by M. Kelsey Lane, Ph.D. student in Ocean, Earth and Atmospheric Sciences
Our eight-person team woke early to the clear blue skies of Catalina Island off the coast of Los Angeles, California. The beautiful island is a popular vacation destination, but we had other priorities as we jumped into another busy day of fieldwork. Someone hustled down to the laboratory before 7:00 AM to turn on the UV lights that mimicked the sun, suspended over the rows and rows of jars holding microscopic plankton called foraminifera, or forams, that we were growing. Three of us headed to the dock to take a boat offshore and tow the depths for more plankton. Everyone worked in the lab taking care of the forams in their tiny seawater jars. The tasks would keep us busy into the evening as we worked to farm forams for our climate research.
Forams are storytellers of a forgotten time. Their shells record the conditions that they live in, making them “proxies” or analogs for measuring climate change. Foram shell chemistry changes with changing temperatures, salinities, ocean pH, and many other parameters, including some we’re still exploring. The forams we study live as plankton drifting in the open ocean and grow shells out of calcium carbonate. They have intricate, beautiful chambered shells, many with spines to help catch food. When forams die, their dense shells sink to the sea floor and are often preserved as fossils, providing scientists with a unique opportunity to investigate the past by studying the foram fossil record going back millions of years. So, we can look at a 50-million-year-old foram fossil and say something about the ocean conditions at the time and place it grew.
The best way to establish these relationships is to grow foraminifera in controlled conditions and see how it changes their shell geochemistry. It’s a lot of effort to grow these small organisms, each about the size of a grain of sand and kept in their own individual jar, but they’re well worth the effort. Our multi-institution team came to the University of Southern California Wrigley Marine Science Center to help develop and improve climate proxies from modern foraminifera. It took a big team to capture, process and keep the hundreds of forams alive. The group from Columbia University and Vassar College explored how ocean acidification and warming temperatures are recorded in foraminifera shells. Our team from Oregon State University looked at how forams might incorporate trace metals to tell us more about ocean productivity, and I explored how the microbes living inside forams might be altering their shell geochemistry.
It felt strange to be so invested in the life cycle of a tiny, single-celled organism. We spent hours feeding each foram tiny brine shrimp, food that was often larger than the foram itself, and we all cheered when the hungry foram fed. We carefully watched as they grew chambers and spines, writing it all down in detailed logs. Some forams would die in culture or get pale and unhappy. If things we went well, the foram would reach its full size after a couple of weeks, then start to die and go ‘gam’ or gametogenic, the final stage of its life cycle. Although it was sad to watch them die, it was also exciting, because that was one more successful foram that had grown in our laboratory. We delicately extricated the foram and put the shell in a tiny slide, a precious data point that might help us understand more about the ocean’s past.
The month-long field season went quickly. Around the long hours in the lab or out on the water, we built a great community. We ended each workday swimming off the dock, exploring the island, kayaking nearby bays, or watching The New Girl and working through a massive puzzle (we got through about one a week!) Farming forams can be a busy job, but we had fun, too. Now we will spend the next few months at our home institutions processing all that data…
Follow more of Kelsey’s science on Twitter at @mkelsea and on the Foraminarium website