[MARMAM] New Publication: Exposure to domoic acid is an ecological driver of cardiac disease in southern sea otters (Megan Moriarty)

Megan Moriarty memoriarty at ucdavis.edu
Sun Jan 17 13:44:12 PST 2021

Dear colleagues,

My collaborators and I are excited to announce the publication of our new paper
"Exposure to domoic acid is an ecological driver of cardiac disease in
southern sea otters" in *Harmful Algae*. The abstract is below and the full
article is available open-access here
Please feel free to reach out to me with any questions.

Happy New Year!
Megan Moriarty

Harmful algal blooms produce toxins that bioaccumulate in the food web and
adversely affect humans, animals, and entire marine ecosystems. Blooms of
the diatom Pseudo-nitzschia can produce domoic acid (DA), a toxin that most
commonly causes neurological disease in endothermic animals, with
cardiovascular effects that were first recognized in southern sea otters.
Over the last 20 years, DA toxicosis has caused significant morbidity and
mortality in marine mammals and seabirds along the west coast of the USA.
Identifying DA exposure has been limited to toxin detection in biological
fluids using biochemical assays, yet measurement of systemic toxin levels
is an unreliable indicator of exposure dose or timing. Furthermore, there
is little information regarding repeated DA exposure in marine wildlife.
Here, the association between long-term environmental DA exposure and fatal
cardiac disease was investigated in a longitudinal study of 186
free-ranging sea otters in California from 2001 – 2017, highlighting the
chronic health effects of a marine toxin. A novel Bayesian spatiotemporal
approach was used to characterize environmental DA exposure by combining
several DA surveillance datasets and integrating this with life history
data from radio-tagged otters in a time-dependent survival model. In this
study, a sea otter with high DA exposure had a 1.7-fold increased hazard of
fatal cardiomyopathy compared to an otter with low exposure. Otters that
consumed a high proportion of crab and clam had a 2.5- and 1.2-times
greater hazard of death due to cardiomyopathy than otters that consumed low
proportions. Increasing age is a well-established predictor of cardiac
disease, but this study is the first to identify that DA exposure affects
the risk of cardiomyopathy more substantially in prime-age adults than aged
adults. A 4-year-old otter with high DA exposure had 2.3 times greater risk
of fatal cardiomyopathy than an otter with low exposure, while a 10-year
old otter with high DA exposure had just 1.2 times greater risk. High
Toxoplasma gondii titers also increased the hazard of death due to heart
disease 2.4-fold. Domoic acid exposure was most detrimental for prime-age
adults, whose survival and reproduction are vital for population growth,
suggesting that persistent DA exposure will likely impact longterm
viability of this threatened species. These results offer insight into the
pervasiveness of DA in the food web and raise awareness of under-recognized
chronic health effects of DA for wildlife at a time when toxic blooms are
on the rise.

Megan Moriarty, DVM, MPVM, PhD
Free-ranging Wildlife Health Resident Veterinarian
California Department of Fish and Wildlife
Karen C. Drayer Wildlife Health Center | One Health Institute
University of California Davis
memoriarty at ucdavis.edu
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