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Pfiesteria shumwayae kills fish by micropredation not exotoxin secretion


Pfiesteria piscicida and P. shumwayae reportedly secrete potent exotoxins thought to cause fish lesion events, acute fish kills and human disease in mid-Atlantic USA estuaries1,2,3,4,5,6,7. However, Pfiesteria toxins have never been isolated or characterized8. We investigated mechanisms by which P. shumwayae kills fish using three different approaches. Here we show that larval fish bioassays conducted in tissue culture plates fitted with polycarbonate membrane inserts exhibited mortality (100%) only in treatments where fish and dinospores were in physical contact. No mortalities occurred in treatments where the membrane prevented contact between dinospores and fish. Using differential centrifugation and filtration of water from a fish-killing culture, we produced ‘dinoflagellate’, ‘bacteria’ and ‘cell-free’ fractions. Larval fish bioassays of these fractions resulted in mortalities (60–100% in less than 24 h) only in fractions containing live dinospores (‘whole water’, ‘dinoflagellate’), with no mortalities in ‘cell-free’ or ‘bacteria’-enriched fractions. Videomicrography and electron microscopy show dinospores swarming toward and attaching to skin, actively feeding, and rapidly denuding fish of epidermis. We show here that our cultures of actively fish-killing P. shumwayae do not secrete potent exotoxins; rather, fish mortality results from micropredatory feeding.

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Figure 1
Figure 2: Results from bioassays using larval Cyprinodon variegatus exposed in six-well tissue culture plates fitted with polycarbonate membrane inserts.
Figure 3: Fractionation assay with larval Fundulus heteroclitus using a Pfiesteria shumwayae culture that actively killed tilapia in a 38-l assay.
Figure 4: Myzocytosis by Pfiesteria shumwayae on the epidermis of larval Cyprinodon variegatus.


  1. Burkholder, J. M., Noga, E. J., Hobbs, C. H. & Glasgow, H. B. Jr New “phantom” dinoflagellate is the causative agent of major estuarine fish kills. Nature 358, 407–410 (1992)

    Article  ADS  CAS  Google Scholar 

  2. Burkholder, J. M., Glasgow, H. B. Jr & Hobbs, C. B. Fish kills linked to a toxic ambush-predator dinoflagellate: distribution and environmental conditions. Mar. Ecol. Prog. Ser. 124, 43–61 (1995)

    Article  ADS  Google Scholar 

  3. Glasgow, H. B. Jr, Burkholder, J. M., Schmechel, D. E., Tester, P. E. & Rublee, P. A. Insidious effects of a toxic estuarine dinoflagellate on fish survival and human health. J. Toxicol. Environ. Health 46, 501–522 (1995)

    Article  CAS  Google Scholar 

  4. Noga, E. J., Khoo, L., Stevens, J. B., Fan, Z. & Burkholder, J. M. Novel toxic dinoflagellate causes epidemic disease in estuarine fish. Mar. Pollut. Bull. 32, 219–224 (1996)

    Article  CAS  Google Scholar 

  5. Burkholder, J. M., Glasgow, H. B. Jr & Deamer-Melia, N. J. Overview and present status of the toxic Pfiesteria complex (Dinophyceae). Phycologia 40, 186–214 (2001)

    Article  Google Scholar 

  6. Grattan, L. M. et al. Learning and memory difficulties after environmental exposure to waterways containing toxin-producing Pfiesteria or Pfiesteria-like dinoflagellates. Lancet 352, 532–539 (1998)

    Article  CAS  Google Scholar 

  7. Grattan, L. M., Oldach, D. & Morris, G. Human health risks of exposure to Pfiesteria piscicida. Bioscience 51, 853–857 (2001)

    Article  Google Scholar 

  8. Moeller, P. D. et al. Current progress in isolation and characterization of toxins isolated from Pfiesteria piscicida. Environ. Health Perspect. 109, 739–743 (2001)

    CAS  PubMed  PubMed Central  Google Scholar 

  9. Glasgow, H. B., Burkholder, J. M., Mallin, M. A., Deamer-Melia, N. J. & Reed, R. E. Field ecology of toxic Pfiesteria complex species and a conservative analysis of their role in estuarine fish kills. Environ. Health Perspect. 109, 715–730 (2001)

    CAS  PubMed  PubMed Central  Google Scholar 

  10. Noga, E. J., Levine, J. F., Dykstra, M. J. & Hawkins, J. H. Pathology of ulcerative mycosis in Atlantic menhaden. Dis. Aquat. Org. 4, 189–197 (1988)

    Article  Google Scholar 

  11. Dykstra, M. J. et al. Ulcerative mycosis: a serious menhaden disease of the southeastern coastal fisheries of the United States. J. Fish Dis. 12, 175–178 (1989)

    Article  Google Scholar 

  12. Callinan, R. B. in Proc. ODA Regional Sem. Epizootic Ulcerative Syndrome (eds Roberts, R. J., Campbell, B. & MacRae, I. H.) 248–252 (The Aquatic Animal Health Research Institute, Bangkok, 1994)

    Google Scholar 

  13. Blazer, V. S. et al. Aphanomyces as a cause of ulcerative skin lesions of menhaden from Chesapeake Bay tributaries. J. Aquat. Anim. Health 11, 340–349 (1999)

    Article  Google Scholar 

  14. Blazer, V. S. et al. Aphanomyces invadans in Atlantic menhaden along the East Coast of the United States. J. Aquat. Anim. Health 14, 1–10 (2002)

    Article  Google Scholar 

  15. Kiryu, Y., Shields, J. D., Vogelbein, W. K., Zwerner, D. E. & Kator, H. Induction of skin ulcers in Atlantic menhaden by injection and water-borne exposure to the zoospores of Aphanomyces invadans. J. Aquat. Anim. Health 14, 11–24 (2002)

    Article  Google Scholar 

  16. Vogelbein, W. K., Shields, J. D., Haas, L. W., Reece, K. S. & Zwerner, D. E. Skin ulcers in estuarine fishes: A comparative pathological evaluation of wild and laboratory-exposed fish. Environ. Health Perspect. 109, 687–693 (2001)

    CAS  PubMed  PubMed Central  Google Scholar 

  17. Schnepf, E. & Deichgräber, G. “Myzocytosis”, a kind of endocytosis with implications on compartmentation in endosymbiosis. Observations in Paulsenella (Dinophyta). Naturwissenschaften 71, 218–219 (1983)

    Article  ADS  Google Scholar 

  18. Glasgow, H. B., Burkholder, J. M., Morton, S. L. & Springer, J. A second species of ichthyotoxic Pfiesteria (Dinamoebales, Dinophyceae). Phycologia 40, 234–245 (2001)

    Article  Google Scholar 

  19. Burkholder, J. M., Marshall, H. G., Glasgow, H. B., Seaborn, D. W. & Deamer-Melia, J. The standardized fish bioassay procedure for detecting and culturing actively toxic Pfiesteria, used by two reference laboratories for Atlantic and Gulf Coast states. Environ. Health Perspect. 109, 745–756 (2001)

    CAS  PubMed  PubMed Central  Google Scholar 

  20. Spero, H. J. & Moree, M. D. Phagotrophic feeding and its importance to the life cycle of the holozoic dinoflagellate, Gymnodinium fungiforme. J. Phycol. 17, 43–51 (1981)

    Article  Google Scholar 

  21. Schnepf, E. & Elbrächter, M. Nutritional strategies in dinoflagellates—a review with emphasis on cell biological aspects. Eur. J. Protistol. 28, 3–24 (1992)

    Article  CAS  Google Scholar 

  22. Vogelbein, W. K. et al. in Agenda: Symp. Harmful Marine Algae in the U.S. 81 (The Marine Biological Laboratory, Woods Hole, Massachusetts, 2000).

    Google Scholar 

  23. Shumway, S., Springer, J., Burkholder, J. M., Glasgow, H. B. in Agenda: Symp. Harmful Marine Algae in the U.S. 64 (The Marine Biological Laboratory, Woods Hole, Massachusetts, 2000).

    Google Scholar 

  24. Melo, A. C., Moeller, P. R., Glasgow, H. B., Burkholder, J. M. & Ramsdell, J. S. Microfluorimetric analysis of a purinergic receptor (P2X7) in GH4C1 rat pituitary cells: Effects of a bioactive substance produced by Pfiesteria piscicida. Environ. Health Perspect. 109, 731–737 (2001)

    CAS  PubMed  PubMed Central  Google Scholar 

  25. El-Nabawi, A. et al. The N-methyl-d-aspartate neurotransmitter receptor is a mammalian brain target for the dinoflagellate Pfiesteria piscicida toxin. Toxicol. Appl. Pharmacol. 169, 84–93 (2000)

    Article  CAS  Google Scholar 

  26. Marshall, H. M. et al. Comparative culture and toxicity studies between the toxic dinoflagellate, Pfiesteria piscicida, and a morphologically similar cryptoperidiniopsoid dinoflagellate. J. Exp. Mar. Biol. Ecol. 255, 65–74 (2000)

    Article  Google Scholar 

  27. Burkholder, J. M. & Glasgow, H. B. Pfiesteria piscicida and other toxic Pfiesteria-like dinoflagellates: behaviour, impacts and environmental controls. Limnol. Oceanogr. 42, 1052–1075 (1997)

    Article  ADS  Google Scholar 

  28. Litaker, R. W., Vandersea, M. W., Kibler, S. R., Madden, V. J., Noga, E. J. & Tester, P. A. Life cycle of the heterotrophic dinoflagellate Pfiesteria piscicida (Dinophyceae). J. Phycol. 38, 442–463 (2002)

    Article  Google Scholar 

  29. Berry, J. P. et al. Are Pfiesteria species toxicogenic? Evidence against production of ichthyotoxins by Pfiesteria shumwayae. Proc. Natl Acad. Sci. USA (in the press)

  30. Steidinger, K. A. et al. Pfiesteria piscicida gen. et. sp. nov. (Pfiesteriaceae fam. nov.), a new toxic dinoflagellate with a complex life cycle and behaviour. J. Phycol. 32, 157–164 (1996)

    Article  Google Scholar 

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C. Squyars, A. Miller, P. Blake, D. Zwerner, E. Westcott, V. Foster, L. Ott, E. Walker, J. Watts, W. Ribeiro and K. Hudson contributed significantly to this investigation. E. M. Burreson provided support and critical review. This work was funded in part by ECOHAB (Ecology and Oceanography of Harmful Algal Blooms) grants from the EPA, the EPA with the National Oceanic and Atmospheric Administration (NOAA), and from the NOAA; the Commonwealth of Virginia's Pfiesteria Initiative; and the Centers for Disease Control and Prevention. We thank T. Shedd and the US Army Center for Environmental Health Research for the lease of the BSL3 laboratory.

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Correspondence to Wolfgang K. Vogelbein.

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Vogelbein, W., Lovko, V., Shields, J. et al. Pfiesteria shumwayae kills fish by micropredation not exotoxin secretion. Nature 418, 967–970 (2002).

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