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  • 2020-2023  (1)
  • 1995-1999  (2)
  • 1
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The planktonic copepod Calanus finmarchicus is a dominant member of the zooplankton community in the lower St. Lawrence Estuary in eastern Canada. Blooms of the toxic marine dinoflagellate Alexandrium excavatum which produces high cellular levels of paralytic shellfish poisoning (PSP) toxins, occur during the period of high C. finmarchicus production in summer in this region. To study the feeding behaviour of C. finmarchicus in the presence of Alexandrium spp., experiments were conducted in which female adult copepods collected from the St. Lawrence Estuary between May and September 1991 were exposed under controlled conditions to two toxic isolates of A. excavatum (Pr18b and Pr11f) from the estuary and to a non-toxic control (PLY 173) of a closely related species, A. tamarense isolated from the Tamar Estuary, Plymouth, U.K. Clearance rates on non-toxic A. tamarense cells averaged 5.5 ml ind-1 h-1 but were nearzero with either toxic isolate. When presented with a mixture of A. excavatum and the non-toxic diatom Thalassiosira weissflogii in varying proportions, C. finmarchicus fed upon the diatom but avoided the toxic dinoflagellate. Although feeding rates on A. excavatum were very low, toxin analysis by high-performance liquid chromatography with fluorescence detection (HPLC-FD) revealed that the PSP toxins were accumulated in copepods exposed to toxigenic dinoflagellates. The toxin composition in copepods was similar to that of the toxic dinoflagellate, but not necessarily identical, particularly after short-term (2-h) exposure, when relatively elevated levels of N-sulfocarbamoyl toxins were detected. The evidence suggests that C. finmarchicus ingests toxic dinoflagellate cells, either mistakenly or during exploratory bouts of feeding, and accumulates PSP toxins in its gut system and perhaps in other tissues.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Marine biology 134 (1999), S. 541-549 
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Profiles of diarrhetic shellfish poisoning (DSP) toxins produced throughout the growth cycle and the cell cycle of the toxigenic marine dinoflagellate Prorocentrum lima were studied in triplicate unialgal batch cultures. Cells were pre-conditioned at 18 ± 1 °C, under a photon flux density (PFD) of 90 ± 5 μmol m−2 s−1 on a 14 h light:10 h dark photoperiod. In exponential growth phase, cultures were synchronized in darkness for 17 d. After dark synchronization, cultures were transferred back to the original photoperiod regime. Cells were harvested for DSP toxin analysis by LC-MS (liquid chromatography with mass spectrometry), and double-stranded (nuclear) DNA was quantified by flow cytometry. The cell populations became asynchronous within approximately 3 d after transition from darkness to the 14 h light:10 h dark photoperiod. This may be due to the prolonged division cycle (5 to 7 d) that is not tightly phased by the photoperiod. Unlike other planktonic Prorocentrum spp., cytokinesis in P. lima occurred early in the dark and ceased by “midnight”. Cellular levels of the four principal DSP toxins, okadaic acid (OA), OA C8-diol-ester (OA-D8), dinophysistoxin-1 (DTX1) and dinophysistoxin-4 (DTX4), ranged from 0.37 to 6.6, 0.02 to 1.5, 0.04 to 2.6, and 1.8 to 7.8 fmol cell−1, respectively. No toxin production was evident during the extended period of dark synchronization nor during the initial period when NH4 was consumed as the major nitrogen source. Soon after the cells were returned to the 14 h light:10 h dark cycle and they began to take up NO3, cellular levels of all four toxins gradually increased. This increase in DSP toxins usually occurred in the light, marked by a rise in DTX4 levels that preceded an increase in the cellular concentration of OA and DTX1 (delayed by 3 to 6 h). Thus, DTX4 synthesis is initiated in the G1 phase of the cell cycle and persists into S phase (“morning” of the photoperiod), whereas OA and DTX1 production occurs later during S and G2 phases (“afternoon”). No toxin production was measured during cytokinesis, which happened early in the dark. The evidence indicates that toxin synthesis is restricted to the light period and is coupled to cell cycle events.
    Type of Medium: Electronic Resource
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  • 3
    Publication Date: 2022-09-21
    Description: • Harmful Algal Blooms (HABs) result from noxious and/or toxic algae that cause direct and indirect negative impacts to aquatic ecosystems, coastal resources, and human health. • HABs are present in nearly all aquatic environments (freshwater, brackish and marine), as naturally occurring phenomena. • Many HABs are increasing in severity and frequency, and biogeographical range. Causes are complex, but in some cases can be attributed to climate change and human impacts, including eutrophication, habitat modification, and human- mediated introduction of exogenous species. • There is no plan, and nor realistic possibility, to eliminate HABs and/or their depend-ent consequences. Decades of research and monitoring have, however, improved our understanding of HAB events, leading to better monitoring and prediction strate-gies. • HABs are a worldwide phenomenon requiring an international understanding leading ultimately to local and regional solutions. Continued progress in research, management, mitigation, and prediction of HABs benefits from international coordination. In this spirit, the international community has developed programmes sponsored by the Intergovernmental Oceanographic Commission (IOC) and Scientific Committee on Oceanic Research (SCOR) to coordinate international HAB research, framework activities, and capacity building. • HABs are recognized as one facet of complex ecosystem interactions with human society. HAB research, monitoring, and management must be closely integrated with policy decisions that affect our global oceans. • New initiatives, such as GlobalHAB sponsored by IOC and SCOR, will continue to provide the mechanisms to further understand, predict, and mitigate HABs. Research, management, and mitigation efforts directed towards HABs must be coordinated with other local, national, and international efforts focused on food and water security, human and ecosystem health, ocean observing systems, and climate change.
    Description: OPENASFA INPUT For bibliographic purposes this document should be cited as: R.M. Kudela et al. 2015. Harmful Algal Blooms. A Scientific Summary for Policy Makers. IOC/UNESCO, Paris (IOC/INF-1320).
    Description: Published
    Description: Non Refereed
    Keywords: HAB ; Harmful Algae Bloom ; Noxious algae ; Toxic algae ; Aquatic ecosystems ; Coastal resources ; Human health ; Climate Change ; Human impact ; Policy making ; Food security ; Water security
    Repository Name: AquaDocs
    Type: Report
    Format: 20pp.
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