondence in absolute frequencies of C. mesnili ITS1 sequences obtained from Sanger and 454 platforms. Furthermore, analyses of molecular variance (amova) revealed that population structure of C. mesnili differs across lakes and years independently of the sequencing platform. Our results support not only the usefulness of amplicon sequencing data for studies of within-population structure but also the successful application of the QRS pipeline on Illumina-generated data. The QRS pipeline is freely available together with its documentation under GNU Public Licence version 3 at http://code.google.com/p/quantification-representative-sequences.

  16. Making the Most of the "Daphnia" Heart Rate Lab: Optimizing the Use of Ethanol, Nicotine & Caffeine

    ERIC Educational Resources Information Center

    Corotto, Frank; Ceballos, Darrel; Lee, Adam; Vinson, Lindsey

    2010-01-01

    Students commonly test the effects of chemical agents on the heart rate of the crustacean "Daphnia" magna, but the procedure has never been optimized. We determined the effects of three concentrations of ethanol, nicotine, and caffeine and of a control solution on heart rate in "Daphnia." Ethanol at 5% and 10% (v/v) reduced mean heart rate to…

  17. Design and Analysis of Chronic Aquatic Tests of Toxicity with Daphnia magna.

    DTIC Science & Technology

    1981-12-01

    toxicity with Daphnia magna and statistical issues involved in the planning of such tests. All procedures are illustrated with examples based on real...keywords: Daphnia Magna ; Chronic aquatic toxicity tests; Statistical analysis; Graphical data display; Tests of hypothesis; Confidence intervals; Dose

  18. A Simple Temperature Gradient Apparatus To Determine Thermal Preference in "Daphnia."

    ERIC Educational Resources Information Center

    Fenske, Christiane; McCauley, Robert

    2002-01-01

    Explores the dominant factor controlling the distribution of Daphnia. Describes components of a temperature gradient apparatus that can be assembled from materials readily obtainable in the laboratory and hardware stores. Investigates whether the mean depth of Daphnia is determined by temperature. (KHR)

  19. Global proteomic analysis of protein acetylation affecting metabolic regulation in Daphnia pulex.

    PubMed

    Kwon, Oh Kwang; Sim, Juhee; Kim, Sun Ju; Oh, Hye Ryeung; Nam, Doo Hyun; Lee, Sangkyu

    2016-02-01

    Daphnia (Daphnia pulex) is a small planktonic crustacean and a key constituent of aquatic ecosystems. It is generally used as a model organism to study environmental toxic problems. In the past decade, genomic and proteomic datasets of Daphnia have been developed. The proteomic dataset allows for the investigation of toxicological effects in the context of "Daphnia proteomics," resulting in greater insights for toxicological research. To exploit Daphnia for ecotoxicological research, information on the post-translational modification (PTM) of proteins is necessary, as this is a critical regulator of biological processes. Acetylation of lysine (Kac) is a reversible and highly regulated PTM that is associated with diverse biological functions. However, a comprehensive description of Kac in Daphnia is not yet available. To understand the cellular distribution of lysine acetylation in Daphnia, we identified 98 acetylation sites in 65 proteins by immunoprecipitation using an anti-acetyllysine antibody and a liquid chromatography system supported by mass spectroscopy. We identified 28 acetylated sites related to metabolic proteins and six acetylated enzymes associated with the TCA cycle in Daphnia. From GO and KEGG enrichment analyses, we showed that Kac in D. pulex is highly enriched in proteins associated with metabolic processes. Our data provide the first global analysis of Kac in D. pulex and is an important resource for the functional analysis of Kac in this organism.

  20. The effects of the psychiatric drug carbamazepine on freshwater invertebrate communities and ecosystem dynamics.

    PubMed

    Jarvis, Amanda L; Bernot, Melody J; Bernot, Randall J

    2014-10-15

    Freshwater ecosystems are persistently exposed to pharmaceutical pollutants, including carbamazepine. Despite the ubiquity and recalcitrance of carbamazepine, the effects of this pharmaceutical on freshwater ecosystems and communities are unclear. To better understand how carbamazepine influences the invertebrate community and ecosystem dynamics in freshwaters, we conducted a mesocosm experiment utilizing environmentally relevant concentrations of carbamazepine (200 and 2000 ng/L). Mesocosms were populated with four gastropod taxa (Elimia, Physa, Lymnaea and Helisoma), zooplankton, filamentous algae and phytoplankton. After a 31 d experimental duration, structural equation modeling (SEM) was used to relate changes in the community structure and ecosystem dynamics to carbamazepine exposure. Invertebrate diversity increased in the presence of carbamazepine. Additionally, carbamazepine altered the biomass of Helisoma and Elimia, induced a decline in Daphnia pulex abundance and shifted the zooplankton community toward copepod dominance. Lastly, carbamazepine decreased the decomposition of organic matter and indirectly altered primary production and dissolved nutrient concentrations. Changes in the invertebrate community occurred through both direct (i.e., exposure to carbamazepine) and indirect pathways (i.e., changes in food resource availability). These data indicate that carbamazepine may alter freshwater community structure and ecosystem dynamics and could have profound effects on natural systems.

  1. The Reversible Effect of Flow on the Morphology of Ceratocorys Horrida (Peridiniales, Dinophyta)

    DTIC Science & Technology

    2000-01-01

    currents, and boundary effects modifies the physical and chemical environment experienced by planktonic organisms. Vertical transport of phyto- plankton ...formalde- hyde solution, rinsed once in filtered seawater and four times in tapwater, and then freeze-dried on gelatin -coated glass slides. The slides were...MARNIE J. ZIRBEL ET AL. in planktonic freshwater cladocerans such as Daphnia (Brooks 1947, Hrbácek 1959, Havel and Dodson 1985), although the

  2. Acclimatory responses of the Daphnia pulex proteome to environmental changes. I. Chronic exposure to hypoxia affects the oxygen transport system and carbohydrate metabolism

    PubMed Central

    Zeis, Bettina; Lamkemeyer, Tobias; Paul, Rüdiger J; Nunes, Frank; Schwerin, Susanne; Koch, Marita; Schütz, Wolfgang; Madlung, Johannes; Fladerer, Claudia; Pirow, Ralph

    2009-01-01

    Background Freshwater planktonic crustaceans of the genus Daphnia show a remarkable plasticity to cope with environmental changes in oxygen concentration and temperature. One of the key proteins of adaptive gene control in Daphnia pulex under hypoxia is hemoglobin (Hb), which increases in hemolymph concentration by an order of magnitude and shows an enhanced oxygen affinity due to changes in subunit composition. To explore the full spectrum of adaptive protein expression in response to low-oxygen conditions, two-dimensional gel electrophoresis and mass spectrometry were used to analyze the proteome composition of animals acclimated to normoxia (oxygen partial pressure [Po2]: 20 kPa) and hypoxia (Po2: 3 kPa), respectively. Results The comparative proteome analysis showed an up-regulation of more than 50 protein spots under hypoxia. Identification of a major share of these spots revealed acclimatory changes for Hb, glycolytic enzymes (enolase), and enzymes involved in the degradation of storage and structural carbohydrates (e.g. cellubiohydrolase). Proteolytic enzymes remained constitutively expressed on a high level. Conclusion Acclimatory adjustments of the D. pulex proteome to hypoxia included a strong induction of Hb and carbohydrate-degrading enzymes. The scenario of adaptive protein expression under environmental hypoxia can be interpreted as a process to improve oxygen transport and carbohydrate provision for the maintenance of ATP production, even during short episodes of tissue hypoxia requiring support from anaerobic metabolism. PMID:19383146

  3. Filtering capacity of Daphnia magna on sludge particles in treated wastewater.

    PubMed

    Pau, Conxi; Serra, Teresa; Colomer, Jordi; Casamitjana, Xavier; Sala, Lluís; Kampf, Ruud

    2013-01-01

    A great challenge in water reuse is the reduction of suspended particle concentration in wastewater. In particular the reduction of the presence of small particles in suspension which cause a cloudy appearance in the water and, which also make disinfection difficult. The present study evaluates the filtering capacity of a population of Cladodera (Daphnia magna) in secondary effluents from a wastewater plant. The study was performed in both a mesocosm and the laboratory, in an effort to compare the grazing on sludge particles by Daphnia versus the settling rate of those sludge particles. The particle volume concentration of small particles (with a diameter below 30 μm) was used to evaluate the efficiency of the proposed biotreatment system for small particles. Both laboratory and mesocosm results showed that the suspended particle volume concentration decreased with time due to the Daphnia filtration, with the highest reduction in experiments carried out with the highest Daphnia concentration. In the mesocosm experiments, the Daphnia diameter was also found to play an important role, with an allometric relationship between the filtering rate of Daphnia and the Daphnia nondimensional diameter. In laboratory experiments, the effect of D. magna in the suspended concentration of small particles was in the range of 10.1-29.4%, according to the range of Daphnia concentration of 10-50 ind/l. For laboratory experiments, sedimentation was responsible for 62.2% of the suspended particle concentration reduction. For the mesocosm experiments, the reduction in the particle concentration attributed to the Daphnia filtration ranged between 2.5 and 39%, corresponding to Daphnia concentrations of between 5 and 100 ind/l (i.e. biovolumes of 8-60 ind/l).

  4. Acidification of freshwaters

    SciTech Connect

    Cresser, M.S.; Edwards, A.C.

    1987-01-01

    This volume gives an account that draws not only on the main branches of chemistry but also on soil physics, chemistry, hydrology, meteorology, geography, geology, plant physiology, soil microbiology and zoology. The author examine the numerous interacting physical, chemical, and biological, processes that regulate the acidity of freshwaters, a phenomenon that has various causes, including precipitation; acidifying pollutions; and the interaction of plants, soils and water. The relative importance of the different processes is examined.

  5. Pesticide toxicity index for freshwater aquatic organisms, 2nd edition

    USGS Publications Warehouse

    Munn, Mark D.; Gilliom, Robert J.; Moran, Patrick W.; Nowell, Lisa H.

    2006-01-01

    The U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program is designed to assess current water-quality conditions, changes in water quality over time, and the effects of natural and human factors on water quality for the Nation's streams and ground-water resources. For streams, one of the most difficult parts of the assessment is to link chemical conditions to effects on aquatic biota, particularly for pesticides, which tend to occur in streams as complex mixtures with strong seasonal patterns. A Pesticide Toxicity Index (PTI) was developed that combines pesticide exposure of aquatic biota (measured concentrations of pesticides in stream water) with acute toxicity estimates (standard endpoints from laboratory bioassays) to produce a single index value for a sample or site. The development of the PTI was limited to pesticide compounds routinely measured in NAWQA studies and to toxicity data readily available from existing databases. Qualifying toxicity data were found for one or more types of test organisms for 124 of the 185 pesticide compounds measured in NAWQA samples, but with a wide range of available bioassays per compound (1 to 232). In the databases examined, there were a total of 3,669 bioassays for the 124 compounds, including 398 48-hour EC50 values (concentration at which 50 percent of test organisms exhibit a sublethal response) for freshwater cladocerans, 699 96-hour LC50 values (concentration lethal to 50 percent of test organisms) for freshwater benthic invertebrates, and 2,572 96-hour LC50 values for freshwater fish. The PTI for a particular sample is the sum of toxicity quotients (measured concentration divided by the median toxicity concentration from bioassays) for each detected pesticide, and thus, is based on the concentration addition model of pesticide toxicity. The PTI can be calculated for specific groups of pesticides and for specific taxonomic groups. Although the PTI does not determine whether water in a sample is

  6. Effects of ectoine on behavioural, physiological and biochemical parameters of Daphnia magna.

    PubMed

    Bownik, Adam; Stępniewska, Zofia; Skowroński, Tadeusz

    2015-02-01

    Ectoine (ECT) is a compatible solute produced by soil, marine and freshwater bacteria in response to stressful factors. The purpose of our study was to determine the possible toxic influence of ECT on Daphnia magna. We determined the following endpoints: survival rate during exposure and recovery, swimming performance, heart rate, thoracic limb movement determined by image analysis, haemoglobin level by ELISA assay, catalase and nitric oxide species (NOx) by spectrophotometric methods. The results showed 80% survival of daphnids exposed to 50mg/L of ECT after 24h and 10% after 90h, however lower concentrations of ECT were well tolerated. A concentration-dependent reduction of swimming velocity was noted at 24 and 48h of the exposure. ECT (at 2.5 and 4mg/L) induced an increase of heart rate and thoracic limb movement (at 2.5, 4 and 20mg/L) after 24h. After 10h of the exposure to ECT daphnids showed a concentration-dependent increase of haemoglobin level synthesized and accumulated in the epipodite epithelia. After 24h we noted a concentration-dependent decrease of haemoglobin level and its lowest value was found after 48h of the exposure. ECT at a concentration of 20 and 25mg/L slightly stimulated catalase activity after 24h. NOx level was also increased after 10h of the exposure to 20 and 25mg/L of ECT reaching maximal activity after 24h. Our results suggest that ECT possesses some modulatory potential on the behaviour, physiology and biochemical parameters in daphnids.

  7. Ionotropic Glutamate Receptors Mediate Inducible Defense in the Water Flea Daphnia pulex

    PubMed Central

    Miyakawa, Hitoshi; Sato, Masanao; Colbourne, John K.; Iguchi, Taisen

    2015-01-01

    Phenotypic plasticity is the ability held in many organisms to produce different phenotypes with a given genome in response to environmental stimuli, such as temperature, nutrition and various biological interactions. It seems likely that environmental signals induce a variety of mechanistic responses that influence ontogenetic processes. Inducible defenses, in which prey animals alter their morphology, behavior and/or other traits to help protect against direct or latent predation threats, are among the most striking examples of phenotypic plasticity. The freshwater microcrustacean Daphnia pulex forms tooth-like defensive structures, “neckteeth,” in response to chemical cues or signals, referred to as “kairomones,” in this case released from phantom midge larvae, a predator of D. pulex. To identify factors involved in the reception and/or transmission of a kairomone, we used microarray analysis to identify genes up-regulated following a short period of exposure to the midge kairomone. In addition to identifying differentially expressed genes of unknown function, we also found significant up-regulation of genes encoding ionotropic glutamate receptors, which are known to be involved in neurotransmission in many animal species. Specific antagonists of these receptors strongly inhibit the formation of neckteeth in D. pulex, although agonists did not induce neckteeth by themselves, indicating that ionotropic glutamate receptors are necessary but not sufficient for early steps of neckteeth formation in D. pulex. Moreover, using co-exposure of D. pulex to antagonists and juvenile hormone (JH), which physiologically mediates neckteeth formation, we found evidence suggesting that the inhibitory effect of antagonists is not due to direct inhibition of JH synthesis/secretion. Our findings not only provide a candidate molecule required for the inducible defense response in D. pulex, but also will contribute to the understanding of complex mechanisms underlying the

  8. Effects of algal food quality on sexual reproduction of Daphnia magna.

    PubMed

    Choi, Jong-Yun; Kim, Seong-Ki; La, Geung-Hwan; Chang, Kwang-Hyeon; Kim, Dong-Kyun; Jeong, Keon-Young; Park, Min S; Joo, Gea-Jae; Kim, Hyun-Woo; Jeong, Kwang-Seuk

    2016-05-01

    The objective of our study was to investigate sexual reproduction of Daphnia magna associated with mating behaviors and hatching rates, according to different algal food sources. Since a diatom is known to contain more abundant long-chain poly unsaturated fatty acids (PUFAs), we hypothesized that the diatom-consuming D. magna would exhibit more successful reproduction rates. Upon the hypothesis, we designed three experiments using two algal species, a green alga (Chlorella vulgaris) and a diatom (Stephanodiscus hantzschii). From the results, we found that the mating frequency and copulation duration increased in the treatment with S. hantzschii, resulting in a significant increase of hatching rates of resting eggs. In the other two repetitive mating strategies (e.g., one female vs. multiple males, and one male vs. multiple females), we found that the hatching rates of resting eggs were greater in the S. hantzschii treatment. In addition to the mating strategy, male body size significantly increased in the diatom treatment, hence average diameter of penis was also statistically different among the treatments (greater diameter in the S. hantzschii treatment). To examine the effect of algal food quality, we estimated quantity of fatty acids in the two algal species. Our result showed that S. hantzschii had a higher proportion of long-chain PUFAs than C. vulgaris. Furthermore, a stable isotope analysis revealed that carbon and nitrogen originated from S. hantzschii were more assimilated to D. magna. In summary, our study manifested that diatom consumption of D. magna leads to more successful sexual reproduction. We then discussed how the diatom consumption of zooplankton influences food web dynamics in a freshwater ecosystem.

  9. Ecology, Virulence, and Phylogeny of Blastulidium paedophthorum, a Widespread Brood Parasite of Daphnia spp.

    PubMed Central

    James, Timothy Y.; Longworth, Alan

    2015-01-01

    Parasitism is now recognized as a major factor impacting the ecology and evolution of plankton, including Daphnia. Parasites that attack the developing embryos of daphniids, known as brood parasites, were first described in the early 1900s but have received relatively little study. Here, we link previous morphological descriptions of the oomycete brood parasite Blastulidium paedophthorum with information on its phylogenetic placement, ecology, and virulence. Based on the morphology and phylogenetic relationship with other members of the Leptomitales, we show that a brood parasite observed in daphniids in the Midwestern United States is B. paedophthorum. We used morphology, DNA sequences, and laboratory infection experiments to show that B. paedophthorum is a multihost parasite that can be transmitted between species and genera. A field survey of six hosts in 15 lakes revealed that B. paedophthorum is common in all six host taxa (present on 38.3% of our host species-lake-sampling date combinations; the maximum infection prevalences were 8.7% of the population and 20% of the asexual adult female population). Although B. paedophthorum was observed in all 15 lakes, presence and infection prevalence varied among lakes. Infection with B. paedophthorum did not reduce host life span but significantly impacted host fecundity. Theory predicts that parasites that affect host fecundity without affecting host life span should have the strongest impact on host population dynamics. Based on its virulence and commonness in natural populations and on the central role of daphniids in freshwater food webs, we predict that B. paedophthorum will influence daphniid ecology and evolution, as well as the larger food web. PMID:26048938

  10. Reduced cadmium accumulation and toxicity in Daphnia magna under carbon nanotube exposure.

    PubMed

    Liu, Jie; Wang, Wen-Xiong

    2015-12-01

    With increasing application and commercial production, carbon nanotubes (CNTs) will inevitably be released into aquatic environments and affect the transport and toxicity of toxic metals in ecosystems. The present study examined how CNTs affected the biokinetics and toxicity of a toxic metal, cadmium (Cd), in the freshwater zooplankton Daphnia magna. The authors quantified the dissolved uptake and the 50% lethal concentration (LC50, 48 h and 72 h) of Cd in daphnids in the presence of functionalized multiwalled nanotubes (F-CNTs) with different lengths (10-30 µm vs 0.5-2 µm) and concentrations (4 mg/L and 8 mg/L). Compared with the control treatment without CNTs, both CNTs slowed down the accumulation rate of Cd in D. magna over 8 h of exposure and further reduced the accumulation thereafter. Mechanisms for the reduced Cd uptake were mainly related to the influences of CNTs on the physiological activity of daphnids. The LC50 of D. magna in the presence of Cd and shorter CNTs was almost the same as that of the control group without CNTs. However, the LC50 of the groups with normal CNTs was significantly higher than that of the control group (i.e., F-CNTs decreased Cd toxicity significantly). Meanwhile, CNTs also decreased the tolerance of D. magna to Cd. The present study suggests that different physical properties of CNTs, such as length, need to be considered in the environmental risk assessment of CNTs.

  11. Influences of ambient carbon nanotubes on toxic metals accumulation in Daphnia magna.

    PubMed

    Yu, Zhi-Guo; Wang, Wen-Xiong

    2013-08-01

    With the rapid increase of carbon nanotube (CNT) applications, there are considerable concerns of their inevitable releases into the aquatic environments. CNTs may interact with and further influence the fate and transport of other pollutants such as toxic metals. In the present study, non-covalent and nontoxic dispersant polyvinyl pyrrolidone (PVP) was used to provide a relatively stable test solution for CNTs. The dissolved uptake rate constant (ku) and the dietary assimilation efficiency (AE) of cadmium (Cd) and zinc (Zn) were then quantified in a freshwater zooplankton Daphnia magna in the presence of different CNTs (without functionalized - single-walled nanotubes-SWNTs, multi-walled nanotubes-MWNTs, and with functionalized - F-SWNTs, F-MWNTs, containing oxygen functional groups at the defect sites of CNTs) concentrations. We demonstrated that different CNTs exposures led to distinctive metal accumulation patterns. Non-functionalized CNTs significantly decreased the metal uptake rate from the dissolved phase, possibly because of their effects on the physiological activity of animals. In contrast, the F-CNTs (F-SWNTs and F-MWNTs) adsorbed the metals and increased the metal accumulation in daphnids in a concentration-dependent manner, due to the ingestion of F-CNTs associated metals. The AEs of metals in D. magna were elevated by CNTs physical blocking of the animal guts. Our present study showed that CNTs could serve as a new pathway for metal accumulation. This raised a new environmental problem of CNTs since they may induce the accumulation of toxic metals from the dietary exposure.

  12. Alkyl polyglucoside compound influences freshwater plankton community structure in floating field mesocosms.

    PubMed

    Riera, Steven F; Cohen, Risa A

    2016-10-01

    Synthetic surfactants in cleaners and detergents commonly contaminate freshwater systems, therefore use of low-toxicity alternatives is becoming increasingly important. Alkyl polyglucosides (APGs) derived from natural products are less toxic than synthetic surfactants, and degrade rapidly reducing chemical exposure time. However, single species toxicity tests showed APGs have toxic effects on aquatic primary producers and zooplankton, and that species demonstrate different sensitivities to APGs. Furthermore, species unaffected by APGs directly may be indirectly affected by removal of a food source or changes in predator densities, thereby changing plankton community structure. To determine the effects of APGs on plankton communities under environmental conditions, floating mesocosms were deployed in a shallow pond in southeast Georgia, USA and dosed with 0, 0.01, 2.5, 5, or 10 mg L(-1) APG. Zooplankton community composition and abundance, phytoplankton abundance (as chlorophyll a), and water column dissolved oxygen concentration were determined weekly for 1 month. Zooplankton abundance decreased primarily due to loss of copepods, and community composition shifted toward small-bodied cladocerans (Bosmina sp.), and chlorophyll a concentrations declined by up to 81 % following exposure to APG concentrations of 2.5 mg L(-1) or greater. Concentrations of dissolved oxygen never dropped below 5.70 mg L(-1), but the observed declines of ~2 mg L(-1) could become stressful during periods of high water temperatures. Nevertheless, the APG-induced shift from copepod to cladoceran dominated communities and decrease in autochthonous carbon availability has important implications for food availability and quality to higher trophic levels such as planktivorous fishes.

  13. Toxicity of arsenic species to three freshwater organisms and biotransformation of inorganic arsenic by freshwater phytoplankton (Chlorella sp. CE-35).

    PubMed

    Rahman, M Azizur; Hogan, Ben; Duncan, Elliott; Doyle, Christopher; Krassoi, Rick; Rahman, Mohammad Mahmudur; Naidu, Ravi; Lim, Richard P; Maher, William; Hassler, Christel

    2014-08-01

    In the environment, arsenic (As) exists in a number of chemical species, and arsenite (As(III)) and arsenate (As(V)) dominate in freshwater systems. Toxicity of As species to aquatic organisms is complicated by their interaction with chemicals in water such as phosphate that can influence the bioavailability and uptake of As(V). In the present study, the toxicities of As(III), As(V) and dimethylarsinic acid (DMA) to three freshwater organisms representing three phylogenetic groups: a phytoplankton (Chlorella sp. strain CE-35), a floating macrophyte (Lemna disperma) and a cladoceran grazer (Ceriodaphnia cf. dubia), were determined using acute and growth inhibition bioassays (EC₅₀) at a range of total phosphate (TP) concentrations in OECD medium. The EC₅₀ values of As(III), As(V) and DMA were 27 ± 10, 1.15 ± 0.04 and 19 ± 3 mg L(-1) for Chlorella sp. CE-35; 0.57 ± 0.16, 2.3 ± 0.2 and 56 ± 15 mg L(-1) for L. disperma, and 1.58 ± 0.05, 1.72 ± 0.01 and 5.9 ± 0.1 mg L(-1) for C. cf. dubia, respectively. The results showed that As(III) was more toxic than As(V) to L. disperma; however, As(V) was more toxic than As(III) to Chlorella sp. CE-35. The toxicities of As(III) and As(V) to C. cf. dubia were statistically similar (p>0.05). DMA was less toxic than iAs species to L. disperma and C. cf. dubia, but more toxic than As(III) to Chlorella sp. CE-35. The toxicity of As(V) to Chlorella sp. CE-35 and L. disperma decreased with increasing TP concentrations in the growth medium. Phosphate concentrations did not influence the toxicity of As(III) to either organism. Chlorella sp. CE-35 showed the ability to reduce As(V) to As(III), indicating a substantial influence of phytoplankton on As biogeochemistry in freshwater aquatic systems.

  14. Dietary exposure of Daphnia to microcystins: no in vivo relevance of biotransformation.

    PubMed

    Sadler, Thomas; von Elert, Eric

    2014-05-01

    Anthropogenic nutrient input into lakes has contributed to the increased frequency of toxic cyanobacterial blooms. Daphnia populations have been shown to be locally adapted to toxic cyanobacteria and are able to suppress bloom formation; little is known about the physiology behind this phenomenon. Microcystin-LR (MCLR) is the most widespread cyanobacterial toxin, and, based on in vitro experiments, it is assumed that the enzyme glutathione-S-transferase (GST) might act as the first step of detoxification in Daphnia by conjugating MCLR with glutathione. In the present study Daphnia magna was fed a diet of 100% Microcystis aeruginosa PCC7806, a cyanobacterial strain that contains MCLR in high amounts (4.8-5.6 fg cell(-1)), in order to test for a possible conjugation of MCLR with GST in Daphnia in vivo. We used high-resolution LCMS to analyze incubation water, cyanobacterial cells and Daphnia tissue for the presence of MCLR conjugation products as well as unconjugated MCLR. Newly formed conjugation products were detected neither in Daphnia tissue nor in the incubation water. Moreover, the presence of Daphnia led to a decrease in unconjugated MCLR in the cyanobacterial cell fraction due to grazing, in comparison to a control without daphnids, which was well reflected by a similar increase of MCLR in the respective incubation water. As a consequence, the MCLR content did not change due to Daphnia presence within the entire experimental setup. In summary, MCLR ingestion by Daphnia led neither to the formation of conjugation products, nor to a decrease of unconjugated MCLR. GST-mediated conjugation thus seems to be of minor relevance for microcystin (MC) tolerance in Daphnia in vivo. This finding is supported by the fact that GST activity in Daphnia feeding on the MC-containing wildtype or a MC-free mutant of M. aeruginosa PCC7806 revealed an identical increase of specific activity in comparison to a cyanobacteria-free diet. Therefore, the frequently observed induction of

  15. Protective effects of ectoine on heat-stressed Daphnia magna.

    PubMed

    Adam, Bownik; Zofia, Stępniewska; Tadeusz, Skowroński

    2014-12-01

    Ectoine (ECT) is an amino acid produced and accumulated by halophilic bacteria in stressful conditions in order to prevent the loss of water from the cell. There is a lack of knowledge on the effects of ECT in heat-stressed aquatic animals. The purpose of our study was to determine the influence of ECT on Daphnia magna subjected to heat stress with two temperature gradients: 1 and 0.1 °C/min in the range of 23-42 °C. Time to immobilisation, survival during recovery, swimming performance, heart rate, thoracic limb movement and the levels of heat shock protein 70 kDa 1A (HSP70 1A), catalase (CAT) and nitric oxide species (NOx) were determined in ECT-exposed and unexposed daphnids; we showed protective effects of ECT on Daphnia magna subjected to heat stress. Time to immobilisation of daphnids exposed to ECT was longer when compared to the unexposed animals. Also, survival rate during the recovery of daphnids previously treated with ECT was higher. ECT significantly attenuated a rapid increase of mean swimming velocity which was elevated in the unexposed daphnids. Moreover, we observed elevation of thoracic limb movement and modulation of heart rate in ECT-exposed animals. HSP70 1A and CAT levels were reduced in the presence of ECT. On the other hand, NOx level was slightly elevated in both ECT-treated and unexposed daphnids, however slightly higher NOx level was found in ECT-treated animals. We conclude that the exposure to ectoine has thermoprotective effects on Daphnia magna, however their mechanisms are not associated with the induction of HSP70 1A.

  16. Optimisation of DNA extraction from the crustacean Daphnia

    PubMed Central

    Athanasio, Camila Gonçalves; Chipman, James K.; Viant, Mark R.

    2016-01-01

    Daphnia are key model organisms for mechanistic studies of phenotypic plasticity, adaptation and microevolution, which have led to an increasing demand for genomics resources. A key step in any genomics analysis, such as high-throughput sequencing, is the availability of sufficient and high quality DNA. Although commercial kits exist to extract genomic DNA from several species, preparation of high quality DNA from Daphnia spp. and other chitinous species can be challenging. Here, we optimise methods for tissue homogenisation, DNA extraction and quantification customised for different downstream analyses (e.g., LC-MS/MS, Hiseq, mate pair sequencing or Nanopore). We demonstrate that if Daphnia magna are homogenised as whole animals (including the carapace), absorbance-based DNA quantification methods significantly over-estimate the amount of DNA, resulting in using insufficient starting material for experiments, such as preparation of sequencing libraries. This is attributed to the high refractive index of chitin in Daphnia’s carapace at 260 nm. Therefore, unless the carapace is removed by overnight proteinase digestion, the extracted DNA should be quantified with fluorescence-based methods. However, overnight proteinase digestion will result in partial fragmentation of DNA therefore the prepared DNA is not suitable for downstream methods that require high molecular weight DNA, such as PacBio, mate pair sequencing and Nanopore. In conclusion, we found that the MasterPure DNA purification kit, coupled with grinding of frozen tissue, is the best method for extraction of high molecular weight DNA as long as the extracted DNA is quantified with fluorescence-based methods. This method generated high yield and high molecular weight DNA (3.10 ± 0.63 ng/µg dry mass, fragments >60 kb), free of organic contaminants (phenol, chloroform) and is suitable for large number of downstream analyses. PMID:27190714

  17. Statistical validation of structured population models for Daphnia magna.

    PubMed

    Adoteye, Kaska; Banks, H T; Cross, Karissa; Eytcheson, Stephanie; Flores, Kevin B; LeBlanc, Gerald A; Nguyen, Timothy; Ross, Chelsea; Smith, Emmaline; Stemkovski, Michael; Stokely, Sarah

    2015-08-01

    In this study we use statistical validation techniques to verify density-dependent mechanisms hypothesized for populations of Daphnia magna. We develop structured population models that exemplify specific mechanisms and use multi-scale experimental data in order to test their importance. We show that fecundity and survival rates are affected by both time-varying density-independent factors, such as age, and density-dependent factors, such as competition. We perform uncertainty analysis and show that our parameters are estimated with a high degree of confidence. Furthermore, we perform a sensitivity analysis to understand how changes in fecundity and survival rates affect population size and age-structure.

  18. Morphological and ultrastructural effects of sublethal cadmium poisoning on Daphnia

    SciTech Connect

    Griffiths, P.R.E.

    1980-08-01

    When Daphnia magna were exposed to 52 and 12 ..mu..g Cd/sup 2 +/ liter/sup -1/ their gut diverticula became shrunken, empty of chlorophyll, and paralyzed. This effect is easily observed in living animals and might serve as a useful indicator of low levels of cadmium pollution in the field. Electron microscope studies revealed the formation of granules of calcium on the basal and lateral cell membranes and also in the mitochondria and microvilli of the cells of these distorted organs.

  19. Small scale mass culture of Daphnia magna Straus

    SciTech Connect

    Rees, J.T.; Oldfather, J.M.

    1980-02-01

    Daphnia magna Straus 1820 was raised on a defined medium in 4-liter flasks with controlled light intensity, temperature, and algal food species. Adult D. magna tolerated high levels of ammonia (up to 108 ..mu..M) at high pH (> 10), although at these levels parthenogenic reproduction may be inhibited. Scenedesmus quadricauda and Ankistrodesmus sp. were satisfactory food sources, and by utilizing Ankistrodesmus densities greater than one animal per ml were achieved. Maintaining the pH at about 7 to 8 seems to be important for successful D. magna culture.

  20. Effects of metal salt mixtures on Daphnia magna reproduction

    SciTech Connect

    Biesinger, K.E.; Christensen, G.M.; Fiandt, J.T.

    1986-02-01

    Three binary metal experiments were conducted using a complete block design; testing the chlorides of Cd, Hg, and Zn individually and in combinations of Cd-Hg, Cd-Zn, and Zn-Hg on Daphnia magna reproduction. These mixtures were tested at one-half, once, and twice the 16% reproductive impairment concentration previously determined for individual metals. The Cd-Hg, Cd-Zn, and Zn-Hg mixtures all showed significant reductions in reproduction at concentrations where the metal salts alone caused no significant effect.

  1. Effects of pollution on freshwater organisms

    SciTech Connect

    Phipps, G.L.; Harden, M.J.; Leonard, E.N.; Roush, T.H; Spehar, D.L.; Stephan, C.E.; Pickering, Q.H.; Buikema, A.L. Jr.

    1984-06-01

    This review includes subjects in last year's reviews on effects of pollution on freshwater invertebrates and effects of pollution on freshwater fish and amphibians. This review also includes information on the effects of pollution on freshwater plants. 625 references.

  2. Hybridization and the Origin of Contagious Asexuality in Daphnia pulex

    PubMed Central

    Xu, Sen; Spitze, Ken; Ackerman, Matthew S.; Ye, Zhiqiang; Bright, Lydia; Keith, Nathan; Jackson, Craig E.; Shaw, Joseph R.; Lynch, Michael

    2015-01-01

    Hybridization plays a potentially important role in the origin of obligate parthenogenesis (OP) in many organisms. However, it remains controversial whether hybridization directly triggers the transition from sexual reproduction to obligate asexuality or a hybrid genetic background enables asexual species to persist. Furthermore, we know little about the specific genetic elements from the divergent, yet still hybridizing lineages responsible for this transition and how these elements are further spread to create other OP lineages. In this study, we address these questions in Daphnia pulex, where cyclically parthenogenetic (CP) and OP lineages coexist. Ancestry estimates and whole-genome association mapping using 32 OP isolates suggest that a complex hybridization history between the parental species D. pulex and D. pulicaria is responsible for the introgression of a set of 647 D. pulicaria single nucleotide polymorphism alleles that show perfect association with OP. Crossing experiments using males of OP lineages and females of CP lineages strongly support a polygenic basis for OP. Single-sperm analyses show that although normal meiotic recombination occurs in the production of haploid sperm by males of OP lineages, a significant proportion of such sperm are polyploid, suggesting that the spread of asexual elements through these males (i.e., contagious asexuality) is much less efficient than previously envisioned. Although the current Daphnia genome annotation does not provide mechanistic insight into the nature of the asexuality-associated alleles, these alleles should be considered as candidates for future investigations on the genetic underpinnings of OP. PMID:26351296

  3. Bioconcentration of organic contaminants in Daphnia resting eggs.

    PubMed

    Chiaia-Hernandez, Aurea C; Ashauer, Roman; Moest, Markus; Hollingshaus, Tobias; Jeon, Junho; Spaak, Piet; Hollender, Juliane

    2013-09-17

    Organic contaminants detected in sediments from Lake Greifensee and other compounds falling in the log Dow range from 1 to 7 were selected to study the bioconcentration of organic contaminants in sediments in Daphnia resting eggs (ephippia). Our results show that octocrylene, tonalide, triclocarban, and other personal care products, along with pesticides and biocides can accumulate in ephippia with log BCF values up to 3. Data on the uptake and depuration kinetics show a better fit toward a two compartment organism model over a single compartment model due to the differences in ephippial egg content in the environment. The obtained BCFs correlate with hydrophobicity for neutral compounds. Independence between BCF and hydrophobicity was observed for partially ionized compounds with log Dow values around 1. Internal concentrations in ephippia in the environment were predicted based on sediment concentrations using the equilibrium partitioning model and calculated BCFs. Estimated internal concentration values ranged between 1 and 68,000 μg/kglip with triclocarban having the highest internal concentrations followed by tonalide and triclosan. The outcomes indicate that contaminants can be taken up by ephippia from the water column or the pore water in the sediment and might influence fitness and sexual reproduction in the aquatic key species of the genus Daphnia.

  4. Quaternary diversification in a sexual Holarctic zooplankter, Daphnia galeata.

    PubMed

    Ishida, Seiji; Taylor, Derek J

    2007-02-01

    The effects of Quaternary glacial range partitioning on the diversification of Holarctic biota remain unclear. Glacial refugial lineages may form vicariant species, hybrid products, or merge after secondary contact. Here, we assess the effects of Quaternary glaciation on a Holarctic sexual zooplankter, Daphnia galeata, with apparently marked dispersal capacity and a widespread hybrid lineage in the New World. We collected samples of this species from 148 Holarctic lakes, analysed the nuclear and mitochondrial gene sequences, and tested predictions for hypotheses that account for the origin and spread of the New World D. galeata. We detected five nuclear phylogroups and four mitochondrial phylogroups, most of which were restricted to either the New World or the Old World. The oldest mitochondrial phylogroup was restricted to Japan. One major mitochondrial clade was distributed throughout the Holarctic, but only four haplotypes were shared among continents, and analysis of molecular variance indicated significant structure at the continental level. Haplotype sharing among continents could largely be attributed to anthropogenic introductions. Mismatch distributions, haplotype networks, phylogenetic trees, longitudinal haplotype diversity erosion and coalescence analyses are consistent with colonization from an Old World and a New World refugium. Our nuclear and mitochondrial DNA sequence evidence supports the hypothesis that the New World D. galeata underwent introgression with Daphnia dentifera, with dispersal being enhanced by glaciation. We conclude that Quaternary glaciation had a pronounced effect on the diversification of a Holarctic sexual zooplankter.

  5. Multigenerational genomic responses to dietary phosphorus and temperature in Daphnia.

    PubMed

    Jalal, Marwa; Shala, Nita K; Wojewodzic, Marcin W; Andersen, Tom; Hessen, Dag O

    2014-08-01

    Temperature and nutrient availability are both hypothesized to affect organisms at the cellular and genomic levels. In this multigenerational study, Daphnia magna (D. magna) and Daphnia pulex (D. pulex) were maintained at high (20 °C) and low (10 °C) temperatures and nourished with phosphorus (P)-sufficient (50 μmol/L) and P-deficient (2 μmol/L) algae for up to 35 generations to assess the multigenerational impacts on genome size and nucleus size. Analysis by flow cytometry revealed significant increases in nucleus size for both species as well as genome size for D. magna in response to a low temperature. The degree of endoreplication, measured as cycle value, was species specific and responded to temperature and dietary composition. Under dietary P deficiency, D. magna, but not D. pulex, showed an apparent reduction in haploid genome size (C-value). These genomic responses are unlikely to reflect differences in nucleotide numbers, but rather structural changes affecting fluorochrome binding. While the ultimate and proximate causes of these responses are unknown, they suggest an intriguing potential for genomic responses that merits further research.

  6. Copper complexation and toxicity to Daphnia in natural waters

    SciTech Connect

    Borgmann, U.; Charlton, C.C.

    1984-01-01

    Toxicity of copper to Daphnia magna in artificial medium, artificial medium plus algae, and natural water from Hamilton Harbour and Lake Ontario was determined, with and without added Tris, in order to test the assumption that free cupric ion concentrations are the same in equivalently toxic media even when total copper concentrations vary. Free cupric ion concentrations were calculated from the increase in the total copper concentration tolerated after Tris addition and from cupric ion electrode measurements. Copper toxicity was greatest in inorganic medium, lowest in inorganic medium plus algae and in Hamilton Harbour water, and intermediate in lake water. However, after Tris addition, toxicity was greatest in lake water and lowest in inorganic medium and inorganic medium plus algae. Both the bioassay and electrode data indicate that free cupric ion concentrations differ in different test waters when toxicity is the same. Free metal concentrations do not, therefore, provide a good measure of copper toxicity for Daphnia in natural waters. 12 references, 1 figure, 1 table.

  7. Juvenile hormone agonists affect the occurrence of male Daphnia.

    PubMed

    Tatarazako, Norihisa; Oda, Shigeto; Watanabe, Hajime; Morita, Masatoshi; Iguchi, Taisen

    2003-12-01

    The water flea Daphnia magna reproduces primarily by cyclic parthenogenesis. Environmental stimuli that signal a change to adverse conditions induce the organisms to switch from parthenogenesis to gamogenetic reproduction. During the gamogenetic period, they produce male daphnids and dormant resting eggs, which can survive prolonged periods of environmental adversity. However, little is known about the mechanisms associated with the switch from parthenogenesis to gamogenetic reproduction. We investigated the effects of several juvenoids on sex determination in Daphnia. Females less than 24 h old were exposed to various concentrations of the test substance and were observed for 21 days. It was found that they can trigger the appearance of male daphnids: the percentage of males in the population increases to a level greater than what occurs under ordinary environmental conditions. We found that methylfarnesoate, juvenile hormone III, methoprene, and the phenoxyphenoxy derivatives pyriproxyfen and fenoxycarb (both insecticides) reduced the production of offspring and produced sex ratios dominated by male daphnids. Pyriproxyfen and fenoxycarb showed striking effects at low concentrations. Exposure to either of these chemicals at a concentration of 330 ngl(-1) caused adult females to produce almost all male neonates. Methylfarnesoate, juvenile hormone III, and methoprene showed an effect in inducing male production at higher concentrations (3.7 x 10(3), 3.3 x 10(5), and 1.3 x 10(5) ngl(-1), respectively). Our findings suggest that juvenile hormone agonists, including some insecticides, affect the chemical signaling responsible for inducing the production of male offspring.

  8. Characterization of newly gained introns in Daphnia populations.

    PubMed

    Li, Wenli; Kuzoff, Robert; Wong, Chen Khuan; Tucker, Abraham; Lynch, Michael

    2014-08-14

    As one of the few known species in an active phase of intron proliferation, the microcrustacean Daphnia pulex is an especially attractive system for interrogating the gain and loss of introns in natural populations. In this study, we used a comparative population-genomic approach to identify and characterize 90 recently gained introns in this species. Molecular clock analyses indicate that these introns arose between 3.9 × 10(5) and 1.45 × 10(4) years ago, with a spike in intron proliferation approximately 5.2 × 10(4) to 1.22 × 10(5) years ago. Parallel gains at homologous positions contribute to 47.8% (43/90) of discovered new introns. A disproportionally large number of new introns were found in historically isolated populations in Oregon. Nonetheless, derived, intron-bearing alleles were also identified in a wide range of geographic locations, suggesting intron gain and, to a lesser degree, intron loss are important sources of genetic variation in natural populations of Daphnia. A majority (55/90 or 61.1%) of the identified neointrons have associated internal direct repeats with lengths and compositions that are unlikely to occur by chance, suggesting repeated bouts of staggered double-strand breaks (DSBs) during their evolution. Accordingly, internal, staggered DSBs may contribute to a passive trend toward increased length and sequence diversity in nascent introns.

  9. Short-term exposure with high concentrations of pristine microplastic particles leads to immobilisation of Daphnia magna.

    PubMed

    Rehse, Saskia; Kloas, Werner; Zarfl, Christiane

    2016-06-01

    Recent studies revealed that freshwaters are not only polluted by chemicals, but also by persistent synthetic material like microplastics (plastic particles <1 mm). Microplastics include a diverse range of characteristics, e.g. polymer type, size or shape, but also their tendency to sorb pollutants or release additives. Although there is rising concern about the pollution of freshwaters by microplastics, knowledge about their potential effects on organisms is limited. For a better understanding of their risks, it is crucial to unravel which characteristics influence their effects on organisms. Analysing effects by the mere particles is the first step before including more complex interactions e.g. with associated chemicals. The aim of this study was to analyse potential physical effects of microplastics on one representative organism for limnic zooplankton (Daphnia magna). We investigated whether microplastics can be ingested and whether their presence causes adverse effects after short-term exposure. Daphnids were exposed for up to 96 h to 1-μm and 100-μm polyethylene particles at concentrations between 12.5 and 400 mg L(-1). Ingestion of 1-μm particles led to immobilisation increasing with dose and time with an EC50 of 57.43 mg L(-1) after 96 h. 100-μm particles that could not be ingested by the daphnids had no observable effects. These results underline that, considering high concentrations, microplastic particles can already induce adverse effects in limnic zooplankton. Although it needs to be clarified if these concentrations can be found in the environment these results are a basis for future impact analysis, especially in combination with associated chemicals.

  10. Sperm in "parhenogenetic" freshwater gastrotrichs.

    PubMed

    Weiss, M J; Levy, D P

    1979-07-20

    Freshwater members of the phylum Gastrotricha have been considered obligate parthenogens. In Lepidodermelia squammata, the species for which there is most evidence for parthenogenesis, sperm have been discovered. This finding will necessitate reexamination of the nature of sexuality and life cycles and of the concept of "species" in freshwater gastrotrichs.

  11. Toxicity of exposure to binary mixtures of four anti-neoplastic drugs in Daphnia magna and Ceriodaphnia dubia.

    PubMed

    Parrella, Alfredo; Kundi, Michael; Lavorgna, Margherita; Criscuolo, Emma; Russo, Chiara; Isidori, Marina

    2014-12-01

    Anticancer drugs, interfering with DNA in every living organism, may pose a threat to aquatic environment, even more when they occur as complex mixtures. We investigated the combined long term toxic potential of four anti-neoplastic drugs (5-fluorouracil [5-FU], cisplatin [CDDP], etoposide [ET] and imatinib mesylate [IM]) testing their binary mixtures on two primary consumers of the freshwater aquatic chain with close phylogenetic relationship: Daphnia magna and Ceriodaphnia dubia. The combined toxicities were assessed using two distinct effect sizes that should be observed if Bliss independence holds. Direct statistical comparison by analysis of variance of single and combined toxicities under the assumption of Bliss independence allowed to accept or reject the independency hypothesis. Independency was confirmed for all mixtures both in D. magna and in C. dubia, except for IM+ ET and IM+CDDP in D. magna and for ET+CDDP and ET+5-FU in C. dubia which at the highest concentrations showed an antagonistic interaction. A synergic tendency was found testing IM+CDDP on C. dubia at the lowest concentration selected. Thus, the chronic ecotoxicological data evaluated in this study show not only a potential environmental risk of anticancer drugs, especially considering their potential synergistic effects, but also the necessity to integrate statistical models with experimental data to establish the real environmental impact of such compounds.

  12. Optimal conditions for three brood chronic toxicity test method using a freshwater macroinvertebrate Moina macrocopa.

    PubMed

    Oh, Sorin; Choi, Kyungho

    2012-06-01

    Freshwater cladocera such as Daphnia magna and Ceriodaphnia dubia have been used extensively for freshwater toxicity test worldwide. However, these species may not be indigenous in certain geographical regions, which restrict the utility of these organisms as test species. In the present study, we investigated optimal culture and test conditions for an indigenous freshwater macroinvertebrate of Korea, Moina macrocopa. The culture conditions that were evaluated included water temperature (20°C and 25°C), rearing media (moderately hard water or MHW, with or without selenium supplementation, or Elendt M4), and food density (2.5 × 10(7) and 5 × 10(7) cells/mL of Selenastrum capricornutum), and their effects on the life history characteristics of M. macrocopa were determined. Population growth rate of M. macrocopa was maximized at 25°C with 5 × 10(7) cells/mL of algal food density in MHW. A series of chronic three brood reference toxicant tests were conducted under the ideal culture conditions that were identified here, and the results of the tests indicated reliable reproducibility of the test protocol. Optimal culture and test conditions that were identified for M. macrocopa in the present study are suggested for evaluation of chronic toxicity of chemicals and industrial or municipal discharge.

  13. Toxicities of 48 pharmaceuticals and their freshwater and marine environmental assessment in northwestern France.

    PubMed

    Minguez, Laetitia; Pedelucq, Julie; Farcy, Emilie; Ballandonne, Céline; Budzinski, Hélène; Halm-Lemeille, Marie-Pierre

    2016-03-01

    A risk assessment for freshwater and marine ecosystems is presented for 48 pharmaceutical compounds, belonging to 16 therapeutic classes, and prescribed in northwestern France. Ecotoxicity data were obtained on two freshwater organisms, i.e., crustacean Daphnia magna and the green algae Pseudokirchneriella subcapitata, and on two marine organisms, i.e., the crustacean Artemia salina and the diatom Skeletonema marinoi. Measured environmental concentrations (MEC), in the Orne River and sea off Merville-Franceville in the Basse-Normandie region, were compared to the predicted environmental concentrations (PEC). Predicted no-effect concentrations (PNEC) were derived from acute data for each compound. Then, a risk assessment for each compound and the mixture was performed by calculating risk quotients (RQ as PEC or MEC/PNEC ratio). Results showed that no immediate acute toxicities were expected even if some compounds displayed strong toxicities at very low concentrations. Antibiotics, antidepressants, and antifungals would deserve attention because of their high or median ecological risk suspected on marine and freshwater ecosystems. Marine ecosystems would be more sensitive to pharmaceutical residues.

  14. GROWTH, SURVIVORSHIP, AND REPRODUCTION OF DAPHNIA MIDDENDORFFIANA IN SEVERAL ARCTIC LAKES AND PONDS

    EPA Science Inventory

    The growth, survivorship and reproduction of Arctic region Daphnia middendorffiana was investigated in several lakes and ponds on the tundra in northern Alaska and additionally in a laboratory study. Growth rate equations, reproduction rates and survivorship under natural conditi...

  15. Accumulation and inactivation of avian influenza virus by the filter-feeding invertebrate Daphnia magna.

    PubMed

    Meixell, Brandt W; Borchardt, Mark A; Spencer, Susan K

    2013-12-01

    The principal mode of avian influenza A virus (AIV) transmission among wild birds is thought to occur via an indirect fecal-oral route, whereby individuals are exposed to virus from the environment through contact with virus-contaminated water. AIV can remain viable for an extended time in water; however, little is known regarding the influence of the biotic community (i.e., aquatic invertebrates) on virus persistence and infectivity in aquatic environments. We conducted laboratory experiments to investigate the ability of an aquatic filter-feeding invertebrate, Daphnia magna, to accumulate virus from AIV-dosed water under the hypothesis that they represent a potential vector of AIV to waterfowl hosts. We placed live daphnids in test tubes dosed with low-pathogenicity AIV (H3N8 subtype isolated from a wild duck) and sampled Daphnia tissue and the surrounding water using reverse transcription-quantitative PCR (RT-qPCR) at 3- to 120-min intervals for up to 960 min following dosing. Concentrations of viral RNA averaged 3 times higher in Daphnia tissue than the surrounding water shortly after viral exposure, but concentrations decreased exponentially through time for both. Extracts from Daphnia tissue were negative for AIV by cell culture, whereas AIV remained viable in water without Daphnia present. Our results suggest daphnids can accumulate AIV RNA and effectively remove virus particles from water. Although concentrations of viral RNA were consistently higher in Daphnia tissue than the water, additional research is needed on the time scale of AIV inactivation after Daphnia ingestion to fully elucidate Daphnia's role as a potential vector of AIV infection to aquatic birds.

  16. Accumulation and Inactivation of Avian Influenza Virus by the Filter-Feeding Invertebrate Daphnia magna

    PubMed Central

    Borchardt, Mark A.; Spencer, Susan K.

    2013-01-01

    The principal mode of avian influenza A virus (AIV) transmission among wild birds is thought to occur via an indirect fecal-oral route, whereby individuals are exposed to virus from the environment through contact with virus-contaminated water. AIV can remain viable for an extended time in water; however, little is known regarding the influence of the biotic community (i.e., aquatic invertebrates) on virus persistence and infectivity in aquatic environments. We conducted laboratory experiments to investigate the ability of an aquatic filter-feeding invertebrate, Daphnia magna, to accumulate virus from AIV-dosed water under the hypothesis that they represent a potential vector of AIV to waterfowl hosts. We placed live daphnids in test tubes dosed with low-pathogenicity AIV (H3N8 subtype isolated from a wild duck) and sampled Daphnia tissue and the surrounding water using reverse transcription-quantitative PCR (RT-qPCR) at 3- to 120-min intervals for up to 960 min following dosing. Concentrations of viral RNA averaged 3 times higher in Daphnia tissue than the surrounding water shortly after viral exposure, but concentrations decreased exponentially through time for both. Extracts from Daphnia tissue were negative for AIV by cell culture, whereas AIV remained viable in water without Daphnia present. Our results suggest daphnids can accumulate AIV RNA and effectively remove virus particles from water. Although concentrations of viral RNA were consistently higher in Daphnia tissue than the water, additional research is needed on the time scale of AIV inactivation after Daphnia ingestion to fully elucidate Daphnia's role as a potential vector of AIV infection to aquatic birds. PMID:24038705

  17. Acute toxicity of furazolidone on Artemia salina, Daphnia magna, and Culex pipiens molestus larvae

    SciTech Connect

    Macri, A.; Stazi, A.V.; Dojmi di Delupis, G.

    1988-10-01

    As a result of evidence of the ecotoxicity of nitrofurans, the acute toxicity of furazolidone was tested in vivo on two aquatic organisms, Artemia salina and Daphnia magna, which are both crustaceans. Toxicity studies were also performed on larvae of Culex pipiens molestus. Results indicated a significant toxicity of the compound on Culex pipiens and Daphnia magna, while Artemia salina proved to be the least sensitive.

  18. Acute toxic effects of two lampricides on twenty-one freshwater invertebrates

    USGS Publications Warehouse

    Rye, Robert P.; King, Everett Louis

    1976-01-01

    We conducted laboratory static bioassays to determine acute toxicity of two lampricides -- a 70% 2-aminoethanol salt of 5,2'dichloro-4'-nitrosalicylanilide (Bayer 73) and a mixture containing 98% 3-trifluoromethyl-4-nitrophenol (TFM) and 2% Bayer 73 (TFM-2B) -- to 21 freshwater invertebrates. LC50 values were determined for 24-h exposure periods at 12.8 C. Organisms relatively sensitive to Bayer 73 were a turbellarian (Dugesia tigrina), aquatic earthworms (Tubifex tubifex and Lumbriculus inconstans), snails (Physa sp.) and (Pleurocera sp.), a clam (Eliptio dilatatus), blackflies (Simulium sp.), leeches (Erpobdellidae), and a daphnid (Daphnia pulex). The invertebrates most sensitive to TFM-2B were turbellarians, aquatic earthworms (Tubifex), snails (Physa), blackflies, leeches, and burrowing mayflies (Hexagenia sp.). Bayer 73 was generally much more toxic to the test organisms than TFM-2B. At lampricidal concentrations, TFM-2B was more highly selective than Bayer 73 against larval sea lampreys (Petromyzon marinus).

  19. Derivation and selection of freshwater sediment quality values in Washington state

    SciTech Connect

    Cubbage, J.; Breidenbach, S.; Batts, D.

    1995-12-31

    To derive chemical-based Freshwater Sediment Quality Values (FSQV), bioassay data (Hyalella azteca, Microtox, Chironomus tentans, Daphnia magna, Ceriodaphnia dubia, and Hexagenia limbata) and chemistry data (metals, PAH, pesticide/PCBs, and phenols) were merged from 33 studies and 245 sites in Washington and Oregon into a single database. Apparent Effects Thresholds (AET) and Probable AETs (PAET: 95th percentile of no effects sites) were calculated for Hyalella azteca (n = 228) and Microtox. The efficiency and sensitivity of these values in predicting biological response from chemical concentrations were compared with Ontario`s Severe Effects Level (SEL), Environment Canada`s Probable Effects Level (PEL) and Threshold Effects Level (TEL), EPA`s Equilibrium Partitioning (EQP), and Washington`s marine Sediment management Standards (SMS). For PAH, dry weight normalized values for AETs and PAETs were significantly more sensitive and efficient than organic carbon normalized values. TEL was always the most sensitive and least efficient.

  20. Effects of common-use pesticides on developmental and reproductive processes in Daphnia.

    PubMed

    Kashian, Donna R; Dodson, Stanley I

    2002-06-01

    Daphnia magna were evaluated for use as a screen for pesticides that have been demonstrated to have estrogenic (o'p'-DDT, di-n-butyl phthalate, toxaphene), anti-androgenic (p'p-DDE, linuron), thyroid (acetochlor, alachlor, metribuzin), insulin (amitraz) or lutenizing hormone (2,4-D) activity in vertebrates, and to establish daphnid sensitivity to these compounds. Pesticides with unknown effects on vertebrate endocrine systems (chlorosulfuran, cyanazine, diflubenzuron, metolachlor, and diquat) were also evaluated. Compounds were assayed for six days at environmentally relevant concentrations ranging from 0.001 to 100 mirog/L, using female Daphnia and their offspring. Sublethal endpoints included offspring sex (sex determination), clutch size (fecundity), and adult size (growth rate). Toxaphene was the only compound that affected sexual differentiation, increasing male production. Daphnia fecundity declined with exposure to toxaphene, and daphnid growth rates were reduced by acetochlor exposure. Diflubenzuron, o'p'-DDT, and p'p-DDE significantly reduced Daphnia survival. No correlation existed between affected reproductive or developmental processes and specific endocrine systems or subsystems. Results from this study indicate that Daphnia make a good screen for assessing potential environmental impacts but are not a useful indicator of pesticide hormonal activity in vertebrates. This assay consistently detected sublethal but ecologically relevant effects of these pesticides on Daphnia at environmentally relevant concentrations typically below their listed EC50 value.

  1. Conserved transcriptional responses to cyanobacterial stressors are mediated by alternate regulation of paralogous genes in Daphnia.

    PubMed

    Asselman, Jana; Pfrender, Michael E; Lopez, Jacqueline A; De Coninck, Dieter I M; Janssen, Colin R; Shaw, Joseph R; De Schamphelaere, Karel A C

    2015-04-01

    Despite a significant increase in genomic data, our knowledge of gene functions and their transcriptional responses to environmental stimuli remains limited. Here, we use the model keystone species Daphnia pulex to study environmental responses of genes in the context of their gene family history to better understand the relationship between genome structure and gene function in response to environmental stimuli. Daphnia were exposed to five different treatments, each consisting of a diet supplemented with one of five cyanobacterial species, and a control treatment consisting of a diet of only green algae. Differential gene expression profiles of Daphnia exposed to each of these five cyanobacterial species showed that genes with known functions are more likely to be shared by different expression profiles, whereas genes specific to the lineage of Daphnia are more likely to be unique to a given expression profile. Furthermore, while only a small number of nonlineage-specific genes were conserved across treatment type, there was a high degree of overlap in expression profiles at the functional level. The conservation of functional responses across the different cyanobacterial treatments can be attributed to the treatment-specific expression of different paralogous genes within the same gene family. Comparison with available gene expression data in the literature suggests differences in nutritional composition in diets with cyanobacterial species compared to diets of green algae as a primary driver for cyanobacterial effects on Daphnia. We conclude that conserved functional responses in Daphnia across different cyanobacterial treatments are mediated through alternate regulation of paralogous gene families.

  2. Effects of He-Ne laser on Daphnia magna Straus manifested in subsequent generations

    NASA Astrophysics Data System (ADS)

    Vorob'yeva, O. V.; Filenko, O. F.; Isakova, E. F.; Vorobieva, N. N.; Rybaltovskii, A. O.; Yusupov, V. I.; Bagratashvili, V. N.

    2015-11-01

    The effects of He-Ne laser irradiation (including visible laser light 632.8 nm in wavelength and an attendant electromagnetic field from the laser apparatus) on the fertility, newborn quality and linear dimensions of the body of Cladocera Daphnia magna Straus were determined. It is shown that the attendant electromagnetic field generated by the laser apparatus can have significant impact on the results of low-intensity laser therapy. The laser light exposure of daphnia to a dose range of 1.7-1300 mJ cm-2 stimulates the integral functions of the daphnia’s body. At the same time, the attendant electromagnetic field (72 mA m-1 in the frequency range of 0.02-20 kHz and 400 mA m-1 in the frequency range of 3-4 MHz) causes the appearance of quickly dying and/or abnormal newborn (up to a small percent) that has never been observed in the control. Anomalies of daphnia mainly consisted of swimming antenna pathologies. Moreover, under the influence of the attendant electromagnetic field on parental daphnia only, these anomalies appear even in several subsequent generations of newborn. The negative impact on daphnia disappears completely after the suppression of the attendant electromagnetic field to laboratory background level. It is shown that laser light can partially compensate the negative impact of the attendant electromagnetic field on Daphnia.

  3. Demands of eicosapentaenoic acid (EPA) in Daphnia: are they dependent on body size?

    PubMed

    Sikora, Anna B; Petzoldt, Thomas; Dawidowicz, Piotr; von Elert, Eric

    2016-10-01

    Fatty acids contribute to the nutritional quality of the phytoplankton and, thus, play an important role in Daphnia nutrition. One of the polyunsaturated fatty acids (PUFAs)--eicosapentaenoic acid (EPA)--has been shown to predict carbon transfer between primary producers and consumers in lakes, suggesting that EPA limitation of Daphnia in nature is widespread. Although the demand for EPA must be covered by the diet, the demand of EPA in Daphnia that differ in body size has not been addressed yet. Here, we hypothesize that the demand for EPA in Daphnia is size-dependent and that bigger species have a higher EPA demand. To elucidate this, a growth experiment was conducted in which at 20 °C three Daphnia taxa (small-sized D. longispina complex, medium-sized D. pulicaria, and large-bodied D. magna) were fed Synechococcus elongatus supplemented with cholesterol and increasing concentrations of EPA. In addition, fatty acid analyses of Daphnia were performed. Our results show that the saturation threshold for EPA-dependent growth increased with increasing body size. This increase in thresholds with body size may provide another mechanism contributing to the prevalence of small-bodied cladocera in warm habitats and to the midsummer decline of large cladocera in eutrophic water bodies.

  4. Chronic toxicity of biphenyl to Daphnia magna Straus

    SciTech Connect

    Gersich, F.M.; Bartlett, E.A.; Murphy, P.G.; Milazzo, D.P. )

    1989-09-01

    The US Environmental Protection Agency (EPA) issued a final test rule (1985) for biphenyl on the authority of Section 4(a) of the Toxic Substances Control Act (TSCA). Contained within this rule was the requirement for generating chronic daphnid toxicity data for biphenyl. Biphenyl is used primarily to produce dye carriers, heat-transfer fluids and alkylated biphenyls. The acute toxicity of biphenyl to Daphnia magna has been reported. The 48-hr LC50 values were 4.7 and 2.1 mg/L, respectively. To date, the chronic toxicity of biphenyl to fish and aquatic invertebrates has not been investigated. The objective of this study was to determine the chronic toxicity of biphenyl to D. magna. The daphnid chronic toxicity test is designed to estimate the maximum acceptable toxicant concentration (MATC). The MATC is defined as the concentration falling between the highest concentration showing no effect and the next higher concentration showing a toxic effect when compared to the controls.

  5. Acute toxicity of cyanogen chloride to Daphnia magna

    SciTech Connect

    Kononen, D.W.

    1988-09-01

    The destruction of cyanide in waste waters by chlorination has been shown to result in the formation of the extremely toxic compound, cyanogen chloride. Industrial cyanide-containing waste waters may be treated by a batch chlorination process under highly alkaline conditions prior to being discharged into a receiving water systems. Alternatively, if the concentration of cyanide is relatively low, and such waste waters may be diverted to municipal waste treatment facilities where they may be subjected to a process of chlorination which may not be sufficient for the complete oxidative destruction of the available cyanide. Although a large body of literature exists concerning the toxicity of HCN and metallic cyanide compounds to aquatic organisms, there is a comparative scarcity of information concerning cyanogen chloride toxicity. This study was designed to determine the acute toxicity of CNCl to Daphnia magna neonates under static bioassay conditions.

  6. SMALL SCALE MASS CULTURE OF DAPHNIA MAGNA STRAUS

    SciTech Connect

    Rees, John T.; Oldfather, Joan M.

    1980-03-01

    Daphnia magna Straus 1820 was reared on a defined medium in 4-liter flasks under controlled conditions of light, temperature and species of algal food. Adult D. magna were found to be tolerant to high levels of ammonia, up to 108 {micro}M, at high pH (>10), although parthenogenic reproduction may be inhibited at these high levels. Scenedesmus quadricauda and Ankistrodesmus sp. were found to be satisfactory food sources. Densities of greater than one animal per ml in culture were attained utilizing Ankistrodesmus sp. as a food source at a pH of 7.7. Maintenance of pH at around 7-8 appears to be important to successful D. magna culture.

  7. Daphnia swarms: from single agent dynamics to collective vortex formation

    NASA Astrophysics Data System (ADS)

    Ordemann, Anke; Balazsi, Gabor; Caspari, Elizabeth; Moss, Frank

    2003-05-01

    Swarm theories have become fashionable in theoretical physics over the last decade. They span the range of interactions from individual agents moving in a mean field to coherent collective motions of large agent populations, such as vortex-swarming. But controlled laboratory tests of these theories using real biological agents have been problematic due primarily to poorly known agent-agent interactions (in the case of e.g. bacteria and slime molds) or the large swarm size (e.g. for flocks of birds and schools of fish). Moreover, the entire range of behaviors from single agent interactions to collective vortex motions of the swarm have here-to-fore not been observed with a single animal. We present the results of well defined experiments with the zooplankton Daphnia in light fields showing this range of behaviors. We interpret our results with a theory of the motions of self-propelled agents in a field.

  8. Rapid evolution of thermal tolerance in the water flea Daphnia

    NASA Astrophysics Data System (ADS)

    Geerts, A. N.; Vanoverbeke, J.; Vanschoenwinkel, B.; van Doorslaer, W.; Feuchtmayr, H.; Atkinson, D.; Moss, B.; Davidson, T. A.; Sayer, C. D.; De Meester, L.

    2015-07-01

    Global climate is changing rapidly, and the degree to which natural populations respond genetically to these changes is key to predicting ecological responses. So far, no study has documented evolutionary changes in the thermal tolerance of natural populations as a response to recent temperature increase. Here, we demonstrate genetic change in the capacity of the water flea Daphnia to tolerate higher temperatures using both a selection experiment and the reconstruction of evolution over a period of forty years derived from a layered dormant egg bank. We observed a genetic increase in thermal tolerance in response to a two-year ambient +4 °C selection treatment and in the genotypes of natural populations from the 1960s and 2000s hatched from lake sediments. This demonstrates that natural populations have evolved increased tolerance to higher temperatures, probably associated with the increased frequency of heat waves over the past decades, and possess the capacity to evolve increased tolerance to future warming.

  9. Experimental assessment of environmental influences on the stable isotopic composition of Daphnia pulicaria and their ephippia

    NASA Astrophysics Data System (ADS)

    Schilder, J.; Tellenbach, C.; Möst, M.; Spaak, P.; van Hardenbroek, M.; Wooller, M. J.; Heiri, O.

    2015-02-01

    The stable isotopic composition of fossil resting eggs (ephippia) of Daphnia spp. is being used to reconstruct past environmental conditions in lake ecosystems. However, the underlying assumption that the stable isotopic composition of the ephippia reflects the stable isotopic composition of the parent Daphnia, of their diet and of the environmental water have yet to be confirmed in a controlled experimental setting. We performed experiments with Daphnia pulicaria cultures, which included a control treatment conducted at 12 °C in filtered lake water and with a diet of fresh algae, and three treatments in which we manipulated the stable carbon isotopic composition (δ13C value) of the algae, stable oxygen isotopic composition (δ18O value) of the water, and the water temperature, respectively. The stable nitrogen isotopic composition (δ15N value) of the algae was similar for all treatments. At 12 °C, differences in algal δ13C values and in δ18O values of water are reflected in those of Daphnia. The differences between ephippia and Daphnia stable isotope ratios were similar in the different treatments (δ13C: + 0.2 ± 0.4‰ (SD); δ15N: -1.6 ± 0.4‰; δ18O: -0.9 ± 0.4‰) indicating that changes in dietary δ13C and δ18O values of water are passed on to these fossilizing structures. A higher water temperature (20 °C) resulted in lower δ13C values in Daphnia and ephippia than in the other treatments with the same food source and in a minor change in the difference between δ13C values of ephippia and Daphnia (to -1.3 ± 0.3‰). This may have been due to microbial processes or increased algal respiration rates in the experimental containers, which may not affect Daphnia in natural environments. There was no significant difference in the offset between δ18O and δ15N values of ephippia and Daphnia between the 12 °C and 20 °C treatments, but the δ18O values of Daphnia and ephippia were on average 1.2‰ lower at 20 °C compared with 12 °C. We conclude

  10. Uncovering Cryptic Asexuality in Daphnia magna by RAD Sequencing.

    PubMed

    Svendsen, Nils; Reisser, Celine M O; Dukić, Marinela; Thuillier, Virginie; Ségard, Adeline; Liautard-Haag, Cathy; Fasel, Dominique; Hürlimann, Evelin; Lenormand, Thomas; Galimov, Yan; Haag, Christoph R

    2015-11-01

    The breeding systems of many organisms are cryptic and difficult to investigate with observational data, yet they have profound effects on a species' ecology, evolution, and genome organization. Genomic approaches offer a novel, indirect way to investigate breeding systems, specifically by studying the transmission of genetic information from parents to offspring. Here we exemplify this method through an assessment of self-fertilization vs. automictic parthenogenesis in Daphnia magna. Self-fertilization reduces heterozygosity by 50% compared to the parents, but under automixis, whereby two haploid products from a single meiosis fuse, the expected heterozygosity reduction depends on whether the two meiotic products are separated during meiosis I or II (i.e., central vs. terminal fusion). Reviewing the existing literature and incorporating recombination interference, we derive an interchromosomal and an intrachromosomal prediction of how to distinguish various forms of automixis from self-fertilization using offspring heterozygosity data. We then test these predictions using RAD-sequencing data on presumed automictic diapause offspring of so-called nonmale producing strains and compare them with "self-fertilized" offspring produced by within-clone mating. The results unequivocally show that these offspring were produced by automixis, mostly, but not exclusively, through terminal fusion. However, the results also show that this conclusion was only possible owing to genome-wide heterozygosity data, with phenotypic data as well as data from microsatellite markers yielding inconclusive or even misleading results. Our study thus demonstrates how to use the power of genomic approaches for elucidating breeding systems, and it provides the first demonstration of automictic parthenogenesis in Daphnia.

  11. Uptake, depuration, and bioconcentration of two pharmaceuticals, roxithromycin and propranolol, in Daphnia magna.

    PubMed

    Ding, Jiannan; Lu, Guanghua; Liu, Jianchao; Yang, Haohan; Li, Yi

    2016-04-01

    The objective of the present study was to investigate the uptake, depuration, and bioconcentration of two pharmaceuticals, roxithromycin (ROX) and propranolol (PRP), in Daphnia magna via aqueous exposure. Additionally, dietary and pH effects on the bioconcentration of two pharmaceuticals in daphnia were studied. During the 24-h uptake phase followed by the 24-h depuration phase, the uptake rate constants (k(u)) of ROX for daphnia were 9.21 and 2.77 L kg(-1) h(-1), corresponding to the exposure concentrations of 5 and 100 μg L(-1), respectively; For PRP at the nominal concentrations of 5 and 100 μg L(-1), k(u) were 2.29 and 0.99 L kg(-1) h(-1), respectively. The depuration rate constants (k(d)) of ROX in daphnia, at the exposure concentrations of 5 and 100 μg L(-1), were 0.0985 and 0.207 h(-1), respectively; while those of PRP were 0.0276 and 0.0539 h(-1) for the nominal concentrations of 5 and 100 μg L(-1), respectively. With the decreasing exposure concentrations, the bioconcentration factors (BCFs) in daphnia ranged from 13.4 to 93.5 L kg(-1) for ROX, and 18.4 to 83.0 L kg(-1) for PRP, revealing the considerable accumulation potential of these two pharmaceuticals. Moreover, after 6h exposure, the body burdens of ROX and PRP in dead daphnia were 4.98-6.14 and 7.42-12.9 times higher than those in living daphnia, respectively, implying that body surface sorption dominates the bioconcentration of the two pharmaceuticals in daphnia. In addition, the presence of algal food in the media could significantly elevate the kd values for both ROX and PRP, thereby restraining their bioconcentration in daphnia. A pH-dependent bioconcentration study revealed that the bioconcentration of the two pharmaceuticals in daphnia increased with increasing pH levels, which ranged from 7 to 9. Finally, a model was developed to estimate the relationships between pH and the BCFs of the two pharmaceuticals in zooplankton. The predicted values based on this model were highly consistent

  12. Chronic toxicity of diphenhydramine hydrochloride and erythromycin thiocyanate to Daphnia, Daphnia magna, in a continuous exposure test system

    USGS Publications Warehouse

    Meinertz, J.R.; Schreier, T.M.; Bernardy, J.A.; Franz, J.L.

    2010-01-01

    Diphenhydramine hydrochloride (DH; Benadryl TM, an over-the-counter antihistamine) and erythromycin thiocyanate (ET; a commonly used macrolide antibiotic) are pharmaceutical compounds whose chronic toxicity to Daphnia magna had not been characterized. Continuous exposure to DH concentrations about 5 times greater than the maximum reported environmental concentration of 0.023 lg/L for 21 days or to ET concentrations about 40 times the maximum reported environmental concentration of 6 (mu or u)g/L for 21 days did not significantly impact D. magna survival and production. In this study the no observable effect concentration for DH was 0.12 (mu or u)g/L and for ET was 248 (mu or u)g/L.

  13. Chronic toxicity of diphenhydramine hydrochloride and erythromycin thiocyanate to daphnia, Daphnia magna, in a continuous exposure test system.

    PubMed

    Meinertz, Jeffery R; Schreier, Theresa M; Bernardy, Jeffry A; Franz, Jeanne L

    2010-11-01

    Diphenhydramine hydrochloride (DH; Benadryl™, an over-the-counter antihistamine) and erythromycin thiocyanate (ET; a commonly used macrolide antibiotic) are pharmaceutical compounds whose chronic toxicity to Daphnia magna had not been characterized. Continuous exposure to DH concentrations about 5 times greater than the maximum reported environmental concentration of 0.023 μg/L for 21 days or to ET concentrations about 40 times the maximum reported environmental concentration of 6 μg/L for 21 days did not significantly impact D. magna survival and production. In this study the no observable effect concentration for DH was 0.12 μg/L and for ET was 248 μg/L.

  14. NUTRIENT COMPOSITION DEGRADATION OF DAPHNIA PULICARIA BY A HIGHLY PREVALENT CHYTRIDIOMYCETE FUNGAL PATHOGEN (POLYCARYUM LEAVE) DURING NATURALLY OCCURRING LAKE-WIDE EPIDEMICS.

    EPA Science Inventory

    Despite evidence illustrating that chytridiomycete fungal infection can be highly prevalent in Daphnia (>80%) and that infected individuals are preferentially consumed by fish, no studies have measured the nutritional consequences of using chytrid-infected Daphnia as a food sourc...

  15. The sensitivity of Daphnia magna and Daphnia curvirostris to 10 veterinary antibacterials and to some of their binary mixtures.

    PubMed

    Dalla Bona, Mirco; Di Leva, Vincenzo; De Liguoro, Marco

    2014-11-01

    Aim of this study was to evaluate the suitability of Daphnia curvirostris for the acute toxicity test usually performed on Daphnia magna, and to compare the sensitivity of the two species toward 10 antibacterials [enrofloxacin (EFX), ciprofloxacin(CPX), sulfaguanidine (SGD), sulfadiazine (SDZ), sulfamethazine (SMZ), sulfaquinoxaline (SQO), sulfaclozine (SCZ), sulfamerazine (SMA), sulfadimethoxine (SDM) and trimethoprim (TMP)] and some of their binary mixtures. Furthermore, a tentative prolonged-toxicity test (lasting 13d) was settled up in order to evidence toxic responses with drug concentrations that were uneffective in the classic 48h immobilization test. Results showed that D. curvirostris was more sensitive than D. magna to the majority of compounds (6 out of 10). Lowest 48h EC50s were obtained with EFX (4.3mgL(-1) in D. curvirostris) and SGD (6.2mgL(-1) in D. magna). The toxicity of paired compounds was always concentration-additive or less than concentration-additive. In the prolonged-toxicity test mortality and/or reproduction inhibition were constantly observed. It was concluded that: (1) D. curvirostris could be a suitable model for the evaluation of acute toxicity of antibacterials since its sensitivity was generally greater than that of D. magna; (2) the toxicity of EFX and SGD should be given special attention as the two compounds, in the prolonged test, showed to be active at concentrations of 0.9mgL(-1) and 2.5mgL(-1), respectively; (3) the concentration addition is usually a reasonable worst case estimation of the environmental impact of antibacterial mixtures.

  16. What causes the difference in synergistic potentials of propiconazole and prochloraz toward pyrethroids in Daphnia magna?

    PubMed

    Dalhoff, Kristoffer; Gottardi, Michele; Kretschmann, Andreas; Cedergreen, Nina

    2016-03-01

    Azole fungicides (imidazoles and triazoles) are known to function synergistically with several compounds, especially with pyrethroid insecticides, most likely by inhibiting cytochrome P450. Different azole fungicides have been shown to differ in their synergistic potentials usually with the imidazoles being stronger synergists than the triazoles. This study investigated whether the toxicokinetic and toxicodynamic (TKTD) properties of the imidazole prochloraz and triazole propiconazole can explain their different synergistic potential toward the freshwater macroinvertebrate Daphnia magna. Pulse exposure to external concentrations of propiconazole (1.4μM) and prochloraz (1.7μM) for 18h resulted in internal concentrations of 22.7 and 53.5μmolkg(-1)w.w. for propiconazole and prochloraz, respectively. This 2-fold difference in bioaccumulation corresponded very well with the observed 2.7-fold lower external EC50-estimate (7 days) for prochloraz compared to propiconazole. The estimated IC50 for the in vivo inhibition of cytochrome P450 (ECOD) activity, however, measured as transformation of 7-ethoxycoumarin into 7-hydroxycoumarin, was almost 500-fold higher for prochloraz (IC50: 0.011±0.002μM) compared to propiconazole (IC50: 4.9±0.06μM). When indirectly measuring the binding strength of the two azoles, daphnids exposed to propiconazole recovered roughly 80% of their ECOD activity compared to the control shortly after being moved to azole-free medium, indicating that propiconazole causes reversible inhibition of cytochrome P450. In contrast, the ECOD-activity remained inhibited in the prochloraz-exposed daphnids for 12h following transfer to azole-free medium, which correlated with elimination of the measured internal prochloraz concentration (DT95≈13h). These results indicate that lethal toxicity of the azole fungicides is mainly driven by toxicokinetics through their hydrophobicities resulting in different internal concentrations. Their synergistic potential

  17. Salting our freshwater lakes.

    PubMed

    Dugan, Hilary A; Bartlett, Sarah L; Burke, Samantha M; Doubek, Jonathan P; Krivak-Tetley, Flora E; Skaff, Nicholas K; Summers, Jamie C; Farrell, Kaitlin J; McCullough, Ian M; Morales-Williams, Ana M; Roberts, Derek C; Ouyang, Zutao; Scordo, Facundo; Hanson, Paul C; Weathers, Kathleen C

    2017-04-10

    The highest densities of lakes on Earth are in north temperate ecosystems, where increasing urbanization and associated chloride runoff can salinize freshwaters and threaten lake water quality and the many ecosystem services lakes provide. However, the extent to which lake salinity may be changing at broad spatial scales remains unknown, leading us to first identify spatial patterns and then investigate the drivers of these patterns. Significant decadal trends in lake salinization were identified using a dataset of long-term chloride concentrations from 371 North American lakes. Landscape and climate metrics calculated for each site demonstrated that impervious land cover was a strong predictor of chloride trends in Northeast and Midwest North American lakes. As little as 1% impervious land cover surrounding a lake increased the likelihood of long-term salinization. Considering that 27% of large lakes in the United States have >1% impervious land cover around their perimeters, the potential for steady and long-term salinization of these aquatic systems is high. This study predicts that many lakes will exceed the aquatic life threshold criterion for chronic chloride exposure (230 mg L(-1)), stipulated by the US Environmental Protection Agency (EPA), in the next 50 y if current trends continue.

  18. Secondary production of freshwater zooplankton communities exposed to a fungicide and to a petroleum distillate in outdoor pond mesocosms.

    PubMed

    Bayona, Yannick; Roucaute, Ana; Roucaute, Marc; Gorzerino, Caroline; Cailleaud, Kevin; Lagadic, Laurent; Bassères, Anne; Caquet, Thierry

    2014-04-01

    Ecological risk assessment of chemicals in mesocosms requires measurement of a large number of parameters at the community level. Studies on invertebrate communities usually focus on taxonomic approaches, which only provide insights into taxonomic structure changes induced by chemicals. In the present study, abundance, biomass (B), theoretical production (P), and instantaneous P/B ratio were used as endpoints to assess the effects of the commercial form of the dithiocarbamate fungicide thiram (35 µg/L and 170 µg/L nominal concentrations) and of the hydrocarbon water accommodated fraction (HWAF) of a petroleum distillate (0.01 mg/L, 0.4 mg/L, 2 mg/L, and 20 mg/L loadings) on the zooplankton community in freshwater pond mesocosms. Endpoints were measured during a 4-wk treatment period (1 pulse/wk) followed by a 5-mo posttreatment period to evaluate zooplankton population recovery. The chlorophyll a concentration in water was significantly increased after treatment with HWAF, whereas it was not affected by thiram treatment. Zooplankton abundance-based analysis showed effects on a limited number of taxa, whereas other endpoints (mainly the P/B ratio) revealed that more taxa were impacted, with recovery depending on the chemical and concentration. Exposure to HWAF mainly had a negative impact on cladocerans, which resulted in top-down effects (between cladocerans and phytoplankton). Thiram negatively affected rotifers and copepods, suggesting more direct toxic effects. The results show that the use of secondary production as an endpoint provides a more comprehensive assessment of potential direct and indirect effects of chemicals on a community, and they also support evidence of alteration in functional processes.

  19. Turning inducible defenses on and off: adaptive responses of Daphnia to a gape-limited predator.

    PubMed

    Riessen, Howard P; Trevett-Smith, Julie B

    2009-12-01

    The use of inducible defenses is a common strategy to reduce predation while minimizing associated costs for prey. The most effective use of these defenses, however, may involve turning them on and off at different stages of ontogenetic development, with the timing dependent on prey body size and the nature of the predation environment. We develop a model based on the strike efficiency of a size-selective predator that examines the interaction between induced morphological defenses and prey body size, including the consequences of this interaction for the optimal development of the defenses during the prey's ontogeny. We then examine this model with respect to a model system of inducible defenses: neck spine induction in the water flea Daphnia in response to predatory larvae of the phantom midge Chaoborus. In accordance with predictions of the model, the body size and timing of neck spine acquisition during Daphnia development are related to the relative sizes of the Daphnia and Chaoborus species interacting in a pond or lake. The Daphnia species examined first acquire neck spines in either the first, second, or third juvenile instar, at body lengths that range from 0.58 to 0.83 mm. Neck spine formation is initiated at larger Daphnia body sizes when these prey are subject to predation by a larger Chaoborus species (C. trivittatus) and at smaller sizes when exposed only to a smaller predator (C. americanus). Induction of these morphological defenses in Daphnia occurs later in juvenile development in the smaller of the two species we examined (D. minnehaha) than in the larger (D. pulex). Delayed acquisition of neck spines also occurs when Daphnia are exposed to predation by larger Chaoborus. The close match between model predictions and the patterns observed in nature suggests that these patterns are adaptive developmental responses to different predator environments.

  20. Chlorine toxicity to early life stages of freshwater mussels (Bivalvia: Unionidae).

    PubMed

    Valenti, Theodore W; Cherry, Donald S; Currie, Rebecca J; Neves, Richard J; Jones, Jess W; Mair, Rachel; Kane, Cynthia M

    2006-09-01

    Chlorine (Cl) is a highly toxic, widely used halogen disinfectant that is present in point-source pollution discharges from wastewater treatment plants and industrial facilities. The U.S. Environmental Protection Agency freshwater criteria for Cl are 19 microg total residual Cl (TRC)/L as a maximum 1-h average concentration and 11 microg TRC/L as a maximum 4-d average; however, toxicological data for unionids were not used in these calculations. To address this void in the data, we conducted acute tests with glochidia from several species and 21-d bioassays with three-month-old Epioblasma capsaeformis and three-, six-, and 12-month-old Villosa iris juveniles. The 24-h lethal concentration 50 values for glochidia were between 70 and 220 [Lg TRC/L, which are 2.5 to 37 times higher than those reported in other studies for cladocerans. Significant declines in growth and survivorship were observed in the 21-d test with E. capsaeformis at 20 microg TRC/L. Lowest-observed-adverse-effects concentrations in bioassays with juvenile V. iris were higher (30-60 microg TRC/L) but showed a significant trend of declining toxicity with increased age. Although endpoints were above water quality criteria, the long life spans of unionids and potential implications of chronic exposure to endangered juvenile mussels still warrant concern.

  1. Chlorine toxicity to early life stages of freshwater mussels (Bivalvia: Unionidae)

    USGS Publications Warehouse

    Valenti, T.W.; Cherry, D.S.; Currie, R.J.; Neves, R.J.; Jones, J.W.; Mair, R.; Kane, C.M.

    2006-01-01

    Chlorine (Cl) is a highly toxic, widely used halogen disinfectant that is present in point-source pollution discharges from wastewater treatment plants and industrial facilities. The U.S. Environmental Protection Agency freshwater criteria for Cl are 19 ??g total residual Cl (TRC)/L as a maximum 1-h average concentration and 11 ??g TRC/L as a maximum 4-d average; however, toxicological data for unionids were not used in these calculations. To address this void in the data, we conducted acute tests with glochidia from several species and 21-d bioassays with three-month-old Epioblasma capsaeformis and three-, six-, and 12-month-old Villosa iris juveniles. The 24-h lethal concentration 50 values for glochidia were between 70 and 220 ??g TRC/L, which are 2.5 to 37 times higher than those reported in other studies for cladocerans. Significant declines in growth and survivorship were observed in the 21-d test with E. capsaeformis at 20 ??g TRC/L. Lowest-observed-adverse- effects concentrations in bioassays with juvenile V. iris were higher (30-60 ??g TRC/L) but showed a significant trend of declining toxicity with increased age. Although endpoints were above water quality criteria, the long life spans of unionids and potential implications of chronic exposure to endangered juvenile mussels still warrant concern. ?? 2006 SETAC.

  2. Phenotypic plasticity in freshwater picocyanobacteria.

    PubMed

    Huber, Paula; Diovisalvi, Nadia; Ferraro, Marcela; Metz, Sebastián; Lagomarsino, Leonardo; Llames, María Eugenia; Royo-Llonch, Marta; Bustingorry, José; Escaray, Roberto; Acinas, Silvia G; Gasol, Josep M; Unrein, Fernando

    2017-03-01

    Picocyanobacteria can occur as single-cell (Pcy) or as colonies (CPcy). Published evidence suggests that some Pcy strains have the capability to aggregate under certain culture conditions, however this has not been demonstrated to occur in natural environments. We investigated whether the Pcy and CPcy belong to the same species (i.e. phylotype), and the factors that determine their morphological and genetic variability in a hypertrophic shallow lake dominated by picocyanobacteria. Six main different morphologies and >30 phylotypes were observed. All sequences retrieved belonged to the 'Anathece + Cyanobium' clade (Synechococcales) that are known to have the capability of aggregation/disaggregation. The temporal variation of picocyanobacteria morphotype composition was weakly correlated with the DGGE temporal pattern, and could be explained by the composition of the zooplankton assemblage. Laboratory experiments confirmed that the small cladoceran Bosmina favoured the dominance of CPcy, i.e. Cyanodictyon doubled the size of the colonies when present, most likely through the aggregation of single-cell picocyanobacteria into colonies. Flow cytometry cell sorting and 16S rRNA + ITS sequencing of the Pcy and CPcy cytometrically-defined populations revealed that some phylotypes could be found in both sorted populations, suggesting phenotypic plasticity in which various Synechococcales phylotypes could be found in situ either as single-cells or as colonies.

  3. The components of the Daphnia pulex immune system as revealed by complete genome sequencing

    PubMed Central

    McTaggart, Seanna J; Conlon, Claire; Colbourne, John K; Blaxter, Mark L; Little, Tom J

    2009-01-01

    Background Branchiopod crustaceans in the genus Daphnia are key model organisms for investigating interactions between genes and the environment. One major theme of research on Daphnia species has been the evolution of resistance to pathogens and parasites, but lack of knowledge of the Daphnia immune system has limited the study of immune responses. Here we provide a survey of the immune-related genome of D. pulex, derived from the newly completed genome sequence. Genes likely to be involved in innate immune responses were identified by comparison to homologues from other arthropods. For each candidate, the gene model was refined, and we conducted an analysis of sequence divergence from homologues from other taxa. Results and conclusion We found that some immune pathways, in particular the TOLL pathway, are fairly well conserved between insects and Daphnia, while other elements, in particular antimicrobial peptides, could not be recovered from the genome sequence. We also found considerable variation in gene family copy number when comparing Daphnia to insects and present phylogenetic analyses to shed light on the evolution of a range of conserved immune gene families. PMID:19386092

  4. Summer water clarity responses to phosphorus, Daphnia grazing, and internal mixing in Lake Mendota

    USGS Publications Warehouse

    Lathrop, R.C.; Carpenter, S.R.; Robertson, D.M.

    1999-01-01

    Linear models were developed for predicting mean Secchi disk depth readings as a measure of water clarity for the summer months in Lake Mendota, Wisconsin. The 20-yr (1976-1995) data set also included external phosphorus (P) loadings and in-lake April P concentrations as indices of lake nutrient status, and monthly (28 d) water column stabilities and Daphnia biomasses as indices of lake mixing and algal grazing potentials, respectively. June Secchi depths were mostly controlled by food web dynamics, which dictated whether the larger-bodied Daphnia pulicaria or the smaller-bodied D. galeata mendotae dominated during the spring clear-water phase. May Daphnia biomasses were significantly greater in D. pulicaria-dominated years than in D. galeata-dominated years; D. pulicaria-year biomasses were also greater during the summer months. The model for the midsummer (July-August) months indicated that Secchi depths were inversely related to April P concentrations and positively related to midsummer Daphnia biomasses and lake stabilities. Scenarios for midsummer Secchi depths were tested using the observed minimum and maximum values for each predictor variate. While holding two variates constant, April P, Daphnia biomass, and lake stability each resulted in relatively similar Secchi ranges (0.81, 0.81, and 1.17 m, respectively). Our results suggest that summer water clarity in eutrophic Lake Mendota is controlled by interacting ecosystem processes linked to land use activities, lake food web dynamics, and climate.

  5. Tertiary treatment for wastewater reuse based on the Daphnia magna filtration - comparison with conventional tertiary treatments.

    PubMed

    Serra, Teresa; Colomer, Jordi; Pau, Conxi; Marín, Maribel; Sala, Lluís

    2014-01-01

    Tertiary treatments are required to permit safe reuse of wastewater. The performance of a new biological tertiary treatment based on the filtration by a population of Daphnia magna was studied and compared with the performance of other conventional tertiary treatments such as coagulation-flocculation, settling tank, disc filtration, sand filtering and ultraviolet (UV) light. The analysis was based on the efficiency in the particle removal and Escherichia coli inactivation. The Daphnia magna treatment reduced the concentration of particles with diameters below 30 μm by 35%, depending on abiotic parameters such as water temperature and the hydraulic retention time (HRT). The Daphnia magna filtration increased with water temperature for water temperatures >20 °C, while it remained constant for water temperatures <20 °C. Lower HRTs induced the growth of the Daphnia magna population, maintaining the same water quality. Furthermore, the Daphnia magna treatment inactivated E. coli in 1.2 log units. This inactivation was six times larger than that obtained by the conventional macrofiltration systems analyzed, although lower than the inactivation attained by UV light, which ranged between 1.5 and 4 log units.

  6. The distribution of the heavy metal accumulation rate in the biomass of three Daphnia species

    SciTech Connect

    Gajula, V.K.; Hovorka, J.; Stuchlik, E.

    1995-12-31

    The difference in the accumulation rate of a mixture of heavy metals in aquatic organisms is of considerable interest because of its importance in the prediction of the effect of pollutants in aquatic systems. In this study the authors are making an effort to evaluate the accumulation patterns of pollutants in aquatic organisms by establishing a relation between the level of an accumulated mixture of heavy metals (Cd, Zn, Pb, As, Hg) in individuals of Daphnia magna, Daphnia pulicaria and Daphnia galeata and its dry weight with respect to the form of heavy metals in the aquatic environment. One age group of Daphnia species (10 day old) were exposed to 5 ppb, 10 ppb and 20 ppb of the mixture of heavy metals for 24 hours in three different experiments. In the first experiment the mixture of heavy metals was present exclusively in labelled algae (Scendesmus actus), in the second in an aquatic medium with non labelled algae, and in the third experiment the mixture of heavy metals was dissolved in the aquatic medium only without the addition of algae. The concentration of the heavy metal mixture in individuals of D.magna; D.pulicaria and D.galeata was determined using atomic absorption spectrometry. Results were statistically evaluated and the rate of accumulation and influence of various heavy metals in the biomass of three Daphnia species is discussed.

  7. The " Daphnia" Lynx Mark I Suborbital Flight Experiment: Hardware Qualification at the Drop Tower Bremen

    NASA Astrophysics Data System (ADS)

    Knie, Miriam; Schoppmann, Kathrin; Eck, Hendrik; Ribeiro, Bernard Wolfschoon; Laforsch, Christian

    2016-06-01

    The Drop Tower Bremen, a ground-based facility enabling research under real microgravity conditions, is an excellent platform for testing new types of experimental hardware to ensure full performance when deployed in costly and rare flight opportunities such as suborbital flights. Here we describe the " Daphnia" experiment which will fly on XCOR Aerospace Lynx Mark I and our experience from the hardware tests with the catapult system at the drop tower. The aim of the " Daphnia" experiment is to obtain data on the biological performance of daphnids and predator-prey interactions in microgravity, which are important for the development of aquatic bioregenerative life support systems (BLSS). The experiment consists of two subunits: The first unit is dedicated to predator-prey interactions, where behavioural analysis should reveal if microgravity interfere with prey ( Daphnia) detection or feeding and therefore may interrupt the trophic cascade. The functioning of such an artificial food web is indispensable for a long-lasting BLSS suitable for long-duration manned space missions or Earth-based explorations to extreme habitats. The second unit is designed to investigate the impact of microgravity on gene expression and the cytoskeleton in Daphnia. Next to data collection, the real microgravity conditions at the drop tower have helped to identify the weak points of the " Daphnia" experimental hardware and lead to further improvement. Hence, the drop tower is ideal for testing new experimental hardware which is indispensable before the implementation in suborbital flights.

  8. Daphnia's dilemma: adjustment of carbon budgets in the face of food and cholesterol limitation.

    PubMed

    Lukas, Marcus; Wacker, Alexander

    2014-04-01

    We studied the carbon (C) metabolism in Daphnia when the amount of C (food quantity) and/or the content of biochemical nutrients (food quality) was limiting. Growth performances and C budgets of Daphnia magna (assimilation, faeces egestion, excretion and respiration measured by [(14)C]-tracing) were analysed when animals were raised on different food quantities and concentrations of cholesterol, an essential biochemical food compound. Cholesterol is of special interest because it not only acts as limiting nutrient but also contributes to the overall C pool of the animals. As the tissue cholesterol concentration in Daphnia is quite low, we hypothesized the selective exclusion of cholesterol from C budgeting and tested this using radiolabelled cholesterol. Somatic growth rates of D. magna were highest at high quantity and quality and were reduced to a moderate value if either the food quantity or the cholesterol concentration was low. Growth was lowest at low food quantity and quality. The measurements of C budgets revealed high regulative response to low food quality at high food quantity only. Here, low dietary cholesterol caused bulk C assimilation efficiency (AE) to decrease and assimilated (excess) C to be increasingly respired. Additionally, Daphnia enhanced efficient adjustment of C budgets when facing cholesterol limitation by (1) increasing the AE of the cholesterol itself and (2) not changing cholesterol respiration, which was still not detectable. In contrast, at low food quantity, Daphnia is unable to adjust for low food quality, emphasizing that food limitation could overrule food quality effects.

  9. Do Daphnia use metalimnetic organic matter in a north temperate lake? An analysis of vertical migration

    USGS Publications Warehouse

    Brosseau, Chase Julian; Cline, Timothy J.; Cole, Jonathan J.; Hodgson, James R.; Pace, Michael L.; Weidel, Brian C.

    2012-01-01

    Diel vertical migration of zooplankton is influenced by a variety of factors including predation, food, and temperature. Research has recently shifted from a focus on factors influencing migration to how migration affects nutrient cycling and habitat coupling. Here we evaluate the potential for Daphnia migrations to incorporate metalimnetic productivity in a well-studied northern Wisconsin lake. We use prior studies conducted between 1985 and 1990 and current diel migration data (2008) to compare day and night Daphnia vertical distributions with the depth of the metalimnion (between the thermocline and 1% light depth). Daphnia migrate from a daytime mean residence depth of between about 1.7 and 2.5 m to a nighttime mean residence depth of between 0 and 2.0 m. These migrations are consistent between the prior period and current measurements. Daytime residence depths of Daphnia are rarely deep enough to reach the metalimnion; hence, metalimnetic primary production is unlikely to be an important resource for Daphnia in this system.

  10. Complementary population dynamics of exotic and native Daphnia in North American reservoir communities

    USGS Publications Warehouse

    Havel, J.E.; Graham, J.L.

    2006-01-01

    During its invasion of North America, the exotic Daphnia lumholtzi has rapidly colonized numerous reservoirs, natural lakes, and large rivers. In the current study, we examine the overlap between D. lumholtzi and native Daphnia species through analysis of two data sets: co-occurrence in reservoirs of the south-central United States and population dynamics in one reservoir. In 171 reservoirs and oxbow lakes, D. lumholtzi was among the most prevalent species and its distribution was independent of other Daphnia species. Over a 28-month period in Stockton Lake, Missouri, D. lumholtzi was abundant only in late summer, a period when the epilimnion was warm (25-30??C) and cyanobacteria were common. Native Daphnia (D. mendotae, D. parvula, and D. retrocurva) complemented this pattern, being generally rare in summer and most abundant during winter and spring. Peak densities and average fecundities of native Daphnia during the cooler months were typically greater than densities and fecundities of D. lumholtzi in summer. The complementary population dynamics between native and exotic species may be significant for the food webs in warm reservoirs, with D. lumholtzi providing another food resource when the abundance of large zooplankton is ordinarily low. ?? 2006 E. Schweizerbart'sche Verlagsbuchhandlung.

  11. Acute and chronic toxicity of emerging contaminants, alone or in combination, in Chlorella vulgaris and Daphnia magna.

    PubMed

    Pablos, María Victoria; García-Hortigüela, Pilar; Fernández, Carlos

    2015-04-01

    This work presents the toxicity results of different compounds classified as emerging contaminants on primary producers and primary consumers in the aquatic compartment. The objectives were to (1) obtain acute and chronic toxicity results for algae and Daphnia magna using standardised or currently used tests, (2) study the relationship between the effects on the impaired feeding rate for daphnia and the effects of reproduction and (3) examine the responses on daphnia and algae after binary combinations of environmentally relevant compounds and perfluorooctane sulfonate (PFOS). Toxicity data on personal care products (PCPs), not reported in the scientific literature up to now, are presented. The results confirmed that the Daphnia feeding bioassay can be a sensitive, ecologically relevant endpoint to detect sublethal effects and could complement the information obtained with the reproduction test on Daphnia. The results also suggested that the concomitant occurrence of PFOS and other emerging contaminants in the aquatic compartment could affect the toxicity of some compounds according to their lipophilicity.

  12. COMMUNICATION: Stochastic resonance and the evolution of Daphnia foraging strategy

    NASA Astrophysics Data System (ADS)

    Dees, Nathan D.; Bahar, Sonya; Moss, Frank

    2008-12-01

    Search strategies are currently of great interest, with reports on foraging ranging from albatrosses and spider monkeys to microzooplankton. Here, we investigate the role of noise in optimizing search strategies. We focus on the zooplankton Daphnia, which move in successive sequences consisting of a hop, a pause and a turn through an angle. Recent experiments have shown that their turning angle distributions (TADs) and underlying noise intensities are similar across species and age groups, suggesting an evolutionary origin of this internal noise. We explore this hypothesis further with a digital simulation (EVO) based solely on the three central Darwinian themes: inheritability, variability and survivability. Separate simulations utilizing stochastic resonance (SR) indicate that foraging success, and hence fitness, is maximized at an optimum TAD noise intensity, which is represented by the distribution's characteristic width, σ. In both the EVO and SR simulations, foraging success is the criterion, and the results are the predicted characteristic widths of the TADs that maximize success. Our results are twofold: (1) the evolving characteristic widths achieve stasis after many generations; (2) as a hop length parameter is changed, variations in the evolved widths generated by EVO parallel those predicted by SR. These findings provide support for the hypotheses that (1) σ is an evolved quantity and that (2) SR plays a role in evolution.

  13. Bacteria-mediated effects of antibiotics on Daphnia nutrition.

    PubMed

    Gorokhova, Elena; Rivetti, Claudia; Furuhagen, Sara; Edlund, Anna; Ek, Karin; Breitholtz, Magnus

    2015-05-05

    In polluted environments, contaminant effects may be manifested via both direct toxicity to the host and changes in its microbiota, affecting bacteria-host interactions. In this context, particularly relevant is exposure to antibiotics released into environment. We examined effects of the antibiotic trimethoprim on microbiota of Daphnia magna and concomitant changes in the host feeding. In daphnids exposed to 0.25 mg L(-1) trimethoprim for 24 h, the microbiota was strongly affected, with (1) up to 21-fold decrease in 16S rRNA gene abundance and (2) a shift from balanced communities dominated by Curvibacter, Aquabacterium, and Limnohabitans in controls to significantly lower diversity under dominance of Pelomonas in the exposed animals. Moreover, decreased feeding and digestion was observed in the animals exposed to 0.25-2 mg L(-1) trimethoprim for 48 h and then fed 14C-labeled algae. Whereas the proportion of intact algal cells in the guts increased with increased trimethoprim concentration, ingestion and incorporation rates as well as digestion and incorporation efficiencies decreased significantly. Thus, antibiotics may impact nontarget species via changes in their microbiota leading to compromised nutrition and, ultimately, growth. These bacteria-mediated effects in nontarget organisms may not be unique for antibiotics, but also relevant for environmental pollutants of various nature.

  14. Toxicity of new generation flame retardants to Daphnia magna.

    PubMed

    Waaijers, Susanne L; Hartmann, Julia; Soeter, A Marieke; Helmus, Rick; Kools, Stefan A E; de Voogt, Pim; Admiraal, Wim; Parsons, John R; Kraak, Michiel H S

    2013-10-01

    There is a tendency to substitute frequently used, but relatively hazardous brominated flame retardants (BFRs) with halogen-free flame retardants (HFFRs). Consequently, information on the persistence, bioaccumulation and toxicity (PBT) of these HFFRs is urgently needed, but large data gaps and inconsistencies exist. Therefore, in the present study the toxicity of a wide range of HFFRs to the water flea Daphnia magna was investigated. Our results revealed that four HFFRs were showing no effect at their Sw (saturated water concentration) and three had a low toxicity (EC50>10 mg L(-1)), suggesting that these compounds are not hazardous. Antimony trioxide had a moderate toxicity (EC50=3.01 mg L(-1), 95% CL: 2.76-3.25) and triphenyl phosphate and the brominated reference compound tetra bromobisphenol A were highly toxic to D. magna (EC50=0.55 mg L(-1), 95% CL: 0.53-0.55 and EC50=0.60 mg L(-1), 95% CL: 0.24-0.97 respectively). Aluminum trihydroxide and bisphenol A bis(diphenyl phosphate) caused limited mortality at Sw (26 and 25% respectively) and have a low solubility (<10 mg L(-1)). Hence, increased toxicity of these compounds may be observed when for instance decreasing pH could increase solubility. By testing all compounds under identical conditions we provided missing insights in the environmental hazards of new generation flame retardants and propose as best candidates for BFR replacements: APP, ALPI, DOPO, MHO, MPP, ZHS and ZS.

  15. Adaptation to local ultraviolet radiation conditions among neighbouring Daphnia populations.

    PubMed

    Miner, Brooks E; Kerr, Benjamin

    2011-05-07

    Understanding the historical processes that generated current patterns of phenotypic diversity in nature is particularly challenging in subdivided populations. Populations often exhibit heritable genetic differences that correlate with environmental variables, but the non-independence among neighbouring populations complicates statistical inference of adaptation. To understand the relative influence of adaptive and non-adaptive processes in generating phenotypes requires joint evaluation of genetic and phenotypic divergence in an integrated and statistically appropriate analysis. We investigated phenotypic divergence, population-genetic structure and potential fitness trade-offs in populations of Daphnia melanica inhabiting neighbouring subalpine ponds of widely differing transparency to ultraviolet radiation (UVR). Using a combination of experimental, population-genetic and statistical techniques, we separated the effects of shared population ancestry and environmental variables in predicting phenotypic divergence among populations. We found that native water transparency significantly predicted divergence in phenotypes among populations even after accounting for significant population structure. This result demonstrates that environmental factors such as UVR can at least partially account for phenotypic divergence. However, a lack of evidence for a hypothesized trade-off between UVR tolerance and growth rates in the absence of UVR prevents us from ruling out the possibility that non-adaptive processes are partially responsible for phenotypic differentiation in this system.

  16. Evolutionary ecotoxicology of pesticide resistance: a case study in Daphnia.

    PubMed

    Jansen, Mieke; Coors, Anja; Stoks, Robby; De Meester, Luc

    2011-05-01

    Natural populations that are exposed to pesticides in their environment may at the same time be exposed to natural stressors like parasites and predators, which may interact with pesticide exposure. This may not only impact target pest species but also a wide variety of non-target species. This review reports on a joint research program in the water flea Daphnia magna, a non-target species often used as model organism in ecology and ecotoxicology. The focus is on different aspects that are of key importance to understand the evolutionary ecology of pesticide exposure: (1) the capacity of natural populations to genetically adapt to pesticide exposure (2) the added complexity of synergistic effects caused by simultaneous exposure to natural stressors, and (3) the potential interference of evolutionary costs of adaptation to pesticide exposure. Our results showed that natural populations were able to rapidly evolve resistance to the pesticide carbaryl but at the expense of fitness costs. Individuals selected for carbaryl resistance had higher survival rates when exposed to the pesticide but also a greater susceptibility to the challenge imposed by the bacterial endoparasite Pasteuria ramosa. The evolved resistance to carbaryl was in some cases only expressed in the absence of fish kairomones. Further, it became clear that the responses to both exposure to single and combined stressors was for several life history variables strongly dependent upon past exposure to carbaryl. This indicates that past exposures to pesticides are important and can not be neglected when evaluating responses to current stressors.

  17. Sublethal effects of phenanthrene, nicotine, and pinane on Daphnia pulex

    USGS Publications Warehouse

    Savino, Jacqueline F.; Tanabe, Lila L.

    1989-01-01

    Chronic studies of Daphnia Pulex exposed to different concentrations of phenanthrene, nicotine, and pinane produced consistent sublethal effects among replicates and concentrations. The LOEC's for growth and fecundity with each chemical tested were 3 to 30% of the 48-hr EC50's. Growth decreased as concentration increased for each chemical tested, and fecundity approached zero at 2 to 5 times the LOEC for each chemical. In this study chemicals representing PAHs, heterocyclic nitrogen compounds, and cyclic alkanes, produced detectable sublethal effects in daphnids at less than 0.1 ppm in water. These chronic studies, in conjuction with the more extensive acute toxicity testing (Passino and Smith 1987; Perry and Smith 1988; Smith et al. 1988), provided a relatively quick but thorough toxicological assessment of a large array of chemicals and demonstrated the relative importance of different classes of compounds in changing growth and survival trends in given populations of native organisms. Classic toxicity tests continue to provide a reliable backdrop of results with which the effects of new chemicals or mixtures can be compared.

  18. Contaminant driven genetic erosion: a case study with Daphnia longispina.

    PubMed

    Ribeiro, Rui; Baird, Donald J; Soares, Amadeu M V M; Lopes, Isabel

    2012-05-01

    Natural populations exposed to pollutants are predicted to experience a loss of genetic diversity, especially through genetic drift, gene flow (emigration), and/or selection (as sensitive genotypes may be lost). In the present study, the authors discuss the use of selectable markers and neutral markers to evaluate a contaminant-driven loss of genetic diversity and possible implications of genetic erosion on populations' viability. Viability could be reduced by altering life history parameters, especially due to fitness costs associated with the acquisition of resistance and/or by compromising the resilience and adaptation to future environmental changes. This discussion aims at an integrated and critical analysis of this topic; it is illustrated by several independent studies (each with its own specific objectives) that were carried out at the same location with Daphnia longispina populations. To the best of the authors' knowledge, this is the most extensively documented case study on genetic erosion of a natural zooplankton population. Directional selection has been found to be a main factor of microevolution; therefore, genetic erosion was detected by monitoring suitable phenotypic markers. Genetic drift was found to be probably irrelevant or masked by other factors, especially gene flow. Although the acquisition of resistance apparently did not entail genetically determined fitness costs under uncontaminated conditions, the present case study suggests the possibility of a further loss of genotypes due to some negative linkages between the sensitivity to potential ulterior toxicants.

  19. Inferred effects of lake acidification on Daphnia galeata mendotae

    SciTech Connect

    Keller, W. ); Yan, N.D.; Holtze, K.E. ); Pitblado, J.R. )

    1990-08-01

    Large numbers of Canadian Shield lakes have been acidified by the atmospheric deposition of anthropogenic sulfur. Biological damage attributable to acidification occurs at all levels of aquatic food webs; however, documentation of this damage has largely been confined to areas near large point sources of air pollutants, to small numbers of study lakes, or to experimentally acidified lakes. Demonstrations of widespread biological effects of acidification have been greatly hampered by the general absence of observations of the occurrence or abundance of important, ubiquitous species in large numbers of lakes ranging widely in acidity, coupled with laboratory determinations of lethal acid thresholds for these species. In consequence, it has been necessary to estimate rather than to document the regional extent of biological damage in North America. In this report the authors couple determination of the lethal acid threshold of Daphnia galeata mendotae Birge, a large, ubiquitous, planktonic crustacean, with results of extensive lake surveys, to examine if the acidification of lakes in Ontario has resulted in widespread losses of this important member of the zooplankton.

  20. Multixenobiotic resistance efflux activity in Daphnia magna and Lumbriculus variegatus.

    PubMed

    Vehniäinen, Eeva-Riikka; Kukkonen, Jussi V K

    2015-04-01

    Multixenobiotic resistance is a phenomenon in which ATP-binding cassette (ABC) family proteins transfer harmful compounds out of cells. Daphnia magna and Lumbriculus variegatus are model species in aquatic ecotoxicology, but the presence and activity of ABC proteins have not been well described in these species. The aim of this work was to study the presence, activity, and inhibition of ABC transport proteins in D. magna and L. variegatus. The presence of abcb1 and abcc transcripts in 8-9-day-old D. magna was investigated by qRT-PCR. The activity of MXR in D. magna and L. variegatus was explored by influx of the fluorescent ABC protein substrates rhodamine B and calcein-AM, with and without the model inhibitors verapamil (unspecific ABC inhibitor), reversin 205 (ABCB1 inhibitor) and MK571 (ABCC inhibitor). Juvenile D. magna possessed all examined abcb and abcc transcripts, but only reversin 205 inhibited MXR activity. The MXR activity in L. variegatus was inhibited by MK571, and to a lesser extent by verapamil, whereas reversin 205 seemed to stimulate the transport activity. Whereas calcein-AM worked better as an MXR substrate in D. magna, rhodamine B was a better substrate for L. variegatus MXR activity measurements. This is the first report on MXR activity in the order Lumbriculida, subclass Oligochaeta, and class Clitellata.

  1. Acute toxicity of 50 metals to Daphnia magna.

    PubMed

    Okamoto, Akira; Yamamuro, Masumi; Tatarazako, Norihisa

    2015-07-01

    Metals are essential for human life and physiological functions but may sometimes cause disorders. Therefore, we conducted acute toxicity testing of 50 metals in Daphnia magna: EC50s of seven elements (Be, Cu, Ag, Cd, Os, Au and Hg) were < 100 µg l(-1) ; EC50s of 13 elements (Al, Sc, Cr, Co, Ni, Zn, Se, Rb, Y, Rh, Pt, Tl and Pb) were between 100 and 1000 µg l(-1) ; EC50s of 14 elements (Li, V, Mn, Fe, Ge, As, In, Sn, Sb, Te, Cs, Ba, W and Ir) were between 1,001 and 100,000 µg l(-1) ; EC50s of six elements (Na, Mg, K, Ca, Sr and Mo) were > 100,000 µg l(-1) ; and. 7 elements (Ti, Zr, Bi, Nb, Hf, Re and Ta) did not show EC50 at the upper limit of respective aqueous solubility, and EC50s were not obtained. Ga, Ru and Pd adhered to the body of D. magna and physically retarded the movement of D. magna. These metals formed hydroxides after adjusting the pH. Therefore, here, we distinguished this physical effect from the physiological toxic effect. The acute toxicity results of 40 elements obtained in this study were not correlated with electronegativity. Similarly, the acute toxicity results of metals including the rare metals were also not correlated with first ionization energy, atomic weight, atomic number, covalent radius, atomic radius or ionic radius.

  2. Aquatic acute toxicity assessments of molybdenum (+VI) to Daphnia magna.

    PubMed

    Wang, Chi-Wei; Liang, Chenju; Yeh, Hui-Ju

    2016-03-01

    Generally, molybdenum (Mo) metals in the environment are very rare, but wastewater discharges from industrial processes may contain high concentrations of Mo, which has the potential to contaminate water or soil if not handled properly. In this study, the impact of three common compounds of hexavalent Mo (sodium molybdate (Na2MoO4‧2H2O), ammonium molybdate ((NH4)6Mo7O24‧4H2O) and molybdenum trioxide (MoO3)) in an aquatic system were assessed based on 48-h exposure acute toxicity to Daphnia magna (D. magna). The LC50 toxicities for associated conjugate ions including Na(+), Cl(-), SO4(2-), and NH4(+) were determined. Furthermore, the LC50 values for the three forms of hexavalent Mo were determined, and the acute toxicities of the Mo forms were found to follow the order: (NH4)6Mo7O24‧4H2O > MoO3 > Na2MoO4‧2H2O in solution. (NH4)6Mo7O24‧4H2O exhibited the lowest LC50 of 43.3 mg L(-1) (corresponding to 23.5 mg Mo L(-1)) among the three molybdenum salts. The research confirmed that the toxicity of molybdenum in the aquatic system is highly dependent on the form of molybdenum salts used, and is also associated with the influence of the background water quality.

  3. Molecular impact of juvenile hormone agonists on neonatal Daphnia magna.

    PubMed

    Toyota, Kenji; Kato, Yasuhiko; Miyakawa, Hitoshi; Yatsu, Ryohei; Mizutani, Takeshi; Ogino, Yukiko; Miyagawa, Shinichi; Watanabe, Hajime; Nishide, Hiroyo; Uchiyama, Ikuo; Tatarazako, Norihisa; Iguchi, Taisen

    2014-05-01

    Daphnia magna has been used extensively to evaluate organism- and population-level responses to pollutants in acute toxicity and reproductive toxicity tests. We have previously reported that exposure to juvenile hormone (JH) agonists results in a reduction of reproductive function and production of male offspring in a cyclic parthenogenesis, D. magna. Recent advances in molecular techniques have provided tools to understand better the responses to pollutants in aquatic organisms, including D. magna. DNA microarray was used to evaluate gene expression profiles of neonatal daphnids exposed to JH agonists: methoprene (125, 250 and 500 ppb), fenoxycarb (0.5, 1 and 2 ppb) and epofenonane (50, 100 and 200 ppb). Exposure to these JH analogs resulted in chemical-specific patterns of gene expression. The heat map analyses based on hierarchical clustering revealed a similar pattern between treatments with a high dose of methoprene and with epofenonane. In contrast, treatment with low to middle doses of methoprene resulted in similar profiles to fenoxycarb treatments. Hemoglobin and JH epoxide hydrolase genes were clustered as JH-responsive genes. These data suggest that fenoxycarb has high activity as a JH agonist, methoprene shows high toxicity and epofenonane works through a different mechanism compared with other JH analogs, agreeing with data of previously reported toxicity tests. In conclusion, D. magna DNA microarray is useful for the classification of JH analogs and identification of JH-responsive genes.

  4. Acute toxicities of six manufactured nanomaterial suspensions to Daphnia magna

    NASA Astrophysics Data System (ADS)

    Zhu, Xiaoshan; Zhu, Lin; Chen, Yongsheng; Tian, Shengyan

    2009-01-01

    The rapid growth of nanotechnology is stimulating research on the potential environmental impacts of manufactured nanomaterials (MNMs). This paper summarizes a comprehensive study on the 48-h acute toxicity of water suspensions of six MNMs (i.e., ZnO, TiO2, Al2O3, C60, SWCNTs, and MWCNTs) to Daphnia magna, using immobilization and mortality as toxicological endpoints. The results show that the acute toxicities of all MNMs tested are dose dependent. The EC50 values for immobilization ranged from 0.622 mg/L (ZnO NPs) to 114.357 mg/L (Al2O3 NPs), while the LC50 values for mortality ranged from 1.511 mg/L (ZnO NPs) to 162.392 mg/L (Al2O3 NPs). In these tests, TiO2, Al2O3, and carbon-based nanomaterials were more toxic than their bulk counterparts. Moreover, D. magna were found to ingest nanomaterials from the test solutions through feeding behaviors, which indicates that the potential ecotoxicities and environmental health effects of these MNMs cannot be neglected.

  5. Increasing toxicity of enrofloxacin over four generations of Daphnia magna.

    PubMed

    Dalla Bona, Mirco; Lizzi, Francesca; Borgato, Arianna; De Liguoro, Marco

    2016-10-01

    The effects of both continuous and alternate exposure to 2mgL(-1) of enrofloxacin (EFX) on survival, growth and reproduction were evaluated over four generations of Daphnia magna. Mortality increased, reaching 100% in most groups by the end of the third generation. Growth inhibition was detected in only one group of the fourth generation. Reproduction inhibition was >50% in all groups and, in second and third generations, groups transferred to pure medium showed a greater inhibition of reproduction than those exposed to EFX. To verify whether the effects observed in these groups could be explained by the perinatal exposure to the antibacterial, a reproduction test with daphnids obtained from in vitro exposed D. magna embryos was also carried out. Perinatal exposure to EFX seemed to act as an 'all-or-nothing' toxicity effect as 31.4% of embryos died, but the surviving daphnids did not show any inhibition of reproduction activity. However, the embryonic mortality may at least partially justify the inhibition of reproduction observed in exposed groups along the multigenerational test. Concluding, the multigenerational test with D. magna did show disruption to a population that cannot be evidenced by the official tests. The increasing deterioration across generations might be inferred as the consequence of heritable alterations. Whilst the concentration tested was higher than those usually detected in the natural environment, the increasing toxicity of EFX across generations and the possible additive toxicity of fluoroquinolone mixtures, prevent harm to crustacean populations by effects in the real context from being completely ruled out.

  6. The heart of Daphnia magna: effects of four cardioactive drugs.

    PubMed

    Villegas-Navarro, Arturo; Rosas-L, Esperanza; Reyes, José L

    2003-10-01

    We used Daphnia magna bioassays to determine the LC(50) and the effects on the heart of the cardioactive drugs ouabain, verapamil, metaproterenol and metoprolol. Distinctions were made between the pharmacological and toxicological effects of these drugs and the adequacy of physicochemical characteristics of its habitat (reconstituted water). Video microscopy and digital image processing were used to study the pharmacological effects on the heart. D. magna exhibited the expected sensitivity to the reference toxicant sodium dodecyl sulfate with a LC(50) of 15.6+/-4.5 mg/l. All drugs were toxic with 48 h-LC(50) of 2.03 mg/l ouabain, 7.04 mg/l verapamil, 32.45 mg/l metaproterenol and 76.21 mg/l metoprolol. Ouabain was the most toxic and caused a positive concentration-dependent inotropic effect. Verapamil caused positive chronotropic and inotropic effects, while metaproterenol showed positive concentration-dependent chronotropic effects at high concentrations (10(-3) and 10(-4) M). Metoprolol induced a positive chronotropic effect at low concentrations (10(-8), 10(-7), 10(-6) M) and a negative chronotropic effect at high concentration (10(-4) M). Ouabain, metaproterenol and metoprolol in D. magna caused similar effects to those produced in mammals. In contrast, verapamil caused opposite effects. The results suggest the presence of Na(+), K(+)-ATPase receptors to verapamil and of non-specific adrenergic receptors in heart of D. magna.

  7. Mixture toxicity of flubendazole and fenbendazole to Daphnia magna.

    PubMed

    Puckowski, Alan; Stolte, Stefan; Wagil, Marta; Markiewicz, Marta; Łukaszewicz, Paulina; Stepnowski, Piotr; Białk-Bielińska, Anna

    2017-02-03

    Nowadays, residual amounts of many pharmaceuticals can be found in various environmental compartments including surface and ground waters, soils and sediments as well as biota. Even though they undergo degradability, their environmental discharge is relatively continuous, thus they may be regarded as quasi-persistent contaminants, and are also frequently regarded as emerging organic pollutants. Benzimidazoles, especially flubendazole (FLU) and fenbendazole (FEN), represent two anthelmintic drugs belonging to this group. Although their presence in environmental matrices has been reported, there is relatively little data concerning their (eco)toxicological impact. Furthermore, no data is available on their mixture toxicity. FLU and FEN have been found to have a strong impact on an environmentally important non-target organism - Daphnia magna. Moreover, these compounds are usually present in the environment as a part of pharmaceutical mixtures. Therefore, there is a need to evaluate their mixture toxicity, which was the main aim of this study. Single substance toxicity tests were carried out in parallel with mixture studies of FLU and FEN, with the application of two well established concepts of Concentration Addition (CA) and Independent Action (IA). As a result, both models (CA and IA) were found to underestimate the toxicity of mixtures, however CA yielded more accurate predictions.

  8. Sublethal effects of phenanthrene, nicotine, and pinane on Daphnia pulex

    SciTech Connect

    Savino, J.F.; Tanabe, L.L. )

    1989-05-01

    Nearly 500 compounds were detected in the tissues of Great Lakes fish as compared to 8 in tissues of hatchery-reared fish. Lethal concentrations for many representative compounds were determined by testing their acute toxicity (48-hr EC50) to Daphnia pulex. However, the population growth and survival of aquatic organisms over longer time intervals are usually affected at concentrations much lower than the EC50 for a specific chemical. To develop a general relationship between acute and chronic concentrations for representative compounds detected in Great Lakes fish, the authors initiated full-life-cycle testing on D. pulex with phenanthrene, nicotine, and pinane. Growth and fecundity of daphnids was measured in 16-d tests in the laboratory. Phenanthrene and nicotine were highly toxic and pinane was moderately toxic to D. pulex in acute studies. For phenanthrene, a compound of the polycyclic aromatic hydrocarbons (PAHs) that has been associated with incomplete combustion of organic matter. For nicotine, a compound in the heterocyclic nitrogen class of chemicals that has been used as an insecticide, the EC50 was 0.24 mg/L. Cyclic alkanes, many of which are constituents of crude oil were represented by pinane for which the EC50 was 3.35 mg/L.

  9. [Acute toxicity of different type pesticide surfactants to Daphnia magna].

    PubMed

    Li, Xiu-huan; Li, Hua; Chen, Cheng-yu; Li, Jian-tao; Liu, Feng

    2013-08-01

    By using the standard test methods in Experimental Guideline for Environmental Safety Evaluation of Chemical Pesticide to aquatic organisms, a comparative study was conducted on the acute toxicity of 39 nonionic, 6 anionic, and 3 cationic surfactants to Daphnia magna. The acute toxicity of three cationic surfactants 1427, 1227 and C8-10 to D. magna belonged to virulent level, and the toxicity of 1427 was the highest, with the EC50 value being 0.97 x 10(-2) mg x L(-1). The acute toxicity of nonionic surfactants polyoxyethylene ether castor oil EL, Tween, and Span emulsifiers belonged to low level, but the toxicity of alkylphenol polyoxyethylene ether and fatty alcohol polyoxyethylene ether surfactants was relatively high, of which, AEO-7 and AEO-5 displayed high toxicity, with the EC50 value being 0.82 and 0.97 mg x L(-1), respectively. In these surfactants, the more liposolubility, the higher the toxicity was. Most of the anionic surfactants were medium in toxicity, but the acute toxicity of NNO belonged to high toxicity, with the EC50 value being 0.17 mg x L(-1).

  10. Fecundity compensation and tolerance to a sterilizing pathogen in Daphnia.

    PubMed

    Vale, P F; Little, T J

    2012-09-01

    Hosts are armed with several lines of defence in the battle against parasites: they may prevent the establishment of infection, reduce parasite growth once infected or persevere through mechanisms that reduce the damage caused by infection, called tolerance. Studies on tolerance in animals have focused on mortality, and sterility tolerance has not been investigated experimentally. Here, we tested for genetic variation in the multiple steps of defence when the invertebrate Daphnia magna is infected with the sterilizing bacterial pathogen Pasteuria ramosa: anti-infection resistance, anti-growth resistance and the ability to tolerate sterilization once infected. When exposed to nine doses of a genetically diverse pathogen inoculum, six host genotypes varied in their average susceptibility to infection and in their parasite loads once infected. How host fecundity changed with increasing parasite loads did not vary between genotypes, indicating that there was no genetic variation for this measure of fecundity tolerance. However, genotypes differed in their level of fecundity compensation under infection, and we discuss how, by increasing host fitness without targeting parasite densities, fecundity compensation is consistent with the functional definition of tolerance. Such infection-induced life-history shifts are not traditionally considered to be part of the immune response, but may crucially reduce harm (in terms of fitness loss) caused by disease, and are a distinct source of selection on pathogens.

  11. Fecundity compensation and tolerance to a sterilizing pathogen in Daphnia

    PubMed Central

    Vale, P F; Little, T J

    2012-01-01

    Hosts are armed with several lines of defence in the battle against parasites: they may prevent the establishment of infection, reduce parasite growth once infected or persevere through mechanisms that reduce the damage caused by infection, called tolerance. Studies on tolerance in animals have focused on mortality, and sterility tolerance has not been investigated experimentally. Here, we tested for genetic variation in the multiple steps of defence when the invertebrate Daphnia magna is infected with the sterilizing bacterial pathogen Pasteuria ramosa: anti-infection resistance, anti-growth resistance and the ability to tolerate sterilization once infected. When exposed to nine doses of a genetically diverse pathogen inoculum, six host genotypes varied in their average susceptibility to infection and in their parasite loads once infected. How host fecundity changed with increasing parasite loads did not vary between genotypes, indicating that there was no genetic variation for this measure of fecundity tolerance. However, genotypes differed in their level of fecundity compensation under infection, and we discuss how, by increasing host fitness without targeting parasite densities, fecundity compensation is consistent with the functional definition of tolerance. Such infection-induced life-history shifts are not traditionally considered to be part of the immune response, but may crucially reduce harm (in terms of fitness loss) caused by disease, and are a distinct source of selection on pathogens. PMID:22856460

  12. A New Reference Genome Assembly for the Microcrustacean Daphnia pulex.

    PubMed

    Ye, Zhiqiang; Xu, Sen; Spitze, Ken; Asselman, Jana; Jiang, Xiaoqian; Ackerman, Matthew S; Lopez, Jacqueline; Harker, Brent; Raborn, R Taylor; Thomas, W Kelley; Ramsdell, Jordan; Pfrender, Michael E; Lynch, Michael

    2017-02-24

    Comparing genomes of closely related genotypes from populations with distinct demographic histories can help reveal the impact of effective population size on genome evolution. For this purpose, we present a high-quality genome assembly of Daphnia pulex (PA42), and compare this with the first sequenced genome of this species (TCO), which was derived from an isolate from a population with >90% reduction in nucleotide diversity. PA42 has numerous similarities to TCO at the gene level, with an average amino-acid sequence identity of 98.8% and >60% of orthologous proteins identical. Nonetheless, there is a highly elevated number of genes in the TCO genome annotation, with ~7,000 excess genes appearing to be false positives. This view is supported by the high GC content, lack of introns, and short length of these suspicious gene annotations. Consistent with the view that reduced effective population size can facilitate the accumulation of slightly deleterious genomic features, we observe more proliferation of transposable elements and a higher frequency of gained introns in the TCO genome.

  13. Genotype × genotype interactions between the toxic cyanobacterium Microcystis and its grazer, the waterflea Daphnia

    PubMed Central

    Lemaire, Veerle; Brusciotti, Silvia; van Gremberghe, Ineke; Vyverman, Wim; Vanoverbeke, Joost; De Meester, Luc

    2012-01-01

    Toxic algal blooms are an important problem worldwide. The literature on toxic cyanobacteria blooms in inland waters reports widely divergent results on whether zooplankton can control cyanobacteria blooms or cyanobacteria suppress zooplankton by their toxins. Here we test whether this may be due to genotype × genotype interactions, in which interactions between the large-bodied and efficient grazer Daphnia and the widespread cyanobacterium Microcystis are not only dependent on Microcystis strain or Daphnia genotype but are specific to genotype × genotype combinations. We show that genotype × genotype interactions are important in explaining mortality in short-time exposures of Daphnia to Microcystis. These genotype × genotype interactions may result in local coadaptation and a geographic mosaic of coevolution. Genotype × genotype interactions can explain why the literature on zooplankton–cyanobacteria interactions is seemingly inconsistent, and provide hope that zooplankton can contribute to the suppression of cyanobacteria blooms in restoration projects. PMID:25568039

  14. Male meiosis in Crustacea: synapsis, recombination, epigenetics and fertility in Daphnia magna.

    PubMed

    Gómez, Rocío; Van Damme, Kay; Gosálvez, Jaime; Morán, Eugenio Sánchez; Colbourne, John K

    2016-09-01

    We present the first detailed cytological study of male meiosis in Daphnia (Crustacea: Branchiopoda: Cladocera)-an aquatic microcrustacean with a cyclical parthenogenetic life cycle. Using immunostaining of the testes in Daphnia magna for baseline knowledge, we characterized the different stages of meiotic division and spermiogenesis in relation to the distribution of proteins involved in synapsis, early recombination events and sister chromatid cohesion. We also studied post-translational histone modifications in male spermatocytes, in relation to the dynamic chromatin progression of meiosis. Finally, we applied a DNA fragmentation test to measure sperm quality of D. magna, with respect to levels of inbreeding. As a proxy for fertility, this technique may be used to assess the reproductive health of a sentinel species of aquatic ecosystems. Daphnia proves to be a model species for comparative studies of meiosis that is poised to improve our understanding of the cytological basis of sexual and asexual reproduction.

  15. Gene transcription in Daphnia magna: effects of acute exposure to a carbamate insecticide and an acetanilide herbicide.

    PubMed

    Pereira, Joana Luísa; Hill, Christopher J; Sibly, Richard M; Bolshakov, Viacheslav N; Gonçalves, Fernando; Heckmann, Lars-Henrik; Callaghan, Amanda

    2010-05-05

    Daphnia magna is a key invertebrate in the freshwater environment and is used widely as a model in ecotoxicological measurements and risk assessment. Understanding the genomic responses of D. magna to chemical challenges will be of value to regulatory authorities worldwide. Here we exposed D. magna to the insecticide methomyl and the herbicide propanil to compare phenotypic effects with changes in mRNA expression levels. Both pesticides are found in drainage ditches and surface water bodies standing adjacent to crops. Methomyl, a carbamate insecticide widely used in agriculture, inhibits acetylcholinesterase, a key enzyme in nerve transmission. Propanil, an acetanilide herbicide, is used to control grass and broad-leaf weeds. The phenotypic effects of single doses of each chemical were evaluated using a standard immobilisation assay. Immobilisation was linked to global mRNA expression levels using the previously estimated 48h-EC(1)s, followed by hybridization to a cDNA microarray with more than 13,000 redundant cDNA clones representing >5000 unique genes. Following exposure to methomyl and propanil, differential expression was found for 624 and 551 cDNAs, respectively (one-way ANOVA with Bonferroni correction, P

  16. Single- and mixture toxicity of three organic UV-filters, ethylhexyl methoxycinnamate, octocrylene, and avobenzone on Daphnia magna.

    PubMed

    Park, Chang-Beom; Jang, Jiyi; Kim, Sanghun; Kim, Young Jun

    2017-03-01

    In freshwater environments, aquatic organisms are generally exposed to mixtures of various chemical substances. In this study, we tested the toxicity of three organic UV-filters (ethylhexyl methoxycinnamate, octocrylene, and avobenzone) to Daphnia magna in order to evaluate the combined toxicity of these substances when in they occur in a mixture. The values of effective concentrations (ECx) for each UV-filter were calculated by concentration-response curves; concentration-combinations of three different UV-filters in a mixture were determined by the fraction of components based on EC25 values predicted by concentration addition (CA) model. The interaction between the UV-filters were also assessed by model deviation ratio (MDR) using observed and predicted toxicity values obtained from mixture-exposure tests and CA model. The results from this study indicated that observed ECxmix (e.g., EC10mix, EC25mix, or EC50mix) values obtained from mixture-exposure tests were higher than predicted ECxmix (e.g., EC10mix, EC25mix, or EC50mix) values calculated by CA model. MDR values were also less than a factor of 1.0 in a mixtures of three different UV-filters. Based on these results, we suggest for the first time a reduction of toxic effects in the mixtures of three UV-filters, caused by antagonistic action of the components. Our findings from this study will provide important information for hazard or risk assessment of organic UV-filters, when they existed together in the aquatic environment. To better understand the mixture toxicity and the interaction of components in a mixture, further studies for various combinations of mixture components are also required.

  17. Toxic effects of diclofenac on life history parameters and the expression of detoxification-related genes in Daphnia magna.

    PubMed

    Liu, Yang; Wang, Lan; Pan, Benben; Wang, Chao; Bao, Shuang; Nie, Xiangping

    2017-02-01

    Diclofenac (DCF), as a widely used drug, has been detected in various environmental media such as municipal wastewater effluent. However, there is little information on the effects of DCF on freshwater invertebrates potentially exposing to its residues in surface water. In the present study, we investigated the toxic effects of DCF on the physiological parameters (e.g., survival, growth rate, and reproduction) of a crustacean, Daphnia magna, via a 21-d chronic toxicity test, and we also evaluated the effects of DCF on the expression of the genes related to the detoxification metabolism, growth, development and reproduction (e.g., HR96, P-gp, CYP360A8, CYP314, GST, EcR and Vtg) in acute exposure (up to 96h) with RT-PCR. Significant toxic effects of DCF to D. magna were observed at 50μgL(-1), the expression of these selected genes was inhibited with 24h of exposure, and induced after 48h to some extents. The expression of Vtg was induced at high concentrations of DCF (500μgL(-1) and 5000μgL(-1)) after 24h and 48h of exposure, but also significantly induced at low concentration (50μgL(-1)) after 96h of exposure. Dose- and time-dependent relationships were observed for gene expression of the seven selected genes. In the 21-d chronic toxicity test, the days to the first brood and the days to the first egg production were both significantly delayed at 50μgL(-1). However, there were no significant differences observed among the molting frequency, number of eggs produced in the first brood, total number of eggs per individual, total number of broods per individual, body length and intrinsic growth rate. Our results suggested that the reproduction parameters are more sensitive endpoints than the survival and growth for evaluating the toxicity of DCF to aquatic invertebrates.

  18. Biological surface coating and molting inhibition as mechanisms of TiO2 nanoparticle toxicity in Daphnia magna.

    PubMed

    Dabrunz, André; Duester, Lars; Prasse, Carsten; Seitz, Frank; Rosenfeldt, Ricki; Schilde, Carsten; Schaumann, Gabriele E; Schulz, Ralf

    2011-01-01

    The production and use of nanoparticles (NP) has steadily increased within the last decade; however, knowledge about risks of NP to human health and ecosystems is still scarce. Common knowledge concerning NP effects on freshwater organisms is largely limited to standard short-term (≤48 h) toxicity tests, which lack both NP fate characterization and an understanding of the mechanisms underlying toxicity. Employing slightly longer exposure times (72 to 96 h), we found that suspensions of nanosized (∼100 nm initial mean diameter) titanium dioxide (nTiO(2)) led to toxicity in Daphnia magna at nominal concentrations of 3.8 (72-h EC(50)) and 0.73 mg/L (96-h EC(50)). However, nTiO(2) disappeared quickly from the ISO-medium water phase, resulting in toxicity levels as low as 0.24 mg/L (96-h EC(50)) based on measured concentrations. Moreover, we showed that nTiO(2) (∼100 nm) is significantly more toxic than non-nanosized TiO(2) (∼200 nm) prepared from the same stock suspension. Most importantly, we hypothesized a mechanistic chain of events for nTiO(2) toxicity in D. magna that involves the coating of the organism surface with nTiO(2) combined with a molting disruption. Neonate D. magna (≤6 h) exposed to 2 mg/L nTiO(2) exhibited a "biological surface coating" that disappeared within 36 h, during which the first molting was successfully managed by 100% of the exposed organisms. Continued exposure up to 96 h led to a renewed formation of the surface coating and significantly reduced the molting rate to 10%, resulting in 90% mortality. Because coating of aquatic organisms by manmade NP might be ubiquitous in nature, this form of physical NP toxicity might result in widespread negative impacts on environmental health.

  19. Toxicity of two fungicides in Daphnia: is it always temperature-dependent?

    PubMed

    Cuco, Ana P; Abrantes, Nelson; Gonçalves, Fernando; Wolinska, Justyna; Castro, Bruno B

    2016-09-01

    The joint effect of increasing temperature and pollution on aquatic organisms is important to understand and predict, as a combination of stressors might be more noxious when compared to their individual effects. Our goal was to determine the sensitivity of a model organism (Daphnia spp.) to contaminants at increasing temperatures, allowing prior acclimation of the organisms to the different temperatures. Prior to exposure, two Daphnia genotypes (Daphnia longispina species complex) were acclimated to three temperatures (17, 20, and 23 °C). Afterwards, a crossed design was established using different exposure temperatures and a range of concentrations of two common fungicides (tebuconazole and copper). Daphnia life history parameters were analysed in each temperature × toxicant combination for 21 days. Temperature was the most influencing factor: Daphnia reproduced later and had lower fecundity at 17 °C than at 20 and 23 °C. Both copper and tebuconazole also significantly reduced the fecundity and survival of Daphnia at environmentally-relevant concentrations. Temperature-dependence was found for both toxicants, but the response pattern was endpoint- and genotype-specific. The combination of contaminant and high temperature often had severe effects on survival. However, unlike some literature on the subject, our results do not support the theory that increasing temperatures consistently foment increasing reproductive toxicity. The absence of a clear temperature-dependent toxicity pattern may result from the previous acclimation to the temperature regime. However, a proper framework is lacking to compare such studies and to avoid misleading conclusions for climate change scenarios.

  20. Optimization of mRNA design for protein expression in the crustacean Daphnia magna.

    PubMed

    Törner, Kerstin; Nakanishi, Takashi; Matsuura, Tomoaki; Kato, Yasuhiko; Watanabe, Hajime

    2014-08-01

    The water flea Daphnia is a new model organism for ecological, evolutionary, and toxicological genomics. Detailed functional analysis of genes newly discovered through genomic approaches often requires overexpression of the identified protein. In the present study, we report the microinjection of in vitro-synthesized RNAs into the eggs as a method for overexpressing ubiquitous proteins in Daphnia magna. We injected a 1.3-kb mRNA that coded for the red fluorescent protein (DsRed2) flanked by UTRs from the ubiquitously expressed elongation factor 1α-1 (EF1α-1) into D. magna embryos. DsRed2 fluorescence in the embryos was measured 24 h after microinjection. Unexpectedly, the reporter RNA containing the 522-bp full-length EF1α-1 3' UTR failed to induce fluorescence. To assess reporter expression, the length of the 3' UTR that potentially contained negative regulatory elements of protein expression, including AU-rich regions and Musashi binding elements, was serially reduced from the 3' end. Assessing all injected RNA alternatives, mRNA containing the first 60 bp of the 3' UTR gave rise to the highest fluorescence, 14 times the Daphnia auto-fluorescence. In contrast, mRNA lacking the entire 3' UTR hardly induced any change in fluorescence intensity. This is the first evaluation of UTRs of mRNAs delivered into Daphnia embryos by microinjection for overexpressing proteins. The mRNA with truncated 3' UTRs of Daphnia EF1α-1 will be useful not only for gain-of-function analyses but also for labeling proteins and organelles with fluorescent proteins in Daphnia.

  1. Competition impedes the recovery of Daphnia magna from repeated insecticide pulses.

    PubMed

    Dolciotti, Ida; Foit, Kaarina; Herkelrath, Anna; Liess, Matthias

    2014-02-01

    The effects of multiple insecticide pulses on non-target organisms have rarely been investigated in combination with relevant biotic interactions, such as competition. In this study, we examined the effects of two repeated pulses of the insecticide pirimicarb (3, 10, 24 μg/L) on populations of Daphnia magna with or without competition. To investigate the influence of competition, half of the test systems were supplemented with the pirimicarb-insensitive species Culex pipiens. The pesticide pulses were followed by a recovery period of 28 days, which corresponded to approximately three generation times for D. magna. The one-species setup with the Daphnia populations and the two-species setup with both the Daphnia and Culex populations had a precontamination period of 30 days so that intra- and interspecific competitions were present prior to the insecticide pulse. Short-term effects on the survival of the Daphnia population were observed in both setups immediately after each insecticide pulse at the highest concentration level. In the one-species setup, the short-term effects on population survival were increased by intraspecific competition. However, the Daphnia populations in the one-species setup recovered and reached the control level within approximately two weeks after each insecticide pulse. In contrast, in the two-species setup at the highest concentration, we observed culmination of insecticide effects: the Daphnia populations did not recover and their abundance was below the control level until the end of the observation time. Their recovery was impeded by the presence of the competing species C. pipiens for at least four weeks. At low concentrations, no culmination of effects was observed. We conclude that repeated toxicant pulses on populations that are challenged with interspecific competition may result in a multigenerational culmination of toxicant effects.

  2. Comparative toxicity of copper and acridine to fish, Daphnia and algae

    SciTech Connect

    Blaylock, B.G.; Frank, M.L.; McCarthy, J.F.

    1985-01-01

    A comparison was made of the sensitivity of fish, Daphnia and algae to the toxic effects of copper and acridine. A series of toxicity tests was conducted with these organisms, and the following biological endpoints determined: LC50s for fish, LC50s and effects on reproduction of Daphnia and 50% inhibition of the growth rate of algae. The 96-h LCO50s for bluegill (Lepomis macrochirus) and Daphnia magna exposed to copper were 2.2 and 0.13 mg/L, respectively. A chronic exposure to 0.03 mg/L of copper for 14 d significantly decreased reproduction in Daphnia. Exposure to 0.4 and 0.2 mg/L copper inhibited the growth rate of Selenastrum capricornutum and Chlorella vulgaris, respectively, by 50%. The 96-h LC50s for fathead minnows (Pimephales promelas) and D. magna exposed to acridine were 2.3 and 3.1 mg/L, respectively. A chronic exposure to 1.25 mg/L acridine for 14 d significantly inhibited reproduction in Daphnia, and an exposure to 0.9 mg/L inhibited the growth rate of S. capricornutum by 50%. Based on the biological endpoints determined in these tests, Daphnia were more sensitive to copper than were fish or algae. In contrast, the most sensitive biological endpoint in tests with acridine was the inhibition of algal growth. Comparison of these test results indicates that short-term toxicity tests used for screening toxicants for possible environmental effects should include both plant and animal species. 16 references, 4 figures, 4 tables.

  3. Ecotoxicological effects of jute retting on the survival of two freshwater fish and two invertebrates.

    PubMed

    Mondal, Debjit Kumar; Kaviraj, Anilava

    2008-04-01

    Severe deterioration of water quality occurs during jute retting in ponds, canals, floodplain lakes, and other inland water bodies in the rural areas of West Bengal in India. Attempts were made to evaluate changes in the physicochemical parameters of water caused by jute retting, and their impact on the survival of two species of freshwater fish (Labeo rohita and Hypophthalmicthys molitrix) and two species of freshwater invertebrate (Daphnia magna, a Cladocera, and Branchiura sowerbyi, an Oligochaeta). Results showed that jute retting in a pond for 30 days resulted in a sharp increase in the BOD (>1,000 times) and COD (>25 times) of the water, along with a sharp decrease in dissolved oxygen (DO). Free CO(2), total ammonia, and nitrate nitrogen also increased (three to five times) in water as a result of jute retting. Ninety-six-hour static bioassays performed in the laboratory with different dilutions of jute-retting water (JRW) revealed that D. magna and B. sowerbyi were not susceptible to even the raw JRW whereas fingerlings of both species of fish were highly susceptible, L. rohita being more sensitive (96 h LC(50) 37.55% JRW) than H. molitrix (96 h LC(50) 57.54% JRW). Mortality of fish was significantly correlated with the percentage of JRW.

  4. Inhabitants of the Fresh-Water Community.

    ERIC Educational Resources Information Center

    Jorgensen, Joseph; Schroeder, Marlene

    This learner's guide is designed to assist middle school students in studying freshwater organisms. Following a brief introduction to freshwater ecology, simple line drawings facilitate the identification of plants and animals common to Florida's freshwater ecosystems. Emphasis of the short text which accompanies each illustration is upon the…

  5. Effect of hypoxia on sodium and ammonium acetate toxicity for Daphnia.

    PubMed

    Podosynovickova, N P; Schaefer, T V; Rejniuk, V L; Ivnitsky, Ju Ju

    2010-11-01

    Exposure of Daphnia in degassed (boiled) culturing water (hypoxia simulation) led to solitary lethal outcomes after more than 24 h. Before this term, hypoxia had no appreciable effect on the toxicity of sodium or ammonium acetate salts. The sensitivity of daphnias to the lethal effects of the tested chemicals did not change under conditions of normal oxygenation and increased sharply (by two orders of magnitude) under conditions of hypoxia, loosing the linear relationship with toxicant concentration. Ammonium acetate toxicity more markedly increased under conditions of hypoxia than sodium acetate toxicity. These data should be taken into consideration when predicting the results of combined effects of toxicants on water ecosystems and on human organism.

  6. Chronic toxicity of aniline and 2,4-dichlorophenol to Daphnia magna Straus

    SciTech Connect

    Gersich, F.M.; Milazzo, D.P.

    1988-01-01

    Data generated from daphnid chronic toxicity tests are used by various regulatory agencies for the development of water quality criteria. Two chemicals which are lacking reported chronic data are aniline and 2,4-dichlorophenol. The acute toxicity of 2,4-dichlorophenol to Daphnia magna has been reported; the toxicity of aniline to D. magna also has been reported. Chronic data for these chemicals are lacking for invertebrates. The objective of this study was to estimate the chronic toxicity of aniline and 2,4-dichlorophenol to Daphnia magna Straus, using a standard 21-day static renewal procedure.

  7. The potential of TiO2 nanoparticles as carriers for cadmium uptake in Lumbriculus variegatus and Daphnia magna.

    PubMed

    Hartmann, Nanna B; Legros, Samuel; Von der Kammer, Frank; Hofmann, Thilo; Baun, Anders

    2012-08-15

    The use of engineered nanoparticles (e.g. in industrial applications and consumer products) is increasing. Consequently, these particles will be released into the aquatic environment. Through aggregation/agglomeration and sedimentation, sediments are expected ultimately to be sinks for nanoparticles. Both in the water phase and in the sediments engineered nanoparticles will mix and interact with other environmental pollutants, including metals. In this study the toxicity of cadmium to two freshwater organisms, water column crustacean Daphnia magna and sediment oligochaete Lumbriculus variegatus, was investigated both in the absence and presence of titanium dioxide (TiO(2)) nanoparticles (P25 Evonic Degussa, d: 30 nm). The uptake of cadmium in sub-lethal concentrations was also studied in the absence and presence of 2 mg/L TiO(2) nanoparticles. Formation of larger nanoparticles aggregates/agglomerates was observed and sizes varied depending on media composition (358±13 nm in US EPA moderately hard synthetic freshwater and 1218±7 nm in Elendt M7). TiO(2) nanoparticles are potential carriers for cadmium and it was found that 25% and 6% of the total cadmium mass in the test system for L. variegatus and D. magna tests were associated to suspended TiO(2) particles, respectively. μXRF (micro X-ray fluorescence) analysis confirmed the uptake of TiO(2) in the gut of D. magna. For L. variegatus μXRF analysis indicated attachment of TiO(2) nanoparticles to the organism surface as well as a discrete distribution within the organisms. Though exact localisation in this organism was more difficult to assess, the uptake seems to be within the coelomic cavity. Results show that the overall body burden and toxicity of cadmium to L. variegatus was unchanged by addition of TiO(2) nanoparticles, showing that cadmium adsorption to TiO(2) nanoparticles did not affect overall bioavailability. Despite facilitated uptake of cadmium by TiO(2) nanoparticles in D. magna, resulting in

  8. Developmental toxicity, acute toxicity and mutagenicity testing in freshwater snails Biomphalaria glabrata (Mollusca: Gastropoda) exposed to chromium and water samples.

    PubMed

    Tallarico, Lenita de Freitas; Borrely, Sueli Ivone; Hamada, Natália; Grazeffe, Vanessa Siqueira; Ohlweiler, Fernanda Pires; Okazaki, Kayo; Granatelli, Amanda Tosatte; Pereira, Ivana Wuo; Pereira, Carlos Alberto de Bragança; Nakano, Eliana

    2014-12-01

    A protocol combining acute toxicity, developmental toxicity and mutagenicity analysis in freshwater snail Biomphalaria glabrata for application in ecotoxicological studies is described. For acute toxicity testing, LC50 and EC50 values were determined; dominant lethal mutations induction was the endpoint for mutagenicity analysis. Reference toxicant potassium dichromate (K2Cr2O7) was used to characterize B. glabrata sensitivity for toxicity and cyclophosphamide to mutagenicity testing purposes. Compared to other relevant freshwater species, B. glabrata showed high sensitivity: the lowest EC50 value was obtained with embryos at veliger stage (5.76mg/L). To assess the model applicability for environmental studies, influent and effluent water samples from a wastewater treatment plant were evaluated. Gastropod sensitivity was assessed in comparison to the standardized bioassay with Daphnia similis exposed to the same water samples. Sampling sites identified as toxic to daphnids were also detected by snails, showing a qualitatively similar sensitivity suggesting that B. glabrata is a suitable test species for freshwater monitoring. Holding procedures and protocols implemented for toxicity and developmental bioassays showed to be in compliance with international standards for intra-laboratory precision. Thereby, we are proposing this system for application in ecotoxicological studies.

  9. Comparative toxicity of metals to freshwater life in tropical Australia

    SciTech Connect

    Markich, S.J.; Camilleri, C.; Baird, D.J.

    1995-12-31

    At present, there is a paucity of internally consistent datasets on the toxicity of metals (and other contaminants) in the tropics, relative to the cool and warm temperate regions of the world. Such information is considered mandatory before a proper comparison of the toxicity of metals to aquatic life between tropical and temperate regions is possible. As part of a larger study to investigate whether the toxicity of metals to aquatic life differs between the tropical and temperate regions of Australia, several species of tropical freshwater organisms, comprising a molluscs, fish, hydra, Daphnia and an alga were employed to obtain an internally consistent data set on the comparative toxicity of selected metals, such as U and Cu, that are of potential concern in the wet-dry tropics of Australia as a result of man`s activities. Both acute and chronic ecologically relevant sublethal endpoints, such as growth and reproduction (EC{sub 50}, BEC{sub 10}) were measured for the five species, which cover a variety of trophic levels. A synthetic water quality that closely resembled the inorganic composition of the natural waters in which the organisms inhabit, was used in all experiments. This facilitated the use of the geochemical modelling code, HARPHRQ, to predict the speciation, and hence, bioavailability of the selected metals. A knowledge of the bioavailable fraction of a metal is necessary for setting up national water quality guidelines for the protection of aquatic life. The results from this study are discussed and related to the derivation of both site-specific and national water quality-guidelines for metals.

  10. The aquatic impact of ionic liquids on freshwater organisms.

    PubMed

    Costa, Susana P F; Pinto, Paula C A G; Saraiva, M Lúcia M F S; Rocha, Fábio R P; Santos, Joyce R P; Monteiro, Regina T R

    2015-11-01

    Ionic liquids (ILs), also known as liquid electrolytes, are powerful solvents with a wide variety of academic and industrial applications. Bioassays with aquatic organisms constitute an effective tool for the evaluation of ILs' toxicity, as well as for the prediction and identification of possible moieties that act as toxicophores. In this work, the acute toxicity of six ILs and two commonly used organic solvents was evaluated using freshwater organisms: Daphnia magna, Raphidocelis subcapitata and Hydra attenuata. The bioassays were performed by exposing the organisms to increasing concentrations of the ILs and observing D. magna immobilization, R. subcapitata growth inhibition, and the morphological or mortality effects in H. attenuata. The results demonstrate that the tested organisms are not equally susceptible to the ILs, e.g., bmpyr [BF4] was the least toxic compound for R. subcapitata, N1,1 [N1,1,1OOH] for D. magna and emim [Tf2N] for H. attenuata. This highlights the importance of applying a battery of assays in toxicological analysis. Additionally, Hydra proved to be the most tolerant species to the tested ILs. According to their hazard rankings, the tested ILs are considered practically harmless or moderately toxic, except (Hex)3(TDec)P [Cl], which was classified as highly toxic. The ILs were revealed to be more harmful to aquatic systems than the tested organic solvents, reaffirming the need to analyze carefully the (eco)toxicological impact of these compounds. The present study provides additional data in the evaluation of the potential hazard and the impact of ILs in the environment.

  11. Response of planktonic cladocerans (Class: Branchiopoda) to short-term changes in environmental variables in the surface waters of the Bay of Biscay

    NASA Astrophysics Data System (ADS)

    d'Elbée, Jean; Lalanne, Yann; Castège, Iker; Bru, Noelle; D'Amico, Frank

    2014-08-01

    From January 2001 to December 2008, 73 surface plankton samples and 45 vertical profiles of sea temperature, salinity, dissolved oxygen and pH were collected on a monthly basis from a single sampling station located in the Bay of Biscay (43°37N; 1°43W) (North-East Atlantic). Two types of North Atlantic Oscillation (NAO) indexes were included in the data set and submitted to a Canonical Correspondence Analysis and Spearman non-parametric test. Significant breaks and levels in time series were tested using a data segmentation method. The temperature range varies from 11 °C to 25 °C. It begins to rise from April until August and then decline. Low salinity values occur in mid-spring (<34 PSU) and high values (>36 PSU) in autumn. Dissolved oxygen mean values were around 8 mg/l. In summer, when temperature and salinity are high, surface water layer is always accompanied with a significant deoxygenation, and the process reverses in winter. pH mean values range was 7.78-8.33. Seasonal and inter-annual variations of the two NAO indexes are strongly correlated to one another, but do not correlate with any hydrological or biological variable. Five of the seven cladocerans species which are present in the Bay of Biscay were found in this study. There is a strong pattern in species succession throughout the year: Evadne nordmanni is a vernal species, while Penilia avirostris and Pseudevadne tergestina occur mainly in summer and autumn. Evadne spinifera has a maximum abundance in spring, Podon intermedius in autumn, but they both occur throughout the year. However, for some thirty years, the presence of species has tended to become significantly extended throughout the year. During the 2001-2008 period, there was a noticeable decline and even a disappearance of the categories involved in sexual reproduction as well as those involved in parthenogenesis, in favor of non-breeding individuals.

  12. Influence of polychlorinated aromatic compounds on the biotransformation and toxicity of organophosphorus pesticides (OP) to the Daphnia magna

    SciTech Connect

    Tonkopii, V.; Zagrebin, A.; Sherstneva, L.

    1995-12-31

    The effect of different polychlorinated aromatics (DDT, Aroclor 1254, certain polychlorinated biphenyls and dibenzofurans) on the toxicity of OP (DDVP paraoxon, malaoxon) to Daphnia magna was studied. Pretreatment of daphnids with chlorinated compounds during 72 hours in nontoxic concentrations (1/5--1/20 CL{sub 50}) has been shown to reduce the toxicity of OP for hydrobionts. For study of influence of chlorinated compounds on biotransformation of OP the activity of enzymes which are hydrolyzing the OP was investigated in Daphnia`s homogenates or microsomes. The activity of carboxylesterase (tributyrinase, aliesterase) and arylesterase (phosphorylphosphatase) with usage as substrates accordingly {alpha}-naphthylacetate and paraoxon was measured. Besides that the activity of cholinesterase with application of propionylthiocholine as substrate was determined. After polychlorinated aromatic compounds treatment of daphnids activities of both aryl-and carboxylesterase increased markedly. It decreased the inhibition of Daphnia`s cholinesterase caused by incubation with OP in concentrations 0.5--1.0 CL{sub 50}. Thus the induction by chlorinate aromatics of OP metabolizing enzymes seems to play the important role in reduction of OP toxicity to Daphnia magna. Perhaps the aryl- and carboxylesterase of Daphnia can be used as biomarkers of pollution by polychlorinated aromatics in water.

  13. Genes mirror geography in Daphnia magna.

    PubMed

    Fields, Peter D; Reisser, Céline; Dukić, Marinela; Haag, Christoph R; Ebert, Dieter

    2015-09-01

    Identifying the presence and magnitude of population genetic structure remains a major consideration in evolutionary biology as doing so allows one to understand the demographic history of a species as well as make predictions of how the evolutionary process will proceed. Next-generation sequencing methods allow us to reconsider previous ideas and conclusions concerning the distribution of genetic variation, and what this distribution implies about a given species evolutionary history. A previous phylogeographic study of the crustacean Daphnia magna suggested that, despite strong genetic differentiation among populations at a local scale, the species shows only moderate genetic structure across its European range, with a spatially patchy occurrence of individual lineages. We apply RAD sequencing to a sample of D. magna collected across a wide swath of the species' Eurasian range and analyse the data using principle component analysis (PCA) of genetic variation and Procrustes analytical approaches, to quantify spatial genetic structure. We find remarkable consistency between the first two PCA axes and the geographic coordinates of individual sampling points, suggesting that, on a continent-wide scale, genetic differentiation is driven to a large extent by geographic distance. The observed pattern is consistent with unimpeded (i.e. no barriers, landscape or otherwise) migration at large spatial scales, despite the fragmented and patchy nature of favourable habitats at local scales. With high-resolution genetic data similar patterns may be uncovered for other species with wide geographic distributions, allowing an increased understanding of how genetic drift and selection have shaped their evolutionary history.

  14. Bioaccumulation and uptake routes of perfluoroalkyl acids in Daphnia magna.

    PubMed

    Dai, Zhineng; Xia, Xinghui; Guo, Jia; Jiang, Xiaoman

    2013-02-01

    Perfluoroalkyl acids (PFAs), one kind of emerging contaminants, have attracted great attentions in recent years. However, the study about their bioaccumulation mechanism remains scarce. In this research, the bioaccumulation of six kinds of PFAs in water flea Daphnia magna was studied. The uptake rates of PFAs in D. magna ranged from 178 to 1338 L kg(-1) d(-1), and they increased with increasing perfluoroalkyl chain length; the elimination rates ranged from 0.98 to 2.82 d(-1). The bioaccumulation factors (BAFs) of PFAs ranged from 91 to 380 L kg(-1) in wet weight after 25 d exposure; they increased with increasing perfluoroalkyl chain length and had a significant positive correlation with the n-octanol/water partition coefficients (logK(ow)) of PFAs (p<0.05). This indicated that the hydrophobicity of PFAs plays an important role in their bioaccumulation. The BAFs almost kept constant when the PFA concentrations in aqueous phase increased from 1 to 10 μg L(-1). Scenedesmus subspicatus, as the food of D. magna, did not significantly affect the bioaccumulation of PFAs by D. magna. Furthermore, the body burden of PFAs in the dead D. magna was 1.08-2.52 times higher than that in the living ones, inferring that the body surface sorption is a main uptake route of PFAs in D. magna. This study suggested that the bioaccumulation of PFAs in D. magna is mainly controlled by their partition between organisms and water; further research should be conducted to study the intrinsic mechanisms, especially the roles of protein and lipid in organisms.

  15. Comparative toxicity of leachates from 52 textiles to Daphnia magna.

    PubMed

    Dave, Göran; Aspegren, Pia

    2010-10-01

    The environmental aspects of textiles are very complex and include production, processing, transport, usage, and recycling. Textiles are made from a variety of materials and can contain a large number of chemicals. Chemicals are used during production of fibres, for preservation and colouring and they are released during normal wear and during washing. The aim of this study was to investigate the release to water of toxic chemicals from various textiles. Altogether 52 samples of textiles made from cotton (21), linen (4), cotton and linen (7), cellulose (3), synthetic fibres (7), cotton and synthetic fibres (8) and wool (2). Seven were eco-labelled. All textiles were cut into squares and placed into Petri dishes with 50 ml ISO test medium in a concentration series (4-256 cm(2)/50 ml) and tested for acute toxicity to Daphnia magna. Estimated EC50s were converted into weight/volume, and 48-h EC50s ranged between <1 and >182 g/L. It was not possible to detect any difference between fibre type and toxicity (ANOVA), but a significantly higher toxicity was found for printed versus unprinted cotton and cotton/linen textiles, while the opposite was found for synthetic textiles. Eco-labelled products were evenly distributed on a toxicity scale, which means that eco-labelling in its present form does not necessarily protect users or the environment from exposure to toxic chemicals. Therefore, the results from the present study suggest that bioassays and toxicity tests should become an integrated part of textile environmental quality control programs.

  16. Validation and sensitivity comparisons of micro-scale toxicity tests for the evaluation of freshwater sediment toxicity

    SciTech Connect

    Riebel, P.; Bureau, J.; Blaise, C.; Michaud, J.R.

    1995-12-31

    A three-year study is currently underway to develop a representative and cost-effective battery of toxicity tests for evaluating freshwater sediment and porewater toxicity. Among the tests currently being evaluated are the following: Microtox{trademark} chronic test, Microtox{trademark} solid-phase test, Microtox{trademark} liquid phase test, Thamnotoxkit F{trademark}, Rotoxkit F{trademark}, Daphnia magna IQ test{trademark}, Sediment Toxkit, SOS Chromotest, a Selenastrum capricornutum short exposure assay, and trout hepatocyte assays. Conventional sediment tests with Chironomus tentans, Hyalella azteca and Lumbriculus variegatus, as well as benthic macroinvertebrate community assessments and sediment chemical characterizations are being conducted at two contaminated sites. Toxicity test reproducibility, sensitivity, practicality, cost and ecological relevance are discussed.

  17. Adaptive phenotypic plasticity and local adaptation for temperature tolerance in freshwater zooplankton.

    PubMed

    Yampolsky, Lev Y; Schaer, Tobias M M; Ebert, Dieter

    2014-02-07

    Many organisms have geographical distributions extending from the tropics to near polar regions or can experience up to 30°C temperature variation within the lifespan of an individual. Two forms of evolutionary adaptation to such wide ranges in ambient temperatures are frequently discussed: local adaptation and phenotypic plasticity. The freshwater planktonic crustacean Daphnia magna, whose range extends from South Africa to near arctic sites, shows strong phenotypic and genotypic variation in response to temperature. In this study, we use D. magna clones from 22 populations (one clone per population) ranging from latitude 0° (Kenya) to 66° North (White Sea) to explore the contributions of phenotypic plasticity and local adaptation to high temperature tolerance. Temperature tolerance was studied as knockout time (time until immobilization, T(imm)) at 37°C in clones acclimatized to either 20°C or 28°C. Acclimatization to 28°C strongly increased T(imm), testifying to adaptive phenotypic plasticity. At the same time, Timm significantly correlated with average high temperature at the clones' sites of origin, suggesting local adaptation. As earlier studies have found that haemoglobin expression contributes to temperature tolerance, we also quantified haemoglobin concentration in experimental animals and found that both acclimatization temperature (AccT) and temperature at the site of origin are positively correlated with haemoglobin concentration. Furthermore, Daphnia from warmer climates upregulate haemoglobin much more strongly in response to AccT, suggesting local adaptation for plasticity in haemoglobin expression. Our results show that both local adaptation and phenotypic plasticity contribute to temperature tolerance, and elucidate a possible role of haemoglobin in mediating these effects that differs along a cold-warm gradient.

  18. Dopamine is a key regulator in the signalling pathway underlying predator-induced defences in Daphnia.

    PubMed

    Weiss, Linda C; Leese, Florian; Laforsch, Christian; Tollrian, Ralph

    2015-10-07

    The waterflea Daphnia is a model to investigate the genetic basis of phenotypic plasticity resulting from one differentially expressed genome. Daphnia develops adaptive phenotypes (e.g. morphological defences) thwarting predators, based on chemical predator cue perception. To understand the genomic basis of phenotypic plasticity, the description of the precedent cellular and neuronal mechanisms is fundamental. However, key regulators remain unknown. All neuronal and endocrine stimulants were able to modulate but not induce defences, indicating a pathway of interlinked steps. A candidate able to link neuronal with endocrine responses is the multi-functional amine dopamine. We here tested its involvement in trait formation in Daphnia pulex and Daphnia longicephala using an induction assay composed of predator cues combined with dopaminergic and cholinergic stimulants. The mere application of both stimulants was sufficient to induce morphological defences. We determined dopamine localization in cells found in close association with the defensive trait. These cells serve as centres controlling divergent morphologies. As a mitogen and sclerotization agent, we anticipate that dopamine is involved in proliferation and structural formation of morphological defences. Furthermore, dopamine pathways appear to be interconnected with endocrine pathways, and control juvenile hormone and ecdysone levels. In conclusion, dopamine is suggested as a key regulator of phenotypic plasticity.

  19. Genetic architecture of resistance in Daphnia hosts against two species of host-specific parasites

    PubMed Central

    Routtu, J; Ebert, D

    2015-01-01

    Understanding the genetic architecture of host resistance is key for understanding the evolution of host–parasite interactions. Evolutionary models often assume simple genetics based on few loci and strong epistasis. It is unknown, however, whether these assumptions apply to natural populations. Using a quantitative trait loci (QTL) approach, we explore the genetic architecture of resistance in the crustacean Daphnia magna to two of its natural parasites: the horizontally transmitted bacterium Pasteuria ramosa and the horizontally and vertically transmitted microsporidium Hamiltosporidium tvaerminnensis. These two systems have become models for studies on the evolution of host–parasite interactions. In the QTL panel used here, Daphnia's resistance to P. ramosa is controlled by a single major QTL (which explains 50% of the observed variation). Resistance to H. tvaerminnensis horizontal infections shows a signature of a quantitative trait based in multiple loci with weak epistatic interactions (together explaining 38% variation). Resistance to H. tvaerminnensis vertical infections, however, shows only one QTL (explaining 13.5% variance) that colocalizes with one of the QTLs for horizontal infections. QTLs for resistance to Pasteuria and Hamiltosporidium do not colocalize. We conclude that the genetics of resistance in D. magna are drastically different for these two parasites. Furthermore, we infer that based on these and earlier results, the mechanisms of coevolution differ strongly for the two host–parasite systems. Only the Pasteuria–Daphnia system is expected to follow the negative frequency-dependent selection (Red Queen) model. How coevolution works in the Hamiltosporidium–Daphnia system remains unclear. PMID:25335558

  20. The effect of temperature on the sensitivity of Daphnia magna to cyanobacteria is genus dependent.

    PubMed

    Hochmuth, Jennifer D; De Schamphelaere, Karel A C

    2014-10-01

    In the present study, the authors investigated the effects of 6 different genera of cyanobacteria on multiple endpoints of Daphnia magna in a 21-d life table experiment conducted at 3 different temperatures (15 °C, 19 °C, and 23 °C). The specific aims were to test if the effect of temperature on Daphnia's sensitivity to cyanobacteria differed among different cyanobacteria and if the rank order from most to least harmful cyanobacteria to Daphnia reproduction changed or remained the same across the studied temperature range. Overall, the authors observed a decrease in harmful effects on reproduction with increasing temperature for Microcystis, Nodularia, and Aphanizomenon, and an increase in harmful effects with increasing temperature for Anabaena and Oscillatoria. No effect of temperature was observed on Daphnia sensitivity to Cylindrospermopsis. Harmful effects of Microcystis and Nodularia on reproduction appear to be mirrored by a decrease in length. On the other hand, harmful effects of Anabaena, Aphanizomenon, and Oscillatoria on reproduction were correlated with a decrease in intrinsic rate of natural increase, which was matched by a later onset of reproduction in exposures to Oscillatoria. In addition, the results suggest that the cyanobacteria rank order of harmfulness may change with temperature. Higher temperatures may increase the sensitivity of D. magna to the presence of some cyanobacteria (Anabaena and Oscillatoria) in their diet, whereas the harmful effects of others (Microcystis, Nodularia, and Aphanizomenon) may be reduced by higher temperatures.

  1. Chytrid parasitism facilitates trophic transfer between bloom-forming cyanobacteria and zooplankton (Daphnia)

    NASA Astrophysics Data System (ADS)

    Agha, Ramsy; Saebelfeld, Manja; Manthey, Christin; Rohrlack, Thomas; Wolinska, Justyna

    2016-10-01

    Parasites are rarely included in food web studies, although they can strongly alter trophic interactions. In aquatic ecosystems, poorly grazed cyanobacteria often dominate phytoplankton communities, leading to the decoupling of primary and secondary production. Here, we addressed the interface between predator-prey and host-parasite interactions by conducting a life-table experiment, in which four Daphnia galeata genotypes were maintained on quantitatively comparable diets consisting of healthy cyanobacteria or cyanobacteria infected by a fungal (chytrid) parasite. In four out of five fitness parameters, at least one Daphnia genotype performed better on parasitised cyanobacteria than in the absence of infection. Further treatments consisting of purified chytrid zoospores and heterotrophic bacteria suspensions established the causes of improved fitness. First, Daphnia feed on chytrid zoospores which trophically upgrade cyanobacterial carbon. Second, an increase in heterotrophic bacterial biomass, promoted by cyanobacterial decay, provides an additional food source for Daphnia. In addition, chytrid infection induces fragmentation of cyanobacterial filaments, which could render cyanobacteria more edible. Our results demonstrate that chytrid parasitism can sustain zooplankton under cyanobacterial bloom conditions, and exemplify the potential of parasites to alter interactions between trophic levels.

  2. Atrazine and increased male production by Daphnia: the importance of combining field and laboratory approaches.

    PubMed

    Stoeckel, James A; González, María J; Oris, James T; Kovach, Mathew J; Mace, Kimberly M

    2008-11-01

    Atrazine is one of the most commonly applied herbicides in North America and annually pulses through many midwestern stream and reservoir systems. Previous studies have yielded conflicting results regarding the ability of atrazine to stimulate male production by Daphnia, an effect hypothesized to lower population growth rates during a period of intense larval fish predation. In the present study, populations of Daphnia parvula and Daphnia ambigua exhibited high proportions of males but no ephippial females when atrazine pulsed into Acton Lake, a small midwestern reservoir. Field results thus supported the hypothesis of excess male production by Daphnia during the spring herbicide pulse. In laboratory studies, dose-response studies, and population-level assays revealed no effect of atrazine on male production or population growth rate of multiple clones differing in reproductive strategy and exposure history. However, D. parvula increased male production in response to an endogenous crustacean hormone (methyl farnesoate). Excess male production observed in the field population was therefore not likely caused by atrazine, although we cannot rule out the possibility of interactive effects of atrazine and some other stressor. Apparent signs of endocrine disruption in the presence of high concentrations of a suspected agent should be viewed with caution in the absence of parallel laboratory studies involving individuals from the populations of interest.

  3. Relationship between heat shock protein 70 expression and life span in Daphnia.

    PubMed

    Schumpert, Charles; Handy, Indhira; Dudycha, Jeffry L; Patel, Rekha C

    2014-07-01

    The longevity of an organism is directly related to its ability to effectively cope with cellular stress. Heat shock response (HSR) protects the cells against accumulation of damaged proteins after exposure to elevated temperatures and also in aging cells. To understand the role of Hsp70 in regulating life span of Daphnia, we examined the expression of Hsp70 in two ecotypes that exhibit strikingly different life spans. Daphnia pulicaria, the long lived ecotype, showed a robust Hsp70 induction as compared to the shorter lived Daphnia pulex. Interestingly, the short-lived D. pulex isolates showed no induction of Hsp70 at the mid point in their life span. In contrast to this, the long-lived D. pulicaria continued to induce Hsp70 expression at an equivalent age. We further show that the Hsp70 expression was induced at transcriptional level in response to heat shock. The transcription factor responsible for Hsp70 induction, heat shock factor-1 (HSF-1), although present in aged organisms did not exhibit DNA-binding capability. Thus, the decline of Hsp70 induction in old organisms could be attributed to a decline in HSF-1's DNA-binding activity. These results for the first time, present a molecular analysis of the relationship between HSR and life span in Daphnia.

  4. Inducible Defenses with a "Twist": Daphnia barbata Abandons Bilateral Symmetry in Response to an Ancient Predator.

    PubMed

    Herzog, Quirin; Rabus, Max; Wolfschoon Ribeiro, Bernard; Laforsch, Christian

    2016-01-01

    Predation is one of the most important drivers of natural selection. In consequence a huge variety of anti-predator defenses have evolved in prey species. Under unpredictable and temporally variable predation pressure, the evolution of phenotypically plastic defensive traits is favored. These "inducible defenses", range from changes in behavior, life history, physiology to morphology and can be found in almost all taxa from bacteria to vertebrates. An important group of model organisms in ecological, evolutionary and environmental research, water fleas of the genus Daphnia (Crustacea: Cladocera), are well known for their ability to respond to predators with an enormous variety of inducible morphological defenses. Here we report on the "twist", a body torsion, as a so far unrecognized inducible morphological defense in Daphnia, expressed by Daphnia barbata exposed to the predatory tadpole shrimp Triops cancriformis. This defense is realized by a twisted carapace with the helmet and the tail spine deviating from the body axis into opposing directions, resulting in a complete abolishment of bilateral symmetry. The twisted morphotype should considerably interfere with the feeding apparatus of the predator, contributing to the effectiveness of the array of defensive traits in D. barbata. As such this study does not only describe a completely novel inducible defense in the genus Daphnia but also presents the first report of a free living Bilateria to flexibly respond to predation risk by abandoning bilateral symmetry.

  5. Involvement of Daphnia pulicaria Sir2 in regulating stress response and lifespan.

    PubMed

    Schumpert, Charles A; Anderson, Craig; Dudycha, Jeffry L; Patel, Rekha C

    2016-02-01

    The ability to appropriately respond to proteotoxic stimuli is a major determinant of longevity and involves induction of various heat shock response (HSR) genes, which are essential to cope with cellular and organismal insults throughout lifespan. The activity of NAD+-dependent deacetylase Sir2, originally discovered in yeast, is known to be essential for effective HSR and longevity. Our previous work on HSR inDaphnia pulicaria indicated a drastic reduction of the HSR in older organisms. In this report we investigate the role of Sir2 in regulating HSR during the lifespan of D. pulicaria. We cloned Daphnia Sir2 open reading frame (ORF) to characterize the enzyme activity and confirmed that the overall function of Sir2 was conserved in Daphnia. The Sir2 mRNA levels increased while the enzyme activity declined with age and considering that Sir2 activity regulates HSR, this explains the previously observed age-dependent decline in HSR. Finally, we tested the effect of Sir2 knockdown throughout adult life by using our new RNA interference (RNAi) method by feeding. Sir2 knockdown severely reduced both the median lifespan as well as significantly increased mortality following heat shock. Our study provides the first characterization and functional study of Daphnia Sir2.

  6. Behavioral response of Daphnia magna to silver salt and nanoparticle exposure

    EPA Science Inventory

    Endpoints in the investigation of the toxicity of metallic nanoparticles have varied from genetic and molecular through whole organism responses such as death and reproduction. The work presented here is an effort to quantify behavioral responses of Daphnia magna to exposure to s...

  7. [Lifetime of hydrobionts Daphnia magna in a noncontact-activated water].

    PubMed

    Iksanova, T I; Stekhin, A A; Iakovleva, G V; Kamentskaia, D B

    2015-01-01

    The article is devoted to the study of the influence of non-contact activated water on the lifetime and replicative function of aquatic organisms Daphnia magna, belonging to a highly organized animal organisms. There was established the proportional relationship between the concentration of hydrogen peroxide (in the anion-radical form) and the duration of aquatic lifetime of hydrobionts. In a non contact activated water media with values of redox -potential (Eh)~130mV (against Eh = 213mV--in the control) the lifetime of hydrobionts Daphnia magna is shown to increase in average up to 9 days and reaches 34 days (as 25 days in the control). Replicative junction activated in the aquatic environment does not change, but there was noted a delay in the time of dropping by 7 days in average. Noted regularities in the change in the lifetime of aquatic organisms Daphnia magna in aquatic activated environments are interpreted on the basis of the dependence of the proliferative activity of cells on the concentration of hydrogen peroxide in water. The obtained data on lifetime of Daphnia magna in activated electron-donor environments can serve as proof of the hygienic safety and biological activity of physically-activated (non-contact) drinking water.

  8. Growth of Daphnia magna exposed to mixtures of chemicals with diverse modes of action

    SciTech Connect

    Deneer, J.W.; Seinen, W.; Hermens, J.L.

    1988-02-01

    Concentrations causing inhibition of growth of Daphnia magna after 16 days of exposure were determined for nine chemicals that presumably act through different modes of action. The joint toxic effect of a mixture of these chemicals is found to be nonadditive.

  9. Transcriptomic alterations in Daphnia magna embryos from mothers exposed to hypoxia.

    PubMed

    Lai, Keng-Po; Li, Jing-Woei; Chan, Christine Ying-Shan; Chan, Ting-Fung; Yuen, Karen Wing-Yee; Chiu, Jill Man-Ying

    2016-08-01

    Hypoxia occurs when dissolved oxygen (DO) falls below 2.8mgL(-1) in aquatic environments. It can cause trans-generational effects not only in fish, but also in the water fleas Daphnia. In this study, transcriptome sequencing analysis was employed to identify transcriptomic alterations induced by hypoxia in embryos of Daphnia magna, with an aim to investigate the mechanism underlying the trans-generational effects caused by hypoxia in Daphnia. The embryos (F1) were collected from adults (F0) that were previously exposed to hypoxia (or normoxia) for their whole life. De novo transcriptome assembly identified 18270 transcripts that were matched to the UniProtKB/Swiss-Prot database and resulted in 7419 genes. Comparative transcriptome analysis showed 124 differentially expressed genes, including 70 up- and 54 down-regulated genes under hypoxia. Gene ontology analysis further highlighted three clusters of genes which revealed acclimatory changes of haemoglobin, suppression in vitellogenin gene family and histone modifications. Specifically, the expressions of histone H2B, H3, H4 and histone deacetylase 4 (HDAC4) were deregulated. This study suggested that trans-generational effects of hypoxia on Daphnia may be mediated through epigenetic regulations of histone modifications.

  10. Food availability affects the strength of mutualistic host-microbiota interactions in Daphnia magna.

    PubMed

    Callens, Martijn; Macke, Emilie; Muylaert, Koenraad; Bossier, Peter; Lievens, Bart; Waud, Michael; Decaestecker, Ellen

    2016-04-01

    The symbiotic gut microbial community is generally known to have a strong impact on the fitness of its host. Nevertheless, it is less clear how the impact of symbiotic interactions on the hosts' fitness varies according to environmental circumstances such as changes in the diet. This study aims to get a better understanding of host-microbiota interactions under different levels of food availability. We conducted experiments with the invertebrate, experimental model organism Daphnia magna and compared growth, survival and reproduction of conventionalized symbiotic Daphnia with germ-free individuals given varying quantities of food. Our experiments revealed that the relative importance of the microbiota for the hosts' fitness varied according to dietary conditions. The presence of the microbiota had strong positive effects on Daphnia when food was sufficient or abundant, but had weaker effects under food limitation. Our results indicate that the microbiota can be a potentially important factor in determining host responses to changes in dietary conditions. Characterization of the host-associated microbiota further showed that Aeromonas sp. was the most prevalent taxon in the digestive tract of Daphnia.

  11. Methoprene and 20-OH-ecdysone affect male production in Daphnia pulex.

    PubMed

    Peterson, J K; Kashian, D R; Dodson, S I

    2001-03-01

    Exposure of Daphnia pulex to the insecticide and juvenile hormone-mimic methoprene resulted in a decrease in the incidence of all-male broods and an increase in the incidence of all-female broods compared with controls. These effects were observed at nominal concentrations of 10 and 100 microg/L, within the upper range of concentrations at which methoprene is applied in the environment. Because methoprene has been found to bind to the mammalian retinoid X receptor, we also tested the effects of retinoic acid on Daphnia reproduction. Neither 9-cis-retinoic acid nor all-trans-retinoic acid had any observable effect. Because juvenile hormone and ecdysteroids interact in many insect systems, we also exposed Daphnia to 20-OH-ecdysone. Exposure to the crustacean hormone 20-OH-ecdysone at levels of 1 and 10 microg/L resulted in an increase in all-male broods and a decrease in all-female broods, but 100 microg/L 20-OH-ecdysone resulted in a decrease in all-male broods and an increase in all-female broods. Our results suggest that juvenile hormone and ecdysteroids might play a role in the Daphnia sex determination system.

  12. EFFECTIVE CONCENTRATIONS OF 6 CONTAMINANTS TO LEMMA MINOR, PIMEPHALES PROMELA, DAPHNIA MAGNA, AND CERIODAPHNIA DUBIA

    EPA Science Inventory

    The research presented here resulted in EC50 and LOEC values for the contaminants copper, cadmium, diazinon, atrazine, and cyanide to the species Lemna Minor, Pimephales promelas, Daphnia magna, and Ceriodaphnia dubia. Observed values were used as benchmarks for assessing the se...

  13. Chytrid parasitism facilitates trophic transfer between bloom-forming cyanobacteria and zooplankton (Daphnia)

    PubMed Central

    Agha, Ramsy; Saebelfeld, Manja; Manthey, Christin; Rohrlack, Thomas; Wolinska, Justyna

    2016-01-01

    Parasites are rarely included in food web studies, although they can strongly alter trophic interactions. In aquatic ecosystems, poorly grazed cyanobacteria often dominate phytoplankton communities, leading to the decoupling of primary and secondary production. Here, we addressed the interface between predator-prey and host-parasite interactions by conducting a life-table experiment, in which four Daphnia galeata genotypes were maintained on quantitatively comparable diets consisting of healthy cyanobacteria or cyanobacteria infected by a fungal (chytrid) parasite. In four out of five fitness parameters, at least one Daphnia genotype performed better on parasitised cyanobacteria than in the absence of infection. Further treatments consisting of purified chytrid zoospores and heterotrophic bacteria suspensions established the causes of improved fitness. First, Daphnia feed on chytrid zoospores which trophically upgrade cyanobacterial carbon. Second, an increase in heterotrophic bacterial biomass, promoted by cyanobacterial decay, provides an additional food source for Daphnia. In addition, chytrid infection induces fragmentation of cyanobacterial filaments, which could render cyanobacteria more edible. Our results demonstrate that chytrid parasitism can sustain zooplankton under cyanobacterial bloom conditions, and exemplify the potential of parasites to alter interactions between trophic levels. PMID:27733762

  14. Dopamine is a key regulator in the signalling pathway underlying predator-induced defences in Daphnia

    PubMed Central

    Weiss, Linda C.; Leese, Florian; Laforsch, Christian; Tollrian, Ralph

    2015-01-01

    The waterflea Daphnia is a model to investigate the genetic basis of phenotypic plasticity resulting from one differentially expressed genome. Daphnia develops adaptive phenotypes (e.g. morphological defences) thwarting predators, based on chemical predator cue perception. To understand the genomic basis of phenotypic plasticity, the description of the precedent cellular and neuronal mechanisms is fundamental. However, key regulators remain unknown. All neuronal and endocrine stimulants were able to modulate but not induce defences, indicating a pathway of interlinked steps. A candidate able to link neuronal with endocrine responses is the multi-functional amine dopamine. We here tested its involvement in trait formation in Daphnia pulex and Daphnia longicephala using an induction assay composed of predator cues combined with dopaminergic and cholinergic stimulants. The mere application of both stimulants was sufficient to induce morphological defences. We determined dopamine localization in cells found in close association with the defensive trait. These cells serve as centres controlling divergent morphologies. As a mitogen and sclerotization agent, we anticipate that dopamine is involved in proliferation and structural formation of morphological defences. Furthermore, dopamine pathways appear to be interconnected with endocrine pathways, and control juvenile hormone and ecdysone levels. In conclusion, dopamine is suggested as a key regulator of phenotypic plasticity. PMID:26423840

  15. Differing Daphnia magna assimilation efficiencies for terrestrial, bacterial, and algal carbon and fatty acids.

    PubMed

    Taipale, Sami J; Brett, Michael T; Hahn, Martin W; Martin-Creuzburg, Dominik; Yeung, Sean; Hiltunen, Minna; Strandberg, Ursula; Kankaala, Paula

    2014-02-01

    There is considerable interest in the pathways by which carbon and growth-limiting elemental and biochemical nutrients are supplied to upper trophic levels. Fatty acids and sterols are among the most important molecules transferred across the plant-animal interface of food webs. In lake ecosystems, in addition to phytoplankton, bacteria and terrestrial organic matter are potential trophic resources for zooplankton, especially in those receiving high terrestrial organic matter inputs. We therefore tested carbon, nitrogen, and fatty acid assimilation by the crustacean Daphnia magna when consuming these resources. We fed Daphnia with monospecific diets of high-quality (Cryptomonas marssonii) and intermediate-quality (Chlamydomonas sp. and Scenedesmus gracilis) phytoplankton species, two heterotrophic bacterial strains, and particles from the globally dispersed riparian grass, Phragmites australis, representing terrestrial particulate organic carbon (t-POC). We also fed Daphnia with various mixed diets, and compared Daphnia fatty acid, carbon, and nitrogen assimilation across treatments. Our results suggest that bacteria were nutritionally inadequate diets because they lacked sterols and polyunsaturated omega-3 and omega-6 (omega-3 and omega-6) fatty acids (PUFAs). However, Daphnia were able to effectively use carbon and nitrogen from Actinobacteria, if their basal needs for essential fatty acids and sterols were met by phytoplankton. In contrast to bacteria, t-POC contained sterols and omega-6 and omega-3 fatty acids, but only at 22%, 1.4%, and 0.2% of phytoplankton levels, respectively, which indicated that t-POC food quality was especially restricted with regard to omega-3 PUFAs. Our results also showed higher assimilation of carbon than fatty acids from t-POC and bacteria into Daphnia, based on stable-isotope and fatty acids analysis, respectively. A relatively high (>20%) assimilation of carbon and fatty acids from t-POC was observed only when the proportion of t

  16. Effects of dietary exposure to herbicide and of the nutritive quality of contaminated food on the reproductive output of Daphnia magna.

    PubMed

    Bessa da Silva, M; Abrantes, N; Rocha-Santos, T A P; Duarte, A C; Freitas, A C; Gomes, A M; Carvalho, A P; Marques, J C; Gonçalves, F; Pereira, R

    2016-10-01

    Risk assessment of pesticides has been based on direct toxic effects on aquatic organisms. Indirect effects data are taken into account but with limitations, as it is frequently difficult to predict their real impacts in the ecosystems. In this context the main aim of this work was to assess how the exposure to the herbicide pendimethalin (Prowl(®)), under environmentally relevant concentrations, may compromise the nutritional composition of food for a relevant group of primary consumers of freshwater food webs-the daphnids, thus affecting their reproduction performance and subsequently the long-term sustainability of active populations of this grazer. Therefore, Daphnia magna individuals were chronically exposed in a clean medium to a control diet (NCF - i.e., non-contaminated green algae Raphidocelis subcapitata) and to a contaminated diet (CF - i.e., the same monoalgal culture grown in a medium enriched with pendimethalin in a concentration equivalent to the EC20 for growth inhibition of algae), during which reproductive endpoints were assessed. The algae were analysed for protein, carbohydrate and fatty acid content. The chemical composition of R. subcapitata in the CF revealed a slight decrease on total fatty acid levels, with a particular decrease of essential ω9 monounsaturated fatty acids. In contrast, the protein content was high in the CF. D. magna exposed to CF experienced a 16% reduction in reproduction, measured as the total number of offspring produced per female. Additionally, an internal pendimethalin body burden of 4.226μgg(-1) was accumulated by daphnids fed with CF. Hence, although it is difficult to discriminate the contribution of the pesticide (as a toxic agent transferred through the food web) from that of the food with a poor quality-compromised by the same pesticide, there are no doubts that, under environmentally relevant concentrations of pesticides, both pathways may compromise the populations of freshwater grazers in the long term

  17. Freshwater Biodiversity and Insect Diversification

    PubMed Central

    Dijkstra, Klaas-Douwe B.; Monaghan, Michael T.; Pauls, Steffen U.

    2016-01-01

    Inland waters cover less than one percent of Earth’s surface, but harbor more than six percent of all insect species: nearly 100,000 species from 12 orders spend one or more life stages in freshwater. Little is known about how this remarkable diversity arose, although allopatric speciation and ecological adaptation are thought to be primary mechanisms. Freshwater habitats are exceptionally susceptible to environmental change, and exhibit marked ecological gradients. The amphibiotic lifestyles of aquatic insects result in complex contributions of extinction and allopatric and non-allopatric speciation in species diversification. In contrast to the lack of evolutionary studies, the ecology and habitat preferences of aquatic insects have been intensively studied, in part because of their widespread use as bio-indicators. The combination of phylogenetics with the extensive ecological data provides a promising avenue for future research, making aquatic insects highly suitable models for the study of ecological diversification. PMID:24160433

  18. Water quality for freshwater fish

    SciTech Connect

    Howells, G. )

    1994-01-01

    This timely and up-to-date volume brings together recent critical reviews on water quality requirements for freshwater fish commissioned by the European Inland Fisheries Advisory Commission, an agency of the United Nations Food and Agriculture Organization. It provides a unique and authoritative source of critically evaluated water quality data concerning the effects of chromium, nickel, aluminum and nitrite on freshwater fish and includes an assessment of the toxicity of mixtures. The reports presented in this volume cover all stages of the life cycle and relevant trophic levels, including aquatic invertebrates and plants and potential bioaccumulation through the food chain. An extensive bibliography is provided for each chapter as well as a glossary of terms and a list of fish species mentioned in the text. This compilation of papers is the definitive reference volume for chemists, biologists, ecologists and toxicologists as well as for water resource managers concerned with management and control of pollution in fresh waters.

  19. Liposomes as an alternative delivery system for investigating dietary metal toxicity to Daphnia magna.

    PubMed

    Evens, Roel; De Schamphelaere, Karel A C; Balcaen, Lieve; Wang, Yingying; De Roy, Karen; Resano, Martín; Flórez, María del Rosario; Van der Meeren, Paul; Boon, Nico; Vanhaecke, Frank; Janssen, Colin R

    2011-10-01

    Dietary metal toxicity studies with invertebrates such as Daphnia magna are often performed using metal-contaminated algae as a food source. A drawback of this approach is that it is difficult to distinguish between the direct toxicity of the metal and indirect effects caused by a reduced essential nutrient content in the metal-contaminated diet, due to prior exposure of the algae to the metal. This hampers the study of the mechanisms of dietary metal toxicity in filter-feeding freshwater invertebrates. The aim of the present study was to develop a technique for producing metal-contaminated liposomes as an alternative delivery system of dietary metals. These liposomes are not vulnerable to metal-induced shifts in nutrient quality. Liposomes were prepared by the hydration of phosphatidylcholine in media containing either 0 (control) or 50mg Ni/L. The liposomes had average diameters of 19.31 (control) and 10.48 μm (Ni-laden), i.e., a size appropriate for ingestion by D. magna. The liposome particles were then mixed with uncontaminated green algae in a 1/10 ratio (on a dry wt. basis) to make up two diets that differed in Ni content (i.e., 2.0 μg Ni/g dry wt. in the control and 144.2 μg Ni/g dry wt. in the Ni-contaminated diet, respectively). This diet was then fed to D. magna during a 21-day chronic bioassay. The experiment showed that the Ni content and the size distribution of the liposomes were stable for at least 7 days. Also the use of phosphatidylcholine as a liposome component did not affect the reproduction of the daphnids. Exposure to increased level of dietary Ni resulted in 100% mortality after 14 days of exposure and in an increased whole-body Ni concentration in D. magna of 14.9 and 20.4 μg Ni/g dry wt. after 7 and 14 days of exposure, respectively. The Ni-exposed daphnids also exhibited a reduced size (i.e., 30% smaller than the control) after 7 days and a completely halted growth between day 7 and day 14. In terms of reproduction, the size of the

  20. Sunlight-driven reduction of silver ion to silver nanoparticle by organic matter mitigates the acute toxicity of silver to Daphnia magna.

    PubMed

    Zhang, Zhen; Yang, Xiaoya; Shen, Mohai; Yin, Yongguang; Liu, Jingfu

    2015-09-01

    Due to the unique antibacterial activities, silver nanoparticles (AgNPs) have been extensively used in commercial products. Anthropogenic activities have released considerable AgNPs as well as highly toxic silver ion (Ag(+)) into the aquatic environment. Our recent study revealed that ubiquitous natural organic matter (NOM) could reduce Ag(+) to AgNP under natural sunlight. However, the toxic effect of this process is not well understood. In this work, we prepared mixture solution of Ag(+) and AgNPs with varied Ag(+)% through the sunlight-driven reduction of Ag(+) by NOM and investigated the acute toxicity of the solutions on Daphnia magna. Formation of AgNPs was demonstrated and characterized by comprehensive techniques and the fraction of unconverted Ag(+) was determined by ultrafiltration-inductively coupled plasma mass spectrometry determination. The formation of AgNPs enhanced significantly with the increasing of solution pH and cumulative photosynthetically active radiation of sunlight. The toxicity of the resulting solution was further investigated by using freshwater crustacean D. magna as a model and an 8hr-median lethal concentration (LC50) demonstrated that the reduction of Ag(+) by NOM to AgNPs significantly mitigated the acute toxicity of silver. These results highlight the importance of sunlight and NOM in the fate, transformation and toxicity of Ag(+) and AgNPs, and further indicate that the acute toxicity of AgNPs should be mainly ascribed to the dissolved Ag(+) from AgNPs.

  1. Toxicity of fluoranthene to Daphnia magna, Hyalella azteca, Chironomus tentans, and Stylaria lacustris in water-only and whole sediment exposures

    SciTech Connect

    Suedel, B.C.; Rodgers, J.H. Jr.

    1996-07-01

    Fluoranthene is a polycyclic aromatic hydrocarbon (PAH) with a hydrophobic nature (water solubility = 265 {mu}g/L; U.S. EPA 1980) and a propensity to sorb to sediments. Fluoranthene has a K{sub oc} of 4.65, an intermediate value for PAHs. Fluoranthene can be toxic to some aquatic organisms at concentrations lower than its aqueous solubility. Therefore, desorption from sediments could produce aqueous concentrations that are harmful to aquatic organisms. Very few studies have examined the toxicity of fluoranthene to freshwater organisms. Data for other PAHs show that crustaceans are the most sensitive species, followed by polychaete worms and fish. Effects of fluoranthene-amended sediments on selected marine benthic organisms were examined. The objectives of this research were to (1) determine the relative sensitivities of Daphnia magna Straus, Hyalella azteca Saussure, Chironomus tentans Fabricius, and Stylaria lacustris Linnaeus in 48-hr and 10-d aqueous phase exposures to fluoranthene; and (2) determine the relative responses of these organisms in 10-d fluoranthene-amended sediment exposures. 12 refs., 3 tabs.

  2. Sublethal and Reproductive Effects of Acute and Chronic Exposure to Flowback and Produced Water from Hydraulic Fracturing on the Water Flea Daphnia magna.

    PubMed

    Blewett, Tamzin A; Delompré, Perrine L M; He, Yuhe; Folkerts, Erik J; Flynn, Shannon L; Alessi, Daniel S; Goss, Greg G

    2017-03-07

    Hydraulic fracturing is an industrial process allowing for the extraction of gas or oil. To fracture the rocks, a proprietary mix of chemicals is injected under high pressure, which later returns to the surface as flowback and produced water (FPW). FPW is a complex chemical mixture consisting of trace metals, organic compounds, and often, high levels of salts. FPW toxicity to the model freshwater crustacean Daphnia magna was characterized utilizing acute (48 h median lethal concentrations; LC50) and chronic (21 day) exposures. A decrease in reproduction was observed, with a mean value of 18.5 neonates produced per replicate over a 21 day chronic exposure to 0.04% FPW, which was a significant decrease from the average of 64 neonates produced in the controls. The time to first brood was delayed in the highest FPW (0.04%) treatment. Neonates exhibited an LC50 of 0.19% of full-strength FPW, making them more sensitive than adults, which displayed an LC50 value of 0.75%. Quantitative PCR highlighted significant changes in expression of genes encoding xenobiotic metabolism (cyp4) and moulting (cut). This study is the first to characterize chronic FPW toxicity and will help with the development of environmental monitoring and risk assessment of FPW spills.

  3. Silver Nanowire Exposure Results in Internalization and Toxicity to Daphnia Magna

    PubMed Central

    Scanlan, Leona D.; Reed, Robert B.; Loguinov, Alexandre V.; Antczak, Philipp; Tagmount, Abderrahmane; Aloni, Shaul; Nowinski, Daniel Thomas; Luong, Pauline; Tran, Christine; Karunaratne, Nadeeka; Pham, Don; Lin, Xin Xin; Falciani, Francesco; Higgins, Chris P.; Ranville, James F.; Vulpe, Chris D.; Gilbert, Benjamin

    2013-01-01

    Nanowires (NWs), high-aspect-ratio nanomaterials, are increasingly used in technological materials and consumer products and may have toxicological characteristics distinct from nanoparticles. We carried out a comprehensive evaluation of the physico-chemical stability of four silver nanowires (AgNWs) of two sizes and coatings and their toxicity to Daphnia magna. Inorganic aluminum-doped silica coatings were less effective than organic poly(vinyl pyrrolidone) coatings at preventing silver oxidation or Ag+ release and underwent a significant morphological transformation within one-hour following addition to low ionic strength Daphnia growth media. All AgNWs were highly toxic to D. magna but less toxic than ionic silver. Toxicity varied as a function of AgNW dimension, coating and solution chemistry. Ag+ release in the media could not account for observed AgNW toxicity. Single-particle inductively coupled plasma mass spectrometry (spICPMS) distinguished and quantified dissolved and nanoparticulate silver in microliter-scale volumes of Daphnia magna hemolymph with a limit of detection of approximately 10 ppb. The silver levels within the hemolymph of Daphnia exposed to both Ag+ and AgNW met or exceeded the initial concentration in the growth medium, indicating effective accumulation during filter feeding. Silver-rich particles were the predominant form of silver in hemolymph following exposure to both AgNWs and Ag+. Scanning electron microscopy (SEM) imaging of dried hemolymph found both AgNWs and silver precipitates that were not present in the AgNW stock or the growth medium. Both organic and inorganic coatings on the AgNW were transformed during ingestion or absorption. Pathway, gene ontology and clustering analyses of gene expression response indicated effects of AgNWs distinct from ionic silver on Daphnia magna. PMID:24099093

  4. Enhancement of toxic effects of phenanthrene to Daphnia magna due to the presence of suspended sediment.

    PubMed

    Zhang, Xiaotian; Xia, Xinghui; Dong, Jianwei; Bao, Yimeng; Li, Husheng

    2014-06-01

    In the present work, the influences of suspended sediment (SPS) on the toxic effects of phenanthrene (PHE), one kind of polycyclic aromatic hydrocarbons, to Daphnia magna was studied using a dialysis bag simulation system, which equalized the freely dissolved concentration of PHE between outside the dialysis bag in the presence of SPS and inside the dialysis bag in the absence of SPS. The immobilization and total superoxide dismutase (T-SOD) activity of Daphnia magna caused by PHE (0-0.8 mg L(-1)) were investigated under the influence of different SPS concentrations (0, 1, 3, 5 g L(-1)) during a 96 h-exposure. The results showed that, compared to the absence of SPS, the presence of SPS (1-5 g L(-1)) increased the immobilization of Daphnia magna by 1.6-2.7 times when the freely dissolved concentration of PHE was identical in both systems. The inhibition of T-SOD activity of Daphnia magna by PHE was significantly greater in the presence of SPS than in the absence of SPS (p<0.01). This infers that the PHE sorbed on SPS might be bioavailable and enhanced the toxic effect of PHE to Daphnia magna. The bioavailable fraction of PHE sorbed on SPS ranged from 10.1% to 22.7%, and the contribution of PHE sorbed on SPS to the immobilization caused by total PHE in the exposure system increased with SPS concentration, with the contribution ratio increasing from 36.7% to 57.7% when SPS concentration increased from 1 to 5 g L(-1). This study suggests that only considering the concentrations of hydrophobic organic compounds in the water phase may underestimate their toxicity; and the hydrophobic organic compounds sorbed on SPS should not be ignored in assessment of water quality and the establishment of water quality standard in the future.

  5. Silver nanowire exposure results in internalization and toxicity to Daphnia magna.

    PubMed

    Scanlan, Leona D; Reed, Robert B; Loguinov, Alexandre V; Antczak, Philipp; Tagmount, Abderrahmane; Aloni, Shaul; Nowinski, Daniel Thomas; Luong, Pauline; Tran, Christine; Karunaratne, Nadeeka; Pham, Don; Lin, Xin Xin; Falciani, Francesco; Higgins, Christopher P; Ranville, James F; Vulpe, Chris D; Gilbert, Benjamin

    2013-12-23

    Nanowires (NWs), high-aspect-ratio nanomaterials, are increasingly used in technological materials and consumer products and may have toxicological characteristics distinct from nanoparticles. We carried out a comprehensive evaluation of the physicochemical stability of four silver nanowires (AgNWs) of two sizes and coatings and their toxicity to Daphnia magna . Inorganic aluminum-doped silica coatings were less effective than organic poly(vinyl pyrrolidone) coatings at preventing silver oxidation or Ag(+) release and underwent a significant morphological transformation within 1 h following addition to low ionic strength Daphnia growth media. All AgNWs were highly toxic to D. magna but less toxic than ionic silver. Toxicity varied as a function of AgNW dimension, coating, and solution chemistry. Ag(+) release in the media could not account for observed AgNW toxicity. Single-particle inductively coupled plasma mass spectrometry distinguished and quantified dissolved and nanoparticulate silver in microliter-scale volumes of Daphnia magna hemolymph with a limit of detection of approximately 10 ppb. The silver levels within the hemolymph of Daphnia exposed to both Ag(+) and AgNW met or exceeded the initial concentration in the growth medium, indicating effective accumulation during filter feeding. Silver-rich particles were the predominant form of silver in hemolymph following exposure to both AgNWs and Ag(+). Scanning electron microscopy imaging of dried hemolymph found both AgNWs and silver precipitates that were not present in the AgNW stock or the growth medium. Both organic and inorganic coatings on the AgNW were transformed during ingestion or absorption. Pathway, gene ontology, and clustering analyses of gene expression response indicated effects of AgNWs distinct from ionic silver on Daphnia magna .

  6. Evaluation of the Daphnia magna reproduction test for detecting endocrine disruptors.

    PubMed

    Dang, ZhiChao; Cheng, Yan; Chen, Hui-ming; Cui, Yuan; Yin, Huan-huan; Traas, Theo; Montforts, Mark; Vermeire, Theo

    2012-07-01

    The Daphnia 21 d reproduction test is considered as a comprehensive and decisive test in the OECD Conceptual Framework for testing and assessment of endocrine disrupting chemicals (EDCs). However, how to interpret results of the Daphnia 21 d reproduction test for identification, risk assessment and testing strategy of EDCs remains an unsolved issue. This study analysed a total number of 135 published studies encompassing 86 known EDCs and non-EDCs with different modes of action. Our results show that the majority of effects on apical endpoints (survival, molting, growth, time to reproductive maturity, brood size, the number of broods, and the total number of offspring) do not seem to be EDC-specific. In contrast, the endpoint sex ratio is likely specific to juvenile hormones and their mimics. Variability is quantified for three most reported endpoints survival, the total number of offspring and sex ratio. Quantification of the endpoint sensitivity shows that the sensitivity of the sex ratio is lower than that of the total number of offspring. The Daphnia 21 d reproduction test gives insufficient information to conclude if a substance is an EDC or not. EDCs that are potent in assays in vitro may not be potent in the Daphnia 21 d reproduction test. We conclude that the Daphnia 21 d reproduction test is important for deriving No Observed Effect Concentrations for risk assessment but may produce false negatives in identification of EDCs when used on its own. A targeted testing strategy for selection of species, tests, and endpoints is suggested for identifying EDCs.

  7. Changing Arctic Ocean freshwater pathways.

    PubMed

    Morison, James; Kwok, Ron; Peralta-Ferriz, Cecilia; Alkire, Matt; Rigor, Ignatius; Andersen, Roger; Steele, Mike

    2012-01-04

    Freshening in the Canada basin of the Arctic Ocean began in the 1990s and continued to at least the end of 2008. By then, the Arctic Ocean might have gained four times as much fresh water as comprised the Great Salinity Anomaly of the 1970s, raising the spectre of slowing global ocean circulation. Freshening has been attributed to increased sea ice melting and contributions from runoff, but a leading explanation has been a strengthening of the Beaufort High--a characteristic peak in sea level atmospheric pressure--which tends to accelerate an anticyclonic (clockwise) wind pattern causing convergence of fresh surface water. Limited observations have made this explanation difficult to verify, and observations of increasing freshwater content under a weakened Beaufort High suggest that other factors must be affecting freshwater content. Here we use observations to show that during a time of record reductions in ice extent from 2005 to 2008, the dominant freshwater content changes were an increase in the Canada basin balanced by a decrease in the Eurasian basin. Observations are drawn from satellite data (sea surface height and ocean-bottom pressure) and in situ data. The freshwater changes were due to a cyclonic (anticlockwise) shift in the ocean pathway of Eurasian runoff forced by strengthening of the west-to-east Northern Hemisphere atmospheric circulation characterized by an increased Arctic Oscillation index. Our results confirm that runoff is an important influence on the Arctic Ocean and establish that the spatial and temporal manifestations of the runoff pathways are modulated by the Arctic Oscillation, rather than the strength of the wind-driven Beaufort Gyre circulation.

  8. Sulfur cycling in freshwater sediments

    NASA Technical Reports Server (NTRS)

    Klug, M. J.

    1985-01-01

    Organic sulfur containing compounds represent greater than 80% of the total sulfur in sediments of eutrophic freshwater lakes. Although sedimentary sulfur is predominantly in the form of organic compounds, more sulfur is transformed by sulfate reduction than by any other process. Rates of sulfate reduction in these sediments average 7 mmol/sq m/day. This rate is 19 times greater than the net rate of production of inorganic sulfur from organic compounds on an annual basis.

  9. The dichotomous oxyregulatory behaviour of the planktonic crustacean Daphnia magna.

    PubMed

    Pirow, R; Buchen, I

    2004-02-01

    The dual function of appendage movement (food acquisition, ventilation) proved to be the key to explaining the peculiar oxyregulatory repertoire of the planktonic filter feeder Daphnia magna. Short-term hypoxic exposure experiments with normoxia-acclimated animals under varying food concentrations revealed a dichotomous response pattern with a compensatory tachycardia under food-free conditions and a ventilatory compensation prevailing under food-rich conditions. Food-free, normoxic conditions resulted in maximum appendage beating rates (fA) and half-maximum heart rates (fH), which restricted the scope for oxyregulation to the circulatory system. Food-rich conditions (10(5) algal cells ml(-1)), on the contrary, had a depressing effect on fA whereas fH increased to 83% of the maximum. In this physiological state, D. magna was able to respond to progressive hypoxia with a compensatory increase in ventilation. A conceptual and mathematical model was developed to analyse the efficiency of ventilatory and circulatory adjustments in improving oxygen transport to tissue. Model predictions showed that an increase in perfusion rate was most effective under both food-free and food-rich conditions in reducing the critical ambient oxygen tension (PO2crit) at which oxygen supply to the tissue started to become impeded. By contrast, a hypothetical increase in ventilation rate had almost no effect on PO2crit under food-free conditions, indicating that appendage movement is driven by nutritive rather than respiratory requirements. However, the model predicted a moderate reduction of PO2crit by hyperventilation under food-rich conditions. Since the regulatory scope for an adjustment in fH was found to be limited in D. magna under these conditions, the increase in ventilation rate is the means of choice for a fed animal to cope with short-term, moderate reductions in ambient oxygen availability. Under long-term and more severe hypoxic conditions, however, the increase in the

  10. Phototoxic effects of titanium dioxide nanoparticles on Daphnia magna

    NASA Astrophysics Data System (ADS)

    Mansfield, Charles M.

    Titanium dioxide nanoparticles (TiO2-NP) are one of the most abundantly utilized nanomaterials in the world. Studies have demonstrated the mechanism of acute toxicity in TiO2-NP to be the production of reactive oxygen species (ROS) leading to oxidative stress and mortality in exposed organisms. It has also been demonstrated that the anatase crystalline conformation is capable of catalyzing the cleavage of water molecules to further increase the concentration of ROS in the presence of ultraviolet radiation. This photoenhanced toxicity significantly lowers the toxicity threshold of TiO2-NP to environmentally relevant concentrations (ppb). The goal of this study was to determine whether dietary uptake and accumulation of TiO2-NP in the aquatic filter feeder Daphnia magna resulted in photoenhanced toxicity. D. magna and S. caprincornatum were exposed to aqueous solutions of 20ppm and 200ppm TiO2-NP for 24hrs and then transferred to clean moderately hard water. Samples were taken at various time points, dried, and TiO 2 quantified using ICP-MS. Toxicity assays were run on D. magna using three TiO2-NP (20ppm, 200ppm) exposure protocols and two ultraviolet radiation treatments. The first exposure group was exposed to aqueous solutions of TiO2-NP for the duration of the test. The second exposure group was exposed to TiO2-NP for an hour and then transferred to clean water. The third exposure group was fed S. capricornatum that had been allowed to adsorb TiO2-NP. All samples were then placed in an outdoor UV exposure system and exposed to either full spectrum sunlight (with UV) or filtered sunlight (no UV). Here we show that TiO2 uptake peaked at one hour of exposure likely due to sedimentation of the particles out of suspension, thus decreasing bioavailability for the duration of the test. Interestingly, when D. magna were moved to clean water, aqueous concentrations of TiO2 increase as a result of depuration from the gut tract. Data also suggests these excreted particles

  11. Resolving some practical questions about Daphnia acute toxicity tests

    SciTech Connect

    Barera, Y.; Adams, W.J.

    1981-10-01

    Acute toxicity tests were performed with six age groups of Daphnia magna, ranging from less than or equal to6 h to 216 h, and with five chemicals, selected on the basis of their physical and chemical properties as well as their acute toxicity to D. magna. The age of the daphnids did not significantly alter the 48-h EC/sub 50/ values for the chemicals tested. The maximum difference observed in the 48-h EC/sub 50/ values between the 6-h and 216-h age groups was a factor of 3.9 for linear alkylbenzene sulfonate (LAS). For purposes of standardization, it appears that D. magna up to 48 h of age at the beginning of the test can be used to conduct acute toxicity tests with most chemicals. The results of static acute toxicity tests conducted with butylbenzyl phthalate (BBP) and D. magna in the presence and absence of several commonly used solvents indicate that the acute toxicity of this chemical is not altered by the use of a solvent carrier. The 48-h EC/sub 50/ value for BBP without a solvent was 1.0 mg/L, compared with a range of 1.6 to 2.2 mg/L when acetone, dimethylformamide, ethanol, or triethylene glycol were used as solvent carriers. The acute toxicities of the solvents in the absence of BBP were also determined for D. magna. The values ranged from 9.3 to 52.4 g/L. The results of static acute tests performed with D. magna and BBP in the presence of various concentrations of daphnid foods (algae or trout chow), indicate that the 48-h EC/sub 50/ values increase proportionally with an increase in food concentrations. These results suggest that acute toxicity tests with D. magna should be conducted in the presence of food with chemicals with a high Ksigma if the results are to be used to select the test concentrations for a chronic study with daphnids. The type of food and the concentration used in the acute test should be the same as those used in a chronic test.

  12. Freshwater bacterial lifestyles inferred from comparative genomics.

    PubMed

    Livermore, Joshua A; Emrich, Scott J; Tan, John; Jones, Stuart E

    2014-03-01

    While micro-organisms actively mediate and participate in freshwater ecosystem services, we know little about freshwater microbial genetic diversity. Genome sequences are available for many bacteria from the human microbiome and the ocean (over 800 and 200, respectively), but only two freshwater genomes are currently available: the streamlined genomes of Polynucleobacter necessarius ssp. asymbioticus and the Actinobacterium AcI-B1. Here, we sequenced and analysed draft genomes of eight phylogentically diverse freshwater bacteria exhibiting a range of lifestyle characteristics. Comparative genomics of these bacteria reveals putative freshwater bacterial lifestyles based on differences in predicted growth rate, capability to respond to environmental stimuli and diversity of useable carbon substrates. Our conceptual model based on these genomic characteristics provides a foundation on which further ecophysiological and genomic studies can be built. In addition, these genomes greatly expand the diversity of existing genomic context for future studies on the ecology and genetics of freshwater bacteria.

  13. Acute toxicity of six freshwater mussel species (Glochidia) to six chemicals: Implications for daphnids and Utterbackia imbecillis as surrogates for protection of freshwater mussels (Unionidae)

    USGS Publications Warehouse

    Milam, C.D.; Farris, J.L.; Dwyer, F.J.; Hardesty, D.K.

    2005-01-01

    Acute (24-h) toxicity tests were used in this study to compare lethality responses in early life stages (glochidia) of six freshwater mussel species, Leptodea fragilis, U. imbecillis, Lampsilis cardium, Lampsilis siliquoidea, Megalonaias nervosa, and Ligumia subrostrata, and two standard test organisms, Ceriodaphnia dubia and Daphnia magna. Concentrations of carbaryl, copper, 4-nonylphenol, pentachlorophenol, permethrin, and 2,4-D were used in acute exposures to represent different chemical classes and modes of action. The relative sensitivities of species were evaluated by ranking their LC 50 values for each chemical. We used these ranks to determine the extent to which U. imbecillis (one of the most commonly used unionids in toxicity tests) was representative of the tolerances of other mussels. We also calculated geometric mean LC50s for the families Unionidae and Daphnidae. Rankings of these data were used to assess the extent to which Daphnidae can be used as surrogates for freshwater mussels relative to chemical sensitivity. While no single chemical elicited consistently high or low toxicity estimates, carbaryl and 2,4-D were generally the least toxic to all species tested. No species was always the most sensitive, and Daphnidae were generally protective of Unionidae. Utterbackia imbecillis, while often proposed as a standard unionid mussel test species, did not always qualify as a sufficient surrogate (i.e., a substitute organism that often elicits similar sensitivity responses to the same contaminant exposure) for other species of mussels, since it was usually one of the more tolerant species in our rankings. U. imbecillis should be used as a surrogate species only with this caution on its relative insensitivity. ?? 2005 Springer Science+Business Media, Inc.

  14. Arctic Freshwater Export: Prospects, Impacts, and Challenges

    NASA Astrophysics Data System (ADS)

    Haine, T. W. N.; Stewart, K.

    2012-04-01

    Large freshwater anomalies clearly exist in the Arctic Ocean. They are due to enhanced melting of sea ice, increased runoff, and changes in atmospheric circulation that lead to surface convergence of freshwater. For example, freshwater has accumulated in the Beaufort Sea over the last 30 years, with an extra ≈ 5000 km3-about 25%-being stored. It is likely that this extra freshwater will be released from the Arctic via the Fram Strait and/or the Canadian Archipelago, perhaps as another "Great Salinity Anomaly". The freshwater discharge will likely have impacts on subpolar Atlantic circulation and ecosystems for several years. In light of coupled climate model forecasts, it may herald a new regime for the Arctic/sub-Arctic ocean. An unprecedented opportunity exists to anticipate and observe this discharge process. This contribution will review the state of knowledge about Arctic freshwater anomalies, and outline potential scenarios for future Arctic freshwater export. Key uncertainties in estimating the timing, rates, and pathways of freshwater export will be identified. Challenges for observing systems to monitor the progress of anomalous freshwater will also be discussed.

  15. Davis Pond Freshwater Prediversion Biomonitoring Study: Freshwater Fisheries and Eagles

    USGS Publications Warehouse

    Jenkins, Jill A.; Bourgeois, E. Beth; Jeske, Clint W.

    2008-01-01

    In January 2001, the construction of the Davis Pond freshwater diversion structure was completed by the U.S. Army Corps of Engineers. The diversion of freshwater from the Mississippi River is intended to mitigate saltwater intrusion from the Gulf of Mexico and to lessen the concomitant loss of wetland areas. In addition to the freshwater inflow, Barataria Bay basin would receive nutrients, increased flows of sediments, and water-borne and sediment-bound compounds. The purpose of this biomonitoring study was, therefore, to serve as a baseline for prediversion concentrations of selected contaminants in bald eagle (Haliaeetus leucocephalus) nestlings (hereafter referred to as eaglets), representative freshwater fish, and bivalves. Samples were collected from January through June 2001. Two similarly designed postdiversion studies, as described in the biological monitoring program, are planned. Active bald eagle nests targeted for sampling eaglet blood (n = 6) were generally located southwest and south of the diversion structure. The designated sites for aquatic animal sampling were at Lake Salvador, at Lake Cataouatche, at Bayou Couba, and along the Mississippi River. Aquatic animals representative of eagle prey were collected. Fish were from three different trophic levels and have varying feeding strategies and life histories. These included herbivorous striped mullet (Mugil cephalus), omnivorous blue catfish (Ictalurus furcatus), and carnivorous largemouth bass (Micropterus salmoides). Three individuals per species were collected at each of the four sampling sites. Freshwater Atlantic rangia clams (Rangia cuneata) were collected at the downstream marsh sites, and zebra mussels (Dreissena spp.) were collected on the Mississippi River. The U.S. Geological Survey (USGS) Biomonitoring of Environmental Status and Trends (BEST) protocols served as guides for fish sampling and health assessments. Fish are useful for monitoring aquatic ecosystems because they accumulate

  16. Cloning, expression and localization of DacaCSP2 and DacaCSP3 during different reproductive stages in Daphnia carinata.

    PubMed

    Li, Haixia; Yang, Yang; Xu, Guorong; Wu, Donglei; Lv, Weiwei; Jiang, Qicheng; Zhao, Yunlong

    2016-05-10

    Daphnia carinata are unique freshwater crustaceans that undergo both sexual and asexual reproduction, depending on environmental factors. While the molecular mechanism behind the reproductive transformation has been unknown, chemosensory proteins (CSPs) may be involved. We have cloned the cDNA sequences of two CSP genes from D. carinata using primers based on homologous sequences and rapid amplification of cDNA ends (RACE). The full-length cDNA of DacaCSP2 (GenBank accession no: KM624608) was 632 bp, with an ORF (open reading frame) of 330 bp encoding a 12.02 kDa protein; and the full-length cDNA of DacaCSP3 (GenBank accession no: KM624609) was 935 bp, with an ORF of 342 bp encoding a 12.78kDa protein. Both CSPs encoded an N-terminal signal peptide, four conserved cysteines, an OS-D superfamily domain, a 2Fe-2S ferredoxin domain, an anaphylatoxin domain and an EGF-like domain. DaCaCSP2 and DaCaCSP3 proteins were most closely related to CSPs from Daphnia pulex and were more distantly related to CSPs from other insects. Using quantitative PCR, we found expression levels of DaCaCSP2 and DaCaCSP3 mRNA were highest in sexual females, followed by parthenogenetic females, and lowest in males. The expression levels of DaCaCSP2 and DaCaCSP3 mRNA also increased at lower temperatures, which suggested they could respond to environmental cues. Whole mount in situ hybridization (ISH) showed that DaCaCSP2 and DaCaCSP3 were expressed mainly in the ovaries, summer eggs, thoracic limbs, rectum and second antennae in sexual females; while they were expressed mainly in the ovaries, thoracic limbs, rectum and second antennae in parthenogenetic females. Together, these results suggest that DacaCSP2 and DacaCSP3 may respond to environmental cues and control the reproductive switch from sexual to asexual reproduction in D. carinata.

  17. Toxicity of aqueous C70-gallic acid suspension in Daphnia magna.

    PubMed

    Seda, Brandon C; Ke, Pu-Chun; Mount, Andrew S; Klaine, Stephen J

    2012-01-01

    The present study assessed the toxic effects of stable aqueous colloidal suspensions of gallic-acid-stabilized C(70) fullerene on Daphnia magna. The suspensions were stabilized through noncovalent surface modification with gallic acid. In addition to whole-organism responses, changes in antioxidative processes in D. magna were quantified. Acute toxicity was observed with 96LC50 for C(70) -gallic acid of 0.4 ± 0.1 mg/L C(70) . Daphnia magna fecundity was significantly reduced in 21-d bioassays at C(70) -gallic aqcid concentrations below quantifiable limits. Antioxidant enzyme activities of glutathione peroxidase and superoxide dismutase as well as lipid peroxidation suggested that exposed organisms experienced oxidative stress. Microscopic techniques used to determine cellular toxicity via apoptosis proved unsuccessful.

  18. Rapid toxicity screening tests for aquatic biota. 1. Methodology and experiments with Daphnia magna

    SciTech Connect

    Janssen, C.R.; Persoone, G. )

    1993-04-01

    A promising new and rapid toxicity screening test was developed, the concept and principles of which are presented. The method consists of visual observation of in vivo inhibition of an enzymatic process, using a fluorescent substrate. Juvenile Daphnia magna was exposed to a toxicant dilution series for 1 h, after which the substrate was added and the enzymatic inhibition was observed visually, using a long-wave UV light. The 1-h EC50 results of 11 pure compounds are presented and compared to the conventional 24- and 48-h Daphnia magna EC50s. All 1-h fluorescence EC50s were of the same order of magnitude and correlated very well with the 24- and 48-h EC50s. The sensitivity and reproducibility of this cost-effective screening test were compared to those of the Microtox[reg sign] test. The scope for application and the potential of this new rapid toxicity screening test are evaluated.

  19. Accumulation of dieldrin in an alga (Scenedesmus obliquus), Daphnia magna, and the guppy (Poecilia reticulata)

    USGS Publications Warehouse

    Reinert, Robert E.

    1972-01-01

    Scenedesmus obliquus, Daphnia magna, and Poecilia reticulata accumulated dieldrin directly from water; average concentration factors (concentration in organism, dry weight, divided by concentration in water) were 1282 for the alga, 13,954 for D. magna, and 49,307 (estimated) for the guppy. The amount accumulated by each species at equilibrium (after about 1.5, 3-4, and 18 days, respectively) was directly proportional to the concentration of dieldrin in the water. Daphnia magna and guppies accumulated more dieldrin from water than from food that had been exposed to similar concentrations in water. When guppies were fed equal daily rations of D. magna containing different concentrations of insecticide, the amounts of dieldrin accumulated by the fish were directly proportional to the concentration in D. magna; when two lots of guppies were fed different quantities of D. magna (10 and 20 organisms per day) containing identical concentrations of dieldrin, however, the amounts accumulated did not differ substantially.

  20. Effect of age on sensitivity of daphnia magna to cadmium, copper and cyanazine

    SciTech Connect

    Nebeker, A.V.; Cairns, M.A.; Onjukka, S.T.; Titus, R.H.

    1986-01-01

    Daphnia magna were exposed to cadmium, copper, and cyanazine to determine the relative sensitivities of several age groups: less than 4 h, less than 24 h, 1 d, 2 d, 3 d, 4 d, 5 d, and 6 d old. Mean cadmium 48-h EC50 values for each age group ranged from 23 to 164 micrograms/L. Mean copper EC50 values ranged from 6 to 18 micrograms/L. Cyanazine EC50 values ranged from 53 to 106 micrograms/L. The 1-d-old Daphnia mean EC50s were 48 and 49 micrograms/L for cadmium, 10 and 10 micrograms/L for copper and 84 and 86 microgram/L for cyanazine, respectively. These similar sensitivities indicate that older animals can be used in tests equally as well as younger animals, thus simplifying the recovery of daphnids in acute sediment toxicity tests.

  1. Freshwater Biological Traits Database (Final Report)

    EPA Science Inventory

    Cover of the <span class=Freshwater Biological Traits Database Final Report"> This final report discusses the development of a database of freshwater biolo...

  2. Freshwater Ecology. LC Science Tracer Bullet.

    ERIC Educational Resources Information Center

    Niskern, Diana, Comp.

    Freshwater ecosystems include lakes, ponds, streams, rivers, and certain types of wetlands. This literature and resources guide is not intended to be a comprehensive bibliography on freshwater ecology; the guide is designed--as the name of the series implies--to put the reader or student "on target." Other literature guides related to…

  3. Freshwater Biological Traits Database (Final Report)

    EPA Science Inventory

    EPA announced the release of the final report, Freshwater Biological Traits Database. This report discusses the development of a database of freshwater biological traits. The database combines several existing traits databases into an online format. The database is also...

  4. Effects of Pollution on Freshwater Fish.

    ERIC Educational Resources Information Center

    Brungs, W. A.; And Others

    1978-01-01

    Presents a literature review of the effects of pollution on freshwater fish, covering publications of 1976-77. This review includes: (1) water quality; (2) pesticide pollutants; (3) chemical pollutants; (4) miscellaneous pollutants; and (5) physical factors of pollution on freshwater fish. A list of 338 references is also presented. (HM)

  5. Why are freshwater fish so threatened?

    USGS Publications Warehouse

    Closs, Gerard P.; Angermeier, Paul; Darwall, William R.T.; Balcombe, Stephen R.

    2015-01-01

    Understanding why so many freshwater fish species are threatened requires some understanding of their biology, diversity, distribution, biogeography and ecology, but also some appreciation of the social, economic and political forces that are causing humans to destroy the natural ecosystems upon which we all ultimately depend. To begin to understand the diversity of freshwater fishes, we first need to consider the processes that generated and continue to sustain the diversity of species we see today. Based on an understanding of how freshwater fish diversity is generated and sustained, we consider how vulnerable or resilient various freshwater fishes are to the range of anthropogenic impacts that impinge on freshwater ecosystems. Finally, we discuss how social, political and economic drivers influence human impacts on natural systems, and the changes needed to current models of development that can lead to a sustainable future for humans and the diverse range of freshwater fish species with which we share our planet. The aim of this chapter is to provide an overview of the key issues and threats driving the declines in freshwater fish diversity identified in Chapter 1; subsequent chapters provide more detail on the key issues and address our options for developing a sustainable future for freshwater fishes.

  6. Response of Daphnia's antioxidant system to spatial heterogeneity in Cyanobacteria concentrations in a lowland reservoir.

    PubMed

    Wojtal-Frankiewicz, Adrianna; Bernasińska, Joanna; Frankiewicz, Piotr; Gwoździński, Krzysztof; Jurczak, Tomasz

    2014-01-01

    Many species and clones of Daphnia inhabit ecosystems with permanent algal blooms, and they can develop tolerance to cyanobacterial toxins. In the current study, we examined the spatial differences in the response of Daphnia longispina to the toxic Microcystis aeruginosa in a lowland eutrophic dam reservoir between June (before blooms) and September (during blooms). The reservoir showed a distinct spatial pattern in cyanobacteria abundance resulting from the wind direction: the station closest to the dam was characterised by persistently high Microcystis biomass, whereas the upstream stations had a significantly lower biomass of Microcystis. Microcystin concentrations were closely correlated with the cyanobacteria abundance (r = 0.93). The density of daphniids did not differ among the stations. The main objective of this study was to investigate how the distribution of toxic Microcystis blooms affects the antioxidant system of Daphnia. We examined catalase (CAT) activity, the level of the low molecular weight antioxidant glutathione (GSH), glutathione S-transferase (GST) activity and oxidative stress parameters, such as lipid peroxidation (LPO). We found that the higher the abundance (and toxicity) of the cyanobacteria, the lower the values of the antioxidant parameters. The CAT activity and LPO level were always significantly lower at the station with the highest M. aeruginosa biomass, which indicated the low oxidative stress of D. longispina at the site with the potentially high toxic thread. However, the low concentration of GSH and the highest activity of GST indicated the occurrence of detoxification processes at this site. These results demonstrate that daphniids that have coexisted with a high biomass of toxic cyanobacteria have effective mechanisms that protect them against the toxic effects of microcystins. We also conclude that Daphnia's resistance capacity to Microcystis toxins may differ within an ecosystem, depending on the bloom's spatial

  7. Response of Daphnia's Antioxidant System to Spatial Heterogeneity in Cyanobacteria Concentrations in a Lowland Reservoir

    PubMed Central

    Wojtal-Frankiewicz, Adrianna; Bernasińska, Joanna; Frankiewicz, Piotr; Gwoździński, Krzysztof; Jurczak, Tomasz

    2014-01-01

    Many species and clones of Daphnia inhabit ecosystems with permanent algal blooms, and they can develop tolerance to cyanobacterial toxins. In the current study, we examined the spatial differences in the response of Daphnia longispina to the toxic Microcystis aeruginosa in a lowland eutrophic dam reservoir between June (before blooms) and September (during blooms). The reservoir showed a distinct spatial pattern in cyanobacteria abundance resulting from the wind direction: the station closest to the dam was characterised by persistently high Microcystis biomass, whereas the upstream stations had a significantly lower biomass of Microcystis. Microcystin concentrations were closely correlated with the cyanobacteria abundance (r = 0.93). The density of daphniids did not differ among the stations. The main objective of this study was to investigate how the distribution of toxic Microcystis blooms affects the antioxidant system of Daphnia. We examined catalase (CAT) activity, the level of the low molecular weight antioxidant glutathione (GSH), glutathione S-transferase (GST) activity and oxidative stress parameters, such as lipid peroxidation (LPO). We found that the higher the abundance (and toxicity) of the cyanobacteria, the lower the values of the antioxidant parameters. The CAT activity and LPO level were always significantly lower at the station with the highest M. aeruginosa biomass, which indicated the low oxidative stress of D. longispina at the site with the potentially high toxic thread. However, the low concentration of GSH and the highest activity of GST indicated the occurrence of detoxification processes at this site. These results demonstrate that daphniids that have coexisted with a high biomass of toxic cyanobacteria have effective mechanisms that protect them against the toxic effects of microcystins. We also conclude that Daphnia's resistance capacity to Microcystis toxins may differ within an ecosystem, depending on the bloom's spatial

  8. Bioaccumulation of perfluoroalkyl substances by Daphnia magna in water with different types and concentrations of protein.

    PubMed

    Xia, Xinghui; Rabearisoa, Andry H; Jiang, Xiaoman; Dai, Zhineng

    2013-10-01

    Perfluoroalkyl substances (PFASs) are sometimes regarded as proteinophilic compounds, however, there is no research report about the effect of environmental protein on the bioaccumulation of PFASs in waters. In the present study we investigated influences of protein on the bioaccumulation of six kinds of PFASs by Daphnia magna in water; it included perfluorooctane sulfonate, perfluorooctanoic acid, perfluorononanoic acid, perfluorodecanoic acid, perfluoroundecanoic acid, and perfluorododecanoic acid. Two types of protein including bovine albumin from animal and soy peptone from plant were compared and the effects of protein concentration were investigated. Both types of protein at high concentrations (10 and 20 mg L(-1)) suppressed the bioaccumulation of PFASs. When protein concentration increased from 0 to 20 mg L(-1), the decreasing ratios of the PFAS body burden (35.3-52.9%) in Daphnia magna induced by bovine albumin were significantly higher than those (22.0-36.6%) by soy peptone. The dialysis bag experiment results showed that the binding of PFASs to protein followed the Freundlich isotherm, suggesting it is not a linear partitioning process but an adsorption-like process. The partition coefficients of PFASs between bovine albumin and water were higher compared to soy peptone; this resulted in higher reducing rates of freely dissolved concentrations of PFASs with increasing bovine albumin concentration, leading to a stronger suppression of PFAS bioaccumulation. However, the presence of both types of protein with a low concentration (1 mg L(-1)) enhanced the bioaccumulation of PFASs. Furthermore, the water-based bioaccumulation factor based on the freely dissolved concentrations of PFASs even increased with and the depuration rate constants of PFASs from Daphnia magna decreased with protein concentration, suggesting that protein would not only reduce the bioavailable concentrations and uptake rates of PFASs but also lower the elimination rates of PFASs in

  9. Effects of crepuscular photoenvironment on light-induced behavior of Daphnia.

    PubMed

    Grover, P B; Miller, R J

    1984-11-01

    Phototactic response rates in the aquatic crustacean Daphnia magna were found to increase greatly when cultured under a lighting regime that included simulation of sunset and sunrise. The changes in intensity and color of the crepuscular periods are known to be the primary stimulus for vertical migrations of many planktonic forms, and may have importance to many other animals as well. The value of this type of lighting to investigators of animal behavior and physiology is discussed.

  10. Variation in copper effects on kairomone-mediated responses in Daphnia pulicaria.

    PubMed

    DeMille, C M; Arnott, S E; Pyle, G G

    2016-04-01

    Chemical signals play an integral role in many predator-prey relationships but their effectiveness can be altered by environmental conditions. Prey species can detect predator kairomones, which induce anti-predator defenses. An example of this predator-prey relationship exists between Daphnia spp. and Chaoborus spp.; however, when living in water contaminated with low concentrations of copper (Cu) Daphnia can fail to respond to Chaoborus kairomone and, in turn, become more susceptible to predation. This has implications for Daphnia living in regions with Cu contamination, such as areas where mining activity has resulted in increased levels of metals in the surrounding lakes. We examined kairomone-mediated responses of multiple Daphnia pulicaria clones obtained from 8 lakes in Ontario, Canada, in the absence and presence of environmentally-relevant Cu concentrations. Life history traits and morphological anti-predator defenses were assessed using neonates collected from mothers that were exposed to kairomone and Cu treatments. We found that kairomone-mediated responses and Cu-tolerance varied among D. pulicaria clones. Clones exposed to kairomone, in the absence of Cu additions, had diverse responses, including larger neonates, delayed reproduction, or altered brood size relative to no-kairomone controls. These kairomone-induced responses act as antipredator defense strategies against Chaoborus by preventing predation or stabilizing population growth. When exposed to Cu, two clones were able to respond to kairomone, while four clones no longer induced a response to kairomone. This variation in non-lethal effects of Cu on aquatic organisms suggests that toxicity tests should incorporate multiple genotypes and include predator-prey interactions.

  11. Effects of sublethal concentrations of selenium on metabolism and filtering rate of Daphnia pulex

    SciTech Connect

    Reading, J.T.; Buikema, A.L. Jr.

    1980-06-01

    The purpose of this research was to evaluate the sublethal effects of selenium on Daphnia pulex oxygen consumption and filtering rate. Selenium is a trace element which is receiving increased attention as an environmental pollutant because of its high concentration in coal and other fossil fuels. It is the least plentiful and most toxic of the essential trace elements with a very narrow margin of safety between required and toxic doses.

  12. Single nucleotide polymorphism discovery from expressed sequence tags in the waterflea Daphnia magna

    PubMed Central

    2011-01-01

    Background Daphnia (Crustacea: Cladocera) plays a central role in standing aquatic ecosystems, has a well known ecology and is widely used in population studies and environmental risk assessments. Daphnia magna is, especially in Europe, intensively used to study stress responses of natural populations to pollutants, climate change, and antagonistic interactions with predators and parasites, which have all been demonstrated to induce micro-evolutionary and adaptive responses. Although its ecology and evolutionary biology is intensively studied, little is known on the functional genomics underpinning of phenotypic responses to environmental stressors. The aim of the present study was to find genes expressed in presence of environmental stressors, and target such genes for single nucleotide polymorphic (SNP) marker development. Results We developed three expressed sequence tag (EST) libraries using clonal lineages of D. magna exposed to ecological stressors, namely fish predation, parasite infection and pesticide exposure. We used these newly developed ESTs and other Daphnia ESTs retrieved from NCBI GeneBank to mine for SNP markers targeting synonymous as well as non synonymous genetic variation. We validate the developed SNPs in six natural populations of D. magna distributed at regional scale. Conclusions A large proportion (47%) of the produced ESTs are Daphnia lineage specific genes, which are potentially involved in responses to environmental stress rather than to general cellular functions and metabolic activities, or reflect the arthropod's aquatic lifestyle. The characterization of genes expressed under stress and the validation of their SNPs for population genetic study is important for identifying ecologically responsive genes in D. magna. PMID:21668940

  13. Evaluation of the ultrasonic method for solubilizing Daphnia magna before liquid scintillation counting

    SciTech Connect

    Dauble, D.D.; Hanf, R.W. Jr.; Carlile, D.W.

    1984-11-01

    Adult Daphnia magna were exposed to /sup 14/C-labeled phenol and tissues analyzed for /sup 14/C uptake by three methods: (1) tissue solubilizer, (2) tissue solubilizer plus sonication, and (3) sonication alone. Analysis by liquid scintillation counting revealed that measurements of total activity among treatments were not significantly different (..cap alpha.. less than or equal to 0.10) at two count levels. Sonicated samples showed less variation than tissue samples that were solubilized. 5 references, 1 table.

  14. Toxicity to Daphnia pulex and QSAR predictions for polycyclic hydrocarbons representative of Great Lakes contaminants

    USGS Publications Warehouse

    Passino-Reader, D.R.; Hickey, J.P.; Ogilvie, L.M.

    1997-01-01

    The objectives of this study were (1) to determine the toxicity of several types of polycyclic hydrocarbons characteristic of Great Lakes samples to Daphnia pulex, a Great Lakes zooplankter, (2) to investigate the influence of different structural characteristics on toxicity, and (3) to determine the linear solvation energy relationship (LSER) parameters and model that describe these compounds. These results will be related to comparative toxicity of other Great Lakes environmental compounds and to their application in site specific risk assessment.

  15. Freshwater to seawater transitions in migratory fishes

    USGS Publications Warehouse

    Zydlewski, Joseph; Michael P. Wilkie,

    2012-01-01

    The transition from freshwater to seawater is integral to the life history of many fishes. Diverse migratory fishes express anadromous, catadromous, and amphidromous life histories, while others make incomplete transits between freshwater and seawater. The physiological mechanisms of osmoregulation are widely conserved among phylogenetically diverse species. Diadromous fishes moving between freshwater and seawater develop osmoregulatory mechanisms for different environmental salinities. Freshwater to seawater transition involves hormonally mediated changes in gill ionocytes and the transport proteins associated with hypoosmoregulation, increased seawater ingestion and water absorption in the intestine, and reduced urinary water losses. Fishes attain salinity tolerance through early development, gradual acclimation, or environmentally or developmentally cued adaptations. This chapter describes adaptations in diverse taxa and the effects of salinity on growth. Identifying common strategies in diadromous fishes moving between freshwater and seawater will reveal the ecological and physiological basis for maintaining homeostasis in different salinities, and inform efforts to conserve and manage migratory euryhaline fishes.

  16. Freshwater for resilience: a shift in thinking.

    PubMed Central

    Folke, Carl

    2003-01-01

    Humanity shapes freshwater flows and biosphere dynamics from a local to a global scale. Successful management of target resources in the short term tends to alienate the social and economic development process from its ultimate dependence on the life-supporting environment. Freshwater becomes transformed into a resource for optimal management in development, neglecting the multiple functions of freshwater in dynamic landscapes and its fundamental role as the bloodstream of the biosphere. The current tension of these differences in worldview is exemplified through the recent development of modern aquaculture contrasted with examples of catchment-based stewardship of freshwater flows in dynamic landscapes. In particular, the social and institutional dimension of catchment management is highlighted and features of social-ecological systems for resilience building are presented. It is concluded that this broader view of freshwater provides the foundation for hydrosolidarity. PMID:14728796

  17. Discrimination of ion toxicity in six produced waters using the freshwater salinity toxicity relationships and TIE procedures

    SciTech Connect

    Tietge, J.E.; Hockett, J.R.; Evans, J.M.

    1995-12-01

    Research to characterize the toxicity of common ions to freshwater organisms resulted in the development of predictive toxicity models (FW STR) for three freshwater species (Ceriodaphnia dubia, Pimephales promelas, and Daphnia magna). The FW STR models, derived from acute toxicity data, focused on the toxicity of seven common ions. These predictive models were used in conjuntion with Phase I TIE procedures to evaluate the contribution of common ion toxicity in six produced water samples ranging in total salinity from 1.7 to 58.1 g/L. Initial toxicities of all six samples were compared to the model predictions. Four produced water samples were found to have toxicity due to common ion concentrations only. Two samples were found to exhibit more toxicity than expected from ion concentrations alone. These samples were subjected to Phase I TIE procedures. Toxicities were reduced by specific Phase I TIE manipulations to those predicted by the FW STR models. Mock effluents were used to verify the results. The combination of the FW STR models with Phase I TIE procedures successfully quantified the toxicity due to common ions.

  18. Major ion toxicity of six produced waters to three freshwater species: Application of ion toxicity models and TIE procedures

    SciTech Connect

    Tietge, J.E.; Hockett, J.R.; Evans, J.M.

    1997-10-01

    Previous research to characterize the acute toxicity of major ions to freshwater organisms resulted in the development of statistical toxicity models for three freshwater species (Ceriodaphnia dubia, Pimephales promelas, and Daphnia magna). These ion toxicity models estimate the toxicity of seven major ions utilizing logistic regression. In this study, the ion toxicity models were used in conjunction with Phase 1 toxicity identification evaluation (TIE) procedures to evaluate the contribution of major ion toxicity to the total toxicity of six produced water samples ranging in total salinity from 1.7 to 58.1 g/L. Initial toxicities of all six samples were compared to the model predictions. Four produced waters were found to have toxicity consistent with toxicity attributable to major ion concentrations only. Two produced waters were found to exhibit more toxicity than expected from ion concentrations alone. These samples were subjected to Phase 1 TIE procedures. Toxicities were reduced by specific Phase 1 TIE manipulations to those predicted by the ion toxicity models. Mock effluents were used to verify the results. The combination of the ion toxicity models with Phase 1 TIE procedures successfully quantified the toxicity due to major ions in six produced water samples.

  19. Biotransformation pathways of biocides and pharmaceuticals in freshwater crustaceans based on structure elucidation of metabolites using high resolution mass spectrometry.

    PubMed

    Jeon, Junho; Kurth, Denise; Hollender, Juliane

    2013-03-18

    So far, there is limited information on biotransformation mechanisms and products of polar contaminants in freshwater crustaceans. In the present study, metabolites of biocides and pharmaceuticals formed in Gammarus pulex and Daphnia magna were identified using liquid chromatography-high resolution mass spectrometry. Different confidence levels were assigned to the identification of metabolites without reference standards using a framework based on the background evidence used for structure elucidation. Twenty-five metabolites were tentatively identified for irgarol, terbutryn, tramadol, and venlafaxine in G. pulex (21 via oxidation and 4 via conjugation reactions) and 11 metabolites in D. magna (7 via oxidation and 4 via conjugation reactions), while no evidence of metabolites for clarithromycin and valsartan was found. Of the 360 metabolites predicted for the four parent compounds using pathway prediction systems and expert knowledge, 23 products were true positives, while 2 identified metabolites were unexpected products. Observed oxidative reactions included N- and O-demethylation, hydroxylation, and N-oxidation. Glutathione conjugation of selected biocides followed by subsequent reactions forming cysteine conjugates was described for the first time in freshwater invertebrates.

  20. Mating behavior of Daphnia: impacts of predation risk, food quantity, and reproductive phase of females.

    PubMed

    La, Geung-Hwan; Choi, Jong-Yun; Chang, Kwang-Hyeon; Jang, Min-Ho; Joo, Gea-Jae; Kim, Hyun-Woo

    2014-01-01

    High predation risk and food depletion lead to sexual reproduction in cyclically parthenogenetic Daphnia. Mating, the core of sexual reproduction, also occurs under these conditions. Assessment of the environmental conditions and alteration of mating efforts may aid in determining the success of sexual reproduction. Here, we evaluated the impacts of predation risk, food quantity, and reproductive phase of females on the mating behavior of Daphnia obtusa males including contact frequency and duration using video analysis. Mating-related behavior involved male-female contact (mating) as well as male-male contact (fighting). Mating frequency increased while unnecessary fighting decreased in the presence of predation risk. In addition, low food concentration reduced fighting between males. Males attempted to attach to sexual females more than asexual females, and fighting occurred more frequently in the presence of sexual females. Duration of mating was relatively long; however, males separated shortly after contact in terms of fighting behavior. Thus, assessment of environmental factors and primary sexing of mates were performed before actual contact, possibly mechanically, and precise sex discrimination was conducted after contact. These results suggest that mating in Daphnia is not a random process but rather a balance between predation risk and energetic cost that results in changes in mating and fighting strategies.

  1. Sequential assessment via daphnia and zebrafish for systematic toxicity screening of heterogeneous substances.

    PubMed

    Jang, Gun Hyuk; Park, Chang-Beom; Kang, Benedict J; Kim, Young Jun; Lee, Kwan Hyi

    2016-09-01

    Environment and organisms are persistently exposed by a mixture of various substances. However, the current evaluation method is mostly based on an individual substance's toxicity. A systematic toxicity evaluation of heterogeneous substances needs to be established. To demonstrate toxicity assessment of mixture, we chose a group of three typical ingredients in cosmetic sunscreen products that frequently enters ecosystems: benzophenone-3 (BP-3), ethylhexyl methoxycinnamate (EHMC), and titanium dioxide nanoparticle (TiO2 NP). We first determined a range of nominal toxic concentration of each ingredient or substance using Daphnia magna, and then for the subsequent organismal level phenotypic assessment, chose the wild-type zebrafish embryos. Any phenotype change, such as body deformation, led to further examinations on the specific organs of transgenic zebrafish embryos. Based on the systematic toxicity assessments of the heterogeneous substances, we offer a sequential environmental toxicity assessment protocol that starts off by utilizing Daphnia magna to determine a nominal concentration range of each substance and finishes by utilizing the zebrafish embryos to detect defects on the embryos caused by the heterogeneous substances. The protocol showed additive toxic effects of the mixtures. We propose a sequential environmental toxicity assessment protocol for the systematic toxicity screening of heterogeneous substances from Daphnia magna to zebrafish embryo in-vivo models.

  2. Molecular characterization of the gene checkpoint homolog 1 in Daphnia carinata during different reproductive phases.

    PubMed

    Kong, L; Li, H X; Wu, D L; Xu, G R; Wang, D L; Zhao, Y L

    2016-04-04

    Full-length cDNA of the gene checkpoint homolog 1 (Chk1) was cloned from Daphnia carinata and designated DcarChk1. DcarChk1 cDNA was 1817 bp in length and encoded a 497-amino acid polypeptide. Phylogenetic analyses revealed that DcarChk1 was most closely related to Chk1 of Daphnia pulex, followed by homologous genes of insects. Expression of DcarChk1 was higher in adult Daphnia than in larvae, and significantly higher in males than females, as determined by real-time polymerase chain reaction analysis. Using whole-mount in situ hybridization techniques, DcarChk1 in parthenogenetic females was found to be expressed mainly on the head surface, capillus, and carapace valve edge. In contrast, in sexual females, DcarChk1 was expressed mainly in the joint of the second antenna, and in the thoracic limbs and capillus. These results suggest that DcarChk1 plays a significant role in both the growth and development, as well as in regulating reproductive plasticity, in D. carinata.

  3. Resources, key traits and the size of fungal epidemics in Daphnia populations.

    PubMed

    Civitello, David J; Penczykowski, Rachel M; Smith, Aimee N; Shocket, Marta S; Duffy, Meghan A; Hall, Spencer R

    2015-07-01

    Parasites can profoundly affect host populations and ecological communities. Thus, it remains critical to identify mechanisms that drive variation in epidemics. Resource availability can drive epidemics via traits of hosts and parasites that govern disease spread. Here, we map resource-trait-epidemic connections to explain variation in fungal outbreaks (Metschnikowia bicuspidata) in a zooplankton host (Daphnia dentifera) among lakes. We predicted epidemics would grow larger in lakes with more phytoplankton via three energetic mechanisms. First, resources should stimulate Daphnia reproduction, potentially elevating host density. Secondly, resources should boost body size of hosts, enhancing exposure to environmentally distributed propagules through size-dependent feeding. Thirdly, resources should fuel parasite reproduction within hosts. To test these predictions, we sampled 12 natural epidemics and tracked edible algae, fungal infection prevalence, body size, fecundity and density of hosts, as well as within-host parasite loads. Epidemics grew larger in lakes with more algal resources. Structural equation modelling revealed that resource availability stimulated all three traits (host fecundity, host size and parasite load). However, only parasite load connected resources to epidemic size. Epidemics grew larger in more dense Daphnia populations, but host density was unrelated to host fecundity (thus breaking its link to resources). Thus, via energetic mechanisms, resource availability can stimulate key trait(s) governing epidemics in nature. A synthetic focus on resources and resource-trait links could yield powerful insights into epidemics.

  4. The coexistence of hybrid and parental Daphnia: the role of parasites

    PubMed Central

    Wolinska, Justyna; Bittner, Kerstin; Ebert, Dieter; Spaak, Piet

    2006-01-01

    Parasite driven time-lagged negative frequency-dependent selection of hosts has been studied in natural populations by following changes in host genotype frequencies over time. However, such dynamics have not been considered at higher taxonomic levels, for example, between parental species and their hybrids. In a field study on a Daphnia hybrid system, we observed that one Daphnia taxon first was relatively under-infected, but became over-infected after a strong increase in frequency. This finding is consistent with the idea of parasite evolution towards the most frequent host taxon. In two experiments, we investigated whether the assumptions made by a model of negative frequency-dependent selection apply to our host taxa system. First, we showed that the parasite can change the outcome of taxa competition and secondly, we confirmed that the over-infection of one host taxon observed in the field has a genetic basis. Our results indicate that the incorporation of host–parasite interactions at the species level may allow us to gain a more complete picture of forces driving dynamic taxa coexistence in Daphnia hybrid systems. More generally, we suggest that if hybrids coexist in sympatry with parental taxa, the infection patterns as observed under natural conditions may be rather temporal and unstable. PMID:16822760

  5. Mating Behavior of Daphnia: Impacts of Predation Risk, Food Quantity, and Reproductive Phase of Females

    PubMed Central

    La, Geung-Hwan; Choi, Jong-Yun; Chang, Kwang-Hyeon; Jang, Min-Ho; Joo, Gea-Jae; Kim, Hyun-Woo

    2014-01-01

    High predation risk and food depletion lead to sexual reproduction in cyclically parthenogenetic Daphnia. Mating, the core of sexual reproduction, also occurs under these conditions. Assessment of the environmental conditions and alteration of mating efforts may aid in determining the success of sexual reproduction. Here, we evaluated the impacts of predation risk, food quantity, and reproductive phase of females on the mating behavior of Daphnia obtusa males including contact frequency and duration using video analysis. Mating–related behavior involved male–female contact (mating) as well as male–male contact (fighting). Mating frequency increased while unnecessary fighting decreased in the presence of predation risk. In addition, low food concentration reduced fighting between males. Males attempted to attach to sexual females more than asexual females, and fighting occurred more frequently in the presence of sexual females. Duration of mating was relatively long; however, males separated shortly after contact in terms of fighting behavior. Thus, assessment of environmental factors and primary sexing of mates were performed before actual contact, possibly mechanically, and precise sex discrimination was conducted after contact. These results suggest that mating in Daphnia is not a random process but rather a balance between predation risk and energetic cost that results in changes in mating and fighting strategies. PMID:25111600

  6. Effects of naphthalene on the hemoglobin concentration and oxygen uptake of daphnia magna

    SciTech Connect

    Crider, J.Y.; Wilhm, J.; Harman, H.J.

    1982-01-01

    In addition to acute testing for survival of Daphnia magna exposed to naphthalene, various physiological tests were made. Short term studies were conducted to calculate LC50 values and physiological responses. Daphnia of 24 h were fed initially 0.25 ml food/l and the pH, dissolved oxygen and temperature, conductivity, swimming movements, and the number of survivors were determined at 0, 24, and 48 h. These experiments were run at least three times and the dosage-mortality curves were determined by the use of probit and regression analyses. Physiological studies were made for concentrations of 1, 5, and 10 mg/l. Oxygen consumption of Daphnia was measured polarographically and a carboxyhemoglobin method was used to measure total hemoglobin. The hemoglobin concentrations of the treated organisms decreased from 102 nmoles/animal at 1 mg/l naphthalene to 67 nmoles/animal at 9 mg/l. Oxygen uptake decreased from 37 nmoles/animal/h at 1 mg/l to 28 nmoles/animal/h at8 mg/l. Results show that hemoglobin concentration and oxygen uptake may be useful tools in assessing water quality and its effects on the biota. (JMT)

  7. Experimental models of microcystin accumulation in Daphnia magna grazing on Planktothrix rubescens: implications for water management.

    PubMed

    Shams, Shiva; Cerasino, Leonardo; Salmaso, Nico; Dietrich, Daniel R

    2014-03-01

    In this study, we investigated the kinetic aspects of the microcystin (MC) transfer from Planktothrix rubescens to Daphnia magna by carrying out exposure experiments in small simple mesocosms. We hypothesized that higher fractions of toxic cyanobacteria in the diet of grazers would shift the balance towards a greater than linear, i.e. non-linear accumulation of MC in D. magna. This hypothesis was tested by exposing D. magna to varying initial densities of MC-producing P. rubescens. The evolving models of MC accumulation differed largely as a result of the duration of exposure and initial MC concentrations used. Within the first 24h of exposure, MC accumulation in D. magna was linear, irrespective of the initial densities of toxic P. rubescens and thus MC concentrations. After 48 h of exposure, MC accumulation in D. magna showed an exponential pattern, possibly due to a delayed digestion of P. rubescens and/or decreased MC detoxification capabilities when compared with higher ambient concentrations of MC. After 72 h toxin concentrations in Daphnia drop in all experiments as a consequence of the reduced cyanobacterial cells in the medium and the detoxification of MC within Daphnia. The results obtained suggest that in lakes with higher MC content and longer cyanobacterial bloom period MC accumulation in D. magna should be more pronounced than in mesotrophic lakes with lower MC content. The latter interpretation, however, should be verified investigating accumulation of MC both in larger mesocosms and in situ, in lakes of different trophic status.

  8. Use of daphnia magna to assess potentially contaminated buildings. Final report, April 1990-March 1991

    SciTech Connect

    Haley, M.V.; Kurnas, C.W.

    1992-06-01

    Random concrete core samples taken from a loading dock were used in determining the toxicity of concrete to Daphnia magna. The cores were ground to powder and analyzed for volatiles and chemical agents before being subjected to aquatic toxicology studies using Daphnia magna. Particle size, pH, and ion exchange mechanisms were investigated as par of methodology development. No effects were observed in daphnia exposed to concrete concentrations up to 4000 mg/L after the pH was adjusted. It was determined that an ion exchange reaction between sodium bicarbonate and concrete caused the water hardness to drop. Concrete spiked with sodium lauryl sulfate, copper sulfate, and Beta-aminoethylarylthiosulfonate were investigated to determine if concrete would alter the toxicity. The resulting EC50s were 17.2, 1.42, and 17.3 mg/L, respectively. The copper sulfate toxicity was reduced by two orders of magnitude. The changes in sodium lauryl sulfate and Beta-aminoethylarylthiosulfonate were not significant.

  9. Identification of multiple steroid hydroxylases in Daphnia magna and their modulation by xenobiotics

    SciTech Connect

    Baldwin, W.S.; LeBlanc, G.A. . Dept. of Toxicology)

    1994-07-01

    Steroid hydroxylase activities were characterized in Daphnia magna and evaluated for potential use as biomarkers of xenobiotic exposure. Microsomes prepared from Daphnia magna generated as single NADPH-dependent metabolite of [[sup 14]C] testosterone. However, intact daphnids excreted at least 10 polar metabolites of [[sup 14]C] testosterone into the test medium. Six of these metabolites were identified as 2[alpha]-, 16[beta]-, 6[beta]-, 6[alpha]-, 7[alpha]-, and 15[alpha]-[[sup 14]C]hydroxytestosterone. The unidentified metabolites are also presumed to be hydroxylated products of testosterone, based on their relative migrations during TLC. The inefficient metabolism of [[sup 14]C] testosterone during the in vitro microsomal incubations may have been due to the release of P450 inhibitors during microsome preparation. Exposure of daphnids to the P450 modulators phenobarbital, [beta]-naphthoflavone, piperonyl butoxide, and malathion differentially inhibited the steroid hydroxylase activities. Results from this study indicate that Daphnia magna expresses several P450 enzymes and that these enzymes are differentially modulated by xenobiotic exposure. Steroid hydroxylase activities may serve not only as a biomarker of toxicant exposure, but also as a predictor of toxicant effects involving perturbations of steroid hormone homeostasis.

  10. Effects of vertebrate hormones on development and sex determination in Daphnia magna.

    PubMed

    Kashian, Donna R; Dodson, Stanley I

    2004-05-01

    Daphnia (Crustacea) are extensively used as model organisms in ecotoxicology; however, little is known regarding their endocrine system. This study examines Daphnia vulnerability to vertebrate hormones. Twelve natural or synthetic vertebrate hormones were screened for activity on developmental and reproductive processes in Daphnia magna. Natural hormones tested included: beta-estradiol, gonadotropin, hydrocortisone, insulin, melatonin, progesterone, somatostatin, testosterone, and thyroxine at concentrations ranging from 1 to 100 microg/L. Synthetic hormones tested included diethylstilbestrol (estrogenic), R-1881 (androgen), and ICI-182,780 (antiestrogen); all hormones were screened with a 6-d assay. Additionally, progesterone, insulin, testosterone, and thyroxine were screened for 25 d. Diethylstilbestrol decreased D. magna growth rate while thyroxine increased it. Short-term testosterone exposure reduced D. magna fecundity; however, long-term exposure did not, potentially indicating testosterone hydroxylation with long-term exposure. Hormones commonly considered sex-hormones (estrogens and androgens) in vertebrates do not appear to control sexual differentiation in D. magna; however, several vertebrate hormones do affect reproduction and development in D. magna making D. magna a potentially useful tool in monitoring for the presence of these hormones or compounds that mimic them.

  11. Measurement of acute toxicity to Mysidopsis bahia using DaphniaQuant{reg_sign} instrument and protocol

    SciTech Connect

    Blankemeyer, J.T.; Nguyen, T.; Burks, S.L.

    1994-12-31

    DaphniaQuant{reg_sign} uses a fluorescent dye to permeate the cells of aquatic organisms. The technique has been used on frog embryos, fish embryos, and bovine erythrocytes. Two wavelengths of light are used to excite the fluorescent dye, Di-4-ANEPPS. The blue excitation wavelength measures the cell membrane potential while the yellow excitation wavelength measures the amount of dye loaded into the organisms. The authors applied the technique to the shrimp, Mysidopsis bahia, used in marine toxicity testing. The authors used from 1 to 10 shrimp, loaded into a 3 ml spectrofluorometry plastic cuvette. The fluorescent dye, Di-4-ANEPPS, was mixed with the 3 ml of ASW in the cuvette at a final Di-4ANEPPS concentration of 10{sub {minus}6} M. After a thirty minute incubation, the fluorescence of Di-4-ANEPPS was measured in the DaphniaQuant{reg_sign} instrument. A similar protocol was used to test various concentrations of standard assay chemicals and effluents. The test chemical was mixed with ASW and Di-4-ANEPPS and incubated with the shrimp for thirty minutes. After thirty minutes, the fluorescence was measured and compared to the fluorescence of the control shrimp. The authors found that the fluorescence from a single shrimp was detectable and gave similar toxicity data as did the replicates using 10 shrimp. They conclude that the DaphniaQuant{reg_sign} assay can be successfully adapted to marine organisms, particularly Mysidopsis bahia.

  12. Daphnia inhibits the emergence of spatial pattern in a simple consumer-resource system.

    PubMed

    Betini, Gustavo S; Avgar, Tal; McCann, Kevin S; Fryxell, John M

    2017-04-01

    Spatial self-organization can occur in many ecosystems with important effects on food web dynamics and the maintenance of biodiversity. The consumer-resource interaction is known to generate spatial patterning, but only a few empirical studies have investigated the effect of the consumer on resource distribution. Here we report results from a large aquatic mesocosm experiment used to investigate the effect of the consumer Daphnia magna on the distribution of its resource, the green algae Chlorella vulgaris. We maintained large tanks with capacity for 26 ,000 L with either algae or both algae and Daphnia in different temperature conditions. We found that the presence of D. magna inhibited spatial structure in algal distribution that arose as a consequence of increasing temperature. We conjecture that this homogenization effect might be caused by a combination of high mobility combined with high rates of algal consumption by Daphnia. Our study emphasizes the importance of both local constraints on growth and behavioral responses in either promoting or suppressing spatial self-organization in natural populations.

  13. A survey of well conserved families of C2H2 zinc-finger genes in Daphnia

    PubMed Central

    2010-01-01

    Background A recent comparative genomic analysis tentatively identified roughly 40 orthologous groups of C2H2 Zinc-finger proteins that are well conserved in "bilaterians" (i.e. worms, flies, and humans). Here we extend that analysis to include a second arthropod genome from the crustacean, Daphnia pulex. Results Most of the 40 orthologous groups of C2H2 zinc-finger proteins are represented by just one or two proteins within each of the previously surveyed species. Likewise, Daphnia were found to possess a similar number of orthologs for all of these small orthology groups. In contrast, the number of Sp/KLF homologs tends to be greater and to vary between species. Like the corresponding mammalian Sp/KLF proteins, most of the Drosophila and Daphnia homologs can be placed into one of three sub-groups: Class I-III. Daphnia were found to have three Class I proteins that roughly correspond to their Drosophila counterparts, dSP1, btd, CG5669, and three Class II proteins that roughly correspond to Luna, CG12029, CG9895. However, Daphnia have four additional KLF-Class II proteins that are most similar to the vertebrate KLF1/2/4 proteins, a subset not found in Drosophila. Two of these four proteins are encoded by genes linked in tandem. Daphnia also have three KLF-Class III members, one more than Drosophila. One of these is a likely Bteb2 homolog, while the other two correspond to Cabot and KLF13, a vertebrate homolog of Cabot. Conclusion Consistent with their likely roles as fundamental determinants of bilaterian form and function, most of the 40 groups of C2H2 zinc-finger proteins are conserved in kind and number in Daphnia. However, the KLF family includes several additional genes that are most similar to genes present in vertebrates but missing in Drosophila. PMID:20433734

  14. Potential impact of low-concentration silver nanoparticles on predator-prey interactions between predatory dragonfly nymphs and Daphnia magna as a prey.

    PubMed

    Pokhrel, Lok R; Dubey, Brajesh

    2012-07-17

    This study investigated the potential impacts of low-concentration citrate-coated silver nanoparticles (citrate-nAg; 2 μg L(-1) as total Ag) on the interactions of Daphnia magna Straus (as a prey) with the predatory dragonfly ( Anax junius : Odonata) nymph using the behavioral, survival, and reproductive end points. Four different toxicity bioassays were evaluated: (i) horizontal migration; (ii) vertical migration; (iii) 48 h survival; and (iv) 21 day reproduction; using four different treatment combinations: (i) Daphnia + citrate-nAg; (ii) Daphnia + predator; (iii) Daphnia + citrate-nAg + predator; and (iv) Daphnia only (control). Daphnia avoided the predators using the horizontal and vertical movements, indicating that Daphnia might have perceived a significant risk of predation. However, with citrate-nAg + predator treatment, Daphnia response did not differ from control in the vertical migration test, suggesting that Daphnia were unable to detect the presence of predator with citrate-nAg treatment and this may have potential implication on daphnids population structure owing to predation risk. The 48 h survival test showed a significant mortality of Daphnia individuals in the presence of predators, with or without citrate-nAg, in the test environment. Average reproduction of daphnids increased by 185% with low-concentration citrate-nAg treatment alone but was severely compromised in the presence of predators (decreased by 91.3%). Daphnia reproduction was slightly enhanced by approximately 128% with citrate-nAg + predator treatment. Potential mechanisms of these differential effects of low-concentration citrate-nAg, with or without predators, are discussed. Because silver dissolution was minimal, the observed toxicity could not be explained by dissolved Ag alone. These findings offer novel insights into how exposure to low-concentration silver nanoparticles could influence predator-prey interactions in the fresh water systems.

  15. Climate-driven warming during spring destabilises a Daphnia population: a mechanistic food web approach.

    PubMed

    Wagner, Annekatrin; Benndorf, Jürgen

    2007-03-01

    Temperature-driven changes in interactions between populations are crucial to the estimation of the impact of global warming on aquatic food webs. We analysed inter-annual variability in two data sets from Bautzen reservoir, Germany. In a long-term data set (1981-1999) we examined the pelagic phenology of Daphnia galeata, a keystone species, the invertebrate predator Leptodora kindtii, phytoplankton and Secchi depth in relation to water temperature and the North Atlantic Oscillation index. In a short-term data set (1995-1998) we examined food web relations, particularly the consumption of D. galeata by young-of-the-year (YOY) percids and L. kindtii and rates of population change of D. galeata (abundance, recruitment pattern and non-consumptive mortality). The start of the clear-water stage (CWS) was correlated with winter temperatures. It started 5.8 days earlier per degree warming after warm winters (mean January-March temperature>or=2.5 degrees C) compared to cold winters (mean temperature<2.5 degrees C). However, the end of the CWS remained relatively constant. Predation by L. kindtii and YOY percids on D. galeata started distinctly earlier, i.e. by 13.0 and 6.5 days per degree warming, respectively, in years when the average May temperature was high (>or=14 degrees C) compared to years when it was low (<14 degrees C). Significant reductions of Daphnia abundance in midsummer occurred only in years in which the mean May temperature exceeded 14 degrees C. This temperature regime resulted in a match of over-exploitation of food resources by Daphnia during the CWS and strong predation by YOY percids and L. kindtii. Consumptive mortality increased at higher rates with a rise in temperature than net recruitment, resulting in lower Daphnia densities at the end of the CWS. Our data suggest that even low warming by 1.7 degrees C during a short, but critical seasonal period, resulting in the coincidence of two or more factors adversely affecting a keystone species, such

  16. Toxicity tests based on predator-prey and competitive interactions between freshwater macroinvertebrates

    SciTech Connect

    Taylor, E.J.; Blockwell, S.J.; Pascoe, D.

    1994-12-31

    Simple multi-species toxicity tests based on the predation of Daphnia magna Straus by Hydra oligactis (Pallas) and competition between Gammarus pulex (L.) and Asellus aquaticus (L.) were used to determine the effects of three reference chemicals. Criteria examined included functional responses; time to first captures; handling times (predator/prey systems) and co-existence and growth. The tests which proved most practicable and sensitive (lowest observed effects 0.1, 21, and 80 {micro}g/l for lindane, copper and 3,4 dichloroaniline, respectively) were: (1) predator-prey tests: determining changes in the size-structure of predated D. magna populations and (2) competition tests: measuring the feeding rate of G. pulex competing with A. aquaticus, using a bioassay based on the time-response analysis of the consumption of Artemia salina eggs. The concentration of a chemical which affected particular response criteria was fond to depend on the test system employed. Results of the tests indicated that effects were often not dose-related and that a given criterion could be variously affected by different test concentrations. The complex pattern of responses may be explained in terms of the differential sensitivity of the interacting species and perhaps subtle alteration in strategies. The sensitivity of the bioassay endpoints is compared to those of a range of single species tests, and their value for predicting the impact pollutants may have upon natural freshwater ecosystems is discussed.

  17. Comparison of the sensitivity of seven marine and freshwater bioassays as regards antidepressant toxicity assessment.

    PubMed

    Minguez, Laetitia; Di Poi, Carole; Farcy, Emilie; Ballandonne, Céline; Benchouala, Amira; Bojic, Clément; Cossu-Leguille, Carole; Costil, Katherine; Serpentini, Antoine; Lebel, Jean-Marc; Halm-Lemeille, Marie-Pierre

    2014-11-01

    The hazards linked to pharmaceutical residues like antidepressants are currently a major concern of ecotoxicology because they may have adverse effects on non-target aquatic organisms. Our study assesses the ecotoxicity of three antidepressants (fluoxetine, sertraline and clomipramine) using a battery of marine and freshwater species representing different trophic levels, and compares the bioassay sensitivity levels. We selected the following bioassays: the algal growth inhibition test (Skeletonema marinoi and Pseudokirchneriella subcapitata), the microcrustacean immobilization test (Artemia salina and Daphnia magna), development and adult survival tests on Hydra attenuata, embryotoxicity and metamorphosis tests on Crassostrea gigas, and in vitro assays on primary cultures of Haliotis tuberculata hemocytes. The results showed high inter-species variability in EC50-values ranging from 43 to 15,600 µg/L for fluoxetine, from 67 to 4,400 µg/L for sertraline, and from 4.70 µg/L to more than 100,000 µg/L for clomipramine. Algae (S. marinoi and P. subcapitata) and the embryo-larval stages of the oyster C. gigas were the most sensitive taxa. This raises an issue due to their ecological and/or economic importance. The marine crustacean A. salina was the least sensitive species. This difference in sensitivity between bioassays highlights the importance of using a test battery.

  18. Pathogenic agents in freshwater resources

    NASA Astrophysics Data System (ADS)

    Geldreich, Edwin E.

    1996-02-01

    Numerous pathogenic agents have been found in freshwaters used as sources for water supplies, recreational bathing and irrigation. These agents include bacterial pathogens, enteric viruses, several protozoans and parasitic worms more common to tropical waters. Although infected humans are a major source of pathogens, farm animals (cattle, sheep, pigs), animal pets (dogs, cats) and wildlife serve as significant reservoirs and should not be ignored. The range of infected individuals within a given warm-blooded animal group (humans included) may range from 1 to 25%. Survival times for pathogens in the water environment may range from a few days to as much as a year (Ascaris, Taenia eggs), with infective dose levels varying from one viable cell for several primary pathogenic agents to many thousands of cells for a given opportunistic pathogen.As pathogen detection in water is complex and not readily incorporated into routine monitoring, a surrogate is necessary. In general, indicators of faecal contamination provide a positive correlation with intestinal pathogen occurrences only when appropriate sample volumes are examined by sensitive methodology.Pathways by which pathogens reach susceptible water users include ingestion of contaminated water, body contact with polluted recreational waters and consumption of salad crops irrigated by polluted freshwaters. Major contributors to the spread of various water-borne pathogens are sewage, polluted surface waters and stormwater runoff. All of these contributions are intensified during periods of major floods. Several water-borne case histories are cited as examples of breakdowns in public health protection related to water supply, recreational waters and the consumption of contaminated salad crops. In the long term, water resource management must focus on pollution prevention from point sources of waste discharges and the spread of pathogens in watershed stormwater runoff.

  19. Controlling Harmful Cyanobacteria: Taxa-Specific Responses of Cyanobacteria to Grazing by Large-Bodied Daphnia in a Biomanipulation Scenario.

    PubMed

    Urrutia-Cordero, Pablo; Ekvall, Mattias K; Hansson, Lars-Anders

    2016-01-01

    Lake restoration practices based on reducing fish predation and promoting the dominance of large-bodied Daphnia grazers (i.e., biomanipulation) have been the focus of much debate due to inconsistent success in suppressing harmful cyanobacterial blooms. While most studies have explored effects of large-bodied Daphnia on cyanobacterial growth at the community level and/or on few dominant species, predictions of such restoration practices demand further understanding on taxa-specific responses in diverse cyanobacterial communities. In order to address these questions, we conducted three grazing experiments during summer in a eutrophic lake where the natural phytoplankton community was exposed to an increasing gradient in biomass of the large-bodied Daphnia magna. This allowed evaluating taxa-specific responses of cyanobacteria to Daphnia grazing throughout the growing season in a desired biomanipulation scenario with limited fish predation. Total cyanobacterial and phytoplankton biomasses responded negatively to Daphnia grazing both in early and late summer, regardless of different cyanobacterial densities. Large-bodied Daphnia were capable of suppressing the abundance of Aphanizomenon, Dolichospermum, Microcystis and Planktothrix bloom-forming cyanobacteria. However, the growth of the filamentous Dolichospermum crassum was positively affected by grazing during a period when this cyanobacterium dominated the community. The eutrophic lake was subjected to biomanipulation since 2005 and nineteen years of lake monitoring data (1996-2014) revealed that reducing fish predation increased the mean abundance (50%) and body-size (20%) of Daphnia, as well as suppressed the total amount of nutrients and the growth of the dominant cyanobacterial taxa, Microcystis and Planktothrix. Altogether our results suggest that lake restoration practices solely based on grazer control by large-bodied Daphnia can be effective, but may not be sufficient to control the overgrowth of all

  20. Controlling Harmful Cyanobacteria: Taxa-Specific Responses of Cyanobacteria to Grazing by Large-Bodied Daphnia in a Biomanipulation Scenario

    PubMed Central

    Urrutia-Cordero, Pablo; Ekvall, Mattias K.; Hansson, Lars-Anders

    2016-01-01

    Lake restoration practices based on reducing fish predation and promoting the dominance of large-bodied Daphnia grazers (i.e., biomanipulation) have been the focus of much debate due to inconsistent success in suppressing harmful cyanobacterial blooms. While most studies have explored effects of large-bodied Daphnia on cyanobacterial growth at the community level and/or on few dominant species, predictions of such restoration practices demand further understanding on taxa-specific responses in diverse cyanobacterial communities. In order to address these questions, we conducted three grazing experiments during summer in a eutrophic lake where the natural phytoplankton community was exposed to an increasing gradient in biomass of the large-bodied Daphnia magna. This allowed evaluating taxa-specific responses of cyanobacteria to Daphnia grazing throughout the growing season in a desired biomanipulation scenario with limited fish predation. Total cyanobacterial and phytoplankton biomasses responded negatively to Daphnia grazing both in early and late summer, regardless of different cyanobacterial densities. Large-bodied Daphnia were capable of suppressing the abundance of Aphanizomenon, Dolichospermum, Microcystis and Planktothrix bloom-forming cyanobacteria. However, the growth of the filamentous Dolichospermum crassum was positively affected by grazing during a period when this cyanobacterium dominated the community. The eutrophic lake was subjected to biomanipulation since 2005 and nineteen years of lake monitoring data (1996–2014) revealed that reducing fish predation increased the mean abundance (50%) and body-size (20%) of Daphnia, as well as suppressed the total amount of nutrients and the growth of the dominant cyanobacterial taxa, Microcystis and Planktothrix. Altogether our results suggest that lake restoration practices solely based on grazer control by large-bodied Daphnia can be effective, but may not be sufficient to control the overgrowth of all

  1. Daphnia hybridization along ecological gradients in pelagic environments: the potential for the presence of hybrid zones in plankton.

    PubMed

    Petrusek, Adam; Seda, Jaromir; Machácek, Jiri; Ruthova, Stepánka; Smilauer, Petr

    2008-09-12

    The relative homogeneity of pelagic environments has been regarded as the reason for the absence of hybrid zones for hybridizing planktonic Daphnia (Crustacea: Cladocera); occasional dominance of interspecific hybrids over parental species was explained by their temporal superiority in fluctuating environments. However, water bodies with spatially varying environmental conditions might facilitate the formation of hybrid zones in plankton. We studied the distribution of species and hybrids of the Daphnia longispina complex in 11 canyon-shaped reservoirs, localities characterized by horizontal environmental gradients (particularly of food supply and size-selective predation); we also analysed patterns of carapace size and fecundity among coexisting taxa. Spatial distribution of taxa agreed with their ecological characteristics; those showing different affinities along longitudinal reservoir profiles differed in size according to the presumed fish predation gradient. Only hybrids of Daphnia galeata with Daphnia cucullata and D. longispina (=hyalina) were recorded. The latter two species preferred opposite ends of gradients, such spatial segregation probably explaining the absence of their hybrids. Distributional patterns were relatively stable in two consecutive summers, apart from a substantial decline of D. galeata X cucullata in the second year. The observed pattern of a hybrid-dominated zone in intermediate conditions suggests that local Daphnia hybrid zones may indeed form within reservoirs.

  2. Lifetime response of contemporary versus resurrected Daphnia galeata Sars (Crustacea, Cladocera) to Cu(II) chronic exposure.

    PubMed

    Piscia, Roberta; Colombini, Maria; Ponti, Benedetta; Bettinetti, Roberta; Monticelli, Damiano; Rossi, Valeria; Manca, Marina

    2015-01-01

    Resurrecting legacy lineages of organisms from sediment cores of known geological age allows us to understand how environmental change can cause selection pressures that constrain the variation of populations over time. We quantified the lifetime tolerance and effects of Cu(II) exposure on Daphnia galeata in a polluted subalpine lake by comparing extant individuals with those resurrected from ephippia extracted from ca. 30-years-old sediments. Laboratory experiments were conducted using two Cu(II) concentrations, 40 and 10 µg L(-1), corresponding to the levels recorded in the lake, during chemical recovery, when Daphnia first re-appeared and succeeded. Contemporary Daphnia were unable to survive after the 10th day at either of the Cu(II) concentrations, and were unable to successfully reproduce. Daphnia cohorts from the past performed better in low Cu(II) concentrations than in copper-free, control conditions. The copper-adapted, tolerant Daphnia strains grew faster under non-toxic conditions, but were unable to survive new pollution events.

  3. A critical review of the current taxonomy of the genus Daphnia O. F. Müller, 1785 (Anomopoda, Cladocera).

    PubMed

    Kotov, Alexey A

    2015-01-19

    The genus Daphnia O. F. Müller, 1785 (Anomopoda, Cladocera) has become a model genus for ecological, toxicological, and evolutionary studies. At the same time, Daphnia is a well-known example of a genus with a confused taxonomy. This review aims to identify the main sources of confusion (natural and human-caused) for the current taxonomy of Daphnia. A complete check-list of all species-group names of Daphnia was built using the available literature sources. I graphed the total number of taxa and number of valid taxa described during each year, and estimated a curve of accumulation of formal taxa from year to year. Four main periods in the history of Daphnia taxonomy were recognized, with the latest decades showing an increased rate of valid taxa to more than 50%. Overall, only 24 % of 361 known taxa of species rank are valid. A failure to find real, sometimes fine-scale diagnostic characters, led to a tradition of pseudo-taxonomy based mainly on the body shape and other phenotypically plastic characters, e.g. associated with defensive structures. I recommend revising the suite of taxonomically informative characters by emphasizing the anatomical details of males and thoracic limbs of both males and females. Such a revision of global scale, should be conducted in close coordination with phylogenetic studies. But this revision is impossible without accurate redescriptions of all previously described taxa, and a continuous step-by-step resolving of taxonomic problems in each species group. 

  4. Fatty acid profiling reveals seasonal and spatial shifts in zooplankton diet in a temperate estuary

    NASA Astrophysics Data System (ADS)

    Gonçalves, A. M. M.; Azeiteiro, U. M.; Pardal, M. A.; De Troch, M.

    2012-08-01

    Fatty acids composition of copepod and cladoceran species and their possible food sources was investigated in the Mondego estuary (southern Europe) in order to explain the seasonal variation of the small copepods Acartia clausi, Acartia tonsa, Copidodiaptomus numidicus, Temora longicornis and the freshwater cladoceran Daphnia longispina. A total of 12 zooplankton species (7 marine, 2 estuarine and 3 freshwater species) were studied. A multivariate analysis revealed a clear seasonal distribution of zooplankton species in terms of fatty acids composition and abundance, with winter and spring zooplankton species showing maximal concentrations and diversity of total fatty acids. These findings underline the role of lipids as storage during the colder seasons in a highly variable environment like an estuary. Estuarine and freshwater species showed a more diverse array of saturated and unsaturated fatty acids rather than marine species, except for Centropages typicus. Fatty acids markers of trophic position indicated the presence of two trophic levels: copepod species were primarily omnivorous, whereas cladocerans showed to be herbivorous. Our results suggest that feeding patterns of plankton change spatially and temporally, reflecting the shifts in dominance between diatoms and flagellates as well as between dinoflagellates/diatoms and small animals.

  5. Endemism and long distance dispersal in the waterfleas of Easter Island.

    PubMed

    Damme, Kay Van

    2016-08-22

    Easter Island is known for a depauperate terrestrial and aquatic biota. The discovery of new taxa is unusual, even among the island's micro-invertebrates. A new cladoceran, Ovalona pascua sp. nov. (Crustacea: Cladocera: Anomopoda: Chydoridae), is described from freshwater environments. The chydorid, the only known extant cladoceran on the island, is the dominant aquatic invertebrate in the surface waters. Based on detailed morphological comparison, including a character similarity matrix applied across the species in the genus (12 characters/17 spp), the new taxon is proposed here as an insular endemic with affinities in the East (New World). The revision challenges the theory that invasive zooplankton species were introduced from the subantarctic islands during the 18th century. Human introduction is not the main mechanism through which cladocerans could have arrived on Easter Island. Late Pleistocene - Early Holocene fossils in Cañellas-Boltà et al. (2012) from cores in Rano Raraku Lake are identified here as Daphnia O.F. Müller, 1785 (subgenus Ctenodaphnia Dybowski & Grochowski, 1895). The establishment of Daphnia before human colonization on Easter Island provides strong proof of successful long distance dispersal by ephippia over thousands of kilometers of open sea.

  6. 40 CFR 35.1605-3 - Publicly owned freshwater lake.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 1 2010-07-01 2010-07-01 false Publicly owned freshwater lake. 35.1605... Owned Freshwater Lakes § 35.1605-3 Publicly owned freshwater lake. A freshwater lake that offers public... maintaining the public access and recreational facilities of this lake or other publicly owned...

  7. Temporal assessment of copper speciation, bioavailability and toxicity in UK freshwaters using chemical equilibrium and biotic ligand models: Implications for compliance with copper environmental quality standards.

    PubMed

    Lathouri, Maria; Korre, Anna

    2015-12-15

    Although significant progress has been made in understanding how environmental factors modify the speciation, bioavailability and toxicity of metals such as copper in aquatic environments, the current methods used to establish water quality standards do not necessarily consider the different geological and geochemical characteristics of a given site and the factors that affect copper fate, bioavailability potential and toxicity. In addition, the temporal variation in the concentration and bioavailable metal fraction is also important in freshwater systems. The work presented in this paper illustrates the temporal and seasonal variability of a range of water quality parameters, and Cu speciation, bioavailability and toxicity at four freshwaters sites in the UK. Rivers Coquet, Cree, Lower Clyde and Eden (Kent) were selected to cover a broad range of different geochemical environments and site characteristics. The monitoring data used covered a period of around six years at almost monthly intervals. Chemical equilibrium modelling was used to study temporal variations in Cu speciation and was combined with acute toxicity modelling to assess Cu bioavailability for two aquatic species, Daphnia magna and Daphnia pulex. The estimated copper bioavailability, toxicity levels and the corresponding ecosystem risks were analysed in relation to key water quality parameters (alkalinity, pH and DOC). Although copper concentrations did not vary much during the sampling period or between the seasons at the different sites; copper bioavailability varied markedly. In addition, through the chronic-Cu BLM-based on the voluntary risk assessment approach, the potential environmental risk in terms of the chronic toxicity was assessed. A much higher likelihood of toxicity effects was found during the cold period at all sites. It is suggested that besides the metal (copper) concentration in the surface water environment, the variability and seasonality of other important water quality

  8. The anticancer drug metabolites endoxifen and 4-hydroxy-tamoxifen induce toxic effects on Daphnia pulex in a two-generation study.

    PubMed

    Borgatta, Myriam; Decosterd, Laurent-Arthur; Waridel, Patrice; Buclin, Thierry; Chèvre, Nathalie

    2015-07-01

    Although pharmaceutical metabolites are found in the aquatic environment, their toxicity on living organisms is poorly studied in general. Endoxifen and 4-hydroxy-tamoxifen (4OHTam) are two metabolites of the widely used anticancer drug tamoxifen for the prevention and treatment of breast cancers. Both metabolites have a high pharmacological potency in vertebrates, attributing prodrug characteristics to tamoxifen. Tamoxifen and its metabolites are body-excreted by patients, and the parent compound is found in sewage treatment plan effluents and natural waters. The toxicity of these potent metabolites on non-target aquatic species is unknown, which forces environmental risk assessors to predict their toxicity on aquatic species using knowledge on the parent compounds. Therefore, the aim of this study was to assess the sensitivity of two generations of the freshwater microcrustacean Daphnia pulex towards 4OHTam and endoxifen. Two chronic tests of 4OHTam and endoxifen were run in parallel and several endpoints were assessed. The results show that the metabolites 4OHTam and endoxifen induced reproductive and survival effects. For both metabolites, the sensitivity of D. pulex increased in the second generation. The intrinsic rate of natural increase (r) decreased with increasing 4OHTam and endoxifen concentrations. The No-Observed Effect Concentrations (NOECs) calculated for the reproduction of the second generation exposed to 4OHTam and endoxifen were <1.8 and 4.3 μg/L, respectively, whereas the NOECs that were calculated for the intrinsic rate of natural increase were <1.8 and 0.4 μg/L, respectively. Our study raises questions about prodrug and active metabolites in environmental toxicology assessments of pharmaceuticals. Our findings also emphasize the importance of performing long-term experiments and considering multi-endpoints instead of the standard reproduction outcome.

  9. Transition from Environmental to Partial Genetic Sex Determination in Daphnia through the Evolution of a Female-Determining Incipient W Chromosome.

    PubMed

    Reisser, Céline M O; Fasel, Dominique; Hürlimann, Evelin; Dukič, Marinela; Haag-Liautard, Cathy; Thuillier, Virginie; Galimov, Yan; Haag, Christoph R

    2016-12-21

    Sex chromosomes can evolve during the evolution of genetic sex determination (GSD) from environmental sex determination (ESD). Despite theoretical attention, early mechanisms involved in the transition from ESD to GSD have yet to be studied in nature. No mixed ESD-GSD animal species have been reported, except for some species of Daphnia, small freshwater crustaceans in which sex is usually determined solely by the environment, but in which a dominant female sex-determining locus is present in some populations. This locus follows Mendelian single-locus inheritance, but has otherwise not been characterized genetically. We now show that the sex-determining genomic region maps to the same low-recombining peri-centromeric region of linkage group 3 (LG3) in three highly divergent populations of D. magna, and spans 3.6 Mb. Despite low levels of recombination, the associated region contains signs of historical recombination, suggesting a role for selection acting on several genes thereby maintaining linkage disequilibrium among the 36 associated SNPs. The region carries numerous genes involved in sex differentiation in other taxa, including transformer2 and sox9 Taken together, the region determining the genetic females shows characteristics of a sex-related supergene, suggesting that LG3 is potentially an incipient W chromosome despite the lack of significant additional restriction of recombination between Z and W. The occurrence of the female-determining locus in a pre-existing low recombining region illustrates one possible form of recombination suppression in sex chromosomes. D. magna is a promising model for studying the evolutionary transitions from ESD to GSD and early sex chromosome evolution.

  10. Co-exposure of ZnO nanoparticles and UV radiation to Daphnia magna and Danio rerio: Combined effects rather than protection.

    PubMed

    Azevedo, Sofia L; Ribeiro, Fabianne; Jurkschat, Kerstin; Soares, Amadeu M V M; Loureiro, Susana

    2016-02-01

    The application of nanoparticles (NPs) in consumer products has been increasing over the past few years. Their release into the environment is likely to happen at any stage of production or during the use of products containing NPs. Zinc oxide NPs (ZnO-NP) are among the most-used NPs on the market due to its intrinsic properties, such as ultraviolet (UV) absorption. The aim of the present study was to assess the combined effects of ZnO-NP and UV radiation on 2 freshwater species: Daphnia magna and Danio rerio. The initial hypothesis was that the presence of ZnO-NP in the aquatic media would decrease the damaging effects of UV radiation for both species. The endpoints assessed for D. magna were immobilization, feeding inhibition, and reproduction output. For D. rerio, egg development was studied during 96 h and mortality, hatching delay, and abnormal development were the endpoints recorded. Combined exposures were designed based on the single toxicity of both stressors and analyzed based on the independent action concept and exploring possible deviations for synergism/antagonism, dose level, and dose ratio. Combined exposures with D. magna induced synergism on reproduction, decreasing the number of neonates produced more than expected based on both stressors' individual toxicity. Single exposures of D. rerio embryos to both stressors induced negative effects. The combined exposures caused a dose-ratio deviation pattern on mortality and hatching, with a synergism observed when ZnO-NP was the dominant stressor, changing to antagonism when UV radiation dominated the combined exposure. Regarding the results attained, studying ZnO toxicity under laboratory conditions may underestimate the risks when considering the potential interaction on effects when combined with UV radiation.

  11. Bioassessment Methodologies for the Regulatory Testing of Freshwater Dredged Material. Phase 2

    DTIC Science & Technology

    1990-03-01

    assessments. Phase II comment: Recommended animals for acute and life cycle testing are the daphnid Daphnia magna , the midge Chironomus tentans, and the... Daphnia magna , represents organisms inhabiting the near-bottom and water-column environment; the other species, Chironomus tentans, represents the...sediments using Daphnia magna and Chironomus tentans in a 48- hr period. Each treatment would be replicated four times using five D. magna and five C

  12. Native Freshwater Fish and Mussel Species Richness

    EPA Pesticide Factsheets

    These data represent predicted current distributions of all native freshwater fish and freshwater mussels in the Middle-Atlantic region. The data are available for both 8-digit HUCs and EMAP hexagons and represent total species counts for each spatial unit. More information about these resources, including the variables used in this study, may be found here: https://edg.epa.gov/data/Public/ORD/NERL/ReVA/ReVA_Data.zip.

  13. Estimated freshwater withdrawals in Washington, 2010

    USGS Publications Warehouse

    Lane, Ron C.; Welch, Wendy B.

    2015-03-18

    The amount of public- and self-supplied water used for domestic, irrigation, livestock, aquaculture, industrial, mining, and thermoelectric power was estimated for state, county, and eastern and western regions of Washington during calendar year 2010. Withdrawals of freshwater for offstream uses were estimated to be about 4,885 million gallons per day. The total estimated freshwater withdrawals for 2010 was approximately 15 percent less than the 2005 estimate because of decreases in irrigation and thermoelectric power withdrawals.

  14. Freshwater Commercial Bycatch: an Understated Conservation Problem

    SciTech Connect

    Raby, Graham D.; Colotelo, Alison HA; Blouin-Demers, Gabriel; Cooke, Steven J.

    2011-04-01

    Commercial fisheries bycatch in marine systems has been regarded as a global conservation concern by environmental groups, scientists, government, and the public for decades. Fortunately, some headway has been made to mitigate the negative impacts of bycatch in marine environments. In a survey of the literature, we found that despite freshwater commercial fisheries yields comprising 11% of the global commercial catch, bycatch research focusing on freshwater commercial fisheries represented only {approx}3% of the total bycatch literature. This paucity of research is particularly alarming given that freshwater animals and habitats are some of the world's most imperiled. The limited inland bycatch literature that does exist includes examples of population declines attributed to commercial bycatch (e.g., freshwater dolphins in the Yangtze River in China) and illustrates that in some systems bycatch can be substantial (e.g., lake trout bycatch in the Laurentian Great Lakes). Encouraging results from the marine realm can serve as models for bycatch research in freshwater, and lead to measurable gains in conservation of freshwater ecosystems. We summarize existing work on inland bycatch in an effort to draw attention to this understated and understudied conservation problem.

  15. [Daphnia magna Straus: a test object for the pharmacological evaluation of GABA-ergic drugs in the whole organism].

    PubMed

    Tonkopiĭ, V D; Podosinovikova, N P; Zagrebin, A O; Sherstneva, L A; Petrov, V V; Mukovskiĭ, L A; Dolgo-Saburov, V B

    2005-01-01

    The toxicity of a series of GABAlytics (11 drugs) representing different pharmacological groups was evaluated in comparative experiments on Daphnia magna Straus and white mice. A high degree of correlation was established between the toxicity of GABA antagonists studied in daphnia and mice. The pharmacological analysis of the interaction of agonists and antagonists of GABA/benzodiazepine/ionophore-receptor complex--the competitive ligands for various binding sites--was carried out. It is suggested that the ability of GABA agonists to prevent the action of GABA antagonists in whole organism is mainly det