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Sample records for heterosigma akashiwo raphidophyceae

  1. Recurrent blooms of Heterosigma akashiwo (Raphidophyceae in the Piraquê Channel, Rodrigo de Freitas Lagoon, southeast Brazil

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    S Branco

    Full Text Available Six blooms of Heterosigma akashiwo(Raphidophyceae were observed from March 2007 through March 2008 in the Rodrigo de Freitas Lagoon, a semi-confined eutrophic system located in Rio de Janeiro state, southeast Brazil. Vegetative cells of H. akashiwo analysed by optical and electron microscopy showed morphology as described in the literature. The blooms (2.8 × 104 to 4 × 108 cell.L–1 were restricted to the middle section of the Piraquê Channel, which is situated in the northeastern part of the lagoon and receives freshwater inflow. The salinity of subsurface water and the channel depth showed significant negative correlations with H. akashiwo abundances, and appeared to restrict the blooms to this compartment of the lagoon. No fish mortality was associated with the H. akashiwo blooms, nor were brevetoxins detected in a cell extract obtained from the bloom observed on 19 March 2007.

  2. Chloroplast His-to-Asp signal transduction: a potential mechanism for plastid gene regulation in Heterosigma akashiwo (Raphidophyceae

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    Jacobs Michael A

    2007-05-01

    Full Text Available Abstract Background Maintenance of homeostasis requires that an organism perceive selected physical and chemical signals within an informationally dense environment. Functionally, an organism uses a variety of signal transduction arrays to amplify and convert these perceived signals into appropriate gene transcriptional responses. These changes in gene expression serve to modify selective metabolic processes and thus optimize reproductive success. Here we analyze a chloroplast-encoded His-to-Asp signal transduction circuit in the stramenopile Heterosigma akashiwo (Hada Hada ex Y. Hara et Chihara [syn. H. carterae (Hulburt F.J.R. Taylor]. The presence, structure and putative function of this protein pair are discussed in the context of their evolutionary homologues. Results Bioinformatic analysis of the Heterosigma akashiwo chloroplast genome sequence revealed the presence of a single two-component His-to-Asp (designated Tsg1/Trg1 pair in this stramenopile (golden-brown alga. These data represent the first documentation of a His-to-Asp array in stramenopiles and counter previous reports suggesting that such regulatory proteins are lacking in this taxonomic cluster. Comparison of the 43 kDa H. akashiwo Tsg1 with bacterial sensor kinases showed that the algal protein exhibits a moderately maintained PAS motif in the sensor kinase domain as well as highly conserved H, N, G1 and F motifs within the histidine kinase ATP binding site. Molecular modelling of the 27 kDa H. akashiwo Trg1 regulator protein was consistent with a winged helix-turn-helix identity – a class of proteins that is known to impact gene expression at the level of transcription. The occurrence of Trg1 protein in actively growing H. akashiwo cells was verified by Western analysis. The presence of a PhoB-like RNA polymerase loop in Trg1 and its homologues in the red-algal lineage support the hypothesis that Trg1 and its homologues interact with a sigma 70 (σ70 subunit (encoded by

  3. The Marine Microalga, Heterosigma akashiwo, Converts Industrial Waste Gases into Valuable Biomass

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, Jennifer J., E-mail: jen@udel.edu [College of Earth, Ocean, and Environment, University of Delaware, Lewes, DE (United States); Bianco, Colleen M. [Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL (United States); Miller, Katherine R. [Department of Chemistry, Salisbury University, Salisbury, MD (United States); Coyne, Kathryn J. [College of Earth, Ocean, and Environment, University of Delaware, Lewes, DE (United States)

    2015-03-16

    Heterosigma akashiwo is an excellent candidate for growth on industrial emissions since this alga has the ability to metabolize gaseous nitric oxide (NO) into cellular nitrogen via a novel chimeric protein (NR2-2/2HbN) and also tolerates wide fluctuations in temperature, salinity, and nutrient conditions. Here, we evaluated biomass productivity and composition, photosynthetic efficiency, and expression of NR2-2/2HbN for Heterosigma growing on simulated flue gas containing 12% CO{sub 2} and 150 ppm NO. Biomass productivity of Heterosigma more than doubled in flue gas conditions compared to controls, reflecting a 13-fold increase in carbohydrate and a 2-fold increase in protein productivity. Lipid productivity was not affected by flue gas and the valuable omega-3 fatty acids, eicosapentaenoic acid and docosahexaenoic acid, constituted up to 16% of total fatty acid methyl esters. Photochemical measurements indicated that photosynthesis in Heterosigma is not inhibited by high CO{sub 2} and NO concentrations, and increases in individual fatty acids in response to flue gas were driven by photosynthetic requirements. Growth rates and maximum cell densities of Heterosigma grown on simulated flue gas without supplemental nitrogen, along with a significant increase in NR2-2/2HbN transcript abundance in response to flue gas, demonstrated that nitrogen derived from NO gas is biologically available to support enhanced CO{sub 2} fixation. Together, these results illustrate the robustness of this alga for commercial-scale biomass production and bioremediation of industrial emissions.

  4. The Marine Microalga, Heterosigma akashiwo, Converts Industrial Waste Gases into Valuable Biomass

    International Nuclear Information System (INIS)

    Stewart, Jennifer J.; Bianco, Colleen M.; Miller, Katherine R.; Coyne, Kathryn J.

    2015-01-01

    Heterosigma akashiwo is an excellent candidate for growth on industrial emissions since this alga has the ability to metabolize gaseous nitric oxide (NO) into cellular nitrogen via a novel chimeric protein (NR2-2/2HbN) and also tolerates wide fluctuations in temperature, salinity, and nutrient conditions. Here, we evaluated biomass productivity and composition, photosynthetic efficiency, and expression of NR2-2/2HbN for Heterosigma growing on simulated flue gas containing 12% CO 2 and 150 ppm NO. Biomass productivity of Heterosigma more than doubled in flue gas conditions compared to controls, reflecting a 13-fold increase in carbohydrate and a 2-fold increase in protein productivity. Lipid productivity was not affected by flue gas and the valuable omega-3 fatty acids, eicosapentaenoic acid and docosahexaenoic acid, constituted up to 16% of total fatty acid methyl esters. Photochemical measurements indicated that photosynthesis in Heterosigma is not inhibited by high CO 2 and NO concentrations, and increases in individual fatty acids in response to flue gas were driven by photosynthetic requirements. Growth rates and maximum cell densities of Heterosigma grown on simulated flue gas without supplemental nitrogen, along with a significant increase in NR2-2/2HbN transcript abundance in response to flue gas, demonstrated that nitrogen derived from NO gas is biologically available to support enhanced CO 2 fixation. Together, these results illustrate the robustness of this alga for commercial-scale biomass production and bioremediation of industrial emissions.

  5. Inactivation of Heterosigma akashiwo in ballast water by circular orifice plate-generated hydrodynamic cavitation.

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    Feng, Daolun; Zhao, Jie; Liu, Tian

    2016-01-01

    The discharge of alien ballast water is a well-known, major reason for marine species invasion. Here, circular orifice plate-generated hydrodynamic cavitation was used to inactivate Heterosigma akashiwo in ballast water. In comparison with single- and multihole orifice plates, the conical-hole orifice plate yielded the highest inactivation percentage, 51.12%, and consumed only 6.84% energy (based on a 50% inactivation percentage). Repeating treatment, either using double series-connection or circling inactivation, elevated the inactivation percentage, yet consumed much more energy. The results indicate that conical-hole-generated hydrodynamic cavitation shows great potential as a pre-inactivation method for ballast water treatment.

  6. Microflora in the Soft Tissue of the Pacific Oyster Crassostrea gigas Exposed to the Harmful Microalga Heterosigma akashiwo.

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    Takenaka, Shinkuro; Yoshikawa, Takeshi; Kadowaki, Shusaku; Okunishi, Suguru; Maeda, Hiroto

    2017-01-01

     A marine raphidophyte Heterosigma akashiwo is a causative agent of harmful microalgal blooms, which often cause the massive mortality of aquacultured finfish. In the present study, the Pacific oyster Crassostrea gigas was reared with H. akashiwo, and effect of the microalga on filter-feeding behavior and microflora of the gastrointestinal tract was investigated. The intake of the raphidophyte cells inhibited the molluscan filter-feeding activities, suggesting the negative physiological effect of the microalgal cell contents. However, the bivalves ingested the H. akashiwo cells to the same extent as the diatom Chaetoceros calcitrans, a non-harmful indicator to estimate the filtration rate, showing a continuation of their non-selective ingestion of the phytoplankton. Microflora of the oyster soft tissue was dominated by bacteria affiliated with the family Rhodobacteraceae, some of which are associated with microalgae. In addition, the Bacteroidetes species, in which algicidal bacteria are included, were also found in the bivalve individuals exposed to H. akashiwo. These results suggested that the ingested phytoplankton affected the microbial flora in the gastrointestinal tracts, some constituents of which helped the mollusc assimilate the ingested red tide phytoplankton. This study will provide beneficial information to clarify mechanisms by which the oyster evades the ichthyotoxicity of harmful microalgae and the participation of the intestinal microorganisms in these processes.

  7. Lethal effects of ichthyotoxic raphidophytes, Chattonella marina, C. antiqua, and Heterosigma akashiwo, on post-embryonic stages of the Japanese pearl oyster, Pinctada fucata martensii.

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    Basti, Leila; Nagai, Kiyohito; Go, Jiyoji; Okano, Sho; Oda, Tatsuya; Tanaka, Yuji; Nagai, Satoshi

    2016-11-01

    The inimical effects of the ichthyotoxic harmful algal bloom (HAB)-forming raphidophytes Heterosigma akashiwo, Chattonella marina, and Chattonella antiqua on the early-life stages of the Japanese pearl oyster Pinctada fucata martensii were studied. Fertilized eggs and developing embryos were not affected following exposure to the harmful raphidophytes; however, all three algal species severely affected trochophores and D-larvae, early-stage D-larvae, and late-stage pre-settling larvae. Exposure to C. marina (5×10 2 cellsml -1 ), C. antiqua (10 3 cellsml -1 ), and H. akashiwo (5×10 3 cellsml -1 ) resulted in decreased success of metamorphosis to the trochophore stage. A complete inhibition of trochophore metamorphosis was observed following exposure to C. antiqua at 5×10 3 cellsml -1 and C. marina at 8×10 3 cellsml -1 . In all experiments, more than 80% of newly formed trochophores were anomalous, and in the case of exposure to H. akashiwo at 10 5 cellsml -1 more than 70% of D-larvae were anomalous. The activity rates of D-larvae (1-day-old) were significantly reduced following exposure to C. antiqua (8×10 3 cellsml -1 , 24h), C. marina (8×10 3 cellsml -1 , 24h), and H. akashiwo (10 4 cellsml -1 , 24h). The activity rates of pre-settling larvae (21-day-old) were also significantly reduced following exposure to C. antiqua (10 3 cellsml -1 , 24h),C. marina (8×10 3 cellsml -1 , 24h), and H. akashiwo (5×10 4 cellsml -1 , 24h). Significant mortalities of both larval stages were induced by all three raphidophytes, with higher mortality rates registered for pre-settling larvae than D-larvae, especially following exposure to C. marina (5×10 2 -8×10 3 cellsml -1 , 48-86h) and C. antiqua (10 3 -8×10 3 cellsml -1 , 72-86h). Contact between raphidophyte cells and newly metamorphosed trochophores and D-larvae, 1-day-old D-larvae, and 21-day-old larvae resulted in microscopic changes in the raphidophytes, and then, in the motile early-life stages of pearl oysters. Upon

  8. Oceanographic and physiological parameters relating to Heterosigma akashiwo in Puget Sound - The Ecophysiology and Toxicity of Heterosigma akashiwo in Puget Sound: A Living Laboratory Ecosystem Approach

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    National Oceanic and Atmospheric Administration, Department of Commerce — Over one half of the worlds fish production for human consumption currently comes from aquaculture, while wild fisheries yields are either stable or declining....

  9. Heterosigma bloom and associated fish kill

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    Hershberger, P.K.; Rensel, J.E.; Postel, J.R.; Taub, F.B.

    1997-01-01

    A bloom of the harmful marine phytoplankton, Heterosigma carterae occurred in upper Case Inlet, south Puget Sound, Washington in late September, 1994, correlating with the presence of at least 35 dead salmon. This marks the first time that this alga has been closely correlated with a wild fish kill; in the past it was thought to be associated with kills of penned fish at fish farms only. We were informed of the presence of a possible harmful algal bloom and dead salinois Ilear the town of Allyn on 27 September and a team was formed to investigate. We arrived at the Allyn waterfront at 17:30 hours the same day. Prior to our arrival, state agency personnel walked approximatcly two miles of shoreline from the powerlines north of the dock, to the mouth of Sherwood Creek and conducted the only official count of dead fish present along the shore consisting of 12 coho salmon (Oncorhynchus kisutch), 11 chum salmon (Oncorhynchus keta), 12 chinook salmon (Oncorhynchus tschawytscha), one flat fish, and one sculpin on the morning of 9/27. Since previous harmful blooms of Heterosigma have resultedin the majority of net penreared salmon sinking to the bottom of pens, and only approximately two miles of shoreline were sampled, it is suspected that many more exposed fish may have succumbed than were counted. Witnesses who explored the east side of the bay reported seeing many dead salmon there as well, but no counts were made. State agency personnel who observed the fish kill reported seeing “dying fish coming to the beach, gulping at the surface, trying to get out of the water” Scavengers were seen consuming the salmon carcasses; these included two harbor seals, a house cat, and Hymenopteran insects. None suffered any noticeable acute ill effects. Although precise cause of death has not been ascertained, visual inspection of the reproductive organs from a deceased male chum salmon found on the shore at Allyn confirmed that the fish was not yet reproductively mature and

  10. Algicidal Effects of a Novel Marine Pseudoalteromonas Isolate (Class Proteobacteria, Gamma Subdivision) on Harmful Algal Bloom Species of the Genera Chattonella, Gymnodinium, and Heterosigma

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    Lovejoy, Connie; Bowman, John P.; Hallegraeff, Gustaaf M.

    1998-01-01

    During a bacterial survey of the Huon Estuary in southern Tasmania, Australia, we isolated a yellow-pigmented Pseudoalteromonas strain (class Proteobacteria, gamma subdivision), designated strain Y, that had potent algicidal effects on harmful algal bloom species. This organism was identified by 16S rRNA sequencing as a strain with close affinities to Pseudoalteromonas peptidysin. This bacterium caused rapid cell lysis and death (within 3 h) of gymnodinoids (including Gymnodinium catenatum) and raphidophytes (Chattonella marina and Heterosigma akashiwo). It caused ecdysis of armored dinoflagellates (e.g., Alexandrium catenella, Alexandrium minutum, and Prorocentrum mexicanum), but the algal cultures then recovered over the subsequent 24 h. Strain Y had no effect on a cryptomonad (Chroomonas sp.), a diatom (Skeletonema sp.), a cyanobacterium (Oscillatoria sp.), and two aplastidic protozoans. The algicidal principle of strain Y was excreted into the seawater medium and lost its efficacy after heating. Another common bacterial species, Pseudoalteromonas carrageenovora, was isolated at the same time and did not have these algicidal effects. The minimum concentrations of strain Y required to kill G. catenatum were higher than the mean concentrations found in nature under nonbloom conditions. However, the new bacterium showed a chemotactic, swarming behavior that resulted in localized high concentrations around target organisms. These observations imply that certain bacteria could play an important role in regulating the onset and development of harmful algal blooms. PMID:9687434

  11. The dinoflagellate Akashiwo sanguinea will benefit from future climate change: The interactive effects of ocean acidification, warming and high irradiance on photophysiology and hemolytic activity.

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    Ou, Guanyong; Wang, Hong; Si, Ranran; Guan, Wanchun

    2017-09-01

    Due to global climate change, marine phytoplankton will likely experience low pH (ocean acidification), high temperatures and high irradiance in the future. Here, this work report the results of a batch culture experiment conducted to study the interactive effects of elevated CO 2 , increased temperature and high irradiance on the harmful dinoflagellate Akashiwo sanguinea, isolated at Dongtou Island, Eastern China Sea. The A. sanguinea cells were acclimated in high CO 2 condition for about three months before testing the responses of cells to a full factorial matrix experimentation during a 7-day period. This study measured the variation in physiological parameters and hemolytic activity in 8 treatments, representing full factorial combinations of 2 levels each of exposure to CO 2 (400 and 1000μatm), temperature (20 and 28°C) and irradiance (50 and 200μmol photons m -2 s -1 ). Sustained growth of A. sanguinea occurred in all treatments, but high CO 2 (HC) stimulated faster growth than low CO 2 (LC). The pigments (chlorophyll a and carotenoid) decreased in all HC treatments. The quantum yield (F v /F m ) declined slightly in all high-temperature (HT) treatments. High irradiance (HL) induced the accumulation of ultraviolet-absorbing compounds (UV abc ) irrespective of temperature and CO 2 . The hemolytic activity in the LC treatments, however, declined when exposed to HT and HL, but HC alleviated the adverse effects of HT and HL on hemolytic activity. All HC and HL conditions and the combinations of high temperature*high light (HTHL) and high CO 2 *high temperature*high light (HCHTHL) positively affected the growth in comparison to the low CO 2 *low temperature*low light (LCLTLL) treatment. High temperature (HT), high light (HL) and a combination of HT*HL, however, negatively impacted hemolytic activity. CO 2 was the main factor that affected the growth and hemolytic activity. There were no significant interactive effects of CO 2 *temperature*irradiance on growth

  12. [Acute toxicity effects of three red tide algae on Brachionus plicatilis].

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    Zhou, Wen-Li; Xiao, Hui; Wang, You; Zhai, Hong-Chang; Tang, Xue-Xi

    2008-11-01

    Acute toxicity testing method was used to study effects of different density of Prorocentrum donghaiense, Heterosigma akashiwo and Alexandrium tamarense on mortality rates and population growth parameter of Brachionus plicatilis under controlled experimental conditions. Results showed that 24 h LC50 values of Prorocentrum donghaiense, Heterosigma akashiwo and Alexandrium tamarense treatment to mortality rate of Brachionus plicatilis were 3.56, 1.21 and 0.49 (x 10(4) cells/mL) respectively. Marked density effects were presented when three species of red tide microalga showed their toxicity to Brachionus plicatilis. There were significant inhibitory effects on Brachionus plicatilis when it was exposed to cells of Prorocentrum donghaiense at the concentration of 10(4) cells/mL, filtrate and cell contents of Heterosigma akashiwo at the concentration of 10(5) cells/mL, and cells, filtrate and cell contents of Alexandrium tamarense at the concentration of 10(3) cells/mL respectively. Inhibitory effects of three species of microalga on Brachionus plicatilis were enhanced with increasing of microalgal density.

  13. Concentrations of 210Po in fish and shellfish from southern region of Japan and evaluation of 210Po intake from seafood for Japanese people

    International Nuclear Information System (INIS)

    Momoshima, N.; Sugihara, S.; Nakao, H.

    2012-01-01

    Concentrations of 210 Po in fish and shellfish, mostly collected from southern region of Japan were analyzed. Values ranged from 0.2 to 229 Bq/kg fresh weight and higher concentrations were observed in samples analyzed with viscera. Intake of 210 Po through fish and shellfish was evaluated at different Japanese cities based on statistical consumption data. Phytoplankton, Heterosigma akashiwo was collected during a harmful algal bloom and 210 Po was analyzed. The phytoplankton occupied only 4.4% of 210 Po in seawater and a large fraction of 210 Po was observed in the particulate form. (orig.)

  14. Screening and isolation of the algicidal compounds from marine green alga Ulva intestinalis

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    Sun, Xue; Jin, Haoliang; Zhang, Lin; Hu, Wei; Li, Yahe; Xu, Nianjun

    2016-07-01

    Twenty species of seaweed were collected from the coast of Zhejiang, China, extracted with ethanol, and screened for algicidal activity against red tide microalgae Heterosigma akashiwo and Prorocentrum micans. Inhibitory effects of fresh and dried tißsues of green alga Ulva intestinalis were assessed and the main algicidal compounds were isolated, purified, and identified. Five seaweed species, U. intestinalis, U. fasciata, Grateloupia romosissima, Chondria crassicaulis, and Gracilariopsis lemaneiformis, were investigated for their algicidal activities. Fresh tissues of 8.0 and 16.0 mg/mL of U. intestinalis dissolved in media significantly inhibited growth of H. akashiwo and P. micans, respectively. Dried tissue and ethyl acetate (EtOAc) extracts of U. intestinalis at greater than 1.2 and 0.04 mg/mL, respectively, were fatal to H. akashiwo, while its water and EtOAc extracts in excess of 0.96 and 0.32 mg/mL, respectively, were lethal to P. micans. Three algicidal compounds in the EtOAc extracts were identified as 15-ethoxy-(6z,9z,12z)-hexadecatrienoic acid (I), (6E,9E,12E)-(2-acetoxy- β-D-glucose)-octadecatrienoic acid ester (II) and hexadecanoic acid (III). Of these, compound II displayed the most potent algicidal activity with IC50 values of 4.9 and 14.1 µg/mL for H. akashiwo and P. micans, respectively. Compound I showed moderate algicidal activity with IC50 values of 13.4 and 24.7 µg/mL for H. akashiwo and P. micans, respectively. These findings suggested that certain macroalgae or products therefrom could be used as effective biological control agents against red tide algae.

  15. Application of rotifer Brachionus plicatilis in detecting the toxicity of harmful algae

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    Yan, Tian; Wang, Yunfeng; Wang, Liping; Chen, Yang; Han, Gang; Zhou, Mingjiang

    2009-05-01

    The toxicity of seven major HAB (harmful algal bloom) species/strains, Prorocentrum donghaiense, Phaeocystis globosa, Prorocentrum micans, Alexandrium tamarense (AT-6, non-PSP producer), Alexandrium lusitanicum, Alexandrum tamarense (ATHK) and Heterosigma akashiwo were studied against rotifer Brachionus plicatilis under laboratory conditions. The results show that P. donghaiense, P. globosa, P. micans, A. tamarense (AT-6), or A. lusitanicum could maintain the individual survival and reproduction, as well as the population increase of the rotifer, but the individual reproduction would decrease when exposed to these five algae at higher densities for nine days; H. akashiwo could decrease the individual survival and reproduction, as well as population increase of the rotifer, which is similar to that of the starvation group, indicating that starvation might be its one lethal factor except for the algal toxins; A. tamarense (ATHK) has strong lethal effect on the rotifer with 48h LC50 at 800 cells/mL. The experiment on ingestion ability indicated by gut pigment change shows that P. donghaiense, P. globosa, P. micans, A. tamarense (AT-6) and A. lusitanicum can be taken by the rotifers as food, but A. tamarense (ATHK) or H. akashiwo can be ingested by the rotifers. The results indicate that all the indexes of individual survival and reproduction, population increase, gut pigment change of the rotifers are good and convenient to be used to reflect the toxicities of HAB species. Therefore, rotifer is suggested as one of the toxicity testing organisms in detecting the toxicity of harmful algae.

  16. Allelopathic effect of Chattonella marina var. marina (Raphidophyceae) on Gymnodinium catenatum (Dinophycea).

    Science.gov (United States)

    Fernández-Herrera, Leyberth J; Band-Schmidt, Christine J; López-Cortés, David J; Hernández-Guerrero, Claudia J; Bustillos-Guzmán, José J; Núñez-Vázquez, Erick

    2016-01-01

    The allelopathic effect of the raphidophyte Chattonella marina var. marina on the dinoflagellate Gymnodinium catenatum was determined. Both species are harmful algal bloom forming algae, produce toxic metabolites, and can co-exist in the environment. In general, raphidophytes tend to dominate over dinoflagellates, which may indicate an allelopathic effect of the former algae. Strains of C. marina var. marina and G. catenatum isolated from Bahía de La Paz were cultured in bi-algal cultures with and without cell contact. Additionally, cultures of G. catenatum were exposed to cell-free culture filtrates of the raphidophyte to test whether soluble allelopathic molecules are active. During late stationary phase, both species were cultivated in mixed cultures for 72h using the following cell abundance proportions: 20×10 3 cellsL -1 : 20×10 3 cellsL -1 (1:1; G. catenatum: C. marina); 10×10 3 cellsL -1 : 20×10 3 cellsL -1 (1:2), and 20×10 3 cellsL -1 : 10×10 3 cellsL -1 (2:1). Cells of G. catenatum were also exposed to different volumes of cell filtrates of C. marina (10, 20, and 50mL) using the same cell abundance proportions for 24h. Samples were taken daily for cell counts and microscopic observations. Growth inhibition was higher when there was cell contact between both species, however mortality of G. catenatum was also observed without direct cell contact, indicating that toxic metabolites are liberated to the culture medium. Changes in cell morphology of G. catenatum occurred in the presence of cells and filtrates of C. marina, such as loss of flagella and motility, swelling, loss of girdle and sulci, prominent nucleus, rupture of cell membrane, and cell lysis. Induction of temporary cysts was also observed. These results suggest that toxic metabolites are liberated to the medium by C. marina, affecting G. catenatum by inhibiting its growth and causing changes in its life history, providing new insights of interactions between raphidophytes and dinoflagellates that could happen in the natural environment when both species are present. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. CHATTONELLA MARINA (RAPHIDOPHYCEAE), A POTENTIALLY TOXIC ALGA IN THE SALTON SEA, CALIFORNIA. (R826552)

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    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...

  18. Specific toxic effect of dinoflagellate Heterocapsa circularisquama on the rotifer Brachionus plicatilis.

    Science.gov (United States)

    Kim, D; Sato, Y; Oda, T; Muramatsu, T; Matsuyama, Y; Honjo, T

    2000-12-01

    Heterocapsa circularisquama (Dinophyceae), a noxious red tide dinoflagellate, is known to have a specifically lethal effect on shellfish, especially bivalves such as pearl oyster (Pinctada fucata), but no detrimental effects of this alga on fishes have not been observed so far. In this study, we found that H. circularisquama was toxic to a microzooplankton, a rotifer (Brachionus plicatilis) in a cell concentration-dependent manner, while the cultured supernatant or ultrasonic ruptured H. circularisquama had no significant toxic effect on the rotifer. Since no such toxic effects on the rotifer were observed in Chattonella marina, Heterosigma akashiwo, or Cochlodinium polykrikoides, other species of harmful red tide plankton, H. circularisquama may have a strictly specific toxic mechanism against the rotifer as well as bivalves.

  19. Responding to flow: How phytoplankton adapt migration strategies to tackle turbulence

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    Sengupta, Anupam; Carrara, Francesco; Stocker, Roman

    2014-11-01

    Phytoplankton are among the ocean's most important organisms and it has long been recognized that turbulence is a primary determinant of their fitness. Yet, mechanisms by which phytoplankton may adapt to turbulence have remained unknown. We present experiments that demonstrate how phytoplankton are capable of rapid adaptive behavior in response to fluid flow disturbances that mimic turbulence. Our study organism was the toxic marine alga Heterosigma akashiwo, known to exhibit ``negative gravitaxis,'' i . e . , to frequently migrate upwards against gravity. To mimic the effect of Kolmogorov-scale turbulent eddies, which expose cells to repeated reorientations, we observed H. akashiwo in a ``flip chamber,'' whose orientation was periodically flipped. Tracking of single cells revealed a striking, robust behavioral adaptation, whereby within tens of minutes half of the population reversed its direction of migration to swim downwards, demonstrating an active response to fluid flow. Using confocal microscopy, we provide a physiological rationalization of this behavior in terms of the redistribution of internal organelles, and speculate on the motives for this bet-hedging-type strategy. This work suggests that the effects of fluid flow - not just passive but also active - on plankton represents a rich area of investigation with considerable implications for some of earth's most important organisms.

  20. A turbulence-induced switch in phytoplankton swimming behavior

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    Carrara, Francesco; Sengupta, Anupam; Stocker, Roman

    2015-11-01

    Phytoplankton, unicellular photosynthetic organisms that form the basis of life in aquatic environments, are frequently exposed to turbulence, which has long been known to affect phytoplankton fitness and species succession. Yet, mechanisms by which phytoplankton may adapt to turbulence have remained unknown. Here we present a striking behavioral response of a motile species - the red-tide-producing raphidophyte Heterosigma akashiwo - to hydrodynamic cues mimicking those experienced in ocean turbulence. In the absence of turbulence, H. akashiwo exhibits preferential upwards swimming (`negative gravitaxis'), observable as a strong accumulation of cells at the top of an experimental container. When cells were exposed to overturning in an automated chamber - representing a minimum experimental model of rotation by Kolmogorov-scale turbulent eddies - the population robustly split in two nearly equi-abundant subpopulations, one swimming upward and one swimming downward. Microscopic observations at the single-cell level showed that the behavioral switch was accompanied by a rapid morphological change. A mechanistic model that takes into account cell shape confirms that modulation of morphology can alter the hydrodynamic stress distribution over the cell body, which, in turn, triggers the observed switch in phytoplankton migration direction. This active response to fluid flow, whereby microscale morphological changes influence ocean-scale migration dynamics, could be part of a bet-hedging strategy to maximize the chances of at least a fraction of the population evading high-turbulence microzones.

  1. Experimental study on the interspecific interactions between the two bloom-forming algal species and the rotifer Brachionus plicatilis

    Science.gov (United States)

    Xie, Zhihao; Xiao, Hui; Tang, Xuexi; Cai, Hengjiang

    2009-06-01

    The interspecific interactions between the rotifer Brachionus plicatilis and two harmful algal blooms (HAB) species were investigated experimentally by single culture method. B. plicatilis population and the growth of the two algae were compared at different algal cell densities. The results demonstrated that the B. plicatilis obtained sufficient nutrition from Prorocentrum donghaiense to support net population increase. With exposure to 2.5×104 cells mL-1 of P. donghaiense, the number of B. plicatilis increased faster than it did when exposed to other four algal densities (5, 10, 15 and 20 ×104 cells mL-1), and the increase rate of B. plicatilis population ( r) at this algal density was 0.104 ± 0.015 rd-1. Cell densities of P. donghaiense decreased due to the grazing of B. plicatilis. In contrast, Heterosigma akashiwo had an adverse effect on B. plicatilis population and its growth was largely unaffected by rotifer grazing. In this case, B. plicatilis population decreased and H. akashiwo grew at a rate similar to that of the control.

  2. Exceptional colored in the Lebanese coastal water of the area Zouk - Nahr el Kelb in spring 2007

    International Nuclear Information System (INIS)

    Abboud Abi Saab, M.; Fakhri, M.; Kassab, M.-T.; Matar, N.

    2008-01-01

    A brownish coloring in the Lebanese coastal water of the area Zouk - Nahr el Kelb area was detected in May 2007. The qualitative and quantitative analyses, in comparison with preceding data, showed that this phenomenon was due mainly to the massive and exceptional bloom of both a centric diatom Skeletonema costatum (Greville) Cleve reaching 1,6 x 107L-1 cells and of an ichtyotoxic raphidophyte Heterosigma akashiwo (Hada) Hada reaching approximately 9 x 106L-1cells. The maximum of this proliferation was located in surface water opposite Zouk power plant where the measured rates of chl-a reached 32 mg.m-3indicating a phenomenon of eutrophication. Attempts were made at explaining the mechanism of development of this algal bloom. The hydro-climatic conditions prevailing during a heat wave coupled with nutrient availability are probably the cause to the development of this phenomenon. The fact that the benthic cystsproduced by the cells of H. akashiwo may develop each year when the conditions of the environment become favorable thus causing a risk of the widening of this phenomenon. (author)

  3. Occurrence of four species of algae in the marine water of Hong Kong.

    Science.gov (United States)

    Chai, Yemao; Deng, Wen-Jing; Qin, Xing; Xu, Xiangrong

    2017-11-30

    Harmful algal blooms (HABs) have broken out frequently throughout the world in recent decades; they are caused by the rapid multiplication of algal cells in near-coastal waters polluted with nitrogen and phosphorus and greatly affect the quality of marine water and human health. Over the past several decades, climate change and increasing environmental degradation have provided favourable growth conditions for certain phytoplankton species. Therefore, it is essential to rapidly identify and enumerate harmful marine algae to control these species. In this study, quantitative PCR (qPCR) was used to detect four representative species of HABs that are widespread in the marine water of Hong Kong, namely, Alexandrium catenella, Pseudo-nitzschia spp., Karenia mikimotoi and Heterosigma akashiwo. We applied qPCR with the dye SYBR Green to detect Alexandrium spp. and Pseudo-nitzschia spp. and used TaqMan probe for the enumeration of Karenia mikimotoi and Heterosigma akashiwo. The total genomic DNA of these algae from Hong Kong marine water was extracted successfully using the CTAB method, and for each kind of alga, we constructed a ten-fold series of recombinant plasmid solutions containing certain gene fragments of 18S rDNA and ITS1-5.8S-ITS2 as standard samples. Ten-fold dilutions of the DNA of known numbers of the extracted algal cells were also used to create an additional standard curve. In this way, the relationship between the cell number and the related plasmid copy number was established. The qPCR assay displayed high sensitivity in monitoring marine water samples in which the low concentrations of harmful algae were not detected accurately by traditional methods. The results showed that the cell numbers of the four species were all in low abundance. For Alexandrium catenella, the cell abundances at 12 sites ranged from 3.8×10 2 to 4.3×10 3 cellsL -1 , while H. akashiwo, K. mikimotoi and Pseudo-nitzschia ranged from 1.1×10 2 to 1.3×10 3 , from 23 to 6.5×10 2

  4. Selective algicidal action of peptides against harmful algal bloom species.

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    Seong-Cheol Park

    Full Text Available Recently, harmful algal bloom (HAB, also termed "red tide", has been recognized as a serious problem in marine environments according to climate changes worldwide. Many novel materials or methods to prevent HAB have not yet been employed except for clay dispersion, in which can the resulting sedimentation on the seafloor can also cause alteration in marine ecology or secondary environmental pollution. In the current study, we investigated that antimicrobial peptide have a potential in controlling HAB without cytotoxicity to harmless marine organisms. Here, antimicrobial peptides are proposed as new algicidal compounds in combating HAB cells. HPA3 and HPA3NT3 peptides which exert potent antimicrobial activity via pore forming action in plasma membrane showed that HPA3NT3 reduced the motility of algal cells, disrupted their plasma membrane, and induced the efflux of intracellular components. Against raphidoflagellate such as Heterosigma akashiwo, Chattonella sp., and C. marina, it displayed a rapid lysing action in cell membranes at 1~4 µM within 2 min. Comparatively, its lysing effects occurred at 8 µM within 1 h in dinoflagellate such as Cochlodium polykrikoides, Prorocentrum micans, and P. minimum. Moreover, its lysing action induced the lysis of chloroplasts and loss of chlorophyll a. In the contrary, this peptide was not effective against Skeletonema costatum, harmless algal cell, even at 256 µM, moreover, it killed only H. akashiwo or C. marina in co-cultivation with S. costatum, indicating to its selective algicidal activity between harmful and harmless algal cells. The peptide was non-hemolytic against red blood cells of Sebastes schlegeli, the black rockfish, at 120 µM. HAB cells were quickly and selectively lysed following treatment of antimicrobial peptides without cytotoxicity to harmless marine organisms. Thus, the antibiotic peptides examined in our study appear to have much potential in effectively controlling HAB with minimal

  5. Characterizing seston in the Penobscot River Estuary.

    Science.gov (United States)

    Meseck, Shannon L; Li, Yaqin; Sunila, Inke; Dixon, Mark; Clark, Paul; Lipsky, Christine; Stevens, Justin R; Music, Paul; Wikfors, Gary H

    2017-10-01

    The Penobscot River Estuary is an important system for diadromous fish in the Northeast United States of American (USA), in part because it is home to the largest remnant population of Atlantic salmon, Salmo salar, in the country. Little is known about the chemical and biological characteristics of seston in the Penobscot River Estuary. This study used estuarine transects to characterize the seston during the spring when river discharge is high and diadromous fish migration peaks in the Penobscot River Estuary. To characterize the seston, samples were taken in spring 2015 for phytoplankton identification, total suspended matter (TSM), percent organic TSM, chlorophyll a, particle size (2 μm-180 μm), particulate carbon and nitrogen concentrations, and stable carbon and nitrogen isotopes. The estuarine profiles indicate that TSM behaved non-conservatively with a net gain in the estuary. As phytoplankton constituted only 1/1000 of the particles, the non-conservative behavior of TSM observed in the estuary was most likely not attributable to phytoplankton. Particulate carbon and nitrogen ratios and stable isotope signals indicate a strong terrestrial, allochthonous signal. The seston in the Penobscot River Estuary was dominated by non-detrital particles. During a short, two-week time period, Heterosigma akashiwo, a phytoplankton species toxic to finfish, also was detected in the estuary. A limited number of fish samples, taken after the 2015 Penobscot River Estuary bloom of H. akashiwo, indicated frequent pathological gill damage. The composition of seston, along with ichthyotoxic algae, suggest the need for further research into possible effects upon resident and migratory fish in the Penobscot River Estuary. Published by Elsevier Ltd.

  6. Phytoplankton can actively diversify their migration strategy in response to turbulent cues.

    Science.gov (United States)

    Sengupta, Anupam; Carrara, Francesco; Stocker, Roman

    2017-03-23

    Marine phytoplankton inhabit a dynamic environment where turbulence, together with nutrient and light availability, shapes species fitness, succession and selection. Many species of phytoplankton are motile and undertake diel vertical migrations to gain access to nutrient-rich deeper layers at night and well-lit surface waters during the day. Disruption of this migratory strategy by turbulence is considered to be an important cause of the succession between motile and non-motile species when conditions turn turbulent. However, this classical view neglects the possibility that motile species may actively respond to turbulent cues to avoid layers of strong turbulence. Here we report that phytoplankton, including raphidophytes and dinoflagellates, can actively diversify their migratory strategy in response to hydrodynamic cues characteristic of overturning by Kolmogorov-scale eddies. Upon experiencing repeated overturning with timescales and statistics representative of ocean turbulence, an upward-swimming population rapidly (5-60 min) splits into two subpopulations, one swimming upward and one swimming downward. Quantitative morphological analysis of the harmful-algal-bloom-forming raphidophyte Heterosigma akashiwo together with a model of cell mechanics revealed that this behaviour was accompanied by a modulation of the cells' fore-aft asymmetry. The minute magnitude of the required modulation, sufficient to invert the preferential swimming direction of the cells, highlights the advanced level of control that phytoplankton can exert on their migratory behaviour. Together with observations of enhanced cellular stress after overturning and the typically deleterious effects of strong turbulence on motile phytoplankton, these results point to an active adaptation of H. akashiwo to increase the chance of evading turbulent layers by diversifying the direction of migration within the population, in a manner suggestive of evolutionary bet-hedging. This migratory behaviour

  7. Progress in Understanding Algal Bloom-Mediated Fish Kills: The Role of Superoxide Radicals, Phycotoxins and Fatty Acids.

    Directory of Open Access Journals (Sweden)

    Juan José Dorantes-Aranda

    Full Text Available Quantification of the role of reactive oxygen species, phycotoxins and fatty acids in fish toxicity by harmful marine microalgae remains inconclusive. An in vitro fish gill (from rainbow trout Oncorhynchus mykiss assay was used to simultaneously assess the effect in superoxide dismutase, catalase and lactate dehydrogenase enzymatic activities caused by seven species of ichthyotoxic microalgae (Chattonella marina, Fibrocapsa japonica, Heterosigma akashiwo, Karenia mikimotoi, Alexandrium catenella, Karlodinium veneficum, Prymnesium parvum. Quantification of superoxide production by these algae was also performed. The effect of purified phycotoxins and crude extracts was compared, and the effect of fatty acids is discussed. The raphidophyte Chattonella was the most ichthyotoxic (gill cell viability down to 35% and also the major producer of superoxide radicals (14 pmol cell-1 hr-1 especially after cell lysis. The raphidophyte Heterosigma and dinoflagellate Alexandrium were the least toxic and had low superoxide production, except when A. catenella was lysed (5.6 pmol cell-1 hr-1. Catalase showed no changes in activity in all the treatments. Superoxide dismutase (SOD and lactate dehydrogenase exhibited significant activity increases of ≤23% and 51.2% TCC (total cellular content, respectively, after exposure to C. marina, but SOD showed insignificant changes with remaining algal species. A strong relationship between gill cell viability and superoxide production or superoxide dismutase was not observed. Purified brevetoxins PbTx-2 and -3 (from Karenia brevis, LC50 of 22.1 versus 35.2 μg mL-1 and karlotoxin KmTx-2 (from Karlodinium; LC50 = 380 ng mL-1 could almost entirely account for the fish killing activity by those two dinoflagellates. However, the paralytic shellfish toxins (PST GTX1&4, C1&C2, and STX did not account for Alexandrium ichthyotoxicity. Only aqueous extracts of Alexandrium were cytotoxic (≤65% decrease of viability, whereas

  8. Effectiveness of an anti-algal compound in eliminating an aquatic unicellular harmful algal Phaeocystis globosa

    Directory of Open Access Journals (Sweden)

    Huajun eZhang

    2016-04-01

    Full Text Available Phaeocystis globosa blooms can have negative effects on higher trophic levels in the marine ecosystem and consequently influence human activities. Strain KA22, identified as the bacterium Hahella, was isolated from coastal surface water and used to control P. globosa growth. A methanol extract from the bacteral cells showed strong algicidal activity. After purification, the compound showed a similar structure to prodigiosin when identified with Q-Exactive Orbitrap MS and nuclear magnetic resonance spectra. The compound showed algicidal activity against P. globosa with a 50% Lethal Dose (LD50 of 2.24 μg/mL. The prodigiosin was stable under heat and acid environment, and it could be degraded under alkaline environment and natural light condition. The growth rates of strain KA22 was fast in 2216E medium and the content of prodigiosin in this medium was more than 70 μg/mL after 16 h incubation. The compound showed particularly strong algicidal activity against Prorocentrum donghaiense, P. globosa and Heterosigma akashiwo, but having little effect on three other phytoplankton species tested. The results of our research could increase our knowledge on harmful algal bloom control compound and lead to further study on the mechanisms of the lysis effect on harmful algae.

  9. Harmful algae and toxis in paranaguá bay , Brazil: bases for monitoring

    Directory of Open Access Journals (Sweden)

    Luiz Laureno Mafra Junior

    2006-09-01

    Full Text Available The estuarine complex of Paranaguá - ECP (South Brazil, 25º30'S, 48º30'W is a large subtropical system, where pristine mangrove forests are still present, and fishery and aquaculture are important economic activities. This work investigated the occurrence of harmful algae in Paranaguá Bay, as well as the presence of toxins in the filter feeding mussel Mytella guyanensis, a local fishery resource. Samples along the Paranaguá sub-system were collected almost monthly from August 2002 to October 2003. Besides physical and chemical variables, cell densities of harmful species and presence of toxins in the mussel by mouse bioassay (DSP, PSP and HPLC (ASP were performed. HAB species included Pseudo-nitzschia spp., Dinophysis acuminata,Prorocentrum minimum,Gymnodinium catenatum,Phaeocystis spp., Chattonella spp. and Heterosigma akashiwo.Trichodesmium erythraeum and Coscinodiscus wailesii were also included in this study due to their potential for harmful bloom formation. Toxin results showed the occurrence of DSP (December 2002 in shellfish related to the presence of D. acuminata (max. 4,566 cells.l-1. Additionally, cultivated strains produced paralytic and amnesic toxins in laboratory. Spring (October to December, Southern Hemisphere and late summer (February to April were the periods of higher abundance of harmful algae, mainly in euhaline and inner polyhaline sectors of the ECP.O complexo estuarino de Paranaguá (CEP; 25º30'S, 48º30'W, localizado no litoral sul do Brasil, abriga extensas áreas preservadas de manguezais e tem a pesca e aqüicultura como importantes atividades econômicas. Este trabalho investigou a ocorrência de microalgas nocivas no CEP e a presença de ficotoxinas no molusco bivalve Mytella guyanensis. Para tanto, foram coletadas amostras com periodicidade aproximadamente mensal, entre agosto de 2002 e outubro de 2003. Foram avaliadas variáveis físico-químicas, densidade de espécies nocivas e a presença de toxinas nos

  10. Phytoplankton calcification as an effective mechanism to alleviate cellular calcium poisoning

    Science.gov (United States)

    Müller, M. N.; Ramos, J. Barcelos e.; Schulz, K. G.; Riebesell, U.; Kaźmierczak, J.; Gallo, F.; Mackinder, L.; Li, Y.; Nesterenko, P. N.; Trull, T. W.; Hallegraeff, G. M.

    2015-11-01

    Marine phytoplankton have developed the remarkable ability to tightly regulate the concentration of free calcium ions in the intracellular cytosol at a level of ~ 0.1 μmol L-1 in the presence of seawater Ca2+ concentrations of 10 mmol L-1. The low cytosolic calcium ion concentration is of utmost importance for proper cell signalling function. While the regulatory mechanisms responsible for the tight control of intracellular Ca2+ concentration are not completely understood, phytoplankton taxonomic groups appear to have evolved different strategies, which may affect their ability to cope with changes in seawater Ca2+ concentrations in their environment on geological timescales. For example, the Cretaceous (145 to 66 Ma), an era known for the high abundance of coccolithophores and the production of enormous calcium carbonate deposits, exhibited seawater calcium concentrations up to 4 times present-day levels. We show that calcifying coccolithophore species (Emiliania huxleyi, Gephyrocapsa oceanica and Coccolithus braarudii) are able to maintain their relative fitness (in terms of growth rate and photosynthesis) at simulated Cretaceous seawater calcium concentrations, whereas these rates are severely reduced under these conditions in some non-calcareous phytoplankton species (Chaetoceros sp., Ceratoneis closterium and Heterosigma akashiwo). Most notably, this also applies to a non-calcifying strain of E. huxleyi which displays a calcium sensitivity similar to the non-calcareous species. We hypothesize that the process of calcification in coccolithophores provides an efficient mechanism to alleviate cellular calcium poisoning and thereby offered a potential key evolutionary advantage, responsible for the proliferation of coccolithophores during times of high seawater calcium concentrations. The exact function of calcification and the reason behind the highly ornate physical structures of coccoliths remain elusive.

  11. Differential Growth Responses of Marine Phytoplankton to Herbicide Glyphosate.

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    Cong Wang

    Full Text Available Glyphosate is a globally popular herbicide to kill weeds and its wide applications may lead to accumulation in coastal oceans as a source of phosphorus (P nutrient or growth inhibitor of phytoplankton. We studied the physiological effects of glyphosate on fourteen species representing five major coastal phytoplankton phyla (haptophyta, bacillariophyta, dinoflagellata, raphidophyta, and chlorophyta. Based on growth responses to different concentrations of glyphosate under contrasting dissolved inorganic phosphorus (DIP conditions, we found that phytoplankton species could be classified into five groups. Group I (Emiliania huxleyi, Skeletonema costatum, Phaeodactylum tricornutum could utilize glyphosate as sole P-source to support growth in axenic culture, but in the presence of DIP, they were inhibited by both 36-μM and 360-μM glyphosate. Group II (Karenia mikimotoi, Prorocentrum minimum, Dunaliella tertiolecta, Symbiodinium sp., Heterosigma akashiwo and Alexandrium catenella could not utilize glyphosate as sole P-source to support growth, and in the presence of DIP growth was not affected by 36-μM but inhibited by 360-μM glyphosate. Glyphosate consistently enhanced growth of Group III (Isochrysis galbana and inhibited Group IV (Thalassiosira weissflogii, Thalassiosira pseudonana and Chattonella marina regardless of DIP condition. Group V (Amphidinium carterae exhibited no measurable response to glyphosate regardless of DIP condition. This grouping is not congruent with the phylogenetic relationships of the phytoplankton species suggesting functional differentiation driven by environmental pressure. We conclude that glyphosate could be used as P-source by some species while is toxic to some other species and yet has no effects on others. The observed differential effects suggest that the continued use of glyphosate and increasing concentration of this herbicide in the coastal waters will likely exert significant impact on coastal marine

  12. Differential Growth Responses of Marine Phytoplankton to Herbicide Glyphosate

    Science.gov (United States)

    Wang, Cong; Lin, Xin; Li, Ling; Lin, Senjie

    2016-01-01

    Glyphosate is a globally popular herbicide to kill weeds and its wide applications may lead to accumulation in coastal oceans as a source of phosphorus (P) nutrient or growth inhibitor of phytoplankton. We studied the physiological effects of glyphosate on fourteen species representing five major coastal phytoplankton phyla (haptophyta, bacillariophyta, dinoflagellata, raphidophyta, and chlorophyta). Based on growth responses to different concentrations of glyphosate under contrasting dissolved inorganic phosphorus (DIP) conditions, we found that phytoplankton species could be classified into five groups. Group I (Emiliania huxleyi, Skeletonema costatum, Phaeodactylum tricornutum) could utilize glyphosate as sole P-source to support growth in axenic culture, but in the presence of DIP, they were inhibited by both 36-μM and 360-μM glyphosate. Group II (Karenia mikimotoi, Prorocentrum minimum, Dunaliella tertiolecta, Symbiodinium sp., Heterosigma akashiwo and Alexandrium catenella) could not utilize glyphosate as sole P-source to support growth, and in the presence of DIP growth was not affected by 36-μM but inhibited by 360-μM glyphosate. Glyphosate consistently enhanced growth of Group III (Isochrysis galbana) and inhibited Group IV (Thalassiosira weissflogii, Thalassiosira pseudonana and Chattonella marina) regardless of DIP condition. Group V (Amphidinium carterae) exhibited no measurable response to glyphosate regardless of DIP condition. This grouping is not congruent with the phylogenetic relationships of the phytoplankton species suggesting functional differentiation driven by environmental pressure. We conclude that glyphosate could be used as P-source by some species while is toxic to some other species and yet has no effects on others. The observed differential effects suggest that the continued use of glyphosate and increasing concentration of this herbicide in the coastal waters will likely exert significant impact on coastal marine phytoplankton

  13. Phytoplankton calcification as an effective mechanism to prevent cellular calcium poisoning

    Science.gov (United States)

    Müller, M. N.; Ramos, J. Barcelos e.; Schulz, K. G.; Riebesell, U.; Kaźmierczak, J.; Gallo, F.; Mackinder, L.; Li, Y.; Nesterenko, P. N.; Trull, T. W.; Hallegraeff, G. M.

    2015-08-01

    Marine phytoplankton has developed the remarkable ability to tightly regulate the concentration of free calcium ions in the intracellular cytosol at a level of ~ 0.1 μmol L-1 in the presence of seawater Ca2+ concentrations of 10 mmol L-1. The low cytosolic calcium ion concentration is of utmost importance for proper cell signalling function. While the regulatory mechanisms responsible for the tight control of intracellular Ca2+ concentration are not completely understood, phytoplankton taxonomic groups appear to have evolved different strategies, which may affect their ability to cope with changes in seawater Ca2+ concentrations in their environment on geological time scales. For example, the Cretaceous (145 to 66 Ma ago), an era known for the high abundance of coccolithophores and the production of enormous calcium carbonate deposits, exhibited seawater calcium concentrations up to four times present-day levels. We show that calcifying coccolithophore species (Emiliania huxleyi, Gephyrocapsa oceanica and Coccolithus braarudii) are able to maintain their relative fitness (in terms of growth rate and photosynthesis) at simulated Cretaceous seawater calcium concentrations, whereas these rates are severely reduced under these conditions in some non-calcareous phytoplankton species (Chaetoceros sp., Ceratoneis closterium and Heterosigma akashiwo). Most notably, this also applies to a non-calcifying strain of E. huxleyi which displays a calcium-sensitivity similar to the non-calcareous species. We hypothesize that the process of calcification in coccolithophores provides an efficient mechanism to prevent cellular calcium poisoning and thereby offered a potential key evolutionary advantage, responsible for the proliferation of coccolithophores during times of high seawater calcium concentrations.

  14. Harmful algal blooms (HABs), dissolved organic matter (DOM), and planktonic microbial community dynamics at a near-shore and a harbour station influenced by upwelling (SW Iberian Peninsula)

    Science.gov (United States)

    Loureiro, Sofia; Reñé, Albert; Garcés, Esther; Camp, Jordi; Vaqué, Dolors

    2011-05-01

    The surface microalgal community, including harmful species, dissolved organic matter (DOM), and bacterial and viral populations were studied during an annual cycle (November 2007-October 2008) in a Near-shore (NS) and a Harbour (H) station located in an upwelling area (Sagres, SW Iberian Peninsula). The higher water residence time, water stability and shallowness of harbours in comparison with open waters likely contributed to the differences found between stations regarding chemical variables, statistical correlations and harmful algal proliferations. Also, several differences were noticed from a previous assessment ( Loureiro et al., 2005) including higher SST, lower nitrate and chlorophyll a concentrations, along with a shift in the microplankton community structure from diatom to nanoflagellate predominance. These variations feasibly reflect the response of this dynamic system to regional environmental modifications contributing to the understanding of common patterns in environmental change trends. The division of the sampling period into (1) non-upwelling (Non-Uw), (2) "spin-up" of upwelling (SU-Uw), and (3) "spin-down" and relaxation-downwelling (SD-Rel) stages allowed the identification of natural groupings of microplankton samples by Multi Dimensional Scaling (MDS) analysis. Dissolved organic nitrogen (DON) and viruses were the most significant abiotic and biotic variables, respectively, contributing to the dissimilarities between these stages (SIMPER analysis) and, therefore, potentially affecting the microplankton community structure. Harmful algal species and a stable viral community appeared to be favoured by SD-Rel conditions. Data seem to indicate that both Gymnodinium catenatum and Heterosigma akashiwo, the most abundant potentially harmful species, have been imported into the sampling area. Also, the H location, together with potential retention sites developing around the Cabo de São Vicente upwelling centre, may contribute to the local

  15. Dynamics of motile phytoplankton in turbulence: Laboratory investigation of microscale patchiness

    Science.gov (United States)

    Crimaldi, J. P.; True, A.; Stocker, R.

    2016-02-01

    Phytoplankton represent the basis of oceanic life and play a critical role in biogeochemical cycles. While phytoplankton are traditionally studied in bulk, their collective impact stems from cell-level processes and interactions at the microscale. A fundamental element that determines these interactions is the small-scale spatial distribution of individual cells: this directly determines the local cell concentration and the probability that two cells contact or interact with each other. The traditional, bulk perspective on phytoplankton distributions is that turbulence acts to smear out patchiness and locally homogenizes the distributions. However, recent numerical simulations suggest that the action of turbulence on motile phytoplankton may be precisely the opposite: by biasing the swimming direction of cells through the action of viscous torques, turbulence is predicted to generate strong patchiness at small scales. Flow-mediated patch formation has been demonstrated experimentally in simple laminar flows, but has never been tested experimentally in turbulence. In this talk we report on preliminary laboratory experiments performed in a purpose-built flow facility that uses a pair of computer-controlled oscillating grids to generate approximately homogenous isotropic 3D turbulence. Turbulent flow characteristics and dissipation rates are first quantified using particle image velocimetry (PIV). Then, 2D distributions of the motile dinoflagellate Heterosigma akashiwo are imaged using planar laser-induced fluorescence (PLIF). Analysis of imaged phytoplankton distributions for patchiness is performed using a Voronoi tessellation approach. Results suggest that motile phytoplankton distributions differ from those of passive particles. Furthermore, computed values for the patch enhancement factor are shown to be roughly consistent with those of previous DNS predictions.

  16. The complete plastid genomes of the two 'dinotoms' Durinskia baltica and Kryptoperidinium foliaceum.

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    Behzad Imanian

    2010-05-01

    Full Text Available In one small group of dinoflagellates, photosynthesis is carried out by a tertiary endosymbiont derived from a diatom, giving rise to a complex cell that we collectively refer to as a 'dinotom'. The endosymbiont is separated from its host by a single membrane and retains plastids, mitochondria, a large nucleus, and many other eukaryotic organelles and structures, a level of complexity suggesting an early stage of integration. Although the evolution of these endosymbionts has attracted considerable interest, the plastid genome has not been examined in detail, and indeed no tertiary plastid genome has yet been sequenced.Here we describe the complete plastid genomes of two closely related dinotoms, Durinskia baltica and Kryptoperidinium foliaceum. The D. baltica (116470 bp and K. foliaceum (140426 bp plastid genomes map as circular molecules featuring two large inverted repeats that separate distinct single copy regions. The organization and gene content of the D. baltica plastid closely resemble those of the pennate diatom Phaeodactylum tricornutum. The K. foliaceum plastid genome is much larger, has undergone more reorganization, and encodes a putative tyrosine recombinase (tyrC also found in the plastid genome of the heterokont Heterosigma akashiwo, and two putative serine recombinases (serC1 and serC2 homologous to recombinases encoded by plasmids pCf1 and pCf2 in another pennate diatom, Cylindrotheca fusiformis. The K. foliaceum plastid genome also contains an additional copy of serC1, two degenerate copies of another plasmid-encoded ORF, and two non-coding regions whose sequences closely resemble portions of the pCf1 and pCf2 plasmids.These results suggest that while the plastid genomes of two dinotoms share very similar gene content and genome organization with that of the free-living pennate diatom P. tricornutum, the K. folicaeum plastid genome has absorbed two exogenous plasmids. Whether this took place before or after the tertiary

  17. Diel responses of phytoplankton of an Amazon floodplain lake at the two main hydrological phases

    Directory of Open Access Journals (Sweden)

    Kathrin Nere Passarinho

    2013-12-01

    Full Text Available AIM: This study examines the short-term changes of phytoplankton in an oxbow lake on the floodplain of the Acre River, Amazonia, Brazil. METHODS: Samples were taken with a Van Dorn bottle, at three depths (surface, middle and bottom, in two periods (low waters and high waters, for seven consecutive days in two schedules, night and morning. RESULTS: Phytoplankton was represented by 198 taxa and the Class Euglenophyceae, with 62 taxa, was the best-represented group in both periods. There were abrupt changes in the community during the high waters (potamophase. During this period, in conditions of partial atelomixis, we recorded higher values of phytoplankton biovolume and dominance of Gonyostomum semen (Ehr. Dies. (Raphidophyceae. CONCLUSIONS: In the low waters (limnophase, conditions in the lake were more stable, the diversity and rate of change in the community were lower, and the frequent periods of stratification and mixing were responsible for the dominance of Geitlerinema sp. (Cyanobacteria.

  18. Eukaryotic Plankton Species Diversity in the Western Channel of the Korea Strait using 18S rDNA Sequences and its Implications for Water Masses

    Science.gov (United States)

    Lee, Sang-Rae; Song, Eun Hye; Lee, Tongsup

    2018-03-01

    Organisms entering the East Sea (Sea of Japan) through the Korea Strait, together with water, salt, and energy, affect the East Sea ecosystem. In this study, we report on the biodiversity of eukaryotic plankton found in the Western Channel of the Korea Strait for the first time using small subunit ribosomal RNA gene (18S rDNA) sequences. We also discuss the characteristics of water masses and their physicochemical factors. Diverse taxonomic groups were recovered from 18S rDNA clone libraries, including putative novel, higher taxonomic entities affiliated with Cercozoa, Raphidophyceae, Picozoa, and novel marine Stramenopiles. We also found that there was cryptic genetic variation at both the intraspecific and interspecific levels among arthropods, diatoms, and green algae. Specific plankton assemblages were identified at different sampling depths and they may provide useful information that could be used to interpret the origin and the subsequent mixing history of the water masses that contribute to the Tsushima Warm Current waters. Furthermore, the biological information highlighted in this study may help improve our understanding about the complex water mass interactions that were highlighted in the Korea Strait.

  19. Feeding traits of the European flat oyster, Ostrea edulis, and the invasive Pacific oyster, Crassostrea gigas

    DEFF Research Database (Denmark)

    Nielsen, Mette; Hansen, Benni Winding; Vismann, Bent

    2017-01-01

    Two oysters, the native flat oyster, Ostrea edulis, and the non-indigenous Pacific oyster, Crassostrea gigas, have partially overlapping distributions in European waters. Relatively little is known about particle selection by O. edulis, and the goal of the present study was to establish baselines...... for particle selection by both oyster species under controlled conditions in the laboratory. The study was carried out with adult oysters of similar shell size collected in the Limfjord estuary, Denmark (56°47′N, 08°51′E), in November 2011. The feeding traits of both species [clearance rate (CR), retention...... efficiency (RE) and lower threshold for clearance (LTC)] were compared using five algal species with different cell sizes (5−32 µm ESD) (Isochrysis galbana, Rhodomonas salina, Thalassiosira weissflogii, Prorocentrum micans and Akashiwo sanguinea). Oysters were acclimated to an experimental temperature of 22...

  20. Effects of a surfacing effluent plume on a coastal phytoplankton community

    KAUST Repository

    Reifel, Kristen M.

    2013-06-01

    Urban runoff and effluent discharge from heavily populated coastal areas can negatively impact water quality, beneficial uses, and coastal ecosystems. The planned release of treated wastewater (i.e. effluent) from the City of Los Angeles Hyperion Wastewater Treatment Plant, located in Playa del Rey, California, provided an opportunity to study the effects of an effluent discharge plume from its initial release until it could no longer be detected in the coastal ocean. Non-metric multi-dimensional scaling analysis of phytoplankton community structure revealed distinct community groups based on salinity, temperature, and CDOM concentration. Three dinoflagellates (Lingulodinium polyedrum, Cochlodinium sp., Akashiwo sanguinea) were dominant (together >50% abundance) prior to the diversion. Cochlodinium sp. became dominant (65-90% abundance) within newly surfaced wastewater, and A. sanguinea became dominant or co-dominant as the effluent plume aged and mixed with ambient coastal water. Localized blooms of Cochlodinium sp. and A. sanguinea (chlorophyll a up to 100mgm-3 and densities between 100 and 2000cellsmL-1) occurred 4-7 days after the diversion within the effluent plume. Although both Cochlodinium sp. and A. sanguinea have been occasionally reported from California waters, blooms of these species have only recently been observed along the California coast. Our work supports the hypothesis that effluent and urban runoff discharge can stimulate certain dinoflagellate blooms. All three dinoflagellates have similar ecophysiological characteristics; however, small differences in morphology, nutrient preferences, and environmental requirements may explain the shift in dinoflagellate composition. © 2013 Elsevier Ltd.

  1. Application of a laser fluorometer for discriminating phytoplankton species

    Science.gov (United States)

    Chen, Peng; Pan, Delu; Mao, Zhihua

    2015-04-01

    A portable laser-induced fluorescence system for discriminating phytoplankton species has been developed. It consists of a high pulsed repetition frequency (10-kHz) microchip laser at 405 nm, a reflective fluorescent probe and a broadband micro spectrometer. The measured fluorescent spectra were overlapped by various fluorescent components, and were then decomposed by a bi-Gaussian mixture model. A spectral shape description index was designed to characterize fluorescent spectral shapes for descriminating the phytoplankton species cultured in our laboratory. Using clustering analysis, the samples of eight phytoplankton species belonging to two divisions of Bacillariophyta and Dinophyta were divided into six categories: 1) Chaetoceros debilis, Thalassiosira rotula; 2) Prorocentrum donghaiense, Prorocentrum dentatum; 3) Gymnodinium simplex; 4) Alexandrium tamarense; 5) Karenia mikimotoi; and 6) Akashiwo sanguinea. The phytoplankton species belonging to Bacillariophyta were well separated from those belonging to Dinophyta. In addition, the phytoplankton species belonging to Dinophyta were successfully distinguished from each other at genus level. The portable system is expected to be used both in vivo and in the field.

  2. Phytoplankton abundance in relation to the quality of the coastal water – Arabian Gulf, Saudi Arabia

    Directory of Open Access Journals (Sweden)

    Mostafa Abdel Mohsen El Gammal

    2017-12-01

    Full Text Available Phytoplankton abundance in relation to some physicochemical characters of the costal water of Arabian Gulf (Saudi Arabia was studied for one year. The sampling program included 15 locations in Dammam, Saihat, Al-Qatif, Al-Awamia and Safwa. Water samples were analyzed monthly for these parameters; temperature, pH, salinity, dissolved oxygen, nitrite, nitrate, ammonia, carbon dioxide, total chloride, reactive orthophosphate and total phosphorus and alkalinity, also phytoplankton communities were identified and Chlorophyll a was estimated. The results showed that, the high phytoplankton density attaining the maximum (190.3 × 104/m3 during May and June, and the minimum (10.4 × 104/m3 during November and December. Forty Five species belonging to 5 phytoplankton groups were recorded. Bacillariophyceae was the first dominant group forming 48% of the total phytoplankton communities (23 species. The dominant species of Bacillariophyceae were Pleurosigma strigosum, Pleurosigma elongatum, Lyrella clavata, Rhizosolenia shrubsolei, Cylindrotheca closterium, Nitzschia panduriform, Nitzschia longissimia, Amphora sp and Stephanopyxis. Dinophyceae was the second dominant group and formed 31% of the total phytoplankton communities (10 species; the dominant species were Ceratium fusus, Heterosigma sp, Ceratium furca, Prorocentrum triestium, Protoperidinium sp, Gyrodinium spirale, Noctiluca scintillans and Scrippsiella trochoidea. Cyanophyceae formed 13% (5 species where Nostoc sp, Oscillatoria and Merismopedia sp were the dominant species. Chlorophyceae had 8% (6 species; Scendesmus sp., Chlorella sp., Chlamydomonas sp., Dunaliella salina and Nannochloropsis sp were the dominant species. The Euglinophyceae was rare only one species (Euglina sp. The relationship was positive between the phytoplankton, chlorophyll a and carbon dioxide while negative amongst dissolved oxygen and total nitrogen. This research indicated that the relation between water quality

  3. Solid sand particle addition can enhance the production of resting cysts in dinoflagellates

    Science.gov (United States)

    Yang, Aoao; Hu, Zhangxi; Tang, Yingzhong

    2018-03-01

    Resting cysts are an important part of the life cycle for many harmful algal bloom-forming dinoflagellates, and play vital roles in the recurrence and geographical spread of harmful algal blooms. Numerous factors have been suggested to regulate the formation of resting cysts, although only a few have been proven to be significant. Cyst formation can be induced by adverse environmental conditions such as drastic changes in temperature, light, salinity, and nutrient levels, and by biological interactions. In this study, we evaluated the ability of an artificial factor (fine sand particles) to enhance the formation of resting cysts. Fine sand particles were added to cultures of dinoflagellates that are known to produce cysts. The addition of fine sand particles significantly increased both the production rate and final yield of cysts in cultures of Scrippsiella trochoidea, Biecheleria brevisulcata, and Levanderina fissa (= Gymnodinium fissum, Gyrodinium instriatum, Gyrodinium uncatenum). The largest increase in the final yield (107-fold) of cysts as a result of sand addition was in S. trochoidea. However, addition of fine sand particles did not induce cyst formation, or barely affected cyst formation, in Akashiwo sanguinea, Cochlodinium polykrikoides and Pheopolykrikos hartmannii, which are also known to be cyst-producing species. We speculated that addition of sand significantly increased the chances of cell collision, which triggered cyst formation. However, further research is required to test this idea. Importantly, our findings indicate that the addition of fine sand particles is a useful method to obtain a large quantity of cysts in a short time for laboratory studies or tests; for example, if a cyst viability test is being used to assess the effectiveness of ships' ballast water treatment.

  4. Harmful algal blooms and Vibrio spp. association in fishing and marine farming areas of mollusk bivalves in Sechura and Pisco bays, Peru

    Directory of Open Access Journals (Sweden)

    Rita Orozco

    2017-04-01

    Full Text Available Between February 2010 and May 2014, 22 surveys in Pisco and 16 in Sechura were conducted; both are major areas for shellfish production and mariculture in Peru. The incidence of Vibrio in seawater was monitored during algal blooms and in their absence. Environmental parameters such as temperature and nutrients were measured. In Sechura, Pseudo-nitzschia seriata and Protoperidinium depressum caused algal blooms and were dominant throughout the evaluation period. The temperatures in this area ranged from 21.8 to 25.3 °C. In Pisco, the harmful algal bloom-forming Akashiwo sanguinea, Messodinium rubrum, and Prorocentrum minimum and the dinoflagellate Cochlodinium polikrykoides were most prevalent. Harmful algal blooms occurred when temperatures were between 17.1 and 23.3 °C, with phosphates ranging 1.22 - 6.85 µM and nitrates 0.15 - 7.85 µM. In May 2012, the dinoflagellate Alexandrium peruvianum caused an algal bloom, with temperatures ranging 18.0 to 23.2 °C, phosphate values from 0.73 to 11.56 µM, and nitrates from 0.76 to 9.81 µM. Coliforms were low, < 2 - 23 MPN/100 ml, in both bays throughout the study period. Vibrio alginolyticus was the dominant Vibrio spp. predominated in both bays, while V. vulnificus and V. parahaemolyticus were detected in Pisco, where warmer sea temperatures are common and severe infections cases by seafood ingestion has been associated with a pathogen V. parahaemolyticus.

  5. Apical groove type and molecular phylogeny suggests reclassification of Cochlodinium geminatum as Polykrikos geminatum.

    Science.gov (United States)

    Qiu, Dajun; Huang, Liangmin; Liu, Sheng; Zhang, Huan; Lin, Senjie

    2013-01-01

    Traditionally Cocholodinium and Gymnodinium sensu lato clade are distinguished based on the cingulum turn number, which has been increasingly recognized to be inadequate for Gymnodiniales genus classification. This has been improved by the combination of the apical groove characteristics and molecular phylogeny, which has led to the erection of several new genera (Takayama, Akashiwo, Karenia, and Karlodinium). Taking the apical groove characteristics and molecular phylogeny combined approach, we reexamined the historically taxonomically uncertain species Cochlodinium geminatum that formed massive blooms in Pearl River Estuary, China, in recent years. Samples were collected from a bloom in 2011 for morphological, characteristic pigment, and molecular analyses. We found that the cingulum in this species wraps around the cell body about 1.2 turns on average but can appear under the light microscopy to be >1.5 turns after the cells have been preserved. The shape of its apical groove, however, was stably an open-ended anticlockwise loop of kidney bean shape, similar to that of Polykrikos. Furthermore, the molecular phylogenetic analysis using 18S rRNA-ITS-28S rRNA gene cistron we obtained in this study also consistently placed this species closest to Polykrikos within the Gymnodinium sensu stricto clade and set it far separated from the clade of Cochlodinium. These results suggest that this species should be transferred to Polykrikos as Polykrikos geminatum. Our results reiterate the need to use the combination of apical groove morphology and molecular phylogeny for the classification of species within the genus of Cochlodinium and other Gymnodiniales lineages.

  6. Apical groove type and molecular phylogeny suggests reclassification of Cochlodinium geminatum as Polykrikos geminatum.

    Directory of Open Access Journals (Sweden)

    Dajun Qiu

    Full Text Available Traditionally Cocholodinium and Gymnodinium sensu lato clade are distinguished based on the cingulum turn number, which has been increasingly recognized to be inadequate for Gymnodiniales genus classification. This has been improved by the combination of the apical groove characteristics and molecular phylogeny, which has led to the erection of several new genera (Takayama, Akashiwo, Karenia, and Karlodinium. Taking the apical groove characteristics and molecular phylogeny combined approach, we reexamined the historically taxonomically uncertain species Cochlodinium geminatum that formed massive blooms in Pearl River Estuary, China, in recent years. Samples were collected from a bloom in 2011 for morphological, characteristic pigment, and molecular analyses. We found that the cingulum in this species wraps around the cell body about 1.2 turns on average but can appear under the light microscopy to be >1.5 turns after the cells have been preserved. The shape of its apical groove, however, was stably an open-ended anticlockwise loop of kidney bean shape, similar to that of Polykrikos. Furthermore, the molecular phylogenetic analysis using 18S rRNA-ITS-28S rRNA gene cistron we obtained in this study also consistently placed this species closest to Polykrikos within the Gymnodinium sensu stricto clade and set it far separated from the clade of Cochlodinium. These results suggest that this species should be transferred to Polykrikos as Polykrikos geminatum. Our results reiterate the need to use the combination of apical groove morphology and molecular phylogeny for the classification of species within the genus of Cochlodinium and other Gymnodiniales lineages.

  7. Combined effects of the herbicide terbuthylazine and temperature on different flagellates from the Northern Adriatic Sea.

    Science.gov (United States)

    Fiori, Emanuela; Mazzotti, Matilde; Guerrini, Franca; Pistocchi, Rossella

    2013-03-15

    The triazinic herbicide terbuthylazine (TBA) is becoming an emergent contaminant in Italian rivers and in coastal and groundwater. A preliminary analysis of the sensitivity of marine flagellates to TBA was performed by monitoring the photosynthetic efficiency of nine species (belonging to the Dinophyceae or Raphidophyceae class) isolated from the Adriatic Sea. Different sensitivity levels for each flagellate were observed and the most sensitive microalgae, based on PSII inhibition, were: Gonyaulax spinifera>Fibrocapsa japonica>Lingulodinium polyedrum while the most resistant were two species belonging to the Prorocentrum genus. Then the response of two microalgae to drivers, such as temperature and terbuthylazine, applied in combination was also investigated. Two potentially toxic flagellates, Prorocentrum minimum and G. spinifera, were exposed, under different temperature conditions (15, 20 and 25°C), to TBA concentrations that did not completely affect PSII. For both flagellates, effects of TBA on algal growth, measured through cell density and carbon analysis, as well as on the photosynthetic activity are reported. All parameters analyzed showed a negative effect of TBA from the exponential phase. TBA effect on algal growth was significantly enhanced at the optimal temperature conditions (20 and 25°C), while no difference between control and herbicide treatments were detected for G. spinifera grown at 15°C, which represented a stress condition for this species. The maximum inhibition of photosynthetic efficiency was found at 20°C for both organisms. Both flagellates increased cell carbon and nitrogen content in herbicide treatments compared to the control, except G. spinifera grown at 15°C. Chlorophyll-a production was increased only in G. spinifera exposed to 5 μg L(-1) of TBA and the effect was enhanced with the increase of temperature. Herbicide-induced variations in cellular components determined changes in cellular carbon:nitrogen (C:N) and

  8. Feeding by phototrophic red-tide dinoflagellates on the ubiquitous marine diatom Skeletonema costatum.

    Science.gov (United States)

    Du Yoo, Yeong; Jeong, Hae Jin; Kim, Mi Seon; Kang, Nam Seon; Song, Jae Yoon; Shin, Woongghi; Kim, Kwang Young; Lee, Kitack

    2009-01-01

    We investigated feeding by phototrophic red-tide dinoflagellates on the ubiquitous diatom Skeletonema costatum to explore whether dinoflagellates are able to feed on S. costatum, inside the protoplasm of target dinoflagellate cells observed under compound microscope, confocal microscope, epifluorescence microscope, and transmission electron microscope (TEM) after adding living and fluorescently labeled S. costatum (FLSc). To explore effects of dinoflagellate predator size on ingestion rates of S. costatum, we measured ingestion rates of seven dinoflagellates at a single prey concentration. In addition, we measured ingestion rates of the common phototrophic dinoflagellates Prorocentrum micans and Gonyaulax polygramma on S. costatum as a function of prey concentration. We calculated grazing coefficients by combining field data on abundances of P. micans and G. polygramma on co-occurring S. costatum with laboratory data on ingestion rates obtained in the present study. All phototrophic dinoflagellate predators tested (i.e. Akashiwo sanguinea, Amphidinium carterae, Alexandrium catenella, Alexandrium tamarense, Cochlodinium polykrikoides, G. polygramma, Gymnodinium catenatum, Gymnodinium impudicum, Heterocapsa rotundata, Heterocapsa triquetra, Lingulodinium polyedrum, Prorocentrum donghaiense, P. micans, Prorocentrum minimum, Prorocentrum triestinum, and Scrippsiella trochoidea) were able to ingest S. costatum. When mean prey concentrations were 170-260 ng C/ml (i.e. 6,500-10,000 cells/ml), the ingestion rates of G. polygramma, H. rotundata, H. triquetra, L. polyedrum, P. donghaiense, P. micans, and P. triestinum on S. costatum (0.007-0.081 ng C/dinoflagellate/d [0.2-3.0 cells/dinoflagellate/d]) were positively correlated with predator size. With increasing mean prey concentration of ca 1-3,440 ng C/ml (40-132,200 cells/ml), the ingestion rates of P. micans and G. polygramma on S. costatum continuously increased. At the given prey concentrations, the maximum ingestion