Movement, dive behavior, and survival of California sea lions (Zalophus californianus) posttreatment for domoic acid toxicosis

Kate Thomas, James T. Harvey, Tracey Goldstein, Jerome Barakos, Frances Gulland

Research output: Contribution to journalArticle

23 Scopus citations

Abstract

Domoic acid (DA) is a neuroexcitatory toxin increasingly causing strandings and mortality of marine mammals. The hippocampus of mammalian brains, associated with learning, memory, and spatial navigation, is one of the predominant regions affected by DA exposure. California sea lions stranding from 2003 to 2006 as a result of DA toxicosis were classified as having acute (n = 12) or chronic neurologic (n = 22) clinical signs. Chronic neurologic cases were examined by magnetic resonance imaging to determine the extent of brain damage related to DA exposure. Brain damage included hippocampal and parahippocampal atrophy, temporal horn enlargement, and pathological T2 hyperintensity. Posttreatment, animals were fitted with satellite transmitters and their movement and dive behaviors compared with those of a control group. The only significant difference between acute and chronic animals was distance traveled per day. There were, however, significant differences between chronic neurologic cases and controls: chronic neurologic cases dove shallower for shorter durations, traveled further from shore, and spent less time hauled out and more time surface swimming than control animals. There was no relationship between severity of brain damage and behavioral patterns for chronic neurologic cases. Sea lions with chronic neurologic changes had a poor prognosis for survival following release.

Original languageEnglish (US)
Pages (from-to)36-52
Number of pages17
JournalMarine Mammal Science
Volume26
Issue number1
DOIs
StatePublished - Jan 2010
Externally publishedYes

Keywords

  • California sea lions
  • Domoic acid
  • Harmful algal blooms
  • Hippocampal atrophy
  • Magnetic resonance imaging (MRI)
  • Pseudo-nitzschia
  • Zalophus californianus

ASJC Scopus subject areas

  • Aquatic Science
  • Ecology, Evolution, Behavior and Systematics

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