Diving Deeper with Dr. Jodie Rummer

Briefly can you describe the focus of your research and the species you work on?

My research examines the effects of future climate change scenarios (i.e., elevated temperatures, elevated CO2, low oxygen, increased turbidity) on physiological performance and movement of reef/tropical sharks and fish. I choose species according to the environmental conditions they are already experiencing. For example, the epaulette shark makes a great model for a species that would presumably be quite tolerant to dramatically fluctuating environmental conditions because of the habitat it occupies. Epaulette sharks bury themselves in the coral reefs and shelter in small caves and crevices. They are active at night when low tides and respiring coral can cause oxygen levels in the shallow pools to decrease and CO2 levels to increase greatly. Also, given they are found in shallow coral reef flats, they also experience dramatic temperature changes. Most of my work thus far has been on adults, but my group is also currently looking at early stages of development. This poses particularly interesting questions because usually animals can move if conditions are unfavourable. Epaulette sharks develop in egg cases that are laid on the reef, sometimes tucked deep in the reef matrix. Therefore, the egg and developing embryo inside will experience all of the fluctuations in water quality that occur, as the embryo cannot move until the egg hatches, which sometimes takes several months. The hatched neonate also poses an interesting model, as they are small and don’t yet swim to move around but rather “walk” using their paired fins. Being so small, they also use the cracks and crevices of the reef as shelter and protection from predation and therefore would also need to be quite tolerant of fluctuating water quality. On the other end of the spectrum, the faster, more active, and more “shark-like” species may not have as well developed tolerance to changes in water quality, as they do not see those conditions as often. I am looking at blacktip reef and sickle fin lemon sharks to examine this. But an interesting caveat here is that the mothers pup the babies (sometimes 10-12 at a time) in very shallow lagoons and mangroves that would also experience dramatic fluctuations in water quality. The question is then, do the babies have to make physiological tradeoffs to live in challenging lagoons in order to avoid predation and exploit food sources? So, there may be a developmental component where babies can acclimate to changes in temperature, oxygen, CO2, etc. However, it also may be that elasmobranchs in general possess the necessary mechanisms to tolerate a variety of conditions due to their evolutionary history reaching back hundreds of millions of years when the climate was much more unfavourable than today. I have also examined temperature effects on blue spotted whiptail rays and looked at changes in blood chemistry upon exposure to elevated CO2 and low pH in sandbar sharks. Ultimately, my research program is set up to understand the evolutionary significance and functional importance of maintaining physiological performance during stress, address the impact of poor water quality, habitat degradation, and climate change, and predict capacity for acclimation and adaptation, as proposed for this research in reef sharks.


In your opinion, how can people help save sharks?

Education, communication, and outreach are key. We need more basic science (e.g., how do systems work, how resilient are different species and what is the basis… habitat, evolutionary history, development/life-history?) so that we can apply this knowledge to ask and answer questions about contemporary issues plaguing elasmobranch populations such as climate change, habitat destruction, overfishing, etc. This alone needs to be communicated to the general public… the importance of basic science. Then, I think it’s important for scientists to learn how to communicate the importance of their research and findings to a broad audience, young (next generation of conservationists and scientists in some cases) and old (tax-payers).

How did you get involved in shark research and what advice would you give those interested in studying them?

I got involved first by focusing my graduate education (Master’s and PhD) and post-doctoral experience on comparative physiology, specifically fishes. As I mentioned, we need more of the basic science. Without it, we can’t properly ask and answer the questions needed to solve today’s problems. So, starting with a really solid foundation in the biology, physiology, biochemistry, and evolutionary history of a group of animals, such as the fishes, is a great place to begin. Then, if you understand how an organism works from the inside out and how it functions in its environment, you can choose the most appropriate species to study for the questions that you have.


Please provide links to any of your research you would like to showcase.

Summary: Field Trip to Moorea, French Polynesia.

Dr. Jodie Rummer TEDx talk

ARC Centre of Excellence for Coral Reef Studies

website: www.jodierummer.com

twitter: @physiologyfish.

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