Oceans and human health: from harmful algae to holiday dinners

A guest blog by Emma Hiolski

I never expected that my research on the neurological effects of the seafood toxin domoic acid would be connected to holiday traditions in Northern California. The delayed start of the Dungeness crab season this year, caused by a massive bloom of toxic algae in the Pacific Ocean, means that seafood consumers in Northern California may not get to enjoy their traditional crab dinners this holiday season. I was aware that harmful algal blooms can contribute to closure of recreational and commercial fisheries, but didn’t fully appreciate the potential negative impacts on fishermen, consumers, and local communities until now. As I anticipate returning home to the Midwest for my own holiday celebrations, I am conscious of the need to continue improving our understanding of the connections between oceans and human health.

  The start of the Dungeness crab season was delayed due to the presence of domoic acid in seafood along the coast of California, Oregon, and Washington (image from California Department of Fish and Wildlife News)

 

The start of the Dungeness crab season was delayed due to the presence of domoic acid in seafood along the coast of California, Oregon, and Washington (image from California Department of Fish and Wildlife News)

Domoic acid was measured across an unusually wide geographic range in a number of marine wildlife species during the summer of 2015 (figure courtesy of NOAA Fisheries, Seattle, WA).

Domoic acid was measured across an unusually wide geographic range in a number of marine wildlife species during the summer of 2015 (figure courtesy of NOAA Fisheries, Seattle, WA).

Domoic acid is produced by algae in the ocean, and moves up the marine food web to poison marine wildlife – and occasionally humans – through contaminated baitfish and shellfish. At high-enough levels, domoic acid can cause seizures and brain damage, and has been responsible for numerous sea lion and sea bird deaths and stranding events along the west coast of North America. Although seafood monitoring programs and regulations protect humans from exposure to high levels of domoic acid, like the California Department of Public Health and Fish & Wildlife monitoring the Dungeness crab fishery, consuming shellfish can still result in exposure to levels of domoic acid below the regulatory limit. My research specifically targets the fact that we do not know how the brain responds to frequent low-level exposure. This knowledge gap is especially relevant to seafood consumers and commercial and recreational fishermen that regularly consume shellfish multiple times a week. 

To address this knowledge gap, I use a wide variety of methods to uncover small-scale changes in the brain caused by repeated low-level domoic acid exposure. Using genomic tools – measuring whether genes are turned on or off – I’ve discovered that genes involved in brain development are reactivated, which could indicate that the brain is either trying to repair damage, or that domoic acid inappropriately stimulates developmental pathways. We have yet to determine whether those changes could noticeably impede brain function or behavior in exposed wildlife or humans. To learn more on that front, I have been collaborating with a physics group at UCSC (the Santa Cruz Institute for Particle Physics) to record the electrical activity of hundreds of neurons to measure their response to prolonged low-level exposure to domoic acid. Learning about the way low-level domoic acid changes the electrical activity and interconnectedness of neurons in the brain can help us understand whether normal brain processes, like learning and memory, could be disrupted. 

Top photo: Recreational clam harvesting on the coast of Washington State must be highly regulated to protect humans from exposure to high levels of environmental toxins, including domoic acid (image courtesy of WA Dept of Fish & Wildlife).  Bottom photo: Emma Hiolski (the author) measuring small-scale changes in the brain caused by prolonged low-level exposure to domoic acid using a confocal microscope at UC Santa Cruz.  

Top photo: Recreational clam harvesting on the coast of Washington State must be highly regulated to protect humans from exposure to high levels of environmental toxins, including domoic acid (image courtesy of WA Dept of Fish & Wildlife). 

Bottom photo: Emma Hiolski (the author) measuring small-scale changes in the brain caused by prolonged low-level exposure to domoic acid using a confocal microscope at UC Santa Cruz.

 

I am also collaborating with scientists at the University of Washington and the NOAA Fisheries center in Seattle, WA, to determine whether prolonged low-level exposure to domoic acid disrupts learning and memory. My specific goal is to measure the microscopic changes in the brain that accompany any domoic acid-induced deficits, and to examine whether any changes might be reversible. Ultimately, these projects aim to further our understanding of whether domoic acid poses unknown health risks to humans, an especially relevant question given the recent record-setting toxic algae bloom and unprecedented fisheries closures. And as ocean temperatures continue to increase, we are likely to see increases in the occurrence of these warm-water-loving blooms and accompanying increases in the prevalence of domoic acid. A better understanding of the links between our oceans and human health can help balance the need to protect livelihoods and cultural traditions along our coasts with the need to protect people from potential health risks.

Emma Hiolski is a PhD student in the Microbial and Environmental Toxicology (METX) Department at UCSC