Deep Reef Diving with Sarah Heidmann

Rebreathers, scientific diving, and mesophotic reefs, Sarah is the master of them all….


Hey Sarah, thanks for joining us, tell us a bit about yourself.

I grew up in northern California, completed my undergraduate degree at Oregon State, and earlier this year I finished my master’s degree in marine and environmental sciences at the University of the Virgin Islands. I now work as a full-time research technician at UVI, based on the island of St. Thomas in the US Virgin Islands (USVI). A formative experience early on in my marine biology career was being trained in scientific diving during an undergraduate study abroad program in Bonaire. After I returned to Oregon, I knew I had to keep diving even in the cold water. I’ve been going strong underwater ever since!

How did you become so involved with the ocean? What drew you to it in the beginning?

My parents took me to the Monterey Bay Aquarium a lot growing up. It’s an amazing place, both educational and visually stunning. I always insisted on showing up early to get a front row seat for the dive presentations, seeing a diver give an educational talk from inside the exhibit enthralled me every time, and I knew I wanted to be on the other side of the glass. In 2014, I fulfilled this lifelong dream by becoming an interpretive diver for the Oregon Coast Aquarium. Everyone wants to be a marine biologist as a kid, I just never lost that vision or my passion for it.

How did you get to where you are now?

Although I loved working at an aquarium after I finished my undergraduate degree, I knew I wanted to pursue more educational opportunities. UVI, although not widely known, offered me a chance to complete my degree with incredibly easy access to the marine environment and permanent warm weather, although it required me to step out of my comfort zone to move so far from home. Living on an island has its challenges, but it has made me a more resourceful person and I’m so glad I decided to move here. I worked hard throughout my studies, learning everything someone would teach me. After graduation I was hired as a research technician, and here I am!   

What does a day in your life look like?

I love my job because I get paid to spend so much time underwater! Last year, even taking three months off due to the aftermath from hurricanes Irma and Maria, I did about 200 dives. There are many different tasks for various research projects that need to be completed on SCUBA, including coral surveys, fish surveys, algae collection, equipment maintenance, photography, and much more. When I’m not diving, I’m entering or analysing the data we collected, or writing it up for a manuscript to be published.


You have some experience with re-breathers, tell us about what this is like compared to normal diving, and some of the benefits it has to your work.

Although it feels weird at first, after some practice, diving a rebreather feels much less invasive to the reef and its inhabitants than open-circuit diving. Using a rebreather can provide extended bottom times, shorter decompression, and a more natural-feeling underwater experience. Normally fish are afraid of the bubbles that open-circuit divers produce, but on a rebreather there are none to scare them away! To them, you just look like another very large, awkward fish, and they often come close to investigate. I’ve seen many more juvenile fish while diving closed-circuit, and have more frequently observed interesting behaviors such as cleaning and aggression. In terms of the benefits for the data we collect, we’re able to get a more accurate picture of what fish are living on the reef when they’re not hiding under coral heads. Additionally, we can spend more time collecting data on deeper reefs.

Tell us about some of your current research projects

UVI is an emerging force in the study of mesophotic reefs - those just deeper than recreational SCUBA depths and thus difficult to access and poorly understood. Rebreathers increase our capacity to collect data on the fish and coral communities, which are frequently quite different from those on shallower reefs.

For my master’s thesis, I used passive acoustic telemetry to track the movements of mutton snapper, both at a home range area and at a spawning aggregation. I am currently writing the manuscript for publication, and continue to analyze data on the movements of many other species of fish around the USVI.

I also manage the field collection of data for monitoring of ciguatera fish poisoning in the USVI. St. Thomas in particular is a hotspot for the illness, so we sample several reefs for biological and environmental variables that might help us better understand what causes it to flourish.


How do you hope your voice and work will influence others?

A lot of people are scared of the ocean and don’t know very much about it. I’d like to contribute to changing the general public’s perspective to understand that it’s an amazing place- not something to be scared of, but rather to respect and protect. So far, I have just used my Instagram feed to showcase some of the cool work I’ve been doing and the animals I’ve seen. I’d like to expand my efforts but am not certain yet how I want to approach it.

Which ocean species is on your bucket list to see?

I’ve already crossed off many animals that were on my bucket list, such as sailfish, groupers, ocean sunfish, whales, seals and sea lions, manta rays, and sharks. I’m always excited to see new species, no matter how small. I would really like to see a whale shark, they have been seen in St. Thomas before, so I’m keeping my fingers crossed!

What is one thing you wish someone had told you/taught you a long time ago?

There are many things I wish someone had told me a long time ago, but they all mostly boil down to this: don’t be scared, just do what you love. Once you find your passion, stick to it, and talk to people about it, and further opportunities will present themselves. Marine biology is a small world and connections can get you places! Also, your focus and interests may change over time, and that’s okay. Stepping out of your comfort zone is the best way to get involved and make a difference, and become a better person along the way.


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