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  • 1
    Electronic Resource
    Electronic Resource
    Interactions between Planktonic Microalgae and Protozoan Grazers (2004)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 51 (2004), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . For an algal bloom to develop, the growth rate of the bloom-forming species must exceed the sum of all loss processes. Among these loss processes, grazing is generally believed to be one of the more important factors. Based on numerous field studies, it is now recognized that microzooplankton are dominant consumers of phytoplankton in both open ocean and coastal waters. Heterotrophic protists, a major component of microzooplankton communities, constitute a vast complex of diverse feeding strategies and behavior which allow them access to even the larger phytoplankton species. A number of laboratory studies have shown the capability of different protistan species to feed and grow on bloom-forming algal species. Because of short generation times, their ability for fast reaction to short-term variation in food conditions enables phagotrophic protists to fulfill the function of a heterotrophic buffer, which might balance the flow of matter in case of phytoplankton blooms. The importance of grazing as a control of microalgae becomes most apparent by its failure; if community grazing controls initial stages of bloom development, there simply is no bloom. However, if a certain algal species is difficult to graze, e.g. due to specific defense mechanisms, reduced grazing pressure will certainly favor bloom development. The present contribution will provide a general overview on the interactions between planktonic microalgae and protozoan grazers with special emphasis on species-specific interactions and algal defense strategies against protozoan grazers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.2004.tb00540.x
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  • 2
    Electronic Resource
    Electronic Resource
    Distribution of carbon among photosynthetic end products in the bloom-forming arctic diatom Thalassiosira antarctica COMBER (1989)
    Springer
    Polar biology 10 (1989), S. 231-238 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Investigations of the bloom-forming arctic diatom Thalassiosira antarctica COMBER show that at all temperature and light conditions tested, the 14C-incorporation rates in lipids averaged 20% and in carbohydrates 12%. The percentage of 14C in proteins and small metabolites ranged from 30% to 50% respectively, with contrary trends. The production rate of protein per generation time was not temperature and light dependent. The changes in percent carbon incorporated into proteins may be due to enhanced metabolite synthesis at high irradiances and/or temperatures above 0° C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00238500
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  • 3
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    Azaspiracid variability of Azadinium poporum (Dinophyceae) from the China Sea (2014)
    ELSEVIER SCIENCE BV
    In:  EPIC3Harmful Algae, ELSEVIER SCIENCE BV, 36, pp. 22-28, ISSN: 1568-9883
    Details
    Publication Date: 2019-07-17
    Description: Azadinium poporum is a small dinoflagellate from the family Amphidomataceae which is known for the production potential of azaspiracids (AZAs) causative of azaspiracid shellfish poisoning (AZP). A. poporum has been recorded from European and western Pacific waters. Here we report on the high variability of toxin profiles within this species in Chinese coastal waters. Out of 16 analyzed strains of A. poporum from different geographic locations along the Chinese coastline, three strains proved not to contain AZAs, whereas 13 strains contained different combinations of AZA-2, AZA-11, AZA-37, a yet unknown isomer of AZA-1 (named AZA-40) and new AZA with yet unreported molecular mass of 853 Da (named AZA-41). The new AZA-40, other than AZA-1 itself, belongs to the recently discovered “348-type” group, which in tandem mass spectrometry displays a group 4 fragment with m/z 348 instead of the group 4 fragment of the classic AZAs with m/z 362, indicating a shift of a methyl group from the C24-C40 part of the molecule (rings F-I) to the C2-C9 part (carboxylic side chain and ring A). AZA-41 apparently is a dehydro variant of AZA-2. In addition a previously reported AZA with a molecular mass 871 DA could be unambiguously assigned to AZA-11, which is known to be a shellfish metabolite of AZA-2. This is the first report of AZA-11 being also de novo synthetized by dinoflagellates.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 4
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    Life cycle of the pseudocolonial dinoflagellate Polykrikos kofoidii (Gymnodiniales, Dinoflagellata) (2013)
    WILEY-BLACKWELL PUBLISHING
    In:  EPIC3Journal of Phycology, WILEY-BLACKWELL PUBLISHING, 49, pp. 298-317, ISSN: 0022-3646
    Details
    Publication Date: 2019-07-17
    Description: The athecate, pseudocolonial polykrikoid dinoflagellates show a greater morphological complexity than many other dinoflagellate cells and contain not only elaborate extrusomes but sulci, cinguli, flagellar pairs, and nuclei in multiple copies. Among polykrikoids, Polykrikos kofoidii is a common species that plays an important role as a grazer of toxic planktonic algae but whose life cycle is poorly known. In this study, the main life cycle stages of P. kofoidii were examined and documented for the first time. The formation of gametes, 2-zooid-1-nucleus stages very different from vegetative cells, was observed and the process of gamete fusion, isogamy, was recorded. Karyogamy followed shortly after completed plasmogamy. A complex reorganization of furrows (cinguli and sulci) and flagella followed zygote formation, resulting in a 4-zooid zygote with one nucleus. The fate of zygotes under different nutritional conditions was also investigated; well-fed zygotes were able to reenter the vegetative cycle via meiotic divisions as indicated by nuclear cyclosis. However, nuclear cyclosis was preceded by a presumably mitotic division of the primary zygote nucleus which by definition would imply that P. kofoidii has a diplohaplontic life cycle. Nuclear cyclosis in germlings hatched from spiny resting cysts indicate that these cysts are of zygote origin (hypnozygotes). Hypnozygote formation, cyst hatching, the morphology of the germling (a 1-zooid cell), and its development into a normal pseudocolony are documented here for the first time. There is evidence that P. kofoidii has a system of complex heterothallism.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 5
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    Dinoflagellaten – ein Dauerexperiment der Evolution? (2018)
    Wiley-VCH Verlag
    In:  EPIC3Biologie in unserer Zeit, Wiley-VCH Verlag, 48, pp. 228-238
    Details
    Publication Date: 2020-02-25
    Description: Dinoflagellaten haben nur eine oberflächliche Namensähnlichkeit mit den Dinosauriern (vom altgriechischen δεινός/ deinós = schrecklich); ihr Name leitet sich von dem altgriechischen δινος/dinos (wirbeln) ab und beschreibt die charakteristische Schwimmbewegung dieser mit dem bloßen Auge nicht direkt wahrnehmbaren Protisten. Die Bedeutung der sehr diversen und mit vielen faszinierenden Facetten aufwartenden Einzellergruppe ist nicht zu unterschätzen. So sind sie u. a. wichtige Produzenten und Konsumenten in aquatischen Nahrungsnetzen, Symbionten in Korallen, Parasiten mariner Organismen sowie dem Menschen gefährlich werdende Giftproduzenten. Auch morphologisch, biochemisch und genetisch besitzen Dinoflagellaten Besonderheiten, die sie zu einer der interessantesten eukaryotischen Gruppen machen.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 6
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    Distribution of Alexandrium fundyense (Dinophyceae) cysts in Greenland and Iceland, with an emphasis on viability and growth in the Arctic (2016)
    INTER-RESEARCH
    In:  EPIC3Marine Ecology-Progress Series, INTER-RESEARCH, 547, pp. 33-46, ISSN: 0171-8630
    Details
    Publication Date: 2019-07-17
    Description: The bloom-forming dinoflagellate Alexandrium fundyense has been extensively studied due its toxin-producing capabilities and consequent impacts on human health and eco - nomies. 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 A. fundyense 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 (16 h light:8 h dark) and higher irradiance levels (~146 to 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 A. fundyense 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.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 7
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    Revisiting the 1991 algal bloom in shelf waters off Argentina: Azadinium luciferelloides sp. nov. (Amphidomataceae, Dinophyceae) identified as the causative species in a diverse community of other amphidomataceans (2016)
    WILEY-BLACKWELL PUBLISHING
    In:  EPIC3Phycological Research, WILEY-BLACKWELL PUBLISHING, 64, pp. 160-175, ISSN: 1322-0829
    Details
    Publication Date: 2019-07-17
    Description: Amphidoma (Amphidomataceae) mostly attract attention because of their production potential of the lipophilic polyether phycotoxin azaspiracid (AZA). The genus Azadinium probably has a very wide geographical distribution. Blooms of Azadinium from the continental shelf off Argentina have been observed back in the early 1990, but were just recently published, and the causative species, identified at that time as Azadinium cf. spinosum, could not unequivocally be determined. Here we retrospectively analyzed old archived samples of one of the South Atlantic Azadinium bloom from 1991 with electron microscopy. It turned out that the dominant nanoplanktonic dinophycean species in fact represent a new species which we describe here based on the morphology. Azadinium luciferelloides sp. nov. is a small (approximately 9–14 μm cell length) thecate dinoflagellate with the dominant plate pattern of the genus (Po, X, 4´, 3a, 6´´ , 6C, 5S, 6´´´, 2´´´´), and with a small antapical spine. Azadinium luciferelloides differed from all other described species of Azadinium by the position of the ventral pore, which was located on the right ventral side in a notch of an otherwise symmetric pore plate. In addition, we recorded and documented the presence of other similar sized species of the Amphidomataceae in the samples. Our finding of Az. spinosum, Az. dalianense, Az. dexteroporum, and Amphidoma languida are the first record for the South Atlantic and thus describe an important range extension of these species. The diversity and importance of the Amphidomataceae for South Atlantic spring bloom plankton is now known and taxonomically documented, but cultures and/or analysis of AZA in field samples of the area are needed to clarify the AZA production potential of the local species and populations in order to finally evaluate the risk potential of AZA for AZA shellfish contamination in the Southwestern Atlantic region.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 8
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    Identification of Azadinium species and a new azaspiracid from Azadinium poporum in Puget Sound, Washington State, USA (2017)
    ELSEVIER SCIENCE BV
    In:  EPIC3Harmful Algae, ELSEVIER SCIENCE BV, 68, pp. 152-167, ISSN: 1568-9883
    Details
    Publication Date: 2019-07-17
    Description: The identification of a new suite of toxins, called azaspiracids (AZA), as the cause of human illnesses after the consumption of shellfish from the Irish west coast in 1995, resulted in interest in understanding the global distribution of these toxins and of species of the small dinoflagellate genus Azadinium, known to produce them. Clonal isolates of four species of Azadinium, A. poporum, A. cuneatum, A. obesum and A. dalianense were obtained from incubated sediment samples collected from Puget Sound, Washington State in 2016. These Azadinium species were identified using morphological characteristics confirmed by molecular phylogeny. Whereas AZA could not be detected in any strains of A. obesum, A. cuneatum and A. dalianense, all four strains of A. poporum produced a new azaspiracid toxin, based on LC–MS analysis, named AZA-59. The presence of AZA-59 was confirmed at low levels in situ using a solid phase resin deployed at several stations along the coastlines of Puget Sound. Using a combination of molecular methods for species detection and solid phase resin deployment to target shellfish monitoring of toxin at high-risk sites, the risk of azaspiracid shellfish poisoning can be minimized.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 9
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    Morphological, molecular, and toxin analysis of field populations of Alexandrium genus from the Argentine Sea (2017)
    WILEY-BLACKWELL PUBLISHING
    In:  EPIC3Journal of Phycology, WILEY-BLACKWELL PUBLISHING, 53(6), pp. 1206-1222, ISSN: 0022-3646
    Details
    Publication Date: 2019-07-16
    Description: In the Argentine Sea, blooms of toxigenic dinoflagellates of the Alexandrium tamarense species complex have led to fish and bird mortalities and human deaths as a consequence of paralytic shellfish poisoning (PSP). Yet little is known about the occurrence of other toxigenic species of the genus Alexandrium, or of their toxin composition beyond coastal waters. The distribution of Alexandrium species and related toxins in the Argentine Sea was determined by sampling surface waters on an oceanographic expedition during austral spring from ~39°S to 48°S. Light microscope and SEM analysis for species identification and enumeration was supplemented by confirmatory PCR analysis from field samples. The most frequent Alexandrium taxon identified by microscopy corresponded to the classical description of A. tamarense. Only weak signals of Group I from the A. tamarense species complex were detected by PCR of bulk field samples, but phylogenetic reconstruction of rDNA sequences from single cells from one station assigned them to ribotype Group I (Alexandrium catenella). PCR probes for Alexandrium minutum and Alexandrium ostenfeldii yielded a positive signal, although A. minutum morphology did not completely match the classical description. Analysis of PSP toxin composition of plankton samples revealed toxin profiles dominated by gonyautoxins (GTX1/4). The main toxic cyclic imine detected was 13-desMe-spirolide C and this supported the association with A. ostenfeldii in the field. This study represents the first integrated molecular, morphological and toxinological analysis of field populations of the genus Alexandrium in the Argentine Sea.
    Repository Name: EPIC Alfred Wegener Institut
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  • 10
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    A Gordian knot: Nomenclature and taxonomy of Heterocapsa triquetra (Peridiniales: Heterocapsaceae) (2018)
    International Association for Plant Taxonomy
    In:  EPIC3Taxon, International Association for Plant Taxonomy, 67(1), pp. 179-185, ISSN: ISSN 0040-0262
    Details
    Publication Date: 2019-04-05
    Description: In the course of polyphasic taxonomic work in the dinophytes, we became aware of a fundamental misapplication of the name Glenodinium triquetrum (now represented conceptually by a species of Kryptoperidinium), when Stein assigned it to Heterocapsa. Possible solutions involve a conflict between retaining Ehrenberg’s epithet in its correct application in the interest of priority and preserving current usage of Heterocapsa. However, we do not achieve a consensus on how to disentangle this Gordian knot, underlining that this is not a regular case of taxonomic confusion. We intend to stimulate a more general discussion about best practices in such cases, balancing between the interest of nomenclatural practicability and the respectful acknowledgement of scientific work, even if it was conducted many years ago.
    Repository Name: EPIC Alfred Wegener Institut
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