Exposure of the North Atlantic right whale Eubalaena glacialis to the marine algal biotoxin, domoic acid

摘要

In addition to ship collisions and fishing gear entanglements, recovery of the highly endangered North Atlantic right whale Eubalaena glacialis has been challenged by reproductive abnormalities and compromised health. Of the 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 collected from April through September of 2005 and 2006 on the whales' feeding grounds along the northeastern USA and eastern Canada. DA was detected by surface plasmon resonance (SPR) in 69 right whale fecal samples, 6 krill samples, and 32 copepod samples. Many of the latter were dominated largely by Stage V Calanus finmarchicus copepodites. DA detection by SPR in fecal and zooplankton collections was verified by receptor binding assay and confirmed using liquid chromatography - tandem mass spectrometry (LC-MS/MS). Moreover, LC-MS/MS determined the presence of a putative methylated DA metabolite in all fecal and zooplankton samples analyzed. Frustules of several potentially toxic Pseudo-nitzschia spp. were identified in whale feces and phytoplankton samples by light and electron microscopy. Electron microscopy also revealed an abundance of C. finmarchicus mandibles in right whale feces. These findings confirm that E. glacialis was exposed to DA for several months, likely through ingestion of a DA-contaminated copepod vector. The extent to which this algal biotoxin may contribute to the failed recovery of the E. glacialis population warrants further investigation.