As Upwell’s wildlife veterinarian, Dr. Heather Harris’ work is part of Upwell's new ecosystem health program. The aim of this program is to better understand specific environmental threats that present health risks to sea turtles and to demonstrate to the wider public how sea turtles act as sentinels for the health of our oceans. Dr. Harris has a DVM in Veterinary Medicine and MPVM in Wildlife Disease Ecology from the University of California, Davis. She is a diplomate of the American College of Veterinary Preventive Medicine.
Photo: Dr. Heather Harris and Dr. George Shillinger of Upwell, National Oceanic and Atmospheric Administration (permit 21111)
The sky is clearing as the Sheila B pulls out of Pillar Point Harbor, leaving Half Moon Bay behind us as we move offshore. Standing on the bow bridge, salt spray in our faces, we pass over areas thick with jellies just below the surface. We see high densities of brown sea nettles (Chrysaora fuscescens) with long undulating oral arms trailing below, and less frequently clear round moon jellies (Aurelia spp.). Occasionally we pass remnant fragments of jellies and overturned bells, evidence of a recent foraging bout. It could be one of the elusive leatherback turtles we are searching for, or another creature who shares the same taste preference for jellies in these local waters, the ocean sunfish (Mola mola). When the molas are abundant and lounging lazily at the surface, we can see their light mottled shape beneath the water as we approach, and we call out a warning to the captain to steer the boat away from these curious gentle giants. As the aerial team follows their survey lines above, the boat crew continuously scans the water for a flash of the telltale shiny bulbous head and smooth dark linear ridges barely breaking the surface. In calm flat ocean, their dark silhouettes pop out from the smooth background. But in rough conditions they can virtually disappear into the glare and whitewash. On days without aerial support, this search image is all we have to go on.
Photo: Dr. Heather Harris with Chrysaora jellyfish, National Oceanic and Atmospheric Administration (permit 21111)
I joined the team as lead veterinarian for the leatherback project nearly fifteen years ago, when I was a graduate student at UC Davis conducting a health assessment of the foraging population in central California. Since that time, my role has been to provide veterinary support for all aspects of the project. As a wildlife veterinarian and specialist in preventive medicine, I work not only hands-on with turtles in the field but also on some of the less sexy but equally important components of conducting necropsies (animal autopsies) on stranded turtles, permit review, research protocol development, grant writing, data analysis, and publication. During our leatherback capture operations, my primary job is to monitor turtles on the boat to reduce stress and ensure they remain stable and healthy throughout the process of tagging and sampling. I conduct physical exams, evaluate body condition, and collect biological samples to investigate their health. For example, if a turtle opportunistically poops on the boat deck, I immediately grab a large syringe to collect the watery material to test for exposure to marine biotoxins from harmful algal blooms.
Photo: Leatherback sea turtle with satellite tracker, National Oceanic and Atmospheric Administration (permit 21111)
I have found fairly high levels of the biotoxin domoic acid in leatherbacks and four species of jellies in central California. This is the same toxin frequently in the news that causes mass strandings of sick marine mammals and large-scale fisheries closures to prevent amnesic shellfish poisoning in humans. Although serious health effects from this toxin are well described in humans and marine mammals, the impacts to sea turtles are not well understood. As harmful algal blooms continue to increase along the west coast as a result of ocean warming and nutrient input, it is critical to learn more about the effects on critically endangered and declining leatherbacks on critical foraging grounds. By taking this “One Health” approach, we recognize the interconnection between the health of humans, animals, and our shared environment.