Toxicity of Alexandrium lusitanicum to gastropod larvae is not caused by paralytic-shellfish-poisoning toxins

Publication Type  Journal Article
Year of Publication  2008
Authors  Juhl, A. R.; Martins, C. A.; Anderson, D. M.
Journal Title  Harmful Algae
Volume  7
Issue  5
Pages  567-573
Journal Date  Aug
ISBN Number  1568-9883
Accession Number  ISI:000257256300002
Key Words  allelopathy; grazing; nassarius; psp; red tide; saxitoxin; veliger; copepod acartia-clausi; tintinnid ciliate; feeding-behavior; chemical defense; united-states; algal blooms; dinoflagellate; growth; zooplankton; dynamics

Laboratory grazing experiments compared ingestion of two subclones of the dinoflagellate Alexandrium lusitanicum by gastropod veliger larvae (Nassarius sp.). While the two prey subclones originated from the same monoclonal isolate of A. lusitanicum, one possessed the ability to produce paralytic-shellfish-poisoning toxins (PSTs), while the other did not. Ingestion rates on the two Alexandrium subclones were not significantly different over a range of prey concentrations (approximately 100-660 cells ml(-1)), indicating that PSTs did not serve as a grazing deterrent for these larvae. However, ingestion rates on both subclones were low at the higher prey concentrations tested. Mortality of the predators also increased linearly with concentration of either subclone. These observations indicated that both A. lusitanicum subclones produced an unknown substance that inhibited and killed the grazers. Veliger mortality was not induced by culture filtrates or lysates, suggesting either that the substance was either highly labile or that contact with intact cells was required. Because toxic algae can produce multiple bioactive substances, experimental demonstrations of alleopathic effects of toxic species should not be assigned to known toxins without supporting evidence. In addition, the results show that the effectiveness of algal grazing deterrents can increase with cell concentration, which may have implications for bloom dynamics. (c) 2008 Elsevier B.V. All rights reserved.


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URL  <Go to ISI>://000257256300002
DOI  DOI 10.1016/j.hal.2007.12.019