Trophic transfer of the marine algal biotoxin domoic acid to the North Atlantic right whale, Eubalaena glacialis
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Date
2014-08-18
Authors
Leandro, Luis Frazao da Silva
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Abstract
Population recovery of the highly endangered North Atlantic right whale Eubalaena glacialis has been challenged severely by reproductive abnormalities and compromised health. Of the several factors hypothesized as contributing to the observed reproductive dysfunction in right whales, exposure to marine biotoxins such as domoic acid (DA) has received comparatively little consideration. The present study assessed the occurrence of DA in right whale feces, copepods and krill, and phytoplankton collected from April - September of 2005 and 2006 on the whales’ spring and summer feeding grounds in the western N. Atlantic. The presence of DA was detected by a surface plasmon resonance (SPR) optical immunosensor (with selected confirmation by mass spectrometry) in 69 right whale fecal samples, 6 krill samples and 32 copepod samples, many of which were largely dominated by stage V Calanus finmarchicus copepodites (n=9). Frustules of several potential DA-producing diatoms of the genus Pseudo-nitzschia were identified in right whale feces and phytoplankton by electron microscopy (EM). EM also revealed an abundance of C. finmarchicus mandibles in E. glacialis feces. Grazing and toxin accumulation/depuration experiments performed under controlled laboratory conditions demonstrated the ability of C. finmarchicus to consume DA-producing algae and retain toxin in its tissues after removal of the DA source. These findings establish the potential of C. finmarchicus to facilitate DA trophic transfer in marine food webs and further confirm that E. glacialis is exposed to this toxin through ingestion of DA-contaminated copepods while feeding.
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Keywords
Right whales; Domoic acid -- Toxicology; Algal blooms