Effects of a red-tide toxin on fish hearing

Z. Lu, S. M. Tomchik

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


Red tides are formed from blooms of marine algae. Among them, the dinoflagellate (Karenia brevis) that is responsible for Florida red tides can release many types of natural toxins, which cause massive kills of marine animals, including endangered species, and threaten human health. This study was to investigate whether or not a neurotoxin, brevetoxin-3, purified from Florida red tides affects hearing sensitivity of a teleost fish, the goldfish (Carassius auratus). LD50 of the goldfish that were intraperitoneally injected with brevetoxin-3 was 0.068 μg g-1. Evoked auditory brainstem responses were recorded, and hearing threshold was determined using a correlation method. By comparing thresholds of fish before and after a sublethal-dose injection (0.064 μg g-1) of the toxin, we found that brevetoxin-3 significantly reduces auditory sensitivity up to 9 dB at low frequencies (100 Hz and 500 Hz), but not at a high frequency (2,000 Hz). Reduction of hearing sensitivity was recovered within 24 h. To our knowledge, this is the first study showing a natural red-tide toxin causes minor hearing loss in vertebrates. Results of the study indicate that brevetoxin-3 could affect hearing capabilities of marine animals that survived exposure to red tides. Mechanisms of the toxin-induced reduction of hearing sensitivity are discussed.

Original languageEnglish (US)
Pages (from-to)807-813
Number of pages7
JournalJournal of Comparative Physiology A: Neuroethology, Sensory, Neural, and Behavioral Physiology
Issue number10
StatePublished - Nov 1 2002


  • Audiogram
  • Auditory brainstem response
  • Brevetoxin
  • Goldfish
  • Neurotoxin

ASJC Scopus subject areas

  • Animal Science and Zoology
  • Physiology
  • Physiology (medical)
  • Behavioral Neuroscience
  • Neuroscience(all)


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