Domoic acid in milk of free living California marine mammals
indicates lactational exposure occurs.
California sea lions (Zalophus
californianus) have stranded along the California coastline over the last
15 years due to domoic acid (DA) toxicosis (Scholin et al., 2000; Gulland et al.,
2002). Domoic acid exposure also causes reproductive failure in California sea
lions (Brodie et al., 2006; Goldstein
et al.,2009) and controlled studies
have demonstrated that DA can cross the placenta and be detected in milk
causing developmental effects in young rodents (Maucher and Ramsdell, 2005;
2007). To determine the distribution of DA in naturally exposed marine mammals
and the potential for lactational transfer, a range of samples were collected
opportunistically from 54 stranded marine mammals in California. Between 2005
and 2013, samples of milk, urine, feces, bile, stomach contents, serum, aqueous
humor, amniotic fluid, and pericardium fluid were collected at necropsy and
stored at -80 C until processing from California sea lions (n=43), harbor seals
(Phoca vitulina) (n=1), northern fur
seals (Callorhinus ursinus) (n=2),
and harbor porpoises (Phocoena phocoena)
(n= 9). The majority of samples were collected within one week of stranding,
but some as late as 52 days after live stranding and rehabilitation. Samples
were tested for domoic acid using an enzyme-linked immunosorbent assay (ELISA)
at the NOAA NMFS Northwest Fisheries Science Center in Seattle, WA, USA.
Domoic acid was detected in milk samples (n = 55) at levels ranging from 1.1
ng/ml to 142.6 ng/ml, and in 75% of these animals DA was also detected in other
bodily fluids. These marine mammals nurse their young for 6 months to 2 years,
potentially exposing them to DA which could cause abnormal development or
neurological effects as seen in rats (Xi et
al., 1997). Understanding the extent of transfer of DA to developing young
will help further our understanding of the long term effects of DA on
development.
Thank you,
Lauren Rust