Who I am
Thanks to the movie and music industry, California has acquired a reputation as the land of endless summer. I grew up in one of the many cities in the county of Los Angeles and have lived in California for most of my life. I mention this fact because it has been integral in shaping who I am today and is perhaps why most of my research is based in California. When I was a child, my love for the ocean was fostered by my parents. One of my fondest memories is of my dad taking my sister and me to the beach every Monday night after he got home from work. Throughout my life, my parents have been supportive of my budding (and now realised) marine biologist endeavours. Whether it was after-school classes at local aquariums, day camps or taking me to visit colleges around the state that offered degrees in marine biology, my parents have been there every step of the way.
During my childhood, I became interested in shark research after reading the work of Dr Eugenie Clark. I was fascinated not only by her research on shark behaviour, but also because she was a woman in science who showed that shark research wasn’t just for men. While working on my Master’s at Cal State Long Beach, I forged my own path as a shark biologist. At college I became interested in environmental contaminants and since then I have been investigating patterns of accumulation and the implications they have for an animal’s fitness. Elasmobranchs (sharks, skates and rays) represent a unique model system in contaminant research and are also understudied in this area compared to birds, reptiles or mammals.
Where I work
Up and down the coast of California, the Pacific Ocean is more than just a body of water; it’s a way of life. What most people don’t realise is the impact that humans have on the adjacent marine areas. Think about it. More than 22 million people live in southern California alone, which is a larger population and higher density of humans than in many countries around the world. Of course, many people are aware of the human impacts that they can see, such as litter or oil spills. However, the pollution that people can’t see lasts just as long – if not longer.
I am interested in studying this unseen and often forgotten pollution. Many tons of organic contaminants were released into the southern California marine environment before they were banned in the 1970s. In particular, DDT, the contaminant responsible for the thinning of bird eggshells made famous by Rachel Carson’s Silent Spring, was released in high proportions there. Because of this, animals from southern California have a unique ‘DDT signature’. While remediation efforts are ongoing, the high persistence of these contaminants in the environment is a concern. Since elasmobranchs are at the top of many food chains, they have a tendency to accumulate high levels of contaminants, which is where my interest in this field came into being.
What I do
The short version of my research is that I study legacy contaminant concentrations in elasmobranchs. However, that is not enough to describe all the interesting questions that come with the territory. Legacy contaminants are contaminants whose production ceased decades ago, but they still remain in the environment because they do not degrade easily. Therefore, even though they are no longer being produced, they are still problematic because they persist in the environment. Contaminant research is a very exciting area and with respect to elasmobranchs is a relatively young field, so there is much work to be done and a lot of questions to be answered.
One of these questions relates to patterns of accumulation among species of open-water sharks in southern California. So far, our research indicates that newborn sharks begin life with a ‘starting amount’ of legacy contaminants that is passed on to them by their mothers during gestation in a process called maternal offloading. We have also documented that as these young sharks grow, the concentrations of their starting amount of contaminants become diluted. We hypothesise that this is due to the sharks’ inability to acquire the same amounts of these contaminants from their food at this point in their life. However, we have also demonstrated that much older, adult sharks have high levels of contaminants, such that the concentration curve of an animal over body size is predicted to look U-shaped. I am interested in examining the inflection point of this ‘U’ and investigating the factors that influence when there is a switch from contaminants being diluted to being accumulated. To do this, I will be examining contaminant concentrations for three species of shark: shortfin mako Isurus oxyrinchus, common thresher Alopias vulpinus and blue Prionace glauca. With the funds provided by SOSF, I hope to offer more insights into the biology of these animals by approaching it from a contaminant point of view.
I would be lying to you if I said that legacy organic contaminants that were released decades ago were the only harmful compounds that the marine environment has to deal with. The reality is that everything that gets flushed down toilets and sinks or goes down storm drains has the potential to reach the ocean. However, there are many great researchers investigating these issues and I am grateful that my study has a place among theirs.
Some pessimists might say, ‘Well, the damage has been done already.’ I would respond that researching these legacy contaminants has several roles. Firstly, the signatures animals pick up when they utilise different areas with unique contaminant proportions offer another option in the scientists’ toolbox to study the ecology of animals. Secondly, there is a need to study the potential physiological impacts of these contaminants because they are still in the environment. Thirdly, and perhaps most importantly, discussing legacy contaminants raises awareness about the impacts humans have on their environment. By starting the contaminant conversation, we can educate people about the influence that humans have had on the local marine environment and encourage them to think about how they want to leave the ocean and its inhabitants for future generations.