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  • Low-dose stimulation of growth of the harmful alga, Prymnesium parvum, by glyphosate and glyphosate-based herbicides
    Harmful Algae (IF 4.138) Pub Date : 2018-11-17
    Brittanie L. Dabney, Reynaldo Patiño

    Glyphosate-based herbicides (GBH) are widely used around the globe. While generally toxic to phototrophs, organic phosphorus in glyphosate can become available to glyphosate-resistant phytoplankton and contribute to algal bloom development. Few studies have examined the effects of GBH on growth of eukaryotic microalgae and information for the toxic bloom-forming haptophyte, Prymnesium parvum, is limited. Using a batch-culture system, this study examined the effects on P. parvum growth of a single application of Roundup Weed and Grass Killer Super Concentrate Plus® (Roundup SC), Roundup Weed and Grass Killer Ready-to-Use III® (Roundup RtU), and technical-grade glyphosate at low concentrations [0–1000 μg glyphosate acid equivalent (ae) l−1]. Roundup formulations differ in the percent of glyphosate as active ingredient (Roundup SC, ∼50%; Roundup RtU, 2%), allowing indirect evaluation of the influence of inactive ingredients. Roundup SC enhanced exponential growth rate at 10–1000 μg glyphosate ae l−1, and a positive monotonic association was noted between Roundup SC concentration and early (pre-exponential growth) but not maximum cell density. Glyphosate and both Roundup formulations enhanced growth rate at 100 μg glyphosate l−1, but only Roundup SC and glyphosate significantly stimulated early and maximum density. This observation suggests the higher concentration of inactive ingredients and other compounds in Roundup RtU partially counteracts glyphosate-dependent growth stimulation. When phosphate concentration was varied while maintaining other conditions constant, addition of Roundup SC and glyphosate at 100 μg l−1 influenced growth more strongly than equivalent changes in phosphate-associated phosphorus. It appears, therefore, that low doses of glyphosate stimulate growth by mechanisms unrelated to the associated small increases in total phosphorus. In conclusion, glyphosate and GBH stimulate P. parvum growth at low, environmentally relevant concentrations. This finding raises concerns about the potential contribution to P. parvum blooms by glyphosate-contaminated runoff or by direct application of GBH to aquatic environments.

    更新日期:2018-11-17
  • Analysis of free and metabolized microcystins in samples following a bird mortality event
    Harmful Algae (IF 4.138) Pub Date : 2018-11-03
    Amanda J. Foss, Christopher O. Miles, Ingunn A. Samdal, Kjersti E. Løvberg, Alistair L. Wilkins, Frode Rise, J. Atle H. Jaabæk, Peter C. McGowan, Mark T. Aubel

    In the summer of 2012, over 750 dead and dying birds were observed at the Paul S. Sarbanes Ecosystem Restoration Project at Poplar Island, Maryland, USA (Chesapeake Bay). Clinical signs suggested avian botulism, but an ongoing dense Microcystis bloom was present in an impoundment on the island. Enzyme-linked immunosorbent assay (ELISA) analysis of a water sample indicated 6000 ng mL−1 of microcystins (MCs). LC-UV/MS analysis confirmed the presence of MC-LR and a high concentration of an unknown MC congener (m/z 1037.5). The unknown MC was purified and confirmed to be [D-Leu1]MC-LR using NMR spectroscopy, LC-HRMS and LC–MS2, which slowly converted to [D-Leu1,Glu(OMe)6]MC-LR during storage in MeOH. Lyophilized algal material from the bloom was further characterized using LC-HRMS and LC–MS2 in combination with chemical derivatizations, and an additional 24 variants were detected, including MCs conjugated to Cys, GSH and γ-GluCys and their corresponding sulfoxides. Mallard (Anas platyrhynchos) livers were tested to confirm MC exposure. Two broad-specificity MC ELISAs and LC–MS2 were used to measure free MCs, while ‘total’ MCs were estimated by both MMPB (3-methoxy-2-methyl-4-phenylbutyric acid) and thiol de-conjugation techniques. Free microcystins in the livers (63–112 ng g−1) accounted for 33–41% of total microcystins detected by de-conjugation and MMPB techniques. Free [D-Leu1]MC-LR was quantitated in tissues at 25–67 ng g−1 (LC–MS2). The levels of microcystin varied based on analytical method used, highlighting the need to develop a comprehensive analysis strategy to elucidate the etiology of bird mortality events when microcystin-producing HABs are present.

    更新日期:2018-11-05
  • Pseudo-nitzschia, Nitzschia, and domoic acid: New research since 2011
    Harmful Algae (IF 4.138) Pub Date : 2018-10-27
    Stephen S. Bates, Katherine A. Hubbard, Nina Lundholm, Marina Montresor, Chui Pin Leaw

    Some diatoms of the genera Pseudo-nitzschia and Nitzschia produce the neurotoxin domoic acid (DA), a compound that caused amnesic shellfish poisoning (ASP) in humans just over 30 years ago (December 1987) in eastern Canada. This review covers new information since two previous reviews in 2012. Nitzschia bizertensis was subsequently discovered to be toxigenic in Tunisian waters. The known distribution of N. navis-varingica has expanded from Vietnam to Malaysia, Indonesia, the Philippines and Australia. Furthermore, 15 new species (and one new variety) of Pseudo-nitzschia have been discovered, bringing the total to 52. Seven new species were found to produce DA, bringing the total of toxigenic species to 26. We list all Pseudo-nitzschia species, their ability to produce DA, and show their global distribution. A consequence of the extended distribution and increased number of toxigenic species worldwide is that DA is now found more pervasively in the food web, contaminating new marine organisms (especially marine mammals), affecting their physiology and disrupting ecosystems. Recent findings highlight how zooplankton grazers can induce DA production in Pseudo-nitzschia and how bacteria interact with Pseudo-nitzschia. Since 2012, new discoveries have been reported on physiological controls of Pseudo-nitzschia growth and DA production, its sexual reproduction, and infection by an oomycete parasitoid. Many advances are the result of applying molecular approaches to discovering new species, and to understanding the population genetic structure of Pseudo-nitzschia and mechanisms used to cope with iron limitation. The availability of genomes from three Pseudo-nitzschia species, coupled with a comparative transcriptomic approach, has allowed advances in our understanding of the sexual reproduction of Pseudo-nitzschia, its signaling pathways, its interactions with bacteria, and genes involved in iron and vitamin B12 and B7 metabolism. Although there have been no new confirmed cases of ASP since 1987 because of monitoring efforts, new blooms have occurred. A massive toxic Pseudo-nitzschia bloom affected the entire west coast of North America during 2015–2016, and was linked to a ‘warm blob’ of ocean water. Other smaller toxic blooms occurred in the Gulf of Mexico and east coast of North America. Knowledge gaps remain, including how and why DA and its isomers are produced, the world distribution of potentially toxigenic Nitzschia species, the prevalence of DA isomers, and molecular markers to discriminate between toxigenic and non-toxigenic species and to discover sexually reproducing populations in the field.

    更新日期:2018-10-27
  • MHBMDAA: Membrane-based DNA array with high resolution and sensitivity for toxic microalgae monitoring
    Harmful Algae (IF 4.138) Pub Date : 2018-10-19
    Chunyun Zhang, Guofu Chen, Yuanyuan Wang, Rui Sun, Xiaoli Nie, Jin Zhou

    Harmful algal blooms (HAB) involving toxic microalgae have posed a serious threat to the marine industry and environment in the past several decades. Efficient techniques are required to monitor the marine environment to provide an effective warning of imminent HAB. Sequenced the partial large subunit rDNA (D1-D2) sequences of eight toxic harmful algae that are commonly distributed along the Chinese coast were cloned. Specific padlock probes (PLP) that contain linker regions composed of universal primer binding sites and Zip sequences were designed from the obtained target DNA. Taxonomic probes complementary to the Zip sequences were tailed and spotted onto a nylon membrane to prepare a DNA array. An optimized multiplex hyperbranched rolling circle amplification (MHRCA) was used to produce biotin-labeled amplified products. Heat-denatured MHRCA products were used to hybridize with DNA array, followed by dot coloration. An MHRCA-based membrane DNA array assay (MHBMDAA) for detecting toxic microalgae was developed. The specificity of the MHBMDAA was confirmed by double cross-reactivity tests of PLP and taxonomic probes. The MHBMDAA was competent for detecting the simulated samples with 103 to 10−1 cells mL−1, which is 10-fold more sensitive than a multiplex PCR-based membrane DNA array. The effectiveness of the MHBMDAA was also validated by testing with natural samples from the East China Sea. Results indicated that the MHBMDAA provides a valuable tool for the sensitive and reliable detection of toxic microalgae for early warning and research purposes.

    更新日期:2018-10-22
  • The successional formation and release of domoic acid in a Pseudo-nitzschia bloom in the Juan de Fuca Eddy: A drifter study
    Harmful Algae (IF 4.138) Pub Date : 2018-10-21
    Charles G. Trick, Vera L. Trainer, William P. Cochlan, Mark L. Wells, B.F. Beall

    Blooms of Pseudo-nitzschia species are frequent, but presently unpredictable, in the Juan de Fuca Eddy region off the coasts of Washington (US) and British Columbia (Canada). This upwelling eddy region is proposed to be the bloom commencement site, before cells are entrained into the coastal surface currents. During a shipboard study, we characterized the different stages of the Pseudo-nitzschia bloom development from its initiation and intensification, to its eventual sinking and dissipation. Specifically, we followed a water mass using lagrangian ARGOS-tracked drifters released at the eddy water mass and quantified production of dissolved and particulate domoic acid, and the physiological status of the Pseudo-nitzschia cells with regards to photosynthesis, nutrient needs and sinking rates, along with its relationship with competing species – in this case, the marine euglenoid, Eutreptiella spp. The drifter study allows for an interpretation of the presence or absence of Pseudo-nitzschia and domoic acid against active environmental factors – particularly copper and iron.

    更新日期:2018-10-22
  • A Greek Cylindrospermopsis raciborskii strain: Missing link in tropic invader’s phylogeography tale
    Harmful Algae (IF 4.138) Pub Date : 2018-10-15
    Manthos Panou, Sevasti-Kiriaki Zervou, Triantafyllos Kaloudis, Anastasia Hiskia, Spyros Gkelis
    更新日期:2018-10-15
  • Anatoxins are consistently released into the water of streams with Microcoleus autumnalis-dominated (cyanobacteria) proliferations
    Harmful Algae (IF 4.138) Pub Date : 2018-10-10
    Susanna A. Wood, Laura Biessy, Jonathan Puddick

    Proliferations of potentially toxic, mat-forming Microcoleus are increasing in streams globally. A range of cyanotoxins are produced by Microcoleus, with the neurotoxic anatoxins (anatoxin-a, dihydro-anatoxin-a, homoanatoxin-a and dihydro-homoanatoxin-a) the most commonly reported. The anatoxins produced by Microcoleus are thought to be largely contained within the cells. More knowledge on whether anatoxins are been released into the overlying stream water is required to better assess health risks to human, animals, and aquatic organisms. Field studies were conducted in three streams experiencing toxic Microcoleus autumnalis (basionym Phormidium autumnale)-dominated proliferations. Samples were collected every 1.5–3 h over a 24- or 26-h sampling period. Water samples were analyzed for total (intracellular and dissolved) and dissolved anatoxins, and time-integrated anatoxin samples were collected using solid phase adsorption tracking technology (SPATT). Anatoxins were detected in all stream water and SPATT samples (max. 0.91 ng mL−1 and 95 ng g-1 of strata-x hr−1). At two sites, anatoxins were largely dissolved, whereas at the third site only total anatoxins could be detected. Temporal variability in anatoxin concentrations was observed, but there were no evident patterns between sampling sites. Linear regression showed a very weakstatistically significant relationship (R2 = 0.24, p = 0.002) between total anatoxin concentrations in water and SPATT, however, when tested per site, only one of the three showed a significant relationship. These results highlight the potential for chronic exposure to anatoxins for humans (i.e., through drinking water) and aquatic organisms in streams with M. autumnalis proliferations. The health implications of this are unknown.

    更新日期:2018-10-11
  • Development of an LC–MS/MS method to simultaneously monitor maitotoxins and selected ciguatoxins in algal cultures and P-CTX-1B in fish
    Harmful Algae (IF 4.138) Pub Date : 2018-10-09
    J. Sam Murray, Michael J. Boundy, Andrew I. Selwood, D. Tim Harwood
    更新日期:2018-10-09
  • Isolation of an algicidal bacterium and its effects against the harmful-algal- bloom dinoflagellate Prorocentrum donghaiense (Dinophyceae)
    Harmful Algae (IF 4.138) Pub Date : 2018-10-06
    Xinguo Shi, Lemian Liu, Yue Li, Yuchun Xiao, Guangmao Ding, Senjie Lin, Jianfeng Chen

    The relationship between algicidal bacteria and harmful-algal-bloom-forming dinoflagellates is understudied and their action modes are largely uncharacterized. In this study, an algicidal bacterium (FDHY-03) was isolated from a bloom of Prorocentrum donghaiense and the characteristics of its action against P. donghaiense was investigated at physiological, molecular, biochemical and cytological levels. 16S rDNA sequence analysis placed this strain in the genus of Alteromonas in the subclass of γ-proteobacteria. Algicidal activity was detected in the bacterial filtrate, suggesting a secreted algicidal principle from this bacterium. Strain FDHY-03 showed algicidal activity on a broad range of HAB-forming species, but the greatest effect was found on P. donghaiense, which showed 91.7% mortality in 24 h of challenge. Scanning electron microscopic analysis indicated that the megacytic growth zone of P. donghaiense cells was the major target of the algicidal action of FDHY-03. When treated with FDHY-03 culture filtrate, P. donghaiense cell wall polysaccharides decreased steadily, suggesting that the algicidal activity occurred through the digestion of cell wall polysaccharides. To verify this proposition, the expression profile of beta-glucosidase gene in FDHY-03 cultures with or without P. donghaiense cell addition was investigated using reverse-transcription quantitative PCR. The gene expression level increased in the presence of P. donghaiense cells, indicative of beta-glucosidase induction by P. donghaiense and the enzyme’s role in this dinoflagellate’s demise. This study has isolated a new bacterial strain with a strong algicidal capability, documented its action mode and biochemical mechanism, providing a potential source of bacterial agent to control P. donghaiense blooms.

    更新日期:2018-10-08
  • Habitat effects on Ostreopsis cf. ovata bloom dynamics
    Harmful Algae (IF 4.138) Pub Date : 2018-10-05
    L. Meroni, M. Chiantore, M. Petrillo, V. Asnaghi

    In the last few decades, Ostreopsis spp., toxic benthic dinolagellates of tropical origin, generated large interest in the Mediterranean Sea, where several bloom events have been observed. Ecology and proliferation dynamics of O. cf. ovata are driven by complex interactions among biotic and abiotic drivers, and understanding mechanisms triggering bloom events is still far from being complete. The aim of the present study is to highlight the role of different habitat conditions, elucidating the effects of i) exposure to hydrodynamic conditions, ii) macroalgal community and iii) urbanisation level, in driving O. cf. ovata bloom dynamics. A significant effect of hydrodynamics was observed only for cells in seawater, with higher abundances in sheltered zones, irrespective of the urbanisation level. Similarly, a significant effect of the dominant macroalgal community, with higher abundances in Corallinales and turf dominated communities, and lower ones in Cystoseira amentacea canopies, has been recorded, consistently in the differently urbanised sites. Additionally, stretches of the coast suffering from a more intense anthropic exploitation are in general more prone to the proliferation of potentially toxic benthic microalgae. All these results imply a larger risk exposure to toxic effects for humans in urban beaches and sheltered areas, usually more attended by swimmers and bathers. These findings underline the need to preserve, and eventually restore, canopy dominated assemblages, which presently are under regression because of human threats, providing a straightforward example that restoration of relevant habitats implies a cascading improvement of human welfare.

    更新日期:2018-10-06
  • Production of domoic acid from large-scale cultures of Pseudo-nitzschia multiseries: A feasibility study
    Harmful Algae (IF 4.138) Pub Date : 2018-10-06
    Nancy I. Lewis, Stephen S. Bates, Michael A. Quilliam

    The commercial demand for domoic acid (DA), the phycotoxin responsible for Amnesic Shellfish Poisoning, is currently met by extraction from a diminishing supply of stockpiled contaminated mussels (Mytilus edulis). As this supply becomes scarce, a more reliable source is needed. Purification of the toxin from an algal source would be easier and more economical than from shellfish tissue if algal growth and yield of toxin were maximized. This project was initiated to determine if DA could be produced using large-scale semi-continuous algal cultures, which should reduce labour and shorten the time required for biomass production. Pseudo-nitzschia multiseries was grown in 300-L fibreglass photobioreactors called a Brite-Box™. The effect of temperature and nutrient depletion on the yield of DA by P. multiseries was examined. A decline in maximum cell number without a substantial increase in cellular DA was associated with increased temperature. Maximum total cellular DA (8.8 pg cell−1) was achieved at 20 °C. Semi-continuous culture of P. multiseries is accompanied by increasing amounts of DA lost to the medium. The process was deemed to be feasible for growing P. multiseries but methods to recover this extracellular DA are necessary for this process to be economical.

    更新日期:2018-10-06
  • Fish gill damage by harmful microalgae newly explored by microelectrode ion flux estimation techniques
    Harmful Algae (IF 4.138) Pub Date : 2018-09-28
    Jorge I. Mardones, Lana Shabala, Sergey Shabala, Juan José Dorantes-Aranda, Andreas Seger, Gustaaf M. Hallegraeff

    Harmful algal blooms (HAB) are responsible for massive mortalities of wild and aquacultured fish due to noticeable gill damage, but the precise fish-killing mechanisms remain poorly understood. A non-invasive microelectrode ion flux estimation (MIFE) technique was successfully applied to assess changes in membrane-transport processes in a model fish gill cell line exposed to harmful microplankton. Net Ca2+, H+, K+ ion fluxes in the rainbow trout cell line RTgill-W1 were monitored before and after addition of lysed cells of this Paralytic Shellfish Toxins (PST) producer along with purified endocellular dinoflagellate PST. It was demonstrated that PST alone do not play a role in fish gill damage during A. catenella outbreaks as previously thought, but that other ichthyotoxic metabolites from lysed algal cells (i.e. lipid peroxidation products or other unknown metabolites) result in net K+ efflux from fish gill cells and thereby gill cell death.

    更新日期:2018-09-28
  • Effects of light intensity, temperature, and salinity on the growth and ingestion rates of the red-tide mixotrophic dinoflagellate Paragymnodinium shiwhaense
    Harmful Algae (IF 4.138) Pub Date : 2018-09-27
    Hae Jin Jeong, Kyung Ha Lee, Yeong Du Yoo, Nam Seon Kang, Jae Yoon Song, Tae Hoon Kim, Kyeong Ah Seong, Jae Seong Kim, Eric Potvin

    Among mixotrophic dinoflagellates, the maximum mixotrophic growth rate of the red-tide dinoflagellate Paragymnodinium shiwhaense is relatively high, whereas mortality due to predation is low. To investigate the effects of major environmental parameters on P. shiwhaense, growth and ingestion rates of one strain of P. shiwhaense on the algal prey species Amphidinium carterae (also a dinoflagellate) were determined under various light intensities (0–500 μE m−2s-1), water temperatures (5–30 °C), and salinities (5–40). Cells of P. shiwhaense did not grow well in darkness but grew well at light intensities ≥ 10 μE m−2s-1. There were no significant differences in either growth or ingestion rates of P. shiwhaense fed A. carterae at light intensities between 10 and 500 μE m−2s-1. Furthermore, P. shiwhaense did not grow at 5 °C or ≥ 28 °C. Its growth rates between 7 and 26 °C were significantly affected by temperature, and the optimal temperature for maximal growth was 25 °C. With increasing salinity from 5 to 20, the growth rate of P. shiwhaense fed A. carterae increased and became saturated at salinities between 20 and 40, while the ingestion rate at salinities between 10 and 40 did not significantly change. Thus, overall, the growth and ingestion rates of P. shiwhaense fed A. carterae were affected by temperature and salinity, but not by light intensity other than darkness. These findings provide a beginning basis for understanding the ecology of this potentially harmful algal species in marine coastal ecosystems.

    更新日期:2018-09-27
  • Economic and sociocultural impacts of fisheries closures in two fishing-dependent communities following the massive 2015 U.S. West Coast harmful algal bloom
    Harmful Algae (IF 4.138) Pub Date : 2018-09-27
    Jerilyn Ritzman, Amy Brodbeck, Sara Brostrom, Scott McGrew, Stacia Dreyer, Terrie Klinger, Stephanie K. Moore

    In the spring of 2015, a massive harmful algal bloom (HAB) of the toxin-producing diatom Pseudo-nitzschia occurred on the U.S. West Coast, resulting in the largest recorded outbreak of the toxin domoic acid and causing fisheries closures. Closures extended into 2016 and generated an economic shock for coastal fishing communities. This study examines the economic and sociocultural impacts of the Dungeness crab and razor clam fisheries closures on two fishing-dependent communities. Semi-structured interviews were conducted with 36 community members from two communities impacted by the event – Crescent City, California and Long Beach, Washington. Interviewees included those involved in the fishing, hospitality, and retail industries, local government officials, recreational harvesters, and others. Interviews probed aspects of resilience in economic, social, institutional, and physical domains, based on the contention that community resilience will influence the communities’ ability to withstand HAB events. Dimensions of vulnerability were also explored, encompassing sensitivity of the communities to HAB events and their adaptive capacity. Common themes that emerged from the interview responses indicate that economic hardships extended beyond fishing-related operations and permeated through other sectors, particularly the hospitality industry. Significant barriers to accessing financial and employment assistance during extended fisheries closures were identified, particularly for fishers. Long-held traditions surrounding crab and shellfish harvest and consumption were disrupted, threatening the cultural identities of the affected communities. Community members expressed a desire for clearer, more thorough, and more rapid dissemination of information regarding the management of fisheries closures and the health risks associated with HAB toxins. The likelihood of intensifying HABs under climate change heightens the need for actions to increase the resilience of fishing communities to the economic and sociocultural impacts caused by HAB-related fisheries closures.

    更新日期:2018-09-27
  • Can domoic acid affect escape response in copepods?
    Harmful Algae (IF 4.138) Pub Date : 2018-09-21
    Sara Harðardóttir, Bernd Krock, Sylke Wohlrab, Uwe John, Torkel Gissel Nielsen, Nina Lundholm

    Copepods are important grazers on toxic phytoplankton and serve as vectors for algal toxins up the marine food web. Success of phytoplankton depends among other factors on protection against grazers like copepods, and same way copepod survival and population resilience relies on their ability to escape predators. Little is, however, known about the effect of toxins on the escape response of copepods. In this study we experimentally tested the hypothesis that the neurotoxin domoic acid (DA) produced by the diatom Pseudo-nitzschia affects escape responses of planktonic copepods. We found that the arctic copepods Calanus hyperboreus and C. glacialis reduced their escape response after feeding on a DA-producing diatom. The two species were not affected the same way; C. hyperboreus was affected after shorter exposure and less intake of DA. The negative effect on escape response was not related to the amount of DA accumulated in the copepods. Our results suggest that further research on the effects of DA on copepod behavior and DA toxicity mechanisms is required to evaluate the anti-grazing function of DA.

    更新日期:2018-09-25
  • Diversity, distribution, and azaspiracids of Amphidomataceae (Dinophyceae) along the Norwegian coast
    Harmful Algae (IF 4.138) Pub Date : 2018-09-20
    Urban Tillmann, Bente Edvardsen, Bernd Krock, Kirsty F. Smith, Ruth F. Paterson, Daniela Voß

    Azaspiracids (AZA) are a group of lipophilic polyether compounds which have been implicated in shellfish poisoning incidents around Europe. They are produced by a few species of the dinophycean genera Azadinium and Amphidoma (Amphidomataceae). The presence of AZA toxins in Norway is well documented, but knowledge of the distribution and diversity of Azadinium and other Amphidomataceae along the Norwegian coast is rather limited and poorly documented. On a research survey along the Norwegian coast in 2015 from the Skagerrak in the South to Trondheimsfjorden in the North, plankton samples from 67 stations were analysed for the presence of Azadinium and Amphidoma and their respective AZA by on-board live microscopy, real-time PCR assays specific for Amphidomataceae, and liquid chromatography-tandem mass spectrometry (LC–MS/MS). Microscopy using live samples and positive real-time PCR assays using a general family probe and two species specific probes revealed the presence of Amphidomataceae distributed throughout the sampling area. Overall abundance was low, however, and was in agreement with a lack of detectable AZA in plankton samples. Single cell isolation and morphological and molecular characterisation of established strains revealed the presence of 7 amphidomatacean species (Azadiniun spinosum, Az. poporum, Az. obesum, Az. dalianense, Az. trinitatum, Az. polongum, Amphidoma languida) in the area. Azaspiracids were produced by the known AZA producing species Az. spinosum, Az. poporum and Am. languida only. LC–MS/MS analysis further revealed that Norwegian strains produce previously unreported AZA for Norway (AZA-11 by Az. spinosum, AZA-37 by Az. poporum, AZA-38 and AZA-39 by Am. languida), and also four novel compounds (AZA-50, -51 by Az. spinosum, AZA-52, -53 by Am. languida), whose structural properties are described and which now can be included in existing analytical protocols. A maximum likelihood analysis of concatenated rDNA regions (SSU, ITS1-ITS2, partial LSU) showed that the strains of Az. spinosum fell in two well supported clades, where most but not all new Norwegian strains formed the new Ribotype B. Ribotype differentiation was supported by a minor morphological difference with respect to the presence/absence of a rim around the pore plate, and was consistently reflected by different AZA profiles. Strains of Az. spinosum from ribotype A produce AZA-1, -2 and -33, whereas the new strains of ribotype B produce mainly AZA-11 and AZA-51. Significant sequence differences between both Az. spinosum ribotypes underline the need to redesign the currently used qPCR probes in order to detect all AZA producing Az. spinosum. The results generally underline the conclusion that for the Norwegian coast area it is important that amphidomatacean species are taken into account in future studies and monitoring programs.

    更新日期:2018-09-21
  • Insights into the dynamics of harmful algal blooms in a tropical estuary through an integrated hydrodynamic-Pyrodinium-shellfish model
    Harmful Algae (IF 4.138) Pub Date : 2018-09-07
    Aletta T. Yñiguez, Jennifer Maister, Cesar L. Villanoy, Josephine Dianne Deauna, Eileen Peñaflor, Aldwin Almo, Laura T. David, Garry A. Benico, Ellen Hibay, Irmi Mora, Sandra Arcamo, Jun Relox, Rhodora V. Azanza

    In contrast to temperate Harmful Algal Blooms (HABs), knowledge on the mechanisms driving tropical HABs are less well studied. The interaction of a seasonal temperature window, cysts (for certain species) and large-scale transport are some of the key processes in temperate HABs. In the Philippines, HABs occur not along long open coastlines, but in embayments that are highly influenced by run-off and stratification. These embayments are typically also the sites of cultured or wild harvest shellfish and other aquaculture activities. Sorsogon Bay in the northeastern Philippines has experienced prolonged shellfish-harvesting bans due to blooms by Pyrodinium bahamense var. compressum severely affecting the fisheries industry in this area, as well as leading to Paralytic Shellfish Poisoning illnesses and fatalities. A novel integrated model was developed that mechanistically captures the interactions between hydrodynamic conditions, nutrients, the life history (cells and cysts) of Pyrodinium, as well as the cultured shellfish within the bay and their ensuing toxicities due to ingestion of toxic Pyrodinium cells and cysts. This is the second model developed for HABs in the Philippines, and the first to integrate different components of Pyrodinium bloom dynamics. The model is modularly composed of a watershed nutrient and diffusion model, a 3D hydrodynamic model, a Pyrodinium population model and a shellfish toxin model. It was able to capture the observed temporal variations of Pyrodinium and shellfish toxicity. It was also able to represent some aspects of the spatial distribution in Sorsogon Bay though there were discrepancies. To explore the dynamics of blooms, the linkages between the bloom and decline of the Pyrodinium population with shellfish toxicity as affected by temperature, salinity and nutrients were investigated. Comparisons with field results showed the seasonality of blooms in Sorsogon Bay is driven by increased rainfall. The timing of these conditions is important in facilitating Pyrodinium excystment and reproduction. Model results showed as well the potential significance of shellfish grazing and dinoflagellate cell mortality in influencing the decline of the bloom, and toxicity levels. This approach is promising in helping to understand mechanisms for HABs more holistically, and the model can be further improved to provide more precise quantitative information.

    更新日期:2018-09-09
  • Repeated low level domoic acid exposure increases CA1 VGluT1 levels, but not bouton density, VGluT2 or VGAT levels in the hippocampus of adult mice
    Harmful Algae (IF 4.138) Pub Date : 2018-09-05
    Caitlin E. Moyer, Emma M. Hiolski, David J. Marcinek, Kathi A. Lefebvre, Donald R. Smith, Yi Zuo

    Domoic acid (DA) is a neurotoxin produced during harmful algal blooms that accumulates in marine organisms that serve as food resources for humans. While acute DA neurotoxicity can cause seizures and hippocampal lesions, less is known regarding how chronic, subacute DA exposure in adulthood impacts the hippocampus. With more frequent occurrences of harmful algal blooms, it is important to understand the potential impact of repeated, low-level DA exposure on human health. To model repeated, low-dose DA exposure, adult mice received a single low-dose (0.75 ± 0.05 μg/g) of DA or vehicle weekly for 22 consecutive weeks. Quantitative immunohistochemistry was performed to assess the effects of repeated, low-level DA exposure on hippocampal cells and synapses. Vesicular glutamate transporter 1 (VGluT1) immunoreactivity within excitatory boutons in CA1 of DA-exposed mice was increased. Levels of other vesicular transporter proteins (i.e., VGluT2 and the vesicular GABA transporter (VGAT)) within boutons, and corresponding bouton densities, were not significantly altered in CA1, CA3, or dentate gyrus. There were no significant changes in neuron density or glial fibrillary acidic protein (GFAP) immunoreactivity following chronic, low-dose exposure. This suggests that repeated low doses of DA, unlike high doses of DA, do not cause neuronal loss or astrocyte activation in hippocampus in adult mice. Instead, these findings demonstrate that repeated exposure to low levels of DA leads to subtle changes in VGluT1 expression within CA1 excitatory boutons, which may alter glutamatergic transmission in CA1 and disrupt behaviors dependent on spatial memory.

    更新日期:2018-09-05
  • Diversity and toxicity of Pseudo-nitzschia species in Monterey Bay: Perspectives from targeted and adaptive sampling
    Harmful Algae (IF 4.138) Pub Date : 2018-08-31
    Holly A. Bowers, John P. Ryan, Kendra Hayashi, April L. Woods, Roman Marin, G. Jason Smith, Katherine A. Hubbard, Gregory J. Doucette, Christina M. Mikulski, Alyssa G. Gellene, Yanwu Zhang, Raphael M. Kudela, David A. Caron, James M. Birch, Christopher A. Scholin

    Monterey Bay, California experiences near-annual blooms of Pseudo-nitzschia that can affect marine animal health and the economy, including impacts to tourism and commercial/recreational fisheries. One species in particular, P. australis, has been implicated in the most toxic of events, however other species within the genus can contribute to widespread variability in community structure and associated toxicity across years. Current monitoring methods are limited in their spatial coverage as well as their ability to capture the full suite of species present, thereby hindering understanding of HAB events and limiting predictive accuracy. An integrated deployment of multiple in situ platforms, some with autonomous adaptive sampling capabilities, occurred during two divergent bloom years in the bay, and uncovered detailed aspects of population and toxicity dynamics. A bloom in 2013 was characterized by spatial differences in Pseudo-nitzschia populations, with the low-toxin producer P. fraudulenta dominating the inshore community and toxic P. australis dominating the offshore community. An exceptionally toxic bloom in 2015 developed as a diverse Pseudo-nitzschia community abruptly transitioned into a bloom of highly toxic P. australis within the time frame of a week. Increases in cell density and proliferation coincided with strong upwelling of nutrients. High toxicity was driven by silicate limitation of the dense bloom. This temporal shift in species composition mirrored the shift observed further north in the California Current System off Oregon and Washington. The broad scope of sampling and unique platform capabilities employed during these studies revealed important patterns in bloom formation and persistence for Pseudo-nitzschia. Results underscore the benefit of expanded biological observing capabilities and targeted sampling methods to capture more comprehensive spatial and temporal scales for studying and predicting future events.

    更新日期:2018-09-03
  • Morphology and toxicity of Pseudo-nitzschia species in the northern Benguela Upwelling System
    Harmful Algae (IF 4.138) Pub Date : 2018-05-03
    Deon C. Louw, Gregory J. Doucette, Nina Lundholm

    The Benguela upwelling system, considered the world’s most productive marine ecosystem, has a long record of potentially toxic diatoms belonging to the genus Pseudo-nitzschia. Species of Pseudo-nitzschia were reported as early as 1936 from the northern Benguela upwelling system (nBUS). For the current study, long-term phytoplankton monitoring data (2004–2011) for the Namibian coast were analysed to examine inshore and offshore temporal distribution of Pseudo-nitzschia species, their diversity and ultrastructure. The potentially toxigenic P. pungens and P. australis were the dominant inshore species, whereas offshore Pseudo-nitzschia showed a higher diversity that also included potentially toxic species. During a warming event, a community shift from P. pungens and P. australis dominance to P. fraudulenta and P. multiseries was documented in the central nBUS.A case study of a toxic event (August 2004) revealed that P. australis and P. pungens were present at multiple inshore and offshore stations, coincident with fish (pilchard) and bird mortalities reported from the central part of Namibia. Toxin analyses (LC–MS/MS) of samples collected from June to August 2004 revealed the presence of particulate domoic acid (DA) in seawater at multiple stations (maximum ∼180 ng DA/L) in the >0.45 μm size-fraction, as well as detectable DA (0.12 μg DA/g) in the gut of one of two pilchard samples tested. These findings indicate that DA may have been associated with the fish and bird mortalities reported from this event in the nBUS. However, the co-occurrence of very high biomass phytoplankton blooms suggests that other explanations may be possible.

    更新日期:2018-05-03
  • Exploring dinoflagellate biology with high-throughput proteomics
    Harmful Algae (IF 4.138) Pub Date : 2018-04-16
    David Morse, Sirius P.K Tse, Samuel C.L. Lo

    Dinoflagellates are notorious for their ability to form the harmful algal blooms known as “red tides,” yet the mechanisms underlying bloom formation remain poorly understood. Despite recent advances in nucleic acid sequencing, which have generated transcriptomes from a wide range of species exposed to a variety of different conditions, measuring changes in RNA levels have not generally produced great insight into dinoflagellate cell biology or environmental physiology, nor do we have a thorough grasp on the molecular events underpinning bloom formation. Not only is the transcriptomic response of dinoflagellates to environmental change generally muted, but there is a markedly low degree of congruency between mRNA expression and protein expression in dinoflagellates. Herein we discuss the application of high-throughput proteomics to the study of dinoflagellate biology. By profiling the cellular protein complement (the proteome) instead of mRNA (the transcriptome), the biomolecular events that underlie the changes of phenotypes can be more readily evaluated, as proteins directly determine the structure and the function of the cell. Recent advances in proteomics have seen this technique become a high-throughput method that is now able to provide a perspective different from the more commonly employed nucleic acid sequencing. We suggest that the time is ripe to exploit these new technologies in addressing the many mysteries of dinoflagellate biology, such as how the symbiotic dinoflagellate inhabiting reef corals acclimate to increases in temperature, as well as how harmful algal blooms are initiated at the sub-cellular level. Furthermore, as dinoflagellates are not the only eukaryotes that demonstrate muted transcriptional responses, the techniques addressed within this review are amenable to a wide array of organisms.

    更新日期:2018-05-02
  • Circadian and irradiance effects on expression of antenna protein genes and pigment contents in dinoflagellate Prorocentrum donghaiense (Dinophycae)
    Harmful Algae (IF 4.138) Pub Date : 2018-04-16
    Xinguo Shi, Ling Li, Senjie Lin

    PCP and acpPC are the two major antennae proteins that bind pigments in peridinin-containing dinoflagellates. The relationship between antennae proteins and cellular pigments at molecular level is still poorly understood. Here we identified and characterized the two antennae protein genes in dinoflagellate Prorocentrum donghaiense under different light conditions. The mature PCP protein was 32 kDa, while acpPC was a polyprotein each of 19 kDa. Both genes showed higher expression under low light than under high light, suggesting their possible role in a low light adaptation mechanism. The two genes showed differential diel expression rhythm, with PCP being more highly expressed in the dark than in the light period and acpPC the other way around. HPLC analysis of cellular pigments indicated a diel change of chlorophyll c2, but invariability of other pigments. A stable peridinin: chlorophyll a pigment ratio was detected under different light intensities and over the diel cycle, although the diadinoxanthin:chlorophyll a ratio increased significantly with light intensity. The results suggest that 1) PCP and acpPC genes are functionally distinct, 2) PCP and acpPC can function under low light as an adaptive mechanism in P. donghaiense, 3). the ratios of diadinoxanthin:chlorophyll a and peridinin: chlorophyll a can potentially be used as an indicator of algal photophysiological status and a pigment signature respectively under different light conditions in P. donghaiense.

    更新日期:2018-05-02
  • Allelopathic interactions between the benthic toxic dinoflagellate Ostreopsis cf. ovata and a co-occurring diatom
    Harmful Algae (IF 4.138) Pub Date : 2018-04-16
    Eva Ternon, Anne-Sophie Pavaux, Sophie Marro, Olivier P. Thomas, Rodolphe Lemée

    For decades the microphytobenthos assemblage in the coastal Mediterranean Sea has been regularly colonized by the toxic benthic dinoflagellate Ostreopsis cf. ovata. This harmful algal species is a toxin producer and occupies the same ecological niche as various diatoms. Surprisingly, there are only few insights reported on the physiological responses of diatoms to blooms of O. cf. ovata The chemical interactions of O. cf. ovata with the co-occurring diatom Licmophora paradoxa was studied using a bioassay (measuring impact of cell-free culture filtrate) and a co-culture approach (separate by a membrane) to investigate the effects of the exometabolome and its mode of action. Bioassays highlighted a toxic effect of the exometabolome of O. cf. ovata on the diatom photosynthetic activity. However, the co-cultures revealed that these toxic effects do not occur through remote allelopathy. Contact or close interactions between cells of the two species is most likely needed to impair the diatom growth. Ovatoxins are suspected to be the toxic metabolites secreted by O. cf. ovata although the current set of data did not give confirmation of this assumption. Interestingly, the exometabolome of L. paradoxa impaired the growth and the photochemistry of O. cf. ovata in both bioassays and co-cultures. Some biomarkers possibly involved for the effect were identified using a metabolomic approach and may correspond to oxylipins, however a bacterial source of the bioactive metabolites is also considered.

    更新日期:2018-05-02
  • Identification, growth and toxicity assessment of Coolia Meunier (Dinophyceae) from Nova Scotia, Canada
    Harmful Algae (IF 4.138) Pub Date : 2018-04-27
    Nancy I. Lewis, Jennifer L. Wolny, John Claude Achenbach, Lee Ellis, Joseph S. Pitula, Cheryl Rafuse, Detbra S. Rosales, Pearse McCarron

    Benthic dinoflagellates of the toxigenic genus Coolia Meunier (Dinophyceae) are known to have a global distribution in both tropical and temperate waters. The type species, C. monotis, has been reported from the Mediterranean Sea, the NE Atlantic and from Rhode Island, USA in the NW Atlantic, whereas other species in the genus have been reported from tropical locations. Coolia cells were observed in algal drift samples collected at seven sites in Nova Scotia, Canada. Clonal isolates were established from four of these locations and identified with light and scanning electron microscopy, then confirmed with genetic sequencing to be C. monotis. This is the first record of this species in Nova Scotia. The isolates were established and incubated at 18 °C under a 14:10 L:D photoperiod with an approximate photon flux density of 50–60 μmol m−2 s−1. Growth experiments using an isolate from Johnston Harbour (CMJH) were carried out at temperatures ranging from 5 to 30 °C under the same photoperiod with an approximate photon flux density of 45–50 μmol m−2 s−1. Cells tolerated temperatures from 5 to 25 °C with optimum growth and mucilage aggregate production between 15 and 20 °C. Methanol extracts of this isolate examined by Liquid Chromatography-Mass Spectrometry (LC–MS) did not show the presence of the previously reported cooliatoxin. Toxic effects were assayed using two zebrafish bioassays, the Fish Embryo Toxicity (FET) assay and the General Behaviour and Toxicity (GBT) assay. The results of this study demonstrate a lack of toxicity in C. monotis from Nova Scotia, as has been reported for other genetically-confirmed isolates of this species. Conditions in which cell growth that could potentially degrade water quality and provide substrate and dispersal mechanisms for other harmful microorganisms via mucilage production are indicated.

    更新日期:2018-05-02
  • Imbalanced nutrient regimes increase Prymnesium parvum resilience to herbicide exposure
    Harmful Algae (IF 4.138) Pub Date : 2018-04-17
    Stacie L. Flood, JoAnn M. Burkholder

    The toxigenic haptophyte Prymnesium parvum is a mixotrophic phytoplankter with an extensive historic record of forming nearly monospecific, high-biomass, ecosystem-disrupting blooms, and it has been responsible for major fish kills in brackish waters and aquaculture facilities in many regions of the world. Little is known about how this species responds to commonly occurring environmental contaminants, or how nutrient (nitrogen, phosphorus) pollution may interact with environmentally relevant pesticide exposures to affect this harmful algal species. Here, standard algal toxicity bioassays from pesticide hazard assessments were used along with modified erythrocyte lysis assays to evaluate how atrazine exposures, imbalanced nutrient supplies, and salinity interact to influence the growth and toxicity in P. parvum isolates from three different regions. In nutrient-replete media, P. parvum 96 h IC50s ranged from 73.0 to 88.3 μg atrazine L−1 at salinity 10 and from 118 to >200 μg atrazine μg L−1 at salinity 20, and the response depended on the strain and the test duration. Relative hemolytic activity, used as an indication of toxicity, was a function of herbicide exposure, nutrient availability, salinity, geographic origin, and interactions among these factors. Highest levels of hemolytic activity were measured from a South Carolina strain in low-nitrogen media with high atrazine concentrations. Herbicide concentration was related to relative hemolytic activity, although a consistent relationship between growth phase and toxicity was not observed. Overall, these findings suggest that increasing chemical contamination is helping to promote ecosystem-disruptive, strongly mixotrophic algal blooms.

    更新日期:2018-05-02
  • What are the main environmental factors driving the development of the neurotoxic dinoflagellate Vulcanodinium rugosum in a Mediterranean ecosystem (Ingril lagoon, France)?
    Harmful Algae (IF 4.138) Pub Date : 2018-04-24
    Eric Abadie, Claude Chiantella, Anaïs Crottier, Lesley Rhodes, Estelle Masseret, Tom Berteaux, Mohamed Laabir

    Vulcanodinium rugosum, a dinoflagellate developing in Ingril Lagoon (Mediterranean, France) is responsible for shellfish intoxications due to the neurotoxin pinnatoxin G. A one year survey (March 2012–April 2013) was conducted in this oligotrophic shallow lagoon and key environmental parameters were recorded (temperature, salinity and nutrients). The spatio-temporal distribution of V. rugosum in water column and on macrophytes was also determined. Planktonic cells of V. rugosum were observed at all sampling stations, but in relatively low concentrations (maximum of 1000 cell/L). The highest abundances were observed from June to September 2012. There was a positive correlation between cell densities and both temperature and salinity. Non-motile cells were detected on macrophytes, with a maximum concentration of 6300 cells/g wet weight. Nitrite and ammonium were negatively related to V. rugosum abundance whereas total nitrogen, total phosphorus and phosphates showed a positive correlation. Altogether, in situ results suggest that V. rugosum is rather thermophilic and that organic nutrients should be considered when studying the nutrition requirements for this noxious expanding dinoflagellate.

    更新日期:2018-05-02
  • The highly heterogeneous methylated genomes and diverse restriction-modification systems of bloom-forming Microcystis
    Harmful Algae (IF 4.138) Pub Date : 2018-04-26
    Liang Zhao, Yulong Song, Lin Li, Nanqin Gan, Jerry J. Brand, Lirong Song
    更新日期:2018-05-02
  • A novel portable filtration system for sampling and concentration of microorganisms: Demonstration on marine microalgae with subsequent quantification using IC-NASBA
    Harmful Algae (IF 4.138) Pub Date : 2018-04-25
    Christos-Moritz Loukas, Matthew C. Mowlem, Maria-Nefeli Tsaloglou, Nicolas G. Green
    更新日期:2018-05-02
  • Phylogeny, morphology and toxicity of benthic dinoflagellates of the genus Fukuyoa (Goniodomataceae, Dinophyceae) from a subtropical reef ecosystem in the South China Sea
    Harmful Algae (IF 4.138) Pub Date : 2018-04-17
    Priscilla T.Y. Leung, Meng Yan, Veronica T.T. Lam, Sam K.F. Yiu, Chia-Yun Chen, J. Sam Murray, D. Tim Harwood, Lesley L. Rhodes, Paul K.S. Lam, Tak-Cheung Wai

    Species of Fukuyoa, recently revised from the globular Gambierdiscus, are toxic benthic dinoflagellates associated with ciguatera. In this study, a total of ten strains of Fukuyoa collected from Hong Kong waters were characterized using morphological and phylogenetic analyses. Results from both analyses showed that one of the strains is a putative new species, namely Fukuyoa sp. HK Type 1 (plate formula Po, 3′, 7″, 6c, 7s, 5‴, 1p and 2′‴ with a distinctive small and narrow cell shape, narrow Po plate, high Po pore density, large and broad Plate 1′ but small and round Po pore size, small and narrow Plate 2′, long and narrow Plates 2′‴ and 1p), and the others were F. ruetzleri. This is the first report of these two species of Fukuyoa in the South China Sea and Asia-Pacific region. Phylogenies on 18S, 28S D1/D3 and D8/D10 ribosomal DNA sequences strongly support that Fukuyoa sp. HK Type 1 is currently the most divergent species in the genus Fukuyoa. The diagrammatic plots on the p-distance matrices of 18S, 28S D1/D3 and D8/D10 and ITS regions resolved that the species of Fukuyoa were separated into three main groups, i.e., Fukuyoa sp. HK Type 1, F. paulensis and a group consisting of F. ruetzleri, F. yasumotoi and F. cf. yasumotoi, while Fukuyoa sp. HK Type 1 was always the most distant from the other two groups. Additionally, the pairwise p-distance values calculated based on the ITS region have always been the highest for pairs between Fukuyoa sp. HK Type 1 and other Fukuyoa species, ranging from 0.142 to 0.150. Our molecular results suggested that Fukuyoa sp. HK Type 1 is a putative new species. Both morphological and molecular data of more strains from different localities should be, however, collected to address its intraspecific variability and further evaluate its taxonomic status. A bioassay analysis demonstrated that algal lysates extracted from F. ruetzleri and Fukuyoa sp. HK Type 1 were lethal to brine shrimp larvae, indicating that both species were toxic. Bulk cultures were tested for Pacific ciguatoxins (P-CTXs) and maitotoxins (MTXs) by liquid chromatography-tandem mass spectrometry (LC–MS/MS). All isolates of Fukuyoa produced neither P-CTXs nor MTX-1, but isolates of F. ruetzleri produced a compound putatively assigned as MTX-3. This study has updated the current biodiversity and distribution of the toxic benthic dinoflagellates Fukuyoa, and thus contributes to the understanding of their emerging threats to the sub-tropical reef systems locally and regionally.

    更新日期:2018-05-02
  • Survival of cyanobacteria in rivers following their release in water from large headwater reservoirs
    Harmful Algae (IF 4.138) Pub Date : 2018-04-13
    Nicholas Williamson, Tsuyoshi Kobayashi, David Outhet, Lee C. Bowling

    Cyanobacterial survival following their release in water from major headwaters reservoirs was compared in five New South Wales rivers. Under low flow conditions, cyanobacterial presence disappeared rapidly with distance downstream in the Cudgegong and Hunter Rivers, whereas the other three rivers were contaminated for at least 300 km. Cyanobacterial survival is likely to be impacted by the geomorphology of each river, especially the extent of gravel riffle reaches (cells striking rocks can destroy them) and by the different turbulent flow conditions it produces within each. Flow conditions at gauging stations were used to estimate the turbulent strain rate experienced by suspended cyanobacteria. These indicate average turbulent strain rates in the Cudgegong and Hunter Rivers can be above 33 and 83 s−1 while for the Murray, Edward and Macquarie Rivers average strain rate was estimated to be less than 30 s−1. These turbulent strain rate estimates are substantially above published thresholds of approximately 2 s−1 for impacts indicated from laboratory tests. Estimates of strain rate were correlated with changes in cyanobacterial biovolume at stations along the rivers. These measurements indicate a weak but significant negative linear relationship between average strain rate and change in cyanobacterial biomass. River management often involves releasing cold deep water with low cyanobacterial presence from these reservoirs, leading to ecological impacts from cold water pollution downstream. The pollution may be avoided if cyanobacteria die off rapidly downstream of the reservoir, allowing surface water to be released instead. However high concentrations of soluble cyanotoxins may remain even after the cyanobacterial cells have been destroyed. The geomorphology of the river (length of riffle reaches) is an important consideration for river management during cyanobacterial blooms in headwater reservoirs.

    更新日期:2018-04-25
  • Variations of dominant free-floating Ulva species in the source area for the world’s largest macroalgal blooms, China: Differences of ecological tolerance
    Harmful Algae (IF 4.138) Pub Date : 2018-04-13
    Shiying Wang, Yuanzi Huo, Jianheng Zhang, Jianjun Cui, Yi Wang, Lili Yang, Qiaoyun Zhou, Yuwei Lu, Kefeng Yu, Peimin He

    Species composition and seasonal variations of free-floating Ulva species were investigated in the source area of the world’s largest macroalgal blooms during 2009–2015. Based on a combination of a morphological analysis and sequences of nuclear-encoded ITS and 5S rDNA spacer regions, the dominant species in the free-floating Ulva community at the early stage of green tides were Ulva compressa, Ulva flexuosa, and Ulva linza. The first appearance of Ulva prolifera on the sea surface was in mid-May and it dominated the floating Ulva community in June from 2009 to 2011. From 2012–2015, U. prolifera was not only the first species to appear on the sea surface but also the dominant species during the whole early stage of green tides. To explain the successional mechanism, the effects of environmental factors on the growth of four Ulva species were examined in the laboratory under different combinations of light intensity and temperature. It was found that the highest growth rate of U. prolifera was 44.9%/d, which was much higher than the other three Ulva species. The strong tolerance of U. prolifera to extreme conditions also helps it survive and bloom in the Yellow Sea.

    更新日期:2018-04-25
  • Succession and toxicity of Microcystis and Anabaena (Dolichospermum) blooms are controlled by nutrient-dependent allelopathic interactions
    Harmful Algae (IF 4.138) Pub Date : 2018-04-13
    Mathias A. Chia, Jennifer G. Jankowiak, Benjamin J. Kramer, Jennifer A. Goleski, I-Shuo Huang, Paul V. Zimba, Maria do Carmo Bittencourt-Oliveira, Christopher J. Gobler
    更新日期:2018-04-25
  • Characterization of oceanic Noctiluca blooms not associated with hypoxia in the Northeastern Arabian Sea
    Harmful Algae (IF 4.138) Pub Date : 2018-04-11
    Aneesh A. Lotliker, S.K. Baliarsingh, Vera L. Trainer, Mark L. Wells, Cara Wilson, T.V.S. Udaya Bhaskar, Alakes Samanta, S.R. Shahimol
    更新日期:2018-04-17
  • Feeding by the heterotrophic nanoflagellate Katablepharis remigera on algal prey and its nationwide distribution in Korea
    Harmful Algae (IF 4.138) Pub Date : 2018-04-12
    Jin Hee Ok, Hae Jin Jeong, An Suk Lim, Sung Yeon Lee, So Jin Kim

    Heterotrophic nanoflagellates are ubiquitous in natural waters, and most heterotrophic nanoflagellates are known to grow on bacteria. Recently, the heterotrophic nanoflagellate Katablepharis japonica has been reported to be an effective predator of diverse toxic or harmful algal prey. To date, 7 Katablepharis species have been identified, and therefore important questions arise as to whether other Katablepharis species can feed on algal prey, and further whether the types of prey of other Katablepharis species differ from those of K. japonica. To answer these important questions, feeding by Katablepharis remigera on diverse algal prey was examined. Specific growth and ingestion rates of K. remigera feeding on the raphidophytes Heterosigma akashiwo and Chattonella subsalsa were determined. Furthermore, the abundance of K. remigera at 28 stations along the coastline of Korea from January 2015 to October 2017 was quantified using qPCR method and newly designed specific primer-probe sets. Among 25 potential algal prey tested, K. remigera fed on only H. akashiwo and C. subsalsa; however, it did not feed on a diatom, a prymnesiophyte, a prasinophyte, cryptophytes, dinoflagellates, Mesodinium rubrum, a mixotrophic ciliate, and another raphidophyte Fibrocapsa japonica. The number of prey types on which K. remigera could feed (2 species) was considerably smaller than that of K. japonica (14 species). With the increase in the mean prey concentration, the specific growth rates of K. remigera on H. akashiwo and C. subsalsa increased as well before becoming saturated. The maximum specific growth rates of K. remigera on H. akashiwo and C. subsalsa were 0.717 and 0.129 d−1, respectively. In addition, the maximum ingestion rates of K. remigera on H. akashiwo and C. subsalsa were 0.333 and 0.661 ng C predator−1 d−1 (3.33 and 0.23 cells predator−1 d−1), respectively. The results of this study clearly indicate that K. remigera is an effective predator of 2 red tide-causing raphidophyte species, and additionally, the feeding activity of K. remigera differs greatly from that of K. japonica. The abundance of K. remigera was ≥0.1 cells mL−1 at 24 stations located in the East, West, and South Sea of Korea. Thus, K. remigera has a nationwide distribution in Korea. The highest abundance of K. remigera in Korean waters was 24.9 cells mL−1 in March 2017, when there was no red tide caused by H. akashiwo or Chattonella spp. In most regions where red tides caused by H. akashiwo or Chattonella spp. occurred in 2000–2017, K. remigera was detected. Thus, the abundance of K. remigera may increase during red tides caused by H. akashiwo and Chattonella spp.

    更新日期:2018-04-17
  • Feeding by the harmful phototrophic dinoflagellate Takayama tasmanica (Family Kareniaceae)
    Harmful Algae (IF 4.138) Pub Date : 2018-04-06
    An Suk Lim, Hae Jin Jeong, Jin Hee Ok, So Jin Kim

    The trophic mode of a phototrophic dinoflagellate is a critical factor in the dynamics of its harmful algal bloom. Recent discoveries of the mixotrophic capabilities of phototrophic dinoflagellates have changed the traditional view of bloom dynamics and prediction models. Here, mixotrophy in the harmful phototrophic dinoflagellate Takayama tasmanica was examined. Moreover, growth and ingestion rates of T. tasmanica on each of Alexandrium minutum CCMP1888 and Alexandrium tamarense CCMP1493, suitable prey, were determined as a function of prey concentration. This study reported for the first time that T. tasmanica is a mixotrophic species. Among the phytoplankton species offered as prey, T. tasmanica fed on all prey species whose equivalent spherical diameter (ESD) was greater than 30 μm, but also A. minutum whose ESD was 19 μm. In contrast, T. tasmanica did not feed on the phototrophic dinoflagellates Heterocapsa triquetra, Gymnodinium aureolum, Scrippsiella acuminata (previously S. trochoidea), Cochlodinium polykrikoides, Alexandrium affine, Alexandrium insuetum, and Alexandrium pacificum that its sister species Takayama helix is able to feed on. With increasing mean prey concentration, ingestion rates of T. tasmanica on A. minutum increased, but became saturated at the prey concentrations of >2130 cells mL−1 (1070 ng C mL−1). The maximum ingestion rate (MIR) of T. tasmanica on A. minutum was 0.5 ng C predator−1 d−1 (1.0 cells predator−1 d−1) which is only 64% of the body carbon of a T. tasmanica cell. Growth rates of T. tasmanica on A. minutum were not affected by prey concentrations. Thus, the low maximum ingestion rate is likely to be responsible for the small increases of its growth rate through mixotrophy. In addition, neither growth nor ingestion rates of T. tasmanica feeding on Alexandrium tamarense were affected by prey concentrations. The maximum ingestion rate of T. tasmanica on A. minutum was considerably lower than that of T. helix on the same prey species. Therefore, the mixotrophic ability of T. tasmanica is weaker than that of T. helix, and also T. tasmanica may have an ecological niche different from that of T. helix in marine ecosystems.

    更新日期:2018-04-07
Some contents have been Reproduced with permission of the American Chemical Society.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
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华中师范大学化学生物学中心招聘化学类博士后
哈尔滨工业大学刘绍琴教授课题组诚招博士后、科研助理
南方科技大学讲座教授郑智平团队——行政秘书招聘启事
南开化学40万年薪全年诚聘助理研究员(博士后)
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