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  • 11
    Publication Date: 2019-07-17
    Description: A unialgal culture of a Pseudo-nitzschia species dominant in the plankton of Algoa Bay in the spring of 2012 was established by isolation of clonal chains of cells. Identification of the species as Pseudo-nitzschia multiseries was based on frustule morphometrics provided by light and scanning electron microscopy, and confirmed by phylogenetic analysis of the LSU rDNA gene. Cultures were shown to produce domoic acid (DA) as measured by ELISA and LC/MS-MS methods, and levels of cellular DA were ∼0.1 pg cell–1. Although it is recognised as a cosmopolitan species, these observations provide the first account of this toxic diatom in the coastal waters of South Africa.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 12
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    FAO
    In:  EPIC3Proceedings of the 9th International Conference on Molluscan Shellfish Safety, Sydney, 17-22 March 2013, ICMSS 2013 Twenty Years: Defining future shellfish safety frontiers through innovaton in science and policy: Proceeedings: 9th International Conference on Molluscan Shellfish Safety, Sydney, Australia, FAO, 249 p., pp. 111-113, ISBN: 978-0-646-92993-4
    Publication Date: 2015-02-13
    Description: Two oceanographic surveys for toxigenic phytoplankton in the South and North Atlantic Ocean, including the adjacent Irminger Sea and the Arctic coasts of Greenland and Iceland, were conducted for analysis of putative toxic microalgal species and their respective toxins. During both expeditions, plankton was sampled by phytoplankton net (20 μm mesh) vertical hauls with subsequent size-fractionation, and by filtration of Niskin bottle water samples from discrete depths. In addition, sediment samples at selected stations were taken for identification and analysis of organic-walled dinoflagellate cysts (dinocysts). Among the toxins detected in both areas were domoic acid (DA), pectenotoxins (PTXs), yessotoxin (YTX), and paralytic shellfish toxins (PSTs). In addition, in the northern hemisphere, dinophysistoxins (DTXs) and spirolides were present, but these toxins were not found in Argentinean waters. In the sediments of San Jorge Gulf of Argentina, cysts of the dinoflagellate species Alexandrium tamarense and Protoceratium reticulatum were found, and their respective toxins (PSTs and YTX) were associated with the planktonic samples from the same stations.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Inbook , peerRev
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  • 13
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    Academic Press
    In:  EPIC3Encyclopedia of Biodiversity, Second Edition V.1.1, Encyclopedia of Biodiversity, Second Edition V.1, Waltham, MA, Academic Press, pp. 470-484
    Publication Date: 2014-04-15
    Repository Name: EPIC Alfred Wegener Institut
    Type: Inbook , peerRev
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  • 14
    Publication Date: 2019-07-17
    Description: The public health, tourism, fisheries, and ecosystem impacts from harmful algal blooms (HABs) have all increased over the past few decades. This has led to heightened scientific and regulatory attention, and the development of many new technologies and approaches for research and management. This, in turn, is leading to significant paradigm shifts with regard to, e.g.,our interpretation of the phytoplankton species concept (strain variation), the dogma of their apparent cosmopolitanism, the role of bacteria and zooplankton grazing in HABs, and our approaches to investigating the ecological and genetic basis for the production of toxins and allelochemicals. Increasingly,eutrophication and climate change are viewed andmanaged as multifactorial environmental stressors that will further challenge managers of coastal resources and those responsible for protecting human health. Here we review HABscience with an eye toward new concepts and approaches,emphasizing, where possible, the unexpected yet promising new directions that research has taken in this diverse field.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 15
    Publication Date: 2018-12-13
    Description: The CoCliME project co-develops and co-produces bespoke, proof-of-concept or prototype marine ecosystem climate services and a transferable framework for climate services development, to support informed decision making relevant to climate change-related ecological and socio-economic impacts across different coastal regions. The consortium brings together a transdisciplinary team of natural- and social scientists, decision makers, and users of climate services that will dynamically interact to identify common priority climate change-related vulnerabilities and solutions in six European coastal areas. In these case studies from the North Atlantic Ocean and the Baltic-, Black-, Mediterranean-, North- and Norwegian Seas. CoCliME focuses on coastal ecosystem status indicators, e.g. harmful algal blooms, biotoxins, pathogens and microbial biodiversity, that can be markedly influenced by climate change and have direct impacts on human health, economic prosperity and social wellbeing. Available global IPCC climate change scenarios are selected and refined to adapt to the specific regional requirements of the case study area. Here we define the first project results of a hindcast data study, including preliminary analyses of the modelling component of the North Sea case study. In addition, we present a coordinated CoCliME sampling initiative to document the presence or absence of potential toxigenic representatives of the benthic dinoflagellate genera Ostreopsis, Gambierdiscus, Coolia and Prorocentrum at various sites of the case study areas
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
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  • 16
    Publication Date: 2019-01-16
    Description: Spirolides are polyether cyclic imines considered as “fast acting toxins.” Long-term human health consequences of spirolide ingestion are uncertain, and hence regulatory limits for human consumption have not been established. Nevertheless, monitoring these toxins in shellfish is essential because they can interfere with detection by mouse bioassay of lipophilic regulated toxins. Todos Santos Bay (TSB), in the northwest of the Baja California Peninsula, is an important shellfish cultivation and fish-farming area in Mexico. The toxin analog 13-desmethyl spirolide C has been reported in cultivated mussels (Mytilus galloprovincialis) from TSB, but the causative species associated with accumulation of this toxin has not been previously identified. We assessed the occurrence of Alexandrium ostenfeldii, the unique known producer of spirolides, by inverted light microscopy and by PCR with species-specific oligonucleotides designed for the ITS and 18S rDNA. We determined the presence and abundance of this species at the surface and at the thermocline from samples collected over two annual sampling periods (2013–2014 and 2016–2017). During the 2013–2014 period, A. ostenfeldii was found in 50% of the samples analyzed by light microscopy. The highest cell abundance occurred in October 2013. During 2016–2017 the dinoflagellate was present in low cell abundances and was detected in only 20.9% of the samples. Cells of this species were usually found when sea surface temperature ranged from 17 to 20 C. We also evaluated spirolide accumulated in cultivated mussels from TSB by tandem mass spectrometry (LC-MS/MS). The only spirolide detected was 13-desmethyl spirolide C, found mainly during the 2013–2014 sampling period, with the highest concentration in June 2014. During winter, toxin concentration was at or below the detection limit. During 2016–2017,spirolides were below the detection limit, coinciding with the absence of the causative species. Cell abundance of A. ostenfeldii and spirolide concentration in mussels did not present a clear correlation. This study represents the first record of A. ostenfeldii in TSB and provides evidence that this species is the primary origin of spirolides accumulated in mussels.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 17
    Publication Date: 2019-07-16
    Description: Arctic regions have experienced pronounced biological and biophysical transformations as a result of global change processes over the last several decades. Current hypotheses propose an elevated impact of those environmental changes on the biodiversity, community composition and metabolic processes of species. The effects on ecosystem function and services, particularly when invasive or toxigenic harmful species become dominant, can be expressed over a wide range of temporal and spatial scales in plankton communities. Our study focused on the comparison of molecular biodiversity of three size-fractions (micro-, nano-, picoplankton) in the coastal pelagic zone of West Greenland and their association with environmental parameters. Molecular diversity was assessed via parallel amplicon sequencing the 28S rRNA hypervariable D1/D2 region. We showed that biodiversity distribution within the area of Uummannaq Fjord, Vaigat Strait and Disko Bay differed markedly within and among size-fractions. In general, we observed a higher diversity within the picoplankton size fraction compared to the nano- and microplankton. In multidimensional scaling analysis, community composition of all three size fractions correlated with cell size, silicate and phosphate, chlorophyll a (chl a) and dinophysistoxin (DTX). Individually, each size fraction community composition also correlated with other different environmental parameters, i.e. temperature and nitrate. We observed a more homogeneous community of the picoplankton across all stations compared to the larger size classes, despite different prevailing environmental conditions of the sampling areas. This suggests that habitat niche occupation for larger-celled species may lead to higher functional trait plasticity expressed as an enhanced range of phenotypes, whereas smaller organisms may compensate for lower potential plasticity with higher diversity. The presence of recently identified toxigenic harmful algal bloom (HAB) species (such as Alexandrium fundyense and A. ostenfeldii) in the area points out the potential risk for this vulnerable ecosystem in a changing world.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 18
    Publication Date: 2022-05-25
    Description: Author Posting. © The Author(s), 2016. This is the author's version of the work. It is posted here by permission of Inter-Research for personal use, not for redistribution. The definitive version was published in Marine Ecology Progress Series 547 (2016): 33-46, doi:10.3354/meps11660.
    Description: The bloom-forming dinoflagellate Alexandrium fundyense has been extensively studied due its toxin-producing capabilities and consequent impacts to human health and economies. This study investigated the prevalence of resting cysts of A. fundyense in western Greenland and Iceland to assess the historical presence and magnitude of bloom populations in the region, and to characterize environmental conditions during summer, when bloom development may occur. Analysis of sediments collected from these locations showed that Alexandrium cysts were present at low to moderate densities in most areas surveyed, with highest densities observed in western Iceland. Additionally, laboratory experiments were conducted on clonal cultures established from isolated cysts or vegetative cells from Greenland, Iceland, and the Chukchi Sea (near Alaska) to examine the effects of photoperiod interval and irradiance levels on growth. Growth rates in response to the experimental treatments varied among isolates, but were generally highest under conditions that included both the shortest photoperiod interval (16h:8h light:dark) and higher irradiance levels (~146-366 µmol photons m-2 s-1), followed by growth under an extended photoperiod interval and low irradiance level (~37 µmol photons m-2 s-1). Based on field and laboratory data, we hypothesize that blooms in Greenland are primarily derived from advected Alexandrium populations, as low bottom temperatures and limited light availability would likely preclude in situ bloom development. In contrast, the bays and fjords in Iceland may provide more favorable habitat for germling cell survival and growth, and therefore may support indigenous, self-seeding blooms.
    Description: Funding for this study was provided by the James M. and Ruth P. Clark Arctic Research Initiative to Anderson and Richlen, and for the ARCHEMHAB expedition via the Helmholtz Institute initiative Earth and Environment under the PACES Program Topic 2 Coast (Workpackage 3) of the Alfred Wegener Institute. Additional support was provided by the Woods Hole Center for Oceans and Human Health through National Science Foundation (NSF) Grant OCE-1314642 and National Institute of Environmental Health Sciences (NIEHS) Grant 1-P01-ES021923-01.
    Description: 2017-04-07
    Keywords: Arctic ; Alexandrium ; Dinoflagellate ; Cysts ; Harmful algal bloom
    Repository Name: Woods Hole Open Access Server
    Type: Preprint
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  • 19
    Publication Date: 2019-07-17
    Description: Surfclams,Spisula solidissima, pose a particular health risk for human consumption as they are characterized by accumulation of extremely high levels of toxins associated with paralytic shellfish poisoning (PSP), slow toxin elimination and an extremely high post-ingestive capacity for toxin bioconversion. Surfclam populations experience a wide range of temperatures along the NW Atlantic continental shelf, and are undergoing range contraction that has been attributed to global warming. In this study the influence of temperature (5, 12 and 21 C) on detoxification kinetics of individual PSP toxins in two tissue compartments of juvenile surfclams (∼35 mm shell length) was determined under controlled laboratory conditions, over prolonged (2.4 months) depuration. Clams were toxified with a representative regional Gulf of Maine isolate of the dinoflagellate Alexandrium fundyense of known toxin profile, allowing tracking of changes in toxin composition and calculated toxicity in surfclam tissues. The visceral mass detoxified at all temperatures, although toxin loss rate increased with increasing temperature. In contrast, total toxin content and calculated toxicities in other tissues remained constant or even increased during depuration, suggesting a physiological or biochemical toxin-retention mechanism in this tissue pool and temperature-independent detoxification. In vivo toxin compositional changes in surfclam tissues found in this study provide evidence of specific toxin conversion pathways,involving both reductive and decarbamoylation pathways. We conclude that such toxin biotransformations, especially in non-visceral tissues, may introduce a discrepancy in describing kinetics of total toxicity (in saxitoxin equivalents [STXeq]) of S. solidissima over prolonged detoxification. Nevertheless, use of total toxicity values generated by routine regulatory monitoring based upon mouse bioassays or calculated from chemical analytical determination of molar toxin concentrations is adequate for first-order modeling of toxin kinetics in this species. Furthermore, the differential detoxification response of viscera and other tissues in relation to temperature emphasizes the need for two-compartment modeling to describe the fate of PSP toxins in this species. Finally, key parameters were identified that may prove useful in hindcasting the timing of toxic blooms or new toxin input in deep offshore waters where routine monitoring of toxic phytoplankton is impractical.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 20
    Publication Date: 2021-10-24
    Description: The marine dinoflagellate genus Prorocentrum Ehrenberg comprises many species occupying primarily benthic or epiphytic habitats, particularly in tropical and sub-tropical waters. Despite concerted efforts to establish phylogenetic associations, there remain unresolved issues in defining morphospecies and membership in species complexes. The study described herein addressed the inter- and infraspecific relationships of members of the Prorocentrum lima and Prorocentrum hoffmannianum species complexes (PLSC and PHSC, respectively) by applying multivariate approaches in morphotaxonomy, molecular phylogenetics and chemodiversity to establish affinities among multiple clonal isolates. Morphotaxonomic analysis showed consistency with classical morphospecies descriptors, and high variability in cell size and dimensions, but did not challenge current species complex concepts. Phylogenetic analysis of ITS/5.8S rDNA sequences from isolates from the Gulf of California, Caribbean Sea, and Gulf of Mexico coasts compared with archived global GenBank sequences served to define five consistent clades with separation of the PLSC and PHSC. Secondary structure modeling of ITS2 rRNA variation based on compensatory base changes (CBC) was effective in resolving details of the respective species complexes and even indicated putative incipient or cryptic speciation due to potential hybridization barriers. This study represents the largest (n = 67 isolates) chemodiversity analysis of polyketide-derived toxins associated with diarrheic shellfish poisoning (DSP) from a benthic dinoflagellate genus. Relative composition of some analogs (OA, OA-D8, DTX1, DTX1a, and DTX1a-D8), including two new undescribed isomers, distinguished P. lima from P. hoffmannianum sensu lato, but without clear associations with substrate type or geographical origin. Although all P. lima and most (one exception) P. hoffmannianum were toxigenic, the total cell toxin content could not be linked at the species level. This research demonstrates that clonal chemodiversity in toxin composition cannot yet be effectively applied to define ecological niches or species interactions within local assemblages. Phylogenetic analysis of the ITS/5.8 rDNA, particularly when combined with secondary structure modeling, rather than only a comparison of LSU rDNA sequences, is a more powerful approach to identify cryptic speciation and to resolve species complexes within benthic dinoflagellate groups.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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