Sea Cucumber Scientist: Leah Dann

By Haley Vogel

This week we interviewed the lovely Leah Dann about her experience as a Marine Biologist and her research on Sea Cucumbers in the Phillipines, here’s what she had to say.

Hey LEAh! Want to tell our readers a little about you?

My name is Leah Dann, I’m a PhD student at the University of Queensland School of Biological Sciences. I’m a dual Australian-American citizen and have conducted research in both countries as well as in other locations. I enjoy curling up with a cup of tea and a good book or TV show, rock climbing, and scuba diving.

What initially drew you towards a the ocean and how did you get to where you are now?

I’ve loved the ocean since I was really young, it’s something I’ve always been drawn to. Being in the ocean feels like an adventure, there’s always something new and exciting to see and experience. I graduated high school with no idea of what to do with my life, so I went to uni and took some general studies courses. I had a biology class my first term and became interested in the research that the professor was conducting, so I asked him about a career in marine biology. He invited me on a marine research trip, and from that point forward I knew I wanted to be a scientist. I participated in as many research projects as I could during the course of my Bachelors and Masters degrees, and started my PhD this year.

Leah conducting research on Sea Cucumbers in the Phillipines

Leah conducting research on Sea Cucumbers in the Phillipines

Tell us about some of your research as a marine biologist?

The first project that I considered “mine” was some work I did with a professor and another student studying the impacts of sea cucumbers on coral reef health in the Philippines, it was a really fun experience. I was scuba diving or driving a boat pretty much every day to collect data and then sitting in coffee shops while analysing data and writing up reports. We found that sea cucumbers not only remove harmful sediment from corals, but that they are also associated with lower instances of coral disease! I ultimately presented this research at a conference, which was a rewarding experience. For my Masters project I studied seagrass beds and some marine isopods that inhabit them, which was also a fun project that involved working both in the field and in the lab!

Your research on the sea Cucumbers found out some pretty amazing results in regards to the health of coral reefs, can you tell us some more about this?

Coral reef ecosystems are incredibly important, as they contain high biodiversity and provide invaluable ecosystem goods and services. Unfortunately, reefs are in decline and are incredibly sensitive to reduced water quality caused by temperature changes, pollution, and sedimentation from dredging and terrestrial runoff. Increased sedimentation has been linked to an increase in coral disease and mortality. Grazing sea cucumbers such as P. graeffei pick up sediment and algae from coral reefs with their feeding tentacles, so we wanted to see if they are associated with improved coral health. We dove along a coral reef, surveying random quadrats to determine substrate composition of the reef and to examine substrate preference of the sea cucumbers.

We used syringes to collect sediments from an area adjacent to the cucumber and from the area where the cucumber had just fed to determine percent sediment removal. We also examined substrate under the cuke poop to determine whether redeposition of the sediment onto the reef was occurring. Using statistical analyses, we found that sea cucumbers prefer to feed on coral rather than sand, and that they reduce the sediment mass on corals by over 60% as they move along the reef. However, they tend to not defecate on live coral and therefore do not redeposit much sediments onto the reef. Studies have shown that this level of sediment removal from corals tends to increase coral survival and decrease the prevalence of coral diseases.

Through underwater surveys of coral communities with and without sea cucumbers, we showed that coral colonies with sea cucumbers present were significantly less likely to be diseased than those without, indicating an association between cucumber presence and healthier reefs. This study shows the importance of sea cucumbers to coral reef health. I think that people tend to forget about the less charismatic animals such as the sea cucumbers, and as a result these animals often receive inadequate protection. Bringing attention to the vital roles of these creatures will hopefully lead to an increase in conservation.

You’ve just started your PhD, tell us about what a day in your life looks like currently.

Each day is different, but reading and writing are pretty much a daily activity. My favourite days are when I go into the lab or field. I love doing fieldwork outside, it’s really what drew me to research in the first place. Writing research proposals, grants, permits, journal articles, etc. is a huge part of being able to do that field and lab work, and it is really fun to analyse data and then present solid research findings to other scientists and to the general public.

Sea Cucumbers like this one can help corals stay healthy

Sea Cucumbers like this one can help corals stay healthy

How do you hope that your work will influence others?

Nature is an amazing thing to experience and it provides us with many important goods and services; I want to protect natural environments both on land and in the sea for future generations to enjoy and use. Without intervention and change, many species will soon go extinct, never to be seen again. I hope that my work can provide direction as to the work and policies needed to prevent extinctions and that my voice inspires others to do their part to preserve nature.

You mentioned Fieldwork being one of your favourite parts of the job, tell us about some interesting experiences you have had in the field.

Fieldwork is always an adventure. I once tied up a boat improperly and had to swim out in 8-degree water with no wetsuit to retrieve it. I’ve been entangled in kelp in an area with low visibility and strong currents, completely reliant on my dive buddy to extricate me. I’ve had boat motors die multiple times, forcing me and a buddy to row impressive distances to reach a dock. Patching up boats was a regular part of my fieldwork experiences. I got lost (or lost my dive sites) constantly. Luckily, I’ve never experienced any serious injuries, so most of my mishaps ended up being fun memories to look back on. Things don’t always go smoothly, but if you’re prepared for anything and work hard, it’s amazing what you can accomplish and how much fun you can have doing research!

Who have been some of your biggest inspirations in getting to where you are now?

Some more famous people include the likes of Jean-Michel Cousteau and Steve Irwin. My most directly influential mentors have been Dr. Jim Nestler - the professor who got me interested in research in the first place, Dr. Dave Cowles - my Masters supervisor who has an encyclopedic knowledge of marine invertebrates, and Dr. John Dwyer - my current advisor.

It’s not the end of the world if you fail… Learn, Move on and Work hard.

Leah Dann

Do you have an ocean species on your bucket list to see?

Ruby Seadragon (Phyllopteryx dewysea)!!!


I've had an amazing experience as a woman in a scientific field, largely because the supportive nature of the universities/organizations I have been affiliated with. I know that female scientists in developing nations and even in first world countries often face many obstacles, and I feel very fortunate that the people surrounding me in my career did not have prejudicial attitudes. Women are becoming more and more involved in marine science and making remarkable contributions to the field, which I believe is a great thing! I think that with the support of the scientific community, women will have an increasing role in scientific research and will hopefully face fewer obstacles as time goes on.

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

It’s not the end of the world if you fail or if things don’t go the way you want. Learn, move on, work hard, and eventually you’ll probably be thankful for those perceived failures because without them you wouldn’t be where you are now.

and Last but not least, if there was one message you could get across to the general public, what would it be?

To use the ocean and its resources responsibly and sustainably, to protect it through environmentally-friendly practices and support of policies that will reduce pollution and emissions, and to enjoy the ocean and all the beautiful things it has to offer!